bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface treatment of polymers. II. Effectiveness of fluorination as a surface treatment for polyethylene
Authors: Schonhorn H. , Hansen R. H. 
Published: April 2003

AbstractAn effective surface treatment for adhesive bonding of polyethylene has been developed. It involves exposing the polymer to an environment of elemental fluorine or fluorine diluted in argon. By this treatment, extensive fluorination of the surface region is effected. The fluorinated surface permits formation of strong adhesive joints by conventional adhesive bonding techniques even though the wettability of the new surface is similar to polytetrafluoroethylene. We believe that treatment of the polymer with elemental fluorine effectively eliminates the weak boundary layer associated with polyethylene by either crosslinking or by increasing the molecular weight in the surface region.
Solution polymerizations of epoxytetrahydrophthalic anhydride and its utilization in various epoxy systems
Authors: Cassidy P. E. , McCarthy D. K. 
Published: April 2003

AbstractSolution polymerization of epoxytetrahydrophthalic anhydride (ETHPA) has been thoroughly studied by using numerous solvents and catalysts. Products have been obtained in high yields, particularly when triethanolamine was the catalyst. This suggests that this catalyst should be considered for further applications utilizing ETHPA. However, the solution polymerization method cannot be used alone to define the effects of various catalysts on standard nonsolvated resin systems, because polymerization is greatly affected not only by the addition of solvent but also by the type of solvent. In addition, the action of the catalyst seems to depend greatly upon what solvent is employed. The reason for this dependence has not been established. The effects of the addition and reaction of ETHPA with commercial epoxy resin formulations have been investigated by means of heat distortion tests and differential thermal analyses. In most cases, although a moderate improvement was found in the thermal properties of the resins, occasional excellent results were obtained. A 10°C. increase in HDT is observed with a 2 wt.‐% addition of ETHPA for bisphenol A epoxy resin–bicyclic anhydride mixture. The degree of elevation of Tg and HDT with the addition of ETHPA obviously depends not only on the composition of the resin system but also on its cure temperature. A good correlation occurs between heat‐distortion temperatures and glass transition temperatures. Some few anomalous data, however, are found which point to the fact that further investigation is required before HDT and Tg can be interchanged without prior evidence of a definite relationship.
Reactions catalyzed by minerals. Part III. The mechanism of spontaneous interlamellar polymerizations in aluminosilicates
Authors: Solomon D. H. , Loft B. C. 
Published: April 2003

AbstractThe spontaneous polymerization of hydroxymethacrylate monomers by the layer aluminosilicate montmorillonite is reported. Saturation of montmorillonite by acrylic monomers gives interlayer complexes of three types, only one of which is susceptible to spontaneous polymerization. Electron‐donating sites situated within the silicate lamellae initiate the spontaneous polymerization which it is suggested proceeds by a mechanism involving radical‐anions. The results of this study together with those reported previously are used to explain the variety of effects noted when aluminosilicates are added to or heated with vinyl or acrylic monomers.
Stabilization of high‐density polyethylene
Authors: Rothstein Edwin C. 
Published: April 2003

AbstractSeveral types of antioxidants are evaluated in high‐density polyethylene for color and physical property stabilization during processing and thermal aging. A wide variety of evaluation tests are used and discussed. Heat‐ and light‐induced oxidation mechanisms are reviewed. Antioxidants such as octadecyl‐3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl) propionate and tetrakis[methylene 3‐(3′,5′‐di‐tert‐butyl‐4′‐hydroxy phenyl) propionate] methane were found to provide very high retention of physical properties, excellent initial color and color retention. Combinations of antioxidant‐ and ultraviolet light absorbers were evaluated for stabilizing high density polyethylene exposed to artificial light and outdoor weathering. The combination of octadecyl‐3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl) propionate and 2‐(2′‐5′‐di‐tert‐butyl‐2′‐hydroxy‐phenyl)‐5‐chlorobenzotriazole was found to be a very efficient stabilizer system. Polymer containing this stabilizer combination had excellent color stability and minimum crosslinking and embrittlement after Arizona weathering.
Diffusion of additives in polyolefins
Authors: Jackson R. A. , Oldland S. R. D. , Pajaczkowski A. 
Published: April 2003

