bluuebunny/crossref_metadata_2025 huggingface dataset:
Autoxidation of poly(alkylene glycols) in solution
Authors: Reich Leo , Stivala S. S.
Published: April 2003

Data reported for the autoxidation of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) in solution at relatively long reaction times were analyzed. A relatively simple and a more general kinetic scheme with corresponding rate expressions were used. It was found that the more general scheme gave somewhat more satisfactory agreement between calculated and observed values of several reaction variables. Limitations in the applications of both schemes to PEG and PPG autoxidations are mentioned.
Investigation of creep phenomena in polyethylene and polypropylene
Authors: Sinclair James E. , Edgemond John W.
Published: April 2003

Although creep in thermoplastics, especially for polyethylene, has been investigated throughly, not too much information exists to establish activation energies at different stress levels by the application of high stress‐level, short‐time creep tests. Extrapolation of data to zero stress gives a true material activation energy which is a measure of internal resistance to deformation. Descriptions of specific creep parameters and equipment with a relatively simple phototube recording device are offered along with a discussion of results and recommendations for future fields of investigation.
Effect of conjugated trienes on the oxidation of polyisoprenes
Authors: Campbell D. S.
Published: April 2003

The effect of low concentrations of conjugated triene on the rate of oxidation of polyisoprenes has been investigated. At concentrations similar to those expected to occur in sulfur vulcanizates of NR, conjugated trienes exert a significant accelerative effect on both the uninhibited and the inhibited oxidations of squalene. This accelerative effect is also present, but to a lesser extent, in the inhibited oxidation of carbon–carbon cross‐linked NR vulcanizates.
Aging and loss of flocculation activity of aqueous polyacrylamide solutions
Authors: Shyluk W. P. , Stow F. S.
Published: April 2003

There is a rapid and a slow stage in the decrease of reduced specific viscosity versus time (aging) for a solution of a high intrinsic viscosity polyacrylamide in water. The rapid stage is irreversible and has a fairly high temperature coefficient. Results of the latter type are usually associated with a weak‐link scission mechanism, but they can also be reconciled with a disaggregation mechanism. A disaggregation mechanism is also indicated for the rapid stage by an increase in the first‐order rate contant with a decrease in the polymer concentration or an increase in the shear rate and by the absence of the rapid stage during the aging of the same sample in formamide. Chemical changes in the polymer are suspected as being responsible for the RSV change during the slow stage in the aging of the high intrinsic viscosity polyacrylamide and also in the aging of a polyacrylamide of low intrinsic viscosity. The aging of the polyacrylamide of high intrinsic viscosity is paralleled by a decrease in the ability of the polymer to increase the subsidence of kaolin suspensions. This decrease in the flocculation activity is attributed to a weakening of the interparticle bridging by a change from a strong adsorption of the bridging polymer to two particles to a strong adsorption of the bridging polymer to one particle but weak adsorption of the bridging polymer to the other particle.
Reactivity of cotton after treatment in alkaline and acid swelling agents
Authors: Warwicker J. O. , Clayton J. W.
Published: April 2003

The reactivity of scoured Acala 4‐42 cotton before and after treatment with alkaline and acid swelling agents has been assessed by a number of methods. It is shown that the reactivity depends more on the type of swelling, whether it is interfibrillar or intrafibrillar, than on the degree of swelling achieved. Furthermore, the reactivity of the treated cotton depends on whether the reaction is carried out in a nonswelling or a swelling medium. Thus high intrafibrillar swelling can lead to a loss in reactivity of the treated cotton if the subsequent reaction takes place in a medium incapable of swelling the treated cotton, on the other hand, interfibrillar swelling can lead to an increase in reactivity in the same reaction mixture.
Influence of water on stress corrosion cracking of epoxy bonds
Authors: Mostovoy Sheldon , Ripling E. J.
Published: April 2003

Environment assisted fracturing, or stress corrosion cracking of adhesive joints in liquid water or a humid atmosphere was shown to occur at values of applied crack extension force ςa considerably below those required for onset of opening‐mode rapid fracture ςc. The minimum value of ςa below which no cracking was observed, ςSSC, was dependent on the relative humidity and the particular adhesive used. For two adhesive systems, the one with the lower hardener content and post cure temperature showed both a lower absolute value of ςSSC and a lower ratio of ςSSC to ςc. The value of ςSSC for both adhesive systems decreased as the humidity was increased. As the relative humidity approached 100%, the value of ςSSC approached its value for liquid water. Values of ςc for the two adhesives differed by a ratio of approximately 2:1. When water was introduced to the crack tip, ςc for the less tough material increased while it was not significantly changed for the tougher material.
NMR analysis of chlorinated poly(vinyl chloride)
Authors: Svegliado G. , Grandi F. Zilio
Published: April 2003

