Thermochemical Response 

of Vinyl-Ester Resin 

by Bruce K. Fink, Travis A. Bogetti, Molly A. Stone, 

and John W. Gillespie, Jr. 

ARL-TR-2653 January 2002 

Approved for public release; distribution is unlimited. 

20020213 063 
The findings in this report are not to be construed as an 

official Department of the Army position unless so 

designated by other authorized documents. 

Citation of manufacturer’s or trade names does not 

constitute an official endorsement or approval of the use 

thereof. 

Destroy this report when it is no longer needed. Do not 

return it to the originator. 
Army Research Laboratory 

Aberdeen Proving Ground, MD 210053089 

ARL-TR-2653 January 2002 

Thermochemical Response 

of Vinyl-Ester Resin 

Bruce K. Fink and Travis A. Bogetti 

Weapons and Materials Research Directorate, ARL 

Molly A. Stone and John W. Gillespie, Jr. 

University of Delaware 

Approved for public release; distribution is unlimited. 
Abstract 

This report presents the thermochemical characterization of Dow Derakane 

411-C50 commercial vinyl-ester resin at low temperatures (2OO-40 “C). 

Differential scanning calorimetry (DSC) and torsional braid analysis (TBA) are 

the experimental techniques used to characterize the material behavior. The cure 

kinetics are studied using DSC and are modeled using a modified autocatalytic 

equation with a maximum degree of cure term. Also, the effect of inhibitors in 

the resin system is accounted for by an inhibitor depletion model. A timetemperature-transformation diagram is constructed for the material by 

measuring the times to gelation and vitrification using TBA. The glass transition 

temperature (Ts) is also characterized using the TBA and related to the degree of 

cure. It was found that the Ts and the degree of cure do not exhibit a linear 

relationship for this resin system. The findings presented in this work provide 

information for accurate cure modeling and process simulation of vinyl-ester 

materials. 

ii 
Contents 

List of Figures V 

List of Tables vii 

1. 

2. 

3. 

4. 

5. 

6. 

Introduction 1 

Chemistry 2 

2.1 Free-Radical Polymerization ......................................................................... 2 

2.2 Effect of Added Inhibitor on the Reaction Behavior ................................ .4 

Theory 5 

3.1 Degree of Cure Calculation ........................................................................... 5 

3.2 Kinetic Modeling.. .................. ;. ..................................................................... .6 

3.3 Time-Temperature-Transformation (ITT) Diagram.. .............................. 

.7 

Experimental Procedure 8 

Results and Discussion 9 

5.1 DSC Results ..................................................................................................... 9 

5.1.1 Degree of Cure Calculation .............................................................. 9 

5.1.2 Kinetic Parameters ......................................................................... .ll 

5.1.3 Degree of Cure Correlation ............................................................ 15 

5.1.4 Unusual Vinyl-Ester Resin Behavior ............................................ 16 

5.1.4.1 Microgel Formations ........................................................ 16 

5.1.4.2 Diffusional Limitations .................................................. .17 

5.1.4.3 Low Maximum Degree of Cure ..................................... 18 

5.2 TBA Results.. ................................................................................................ .19 

5.2.1 Typical TBA Isotherm and Ramp ................................................. 19 

5.2.2 Glass Transition Temperature vs. Degree of Cure .................... .20 

5.2.3 TTT Diagram- Times to Gelation and Vitrification.. ................ .23 

Conclusions 24 

. . . 

lu 
7. References 

Distribution List 

Report Documentation Page 

iv 

27 

29 

45 
List of Figures 

Figure 1. Styrene and vinyl-ester structures. . . . . . . . . . . . . . . . . . . . . . . ..-...................................... 3 

Figure 2. The effect of 4-methoxyphenol inhibitor on the degree of cure. . . . . . . . . . . . . . . 4 

Figure 3. Typical TTT diagram for a well-behaved epoxy system (Gillham 

and Enns 1994). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

Figure 4. DSC thermogram from an isothermal experiment at 40 “C. . . . . . . . . . . . . . . . . . . . 10 

Figure 5. Experimental isothermal degree of cure profiles for vinyl-ester 

resin cured at 20”, 30”, and 40 “C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

Figure 6. Linear fit of the maximum degree of cure as a function of cure 

temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..-......................................................................... 11 

Figure 7. Experimental data showing the rate of cure vs. the degree of cure 

for a 40 “C isothermal cure (second-order autocatalytic model) . . . . . . . . . . . . . . . . . . . . . . 12 

Figure 8. Experimental data showing the rate of cure vs. the degree of cure 

for a 40 “C isothermal cure (m and n as independent parameters) . . . . . . . . . . . . . . . . . . . 12 

Figure 9. Arrhenius plot of the rate constants for the autocatalytic equation. . . ...13 

Figure 10. Arrhenius plot showing the change in time for inhibitor depletion 

with cure temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

Figure 11. Lag-time model combined with the kinetic model. After the 

inhibitor concentration reaches zero, the cure-kinetic model begins. . . . . . . . . . . . . . . 15 

Figure 12. Fit of kinetic model to isothermal DSC data at 20”, 309 and 40 “C......16 

Figure 13. AFM micrograph showing the microgel formation early in the 

curing process for a vinyl ester, 70 “C isothermal cure (Brill et al. 1996).........17 

Figure 14. Relative rates of reaction of the vinyl-ester and styrene reactions 

for a 70 “C isothermal cure (as determined by FTIR spectroscopy) 

(BriIl et al. 1996) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

. 

Figure 15. Typical response observed from a TBA experiment for the 

isothermal cure (40 “C) of a glass braid specimen impregnated with 

vinyl-ester resin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

Figure 16. Ts vs: time for vinyl-ester resin. Data points taken with the TBA 

and the solid lines are based on a T,(cl) model fit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

Figure 17. Glass transition temperature vs. degree of cure. It is assumed that 

the degree of cure continues to increase to 1.0, and the T continues to 

increase to Tgm. The solid lines represent the T&a) mode! fit. . . . . . . . . . . . . . . . . . . . . . . . . . . 22 

Figure 18. General shape of the TTT diagram. Only data in the intermediate 

region were collected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 

V 
Vi 
List of Tables 

Table 1. Vinyl-ester DSC results from 209 30”, and 40 “C isothermal cures.........1 1 

Table 2. Kinetic parameters in the second-order autocatalytic model.. ................ .13 

Table 3. Arrhenius parameters for the rate constants in the second-order 

autocatalytic model. ............................................................................................... .14 

Table 4. Arrhenius parameters for the lag-time model.. ......................................... .15 

Table 5. Parameters for the T,( cx) model for vinyl ester, given in Kelvin.. ........... .23 

Table 6. Average times to gelation and vitrification for vinyl-ester resin.. .......... .23 

Vii 
. . . 

Vlll 
1. Introduction 

Vinyl-ester resins are being used extensively as a matrix for liquid-molding 

composite structures. Vinyl esters exhibit many attractive attributes, including 

low viscosity (enabling room-temperature infusion into a preform), roomtemperature cure, comparable properties with other commonly used resins, and 

relatively low cost. Unfortunately, however, the thermochemical response of 

vinyl-ester resins at low temperatures is not well understood. 

Knowledge of the cure kinetic behavior of a thermosetting resin is required in 

establishing appropriate processing strategies that help to ensure satisfactory 

quality and m-service performance characteristics in the composite. Cure-kinetic 

behavior involves the many interrelationships that exist between the degree of 

cure, temperature, time, and various material properties during the cure process. 

Resin viscosity strongly depends on the degree of cure. During liquid-molding 

processes, the time to infiltrate must be less than the resin gel time (i.e., the tune 

at which the viscosity approaches infinity) to ensure complete wetting. The glass 

transition temperature (T,) of the as-manufactured composite part is governed 

by the final degree of cure. Process-induced residual stress will also depend on 

degree of conversion through Ts dependence, as well as the spa concentration, 

process temperatures, and postcure methods. The complex interrelationship 

between all of these processing variables demonstrates the need to have a 

thorough understanding of spatial gradients in cure-dependent modulus and 

shrinkage that evolve during cure. These parameters can affect initial mold 

design, resin selection (including inhibitors used to control the cure-kinetic 

behavior of a thermoset system. 

In this work, differential scanning calorimetry (DSC) and torsional braid analysis 

(TBA) were used to characterize the cure-kinetic behavior of a vinyl-ester resin. 

Samples cured at low temperatures (i.e., room temperature) do not normally 

reach conversions as high as those cured at elevated temperatures. The 

conversion plateaus as the diffusional limitations physically prevent the material 

from fully reacting. The reaction slows down because the mobility of the 

unreacted monomer decreases. In this regime, the T, of the material continues to 

increase and is very sensitive to slight changes in degree of cure. The slight 

increase in degree of cure after this point is very difficult to measure using DSC. 

For the vinyl-ester system, when most of the vinyl ester has already reacted, the 

styrene conversion continues to increase, yet this corresponds to only a very 

small amount of reacting material. Since the remaining reaction occurs over a 

relatively long time and the thermal-generation rate is small, DSC is not sensitive 

enough to detect the heat being liberated. Therefore, DSC is unable to accurately 

characterize the cure advance in the late stages of cure when diffusional 

limitations control the reaction. 
TBA was used to study the physical changes occurring in the vinyl-ester resin 

during cure. The TBA showed that mechanical and chemical changes continue to 

occur within the resin system long after the maximum degree of cure is achieved. 

Increases in the resin stiffness (relative rigidity) and the Ts were measured by 

TBA at times beyond the point at which maximum degree of cure was reached. 

Also, Fourier transform infrared (FTIR) spectroscopy studies showed the styrene 

reaction continuing after the vinyl-ester reaction had reached a plateau. During 

these later stages of cure, the TBA was found to be very sensitive to the 

mechanical changes in the system, allowing full thermochemical characterization 

of the system. 

In this investigation, both DSC and TBA are used to conduct a comprehensive 

characterization of the thermochemical behavior of a vinyl-ester resin system 

during cure. The DSC describes the reaction up to the cure state near the point of 

maximum conversion. The TBA shows the further increase in T, and the 

temperature dependence of the curing mechanisms. 

2. Chemistry 

2.1 Free-Radical Polymerization 

Vinyl-ester resins consist of styrene and a vinyl-ester prepolymer monomer. The 

chemical structures of these compounds are shown in Figure 1. The vinyl ester 

provides the important polymer properties such as modulus, Ts, toughness, and 

durability. The styrene monomer is a reactive diluent. The main purposes of the 

styrene are to control the viscosity, improve the wetting behavior of the resin, 

and lower the cost of the overall resin system. 

Vinyl esters are synthesized from the reaction of an unsaturated carboxylic acid, 

such as methyl methacrylate, with an epoxy resin. Vinyl esters differ from 

unsaturated polyesters in having only carbon-carbon double bonds at the ends of 

the chain and only pendant hydroxyl groups. The carbon-carbon double-bond 

end group is known as a vinyl group. Vinyl-ester monomer contains two vinyl 

end groups that allow a cross-linked structure to form during the reaction, while 

reaction of the styrene extends the structure in a linear fashion. 

These monomers react through a free-radical polymerization. The mechanism of 

such a reaction is explained by Stevens (1990). For completeness, however, a 

brief summary of the three main steps of free-radical polymerization is given as 

follows: (1) initiation involving two reactions -formation of the initiator radical 

(R) and addition of the initiator radical to a monomer, (2) propagation of a 

monomer radical to another monomer molecule, and (3) termination of all 

growing chains due to lack of mobility of unreacted monomers. 

2 
45 1- Styrene 

/ 

Vinyl ester 

0 L 

Figure 1. Styrene and vinyl-ester structures. .! 

,o i 

? 

