bluuebunny/crossref_metadata_2025 huggingface dataset:
Pyrolysis of poly(methyl methacrylate co ethyl acrylate)
Authors: Ferlauto E. C. , Lindemann M. K. , Lucchesi C. A. , Gaskill D. R.
Published: April 2003

An investigation of the behavior of poly(methyl methacrylate co ethyl acrylate) with a commercially available filament‐type pyrolysis unit and gas chromatogaph was conducted. It has been hypothesized that the quantity of ethyl acrylate monomer produced under the conditions of the experiment is dependent upon the number of ethyl acrylate–methyl methacrylate bonds contained in the copolymer. These observations were made possible by a standardized samples‐handling technique in which a uniformsize disk was pyrolyzed at a maximum pyrolysis temperature of 600°C. This enabled reproducible pyrolysis gas chromatograms to be obtained and permitted pyrolysis products of copolymers containing different ratios of ethyl acrylate and methyl methacrylate to be compared. An examination of sequence distribution data, obtained with the aid of a sequence distribution program for copolymers, showed sufficient agreement with the pyrolysis data to support the hypothesis. It has been demonstrated that pyrolysis gas chromatography may be applied to experimentally determine the sequence distribution of copolymers.
Calculation of stress–strain curves from relaxation data in the rubbery flow region
Authors: Narkis M.
Published: April 2003

Stress relaxation curves for polysulfone and Lexan polycarbonate are only time dependent at a constant temperature if strain is defined as ϵH = In (l/l0) and the “true” cross‐sectional area A = A0/(1 + ϵ) is used. The strain‐independent stress relaxation curves can be used to calculate stress–strain curves at different rates of strain according to the linear viscoelastic theory. The agreement between experimental and calculated stress–strain curves is good at least up to about 60% strain in the range of 0.01 to 0.2 in./min rate of extension if an average rate of strain defined by ϵH = 1/t ln(l/l0) is used.
Crease recovery and cuprammonium solubility of some crosslinked cotton fabrics
Authors: Head Frank S. H.
Published: April 2003

Cotton fabrics crosslinked with the pyridinium salts of three di(chloromethyl) ethrse become largely insoluble in cuprammonium hydroxide solution and their wet and dry crease recovery increases. The solubility falls to below 40% under all the conditions studied. Good improvements in crease recovery are observed only when solubility is below 4%, but the reverse does not hold; some fabrics of poor crease recovery may also have low solubility.
Stress–strain behavior of SAN/glass bead composites above the glass transition temperature
Authors: Narkis M. , Nicolais L.
Published: April 2003

Relaxation and stress–strain behavior of SAN–glass bead composites are studied above the glass transition temperature. The strain imposed on the polymeric matrix of the composite is defined as ϵp = ϵc/(1 − ϕ⅓). Stress relaxation data for the filled polymer which is independent of strain can be calculated by multiplying the relaxation modulus (at a certain strain) by (1 + ϵp). Stress–strain curves at constant strain rate and for different concentrations of the filler can be shifted to form a master curve independent of filler content if the tensile stress is plotted versus ϵp. The relaxation modulus increases with increasing the filler concentration and can be predicted by a modified Kerner equation at 110°C.
Studies on adhesion of allylic resin. III. Rheological treatment for the adhesion of diallyl phthalate resin
Authors: Nara Shigeo , Matsuyama Kentaro
Published: April 2003

Rheological treatment was carried out for the joining system of diallyl phthalate resin and dichromate‐treated copper foil. Rotational and diffusional segmental motions in the diallyl phthalate molecule are required to obtain the necessary bonding strength, and this consideration was confirmed by Kanamaru's setting rate theory. Furthermore, the bonding strength was dependent on the setting temperature and time, and these results were investigated by the dynamic properties of diallyl phthalate resin.
The helical structure of cellulose I
Authors: Viswanathan A. , Shenouda S. G.
Published: April 2003

The unit cell dimension along the crystallographic b‐axis of cellulose is widely accepted to be 10.3 Å, as against the distance of 10.3912 Å between the terminal oxygen atoms of a cellobiose molecule, estimated from the now well‐established crystal structure of cellobiose. Since cellulose is only a polymer of the cellobiose residue, it has been possible to derive the crystal structure of cellulose I from that of cellobiose. The strict application of stereochemical principles to the sucessive residues in the cellulose chain and a consideration of the formal geometric characteristics of a helix suggest a helical form to the cellulose molecule, with seven cellobiose residues per turn, radius r = 1.5830 Å, and angle of helix 7°51′ which is close to the x‐ray orientation angle of 8°21′ observed in ramie, the best‐oriented native cellulose. An analysis of intensity data both for the equatorial and for the meridional reflections leads to a unit cell with central reversed and corner chains and a relative shift between them of one fourth of the repeat length along the b‐axis.
Gel permeation chromatography: Physical characterization and chromatographic properties of corning porous glasses
Authors: Cooper A. R. , Bruzzone A. R. , Cain J. H. , Barrall E. M.
Published: April 2003