The chlorination of poly(vinyl chloride) takes place preferentially at the methylenic carbon, leading to 1,2‐dichloroethylenic units, and to a lower extent at the methynic, leading to 1,1‐dichloroethylenic units. The ratio between 1,2‐ and 1,1‐dichloroethylenic units tends to decrease with increasing degree of chlorination, and it seems to depend also on the chlorination conditions. The number‐average sequence length of 1,2‐dichloroethylenic units does not differ significantly from 1 during a great part of the process, substantially in agreement with a random distribution of these units along the chain. The 1,1‐dichloroethylenic units can be found either between two unchlorinated units or at one end of a sequence of chlorinated units. Since among the unchlorinated units more racemic units are present than expected for a completely random chlorination, it can be suggested either that chlorination is affected by stereoregularity or that it does not take place in the crystalline regions of the polymer.
Radiation‐induced emulsion polymerization of vinyl acetate and styrene
Authors: Stannett V. , Gervasi J. A. , Kearney J. J. , Araki K.
Published: April 2003

Studies have been made of the γ‐induced emulsion polymerization of styrene and comparisons made with chemically initiated emulsion polymerization. The polymerization proceeded smoothly to high conversions at 0 and 60°C, the reaction showing a high G (monomer) value. Complete conversions were obtained with total doses of less than 0.05 Mrad. In accordance with the behavior expected of systems having a constant rate of initiation, the molecular weight was found to decrease with decreasing temperature. The molecular weight and particle size distributions were narrower than those obtained in chemically initiated emulsion polymerizations at the same temperature. The radiation‐induced emulsion polymerization of vinyl acetate proceeded smoothly at temperatures in the range 0–50°C to give polymers of much higher molecular weight than these obtained from chemically initiated polymerizations at the same temperature. Complete conversion was attained after a dose of 0.02 Mrad for latices approaching 50% solids. The elimination of ionic endgroups in the poly(vinyl acetate) radicals tends to drive the polymerization from the aqueous phase, resulting in faster rates and higher molecular weights than are obtained from chemically initiated systems. Rates of polymerization were found to be independent of temperature and the molecular weight of the polymer to be independent of dose rate. Latices of poly(vinyl acetate) of high solids content were evaluated for latex and film properties and found to have improvements over commercially available samples in both areas, especially in clarity of film and scrub resistance. A number of acrylate and maleate esters were copolymerized with vinyl acetate in a radiation‐initiated emulsion system. High molecular weight copolymers were produced after low dose.
Structural characterization of vulcanizates part X. Thiol‐disulfide interchange for cleaving disulfide crosslinks in natural rubber vulcanizates
Authors: Campbell D. S.
Published: April 2003

The thiol‐disulfide exchange reaction is shown to be applicable to cleavage of disulfide crosslinks in accelerated sulfur vulcanizates of natural rubber. The reaction, in conjunction with the previously reported selective cleavage of polysulfide crosslinks, is used to determine the distribution of crosslink types for several accelerated sulfur vulcanization systems as a function of cure time. Discrepancies between the results and published results obtained using the reagent sodium di‐n‐butyl phosphite for disulfide crosslink cleavage are discussed.
The cupric sulfate‐hydrazine‐oxygen system as an initiator for the emulsion polymerization of methyl methacrylate
Authors: Bond Joan , Lee P. I.
Published: April 2003

The kinetics of the emulsion polymerization of methyl methacrylate initiated by the cupric sulfate‐hydrazine system in the presence of oxygen have been evaluated.

A maximum rate of polymerization occurs at a cupric sulfate concentration of 1.8 × 10−4 mole liter−1. The adsorption of cupric ion on the micelles and the adsorption of soap on cupric hydroxide are discussed as an explanation of this effect.

A reaction between hydrazine and methyl methacrylate produces a surface active agent which enhances the rate of polymerization and increases the number of particles at high ratios of monomer concentration to soap concentration.

The kinetics follow the mechanism of Gershberg rather than that of Smith and Ewart, and the initiation of the emulsion polymerization appears to take place inside the micelle rather than in the aqueous phase as was proposed by van der Hoff for styrene.

The activation energy for the complete process is 23.7 kcal mole−1.
The mechanical properties of films and their relation to paint chipping
Authors: Bender Howard S.
Published: April 2003

A correlation has been made between dynamic mechanical properties and impact resistance of a multicoat paint system. It has been determined that the shear or rigidity modulus and damping of free primer films are some of the parameters that control the impact characteristics of the system. Those films of low modulus and high damping show the best chip resistance. A series of physical and chemical modifications were made on the primer and chipping results were compared with dynamic mechanical properties of free paint films. It was found that increasing cure temperature, addition of catalysts, decreasing the oil length of the resin, increasing the amount of pigmentation and increasing the tension and strain rate all led to increased paint chipping and increases in the modulus of rigidity. Two new primers were synthesized which incorporated the above results and were found to give increased gravel impact resistance.
Thermal conductivity of some electron transfer polymers
Authors: Jenkins Robert K. , Byrd Norman R. , Lister James L.
Published: April 2003

A number of electron transfer polymers were prepared by reacting various α, ω‐alkanediamines with benzoquinone. The resulting polymers, through the formation of inter and intramolecular complexes, displayed high thermal conductivity with a strong temperature dependency. The mechanism contributing to the increased thermal conductivity was attributed to strong interchain complexing.
The thermal analyses of polymers. II. Thermomechanical analyses of segmented polyurethane elastomers
Authors: Miller G. W. , Saunders J. H.
Published: April 2003

The development of new and more sensitive techniques in thermal analyses aids in a more complete understanding of the contributions of individual components in urethane elastomers regarding their mechanical and thermodynamic behavior. The behavior of various segments of the elastomers reported in this work illustrates a clearer interpretation of reasons for changes in mechanical behavior caused by changes in heat capacity, volume and tensile properties; the gross changes previously reported for polyurethane properties as a function of temperature are also confirmed with a more exact definition of their origin.