0 

n 

Possible initiators for a free-radical polymerization include peroxides and 

hydroperoxides, azo compounds, redox initiators, and photoinitiators (Stevens 

1990). The initiator should be relatively stable at room temperature but, to 

ensure practical reaction rates, should decompose rapidly at polymer processing 

temperatures. In the current vinyl-ester resin system, an organic hydroperoxide 

is used as the initiator. Initial radicals are formed through thermal 

decomposition of the peroxide initiator. The polymerization reaction then 

propagates through the addition of the monomer to the growing polymer chain 

and continues propagation of the radical to the new monomer site. The 

decomposition rate of the initiator can be raised at low temperatures by adding 

an accelerator or promoter, such as (dimethylamino) benzene, cobalt 

naphthenate, or dimethyl aniline (DMA). 

The vinyl-ester resin used in this investigation is Dow Derakane 411-C50 

commercial resin, containing nominally 50 weight-percent styrene. The amount 

and type of initiator used in the system is 2 weight-percent Trigonox 239 A, 

produced by Akzo Co. This initiator contains 45% cumyl hydroperoxide, 45% 

carboxylic ester, and 10% cumyl acid. Cobalt napthenate (CoNap), containing 

6% cobalt, was used as an accelerator. CoNap accelerator was added in the 

amount of 0.2 weight-percent to induce the decomposition of the initiator at low 

curing temperatures. An inhibitor, 4-methoxyphenol, was added to the system 

in the amount of 0.3 weight-percent. The purpose of the inhibitor, as well as its 

effect on the cure reaction, is discussed next. Also present in the commercial 

vinyl-ester resin is an inhibitor to lengthen the shelf life. The type of inhibitor 

was not reported by DO&, nor was the nature of the carboxylic ester in the 

Trigonox 239 A reported by Akzo. 
2.2 Effect of Added Inhibitor on the Reaction Behavior 

During initial curing experiments at room temperature, DSC thermograms 

showed that reaction of the vinyl-ester resin began almost immediately after the 

CoNap accelerator and Trigonox initiator were added. This phenomena caused 

concern both from a processing and an experimental point of view. Because of 

the desire to better control and observe the start of the reaction, 4-methoxyphenol 

inhibitor was added to the system to delay the cure. 

Adding 0.3% 4-methoxyphenol delayed the start of the vinyl-ester reaction at 

cure temperatures between 20” and 40 “C. However, the reaction rate was found 

to increase after the inhibitor was added, as shown in Figure 2. The same results 

were found when a retardant, 2,4-pentadione, was added to the system. 

Separate studies were conducted by Ziaee and Palmese (1999), where an 

unknown inhibitor added by Dow was removed, leaving only vinyl ester and 

styrene. Comparisons between these rates of reaction showed that the reaction 

rate was decreased by removing the inhibitor. This result is consistent with the 

findings of the 2,4-pentadione and 4-methoxyphenol additions. It is concluded 

then that when adding an inhibitor or retardant to the vinyl-estek system, which 

is commonly done in processing, it should not be presumed that the rate of 

reaction will be unaffected. These results also imply that caution is necessary 

when changing the resin composition. 

0.6 t )’ 2’ -- 40°C 

I 

50 100 150 200 

Time (min) 

Figure 2. The effect of 4-methoxyphenol inhibitor on the degree of cure. 

4 
3. Theory 

3.1 Degree of Cure Calculation 

A common method of defining the extent of chemical conversion is by directly 

relating the heat of reaction to the degree of cure. For isothermal curing, it is 

assumed that the heat generated at different times during the reaction is directly 

proportional to the degree of cure. DSC is widely accepted as an accurate 

technique to measure the heat of reaction during cure and thus to determine the 

degree of conversion. 

The heat generated by a reaction at any time, t, is given by 

where dQ/dt is the rate of heat generation. Each resin system has an ultimate 

heat of reaction, LII&,, which would be given off if the reaction were to fully 

reach completion. For a particular resin system, AHUlt can be found by curing the 

system using a slow-temperature ramp and measuring the total heat of reaction. 

This value cannot normally be reached during a typical isothermal cure and is 

not often reached, even after a postramp experiment. At the completion of an 

isothermal cure, the total heat released is given by &I,,. A subsequent 

temperature ramp will yield a residual heat of reaction, AI&& Theoretically, the 

sum of LH+.~ and LIH~~~~ would equal &&,. Experimentally, however, this is not 

always the case. Also, the sum of A?IisO and AI-&, is not constant for various cure 

temperatures. Reasons for these phenomena may include a change in the curing 

mechanism that depends on the cure history or physical restrictions of the 

material that do not allow the full heat to be generated. In either case, it would 

not be accurate to use the sum of the isothermal and residual heats of reaction as 

the basis for 100% cure. In this work, full cure is based on the ultimate heat of 

reaction, A&, measured from the DSC experimental temperature ramps. 

Therefore, the method chosen for calculating the degree of cure at any time is 

based on the following equation: 

a(t)= 9. 

ult (2) 

This equation states that the degree of cure at any time, a(t), is determined by the 

percentage of the total available heat of reaction that has been released. Also, the 

rate of cure is proportional to the rate of heat being released, dQhdt, at an 

isothermal temperature, TI, and is given by 

5 
As mentioned previously, 100% conversion is not often reached during an 

isothermal cure, especially at low cure temperatures such as those studied in this 

investigation. Therefore, equation 2 can never reach unity, and a maximum 

degree of cure, a-, is realized that is less than unity. 

The maximum degree of cure is given by the following equation: 

The heat of reaction at the end of an isothermal experiment, A&,,, will increase as 

the cure temperature increases; therefore, the maximum degree of cure will also 

increase. Experiments have shown that the maximum degree of cure increases 

linearly with an increase in isothermal cure temperature (Michaud 1996). A 

function describing a-CT) can then be extrapolated to nearby temperatures. 

3.2 Kinetic Modeling 

When the exact reaction mechanism is not known, models based on empirical 

rate laws are frequently used to describe the rate of cure. Depending on the type 

of reaction, various kinetic models have been used to approximate the curing 

process of thermosetting resins. 

The autocatalytic model has been widely used to describe the kinetics of some 

epoxy resins and, more recently, has been found to fit the cure behavior of vinylester resins. The autocatalytic equation allows for an induction period before the 

reaction, which is typical of many thermosets. An autocatalytic reaction is 

defined as a reaction in which one of the products of the reaction acts as a 

catalyst (Levenspiel 1972). A product must be present if the reaction is to 

proceed at all. At the beginning of the reaction, a very small concentration of 

product usually exists, and the reaction rate is low. As more product is formed, 

the reaction rate rises to a maximum. Finally, the rate decreases as the reactant is 

consumed. The following autocatalytic model was suggested by Kamal and 

Sourour (1973) and is recommended by other workers to describe the rate of cure 

for certain thermosetting resins (Dillman and Seferis 1987; Han and Lem 1983; 

Hong and Chung 1991; Lee and Lee 1994; Michaud 1996; Yi et al. 1995), as in 

2= (k, +k,a”).(I--a)“. (5) 

In equation 5, kl and k2 are reaction rate terms, and m and n are exponential 

constants. Han and Lem (1983) have found k, and k2 experimentally for a vinylester resin system while assuming a second-order reaction, m + n = 2. The 

6 
reaction-rate terms in equation 5 are assumed to follow an Arrhenius 

temperature dependency such that 

Ink, =lnA,-(EJRT) and Ink, =lnA,-(EJRT), 

where AI and A2 are pre-exponential coefficients, E,, and En are activation 

energies, and R and T are the universal gas constant and temperature, 

respectively. It has often been found that the k, term in equation 5 can be 

neglected. However, for the vinyl-ester resin system used in this investigation, 

the kl term was found to be important in maintaining numerical stability of the 

solution technique due to cure rate changes occurring early in the reaction. This 

point is explained in further detail by Stone (1997). Based on the findings 

presented by Michaud (1996) for a similar vinyl-ester resin system, the 

exponential constants m and n were assumed to be constant and independent of 

temperature. 

The activation energy of a reaction can be determined by measuring the times to 

specific conversions for various cure temperatures. This method is often used 

with the autocatalytic model by assuming that the reaction-rate terms follow an 

Arrhenius temperature distribution, as shown in equation 6. A nonlinear 

regression technique is used to fit the experimental rate data to the kinetic model. 

A logarithmic plot of the rate term, k,, vs. the inverse cure temperature gives a 

straight line with a slope equal to the activation energy, Eal, and an intercept 

value equal to the pre-exponential parameter, AI. In this investigation, the 

autocatalytic model had to be modified to fit the vinyl-ester resin system. In 

equation 5, the numerical constant 1 is replaced with an a- term to capture the 

change in maximum conversion with the cure temperature. The following rate 

equation is therefore used in this work: 

2 = (k, +k2am).(amm -c$, 

where the temperature dependence on am is discussed in a subsequent section. 

3.3 Time-Temperature-Transformation (TTT) Diagram 

The TTT diagram is a useful method for displaying the various phase transitions 

that a thermoset material experiences during cure (Gillham and Enns 1994). The 

relationships between material transitions and material properties can be easily 

shown. The TTT diagram is constructed by plotting the time to reach a material 

transition for each isothermal temperature. A typical TIT diagram for a wellbehaved epoxy system is shown in Figure 3. 
t , SOL-GELGLASS 3 

log Time 

Figure 3. Typical TILT diagram for a well-behaved epoxy system (Gillham and Enns 

1994). 

During a cure reaction, there are four main physical states that the thermoset 

material may experience: (1) liquid, (2) ungelled (sol) glass, (3) gelled rubber, and 

(4) gelled glass. These material phases, as well as transition tunes, are 

conveniently identified in the TIT diagram. Three temperatures are important to 

notice in the TTT diagram: (1) the initial Ts, (Tso); (2) the final Ts, (TsT, and (3) the 

point where the gelation and vitrification times occur simultaneously (s+Ts). A 

curve can be drawn starting at Ts 0, connecting all the vitrification points and 

ending at Tgm. This curve typically exhibits an s-shape. Lines representing the 

times to gelation and other isoconversion lines can be added. By identifying 

where the isothermal cure temperature (T,,) occurs in relation to the three 

characteristic Ts’s, important information on the state of the final material can be 

concluded. 

4. Experimental Procedure 

A DuPont 700 DSC was used to analyze the kinetic behavior of the material. 

When characterizing the vinyl-ester resin, isothermal DSC runs at temperatures 

of 20”, 30”, and 40 “C were conducted. A liquid-nitrogen purge was maintained 

8 
during the experiment, and hermetically sealed pans were used. A weight of 

more than 1.0% was not accepted. The heat flow was then measured to allow for 

calculating the degree and rate of cure. An Arrhenius temperature dependency 

was assumed for the rate constant, thus providing the parameters necessary to 

model the cure kinetics. 

A TBA was used to characterize the time-temperature dependence of the T, and 

rigidity associated with the cure and to measure the times to specific material 

transitions. TBA is a dynamic mechanical technique capable of capturing the 

material behavior through the liquid, rubbery, and glassy stages of cure. The 

TBA sample consists of a glass braid substrate saturated with liquid resin. As the 

material cures, torsional oscillations are applied and the change in the damping 

response of the braid is measured. The anisotropy of the braid allows the 

torsional rigidity to be dominated by the resin. The temperature was carefully 

controlled during the experiment, and a liquid-nitrogen purge was used. The 

times to gelation and vitrification were measured during isothermal cures, as 

well as the increasing rigidity. The increase in Ts during cure was tracked by 

quenching the specimen at various stages in the cure and increasing the 

temperature through the T,. 

5. Results and Discussion 

5.1 DSC Results 

5.1.1 Degree of Cure Calculation 

In Figure 4, the area under the isothermal curve was calculated at each time 

increment, and the instantaneous degree of cure was calculated from 

equation 2. A value of 420 J/g for AHUlt was experimentally determined by 

ramping the system from room temperature to 250 “C at 5 OC/min. A similar 

AZ&, value of 425 J/g was determined by Palmese et al. (1998). Typical 

experimental degree of cure vs. time curves for various isothermal temperatures 

are shown in Figure 5. The resin conversion increases with increasing cure 

temperature, and the total cure time decreases. The effect of the added inhibitor 

can be seen by the time it takes for the reaction to begin. It is evident that 

inhibitor effectiveness is greater for lower cure temperatures. 