AbstractA simple radio‐tracer method based on 14C is described for determining the diffusion coefficient of an additive in a polymer. Two theoretical models representing extreme cases for the diffusion system are discussed and shown to yield the same solution to within 10%. The diffusion coefficients of didodecyl 3,3′‐thiodipropionate, N‐octadecyldiethanolamine, and 1,1,3‐tri(2‐methyl‐4‐hydroxy‐5‐tert‐butylphenyl)butane migrating in polyethylene, polypropylene, and poly‐4‐methylpentene‐1 have been measured over temperature ranges of 50–80°C., within the range 20–200°C. In each case the variation of the diffusion coefficient D with temperature T can be represented by an Arrhenius equation D = D0 exp {‐E/RT}, where the activation energy E is virtually independent of the size and shape of the diffusing molecule. The activation energy depends upon the polymer and is about 12.5, 21, and 14.5 kcal./mole for polyethylene, polypropylene, and poly‐4‐methylpentene‐1, respectively.
Ceric ion‐induced redox polymerization of acrylonitrile on cellulose
Authors: Kulkarni A. Y. , Mehta P. C. 
Published: April 2003

AbstractThe ceric ion‐cellulose redox system has been studied for grafting acrylonitrile on cotton fibers. Grafting yields are very high as compared to the persulfate‐thiosulfate redox system reported earlier. Traces of copper sulfate in the reaction mixture do not increase grafting yields, unlike the persulfate‐thiosulfate system. The high polymerization rate on cotton fibers is shown to be due to the reducing action of cellulose and not to the large surface area of cotton fibers. The Ce+4 consumption during grafting is higher than during oxidation of cellulose, indicating formation of homopolymer during the grafting reaction. Studies on the consumption of Ce+4 by model compounds such as D‐glucose and α‐methyl‐D‐glucoside show that the hemiacetal group in D‐glucose is responsible for a faster rate of Ce+4 consumption. Formation of a Ce+4‐alcohol complex also contributes to the initial fast rate of Ce+4 consumption. Studies on the oxidation of cellulose by Ce+4 indicate that the initial oxidative attack occurs on carbon atom 2, with the formation of a >CO group. On further oxidation, cleavage of the C2‐C3 bond occurs as shown by the presence of glycol aldehyde determined chromatographically. Cellulose‐polyacrylonitrile grafts have been isolated by an acetolysis treatment followed by extraction with dimethylformamide. Number‐average molecular weights of the isolated fractions are approximately 50,000–55,000. A theoretical method to calculate the number‐average molecular weights, based on the PAN and the COOH contents of the grafted cellulose, is described.
Some viscoelastic properties of ABS polymer
Authors: Scalco E. , Huseby T. W. , Blyler L. L. 
Published: April 2003

AbstractThe discrete relaxation spectrum of an ABS (acrylonitrile–butadiene–styrene) polymer at 190°C. was calculated by using results from tensile relaxation moduli and the principle of reduced variables. The shift factor was found to conform well to the WLF equation, and the free volume fraction at Tg was calculated to be 0.026 in good agreement with the universal value. The values of the thermal expansion coefficient of free volume were calculated to be 9.8 X 10‐4 deg.−1 and 7.0 × 10−4 deg.−1, respectively, from the WLF coefficients and from dilatometric results. The width of the entanglement plateau of the relaxation spectrum was observed to be a factor of approximately 2 larger than that calculated from molecular weights between entanglement couplings determined either from rubber elasticity theory or from an assumed molecular model which discounts the presence of the butadiene in the ABS system. By using Pao's theory, flow curves at 190°C. were calculated both from the discrete relaxation spectrum and from the dynamic modulus. These curves were essentially identical. However, the stress values of these curves were found to be about a decade higher than those experimentally determined from capillary flow measurements. Nevertheless, the shapes of the curves are in good agreement, and an explanation is suggested for existing discrepancies. Flow instability, processing variables, and residual strains are discussed in light of the flow curves and the calculated recoverable shear strains.
Study of a heat‐resistant plastic laminate from the standpoint of a mechanical–chemical equation of state
Authors: Goldfein S. 
Published: April 2003