The sub‐ambient temperature behavior and response of physical measurements near the melting point of the backbone polyol are largely a function of the so‐called “soft block.” The soft block does not contribute to the mechanical properties above the melting point of the polyol unless some urethane segments from the diisocyanate and extender are structured into the soft block, that is, excess diisocyanate and extender are added to build in the “hard” block. The extender and isocyanate influence for both low and high temperature properties is observed by the lack of molecular fit imparted to the backbone polyol as well as some crystallinity in the polymer hard block. The usual Tg transition reported in urethane elastomers corresponds to a first‐order transition in the polyester or polyether backbone.
Kinetics of autoxidation of isotactic polybutene‐1 by infrared spectroscopy
Authors: Stivala S. S. , Yo G. , Reich Leo
Published: April 2003

The autoxidation of a film of isotactic polybutene‐1 (IPB) containing a relatively large amount of metallic ash (≈0.2%) was studied by means of infrared spectroscopy. Reaction temperatures were varied from 105 to 120°C and oxygen concentrations from 25 to 100% by volume. A reaction scheme previously reported for the autoxidation of atactic polybutene‐1 (APB) was utilized for the IPB. Various results obtained for IPB were compared with those previously reported for APB.
Stress softening in elastomer blends
Authors: Meluch William C.
Published: April 2003

Compressive stress softening (Mullins effect) in black‐filled vulcanizates of the blended system natural : nitrile : brominated butyl rubber has been investigated. The results are expressed in terms of parameters derived from successive stress‐strain cycles. The ratio of the work done on loading in the first and second cycles is called the load work ration, Rw. A similar quantity, Rh, is defined for the loss or hysteresis work. Both load and loss work ratios show a compositional dependence similar to other properties of blends. The variation of Rw and Rh with composition agrees with the recent thesis of Mullins, Harwood, Payne and others that the Mullins effect is a property of the elastomer. Sudden variation of Rh with elongation has been interpreted in light of recent results of R. W. Smith as indicative of vacuole formation.
The continuous synthesis of addition polymers with a pricesely controlled average molecular weight and minimum polydispersity
Authors: Kenat Thomas A. , Kermode Richard I. , Rosen Stephen L.
Published: April 2003

A novel technique for the control of continuous synthesis of addition polymers with precisely controlled average molecular weight and minimum polydispersity has been developed. A control system adjusts the concentration of chain‐transfer agent in the reactor feed to compensate for all other upsets, in the reactor inputs: initiator and monomer concentrations, temperature and feed rate. The technique has been evaluated quantitatively on a digital computer using a kinetic model of homogeneous, free‐radical solution polymerization. In computational tests, the modeled control system generally held the instantaneous number‐average chain length within 1%, and quickly returned it to the desired value in response to a wide variety of upsets. By generalizing the Schulz distributions to include termination by disproportionation, combination and chain‐transfer, it is shown that changes in the molecular‐weight distribution resulting from the action of the control system are minor.
Rate effects in the measurement of polymer transitions by differential scanning calorimetry
Authors: Strella S. , Erhardt P. F.
Published: April 2003

Depending on heating rate, differences as large as 15°C in polymer transition temperatures may be observed in DCS measurements. A heat transfer analysis of the method shows that this rate dependence is a result of a lag in the heat path to the test sample and lag in heat transfer within the sample. Experiments confirmed the analysis. Methods for obtaining the correct values of transition temperatures are given.
Polymer reactors and molecular weight distribution. VIII. A method of interpreting skewed GPC chromatograms
Authors: Balke S. T. , Hamielec A. E.
Published: April 2003

A new‐method of interpreting GPC chromatograms which accounts for skewing and symmetrical axial dispersion has been developed. General relationships for a symmetrical axial dispersion correction and for a skewing correction are derived.

The method has been verified experimentally for unimodal chromatograms and linear calibration curves over a wide range of GPC operating conditions, polymer molecular weights and polydispersities. Measurements of h and skewing factors were obtained by a once‐through technique. The need for performing reverse flow experiments has been eliminated. Artificial oscillations in the corrected chromatogram due to step size (Method of Pierce‐Armonas), and to number of terms in a polynomial expansion (Method of Tung and Method of Smith) are eliminated.

The method has yet to be evaluated for nonlinear calibration curves and multi‐modal distributions. However, suggestions for its application in these circumstances are presented.
Multiaxial impact measurements of polypropylenes
Authors: Fujioka Kazuyoshi
Published: April 2003

A new puncture tester of the falling weight type for conducting impact tests has been developed. With this tester, impact energy can be measured by means of an accelerometer fixed in the falling weight, and strength by a compression type load cell placed under a pot clamping a sample. Puncture behaviors are traced on an oscilloscope.