Table 1 shows the DSC results from the three isothermal conditions with 

equation 4 used to calculate CX-. Ideally, the sum of the isothermal and residual 

heats of reaction would give the achievable heat of reaction for the system. 

However, it can be seen from Table 1 that this is not the case. The low heat of 

reaction generated during the isothermal cure is due to increased 

9 
-0.10 I I I I I I I 

0 20 40 60 80 100 120 140 

Time (min) 

Figure 4. DSC thermogram from an isothermal experiment at 40 “C. 

0 50 100 150 200 250 300 

Time (min) 

Figure 5. Experimental isothermal degree of cure profiles for vinyl-ester resin cured at 

20", 30", and 40 “C. 

diffusional limitations at lower cure temperatures. This results in a maximum 

degree of cure of less than one. The maximum degree of cure is expressed as a 

linear function of temperature in equation 8, 

a,,(T)=O.53407+(0.0044572)T(oC). (8) 

10 
Table 1. Vinyl-ester DSC results from 20”, 30”, and 40 “C isothermal cures. 

Temp. 

(“C) 

AHiso AHred AHto ta, a max 

(J/g) (J/g) (J/g) 

20 261.2 f 7.7 100.1 f 1.8 361.3 + 6.2 0.6217+0.0187 

30 281.6 k12.7 85.0 k4.4 366.6 t17.3 0.6705 + 0.0307 

40 278.6 k3.8 58.5 k2.3 357.1 + 1.6 0.7110 + 0.0072 

At lower temperatures, therefore, a lower a,,,,, is expected, as shown in Figure 6. 

The residual heats of reaction were found to decrease as the isothermal 

temperature increased. This is in agreement with other reports showing the 

residual heat to be a linearly dependent function of temperature, decreasing with 

increasing temperature (Lee and Han 1987). This behavior appears to be 

reasonable since the degree of cure generally increases with increasing 

temperature. 

8 0.66 

&I 

$ 0.64 

f 0.62 

E .- 

x 0.60 

$ 15 

a 

20 25 30 35 40 45 

Cure Temperature (“C) 

Figure 6. Linear fit of the maximum degree of cure as a function of cure temperature. 

5.1.2 Kinetic Parameters 

A nonlinear regression technique was used to fit the cure rate curves to 

equation 7. A second-order reaction (m + n = 2) is typically assumed for 

thermosets. Figure 7 shows the experimental fit of the rate of change of the 

degree of cure to the second-order autocatalytic model for 20”, 30”, and 40 “C 

cures. The reaction rates appear to follow the autocatalytic shape, except at the 

two shoulders, where unusual rate changes were observed. Figure 7 also shows 

that the model overstates the maximum cure rate by as much as 7.2%. 

11 
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 

Degree of Cure (“Xi) 

Figure 7. Experimental data showing the rate of cure vs. the degree of cure for a 40 "C 

isothermal cure (second-order autocatalytic model). 

Reactions with orders other than second order were investigated in an attempt to 

improve model correlation with the data. A fit was conducted with both m and n 

as independent parameters. The result of this exercise is shown in 

Figure 8 for the. 40 “C isothermal cure. This model did not provide a significant 

improvement in the match to the experimental; consequently, the second-order 

model was used in this work. 

; 40°C Data 

w 0.020 

5 

= 0.015 

a7 

z 

K 0.010 

2 

5 0.005 m and n as independent independent parameters parameters 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 

Degree of Cure (%) 

Figure 8. Experimental data showing the rate of cure vs. the degree of cure for a 40 "C 

isothermal cure (m and n as independent parameters). 

12 
The four kinetic parameters in the second-order autocatalytic model, kl, k2, m, 

and n were determined from the data at each isothermal temperature. The 

resulting kinetic parameters are given in Table 2. Correlation coefficients 

indicate that using the autocatalytic model is acceptable for determining the 

kinetic parameters. However, as can be seen in Figure 7, the presence of the 

additional shoulders hinder a more exact fit. 

Table 2. Kinetic parameters in the second-order autocatalytic model. 

Temp. 

@/“A) (l,kk) 

m n Corr. 

(“C) Coeff. 

20 0.00031~0.00010 0.07771 f 0.00200 1.0759~ 0.015 0.725+ 0.015 0.7747 

30 0.00117 f 0.00001 0.12733 f 0.00700 1.038 f 0.004 0.762 f 0.004 0.7700 

40 0.00348+ 0.00007 0.16737iO.00200 1.037ztO.007 0.763~0.007 0.7875 

The average values of kl and kt for each isothermal cure were used to generate an 

Arrhenius plot, as shown in Figure 9. Linear equations for the rate constants are 

given in equations 9 and 10. The pre-exponential factors and activation energies 

were determined from the y-intercepts and slopes of the linear equations and are 

given in Table 3. 

In k, = 2.0808 - 20,719(1/RT,,). 

In k, = 27.173 - 96,346(1/ RT,,, ). 

-5 

-6 ,- a-, ---- ---fl----,, 

--- --8 

3 -78 (- - In k, 

e 

c -9 - 

Y 

S 

-11 - 

-12 '- 

3.85 

l/RT (x 104) 

(9) 

(10) 

Figure 9. Arrhenius plot of the rate constants for the autocatalytic equation. 

13 
Table 3. Arrhenius parameters for the rate constants in the second-order autocatalytic 

model. 

I Ea Wmol) I A W-1 I 

h 20,719 4.80 x 102 

b 96,346 3.80 x 10'3 

The kinetic model just presented represents the cure behavior of the resin. In 

addition to the kinetic model, the delay in cure caused by the reaction inhibitors 

represents another important aspect for consideration to accurately model the 

vinyl-ester cure. Inhibitors are present in the resin upon shipping, and an 

additional inhibitor was added to the resin in this investigation. These inhibitors 

need to be depleted by the system before any reaction can begin. This time lapse 

is not accounted for in the cure-kinetic model just developed. Figure 5 showed 

that the length of time it takes for the reaction to begin does not change linearly 

with cure temperature. In fact, it was found to increase exponentially with 

decreasing cure temperature and can therefore be expressed using an Arrhenius 

temperature dependency. The complete description of cure is made by modeling 

the inhibitor depletion first, and then the general kinetic model. 

Arrhenius parameters to describe the rate of depletion of the inhibitor can be 

determined by plotting the inverse of the time for the reaction to start (&-) 

against the inverse cure temperature (l/Cm,). This Arrhenius plot is shown in 

Figure 10, and equation 11 provides the corresponding linear equation. The 

parameters 

h 

3.80 3.85 3.90 3.95 4.00 4.05 4.10 4.15 

l/RT (xl 0 4) 

Figure 10. Arrhenius plot showing the change in time for inhibitor depletion with cure 

temperature. 

14 
Z&t,,)= 26.093-83,052(l/RTL,,). 

Table 4. Arrhenius parameters for the lag-time model. 

Ea (J/m00 A (l/min) 

k 83,052 1.2884 x 1013 

When the two models (lag-time and cure-kinetic model) are combined, they can 

accurately predict the total reaction behavior of the resin, starting with the 

depletion of the inhibitor and continuing with the kinetic reaction. Figure 11 

shows how the two models combine. First, the lag-time model demonstrates the 

rate of depletion of the inhibitor, after which the kinetic model takes over with a 

description of the cure reaction. 

h 

E 1.0 

s 

mr; 0.8 

E 

E 

8 

0.8 

g 0.4 

0 

'0 0.2 

.f: 

a 

'E 0.0 

c 

e model Ki 

0.8 P 

m 

0.8 is (D 

0 

0.4 5 

0.2 2 

3 

0.0 22 

s 0 20 40 80 80 100 120 140 

Time (min) 

Figure 11. Lag-time model combined with the kinetic model. After the inhibitor 

concentration reaches zero, the cure-kinetic model begins. 

5.1.3 Degree of Cure Correlation 

The comparison of the cure simulation models and the experimental degree of 

cure data is shown in Figure 12. As shown, the inhibitor depletion model 

worked well to predict the amount of time that would elapse before the reaction 

progressed. As predicted, this behavior is not linear with temperature, but 

follows an Arrhenius temperature dependency. The fit is very good, showing 

that the combination of the kinetic model and inhibitor depletion model is 

capable of predicting the degree of cure at any time for cure temperatures 

15 
0.8 

e T 

0.7 

0.6 

a 

s 0.5 

0 

z 0.4 

a 

t! 

0.3 

g 0.2 

P 0.1 

0 

- Model 

0 50 100 150 200 250 300 350 400 

Time (min) 

Figure 12. Fit of kinetic model to isothermal DSC data at 20”, 30”, and 40 “C. 

between the experimental temperatures of 20”, 30”, and 40 “C. Also, it can be 

assumed that predictions will be accurate for temperatures within the 

temperature range that was characterized. 

5.1.4 Unusual Vinyl-Ester Resin Behavior 

Through the DSC testing, unusual curing behaviors were identified in the vinylester resin system. These behaviors can be explained in part by the interactions 

of separate chemical reactions and by the effects of a low curing temperature. 

During the reaction of the vinyl-ester resin system, competing reactions are 

taking place, specifically vinyl-ester addition to styrene and styrene addition to 

vinyl ester. The following interesting behaviors have been noticed. 

5.1.4.1 Microgel Formations 

As the vinyl-ester resin reacts, small clusters of vinyl ester, called microgels, may 

form. A gel is formed when the polymer swells in the presence of solvents. 

Microgels are small gel particles between 300 and 1000 pm and are tightly 

packed spheres that can be suspended in solvents (Stevens 1990). Vinyl-ester 

microgels form when the styrene solvent swells the polymer. The groups of 

microgels have some styrene monomers inside of them, but the majority of the 

remaining styrene monomers are in the surrounding areas. These microgels 

affect the diffusion of the monomers. Brill et al. (1996) have captured the 

microgel formation in a similar vinyl-ester resin cured at 70 “C using atomic force 

microscopy (AFM). This micrograph is shown in Figure 13. 

16 
nm 

Figure 13. AFM micrograph showing the microgel formation early in the curing process 

for a vinyl ester, 70 “C isothermal cure (Brill et al. 1996). 

5.1.4.2 Diffusional Limitations 

In Figure 4, a large exotherm and two plateaus were observed during the 

isothermal cure. The two plateaus show a sudden decrease in the reaction rate. 

This is unusual in a thermosetting cure, where typically the reaction rate 

increases to a maximum and then steadily decreases. Through the use of FTIR 

spectrometry, Ziaee and Palmese (1999) have shown that at low temperatures, 

the reaction rate of the vinyl ester is higher than the reaction rate of the styrene 

monomers in the initial stages of cure. Thus, in the beginning of the cure, the 

vinyl ester dominates the reaction; this means that for every styrene monomer 

attaching to the main chain, there is more than one vinyl-ester monomer 

attaching. The first shoulder is believed to be due to diffusion phenomena. At 

some point after the initial microgel structure has formed, the vinyl-ester 

microgels collapse, or tighten around themselves. This reduces the mobility of 

the vinyl-ester monomers, making it more difficult for them to reach free chain 

radicals. In addition, the styrene monomers are more restricted from reaching 

the free radicals in the microgel because of the difficulty they have in diffusing 

through the now tight microgel structure. This is believed to be the cause of the 

17 
sudden, temporary decrease in reaction rate. Once this microgel collapse has 

occurred, the reaction rate again begins to increase to its maximum rate. FTIR 

has also shown that when the vinyl-ester reaction rate reaches its maximum, the 

styrene reaction rate is still increasing (Brill et al. 1996; Ziaee and Palmese 1999). 

The FTIR results from Brill et al. are shown in Figure 14 for a similar vinyl-ester 

resin cured at 70 “C. The styrene continues to react long after the leveling off of 

the DSC thermogram occurs. The styrene monomers are very small and have 

fewer steric hindrances, which allows them to continue to reach reactive sites 

long after the vinyl-ester reaction has terminated. As the cure temperature is 

decreased, the differences in reaction rates become less distinct, and the curve 

more closely resembles a typical autocatalytic shape. 