Five porous glasses, manufactured by Corning, reputed to have very narrow pore size distributions, have been characterized by mercury porosimetry, nitrogen adsorption–desorption isotherms, and electron microscopy. The characteristics of these glasses as packing materials in gel permeation chromatography have been determined. Using polystyrene solutes and toluene solvent at room temperature, the glasses in series combination of columns are capable of separating molecular weights from a few thousand to several million. These glasses are compared with other available materials for column packings in gel permeation chromatography.
The conversion of ethylene–vinyl acetate copolymers with aluminum alcoholates
Authors: Rätzsch M. , Schade H. , Pabst P.
Published: April 2003

If ethylene–vinyl acetate copolymers are converted with aluminum alcoholates, crosslinked products will form. This reaction was studied on the basis of the viscosity variation and the amount of acetic acid ester formed. The constants of the reaction velocity for the conversion with various aluminum alcoholates were determined and a reaction mechanism is discussed.
Turbulent flow friction reduction effectiveness and hydrodynamic degradation of polysaccharides and synthetic polymers
Authors: Kenis Paul R.
Published: April 2003

Two water‐soluble synthetic polymers and several polysaccharides were compared for friction reduction effectiveness during increased exposure to turbulent flow. Solutions were passed through a 0.117 × 41.0 cm fine bore tube at a constant solvent wall shear stress of 4200 dynes/cm2 and wall shear rate of 4 × 105 sec−1. After one pass through the tube, greatest friction reduction at low polymer concentrations was in the order poly(ethylene oxide) > polyacrylamide > bacterial polysaccharide from Xanthomonas campestris > guar gum. As a result of mechanical degradation, after 40 passes of 40 ppm solutions, friction reduction effectiveness was in the order polyacrylamide > polysaccharide from Xanthomonas campestris > poly(ethylene oxide) > guar gum. Degradation curves, the effect of concentration on degradation, and boundary layer and pipe flow applications are discussed.
Molded neoprene liner pads for the poseidon missile launcher
Authors: Meier J. F. , Minter H. F. , Connors H. J.
Published: April 2003

Neoprene formulations and mechanical designs have been developed to meet special operational requirements for the Poseidon Missile Launch System liner. The liner supports the missile in an aligned position, provides shock mitigation, reacts properly with the missile during launch, and damps vibrations. Operational requirements include static and dynamic compressive stiffness, damping, and water drainability. A mechanical design was evolved that utilized notched, prebuckled struts as supporting members. Compression–deflection characteristics were modified by simultaneous changes in geometrical design and polymer formulation. A study of the effects of variations in polymer compounding and mechanical design on the compressive stiffness, rate sensitivity of the compression–deflection characteristics, and vibrational damping is described. Mold release agents and their role in successful production are discussed.
The fracture toughness and stress corrosion cracking characteristics of an anhydride‐hardened epoxy adhesive
Authors: Mostovoy S. , Ripling E. J.
Published: April 2003

The toughness and stress corrosion cracking characteristics of an epoxy resin (DER 332) hardened with hexahydrophthalic anhydride (HHPA) were investigated. The epoxy was studied in both the bulk and bond form, and its properties were compared with an amine‐hardened (tetraethylene pentamine, TEPA) system. The toughness, 𝒢Ic, of the anhydride system varied less as a function of ratio of hardener‐to‐resin content and postcure temperature than it did in the TEPA‐hardened system. Like the latter, however, its toughness in the bulk and bond forms could not be correlated, but 𝒢Ic of the joints was dependent on tensile modulus and/or yield strength of the bulk epoxy. Both systems were also toughened in the vicinity of the crack tip by water for short‐time loading, but their long‐time load carrying capability was reduced by a water environment. The anhydride hardened system was more sensitive to strength loss in water than the amine system. The fracture morphology for the two systems was the same, i.e., fast cracking occurred cohesively near the center of the bond, and slow cracking occurred at the interface.
Effect of joint geometry on the toughness of epoxy adhesives
Authors: Mostovoy S. , Ripling E. J.
Published: April 2003

Increasing joint thickness was shown to increase the toughness of epoxy joints hardened with either tetraethylenepentamine (TEPA) or hexahydrophthalic anhydride (HHPA). The increased toughness was associated with a marked increase in macroroughness. An upper limit of joint thickness and hence toughness occurred because very thick joints could not be produced. Residual stresses developed during cooling from the curing temperature caused the latter to separate at the interface. Stress corrosion cracking resistance was also found to depend on bond thickness. For the TEPA‐hardened system, bond thickness had only a minor influence for thicknesses up to 25 mils; and for the HHPA‐hardened system, this persisted to bond thickness of 50 mils. Further increases in bond thickness for both systems caused an abrupt rise in resistance to stress corrosion cracking.
Determination of concentration changes on membrane surface as function of time during evaporation of reverse‐osmosis film casting solutions
Authors: Ohya Haruhiko , Sourirajan S.
Published: April 2003

Data on the activity of acetone for the binary system acetone‐formamide, and a specific ternary system cellulose acetate‐acetone‐formamide are given for the temperature range 0 to 30°C. A method of determining concentration changes occurring on the membrane surface during the evaporation stage in the process of making cellulose acetate reverse osmosis membranes is illustrated.
Pyrolysis of treated rayon fiber
Authors: Duffy James V.
Published: April 2003