Results of puncture measurements of isotactic propylene homopolymers and copolymers with ethylene showd that impact behaviour depended noticeably upon temperature. Ethylene concentration, isotacticity and molecular weight of polypropylene resins were not more effective in sustaining impact resistance in the range of temperatures below the brittle point than in bringing down the brittle point itself. It was confirmed by means of tensile impact tests that energy to failure depended not upon yield strength but upon deformation in ductile rupture, whereas in the brittle rupture case energy to failure depended primarily on the strength of the material.

Dynamic mechanical measurement was also carried out to secure the relationship between crystallinity and impact resistance.
The photo‐oxidation of polypropylene: Some effects of molecular order
Authors: Kato Y. , Carlsson D. J. , Wiles D. M.
Published: April 2003

Fractional crystallization was used to separate a commercial, predominatly isotactice, unstabilized polypropylene into fractions of relatively low and relatively high atacticity, but of similar molecular weight. IR spectroscopy was used to follow the photo‐oxidations of films formed from these fractions during irradiation in air with light of wavelengths greater than 3000 À. The major oxidation products included hydrogenbond hydroperoxides and carbonyl compounds. Films of constant tacticity, but varying morphology were prepared by quenching from the melt. No distinct correlation was found between sample photostability and morphology, as indicated by film density. Films of low atactic content were found to undergo faster photo‐oxidation than films of high atactic content, irradiated under identical conditions. This effect is believed to be due to the occurrence of a stereo‐dependent step (or steps) in the oxidative chain, and not due to differences in sample morphology. The possible nature of the stereo‐dependent steps is considered in terms of well‐established oxidative chain processes. The effects of polypropylene polymorphism on oxygen permeability are briefly considered.
Grafting of preformed polyethylene oxide on starch
Authors: Ezra Gabriel , Zilkha Albert
Published: April 2003

Polymer‐polymer interaction was used for the preparation of graft polymers of polyethylene oxide on starch. Preformed polyethylene oxide having hydroxyl end groups was converted to the chloroformate derivative and reacted with starch alkoxide. Watersoluble graft polymers were obtained free of cross linking. The efficiency of the coupling process decreased with increasing the DPn of the polyethylene oxide.
Effect of crystalline structure on the trapped radical spectra of irradiated cellulose
Authors: Arthur Jett C. , Hinojosa Oscar , Tripp Verne W.
Published: April 2003

The effects of crystalline modification of cellulose and of water on the ESR spectra generated by the trapped free radicals in gamma‐irradiated celluloses were investigated for cotton cellulose I, II, III, and IV, partially decrystallized cotton cellulose, ballmilled cotton cellulose, hydrocelluloses of cellulose III and IV, and ramie. On irradiation of the celluloses, free radicals were formed on the cellulose molecule, probably following dehydrogenation or chain cleavage. The free radicals located within the less ordered or amorphous regions of the cellulose reacted readily with water and were terminated. The radicals located within the more ordered regions of the celluloses could be made accessible to reaction with water by the interaction of the celluloses with solvents which caused dimensional changes in the cellulosic structure. In the highly ordered regions of the celluloses, even after long periods of time in solvents which caused large dimensional changes in the cellulosic structure, the trapped free radicals were not terminated by reaction with solvent or water. The ESR spectra of the irradiated, dried celluloses were determined at −160°C, the single‐line spectra recorded had line widths of about 18‐24 gauss. On the absorption of water by the irradiated celluloses, the ESR spectra changed and were dependent on the crystalline structure of the irradiated celluloses. The effects of different arrangements of the irradiated celluloses, as shown by their trapped radical spectra, particularly after interaction with water, were discussed.
Difluorocarbene modification of polymer and fiber surfaces
Authors: Olsen Douglas A. , Osteraas A. Jean
Published: April 2003

Difluorocarbene (difluoromethylene, :CF2) generated by the pyrolysis of sodium chlorodifluoroacetate has been shown to irreversibly modify the surfaces of polymers and fibers. The critical surface tension values of several polymers are shown to decrease with increasing exposure to difluorocarbene vapors and ultimately approach the critical surface tension values of partially fluorinated polyethylenes. The rate‐controlling step appears to be the diffusion of difluorocarbene from the precursor to the polymer substrate. The nature of the interaction between difluorocarbene and the polymer surface is unknown; however, the absence of infrared bands due to CF bonds in attenuated total reflection measurements tends to establish the mono‐molecular‐like character of the modified surface.
Studies on disulfide‐crosslinked nylon. I. Elastic disulfide‐crosslinked polycaprolactam fiber
Authors: Tonami Hiroaki , Miyauchi Shin'nosuke , Sakamoto Munenori
Published: April 2003

Elastic disulfide‐crosslinked polycaprolactams of different sulfur contents (0.4‐3.3%) were prepared by the reaction of N‐methoxymethyl polycaprolactam (D.S., 0.30) with different amounts of thiourea, the hydrolysis with excess potassium hydroxide, and the spinning into aqueous hydrogen peroxide.

The fibers obtained exhibited high elongation at break (500‐300%), low initial modulus (13‐1 kg/mm2), and high elastic recovery. The initial modulus decreased with increased crosslinking. Heat‐treatment of the fibers at 140°C lowered the initial modulus remarkably. The effect of the crosslinking and the residual methoxymethyl substitution on the structure and the physical properties of the untreated and heat‐treated fibers is discussed.