AbstractThe object of this study was to analyze the complex degradation history of a heat‐resistant epoxy resin laminate using the mechanical–chemical equation of state. A further object was to determine if weight‐loss measurements at elevated temperatures could be used to predict long‐term rupture strength. Master rupture curves drawn by using a second‐order parametric form of the equation of state largely clarified the anomalous behavior of the laminate. It was not found possible to predict the longterm mechanical properties from weight‐loss data although there was evidence of some correlation.
Equation of consumption rate of free‐radical vinyl polymerization. II
Authors: Sasaki Hideki 
Published: April 2003

AbstractThe vinyl polymerization reaction is a two‐molecule reaction. However, it is more convenient to use a specially defined rate constant than to use the general constant, because a new radical is formed instantaneously in the same radical compound when one monomer combines with an existing radical in a living polymer or an initiator radical. This special rate constant is named the propagation constant and is proportional to the concentration of monomer when the polymer is formed from a unit mole concentration of the initiator radical. The specific propagation constant is related to the concentration of monomers which react in unit time and unit concentration of monomer and radical. Arnett's experiments are discussed in terms of the equation formulated. The value of Δ[M]/([M]0·t) is found not to be a reaction rate but a value of ln [M]0/[M] when [M]0 – [M] is very small. Autoacceleration of the polymerization is found with high concentrations of monomer which yield an increase in the velocity of propagation and also at low concentrations of initiator, which cause prolongation of the propagation stage. When the concentration of initiator is high, this phenomenon does not take place until enough initiator is consumed and the necessary low initiator level is reached. The time required is called the induction period. The larger the polymer molecule is, the higher the viscosity becomes.
Factors affecting the strength of a polyhydroxy ether
Authors: Golden J. H. , Hazell E. A. , Wright H. 
Published: April 2003

AbstractThe effects of moisture content, aging, annealing, irradiation, temperature, and rate of testing on the tensile yield strength of the polyhydroxy ether derived from bisphenol A and epichlorohydrin are described and discussed. In particular, annealing at temperatures below Tg is shown to cause significant increases in strength which are associated with an endothermal process in the glass transition region having an activation energy of 32.8 kcal./mole. The nature of this process and its occurrence in other polymers is discussed. Annealed and unannealed specimens are shown to obey the previously proposed empirical relationship, 1/σ = a + m log t, where σ is the tensile yield strength, t is the time to yield. The values of the constants a and m have been derived.
Torsional braid analysis of antioxidant activity in elastomer systems. I. Initial studies
Authors: Williams Bernard L. , Weissbein Leonard 
Published: April 2003

AbstractThe torsional braid apparatus as originally described by Lewis and Gillham has been explored as a means of providing a quantitative measure of antioxidant activity of selected compounds when formulated with certain elastomer systems prone to oxidative crosslinking on heat aging. With this technique the time dependence of the sharp torsional modulus increase, corresponding to a change from a rubbery to a highly crosslinked state, is determined. This time dependence is taken as a measure of the rate of oxidative crosslinking in heat‐aged elastomer films coated on a fiber‐glass braid. In this manner an assessment of the activity of antioxidants can be made. To illustrate the application of this technique, two initial studies will be cited. In one study the relative protective effect on a carboxylated styrene‐butadiene latex system of a series of antioxidants was found to be in the following order: α, α′‐2,6‐bis(2‐hydroxy‐3‐tert‐butyl‐5‐methylphenyl)xylenol > the reaction product of nonylated paraethylphenol and formaldehyde > crude 2,2′‐methylene bis(6‐nonylparacresol). In another study, with cis‐polybutadiene as the elastomer, the effectiveness of a series of antioxidants was found to be in the following order: 2,2′‐methylene bis(6‐tert‐butyl paracresol) > 1,3,3,5‐tetramethyl‐1‐m‐tolylindane‐4′,6‐diol > 4,4′‐methylene bis(2,6‐di‐tert‐butylphenol). In addition, the effect of concentration and temperature was studied with the most efficient antioxidant in this last series.
Acrylate monomers from olefins via tertiary butyl hypochlorite
Authors: Nevin C. S. 
Published: April 2003