The thermal decomposition behavior of rayon yarn which had been treated with various chlorosilanes and boron–phosphorus compounds was determined at temperatures up to 800°C. It was found that 70% of the available hydroxyl groups in rayon would react with dichlorodiphenylsilane and that the treated yarn had an initial decomposition temperature 125°C higher than that of untreated rayon. The weight loss of the treated yarn at 800°C was dependent on the nature of the chlorosilane and the type of posttreatment used. Alkylchlorosilanes produced higher weight losses than did the arylchlorosilane‐treated rayons. Treatment of rayon yarn with bis(chlorodiphenyl‐phosphine)decaborane (BCDPD) or dimeric chlorophospha(III)‐o‐carborane (DCPC) resulted in an increase in the char yield of the pyrolyzed yarns. In the case of untreated rayon, weight retention at 800°C was 20%, whereas the treated yarns yielded boronated residues of 42–53%. Carbon yields as high as 28% were obtained with the BCDPD treatment. This treatment also resulted in substantial improvement in the oxidative stability of rayon at temperatures up to 250°C.
A structure–property rationalization of some poly(carboxyl–epoxy) thermosets
Authors: Fellers J. , Golovoy A.
Published: April 2003

The glass transition temperatures, Tg, and strength properties have been determined for an acrylic‐based prepolymer containing 25 mole‐% carboxyl functionality crosslinked with five different diepoxides. The Tg values vary from 100° to 200°C, and ultimate elongations of 2% to 7% at 25°C are observed with the different crosslinking agents. These variations are rationalized in terms of the structural elements present in the diepoxides. Thermosets possessing rigid structural units at the crosslink points connected by flexible segments have the best all‐around combination of Tg and tensile properties. A decline in these properties was noted when the epoxide/carboxyl ratio exceeded unity owing to the formation of mixed networks and free chain ends.
Radiation protection of poly(vinyl chloride) by N‐methyl dithiocarbamate substitution
Authors: Nakagawa Tsutomu , Hopfenberg H. B. , Stannett V.
Published: April 2003

The effect of N‐methyl dithiocarbamate substitution on the radiation stability of poly‐(vinyl chloride) (PVC) films was studied. PVC containing between 2 and 11 mole‐% N‐methyl dithiocarbamate (PMD) was irradiated with γ‐rays from a 60Co source at 40°C and the evolved gaseous products were measured and analyzed with a mass spectrometer. The apparent G values for gas evolution for PMD decreased remarkably. For example, a G value of 0.28 was obtained for a PMD which contains 11 mole‐% dithiocarbamate group compared with a G value of 10.8 for unmodified poly(vinyl chloride). Furthermore, the mass spectrum of the evolved gas from the same PMD sample (PMD‐44) with 10 Mrad irradiation showed no hydrogen chloride to be present. The external protection was studied using polymer‐blended films of PVC and PMD‐44. The stabilization coefficients for internal protection and external protection in polymer blends were calculated. The ESR spectrum of the irradiated PMD‐44 showed a strong anisotropy with high g values which differed significantly from the spectrum of the irradiated PVC. A suggested mechanism for radiation protection of PVC against γ‐rays irradiation by the N‐methyl dithiocarbamate group is discussed.
Light scattering properties of acacia catechuic acid. Effects of urea and temperature
Authors: Chakravorty J. N.
Published: April 2003

Association of acacia catechuic acid (ACA) molecules was established in ethanol–water medium2. This association was further tested in pure aqueous medium as well as by using urea in increasing amounts in aqueous solutions. The 5M urea depressed the molecular weight to 2.82 × 106, as against 5.04 × 106 in aqueous solution of NaCl or KCl. This reduction has been explained as due either to rupture of the molecule itself or dissociation of molecules which normally remain associated in water. The diminution of root‐mean‐square end‐to‐end distance in urea from 323 mμ in water3 to 290 mμ has also been attributed to the disaggregation of the associated molecules. To test this point further, the effect of increasing the temperature was next studied. The molecular weight was observed to be lower at higher temperature (actual value at 47°C was nearly half the original value at 28°C). This considerable reduction positively points to a dissociation of the molecule which was first suspected in our study with urea. The root‐mean‐square end‐to‐end distance also diminished to a certain extent, but not so much as the molecular weight. This has been explained as due to the stretching of the molecule when the solvent behaves as a better solvent at higher temperature.
Preparation and properties of poly(acrylic acid) composite membranes
Authors: Sachs S. B. , Lonsdale H. K.
Published: April 2003

A new type of membrane has been prepared for hyperfiltration (reverse osmosis) desalination that is essentially a very thin polyelectrolyte membrane. It is prepared by casting an aqueous solution of a polyelectrolyte, specifically poly(acrylic acid) (PAA), directly on one surface of a finely porous support membrane. In hyperfiltration tests, these composite membranes exhibit desalination performance comparable in dilute solutions to that observed with cellulose acetate membranes of the Loeb‐Sourirajan type. The water flux through these membranes is linear in the pressure up to 100 atm. Salt rejection is a function of pressure; it is also a function of the concentration of the feed solution and the charge of the counterion, in qualitative agreement with the Donnan ion‐exclusion mechanism. Typical long‐term results range from water fluxes of 2 × 10−3 g/cm2‐sec (50 gal/ft2‐day) and 80% salt rejection to 0.2 × 10−3 g/cm2‐sec (5 gal/ft2‐day) and >99.5% salt rejection at 1500 psi with 0.3 wt‐% NaCl. These membranes appear to be useful for brackish water desalination.
A rationale for the preparation of Loeb‐Sourirajan‐type cellulose acetate membranes
Authors: Strathmann H. , Scheible P. , Baker R. W.
Published: April 2003