The residual methoxymethyl groups were removed completely from the fibers by hydrolysis with formic acid. The removal led to marked reduction in the elongation and much increase in the initial modulus.
Environmental stress relaxation studies of polymers: Effect of benzene series hydrocarbons on polyethylene
Authors: Nisizawa Mizuho
Published: April 2003

The method of stress relaxation has been used to study stress decay behavior in the system of polyethylene—benzene series hydrocarbons. The behavior of stress decay in polyethylene under benzene series hydrocarbons was observed and the respective activity forward stress decay of benzene series hydrocarbons was obtained.
The reaction of polypropylene with maleic anhydride
Authors: Minoura Yuji , Ueda Minoru , Mizunuma Susumu , Oba Mareo
Published: April 2003

An addition reaction of maleic anhydride with polypropylene takes place in the presence of radical reagents or sunlight. The initial rate of the reaction was proportional to the concentration of polypropylene and maleic anhydride, and one‐half power of the concentration of the radical reagents. The increase in the temperature from 80 to 120°C increased the rate of the reaction and di‐cumyl peroxide was effective as a radical reagent for this reaction.

Ionic crosslinked rubber‐like polymers were obtained from the reaction of maleic polypropylene with some alkali metal compounds. They showed the characteristic absorption band due to COO⊖ in their infrared spectra.
Dynamic mechanical properties of polymers
Authors: Legrand D. G. , Erhardt P. F.
Published: April 2003

A technique, employing samples in the form of tuning forks, to measure the mechanical properties of polymers is presented. Results for low density polyethylene, polypropylene, and polycarbonates are shown. A large transition is observed for polypropylene at approximately +10°C and a small transition at −100°C for the polycarbonates. Polycarbonate data has also been obtained from 20 to 150°C, at approximately 70 cps. Effects of time, temperature, and history are presented.
Tetrachlorinated rubber: The addition of carbon tetrachloride to 1,4‐polybutadiene
Authors: Rosin Hadassa , Asscher M.
Published: April 2003

The iron chloride‐catalyzed radical chain addition of carbon tetrachloride to 1,4‐polybutadiene has been studied. Transparent film forming nonflammable polymers are obtained which contain 50–55% chlorine. Cyclization appears to accompany the addition of carbon tetrachloride as an integral part of the radical reaction.
Studies on adhesion of allylic resin. I. Adhesion of diallylphthalate resin and dichromate‐treated copper foil
Authors: Nara Shigeo , Matsuyama Kentaro
Published: April 2003

An effective copper surface treatment for adhesive bonding of copper foil and diallylphthalate resin was investigated.

It involves dipping the copper foil in the potassium dichromate‐sulfuric acid solution (K2Cr2O7:76 g/l, H2SO4:0.67 N) at 60°C for 5 min. The dichromate treated copper foil and glass based prepregs of diallylphthalate resin were laminated under the pressure of 38 kg/cm2 for 30 min at 145°C.

Interface characteristics of the dichromate treated copper foil and diallylphthalate resin were examined.

It was found that chromium is formed on the surfaces of the treated copper foil, and allyl groups in diallylphthalate molecule are oriented to the atoms, that is, the adhesive bonding is performed by the chemical affinity of chromium and allyl groups.

The allyl group has a delocalized π‐electron system, and that its bonding to a transition metal as chromium is appropriate and justifiable by quantum chemical considerations.
Ionic graft copolymerization. VIII. Homopolymerization of β‐propiolactone by radical catalysts in the presence of electron acceptors and application to graft copolymerization
Authors: Shiota Tetsuya , Hayashi Koichiro , Okamura Seizo
Published: April 2003

The polymerization of β‐propiolactone (βPL) induced by radiation and by radical catalysts, the influences of radical inhibitors and electron acceptors on this polymerization, and graft copolymerization were studied. It was found that βPL was polymerized by benzoyl peroxide in the presence of electron acceptors such as maleic anhydride and acrylonitrile. This polymerization method was applied to graft copolymerization. The electron donative trunk polymer containing ether groups was heated with benzoyl peroxide or was irradiated by γ‐rays from Co60 in the presence of maleic anhydride as the electron acceptor. βPL was added subsequently to form the graft copolymer.
Properties of PVC. III. Influence of the way of processing on the properties of PVC samples
Authors: Maláč J.
Published: April 2003

The work shows PVC qualitative dependence under the conditions for the preparation of samples and some of their properties. The different ways of preparation influences the differences of residual stress and the free volume of samples, which is apparent even on properties, the measuring of which is not sufficiently precise, and therefore the differentiating ability is small (as, e.g., the notch impact strength).
Mechanical properties and transition temperatures of copolymers of N‐n‐alkylacrylamides and vinylidene chloride
Authors: Jordan Edmund F. , Riser George R. , Artymyshyn Bohdan , Parker Winfred E. , Pensabene John W. , Wrigley A. N.
Published: April 2003