AbstractA variety of olefins were readily converted to acrylate monomers by combining them with t‐butyl hypochlorite and acrylic or methacrylic acid at 25–65°C. The predominate product was the vicinal acyloxychloro derivative formed by addition at the olefinic double bond. By‐products were the vicinal butoxychloro derivative and the still unsaturated chlorinated olefin. The main reaction was shown to occur by an ionic mechanism. 2‐Chloro‐1‐methyl propyl methacrylate was isolated and identified as the main product of the reaction of 2‐butene, methacrylic acid, and t‐butyl hypochlorite. The crude olefin products readily homopolymerized and copolymerized with other vinyl monomers by incorporating free‐radical initiators.
Time‐dependent capillary flow of polyethylene melt
Authors: Kataoka Tadao , Ueda Shigeyuki 
Published: April 2003

AbstractThe variation of output rate with extrusion time is examined experimentally for capillary flow of high density polyethylene melt. The increase in output rate is divided into two parts. One of these is due to the decrease in the amount of the material in the reservoir and is well interpreted from the consideration of the so‐called reservoir effect. The other part is mainly attributed to the disentanglement or orientation of polymer chain during flow in the reservoir.
Diffusion, membrane selectivity, and nonequilibrium effects in rapid membrane osmometry
Authors: Ghosh Kalyan K. , Swenson Harold A. 
Published: April 2003

AbstractRapid membrane osmometry, narrow distribution polystyrenes in the range 4000–700,000, and three membrane types of different porosity were used to study the effects of diffusion and of Staverman membrane selection in osmometry. It was found that equilibrium was not obtained in the rapid measurement with the two densest membranes which led to grossly low values for the high molecular weight sample but had small effect at low molecular weights. Because of membrane selectivity effects at lower, and of nonequilibrium effects at higher molecular weights, the effective range was about 4000–350,000 for the densest membrane, 90,000–500,000 for the medium porosity membrane and from 145,000 to an unrestricted upper limit for the grossest membrane. A unique characteristic of the Mechrolab 501 instrument used in the study is the small constant volume on the solvent side of the membrane which allows determination of the osmotic pressure of the diffused material and its concentration when the molecular weight is known. Diffusion can be avoided if the pressure reading is taken quickly enough but membrane selectivity effects cannot be avoided if diffusible solute is present. Enormous selectivity effects were found when mixtures of diffusible and nondiffusible molecules were measured. Experimental values of the selectivity coefficient Sn of the mixtures were found to agree closely with those calculated from the Staverman equations. Estimates of the coil size of the polymers are given to provide an estimate of the effective porosities of the membranes.
Ultraviolet irradiation of poly(vinyl chlorides). Part I. Effect of substituents on radiation parameters
Authors: Kwei Kwri‐Ping Shen 
Published: April 2003

AbstractThe crosslinking and main‐chain scission of PVC and its derivatives by ultraviolet radiation at 2537 A. were investigated. Examination of the relationship between gel fraction and radiation dose showed that the number of crosslinks formed in pure PVC per 100 e.v., Gc., was 0.29 and did not vary greatly from pure PVC to commercial PVC. However, the efficiency of scission was lowest (Gs = 0.06) for purified PVC, increased to 0.23–0.26 for commercial PVC, and increased further when chelates were substituted on PVC at C1 atoms. Gs for PVC with opper thalocyanine was 0.62, with copper salicylate was 1.38, and was 6.20 with ferrocene. Gc values also increased in the same order, from 0.40 to 3.10. The ratio of main‐chain fractures to number of crosslinks formed (β/α) increased again in this order from 0.1 for purified PVC to 1.0 for PVC–ferrocene. For purified PVC, β/α increased after 36 hr. of ultraviolet irradiations. In the presence of copper salicylate and ferrocene, ion‐radical reactions probably contribute towards the high β/α ratio. Ability of the aromatic substituents to enter chain–transfer reactions with polymeric radicals followed by coupling reactions may contribute partly towards crosslinking in PVC.
Irradiation of poly(vinyl chlorides). Part II. Effect of dynamic mechanical properties
Authors: Kwei K.‐P. S. , Kwei T. K. 
Published: April 2003