An attempt has been made to rationalize the variables in the preparation procedure of Loeb‐Sourirajan‐type reverse‐osmosis membranes. The quaternary phase diagram of the system cellulose acetate–acetone–formamide–water was determined and has proved a useful tool in the discussion of membrane structures and properties. A mechanism based on differences in the precipitation rate of the polymer during the membrane formation process has been suggested to explain the observed asymmetry in the membrane structure. The porosity of the membrane has been ascribed to the relative rates of water entering and solvent leaving the cast film. The effects of the casting solution composition, the evaporation time, the wash bath temperature, and the annealing procedure have been studied. X‐Ray diffraction and electron microscopy were used to supplement flux and retention data of membranes made from a cellulose acetate–formamide–acetone casting solution.
Environmental stress relaxation studies of polymers: Effect of temperature on polyethylene–alcohol system
Authors: Nisizawa Mizuho
Published: April 2003

The method of stress relaxation has been used to study the plasticizing effect of sorbed alcohols on polyethylene as it changes with temperature. From the observation of the stress relaxation in polyethylene under alcohols at various temperatures, the activation energy of penetrant‐enhanced relaxation of polyethylene caused by alcohols was obtained.
Pyrolysis products of untreated and flame retardant‐treated α‐cellulose and levoglucosan
Authors: Wodley Frank A.
Published: April 2003

A typical gas chromatogram of the volatile pyrolysis products of untreated α‐cellulose contains 39 peaks; however, mass spectral data indicate that at least 59 compounds, with molecular weights less than about 150, are present. A total of 37 compounds have been identified, 13 of which have not been previously reported. Most of the newly identified compounds contain a benzene ring, indicating that these compounds may be products of reactions between initial volatiles. A comparison of the products generated in the temperature range of 330°–440°C indicates that the formation of pyrolysis products is essential independent of temperature. Comparisons of the chromatograms obtained for untreated levoglucosan and cellulose indicate that most of the decomposition of cellulose probably forms levoglucosan which then decomposes to yield the observed pyrolysis products. In addition, the products of flame retardant‐treated levoglucosan are essentially the same as those of cellulose with the same retardant treatment. This suggests that the retardants act on the levoglucosan formed in the decomposition of the cellulose rather than on the cellulose directly.
Fracture toughness of glass fiber‐reinforced acetal polymer
Authors: Hardy G. F.
Published: April 2003

The critical stress field intensity factor for crack propagation,KIc, was determined for a large number of glass fiber‐reinforced acetal copolymer compositions and for the unfilled resin. The results were interpreted in terms of a model previously proposed for the tensile behavior of these materials. TheKIccould be regarded as a linear function of the contribution of the fiber reinforcement to the tensile strength, but was otherwise substantially independent of the amount and length of the fibers and the nature of the fiber finish. From this relationship it was estimated that the inherent flaw size of these materials was of the order of magnitude of the fiber length. The observed variation ofKIcwith loading rate was also consistent with the model. The notched Izod impact strength of these same materials was shown to be roughly equivalent toGIc, the critical strain energy release rate, or fracture energy per unit area, which can be computed fromKIcby the methods of fracture mechanics. The behavior of these crack propagation parameters is consistent with the previous hypothesis that failure is initiated by loss of adhesion between the matrix and those fibers which lie transverse to the applied load.
Polymers containing the s‐triazine ring. II. Synthesis of poly(s‐triazinylenehydrazones)
Authors: Oikawa Eizo , Tatsuishi Hirofumi
Published: April 2003

Poly(2‐methyl‐ or 2‐phenyl‐s‐triazinylenehydrazones) were prepared both by dehyhydration of dihydrazino‐s‐triazines with terephthalaldehyde and by dehydrochlorination of dichloro‐s‐triazines with terephthalaldehyde dihydrazone. The structure of the polymers was confirmed by infrared spectrometry and elemental analyses in comparison with those of a model compound. Dehydration yielded soluble polymers, while the dehydrochlorination yielded insoluble polymers. Most of the polymers degraded at about 350°C, and the polymers of higher molecular weight showed better thermal stability. The thermal behavior of the polymers indicated that the phenyl‐substituted polymers obtained by dehydrochlorination and the methyl‐substituted polymers obtained by dehydration had a degree of polymerization similar to that of the phenyl‐substituted polymers obtained by dehydration. The soluble polymers could form chelate polymers, these took two accelerated decomposition phases. The lower phase suggested a decomposition accelerated by a metal. The higher phase, in which the chelate polymers decomposed more rapidly at a higher temperature (above 400°C) than their ligand polymer, was related to the atomic number and the electro‐negativity of the metals. The formation of decomposition products, guanamines and nitrile compounds, in all cases indicate the preferential scission of nitrogen‐nitrogen bonds.
Degradation of polymers by high‐speed stirring
Authors: Nakano Akihiko , Minoura Yuji
Published: April 2003