1.00 

0.75 

0.50 

0.25 

0 10 20 

Time (min) 

30 

Figure 14. Relative rates of reaction of the vinyl-ester and styrene reactions for a 70 “C 

isothermal cure (as determined by FTIR spectroscopy) (Brill et al. 1996). 

5.1.4.3 Low Maximum Degree of Cure 

For any system, a maximum degree of cure, a,,,,,, is reached when diffusional 

limitations hinder the ability of the material to react. The low maximum degree 

of cure for the vinyl-ester system is due to the diffusional limitation being 

18 
reached at a lower conversion compared to that of high-temperature cures. This 

happens because the molecules have a low thermal energy to begin with. The 

maximum degree of cure is defined as the maximum conversion that can be 

detected by the DSC. This occurs soon after the material vitrifies or solidifies. 

Over an extended period of time, however, the degree of cure may slowly 

increase beyond a,,,,,. This is because the small styrene monomers are still able to 

diffuse through the solid material to find reactive sites. 

5.2 TBA Results 

5.2.1 Typical TBA Isotherm and Ramp 

Figure 15 shows the typical response observed from a TBA experiment for the 

isothermal cure (40 “C) of a glass braid specimen impregnated with vinyl-ester 

resin. Two log relationships are shown-Log(LogD) and Log(rigidity) vs. 

Log(time). The LogD relationship shows a maximum at material transitions and 

is calculated by measuring the decay of the successive peak amplitudes as the 

specimen responds to an applied torsional oscillation. The first peak in the LogD 

curve is identified as the molecular gelation or a liquid to rubber transition. The 

second, more prominent peak is identified as the vitrification. The vitrification 

peak corresponds with the maximum rate of change of the rigidity. The 

vitrification peak was found to occur earlier than the leveling-off point in the 

DSC thermogram, which is often taken as the vitrification. This occurrence is 

discussed further. The rigidity can be seen to continue to increase long after the 

vitrification peak has occurred and also long after the degree of cure has reached 

its maximum from DSC measurements. 

c I I 

-0.5 I - -f I 

-1.0 t 

t 

-1.5 

-2.0 

-2.51 

0 0 P 

Gelation o 

0 0 0 ooooo \ 

^ 

0 ” 

0 

0 

0.20 

0.10 

0.00 

6 

co 

-0.10 F 

0 

-0.20 c0 

-2 

-0.30 

1.5 2 

-0.40 

2.5 

Log (time [min] ) 

Figure 15. Typical response observed from a TBA experiment for the isothermal cure 

(40 “C) of a glass braid specimen impregnated with vinyl-ester resin. 

19 
5.2.2 Glass Transition Temperature vs. Degree of Cure 

The increase in Ts was measured from the initial uncured state of the resin to the 

final glassy state. The initial Tp, Tg 0 , was measured at -25 “C, and the maximum 

Tg, Tgm, was measured at 125 “C. Other studies of various vinyl-ester systems 

have reported similar Tg values (Hong and Chung 1991; Lee and Lee 1994). Also, 

Tp” for pure vinyl ester was measured at 137 “C, and Tp” for pure styrene was 

measured at 100 “C; therefore, 125 “C is a logical value for the mixture. 

Figure 16 shows the relationship of Tp with time for cure temperatures of 20”, 

30”, and 40 “C. The solid lines were generated from a T,(aj model fit (discussed 

later). The Tg increases rapidly at first, and then slightly above vitrification, the 

increase in T, becomes much slower. By definition, vitrification corresponds to 

the point where the Ts reaches the cure temperature (T, = T,,,,). After the glass 

has formed, the rate of T, increase slows considerably. However, at this point, 

the reaction has not necessarily been terminated. To illustrate the increase in Tp 

over an extended time, a 40 “C isothermal cure was carried out for 5580 min (73 

hr). Figure 16 shows that the Tp at 242 min was measured at 65 “C. After 5580 

min, the Ts was measured at 78 “C. Thus, approximately a 15% increase in Tp 

was realized over this extended cure period. This increase could be very 

important during long-term, room-temperature part storage or during aging. 

90 360 

70 340 

g :; 

320 

300 uii 

km 10 

- - - Model - 20°C 

A Data - 20°C 

-- - -- Model - 30°C 

A Data - 30°C 

- Model - 40°C 260 

240 

0 100 200 300 400 

Time (min) 

Figure 16. T, vs. time for vinyl-ester resin. Data points taken with the TBA and the solid 

lines are based on a T,(a) model fit. 

It was mentioned previously that the vitrification point as measured in the TBA 

occurs earlier than the leveling off of the degree of cure, as measured in the DSC. 

This leveling off is often assumed to indicate the vitrification. This may be an 

20 
accurate estimation for many epoxy resins, but is not accurate for the vinyl-ester 

resin system. In Figure 16, the T, approaches a plateau immediately after 

vitrification (Ts = Tm,), but begins to increase again before approaching a final 

plateau. The first plateau is reached when the vinyl-ester reaction terminates, 

thus slowing down the Ts increase. However, the styrene reaction continues and 

further increases the T,. The first plateau coincides directly with the vitrification 

point measured in the TBA (Ts = T,,), and the second plateau coincides directly 

with the leveling off, as seen in the degree of cure from the DSC. 

It has been suggested that the T, could be used to monitor the reaction progress 

much like the degree of cure (Gillham and Enns 1994). The Ts has the advantage 

of being much more sensitive in the later stages of the cure. However, a direct 

relationship between the degree of cure and T, must exist to use this technique. 

Because of the competing reactions involving the styrene and vinyl ester, the 

relationship between T, and degree of cure is only direct for a specific cure 

temperature. Thus, the relationship between Ts and degree of cure for a typical 

nonisothermal cure would depend on the temperature history. This greatly 

limits the use of T, as a conversion measurement by restricting its application to 

isothermal conditions. This temperature dependency also means that greater 

care must be used during production to achieve consistent and predictable part 

quality. 

The vinyl-ester cure process was stopped by quenching the specimen at various 

stages of cure using liquid nitrogen. The Ts at this cure stage was measured in 

the TBA by increasing the temperature up through the T, at 2 ‘C/nun. The T, 

was then plotted against the degree of cure for each isothermal temperature (see 

Figure 17). For other thermosets, such as epoxy and polyimide systems, the data 

points for various isothermal temperatures have been found to collapse on one 

master curve (Gillham and Enns 1994; Zukas 1994). However, as shown in 

Figure 17, this was not the case with the current system due to the competing 

reaction mechanism explained previously. 

The degree of cure axis, shown in Figure 17, can be divided into three regions. 

The first region shows a rapid increase in the T, for a very small increase in 

conversion. Region 1 represents the period before and near gelation, where 

significant physical changes are occurring in the resin, but chemical conversion is 

not yet significant. Region 2 shows a small increase in the T, over a large 

increase in the conversion. This region corresponds to the maximum rate of 

change in degree of cure, as shown in Figure 7. Region 2 occurs when the 

material passes through vitrification and approaches the maximum degree of 

cure that can be measured using DSC. There is evidence that the T, and, 

consequently, degree of cure, continue to increase during extended isothermal 

cures. If it is assumed that the T, will increase to T,” over an extended cure time 

and that the styrene conversion will slowly increase to unity, the endpoints 

shown in Figure 17 can be fixed. Region 3 represents the time frame when T, 

21 
400 

380 

360 

340 

320 

300 

280 

260 

I --- Model - 30°C A Data - 30°C 

1, I IO I 

let- 20°C 

-10 

-0.2 0 0.2 0.4 0.6 0.8 1 1.2 

Degree of Cure (%) 

Figure 17. Glass transition temperature vs. degree of cure. It is assumed that the degree 

of cure continues to increase to 1.0, and the T, continues to increase to T,“. 

The solid lines represent the T&a) model fit. 

and degree of cure approach their ultimate values at similar rates. Based on the 

complicated reaction mechanism of the vinyl ester, there is a possibility that 

various morphologies are being formed in these three separate regions. Further 

study into this area is necessary. 

Even though it was found that the Tp and degree of cure did not exhibit a direct 

relationship for this particular system, it was still desirable to develop an 

emperical model from the data. A mathematical expression describing the Tp 

explicitly in terms of the degree of cure is particularly convenient for 

implementation in cure-dependant residual stress modeling. Equation 12 was 

chosen because it has been successfully used by other investigators (Hong and 

ChLmg 1991; Gillham and Enns 1994; Zukas 1994). 

(12) 

In equation 12, the term (AC; /AC;) is used as a fitting parameter in this study. 

The data was fit to equation 12 in two separate regions, before vitrification 

(O<a<a;it) and after vitrification (ait <~2). The solid lines in Figure 17 represent 

the fit of this equation to the experimental data. The parameters that were used 

for the fit are given in Table 5. There are two fitting parameters in each region of 

22 
Table 5. Parameters for the Te( a) model for vinyl ester, given in Kelvin. 

the model, and the parameters (Ts’) and (T,“) are defined as the experimentally 

measured initial and final glass transition temperatures, respectively. The fit of 

the Ts vs. time curve (Figure 16) was generated from this model and follows the 

experimental data well. 

52.3 TTT Diagram- Times to Gelation and Vitrification 

The gelation and vitrification times were measured in the TBA for cure 

temperatures between 20” and 60 “C. The average time to the gelation and 

vitrification transitions are given in Table 6. 

Table 6. Average times to gelation and vitrification for vinyl-ester resin. 

Cure Temperature Average Gelation Average Vitrification 

PC) (mid (min) 

20 47.67 + 7.12 137.75 + 17.27 

30 26.00 + 4.24 56.50 + 5.51 

40 13.00 + 0.00 20.00 + 1.41 

50 - 15.00 + 0.00 

60 - 11.50 + 2.12 

Figure 18 shows a portion of the TIT diagram for the vinyl-ester system. It was 

not possible to experimentally show the upper section of the diagram. When the 

isothermal cure temperature was increased above 60 “C, a different curing 

mechanism was observed than that at lower temperatures. This hightemperature curing reaction was not studied in this investigation, nor was the 

reaction below 20 “C. The experimental values for Ts” and Ts” are shown as the 

limits of the ITT diagram at -25” and 125 “C, respectively. 

The gelation for isothermal curing temperatures above 40 “C could not be 

measured because of the fast nature of the reaction; however, if the gelation data 

points are extended, the selTs can be estimated at approximately -5 “C. When 

23 
I . 

Figure 

150 

1 Char region1 

- -e..... 

1.0 1.5 2.0 2.5 3.0 

Log Time 

18. General shape of the TTT diagram. Only data in the intermediate region 

collected. 

were 

plotted on a log-time TIT diagram (Figure IS), the gelation time exhibits a linear 

decrease with increasing cure temperature, given by the following equation: 

Zog(t,,)= 2.249-O.O282T,, . 

In the same region, the vitrification points also show a linear behavior, given by 

Zog(t,)= 2.585-O.O274T,, . (14 

The TTT diagram is useful in defining a material’s processing window. More 

specifically, equation 13 can be used to estimate times (for a given cure 

temperature) that would be required to infuse a part before gelation took place. 

6. Conclusions 

A number of conclusions were made from the investigation of the vinyl-ester 

resin system. First, it was shown that the overall cure reaction is consistent with 

an autocatalytic behavior. The cure rate increased to a maximum value and then 

decreased. A traditional autocatalytic model fit the data when a modification 

was made to account for a maximum extent of cure, am,, which is less than one. 

The inhibitor in the resin system was found to be more effective at lower curing 

temperatures. The time to deplete the inhibitor in the system as a function of 

24 
cure temperature was modeled using an Arrhenius temperature distribution. 

The combination of the kinetic autocatalytic model and the inhibitor depletion 

model resulted in an accurate description of the cure reaction. 