AbstractThe dynamic Young moduli of purified PVC and PVC derivatives were measured at room temperature during the course of irradiation by ultraviolet light at 2537 A. wave‐length. The PVC derivatives with copper salicylate, ferrocene, or copper phthalocyanine were prepared by Friedel‐Crafts reaction as described in the previous paper. The loss tangent decreased monotonically with irradiation time, while the dynamic modulus appeared to pass through a maximum. More pronounced variations in both E and tan 6 were observed for the PVC derivatives than for the purified PVC, owing to enhanced crosslinking and scission in the presence of the substituents. The gel permeation chromatograms of irradiated PVC samples have been observed to skew to the left, where low molecular weight material occurs. The decrease in E after long exposure was discussed in terms of molecular polydispersity of the soluble fractions of PVC.
Dye‐sensitized photopolymerizations of acrylic monomers in the presence of fibrous proteins
Authors: Needles H. L. 
Published: April 2003

AbstractDye‐sensitized photopolymerizations of low concentrations (1–5%) of acrylic monomers proceed at 40°C., if fibrous proteins (keratin, fibroin or collagen) are suspended in solution. In the absence of dye (riboflavin or fluorescein) or fibrous protein no appreciable photopolymerization of monomer is observed at the short irradiation times (120 min.). Graft products containing 0.5–23% polymer are found. The quantity of grafted polymer introduced into the protein depends on the chemical nature and concentration of monomer, dye, and fibrous protein. Homopolymerization of monomer is observed to some extent in each graft polymerization. In the presence of oxygen an induction period ia found, but removal of oxygen from solution greatly retards these photo‐polymerizations. Chemical and physical characterization of the protein–polymer products suggests that only a small number of initiation and grafting sites are present in the protein and that the grafted polymer partially resides within the protein matrix. We believe these photopolymerizations proceed via a free‐radical pathway involving radicalabstraction of hydrogen from the protein by dye intermediates.
Instability and failure phenomena in polymer processing with application to elastomer mill behavior
Authors: White James L. , Tokita Noboru 
Published: April 2003

AbstractThe mill behavior of different elastomers is discussed in some detail and contrasted with melt fracture in extrusion. The mill characteristics of elastomers are discussed, with special emphasis on effect of roll speeds and nip and on molecular structure of elastomer. Theories of failure mechanics in polymer processing are contrasted, and a theory of a viscoelastic material that exhibits rupture above a critical recoverable energy is analyzed. Mixing with carbon black is briefly discussed.
The thermal degradation of an amine‐cured epoxide resin at temperatures between 200°C. and 310°C.
Authors: Patterson‐Jones J. C. , Smith D. A. 
Published: April 2003

AbstractThis paper describes the nonoxidative thermal degradation of an epoxide resin based on the diglycidyl ether of bisphenol A crosslinked with p,p′‐diaminodiphenyl methane. Temperatures of degradation lay between 200 and 310°C. and the process was followed concurrently by three means: changes in dielectric properties, changes in infrared spectra, and weight loss. Dielectric properties support the contention that there is a dehydration step during degradation. It is proposed that vacuum curing at high temperature can produce optimum crosslinking. Evidence of phenol and N‐methyl aniline as degradation products is advanced, and possible degradation mechanisms are discussed.
Cerium‐initiated grafting of acrylonitrile onto cellulosic materials
Authors: Hebeish A. , Mehta P. C. 
Published: April 2003

AbstractGrafting of acrylonitrile onto native cotton, swollen cotton, viscose, ramie, and hydrocellulose was studied with tetravalent cerium as initiator. The effect of temperature on the graft yields is examined. With ceric ammonium nitrate the grafting yields are found to be higher at 20 and 40 than at 60°C. Ceric ammonium sulfate, on the other hand, produces more grafting at 60 than at 20 and 40°C. The consumption of ceric ions is less, whereas the per cent graft yields are higher for the swollen cottons and viscose than for native cotton. Graft yields are shown to be related to substrate accessibility if the grafting reaction is carried out under conditions that suppress homopolymerization. Oxidation of these celluloses with CeIV has also been studied. It is found that more CeIV is consumed during grafting than during oxidation of cellulose under identical reaction conditions. Excess CeIV consumed in the grafting reaction has been shown to be directly related to extent of homopolymerization, which accompanies grafting. Some data on the storage stability of the free‐radical activity produced by oxidation of cellulose with CeIV are also reported. It is observed that the cerium‐oxidized samples can initiate graft poly merization even after 4–5 hr. if stored in nitrogen.