Benzene solutions containing either poly(ethylene oxide) or poly(methyl methacrylate) or both of varying concentrations were prepared, stirred at a speed of 30,000 rpm, and the effects of concentrations of the same species or different species of polymers on the degradation of the polymers were investigated. Within experimental error little difference was observed in the [η] curves measured for each degraded polymer in spite of change in concentration. It is clear that the degradation of polymer with high‐speed stirring in the concentration range 1–4% w/v is not caused by the interaction of polymer chains.
Study of the oligoester maleinates containing an isocyanuric ring by infrared spectroscopy
Authors: Alaminov H. , Proynova Z.
Published: April 2003

Processes taking place in crosslinked oligoester maleinates containing an isocyanuric ring were studied by means of infrared and ESR spectroscopy and heating from 110° to 600°C. By determining the optical density of the carbonyl groups at 1690 cm−1, of the CH2 groups at 1460 cm−1, ether and ester groups at 1120 and 1260 cm−1, and vinyl groups at 935 and 990 cm−1, their mutation by hardening and tempering of the polymers was followed. The investigation shows that the carbonyl absorption of the oligoester maleinates containing an isocyanuric ring is double and that of the oligoester propylene‐glycol maleinate phthalate is single. By modification of the isocyanuric oligoester maleinates with phthalic, adipic, sebacic, and other acids, and increase of the speed of isomerization of maleric groupings to fumaric is observed. By building of isocyanuric links in oligoester maleinates, a more stable structure is obtained. Above 330°C, isocyanuric links probably regroup into polycyanic links. The typical carbonyl absorption precipitously decreases at 400°C and disappears altogether at 600°C. On the basis of the investigations carried out, it is assumed that, in the process of hardening and thermodestruction of the polymers investigated, and radical processes obviously play an essential part
A study of the fine structure of cellulosic fibers by level‐off degree of polymerization measurements
Authors: Zeronian S. H.
Published: April 2003

The crystallization of disordered and partly disordered cellulose on hydrolysis with boiling dilute mineral acid was studied and the level‐off degree of polymerization (LODP) of cotton after treatment with inter‐or intracrystalline swelling agents was determined. The LODP, of cotton and of cotton which had been swollen in morpholine were similar, indicating that the LODP of cotton cellulose was not affected by this intercrystalline swelling agent. It appears that the aggregates of cellulose chains present in cotton which has been treated with aqueous NaOH of mercerizing strength and then washed with water are not uniformly accessible to hydrolyzing acid and that the accessibility to the acid is not changed when the cellulose is dried. The LODP of samples of mercerized, ethanol‐washed, never‐dried cotton that had been acetylated was obtained and the results are discussed in terms of current views on the fine structure of cotton.
Deposition of acrylate polymers in wool fibers
Authors: Simpson W. S.
Published: April 2003

The factors influencing the kinetics of formation of acrylate polymers in wool fibers are described. Allyl methacrylate and N,N′‐methylenebisacrylamide were found to copolymerize satisfactorily with methyl or ethyl acrylate to form crosslinked polymers. Conditions were found for almost complete conversion of the available monomer to polymer in a batch‐type process.
Intercrystalline crosslinking of polyethylene
Authors: Brody H.
Published: April 2003

The heat distortion temperature (British Standards Method 102C) and DTA nominal melting point of high density polyethylene have been raised to 140°C by nonrandom crosslinking in which the crosslinks are superimposed on the existing semicrystalline structure. The crosslinking agent was a mixture of dicumyl peroxide and allyl methacrylate, and the crosslinking temperature was 120°C, just below the crystal melting range. In contrast, random crosslinking by the same system above the melting range at 160°C lowered the HDT (heat distortion temperature). Conventional peroxide crosslinking also lowered the HDT. The gel swelling of randomly crosslinked polyethylene was higher than that of nonrandomly crosslinked polyethylene having the same gel content. This dependence of the gel swelling on the crosslink distribution can be correlated with the HDT. The effect of γ‐radiation and carbon black loading on the HDT has also been studied.
Graft copolymerization of vinyl monomers on modified cottons. III. Grafting of acrylonitrile and methyl methacrylate on cyanoethylated cotton by the ceric ion method
Authors: Kantouch A. , Hebeish A. , El‐Rafie M. H.
Published: April 2003

The interaction of acrylonitrile and methyl methacrylate with cyanoethylated cotton in the presence of ceric ion has been studied under a variety of conditions. Increasing the reaction time, the monomer concentration, and the temperature favorably influences the degree of grafting. The same holds true for initiator concentration up to a certain limit, after which a decrease in the graft yield was obtained. On the other hand, ceric consumption during grafting and oxidation increases by increasing the magnitudes of all these factors. However, the consumption during grafting is always higher than that during oxidation. The graft yields obtained with cyanoethylated cotton are greater than those of the control, being increased by increasing the degree of substitution (D.S.) of the cyanoethylated cotton, suggesting that the cyanoethyl groups afford additional sites of grafting. On the other hand, the ceric consumption during oxidation of cyano‐ethylated cotton was much lower than that of the control, being increased also by increasing the D.S., indicating perhaps that ceric ion attacks the cyanoethylated cotton exclusively at the cyanoethyl groups. Based on these findings, a scheme for the mechanism of reaction of a vinyl monomer with cyanoethylated cotton was proposed.
Predicting joint sealant performance of elastomers by computer simulation. III. Simulation of single‐ and multi‐step extension of a stress‐relaxing material
Authors: Catsiff E. H.
Published: April 2003

