bluuebunny/crossref_metadata_2025 huggingface dataset:
The mass loss mechanisms of polymers in a radio frequency induced atomic oxygen environment
Authors: Whitaker A. F. , Jang B. Z.
Published: April 2003

The effects of atomic oxygen on several classes of polymers were investigated. Particular attention was directed to the determination of erosion or mass loss mechanisms in relation to the physical and chemical structures of polymers. Nineteen polymeric materials were exposed to a thermal atomic oxygen environment at fluxes of 1022 atoms/m2−sec. Bulk material temperatures were maintained at 10, 45, and 75°C During exposure. Mass loss rate, which was characteristic of the type of polymer, was proportional to the exposure area and was linear in time for most polymers except for Mylar, which produced a shielding high temperature ash. The mass loss rate for the atomic oxygen degradation of polymers was related to the bond strength of the polymer structure and to the shielding effect of pendant structures. This degradation process was strongly dependent on polymer temperature. Activation energies ranged from 1 to 48 KJ / mole and were found to be related to gaseous diffusion in polymers. Frequency factors were proportional to activation energies. Activation energies were found to increase with increased mol wt and crosslinking. An equation was developed relating exposure area, atomic oxygen flux, frequency factor, and activation energy to the rate of polymer mass loss. © 1993 John Wiley & Sons, Inc.
A new modification method of exploded lignin for the preparation of a carbon fiber precursor
Authors: Sudo K. , Shimizu K. , Nakashima N. , Yokoyama A.
Published: April 2003

A lignin‐pitch for carbon fiber was prepared in a high yield from exploded lignin on phenolysis followed by heat treatment under a vacuum. The lignin‐pitch had an excellent spinnability in the melt state to form a fine filament. The green fibers were easily made infusible when heated in air at a relatively high heating rate (15‐60°C/h). The lignin‐based carbon fiber was produced in 43.7% of yield based on a starting material. The tensile strength was more than 400 MPa, indicating that the lignin‐based carbon fiber is classified into a general purpose grade. © 1993 John Wiley & Sons, Inc.
Ionomer studies of polyethylene–acrylic acid copolymer. I. Fiber preparation and properties
Authors: Broughton Roy M. , Hall David M.
Published: April 2003

Two EAA (Ethylene/acrylic acid) copolymers from Dow Chemical Company have been studied. Primacor resin (5980), having a mol wt of about 30,000 and an acrylic acid content of 19.2%, was converted into 10 and 20 denier per filament fibers to create a high surface area. Cold drawing and use of a fiber lubricant helped prevent sticking and blocking during spinning. The fiber was optimally swollen in a 0.5 N caustic at 55°C to produce an ion exchange fiber. Primacor resin (5980) in pellet form was reacted with alkali and was subsequently hammermilled into an ion exchange porous particulate. Physical and chemical properties, such as thermal properties, swelling, cation exchange activity and selectivity, tensile and elongation properties, among others, were determined on the fiber before and after conversion to specific metal (cationic) forms. The swollen fibers appeared to have more cation binding capacity than hammermilled pellets. The EAA polymers were colored by some metal cations. Some metal cations could be preferentially removed from solutions of mixed cations. Most fibers were weak, even after exchanging with multivalent ions, and did not have a precise melting point. Fiber tension and solution pH during the cationic exchange had an effect on the cation uptake, as well as on the physical properties obtained. © 1993 John Wiley & Sons, Inc.
Synthesis of polyester pigment binders containing dimethyl 2,2‐dimethyl‐4‐methylene glutarate
Authors: Lin J. C. , Carlson G. M. , Abbey K. J. , Trumbo D. L.
Published: April 2003

Low molecular weight oligomers of dimethyl 2,2‐dimethyl‐4‐methylene glutarate and neo‐pentyl glycol have been synthesized. These oligomers were chain‐extended with select diacids and diols to polyesters that were used as pigment binders in paint formulations. Such paints were shown to possess superior detergent resistance when compared to paints formulated using pigment binders that did not contain dimethyl 2,2‐dimethyl‐4‐methylene glutarate. © 1993 John Wiley & Sons, Inc.
Functional polymers for colloidal applications. IV. Aggregate formation of lipophile‐grafted water‐soluble copolymers in aqueous solutions
Authors: Kuo Ping‐Lin , Hung Min‐Nan
Published: April 2003

A water‐soluble styrene–maleic anydride copolymer (SMA) is derivatized with different lipophilic groups, butylamine and dodecylamine, with different degrees of substitution (5, 15, and 30%). These lipophile‐grafted SMAs are water‐soluble, and their solutions are transparent. A plot of I1/I3 as a function of polymer concentrations indicates the extent of aggregate formation. Surface tension methods also verify the existence of aggregates. It is found that the aggregates begin to form at concentrations below that of the polymer transfer to the air–water interface. The plots of I1/I3 as a function of polymer concentrations for SMAs of different molecular weights derivatized with different lipophile with varying degrees of substitution show that the polymers with a higher degree of substitution and lower molecular weights aggregate at lower concentrations. Polymers substituted by butylamine form aggregates at a very high concentration, independent of the degree of sub‐stitution. These phenomena are interpreted in terms of hydrophobic interactions as in micelles formed from surfactants. The higher degree of dodecyl‐substituted SMA solubilizes pyrene at higher concentrations, and these pyrene solubilized solutions show pyrene excimer emission spectra. These emission spectra are used to characterize the relative size and hydrophobicity of aggregates. © 1993 John Wiley & Sons, Inc.
Tensile retraction measurements. V. The effect of carbon black on the cross‐link density of cured rubber
Authors: Hergenrother William L. , Doshak John M.
Published: April 2003