The curing reaction was found to continue long after the DSC was capable of 

accurately measuring the heat of reaction. TBA proved to be very sensitive and 

was able to detect physical changes oc cm-ring in these later curing stages. The Ts 

did not reach its maximum value at any of the temperatures studied for the time 

durations measured. However, there is evidence that the Ts is still increasing 

over extended cure times and could reach its ultimate value. 

The vinyl-ester curing mechanism was found to have competing reactions 

occurring between the vinyl ester and styrene. The formation of microgels at 

early stages in the cure may have affected the progress of the cure. This could 

contribute to the unusual changes in the reaction rate that were seen in the DSC 

thermograms. The vinyl-ester curing mechanism was also found to be 

temperature dependent, thus complicating the extension of isothermal cure 

models to nonisothermal cases. The Ts was found to increase in a path, 

depending on the isothermal cure temperature. This limited the use of Ts as an 

alternative measure of conversion. 

The Ts for each isothermal temperature was modeled as a function of the degree 

of cure using a commonly used expression. Because of the shape of the T&a) 

curve for the vinyl-ester resin, this equation was applied in two regions, before 

vitrification and after vitrification. In addition to understanding the relationship 

between the Ts and degree of cure, this model is particularly convenient for 

implementation in cure-dependant residual-stress modeling. 

Room-temperature curing resins have not been studied as extensively as higher 

temperature systems. The cure reaction has proven to be significantly different 

than higher temperature reactions and very sensitive to temperature. Continued 

investigations into the curing mechanism and the resulting mechanical 

properties would help to fully understand the low-temperature reactions and the 

effects of processing conditions. Also, studies that investigate the morphologies 

that develop at various cure stages may give further insight into the formation of 

the vinyl-ester structure. 

25 
INTENTIONALLYLEFTBLANK. 

26 
7. References 

Brill, R. P., R. L. McCullough, and G. R. Palmese. “Effect of Resin Formulation 

and Reaction Temperature on the Curing Kinetics of Vinyl-Ester Resins.” 

Proceedings, American Society of Composites, II th Annual Technical Conference, 

p. 576, October 1996. 

Dillman, S. H., and J. C. Seferis. “Kinetic Viscoelasticity for the Dynamic 

Mechanical Properties of Polymer Systems.” JoumaZ of Macromolecular 

Science-Chemistry, September 1987. 

Gillham, J. K., and J. B. Enns. “On the Cure and Properties of Thermosetting 

Polymers Using Torsional Braid Analysis.” Trends in Polymer Science, vol. 2, 

no. 12, December 1994. 

Han, C. D., and K. W. Lem. “Curing Kinetics of Unsaturated Polyester and 

Vinyl-Ester Resins.” Chemorheology of Thermosetting Polymers, edited by 

C. A. May, American Chemical Society, Washington, DC, pp. 201-221,1983. 

Hong, M. S., and I. J. Chung. “The Cure Behavior of Vinyl-Ester Resin With Low 

Profile Additive I. Cure Kinetics and TTT Cure Diagram.” PoZymer Journal, 

vol. 23, no. 6, pp. 747-755,1991. 

Kamal, M. R., and S. Sourour. “Kinetics and Thermal Characterization of 

Thermoset Cure.” Polymer Engineering and Science, vol. 13, no. 1, pp. 57-64, 

1973. 

Lee, D., and C. D. Han. “A Chemorheological Model for the Cure of Unsaturated 

Polyester Resin.” Polymer Engineering and Science, vol. 27, no. 13, July 1987. 

Lee, J. H., and J. W. Lee. “Kinetic Parameters Estimation for Cure Reaction of 

Epoxy Based Vinyl-Ester Resin.” Polymer Engineering and Science, vol. 34, 

no. 7, pp. 742-749, May 1994. 

Levenspiel, 0. Chemical Reaction Engineering, Znd’ed. New York: John Wiley and 

sons, 1972. 

Michaud, D. J. “Investigation of Curing Behavior in Thick Thermoset 

Composites Manufactured by Resin Transfer Molding.” Master’s thesis, 

University of Delaware, Newark, DE, 1996. 

Palmese, G. R., 0. A. Andersen, and V. M. Karbhari. “Effect of Glass Fiber Sizing 

on the Cure Kinetics of Vinyl-Ester Resins.” Composites Part A: Applied 

Science and Manufacturing, vol. 30, no. 1, pp. ll-18,1998. 

Stevens, M. I?. Polymer Chemistry, An Introduction, 2nd ed. New York: Oxford 

University Press, pp. 70-103,199O. 

27 
Stone, M. A. “Thermo-Chemical and Thermo-Mechanical Response of Reacting 

Polymers.” Master’s thesis, University of Delaware, Newark, DE, 1997. 

Yi, S., H. H. Hilton, and M. F. Al-mad. “Curing Process Induced Viscoelastic 

Residual Stress in Polymer Matrix Laminated Composites.” Submitted to 

ASME Journal of Applied Mechanics, 1995. 

Ziaee, S., and G. R. Palmese. “Effects of Temperature on Cure Kinetics and 

Mechanical Properties of Vinyl-Ester Resins.” JoumaI of Polymer Science, 

Part B: Polymer Physics, vol. 37, no. 7, pp. 725-744,1999. 

Zukas, W. “Torsional Braid Analysis of the Aromatic Amine Cure of Epoxy 

Resins.” Journal of Applied Polymer Science, vol. 53, pp. 429-440,1994. 

28 
NO. OF 

COPIES ORGANIZATION 

2 DEFENSE TECHNICAL 

INFORMATION CENTER 

DTIC OCA 

8725 JOHN J KINGMAN RD 

sTEo944 

FT BELVOIR VA 22060-6218 

1 HQDA 

DAM0 FDT 

400 ARMY PENTAGON 

WASHINGTON DC 20310-0460 

1 OSD 

OUSD(A&T)/ODDR&E( 

DRRJTREW 

3800 DEFENSE PENTAGON 

WASHINGTON DC 20301-3800 

1 COMMANDING GENERAL 

US ARMY MATERIEL CMD 

AMCRDA TF 

5001 EISENHOWER AVE 

ALEXANDRIA VA 223330001 

1 INST FOR ADVNCD TCHNLGY 

THE UNIV OF TEXAS AT AUSTIN 

3925 W BRAKER LN STE 400 

AUSTIN TX 787596316 

1 US MILITARY ACADEMY 

MATH SC1 CTR EXCELLENCE 

MADN MATH 

THAYER HALL 

WEST POINT NY 109961786 

1 DIRECTOR 

US ARMY RESEARCH LAB 

AMSRL D 

DRDSMlTH 

2800 POWDER MILL RD 

ADELPHI MD 207831197 

1 DIRECTOR 

US ARMY RESEARCH LAB 

AMSRLCIAIR 

2800 POWDER MILL RD 

ADELPHI MD 207831197 

NO. OF 

COPIES ORGANIZATION 

3 DIRECTOR 

US ARMY RESEARCH LAB 

AMSRL CI LL 

2800 POWDER MILL RD 

ADELPHI MD 207831197 

3 DIRECTOR 

US ARMY RESEARCH LAB 

AMSRL CI IS T 

2800 POWDER MILL RD 

ADELPHI MD 20783-1197 

ABERDEEN PROVING GROUND 

2 DIR USARL 

AMSRL CI LP (BLDG 305) 

29 
NO. OF 

COPIES ORGANIZATION 

1 

2 

DIRECTOR 

US ARMY RESEARCH LAB 

AMSRL Cl’ CA 

D SNIDER 

2800 POWDER MILL RD 

ADELPHI MD 207831145 

DIRECTOR 

US ARMY RESEARCH LAB 

AMSRL CI IS R 

2800 POWDER MILL RD 

ADELPHI MD 20783-1145 

DIRECTOR 

US ARMY RESEARCH LAB 

AMSRL OF’ SD TL 

2800 POWDER MILL RD 

ADELPHI MD 207831145 

DPTY ASST SECY FOR R&T 

SARD l-T 

THE PENTAGON 

RM 3EA79 

WASHINGTON DC 20301-7lOO 

COMMANDER 

US ARMY MATERIEL CMD 

AMXMI INT 

5001 EISENHOWER AVE 

ALEXANDRIA VA 223330001 

COMMANDER 

US ARMY ARDEC 

AMSTA AR CC 

G PAYNE 

J GEHBAUER 

C BAULIEU 

H OPAT 

PICATINNY ARSENAL NJ 

07806-5000 

COMMANDER 

US ARMY ARDEC 

AMSTA AR AE WW 

E BAKER 

J PEARSON 

PICATINNY ARSENAL NJ 

07806-5000 

NO. OF 

COPIES ORGANIZATION 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR FSE 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR TD 

C SPINELLI 

MCATINNY ARSENAL NJ 

07806-5000 

6 COMMANDER 

US ARMY ARDEC 

AMSTA AR CCH A 

W ANDREWS 

S MUSALLI 

R CARR 

M LUCIANO 

E LOGSDEN 

T LOUZEIRO 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR CCH I’ 