Computer simulation of the extension of a joint seal that had fully relaxed in a compressed configuration indicated that exceptionally high stresses were engendered if the extension occurred in a single step, as provided in certain “performance tests.” When the same amount of extension was simulated by a stepwise procedure, with the assumption of full relaxation after each step, not only were the stresses smaller, but the stress concentration factors in the extreme corners of the joint seal were much reduced, so that the likelihood of failure under such conditions would appear to be remote. This stepwise extension pattern is considered to be more representative of real joint behavior than the “accelerated performance test.”
Effects of symmetrical bonding defects on tensile shear strength of lap joints having ductile adhesives
Authors: Schonhorn Harold , Ryan F. W. , Wang Tsuey T.
Published: April 2003

In this paper we examine the effect on joint strength of depleting the bond line of a relatively flexible adhesive (polyethylene) while maintaining a constant adhesive film thickness. It is shown that the tensile shear strength of a lap specimen is not governed by edge effects but rather by the bonded area. By using limit analysis of the plasticity theory, we demonstrate why the tensile shear strength of the joint is insensitive to stress concentrations at the bonding defects.
The chemistry of furfuryl alcohol resins
Authors: Barr J. B. , Wallon S. B.
Published: April 2003

Furfuryl alcohol resins contain a broad spectrum of compounds. The distribution of these compounds in a given resin varies with the manufacturing conditions. A resin containing a high proportion of low molecular weight constituents has been prepared and separated into fractions. Twelve compounds were separated from the resin; four of these are new compounds. The lower molecular weight constituents can be arranged into four major classes: polyfurfuryl alcohols, polyfurfuryl furans, methyl‐substituted polyfurfuryl furans, and polyfurfuryl ethers.
The influence of precure dilation on the stress–strain properties of ethylene–propylene terpolymer networks
Authors: Kirkham M. C.
Published: April 2003

A study has been made of the influence of a dilating liquid, present during vulcanization, on the stress–strain behavior of EPT vulcanizates. Stress–strain measurements performed on the vulcanizates after extraction of the dilating liquid, taken over a range of strain rates, indicate the effective absence of time‐dependent behavior and suggest that a close approach to equilibrium has been achieved. From the experimental data, values of the C1 and C2 constants of the empirical Mooney‐Rivlin equation were derived. It was found that both C1 and C2 decreased with increased precure dilation, C2 decreasing more rapidly than C1. The observed decrease in C1 is less than would be predicted by simple analogy with the Gaussian modulus; it is suggested that this difference might be explained by changes in network configuration and topology associated with the precure dilation.
Optimization of the filler content of filled polyester resin
Authors: Jones W. C. , Fricke A. L.
Published: April 2003

A method for the constrained optimization of the filler content in polyester resin was demonstrated. The fillers investigated included marble, clay, pecan shell flour, and hollow microspheres in various concentrations. The method of optimization included an experimental design to generate data and a polynomial regression analysis to determine the mechanical property constraint functions. The constraints were well approximated by linear functions, and linear programming was used to find optimum compositions for several possible applications.
ESR study of intramolecular energy transfer in the radiolysis of cellulose thenoates
Authors: Singh Sujan , Hinojosa Oscar , Arthur Jett C.
Published: April 2003

The substitution of 2‐thenoyl, 5‐methyl‐2‐thenoyl, 2‐thiopheneacryloyl, 5‐bromo‐2‐thenoyl, and 5‐bromo‐2‐thiopheneacryloyl groups on fibrous cotton cellulose increased the radiation resistance of cellulose, as indicated by the retention of the breaking strengths of the modified fibrous celluloses at high dosages of γ‐radiation, as compared with that of irradiated, unmodified fibrous cellulose. The presence of electropositive or electronegative substituents on the thiophene groups did not reduce the radioprotective effects of these groups for cellulose. Crosslinking of the cellulose thenoates in 1,3‐di(4‐pyridyl)‐propane did not significantly reduce the radiation resistance of the thenoates. Examination of the ESR spectra of irradiated cellulose and cellulose thenoates indicated that the site of the long‐lived free radicals on the irradiated cellulose molecules was not changed by the chemical modification. However, the concentration of long‐lived free radicals in irradiated cellulose thenoates, at a given radiation dosage, was less than that in irradiated cellulose. The localization of energy on carbon C1 or C4 of the cellulose molecule, which leads to depolymerization and loss in breaking strength of fibrous cellulose, was decreased. The radioprotective effects of thiophene groups for cellulose were similar to those of furan and benzenoid groups.
Rheological properties of molten polymers. II. Two‐phase systems
Authors: Han Chang Dae , Yu Thomas C.
Published: April 2003

A study is carried out for characterizing two‐phase systems of molten polymers by their viscous and elastic properties. The two‐phase systems chosen for study are blends of polystyrene and polypropylene, and blends of polystyrene and high‐density polyethylene. For the study, measurements of wall normal stresses are made by use of a capillary melt rheometer described in part I of this series. The concept of the “exit pressure” is used to determine the elastic properties of the two‐phase polymer systems. The present study shows anomalous viscous and elastic properties of two‐phase systems, which are difficult to predict from knowing the viscous and elastic properties of their individual components. A detailed discussion is given on the state of dispersion of two incompatible polymer systems in the molten state, by presenting pictures of the microstructure of the extrudate samples. The state of dispersion appears to vary depending on the blending ratio, extrusion temperature, melt viscosities of individual components, and blending method.
Molecular weight distribution and rheological properties of polyisobutylene solutions
Authors: Nishida Noboru , Salladay David G. , White James L.
Published: April 2003