Tensile retraction measurements have been made on the same SBR filled with 50 phr of 10 different carbon blacks. The slopes and intercepts determined from the plots against λmax were determined in three different elongation ranges. These carbon blacks were chosen to have a variety of different surface areas and structures such that the influence of these features on the slopes and intercepts could be measured. The tensile retraction parameters determined were also evaluated at elevated temperatures and Arrhenius plots were made. The activation energies calculated from these plots showed that the structure and surface area of the carbon blacks had no effect on the process being measured. A series of different molecular weight SBRs were also made by anionic techniques to have 0, 1, and 2 tributyltin end groups. The changes in the constants determined from tensile retraction measurement on these cured filled stocks were explained in terms of the number of loose end groups still present after reaction with the carbon black. © 1993 John Wiley & Sons, Inc.
Gas transport properties of polycarbonate–polyurethane membrance
Authors: Cao N. , Pegoraro M. , Bianchi F. , Di Landro L. , Zanderighi L.
Published: April 2003

Polyurethanes (PU) were prepared using polymeric diols, containing polar groups, as OC(O)O(carbonate) groups, carbonate and ether (O) groups, or carbonate and ester groups [C(O)O]. PUs were prepared by the prepolymer two‐step technique using ethyl acetate (EA) as the solvent; the diol was reacted at about +80°C with TDI (ratio 1:2) to give the prepolymer terminated with NCO, which was then cross‐linked with triisopropanolamine (TIPA). The membranes were prepared using a Gardner knife and were characterized by differential thermal analysis (DSC). Most of the polymers prepared from low and medium molecular weight diols were amorphous and elastomeric at the temperature of gas transport measurement (35°C). The permeabilities (P) and the diffusion coefficients (D) of different gases (O2, N2, CO2, CH4, CO) were measured by a modified Lyssy apparatus, the solubility coefficient (S) was also calculated. The water‐vapor transport properties D and S were measured according to ASTM. Diffusivity data follow the Fujita model and the solubility coefficients the regular solution theory, as developed by Prausnitz and Shair. © 1993 John Wiley & Sons, Inc.
Mechanical and thermal behavior of cotton cellulose graft‐copolymerized using hydroxyethyl methacrylate in presence of triethylene glycol dimethacrylate
Authors: Shukla S. R. , Athalye A. R.
Published: April 2003

UV‐radiation‐induced graft‐copolymerization of cotton cellulose was carried out with 2‐hydroxyethyl methacrylate (HEMA) in the presence of small amounts of triethylene glycol dimethacrylate (TEGDMA) using benzoin ethyl ether (BEE), uranyl nitrate (UN), and ceric ammonium nitrate (CAN) as photoinitiators. The presence of very small amounts of (TEGDMA) in the HEMA grafting bath led to great enhancement in the graft add‐on as compared to that obtained on the sodium hydroxide‐preswollen substrate. With increase in the graft add‐on, the breaking load of cotton decreased, whereas its thermal stability improved © 1993 John Wiley & Sons, Inc.
Transport of small molecules in polyolefins. II. Diffusion and solubility of irganox 1076 in ethylene polymers
Authors: Földes Enikő
Published: April 2003

Diffusion coefficient and solubility of Irganox 1076 antioxidant in different ethylene polymers (LDPE, LDPE/LLDPE blend, and EVA) were studied between 45 and 80°C. For correct evaluation of the results, physical characteristics of the polymers and the additive were determined as a function of temperature. Good correlation was found between the diffusion rate of the additive and the free volume of the noncrystalline phase in the polymer. Measured solubilities were much higher than reported in the literature. © 1993 John Wiley & Sons, Inc.
Development of polyurethane engineering thermoplastics. I. Preparation and structure
Authors: Frontini Patricia M. , Rink Marta , Pavan Andrea
Published: April 2003

Rigid, tough thermoplastic copolyurethanes were prepared by a prepolymer technique. The soft‐segment content was varied over the 5–30 wt%. Six stoichiometric formulations based on diphenylmethane 4,4′‐diisocyanate (MDI), one or two different polyetherglycols, and one or two chain extenders of different structure were examined to test the possibilities of varying the degree of crystallinity of the products. Despite their thermoplastic characteristics, the resulting products were insoluble in the solvents normally used for elastomeric polyurethanes. The influence of curing temperature upon crystallinity and degree of polymerization was analyzed. Phase‐structure analysis, performed by differential scanning calorimetry, dynamic‐mechanical thermal analysis, and wide‐angle X‐ray scattering revealed complex phase structures strongly dependent on previous thermal history. In any case, the soft segments appear to constitute a dispersed phase in a rigid amorphous or semicrystalline matrix. Some samples exhibited two hard‐segment glass transitions associated with the existence of a bimodal length hard‐segment distribution. X‐ray diffraction patterns suggested that more than one crystalline form was present in the crystalline phase. © 1993 John Wiley & Sons, Inc.
Preparation and properties of uniform beads based on macroporous glycidyl methacrylate–ethylene dimethacrylate copolymer: Use of chain transfer agent for control of pore‐size distribution
Authors: S̆migol Vladimír , S̆vec Frantis̆ek
Published: April 2003

Poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) beads were prepared by both standard suspension polymerization and suspension polymerization in which the suspension of monodispersed droplets of the polymerization mixture was prepared by swelling of the shape‐template polymer particles with porogen diluents and monomers. The effect of bu‐tanethiol, a chain‐transfer agent in radical polymerization, on pore‐size distribution, specific surface area, and chromatographic properties was investigated and the mechanism of its action explained. The synergic effects of the chain transfer, cross‐linking monomer concentration, and content of porogenic diluent were documented. © 1993 John Wiley & Sons, Inc.
The effect of chemical composition of interphase on dispersion of cellulose fibers in polymers. I. PVC‐coated cellulose in polystyrene
Authors: Gatenholm P. , Bertilsson H. , Mathiasson A.
Published: April 2003

Cellulose fibers surface‐coated with butyl benzyl phthalate (BBP)‐plasticized PVC were evaluated as a reinforcement in thermoplastic matrices. Coated fibers were agglomerated during compounding with polypropylene (PP) and polyethylene (PE). However, an excellent dispersion and improved processability were achieved in polystyrene (PS). Melt rheology was also seen to be affected by fiber coating, and viscosity was lower for coated fibers. Fiber coatings seem to lubricate the blending process as well as to protect fiber from damage during processing. Fiber length was unaffected during treatment when coated fibers were used, as shown by microscopic investigation of extracted fibers, whereas the length of untreated fibers was reduced during processing. Introducing surface‐coated fibers into PS resulted in an increased elongation at break and improved impact strength of composites. The pullout of the fibers is suggested to be responsible for both improvements. The interphase achieved in PS with PVC/BBP‐coated fibers was simulated with PS/PVC/BBP blends. From DSC and DMTA, it was shown that BBP is a cosolvent for PS and PVC and that a single‐phase material was achieved at the relevant concentrations, which also was confirmed by optical clarity. © 1993 John Wiley & Sons, Inc.
Polyamine‐modified urea–formaldehyde‐bonded wood joints. III. Fracture toughness and cyclic stress and hydrolysis resistance
Authors: Ebewele Robert O. , River Bryan H. , Myers George E.
Published: April 2003

The objective of this study was to improve the durability and stability of urea–formaldehyde‐bonded wood products by decreasing the internal stress developed during the resin cure and by improving the ability of the cured system to withstand cyclic stresses. Urea–formaldehyde resins were modified either by incorporating urea‐capped di‐and trifunctional amines into the resin structure or by using the hydrochloride derivatives of some of these amines as the curing agent, or by both methods. This study supplements our previous work by examining the effects of additional amines and subjecting bonded products to additional testing. Solid wood joints bonded with a variety (7 of 15) of modified adhesives had resistance to cyclic stress superior compared to that of joints bonded with unmodified urea–formaldehyde adhesive; at least three of the modified adhesives approached the behavior of phenol–formaldehyde‐bonded joints. Resistance to moist heat aging, although still inferior to that of phenol–formaldehyde‐bonded joints, was significantly improved for joints bonded with modified adhesives over joints made with unmodified resins. The fracture behavior of joints made with modified adhesives was different from that of joints made with unmodified resins. The fracture energy was greater for joints made with three of four modified adhesives than for joints made with unmodified resins. Modified adhesives produced particleboards made with enhanced cyclic stress resistance. Formaldehyde emission from particleboards made with resins modified with urea‐terminated amines was less than emission from boards made with unmodified resins. However, emissions from particleboards made with amine hydrochlorides were not improved compared to those from boards made with an ammonium chloride curing agent. © 1993 John Wiley & Sons, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Difurfuryl diisocyanates: New adhesives derived from renewable resources
Authors: Holfinger Michael S. , Conner Anthony H. , Lorenz Linda F. , Hill Charles G.
Published: April 2003

The syntheses of difurfuryl diisocyanates [e.g., ethylidenebis (2,5‐furandiylmethylene) diisocyanate (EDFI)] have been reported in the literature. Difurfuryl diisocyanates are structurally similar to diphenylmethane diisocyanate (MDI), which has proven to be an excellent adhesive for bonding wood composites. The MDI regin is synthesized from petroleum‐derived chemicals; the EDFI resin is synthesized from biomass‐derived chemicals. In this study, the mechanical properties of aspen flakeboards bonded with MDI and EDFI are compared. In general, results show that the strength properties of flakeboards bonded with MDI are only marginally better than those bonded with EDFI. Because EDFI is more viscous than is MDI less than optimum atomization of the EDFI resin during spraying of the flakes is believed to be largely responsible for the differences in strength property values. The dry internal bond strength values of flakeboards bonded with MDI (1.33 MPa; 193 lb/in.2) at 3% resin content are significantly greater than the 0.41 MPa (60 lb/in.2) required by the American National Standards Institute (ANSI/A208.1) for type‐2 medium‐density particleboard. © 1993 John Wiley & Sons, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Study of the dispersion of low‐density polyethylene additive masterbatches in polyolefins
Authors: Ogbobe O.
Published: April 2003

Light Microscopy, X‐ray microradiography, and ultraviolet microscopy have been used to examine pigment dispersion in low‐density polyethylene pigment masterbatches and polyolefin/low‐density polyethylene additive masterbatch extrudates. The results obtained show that the dispersion of pigment additives in the low‐density polyethylene masterbatches studied were very poor. Also, the degree of dispersion of low‐density polyethylene pigment and ultraviolet masterbatches depend on the melt‐flow‐index of high‐density polyethylene. Blend is poor because of the two‐phase nature of the mix. © 1993 John Wiley & Sons, Inc.
Improved adhesion strength between aluminum and ethylene copolymers by hydration of the aluminum surface
Authors: Strålin Anders , Hjertbergc Thomas
Published: April 2003