J LUTZ 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR FSF T 

C LMCCHIA 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY ARDEC 

AMSTA ASF 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR QAC T C 

C PATEL 

PICATINNY ARSENAL NJ 

07806-5000 

30 
NO. OF 

COPIES ORGANIZATION 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR M 

D DEMELLA 

PICATINNY ARSENAL NJ 

07806-5000 

3 COMMANDER 

US ARMY ARDEC 

AMSTA AR FSA 

A WARNASH 

B MACHAK 

M CHIEFA 

MCATINNY ARSENAL NJ 

07806-5000 

2 COMMANDER 

US ARMY ARDEC 

AMSTA AR FSP G 

M SCHIKSNIS 

D CARLUCCI 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR FSP A 

I’ KISATSKY 

PICATINNY ARSENAL NJ 

078065000 

2 COMMANDER 

US ARMY ARDEC 

AMSTA AR CCH C 

H CHANIN 

S CHICO 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR QAC T 

D RIGOGLIOSO 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR WET 

T SACHAR 

BLDG 172 

PICATINNY ARSENAL NJ 

07806-5000 

NO. OF 

COPIES ORGANIZATION 

1 US ARMY ARDEC 

INTELLIGENCE SPECIALIST 

AMSTA AR WEL F 

M GUERRIERE 

PICATINNY ARSENAL NJ 

07806-5000 

9 COMMANDER 

US ARMY ARDEC 

AMSTA AR CCH B 

P DONADIA 

F DONLON 

P VALENTI 

CKNUTSON 

G EUSTICE 

S PATEL 

G WAGNECZ 

R SAYER 

F CHANG 

PICATINNY ARSENAL NJ 

07806-5000 

6 COMMANDER 

US ARMY ARDEC 

AMSTA AR CCL 

F PUZYCKI 

R MCHUGH 

D CONWAY 

E JAROSZEWSKI 

R SCHLENNER 

M CLUNE 

PICATINNY ARSENAL NJ 

07806-5000 

5 PM SADARM 

SFAE GCSS SD 

COL B ELLIS 

M DEVINE 

W DEMASSI 

J PRITCHARD 

S HROWNAK 

PICATINNY ARSENAL NJ 

07806-5000 

2 PEO FIELD ARTILLERY SYS 

SFAE FAS FM 

H GOLDMAN 

T MCWILLIAMS 

PICATINNY ARSENAL NJ 

07806-5000 

31 
NO. OF 

COPIES ORGANIZATION 

1 COMMANDER 

US ARMY ARDEC 

AMSTA AR WEA 

J BRESCIA 

PICATINNY ARSENAL NJ 

07806-5000 

12 PM TMAS 

SFAE GSSC TMA 

R MORRIS 

C KIMKER 

D GUZIEWICZ 

E KOPACZ 

R ROESER 

R DARCY 

R KOWALSKI 

R MCDANOLDS 

L D ULISSE 

C ROLLER 

J MCGREEN 

B PATTER 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY ARDEC 

PRODUCTION BASE 

MODERN ACI’Y 

AMSMC PBM K 

PICATINNY ARSENAL NJ 

07806-5000 

1 COMMANDER 

US ARMY TACOM 

PM ABRAMS 

SFAE ASM AB 

6501 ELEVEN MILE RD 

WARREN MI 48397-5000 

1 COMMANDER 

US ARMY TACOM 

AMSTA SF 

WARREN MI 48397-5000 

1 COMMANDER 

US ARMY TACOM 

PM BFVS 

SFAE GCSS W BV 

6501 ELEVEN MILE RD 

WARREN MI 48397-5000 

NO. OF 

COPIES ORGANIZATION 

1 DIRECTOR 

AIR FORCE RESEARCH LAB 

MLLMD 

D MIRACLE 

2230 TENTH ST 

WRIGHT PATTERSON AFB OH 

45433-7817 

1 OFC OF NAVAL RESEARCH 

J CHRISTODOULOU 

ONR CODE 332 

800 N QUINCY ST 

ARLINGTON VA 22217-5600 

1 US ARMY CERL 

R LAMP0 

2902 NEWMARK DR 

CHAMPAIGN IL 61822 

1 COMMANDER 

US ARMY TACOM 

PM SURVIVABLE SYSTEMS 

SFAE GCSS W GSI H 

M RYZYI 

6501 ELEVEN MILE RD 

WARREN MI 48397-5000 

1 COMMANDER 

US ARMY TACOM 

CHIEF ABRAMS TESTING 

SFAE GCSS W AB QT 

T KRASKIEWICZ 

6501 ELEVEN MILE RD 

WARREN MI 48397-5000 

1 COMMANDER 

WATERVLIET ARSENAL 

SMCWV QAE Q 

B VANINA 

BLDG 44 

WATERVLIET NY 12189-4050 

3 ARMOR SCHOOL 

ATZK TD 

R BAUEN 

J BERG 

A POMEY 

FT KNOX KY 40121 

32 
NO. OF 

COPIES ORGANIZATION 

2 HQ IOC TANK 

AMMUNITION TEAM 

AMSIO SMT 

R CRAWFORD 

W HARRIS 

ROCK ISLAND IL 61299-6000 

2 COMMANDER 

US ARMY AMCOM 

AVIATION APPLIED TECH DIR 

J SCHUCK 

FI’ EUSTIS VA 236045577 

14 COMMANDER 

US ARMY TACOM 

AMSTA TR R 

R MCCLELLAND 

D THOMAS 

J BENNETT 

D HANSEN 

AMSTA JSK 

S GOODMAN 

J FLORENCE 

K IYER 

D TEMPLETON 

A SCHUMACHER 

AMSTA TR D 

D OSTBERG 

L HINOJOSA 

B RAJU 

AMSTA CS SF 

H HUTCHINSON 

F SCHWARZ 

WARREN MI 48397-5000 

14 BENET LABORATORIES 

AMSTA AR CCB 

R FISCELLA 

M SOJA 

EKATHE 

M SCAVULO 

G SPENCER 

P WHEELER 

s KRuPsKI 

J VASILAKIS 

G FRIAR 

R HASENBEIN 

AMSTA CCB R 

S SOPOK 

E HYLAND 

D CRAYON 

R DILLON 

WATERVLIET NY 12X39-4050 

NO. OF 

COPIES ORGANIZATION 

DIRECTOR 

US ARMY AMCOM 

SFAE AV RAM TV 

D CALDWELL 

BLDG 5300 

REDSTONE ARSENAL AL 

35898 

NAVAL SURFACE WARFARE CTR 

DAHLGREN DIV CODE GO6 

DAHLGREN VA 22448 

US ARMY CORPS OF ENGINEERS 

CERD C 

T LIU 

CEW ET 

TTAN 

20 MASS AVE. NW 

WASHINGTON DC 20314 

US ARMY COLD REGIONS 

RSCH & ENGRNG LAB 

P DUlTA 

72 LYME RD 

HANOVER NH 03755 

USA SBCCOM PM SOLDIER SPT 

AMSSB PM RSS A 

J CONNORS 

KANSAS ST 

NATICK MA 01760-5057 

USA SBCCOM 

MATERIAL SCIENCE TEAM 

AMSSB RSS 

J HERBERT 

M SENNETT 

KANSAS ST 

NATICK MA 01760-5057 

OFC OF NAVAL RESEARCH 

D SIEGEL CODE 351 

J KELLY 

800 N QUINCY ST 

ARLINGTON VA 22217-5660 

NAVAL SURFACE WARFARE CTR 

TECH LIBRARY CODE 323 

17320 DAHLGREN RD 

DAHLGREN VA 22448 

33 
NO. OF 

COPIES ORGANIZATION 

1 NAVAL SURFACE WARFARE CTR 

CRANE DIVISION 

M JOHNSON CODE 20H4 

LOUISVILLE KY 402145245 

2 NAVAL SURFACE WARFARE CTR 

U SORATHIA 

C WILLIAMS CD 6551 

9500 MACARTHUR BLVD 

WEST BETHESDA MD 20817 

2 COMMANDER 

NAVAL SURFACE WARFARE CI’R 

CARDEROCK DMSION 

R PETERSON CODE 2020 

M CRl’TCHFIELD CODE 1730 

BETHESDA MD 20084 

8 DIRECTOR 

US ARMY NATIONAL GROUND 

INTELLIGENCE CTR 

D LEITER MS 404 

M HOLTUS MS 301 

M WOLFE MS 307 

S MINGLEDORF MS 504 

J GASTON MS 301 

W GSTA-ITENBAUER MS 304 

R WARNER MS 305 

J CRIDER MS 306 

220 SEVENTH ST NE 

CHARLOTTESVILLE VA 22091 

1 NAVAL SEA SYSTEMS CMD 

D LIE-SE 

2531 JEFFERSON DAVIS HWY 

ARLINGTON VA 22242-5160 

1 NAVAL SURFACE WARFARE Cl-R 

M LACY CODE B02 

17320 DAHLGREN RD 

DAHLGREN VA 22448 

1 EXPEDITIONARY WARFARE 

DIV N85 

F SHOUP 

2000 NAVY PENTAGON 

WASHINGTON DC 20350-2000 

NO. OF 

COPIES ORGANIZATION 

8 US ARMY SBCCOM 

SOLDIER SYSTEMS CENTER 

BALLISTICS TEAM 

J WARD 

w ZUKAS 

P CUNNIFF 

J SONG 

MARINE CORPS TEAM 

J MACKIEWICZ 

BUS AREA ADVOCACY TEAM 

w HASKELL 

AMSSB RCP SS 

W NYKVIST 

S BEAUDOIN 

KANSAS ST 

NATICK MA 01760-5019 

9 US ARMY RESEARCH OFC 

A CROWSON 

H EVERETT 

J PRATER 

G ANDERSON 

D STEPP 

D KISEROW 

J CHANG 

PO BOX 12211 

RESEARCH TRIANGLE PARK NC 

27709-2211 

8 NAVAL SURFACE WARFARE CTR 

J FRANCIS CODE G30 

D WILSON CODE G32 

R D COOPER CODE G32 

J FRAYSSE CODE G33 

E ROWE CODE G33 

T DURAN CODE G33 

L DE SIMONE CODE G33 

R HUBBARD CODE G33 

DAHLGREN VA 22448 

2 NAVAL SURFACE WARFARE CT R 

CARDEROCK DIVISION 

R CRANE CODE 2802 

C WILLIAMS CODE 6553 

3A LEGGETT CIR 

BETHESDA MD 20054-5000 

1 AFRL MLBC 

2941 P ST RM 136 

WRIGHT PATTERSON AFB OH 

45433-7750 

34 
NO. OF 

COPIES ORGANIZATION 

1 AFRL MLSS 

R THOMSON 

2179 12TH ST RM 122 

WRIGHT PATTERSON AFB OH 

454337718 

2 AFRL 

F ABRAMS 

J BROWN 

BLDG 653 

2977PSTSTE6 

WRIGHT PATTERSON AFB OH 

45433-7739 

1 WATERWAYS EXPERIMENT 

D SCOTT 

3909 HALLS FERRY RD SC C 

VICKSBURG MS 39180 

5 DIRECTOR 

LLNL 

R CHRISTENSEN 

S DETERESA 

F MAGNESS 

M FINGER MS 313 

M MURPHY L 282 

PO BOX 808 

LIVERMORE CA 94550 

1 AFRL MLS OL 

L COULTER 

7278 4TH ST 

BLDG 100 BAY D 

HILL AFB UT 840565205 

1 

EkT CCD TEST FORCE 

OSD JCCD 

R WILLIAMS 

3909 HALLS FERRY RD 

VICKSBURG MS 29180-6199 

3 DARPA 

M VANFOSSEN 

SWAX 

L CHRISTODOULOU 

3701 N FAIRFAX DR 

ARLINGTON VA 22203-1714 

1 DIRECTOR 

LOS ALAMOS NATIONAL LAB 

F L ADDESSIO T 3 MS 5000 

PO BOX 1633 

LOS ALAMOS NM 87545 

NO. OF 

COPIES ORGANIZATION 

SERDP PROGRAM OFC 

PM P2 

C PELLERIN 

B SMITH 

901 N STUART ST STE 303 

ARLINGTON VA 22203 

US DEPT OF ENERGY 

OFC OF ENVIRONMENTAL 

MANAGEMENT 

P RITZCOVAN 

19901 GERMANTOWN RD 

GERMANTOWN MD 208741928 

OAK RIDGE NATIONAL 

LABORATORY 

R M DAVIS 

PO BOX 2008 

OAK RIDGE TN 37831-6195 

OAK RIDGE NATIONAL 

LABORATORY 

C EBERLE MS 8048 

PO BOX 2008 

OAK RIDGE TN 37831 

DIRECTOR 

SANDIA NATIONAL LABS 

APPLIED MECHANICS DEPT. 