Mechanical and solution properties, melting transitions, torsional stiffness temperatures, Tf, and selected modulus‐temperature curves are presented for copolymers of the N‐n‐alkylacrylamides with vinylidene chloride. Copolymers were prepared at 60°C across the range of compositions, using as comonomers N‐n‐butyl‐, octyl‐, dodecyl‐ and oleyl‐acrylamide, which have amorphous side‐chains, and N‐n‐octadecyl acrylamide and n‐octadecyl acrylate whose side‐chains are crystalline. The mechanical properties reflected the effect of the decline in backbone crystallinity and the simultaneous development of strong intermolecular interactions in the amorphous stage. Copolymers were stiff or showed brittle failure across the compositional range except when intermolecular forces were reduced (with n‐octadrcyl acrylate) and side‐chain crystallization eliminated (with N‐oleylacrylamide). These systems and the n‐dodecylacrylamide copolymers had yield strengths less than brittle strengths and substantial elongations. Backbone crystallinity was eliminated at about 15 mole % amide and side‐chain crystallinity vanished at less than 10 mole % of the amide in the N‐n‐octadecylacrylamide series. No depression in side‐chain melting point occurred with dilution by segments of vinylidene chloride. Over‐all decline in the flex‐temperature was the normal monotonic function of composition except that values increased in magnitude at high vinylidene chloride contents, the effect presumably being caused by the presence of crystallinity. An empirical equation was developed which permitted the calculation of Tf for any N‐n‐alkylacrylamide composition with any number of carbon atoms in the side‐chain, above 3.
Radiation‐induced copolymerization of maleimides and acenaphthylene in the solid state
Authors: Yamakita Hiromi , Hayakawa Kiyoshi
Published: April 2003

The γ‐ray‐induced polymerizations in the binary systems of maleimide‐acenaphthylene and N‐methylmaleimide‐acenaphthylene have been studied. The phase diagrams of the two systems show that an eutectic was formed in each system. It has been proven by the solvent extraction and the turbidimetric titration of obtained polymer that copolymer was formed in the eutectic of each system together with homopolymers. The fraction of total homopolymers in the maleimide‐acenaphthylene system was nearly the smallest in the monomer mixture of the eutectic composition. The composition of the copolymer, which was isolated by the extractions, was almost independent of the monomer composition. In order to elucidate these results, it was postulated that the copolymerization occurred at grain boundaries between the two components in the eutectic.
Reversible crosslinking in cellulose. I. Determination of mercaptan and disulfide in modified cotton
Authors: Sakamoto Munenori , Yamada Yoshio , Tonami Hiroaki
Published: April 2003

Mercaptan and disulfide contents of modified cotton fabrics could be determined by application of Leach's polarographic method for wool, with minor modification.

It was found that mercaptocellulose prepared by the reaction of tosyl cellulose and potassium thiolacetate followed by alkaline hydrolysis contained considerable amounts of disulfided in addition to mercaptain. Iodometric titration of mercaptocellulose gave a higher value of mercaptan than that obtained by the polarographic method. The mercaptan and disulfide contents and methylene blue uptake of the iodine‐treated samples indicate that some of the mercaptan groups further undergo oxidation to acidic groups as a result of the iodine treatment.

The spatial effect in the oxidation of mercapto groups in modified cotton is briefly discussed.
Effect of titanium compounds on thermooxidative properties of stabilized polypropylene
Authors: Kresta Jiří , Majer Josef
Published: April 2003

The effect of titanium compounds on thermooxidation stability of stabilized polypropylene was studied. It was found that the presence of titanium compounds shortens the induction period of PP oxidation. This phenomenon is brought about by the thermal reactions of titanium compounds with antioxidants which take place during polymer processing. The first step is the reaction of TiCl with OH groups of phenolic antioxidant, which gives rise to a colored titanate and HCl. Hydrogen chloride functions as a Friedel‐Crafts catalyst for degradation and dealkylation of phenolic antioxidants. The products of degradation have a very low stabilization efficiency. Hydrogen chloride acceptors suppress antioxidant degradation and increase the polymer stability even in the presence of small amounts of titanium compounds.
Structure‐property relationships in elastomer‐modified terpolymer systems
Authors: Hagerman Edward M.
Published: April 2003

A number of terpolymers, incorporating as the elastomer phase polybutadiene, polyisoprene, poly‐2,3‐dimethylbutadiene, poly(butadiene‐co‐styrene), and poly(butadiene‐co‐2‐methyl‐5‐vinypyridine), were studied. Matrices were composed of poly(styrene‐co‐acrylonitrile) (SAN), poly(α‐methylstyrene‐co‐acrylonitrile), and poly(styrene‐co‐acenaphthylene). At constant elastomer content and elastomer molecular weight in systems employing a SAN matrix, Izod impact resistance was found to vary inversely with rising elastomer‐glass transition temperature. In systems of various matrix composition, using a polybutadiene elastomer, heat deflection temperatures were found to very directly and impact resistance inversely with rising matrix‐glass transition temperature. In acrylonitrile–butadiene–styrene (ABS), systems of constant matrix composition and elastomer content, varying the elastomer molecular weight from 0.6 to 2.6 × 105 resulted in increasing the Izod impact resistance from 0.67 to 12.8 ft‐lb/in. of notch.
Redox behavior in photochromic polymers of the thiazine series
Authors: Kamogawa Hiroyoshi
Published: April 2003

The photochromic redox behavior of the thiazine polymers prepared by the condensation reactions of the N‐hydroxymethylacrylamido components of vinyl polymers with four thiazine compounds, i.e., thionine and asym‐dimethyl‐, trimethyl‐, and mono‐methylthionine chloride, in combination with various electron‐donating components, including hydroxyl, amino, and sulfhydryl groups and ferrous ion, were investigated.