By immersing aluminum in boiling water, a hydroxyl‐covered pseudoboehmite layer is formed on the aluminum surface. The adhesion strength between aluminum foils, hydrated in boiling water for short times, and ethylene copolymers, with vinyl acetate, n‐butyl acrylate, and acrylic acid, was examined. The laminates were obtained by pressing with 1.2 MPa at 250°C and the peel strengths were measured by a T‐peel test. By hydrating the aluminum foils, the adhesion strength was doubled for the ester copolymers, while a moderate effect was observed for the acrylic acid copolymer. To understand the adhesion mechanism, the chemical and topographic transformations were followed, using FTIR, SEM, TGA, and BET surface‐area analysis. The adhesion mechanism was found to depend on many factors, such as mechanical effects and increased surface area, due to the porosity of the hydrated film formed. The improved adhesion after hydration of the aluminum can also be explained by the fact that new, stronger interactions are formed. A carboxylate formation of carboxylic acid groups and a catalyzed hydrolysis reaction of the ester bond at the interface is also proposed. These reactions change the functionality on the polymer surface and the formation of stronger bonds between the materials is possible. © 1993 John Wiley & Sons, Inc.
Morphology and performance of polysulfone hollow fiber membrane
Authors: Lee Soon Hong , Kim Jae‐Jin , Kim Sung Soo , Kim Un Young
Published: April 2003

Polysulfone hollow fiber membranes were prepared via the dry‐wet spinning process from dope solutions comprised of polysulfone, n‐methyl‐2‐pyrrolidone, polyvinyl‐2‐pyrrolidone, and dodecylbenzene sulfonic acid, sodium salt. Morphology and performance of the membranes were affected by the compositions of coagulant and dope solution. Pore size and the water flux of the membrane increased by the addition of dodecylbenzene sulfonic acid, sodium salt to water in the coagulation bath, due to the changes of physicochemical properties of the outer coagulant. Addition of dodecylbenzene sulfonic acid, sodium salt to the dope solution also increased the pore size. The absence of polyvinyl‐2‐pyrrolidone, the pore forming agent, in the dope solution resulted in a remarkable decrease of pore size of the membrane. The distance between the spinneret and coagulation bath affected the membrane structure and performance. The membranes prepared in this study were suitable for hemofiltration in terms of molecular weight cut‐off characteristics. © 1993 John Wiley & Sons, Inc.
The mechanical properties of short fiber‐styrenic block copolymer composites
Authors: Ashida Michio , Guo Wuyun
Published: April 2003

The effect of fiber loading, fiber length, matrix type, and interface adhesion on mechanical properties of PET short fiber‐styrenic block copolymer TPEs, SIS, and SBS, was investigated. A strong bonding between PET fiber and TPE was obtained by surface treatment of TPE with isocyanate in toluene solution. The stress of the composites, filled with treated fiber, increased with increasing strain by two steps; the modulus for the first step was higher than the one for the second step, and the composites yielded obviously at about 50% strain, with higher stress than that of matrix TPE. With increasing fiber loading and fiber length, the modulus for the first step and the yield stress increased, but the yield elongation decreased. It seems that the matrix elastomer underwent most of the deformation and that the filled fiber underwent large internal stress with little deformation during extension of the composite, which may be an important phenomenon to influence short fiber reinforcement. The stress softening of composites showed a somewhat larger decreased rate than that of the matrix with repeated stress‐strain cycles, and the stress softening in the first cycle increased linearly with increasing fiber loading and increased in an S shape with increasing fiber length. In comparison with the SIS elastomer, the hysteresis of the SBS elastomer showed a big residual strain after the first elongation of 30%, and its retraction and subsequent re‐extension curves were obviously different from the extension curve, which was considered to be due to the destruction of parts of the styrene hard domai in SBS. The stress softening of the composites was influenced by the matrix elastomer, as well as by the loading fiber. The interface separation around the end of a fiber under large strain, and the breaking and restructuring of hard domain in the matrix, were considered to be important sources of softening of the composite. © 1993 John Wiley & Sons, Inc.
Synthesis and photoconductivity study of phthalocyanine polymers. III. PVK‐CuPC(NO2)2
Authors: Chen Hong‐Zheng , Wang Mang , Feng Lin‐Xian , Yang Shi‐Lin
Published: April 2003

Cu‐dinitro‐diamine phthalocyanine was synthesized, the corresponding diazonium salt was reacted with vinylcarbazole (VK), and a novel polyvinylcarbazole (PVK) ‐bonded CuPc(NO2)2 (I) was synthesized. The chemical structure of polymer (I) is identified by elemental analysis and IR and UV / VIS spectroscopy. Polymer (I) contains about 21 mol % CuPc(NO2)2 rings that are covalently bonded to PVK. Polymer (I) shows good pho‐toconductivity, which is much better than that of the corresponding phthalocyanine monomers. The influence of the interface layer and the charge‐transportation material on the photoconductivity of polymer (I) is also discussed. © 1993 John Wiley & Sons, Inc.
Characterization of surface properties of plasma‐polymerized fluorinated hydrocarbon layers: Surface stability as a requirement for permanent water repellency
Authors: Wang H. Z. , Rembold M. W. , Wang J. Q.
Published: April 2003