MS 9042 

J HANDROCK 

YRKAN 

J LAUFFER 

PO BOX 969 

LIVERMORE CA 94551-0969 

OAK RIDGE NATIONAL 

LABORATORY 

C D WARREN MS 8039 

PO BOX 2008 

OAK RIDGE TN 37831 

NIST 

M VANLANDINGHAM MS 8621 

J CHIN MS 8621 

J MARTIN MS 8621 

D DUTI-IINH MS 8611 

100 BUREAU DR 

GAITHERSBURG MD 20899 
NO. OF 

COPIES ORGANIZATION 

1 

3 

1 

1 

1 

I-JYDROGEOLOGIC INC 

SERDP ESTCP SPT OFC 

S WALSH 

1155 HERNDON PKWY STE 900 

HERNDON VA 20170 

NASA LANGLEY RSCH CTR 

AMSRL VS 

W ELBER MS 266 

F BARTLETT JR MS 266 

G FARLEY MS 266 

HAMPTON VA 23681-0001 

NASA LANGLEY RSCH Cl-R 

T GATES MS 188E 

HAMPTON VA 236613400 

FHWA 

E MUNLEY 

6300 GEORGETOWN PIKE 

MCLEAN VA 22101 

USDOT FEDERAL RAILRD 

M FATEH RDV 31 

WASHINGTON DC 20590 

CYTEC FIBERITE 

R DUNNE 

D KOHL1 

RMAYHEW 

1300 REVOLUTION ST 

HAVRE DE GRACE MD 21078 

MARINE CORPS 

INTLLGNC ACIVTY 

D KOSITZKE 

3300 RUSSELL RD STE 250 

QUANTICO VA 22134-5011 

DIRECTOR 

NATIONAL GRND INTLLGNC CTR 

IANG TMT 

220 SEVENTH ST NE 

CHARLOTTESVILLE VA 

22902-5396 

SIOUX MFG 

B KRIEL 

PO BOX 400 

FT TOT-TEN ND 58335 

NO. OF 

COPIES ORGANIZATION 

3TEX CORPORATION 

A BOGDANOVICH 

J SINGLETARY 

109 MACKENAN DR 

CARY NC 27511 

3M CORPORATION 

J SKILDUM 

3M CENTER BLDG 60 IN 01 

ST PAUL MN 551441000 

DIRECTOR 

DEFENSE INTLLGNC AGNCY 

TA5 

K CRELLING 

WASHINGTON DC 20310 

ADVANCED GLASS FIBER YARNS 

T COLLINS 

281 SPRING RUN LANE STE A 

DOWNINGTON PA 19335 

COMPOSITE MATERIALS INC 

D SHORTT 

19105 63 AVE NE 

PO BOX 25 

ARLINGTON WA 98223 

JPS GLASS 

L CARTER 

PO BOX 260 

SLATER RD 

SLATER SC 29683 

COMPOSITE MATERIALS INC 

R HOLLAND 

11 JEWEL CT 

ORINDA CA 94563 

COMPOSITE MATERIALS INC 

C RILEY 

14530 S ANSON AVE 

SANTA FE SPRINGS CA 90670 

SIMULA 

J COLTMAN 

R HUYETT 

10016 S 51ST ST 

PHOENIX AZ 85044 

36 
NO. OF 

COPIES 

2 

2 

1 

2 

1 

2 

1 

1 

1 

ORGANIZATION 

PROTECTION MATERIALS INC 

M MILLER 

F CRILLEY 

14000 N-w 58 CT 

MIAMI LAKES FL 33014 

FOSTER MILLER 

M ROYLANCE 

w ZUKAS 

195 BEAR HILL RD 

WALTHAM MA 023541196 

ROM DEVELOPMENT CORP 

ROMEARA 

136 SWINEBURNE ROW 

BRICK MARKET PLACE 

NEWPORT RI 02840 

TEXTRON SYSTEMS 

T FOLTZ 

M TREASURE 

1449 MIDDLESEX ST 

LOWELL MA 01851 

0 GARA HESS & EISENHARDT 

M GILLESPIE 

9113 LESAINT DR 

FAIRFIELD OH 45014 

MILLIKEN RSCH CORP 

HKUHN 

M MACLEOD 

PO BOX 1926 

SPARTANBURG SC 29303 

CONNEAUGHT INDUSTRIES INC 

J SANTOS 

PO BOX 1425 

COVENTRY RI 02816 

BATTELLE NATICK OPNS 

B HALPIN 

209 W CENTRAL ST STE 302 

NATICK MA 01760 

ARMTEC DEFENSE PRODUCTS 

S DYER 

85 901 AVE 53 

PO BOX 848 

COACHELLA CA 92236 

NO. OF 

COPIES ORGANIZATION 

NATIONAL COMPOSITE CENTER 

T CORDELL 

2000 COMPOSITE DR 

KETTERING OH 45420 

PACIFIC NORTHWEST LAB 

M SMITH 

G VAN ARSDALE 

R SHIPPELL 

PO BOX 999 

RICHLAND WA 99352 

AMOCO PERFORMANCE 

PRODUCTS 

M MICHNO JR 

J BANISAUKAS 

4500 MCGINNIS FERRY RD 

ALPHARETTA GA 30202-3944 

ALLIANT TECHSYSTEMS INC 

C CANDLAND MN11 2830 

C AAKHUS MN11 2830 

B SEE MN11 2439 

N VLAHAKUS MN11 2145 

R DOHRN MN11 2830 

S HAGLUND MN11 2439 

M HISSONG MN11 2830 

D KAMDAR MN11 2830 

600 SECOND ST NE 

HOPKINS MN 55343-8367 

SAIC 

M PALMER 

1410 SPRING HILL RD STE 400 

MSSH45 

MCLEAN VA 22102 

SAIC 

G CHRYSSOMALLIS 

3800 W 80TH ST STE 1090 

BLOOMINGTON MN 55431 

AAI CORPORATION 

T G STASTNY 

PO BOX 126 

HUNT VALLEY MD 21030-0126 

APPLIED COMPOSITES 

W GRISCH 

333 NORTH SIXTH ST 

ST CHARLES IL 60174 

37 
NO. OF 

COPIES ORGANIZATION 

1 CUSTOM ANALYTICAL 

ENG SYS INC 

A ALEXANDER 

13000 TENSOR LANE NE 

FLINTSTONE MD 21530 

1 OFC DEPUTY UNDER SEC DEFNS 

J THOMPSON 

1745 JEFFERSON DAVIS HWY 

CRYSTAL SQ 4 STE 501 

ARLINGTON VA 22202 

3 ALLIANT TECHSYSTEMS INC 

J CONDON 

E LYNAM 

J GERHARD 

WV01 16 STATE RT 956 

PO BOX 210 

ROCKET CENTER WV 267260210 

1 PROJECTILE TECHNOLOGY INC 

515 GILES ST 

HAVRE DE GRACE MD 21078 

3 HEXCEL INC 

R BOE 

PO BOX 18748 

SALT LAKE CITY UT 84118 

5 AEROJET GEN CORP 

D PILLASCH 

T COULTER 

C FLYNN 

D RUBAREZUL 

M GREINER 

1100 WEST HOLLYVALE ST 

AZUSA CA 91702-0296 

1 HERCULES INC 

HERCULES PLAZA 

WILMINGTON DE 19894 

1 BRIGS COMPANY 

J BACKOFEN 

2668 PETERBOROUGH ST 

HERNDON VA 22071-2443 

1 ZERNOW TECHNICAL SERVICES 

L ZERNOW 

425 W BONITA AVE STE 208 

SAN DIMAS CA 91773 

NO. OF 

COPIES ORGANIZATION 

GENERAL DYNAMICS OTS 

L WHITMORE 

10101 NINTH ST NORTH 

ST PETERSBURG FL 33702 

GENERAL DYNAMICS OTS 

FLINCHBAUGH DIV 

E STEINER 

B STEWART 

T LYNCH 

PO BOX 127 

RED LION PA 17356 

GKN AEROSPACE 

D OLDS 

15 STERLING DR 

WALLINGFORD CT 06492 

SIKORSKY AIRCRAFT 

G JACARUSO 

T CARSTENSAN 

BKAY 

S GARBO MS S330A 

J ADELMANN 

6900 MAIN ST 

PO BOX 9729 

STRATFORD CT 06497-9729 

PRATT & WHITNEY 

C WATSON 

400 MAIN ST MS 114 37 

EAST HARTFORD CT 06108 

AEROSPACE CORP 

G HAWKINS M4 945 

2350 E EL SEGUNDO BLVD 

EL SEGUNDO CA 90245 

CYI’EC FIBERITE 

M LIN 

W WEB 

1440 N KRAEMER BLVD 

ANAHEIM CA 92806 

UDLP 

G THOMAS 

PO BOX 58123 

SANTA CLARA CA 95052 

38 
NO. OF 

COPIES 

2 

3 

4 

2 

1 

1 

1 

ORGANIZATION 

UDLP 

R BARRETT MAIL DROP M53 

V HORVATICH MAIL DROP M53 

328 W BROKAW RD 

SANTA CLARA CA 95052-0359 

UDLP 

GROUND SYSTEMS DIVISION 

M PEDRAZZI MAIL DROP NO9 

A LEE MAIL DROP Nil 

M MACLEAN MAILDROP NO6 

1205 COLEMAN AVE 

SANTA CLARA CA 95052 

UDLP 

R BRYNSVOLD 

P JANKE MS 170 

4800 EAST RIVER RD 

MINNEAFOLIS MN 55421-1498 

BOEING ROTORCRAFT 

I? MINGURT 

P HANDEL 

800 B PUTNAM BLVD 

WALLINGFORD PA 19086 

BOEING 

DOUGLAS PRODUCTS DIV 

L J HART SMITH 

3855 LAKEWOOD BLVD 

DSOO 0019 

LONG BEACH CA 90846-0001 

LOCKHEED MARTIN 

SKUNK WORKS 

D FORTNEY 

1011 LOCKHEED WAY 

PALMDALE CA 93599-2502 

LOCKHEED MARTIN 

R FIELDS 

1195 IRWIN CT 

WINTER SPRINGS FL 32708 

MATERIALS SCIENCES CORP 

G FLANAGAN 

500 OFC CENTER DR STE 250 

F-T WASHINGTON PA 19034 

NO. OF 

COPIES ORGANIZATION 

NORTHRUP GRUMMAN CORP 

ELECTRONIC SENSORS 

& SYSTEMS DIV 

E SCHOCH MS V 16 

1745A W NURSERY RD 

LINTHICUM MD 21090 

GDLS DIVISION 

D BARTLE 

PO BOX 1901 

WARREN MI 48090 

GDLS 

D REES 

M PASIK 

PO BOX 2074 

WARREN MI 48090-2074 

GDLS 

MUSKEGON OPERATIONS 

W SOMMERS JR 

76 GETTY ST 

MUSKEGON MI 49442 

GENERAL DYNAMICS 

AMPHIBIOUS SYS 

SURVIVABTLITY LEAD 

G WALKER 

991 ANNAPOLIS WAY 

WOODBRIDGE VA 22191 

INST FOR ADVANCED 

TECH 

H FAIR 

I MCNAB 

P SULLIVAN 

S BLESS 

W REINECKE 

C F’ERSAD 

3925 W BRAKER LN STE 400 

AUSTIN TX 787595316 

CML ENGR RSCH FOUNDATION 

PRESIDENT 

H BERNSTEIN 

R BELLE 

1015 15TH ST NW STE 600 

WASHINGTON DC 20005 

39 
NO. OF 

COPIES ORGANIZATION 

1 ARROW TECH ASS0 

1233 SHELBURNE RD STE D8 

SOUTH BURLINGTON VT 

05403-7700 

1 R EICHELBERGER 

CONSULTANT 

409 W CATHERINE ST 

BEL AIR MD 210143613 

1 UCLA MANE DEFT ENGR IV 

HTHAHN ’ 