The molecular weight distribution of a series of polyisobutylenes was determined using osmotic pressure measurements, gel permeation chromatography, and intrinsic viscosity. All of the polymers except for one, a blend of the highest and lowest molecular weight constituents, had similar moderate molecular weight distributions. The “extended chain length” method of calibrating the gel permeation chromatograph for polyisobutylenes was found to be effective. Steady state and transient shear stresses and normal stresses were measured on 5% decalin solutions of these polymers. The zero shear viscosity increased with the 3.3 power of molecular weight, and the zero shear normal stress coefficient (σ11 − σ22)/Γ2 varied with the 7.5 power. Relative elastic memory as measured by (σ11 − σ22)/σ12 or stress relaxation increased with increasing molecular weight (and at constant number‐ or weight‐average molecular weight) with breadth of distribution. Stress overshoot also correlated with this tendency.
The mechanical behavior of microporous polyurethane foams
Authors: Whittaker R. E.
Published: April 2003

The mechanical behavior of microporous polyurethane foams used in poromeric materials can be described by use of a model comprising of struts of square cross section arranged in a cubical lattice. The model was initially proposed by Gent and Thomas to describe the properties exhibited by natural rubber latex foams. The microporous polyurethane foams used in poromerics are in general much stronger than natural rubber foams, and it has been found that their tear and tensile properties are dependent on the size of the largest pore, which can be up to 20 times greater in diameter than the average pore size. The behavior of the polyurethane foam in compression can be satisfactorily described by use of this cubical model and shape factor theories from polymer engineering.
Polymer miscibility in organic solvents and in plasticizers—a two‐dimensional approach
Authors: Chen Show‐An
Published: April 2003

From thermodynamic considerations based on associated solution models and from the Hansen's three‐dimensional solubility parameter concept, it is found that the solvent power of an organic liquid for a given polymer can be characterized by two parameters, δh and χH, where δh is the hydrogen‐bonding solubility parameter of the liquid, and χH is a term which takes account of the dispersion and polar interactions between the liquid and the polymer and of the effects due to temperature and molecular size of the liquid. It is also found that Hansen's solubility sphere for the polymer can be represented as a solubility circle in the proposed χH−δh plane. The proposed approach is applied successfully to polymer–plasticizer systems.
Compressibility of polyethylene melts at low pressures
Authors: Chung Chan I.
Published: April 2003

Branched polyethylene has quite different rheological and physical properties from its linear homologue. Despite their many different properties, the densities of linear and branched polyethylene melts at atmospheric pressure have been reported to be identical at all temperatures. However, it was not known whether their melt densities at a given temperature would also be identical at all pressures. In this investigation, the compressibilities of one linear and two branched polyethylene melts at 160°C, 190°C, and 220°C were studied, and it was found that they had an identical compressibility over the present experimental pressure range of ca. 0–455 psi (0–31 atm). Both the specific volume and the density at each temperature could be very accurately expressed as linear functions of pressure for this pressure range. Time‐dependent compressive property was not observed within the present low pressure range.
Structure–physical property relationships in peroxide‐cured butadiene–styrene copolymers
Authors: Ambrose R. J.
Published: April 2003

Structure–physical property relationships in high‐vinyl butadiene–styrene copolymers have been determined for samples cured with dicumyl peroxide under the same conditions. Three different structures, butadiene–styrene–butadiene (B–S–B) triblocks, butadiene–styrene (B–S) diblocks, and random butadiene–styrene copolymers, have been examined. Flexural modulus increases with increasing styrene content owing to the inherent stiffness of a polystyrene backbone. Swelling increases whereas hardness and heat distortion temperature decrease with increasing styrene content. This behavior is explained by the decrease in crosslink density with increasing styrene content in all structures. Heat distortion temperatures of the B–S–B and B–S networks are superior to the heat distortion properties of the random structures. The B–S–B structure is the most solvent resistant, followed by the random copolymers, with the B–S structures swelling to the greatest extent. Swelling differences between the B–S–B and random networks decrease with increasing styrene content, while swelling differences between the B–S–B and B–S networks increase with increasing styrene content. These results are explained by the nature of the crosslinking reaction and the number of loose ends present in each network.
Studies on the development of improved reverse osmosis membranes from cellulose acetate–acetone–formamide casting solutions
Authors: Pilon Rachel , Kunst B. , Sourirajan S.
Published: April 2003