Plasma polymers were deposited on poly (ethylene terephthalate) (PET) substrates using fluorocarbons such as CF4, C2F6, C3F6, C4F8, and mixtures thereof with CH4. The fluoro‐carbons selected were of saturated structure (CF4, C2F6), unsaturated structure (C3F6), and cyclic structure (C4F8). The addition of CH4 to any of the fluorocarbons caused a deposition of plasma polymers. However, the deposition rate strongly depended on the amount of CH4 added. A fluorocarbon‐dominated feed, i.e., fluorocarbons with 17 mol % CH4, was found to lead to an effective deposition of plasma polymers, whereas a CH4‐rich feed, i.e., fluorocarbons with 67 mol % CH4, led to an ineffective polymer deposition. For the same molar composition of fluorocarbon/CH4, polymer deposition depended on the fluorocarbon structure. It decreases in the order C3F6> C4F8> C2F6> CF4. Elemental analysis showed an atomic ratio F/C of 2.2 and 2.3 for C3F6 and C4F8 plasma polymer powder, respectively, whereas the corresponding values obtained from X‐ray photoelectron spectra (XPS) surface analysis of films showed 1.5 and 1.6, respectively. An explanation could lie in bulk and surface differences of the deposited layers. Contact‐angle measurements revealed that among the monomers employed only C3F6 with 17 mol % CH4 resulted in a relatively stable, hydrophobic surface. © 1993 John Wiley & Sons, Inc.
Syntheses and electric conductivities of poly (methyl vinyl ketone–co–maleic anhydride)s reacted with phosphorus oxychloride
Authors: Kim Dae Young , Kim Yoon Seok , Ha Chang Sik , Cho Sung Jin , Park Dong Kyu , Cho Won Jei
Published: April 2003

Electric conductivity of poly (methyl vinyl ketone‐co‐maleic anhydride) (poly (MVK‐co‐MAH)) reacted with phosphorus oxychloride was investigated. It was found that conductivities were strongly dependent on the POCl3 treatment time and concentration for poly (MVK‐co‐MAH), but were not appreciably affected by the mol fraction of [MAH] and copolymerization temperature when the precursor copolymer was obtained. The conductivities of the poly (MVK‐co‐MAH)s treated with POCl3 were of the order of 10‐6 to 10‐9S cm‐1. The conductivity of the poly (MVK‐co‐MAH) increased with the treatment time and concentrations of POCl3. © 1993 John Wiley & Sons, Inc.
Multistage melt polymerization of bisphenol‐A and diphenyl carbonate to polycarbonate
Authors: Kim Yangsoo , Choi Kyu Yong
Published: April 2003

A multistage melt polycondensation of bisphenol‐A and carbonate has been studied experimentally using LiOH·H2O catalyst. The reaction process consists of batch and semi‐batch periods with different temperature and pressure conditions. It was observed that a small amount of diphenyl carbonate lost from the reaction mixture by vaporization had little effect on the molecular weight in the batch reaction period but the efficiency of subsequent low‐pressure semibatch polycondensation was affected by the change in the mol ratio of the phenyl carbonate group to the hydroxyl end group. A molecular species model developed for the multistage process was used to analyze the kinetics of the polycondensation process. The composition of the reaction mixture was analyzed of HPLC and compared with model simulations. In particular, the effect of evaporative loss of diphenyl carbonate on the progress of reaction is discussed in detail. © 1993 John Wiley & Sons, Inc.
Peroxide modification of linear low‐density polyethylene: A comparison of dialkyl peroxides
Authors: Bremner Tim , Rudin Alfred
Published: April 2003

A commercial‐grade LLDPE resin was cross‐linked using three different dialkyl peroxides, at three different concentrations. The peroxides were ranked in order of their Cross‐linking efficiency and their effectiveness at increasing the storage modulus of the virgin resin at the cure temperature. The chemical mechanism by which the cross‐linking occurs is shown to be closely related to the changes in concentrations of reactive vinyl species on the polyethylene molecules, which follows well with proposed mechanisms of previous publications. Finally, a direct relationship is shown to exist between the rate of peroxide decomposition and the rate of increase in storage modulus of the rubbery modified resin during the curing reaction. © 1993 John Wiley & Sons, Inc.
Kinetics and characterization of the process‐zone evolution in polycarbonate
Authors: Kim A. , Garrett L. V. , Bosnyak C. P. , Chudnovsky A.
Published: April 2003

The process‐zone evolution strongly influences the crack growth of polycarbonate. A methodology for determination of the kinetics of the process‐zone evolution by decoupling these two processes was developed. This was achieved using constant displacement (stress‐re‐laxation) conditions under which the crack length remained constant. The morphology of the process zone was characterized using optical microscopy of cross sections and fracture surfaces produced with liquid nitrogen. The kinetics of process‐zone evolution and stress relaxation were monitored and analyzed. The kinetics vary significantly with the level of displacement imposed. Thus, the challenge remains to construct a master curve for the kinetics. © 1993 John Wiley & Sons, Inc.
Molecular changes of PET yarns during stretching measured with rheo‐optical infrared spectroscopy and other techniques
Authors: Van Den Heuvel C. J. M. , Heuvel H. M. , Fassen W. A. , Veurink J. , Lucas L. J.
Published: April 2003