LOS ANGELES CA 900241597 

2 UNIV OF DAYTON 

RESEARCH INST 

RYKIM 

AKROY 

300 COLLEGE PARK AVE 

DAYTON OH 45469-0168 

1 UMASS LOWELL 

PLASTICS DEFT 

N SCHOTT 

1 UNIVERSITY AVE 

LOWELL MA 01854 

1 IIT RESEARCH CENTER 

D ROSE 

201 MILL ST 

ROME NY 13440-6916 

1 GA TECH RSCH INST 

GA INST OF TCHNLGY 

P FRIEDERICH 

ATLANTA GA 30392 

1 MICHIGAN ST UNIV 

MSM DEPT 

R AVERILL 

3515 EB 

EAST LANSING MI 48824-1226 

1 UNIV OF WYOMING 

D ADAMS 

PO BOX 3295 

LARAMIE WY 82071 

NO. OF 

COPIES ORGANIZATION 

2 

1 

1 

1 

1 

1 

1 

5 

PENN STATE UNIV 

R MCNITT 

C BAKIS 

212 EARTH ENGR 

SCIENCES BLDG 

UNIVERSITY PARK PA 16802 

PENN STATE UNIV 

R S ENGEL 

245 HAMMOND BLDG 

UNIVERSITY PARK PA 16801 

PURDUE UNIV 

SCHOOL OF AERO & ASTRO 

CTSUN 

W LAFAYETTE IN 47907-1282 

STANFORD UNIV 

DEFT OF AERONAUTICS 

& AEROBALLISTICS 

S TSAI 

DURANT BLDG 

STANFORD CA 94305 

UNIV OF MAINE 

ADV STR & C0M.I’ LAB 

R LOPEZ ANIDO 

5793 AEWC BLDG 

ORONO ME 04469-5793 

JOHNS HOPKINS UNIV 

APPLIED PHYSICS LAB 

P WIENHOLD 

11100 JOHNS HOPKINS RD 

LAUREL MD 20723-6099 

UNIV OF DAYTON 

JMWHITNEY 

COLLEGE PARK AVE 

DAYTON OH 45469-0240 

UNIV OF DELAWARE 

Cl-R FOR COMFOSITE MTRLS 

J GILLESPIE 

M SANTARE 

S YARLAGADDA 

S ADVANI 

D HEIDER 

201 SPENCER LABORATORY 

NEWARK DE 19716 

40 
NO. OF 

COPIES ORGANIZATION 

1 DEFT OF MATERIALS 

SCIENCE & ENGINEERING 

UNIVERSITY OF ILLINOIS 

AT URBANA CHAMPAIGN 

J ECONOMY 

1304 WEST GREEN ST 115B 

URBANA IL 61801 

1 NORTH CAROLINA STATE UNIV 

CIVIL ENGINEERING DEF’T 

W RASDORF 

PO BOX 7908 

RALEIGH NC 276967908 

1 UNIV OF MARYLAND 

DEFT OF AEROSPACE ENGNRNG 

A J VIZZINI 

COLLEGE PARK MD 20742 

1 DREXEL UNIV 

ASDWANG 

32ND & CHESTNUT ST 

PHILADELPHIA PA 19104 

3 UNIV OF TEXAS AT AUSTIN 

CTR FOR ELECTROMECHANICS 

J PRICE 

A WALLS 

J KlTZMILLER 

10100 BURNET RD 

AUSTIN TX 787584497 

3 VA POLYTECHNICAL 

INST & STATE UNIV 

DEPT OF ESM 

MWI-IYER 

K REIFSNIDER 

R JONES 

BLACKSBURG VA 24061-0219 

1 SOUTHWEST RSCH INST 

ENGR & MATL SCIENCES DIV 

J RIEGEL 

6220 CULEBRA RD 

PO DRAWER 28510 

SAN ANTONIO TX 78228-0510 

NO. OF 

COPIES ORGANIZATION 

ABERDEEN PROVING GROUND 

1 US ARMY MATERIEL 

SYSTEMS ANALYSIS ACTIVITY 

P DIETZ 

392 HOPKINS RD 

AMXSY TD 

APG MD 21005-5071 

1 DIRECTOR 

US ARMY RESEARCH LAB 

AMSRL OP Al’ L 

AJ?G MD 21005-5066 

90 DIR USARL 

AMSRL CI 

AMSRL CI S 

AMARK 

AMSRL CS IO FI 

M ADAMSON 

AMSRL SL BA 

AMSRL SL BL 

D BELY 

R HENRY 

AMSRL SL BG 

AMSRL SL I 

AMSRL WM 

J SMITH 

AMSRL WM B 

A HORST 

AMSRL WM BA 

D LYON 

AMSRL WM BC 

P PLOSTINS 

J NEWILL 

S WILKERSON 

A ZIELINSKI 

AMSRL WM BD 

B FORCH 

R FIFER 

R PESCE RODRIGUEZ 

B RICE 

AMSRL WM BE 

C LEVERITT 

AMSRL WM BF 

J LACETERA 

AMSRL WM BR 

C SHOEMAKER 

J BORNSTEIN 

41 
NO. OF 

COPIES ORGANIZATION 

ABERDEEN PROVING GROUND (CONT) 

AMSRL WM M 

D VIECHNICKI 

G HAGNAUER 

J MCCAULEY 

AMSRL WM MA 

L GHIORSE 

S MCKNIGHT 

AMSRL WM MB 

B FINK 

J BENDER 

T BOGETTI 

R BOSSOLI 

L BURTON 

K BOYD 

S CORNELISON 

P DEHMER 

R DOOLEY 

W DRYSDALE 

G GAZONAS 

S GHIORSE 

D GRANVILLE 

D HOPKINS 

C HOPPEL 

D HENRY 

RKASTE 

M KLUSEWITZ 

M LEADORE 

R LIEB 

E RIGAS 

J SANDS 

D SPAGNUOLO 

W SI’URGEON 

J TZENG 

E WETZEL 

A FRYDMAN 

AMRSL WM MC 

J BEAT-I-Y 

E CHIN 

J MONTGOMERY 

A WERECZCAK 

J LASALVIA 

J WELLS 

AMSRL WM MD 

W ROY 

S WALSH 

AMSRL WM T 

B BURNS 

M ZOLTOSKI 

NO. OF 

COPIES ORGANIZATION 

ABERDEEN PROVING GROUND (CON-I-) 

AMSRL WM TA 

W GILLICH 

T HAVEL 

J RUNYEON 

M BURKINS 

E HORWATH 

B GOOCH 

W BRUCHEY 

M NORMANDIA 

AMRSL WM TB 

D KOOKER 

I’ BAKER 

AMSRL WM TC 

R COATES 

AMSRL WM TD 

A DAS GUF’TA 

T HADUCH 

T MOYNIHAN 

F GREGORY 

M RAFI-ENBERG 

M BOTELER 

T WEERASOORIYA 

D DANDEKAR 

A DIETRICH 

AMSRL WM TE 

A NIILER 

J POWELL 

AMSRL SS SD 

H WALLACE 

AMSRL SS SE DS 

R REYZER 

R ATKINSON 

42 
NO. OF 

COPIES ORGANIZATION 

1 LTD 

R MARTIN 

MERL 

TAMWORTH RD 

HERTFORD SG13 7DG 

UK 

1 SMC SCOTLAND 

PWLAY 

DERA ROSYTH 

ROSYTH ROYAL DOCKYARD 

DUNFERMLINE FIFE KY 112XR 

UK 

1 CIVIL AVIATION 

ADMINSTRATION 

T GOTTESMAN 

PO BOX 8 

BEN GURION INTERNL AIRPORT 

LOD 70150 

ISRAEL 

1 AEROSPATIALE 

S ANDRE 

A BTE CC RTE MD132 

316 ROUTE DE BAYONNE 

TOULOUSE 31060 

FRANCE 

1 DRA FORT HALSTEAD 

P N JONES 

SEVEN OAKS KENT TN 147BP 

UK 

1 DEFENSE RESEARCH ESTAB 

VALCARTIER 

F LESAGE 

COURCELETTE QUEBEC 

COA IRO 

CANADA 

1 SWISS FEDERAL ARMAMENTS 

WKS 

W LANZ 

ALLMENDSTRASSE 86 

3602 THUN 

SWITZERLAND 

NO. OF 

COPIES ORGANIZATION 

1 DYNAMEC RESEARCH AB 

AKE PERSSON 

BOX 201 

SE 15123 SODERTALJE 

SWEDEN 

1 ISRAEL INST OF 

TECHNOLOGY 

S BODNER 

FACULTY OF MECHANICAL 

ENGR 

HAIFA 3200 

ISRAEL 

1 DSTO 

WEAPONS SYSTEMS DMSION 

N BURMAN RLLWS 

SALISBURY 

SOUTH AUSTRALIA 5108 

AUSTRALIA 

1 ECOLE ROYAL MILITAIRE 

E CELENS 

AVE DE.LA RENAISSANCE 30 

1040 BRUXELLE 

BELGIQUE 

1 DEF RES ESTABLISHMENT 

VALCARTIER 

A DUPUIS 

2459 BOULEVARD PIE XI NORTH 

VALCARTIER QUEBEC 

CANADA 

PO BOX 8800 COURCELETTE 

GOA IRO QUEBEC 

CANADA 

1 INSTITUT FRANC0 ALLEMAND 

DE RECHERCHES DE SAINT 

LOUIS 

DE M GIRAUD 

5 RUE DU GENERAL 

CASSAGNOU 

BOITE POSTALE 34 

F 68301 SAINT LOUIS CEDEX 

FRANCE 

1 ECOLE POLYTECH 

J MANSON 

DMX LTC 

CH 1015 LAUSANNE 

SWITZERLAND 

43 
NO. OF 

COPIES ORGANIZATION 

1 TN0 DEFENSE RESEARCH 

R IJSSELSTEIN 

ACCOUNT DIRECTOR 

R&D ARMEE 

PO BOX 6006 

2600 JA DELFT 

THE NETHERLANDS 

2 FOA NATL DEFENSE RESEARCH 

ESTAB 

DIR DEF’T OF WEAPONS & 

PROTECITON 

B JANZON 

R HOLMLIN 

S 172 90 STOCKHOLM 

SWEDEN 

2 DEFENSE TECH & PROC AGENCY 

GROUND 

I CREWTHER 

GENERAL HERZOG HAUS 

3602 THUN 

SWITZERLAND 

1 MINISTRY OF DEFENCE 

RAFAEL 

ARMAMENT DEVELOPMENT 

AUTH 

M MAYSELESS 

PO BOX 2250 

HAIFA 31021 

ISRAEL 

1 TN0 DEFENSE RESEARCH 

I H PASMAN 

POSTBUS 6006 

2600 JA DELFT 

THE NETHERLANDS 

1 B HIRSCH 

TACHKEMONY ST 6 

NETAMUA 42611 

ISRAEL 

1 DEUTSCHE AEROSPACE AG 

DYNAMICS SYSTEMS 

M HELD 

PO BOX 1340 

D 86523 SCHROBENHAUSEN 

GERMANY 

44 
REPORT DOCUMENTATION PAGE Form Approved 

OMB No. 0704-0188 

Public reporling burden for this collection Of information is estimated to average 1 hour per response. including the time for reviewing instrwtions, searching existing data souru)s. 

gathering and maintaining the data needed. and completing and reviewing the collection of information. Send comments regarding this burden estfmate or any other aspect of this 

colktion of information. including Suggestions for reducing this burden. to Washington Headquarters 5wAces. Directorate for Information Operations and Reports, 1215 Jefferson 

Davis Hiqbwav. Suite 1204 Arlinqton. VA 222024302. and to the OMce of Manaqement and Budqet. Papemork Reduction PmiectfOlM4158~. Washington. DC 20503. 

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED 

January 2002 Final, January 1997 - January 1998 

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS 

622618.H80 

Thermochemical Response of Vinyl-Ester Resin 

6. AUTHOR(S) 

Bruce K. Fink, Travis A. Bogetti, Molly A. Stone,* and John W. Gillespie, Jr.* 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS 8. PERFORMING ORGANIZATION 

REPORT NUMBER 

U.S. Army Research Laboratory ARL-TR-2653 

ATTN: AMSRL-WM-MB 

Aberdeen Proving Ground, MD 2 10055069 

3. SPONSORlNGlMONlTORlNG AGENCY NAMES(S) AND ADDRESS lO.SPONSORINGIMONlTORlNG 

AGENCY REPORT NUMBER 

II. SUPPLEMENTARY NOTES 

‘University of Delaware, Newark, DE 197 16 

l2a. DlSTRlBUTlONlAVAlLABlLlTY STATEMENT 12b. DISTRIBUTION CODE 

4pproved for public release; distribution is unlimited. 

13. ABSTRACT(Maximum 200 words) 

This report presents the thermochemical characterization of Dow Derakane 41 l-C50 commercial vinyl-ester resin 

at low temperatures (2OO-40 “C). Differential scanning calorimetry (DSC) and torsional braid analysis (TBA) are the 

experimental techniques used to characterize the material behavior. The cure kinetics are studied using DSC and are 

modeled using a modified autocatalytic equation with a maxinnmr degree of cure term. Also, the effect of inhibitors 

in the resin system is accounted for by an inhibitor depletion model. A time-temperature-transformation diagram is 

constructed for the material by measuring the times to gelation and vitrification using TBA. The glass transition 

temperature (Ts) is also characterized using the TBA and related to the degree of cure. It was found that the T, and 

the degree of cure do not exhibit a linear relationship for this resin system The fmdings presented in this work 

provide information for accurate cure modeling and process simulation of vinyl-ester materials. 

4. SUBJECT TERMS 15. NUMBER OF PAGES 

:omposites, vinyl ester, torsional braid analysis, differential scanning calorimetry 51 

16. PRICE CODE 

7. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT 

OF REPORT OF THIS PAGE OF ABSTRACT 

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED UL 

ISN 7540-01-280-5500 

45 Standard Form 298 (Rev. 2-89) 

Prescribed by ANSI Std. 239-18 298-102 
INTENTIONALLYLEFTBLANK. 

46