Improved membranes from cellulose acetate–acetone–formamide casting solutions have been prepared for low‐pressure reverse osmosis applications. The film‐casting details for one such type of membranes (Batch 400) are as follows. Casting solution composition: cellulose acetate (E‐398‐3), 17 wt‐%, acetone, 56 wt‐%, formamide, 27 wt‐%; temperature of casting solution, 24°C; temperature of casting atmosphere, 24°C; casting atmosphere, ambient air in contact with 30 wt‐% acetone in aqueous solution; solvent evaporation period, 30 sec; gelation medium, ice‐cold water. Using aqueous feed solutions containing 3500 ppm of NaCl, the product rates obtained with the above membranes at 95, 90, and 60% levels of solute separation were 15.9, 22.1, and 58.7 gallons/(day ft2), respectively, at 250 psig under feed flow conditions corresponding to a mass transfer coefficient of 45 × 10−4 cm/sec on the high‐pressure side of the membrane. The effects of casting solution composition, presence of acetone in the casting atmosphere, evaporation period, evaporation rate constant, and the remoteness of casting solution composition from the corresponding phase boundary composition on membrane performance and shrinkage temperature profile were found to be similar to those reported earlier for membranes obtained from cellulose acetate–acetone–aqueous magnesium perchlorate casting solutions. The results illustrate the practical utility of the approach based on the solution structure–evaporation rate concept for creating more productive reverse osmosis membranes.
Time and temperature dependence of the mechanical properties of polystyrene bead foam
Authors: Rinde J. A. , Hoge K. G.
Published: April 2003

Tensile and compressive properties of polystyrene bead (PSB) foams at room temperature for strain rates from 10−3 to 105 min−1 can be represented as nearly linearly increasing functions of modulus or stress versus the logarithm of the strain rate. The shear modulus and tensile data, including failure properties, on 0.054 g/cc PSB foam at various temperatures and strain rates can be represented by master curves of log (stress or modulus) versus log (reduced strain rate). These master curves are formed by a time and temperature superposition method, wherein data at one temperature are superposed on data at another temperature by a shift along the log (strain rate) axis. These time–temperature shift factors are calculated using a form of the Arrhenius equation.
An x‐ray study of crystalline orientation and mechanical properties of swollen cotton fibers using cadoxen solution as swelling agent
Authors: Varma D. S. , Bhatia H. C.
Published: April 2003

Bundles of cotton fibers were given swelling and stretching treatment using Cadoxen solution containing 3.58% cadmium. The fibers were stretched from −2% to +8% in steps of 2%. The crystallite orientation and mechanical properties of treated fibers are markedly improved. Results clearly indicate that the swelling of cotton in Cadoxen solution is intercrystalline and the swollen fiber has retained the cellulose I structure.
A study of the low molecular weight components of furfuryl alcohol polymers
Authors: Wewerka E. M. , Loughran E. D. , Walters K. L.
Published: April 2003

Low molecular weight components of both an acid‐polymerized and a γ‐alumina polymerized furfuryl alcohol polymer were separated by gas chromatography utilizing a Porapak type P‐S column packing. The identities of the separated polymer components were established by infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance analysis. Volatile constituents found to be common to both furfuryl alcohol resin types were: furfuryl alcohol, water, difurylmethane, difurfuryl ether, and 2,5‐difurfurylfuran. Also, 5‐furfurylfurfuryl alcohol was found to be present only in the acid‐polymerized resin, and 4‐furfuryl‐2‐pentenoic acid γ‐lactone was a constituent only of the γ‐alumina‐polymerized resin. Contrary to expectation, no esters of levulinic acid were found among the low molecular weight components of the γ‐alumina‐polymerized furfuryl alcohol polymer.
Visible dichroism of polypropylene–disperse dye system at high temperatures
Authors: Nakayama Kazuo , Okajima Saburo , Kobayashi Yasuji
Published: April 2003

The dichroism of polypropylene film dyed with C. I. Disperse Yellow 7 was investigated at various temperatures up to 160°C. The dichroic value D drops as the temperature is raised. So long as the amorphous structure does not change irreversibly, D changes reversibly with temperature. The experimental results agree qualitatively with those obtained on poly(ethylene terephthalate) in our previous paper, although the effect of temperature on the extent of the reversible change in D is larger in PP than in PET. The plot of D versus temperature exhibits breaks at 40°–50°C (T0), 70°–80°C (T1), and 115°–120°C (T3). These temperatures agree with the transition points of polypropylene in the literature. From the change in the intrinsic dichroism D0 with temperature, it is concluded that the decrease in D at high temperatures is due to the drop of D0 caused by the disorientation of dye molecules in the amorphous region, while the amorphous polymer chain is not disoriented. Such a conclusion is supported by the fact that Δn of a heat‐set specimen is kept constant during heating, in contrast to D.
Influence of compacting pressure on the permeability of vectorized membranes for liquids
Authors: Peterlin A. , Williams Joel L.
Published: April 2003

The theory of liquid diffusive flow through graded membrane under applied pressure difference is developed and demonstrated on four simple models. The grading of the membrane, caused by a gradient of chemical composition or physical structure, results in a gradient of liquid uptake (hydration) which in turn is reduced by the compacting pressure existing in the membrane during the permeation experiment. The hydration established in equilibrium between the swelling tendency and compacting pressure determines the local permeability. It has different values K+ = K− for opposite flow direction. The total membrane permeability 〈K〉, however, depends on the current direction only in the case that the relative depression of local hydration, and hence of permeability by pressure, is not uniform but has a gradient. In mathematical formulation, the directionality of membrane requires the local permeability to be an irreducible function of location and pressure p, continuously increasing or decreasing with x. Th permeability of the membrane is higher if the driving pressure is applied at the side of the membrane with higher relative reduction of hydration and permeability by compacting pressure.