A method has been developed for measuring infrared spectra during the mechanical deformation of yarns. This rheooptical technique was applied to study the molecular processes that take place along the stress‐strain curve of PET yarns. The results were combined with data obtained from size exclusion chromatography (SEC) and tensile measurements at elevated temperatures. The results indicate that the first modulus maximum marks the breakdown of the amorphous entanglement network and the start of molecular uncolling by gauche → trans transitions. In addition, stress develops on the crystals and particularly on tie molecules with a short contour length in the amorphous domains. Ultimately, molecular fracture of taut‐tie molecules causes the modulus to pass through a second maximum. The chain ends of broken molecules recoil by trans → gauche transitions. Local stress accumulation will lead eventually to yarn rupture. © 1993 John Wiley & Sons, Inc.
Preparation of quaternary ammonium resin by epoxy resin and tertiary amine and its electrodeposition properties
Authors: Yang Chin‐Ping , Ting Chih‐Yang
Published: April 2003

A quaternary ammonium‐containing cationic resin is prepared by the ring‐opening reaction of epoxy resin and tertiary amine with the presence of a proton donor. Its emulsion can form a uniform polymer film on the cathodic metal by electrodeposition. In this study, the reaction conditions to prepare the quaternary ammonium resin from epoxy resin and tertiary amine, and effects of different proton donors on this reaction, were examined by gel permeation chromatography and infrared. Meanwhile, distinctions of electrodeposition properties between the quaternary ammonium resin and the tertiary amine acid salt resin were considered. Finally, the electrodeposition mechanism of quaternary ammonium resin was also determined. The results show that the quaternary ammonium resin prepared by triethylamine (TEA) and Epon 1004 has better solubility and emulsification than the tertiary amine acid salt resin prepared by diethylamine (DEA) and Epon 1004. Rupture voltage of this quaternary ammonium resin was very low because it was prepared by full‐alkyl group tertiary amine. Therefore, this kind of quaternary ammonium resin was not suitable for use for the electrodeposition resin individually. But when this quaternary ammonium resin was added to the tertiary amine acid salt resin, the deposited yield was much increased. © 1993 John Wiley & Sons, Inc.
Effect of compatibility on heat capacity of molten polyblends
Authors: Wang Y. Z. , Hsieh K. H. , Chen L. W. , Tseng H. C.
Published: April 2003

The heat capacity and phase relation of polymer blends consisting of two homopolymers or a homopolymer with a block copolymer have been investigated by differential scanning calorimetry (DSC). Polystyrene (PS) and polybutadiene (BR) are the two homopolymers, while the styrene–butadiene–styrene (SBS) copolymer is employed as the block copolymer in this study. The heat capacity and specific volume of the PS and BR homopolymers increase with increasing temperature at a constant pressure. The heat capacity of styrenebutadiene (SBR) random copolymer, which is considered a miscible system, can be calculated by an additive rule from the addition of the styrene and butadiene segment number fractions in the random copolymer multiplied by the corresponding heat capacity of PS and BR homopolymers. However, the heat capacity of the immiscible system of the SBS triblock copolymer can be estimated by the addition of the two segment number fractions multiplied by the reciprocal of the corresponding heat capacity of the PS and BR homopolymers. The thermal and dynamic mechanical analysis data of the polyblend from the two PS and BR homopolymers both show a low degree of miscibility. A saturated solubility of the homopolymer dissolved in the SBS block copolymer is proposed and the purification of the styrene and butadiene phases in the SBS copolymer is observed as it blends with either PS or BR homopolymer. The heat capacity of polymer blends composed of two phases obey the principle of additivity from the weight fractions of the heat capacity of the corresponding individual phase. © 1993 John Wiley & Sons, Inc.
Mechanical properties of PET short fiber–polyester thermoplastic elastomer composites
Authors: Guo Wuyun , Ashida Michio
Published: April 2003

Presented in this paper is the investigation of the mechanical properties of PET short fiber‐polyester thermoplastic elastomer (Hytrel) composites and the discussion of the short fiber reinforcement of the composites. Excellent adhesion of PET fiber to Hytrel elastomer was obtained by treating with isocyanate in toluene solution. The Hytrel composites filled with treated fiber showed a similar tensile behavior, with higher values, to that for the matrix elastomer when fiber loading was less than 5 vol %. The composites loading fibers more than 5 vol % displayed an obvious yield phenomenon, and their yield elongation (between 30–40%) was greater than the fiber's break elongation, which suggested that extensibility of the fiber was quite different from that of the matrix. It is considered that the reinforcement of the short fiber mainly depends on the difference of extensibility between the fiber and the matrix because the difference directly affects the effective transference of the stress from matrix to fiber. The modified parallel model for Young's modulus and yield strength of the composite can be given by the following equations:

and

respectively, through introducing two effective deformation coefficients, α and β, to represent the extensibility of the fiber and the matrix respectively. The α obtained from the experimental results did not depend on fiber loading but increased with increasing fiber length, and the α for Young's modulus was larger than the one for yield strength, which suggests that α is a function of the strain of the composite and may decrease with increasing the strain, namely, the deformation difference between the fiber and the matrix increases when the strain increases. On the other hand, β is a function of α as:

For the Hytrel elastomer, the maximum of each succeeding stress–strain cycle coincided with the original stress–strain curve for elongations under 600%, but for the Hytrel composites such coincidence was limited to elongations under 30%. This may be caused by the reforming of crystallites in the stress‐softened Hytrel elastomer phase at high strain. © 1993 John Wiley & Sons, Inc.
Volatile compounds extracted from polypropylene sheets by hot water: Influence of the temperature of sheets injection
Authors: Rebeyrolle‐Bernard P. , Etiévant P.
Published: April 2003