The reversible color fading (at ca. 600 mμ) of the thiazine polymers under illumination in the solid state was found to be largely dependent upon the moisture content in the polymer. This, together with other evidence, suggests that water molecules adsorbed on the active groups in the polymer also participate in the reduction of the thiazine components. Polyvinyl alcohol, cellulose, and enzymes such as papain, when incorporated in the photochromic compositions, induce remarkable improvements of the photochromism, in both the sensitivity to light and the rate of color recovery in dark; the incorporation of the ferrous–ferric ion system into the polymers in the form of acrylates also improves photochromism remarkably, especially the rate of recovery.
Durability of bimetallic‐adhesive laminate with ethylene–acid copolymer adhesives
Authors: Wargotz B.
Published: April 2003

A broadband multicoaxial cable has been developed, based upon the use of ethylene copolymer thermoplastic adhesives to bond tin‐plated steel to copper. The characteristics of the adhesive and the integrity of the bond formed between the dissimilar metals were of prime interest. The copolymers of ethylene examined as adhesives were ethylene–acrylic acid (EAA) and ethylene–methacrylic acid (EMAA). The influence of high humidity on the durability of bimetallic laminates of copper or aluminum with tin‐plated steel and ethylene–acid copolymer adhesives has been studied. Infrared spectrometric and differential thermal analysis data had shown that a contributing cause to failure of bonds between EAA copolymers and copper is the solubilization of an underlying weak copper oxide layer under condition of the test. Electrolytic chromate‐treated copper and immersion chromate‐treated aluminum bonded to degreased tin‐plated steel resulted in joints having comparable durability under stress and humid environments. These results reflect the durability of tin–tin bonded specimens. These materials engineering studies have shown that ethylene–acid copolymer adhesive, properly used and stabilized, can be employed with confidence in adhesive joints.
Studies on the mechanism of fine‐structure development during industrial cellulose yarn production
Authors: Bromley K. , Aitken R.
Published: April 2003

A study has been made of the diffusion of zinc ions into alkaline solutions of sodium cellulose xanthate (viscose) when these are extruded into acidified salt solutions (spin‐bath). Under these conditions, which exist during the manufacture of regenerated cellulose industrial yarns, the zinc ions are diffusing into a continuously coagulating gel structure from which water is exuded as the structure is developed. It has been shown that the presence of certain additives (modifiers) in the viscose can slow down the diffusion of both zinc and hydrogen ions, thus retarding the coagulation and neutralization of the viscose. In the initial stages of coagulation, before the neutralization point is reached, the modifiers reduce the rapid filament shrinkage and pressure rise within the filament which would otherwise be caused by the presence of zinc ions in the spinbath. The mode of action of the modifiers is discussed in the light of current theories. A hypothesis is put forward that the modifiers act by preventing the initial rapid shrinking action of the outer cuticle of the filament. This permits the production of the desired fine structure inside the filament during a slower steady shrinkage which leads to a round cross‐sectioned filament of good mechanical properties.
Base‐hydrolyzed starch‐polyacrylonitrile (S‐PAN) graft copolymer. S‐PAN‐1:1, PAN M.W. 794,000
Authors: Gugliemelli L. A. , Weaver M. O. , Russell C. R. , Rist C. E.
Published: April 2003

Starch‐polyacrylonitrile (S‐PAN) graft copolymer consisting of one part starch and one part polyacrylonitrile (M. W. 794,000) was hydrolyzed with aqueous KOH at 80 and 100°C to polyelectrolytes containing carboxyl and amide functionality but void of infrared‐detectable amounts of nitrile. Viscosities of potassium salts of the polyelectrolytes in water were pH dependent with peak viscosities at 8.5. These dispersions were characterized by unusually high viscosities, 15,000 to 26,500 cp at 1% concentration, and by the ability to retain significant viscosities, 300 to 950 cp, upon dilution to 0.03% concentrations. A 1% dispersion of hydrolyzed S‐PAN had a viscosity of 5,000 cp in the presence of 8% KCl; however, the depressing effect of added salts on viscosity of aqueous dispersions of hydrolyzed S‐PAN increases as the valence of the cation increases.
Polymerisation du chlorure de vinyle par les systèmes Ti(OR)y Cl4–y–AlRxCl3–x en milieu CCl4
Authors: Guyot A. , Rocaniere P.
Published: April 2003

Vinyl chloride polymerizations by Ti(OR)yCl4–y–AlRxCl3–x systems, using carbon tetrachloride as solvent, obey a radical mechanism. Free radicals are generated from alkyl aluminum by way of decomposition of an organometallic compound of tetravalent titanium; the latter is formed either by direct reaction between aluminum and titanium compounds, or after reoxidation by CCl4 of a compound of trivalent titanium. The organometallic compound so obtained contains organic groups more complex than the alkyl group initially bond to aluminum.
The effect of impulsive preloadings on the behavior of quartz phenolic
Authors: Perkins R. D. , Babcock S. G. , Schierloh F. L. , Jones A. H.
Published: April 2003