The influence of the formulation of polypropylene (PP) on the organoleptic properties of the foodstuff in contact is of great importance for the quality of the product. A study was made on PP pellets degraded and not degraded and pointed out the presence and olfactive importance of volatile components extracted from PP pellets by hot water. Plastic packaging materials correspond to a further step of manufacturing: the injection step, and this is often conducted at high temperature. PP (not degraded) and PP‐CR (degraded) were transformed into sheets at several temperatures; Lickens–Nickerson extracts were made and allowed the quantification of volatile compounds already identified. A statistical analysis showed that temperature was a very significant parameter. An increasing injection temperature (275 or 300°C) creates increasing quantities of volatiles. This was well correlated with the sensory analysis made on the organic extracts of the sheets and also directly on molded cups. © 1993 John Wiley & Sons, Inc.
Native celluloses on the basis of two crystalline phase (Iα/Iβ) system
Authors: Wada Masahisa , Sugiyama Junji , Okano Takeshi
Published: April 2003

A survey by X‐ray diffractometry was carried out to confirm the two crystalline phase Iα/Iβ(triclinic/monoclinic) system of native celluloses. We have investigated cellulose samples from 12 different origins and measured the d‐spacings with reasonable precision. The samples were then subjected to the hydrothermal annealing that brings the cellulose crystals to the monoclinic type; d‐spacings were reevaluated afterward. From the statistical analysis using observed d‐spacings, all the cellulose samples were categorized into the two groups that coincide with the two crystalline phase systems: one is the algal‐bacterial type rich in triclinic phase and the other is the cotton‐ramie type of the monoclinic phase. © 1993 John Wiley & Sons, Inc.
IR studies of wood plastic composites
Authors: Khan Mubarak A. , Ali K. M. Idriss , Basu Subhash. C.
Published: April 2003

Wood plastic composites (WPC) of simul were prepared by gamma radiation using butylacrylate (BA) and methylmethacrylate (MMA) as the monomer and methanol as the swelling agent at 9:1 (v/v) ratio. IR spectra of simul, bulk polymer of BA (or MMA) film, and WPC of different polymer loadings ranging from 18 to 115% were studied. Increase of the characteristic peak intensity at 1735 cm−1 (CO vibration for acetyl groups) over that of 1620 cm−1 (conjugated aryl carbonyl groups) along with the increase of polymer loading of simul with the monomer indicates that the graft copolymerization took place between the monomer and the simul wood matrix. © 1993 John Wiley & Sons, Inc.
Thermal behavior of ungrafted and grafted bagasse and wood pulps
Authors: Kessira L. , Ricard A.
Published: April 2003

The effect of grafting of methyl methacrylate (MMA) and acrylonitrile (AN) on the thermal behavior of the pulp of sugar cane loaded with CaCO3 and the pulp of a broad‐leaved tree has been studied by thermal methods. Different experimental conditions of grafting AN onto the eucalyptus pulp have been used, including both water and organic solvent systems as the medium of reaction. To optimize the grafting of MMA onto wood pulp, the effect of pulp swelling and the contact time of the monomer with the pulp have been examined. Ungrafted as well as grafted cellulose samples with different levels of grafting were characterized by differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA). The CaCO3 filler makes the pulp of bagasse thermally more stable. The grafting of MMA onto the bagasse or the wood pulps improves their thermal stability. This is not the case for wood grafted with poly(AN). The thermal stability of the grafted and ungrafted samples varies after a few weight percent has been lost. The glass transition temperature (Tg) of the copolymers have been measured and they are in good agreement with the calculated data. © 1993 John Wiley & Sons, Inc.
Determination of PEG concentration in its aqueous solution using differential scanning calorimetry
Authors: Yamauchi T. , Hasegawa A.
Published: April 2003

The Freezing and melting behavior of aqueous poly(ethylene glycol) (PEG) solutions up to a concentration of 10% was examined using DSC. So long as the molecular weight of PEG is over 1000, the cooling and heating DSC curves have two peaks, which are attributed to freezable bound water and free water. The amounts of freezable bound water and nonfreezing water linearly increase with an increase of PEG concentration. Therefore, a method using DSC was proposed for determining the concentration of aqueous PEG solutions. Although PEG concentration can be determined by the heat of freezable bound water, the ratio of heat of freezable bound water to heat of free water is a better way to determine the concentration. © 1993 John Wiley & Sons, Inc.
Skin and layer formation in films prepared from carbohydrates, poly(ethylene‐co‐acrylic acid), and polyethylene
Authors: Swanson C. L. , Fanta G. F. , Salch J. H.
Published: April 2003

Cornstarch, a canary dextrin, and a maltodextrin were compared in films blown from carbohydrates compounded with poly(ethylene‐co‐acrylic acid) (EAA), low‐density polyethylene (LDPE), and aqueous ammonium hydroxide plasticizer. Dextrins or maltodextrins having dextrose equivalent values of one and greater caused dark‐colored films with caramel odors, probably due to Maillard reactions. Blown films with hydrophobic skins and water sensitive cores were produced with the dextrinized carbohydrates, but not from natural cornstarch. Water sensitivity of films containing the dextrinized carbohydrate was reduced by recycling the films through the blown film die. A mechanism for development of the skins is proposed, as is a method for preparing thin semipermeable membranes. © 1993 John Wiley & Sons, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Multifunctional epoxy resins
Authors: Choudhary Veena , Agarwal Seema , Varma I. K.
Published: April 2003