Uniaxial strain and uniaxial stress preloadings were performed on quartz phenolic in order to assess the effect of an impulsive preload on the subsequent uniaxial stress behavior of a composite material. In these tests observable damage was limited to the phenolic matrix. As a result, postpreload experiments on the specimen under uniaxial stress correlated the dependence of the fracture strength with the extent of the damage to the phenolic matrix as well as the direction of the reload relative to the fiber layup.
Graft copolymerization of styrene with carbon black‐alkali metal complex
Authors: Minoura Yuji , Katano Masahide
Published: April 2003

It was found that an ion radical complex is formed by the reaction of carbon black with an alkali metal (Li, Na, K) in tetrahydrofuran. The graft copolymerization of styrene with carbon black was carried out using the ion radical complexes as initiator, and free polystyrene and carbon black‐polystyrene graft copolymer were obtained. The identification of the graft copolymer with carbon black was carried out by fractionation and thermal degradation. The initiation activity of the alkali metals increased in the order Li < Na < K. The effect of the particle size of the carbon black on the graft copolymerization was studied.
Apparent anomalous thermal behavior of polymers undergoing a glass transition
Authors: Roberts R. C. , Sherliker F. R.
Published: April 2003

Glass transitions in certain polymer samples were detected as a step change in a DTA trace in the exothermic sense. This anomaly is explained as a manifestation of the volume relaxation shown to occur at the glass transition in internally strained samples.
The pyrolysis of acrylic fiber in inert atmosphere. I. Reactions up to 400°C
Authors: Turner W. N. , Johnson F. C.
Published: April 2003

The pyrolysis of acrylic fiber up to 400°C in an inert atmosphere at 1° and 6°C/min was studied by means of thermogravimetric and differential thermal analysis. The exothermic reaction occuring at 180–300°C was shown to be due to the reaction of nitrile groups by comparing the extent of exotherm with the number of nitrile groups present, determined by infrared spectroscopy. In addition, results of single‐fiber tensile measurements, density, and elemental analysis of the pyrolyzed fibers are interpreted in terms of possible molecular structures. The gases evolved on pyrolysis were analyzed for both ammonia and hydrogen cyanide and the liberation of ammonia was attributed to a termination reaction of the polymerization of nitrile groups. The critical conditions necessary for the production of high strength and modulus carbon fiber are discussed briefly in ralation to the chemical changes occurring on pyrolysis.
Activated gas plasma surface treatment of polymers for adhesive bonding
Authors: Hall J. Richard , Westerdahl Carolyn A. L. , Devine Andrew T. , Bodnar Michael J.
Published: April 2003

Polyethylene, polypropylene, poly(vinyl fluoride) (Tedlar), polystyrene, nylon 6, poly(ethylene terephthalate) (Mylar), polycarbonate, cellulose acetate butyrate, and a poly(oxymethylene) copolymer were treated with activated helium and with activated oxygen. Mechanical strengths of adhesive‐bonded specimens prepared from treated and from untreated coupons were compared. Polyethylene (PE) and polypropylene (PP) showed the greatest increases in bond strength. Oxygen and helium were both effective with polyethylene, but polypropylene showed no improvement when treated with activated helium. The results with excited helium parallel the effects of ionizing radiation on these two polymers, as does the appearance of unsaturation bands in the infrared (965 cm−1in PE, and 887 and 910 cm−1in PP). Active nitrogen produced excellent bond strength with polyethylene but not with polypropylene. Of the remaining polymers examined, Tedlar, polystyrene, and nylon 6 showed the greatest improvement in bondability after treatment, and Mylar showed moderate improvement. Polycarbonate, cellulose acetate butyrate, and the poly(oxymethylene) copolymer gave approximately two‐fold increases in lap‐shear bond strength. In several cases, significant differences in response to time of treatment and type of excited gas were found.
Supercooling of polydimethylsiloxane
Authors: Helmer J. D. , Polmanteer K. E.
Published: April 2003

This study was undertaken to determine the quenching rates necessary to supercool polydimethylsiloxane. A technique was developed that allowed controlled quenching rates up to 52°C/see and a modified DTA apparatus was used to obtain thermograms during the warm‐up cycle. No supercooling was observed for a cooling rate of 1.6°C/sec; 56% supercooling was found for a 9.6°C/sec cooling rate; 65% for 10.6°C/sec and 85% for a 52°C/sec cooling rate. Evidence was also presented showing that the crystals in polydimethylsiloxane consist of two forms.
Dielectric relaxation and crosslinking in unsaturated polyester resins
Authors: Learmonth George S. , Pritchard Geoffrey
Published: April 2003

The properties of crosslinked thermosetting resins depend markedly on the completeness of the crosslinking process. Determination of the degree of cure of an unsaturated polyester resin has been studied previously by mechanical, spectroscopic and volume resistivity methods. In this respect the effect of cure time and temperature on the ac dielectric constant and dissipation factor at 1 kc/s and 10 kc/s is considered. The dissipation factor appears to be a most useful parameter for detecting changes in the degree of cure in the later stages of reaction.

The electrical properties of the cured resin are discussed, and values for the energy of activation for electrical conduction are compared with literature reports on similar materials.