The curing behavior of epoxy resins prepared by reacting epichlorohydrin with 4,4′‐diaminodiphenyl methane (DADPM)/4,4′‐diaminodiphenyl ether (DADPE) or 4,4′‐diaminodiphenyl sulfone (DDS) was investigated using DDS and tris‐(m‐aminophenyl)phosphine oxide (TAP) as curing agents. A broad exothermic transition with two maxima were observed in the temperature range of 100–315°C when TAP was used as the curing agent. The effect of varying DDS concentration on curing behavior of epoxy resin was also investigated. Peak exotherm temperature (Texo) decreased with increasing concentration of DDS, whereas heat of curing (ΔH) increased with an increase in amine concentration up to an optimum value and then decreased. Thermal stability of the resins, cured isothermally at 200°C for 3 h, was investigated using thermogravimetric analysis in a nitrogen atmosphere. Glass fiber‐reinforced multifunctional epoxy resin laminates were fabricated and the mechanical properties were evaluated. © 1993 John Wiley & Sons, Inc.
Photocross‐linking of low‐density polyethylene. III. Supermolecular structure studied by SALS
Authors: Qu Bao Jun , Rånby Bengt
Published: April 2003

The supermolecular structure of photocross‐linked polyethylene (XLPE) has been studied by small‐angle light scattering (SALS). The data show that the spherulitic structure of XLPE gradually deteriorates with increasing degree of cross‐linking and increasing irradiation temperature from well‐developed spherulites to rodlike aggregates and disordered lamellar structures. A photocross‐linked sample of PE has lower crystallinity, smaller crystallites, and smaller spherulites than does the original sample. At high degrees of cross‐linking, the SALS patterns show little or no spherulitic structure. Results with photocross‐linked polyethylene demonstrate that the overall effect of cross‐linking on the morphological structure is similar to that of an increase in molecular weight of the polymer. © 1993 John Wiley & Sons, Inc.
Spin probe studies of nonsolvent penetration into polymer particle formed from poly(vinyl acetate) and poly(2‐ethylhexyl methacrylate)
Authors: Pekcan Önder , Demir Yusuf
Published: April 2003

Nonaqueous dispersion (NAD) of poly(vinyl acetate) (PVAc) particles sterically stabilized by poly(2‐ethylhexyl methacrylate) were examined by ESR spectroscopy after introduction of a trace quantity of a spin probe, 3‐carbomoyl‐2,2,5,5‐tetramethyl 3‐pyrolin‐1‐yloxy. ESR spectra were monitored as a function of temperature from ‐160 to 100°C. In spite of the complex morphology of the particle, it is found that the behavior of the probe in the NAD was essentially identical to that in a pure PVAc matrix. Solvent penetration into (NAD) particles were studied. These colloidal particles were exposed to a dilute solution of the spin probe, and the bimodal distribution of the ESR spectra of this probe molecule were carefully monitored as a function of time. Fickian‐type diffusion of spin probes into the particles was observed and a spherical model was employed to obtain the diffusion coefficients (D) in various solvents. D values were found around 10–15 cm2/s and were interpreted as the parameter, inversely proportional to the apparent viscosity of the environment inside the PVAc particle. The maximum amount of diffused solvent molecules (M∞) into the PVAc particle was found inversely proportional to polymer‐solvent interaction through the solubility parameters. © 1993 John Wiley & Sons, Inc.
Silane‐modified polyvinylimidazole(1) for corrosion protection on copper at elevated temperatures
Authors: Jang Jyongsik , Ishida Hatsuo
Published: April 2003

Silane‐modified N‐polyvinylimidazole [PVI(1)] copolymers have been synthesized from various mole ratios of γ‐methacryloxypropyltrimethoxysilane (γ‐MPS) and N‐vinylimidazole, VI(1). Fourier transform infrared reflection‐absorption spectroscopy (FTIR‐RAS) is used to investigate the modified PVI(1) on copper surfaces. The silane‐modified PVI(1) has good corrosion protection and adhesion promotion capabilities for copper substrate under severe environments. The relationship between coating thickness and corrosion protection is studied at elevated temperatures. The relationship between the mole ratio of comonomers and the corrosion processes of a copper surface has also been investigated at elevated temperatures. The corrosion protection improves drastically with increased VI(1) content. An adhesion study of the silane‐modified PVI(1) film on a copper surface is also carried out using the ASTM adhesive tape test. From the adhesion strengths between the modified PVI(1) films and copper surface, it has been observed that modified PVI(1) acts as an adhesion promoter and does not depend on the mole ratio of γ‐MPS/VI(1) within the range of this experiment. Good adhesion of an anticorrosion coating is important for the corrosion protection of a copper surface. © 1993 John Wiley & Sons, Inc.
Selective hydrogenation of olefinic bonds in styrene‐isoprene‐styrene triblock copolymer by palladium acetate catalyst
Authors: Bhattacharjee Susmita , Rajagopalan Padmavathy , Bhowmick Anil K. , Avasthi Bhola Nath
Published: April 2003

Homogeneous catalytic hydrogenation of styrene‐isoprene‐styrene triblock copolymer (SIS) has been carried out selectively at the carbon‐carbon double bond in the presence of palladium acetate catalyst under mild conditions. Degree of hydrogenation has been calculated with the help of infrared and nuclear magnetic resonance spectroscopic techniques. Almost 90 mol % complete hydrogenation has been achieved at 60°C under 1.4 MPa hydrogen pressure, 40 mg catalyst (for 2 g of polymer) in chloroform‐acetone solution for 1 h. © 1993 John Wiley & Sons, Inc.