bluuebunny/crossref_metadata_2025 huggingface dataset:
Photopolymerization of acrylonitrile sensitized with a combination of aromatic ketone and amine
Authors: Kubota Hitoshi , Ogiwara Yoshitaka
Published: April 2003

Effect of amines on photopolymerization of acrylonitrile sensitized with various sensitizers was investigated in N, N‐dimethylformamide at 30°C. Photopolymerizations sensitized with aromatic ketones such as benzophenone (BP), fluorenone (Fl), acetophenone, and Michler's ketone were noticed to be activated by triethylamine (TEA). Diethylamine, tri‐n‐butylamine, di‐n‐butylamine, and n‐butylamine besides TEA also proved to be effective for the system sensitized with BP or Fl. On the other hand, TEA indicated a negative effect for systems sensitized with α,α′‐azobisisobutylonitrile (AIBN), benzoyl peroxide (BPO), benzoin, and 2‐tert‐butylanthraquinone. Characteristics of the BP—and Fl—amine‐sensitized systems were compared with the systems sensitized with AIBN, BPO, and benzoin with respect to kinetics. Contrary to the latter polymerizations following the general kinetics, including the termination of growing chains by mutual deactivation, the former polymerizations were characterized by an elevated susceptibility of the primary radical termination.
Thioetherglycidyl resins. III. Products of condensation of bis(4‐mercaptophenyl)ether and bis(4‐mercaptophenyl)methane with epichlorohydrin
Authors: Charms Władysław
Published: April 2003

Thioetherglycidyl resins produced by condensation of bis(4‐mercaptophenyl)ether and bis(4‐mercaptophenyl) methane with epichlorohydrin were obtained by heterophase alkaline condensation. To define the optimal conditions of condensation, the following factors that influence the process were studied: the kind of organic phase and the mole ratios of epichlorohydrin:mercaptan, alcohol:mercaptan, and alkaline hydroxide:mercaptan. For all syntheses yield and the epoxide content were found. The structure of thioetherglycidyl resins with the highest epoxide content was determined by elementary analysis, infrared IR, and NMR spectra. The physical and chemical properties were also defined. The investigations covered the determination of some properties of resins, cured chemically or thermally with different curatives and thermal and mechanical properties of the cured compounds.
An alternate approach to the determination of rate parameters in copolymerization
Authors: Balaraman K. S. , Kulkarni B. D. , Mashelkar R. A.
Published: April 2003

A new method which proposes the use of a steady state CSTR is presented for the determination of rate parameters in a copolymerization system. The approach does not limit the conversion levels in the reactor and allows precise estimation of reactivity ratios. In the presence of gel effect, the suggested approach additionally reveals the cumulative variations of termination rate processes with extent of conversion. Such an a priori method which enables estimation of rate parameters in the high conversion region has not been available in the literature previously. The method proposed is illustrated using copolymerization of styrene–methyl methacrylate as a model system.
The transport phenomena of some model solutes through postcrosslinked poly(2‐hydroxyethyl methacrylate) membranes with different tactic precursors
Authors: Yoon Sung Chul , Jhon Mu Shik
Published: April 2003

Two series of membranes of various degree of hydration have been prepared by postcrosslinking highly syndiotactic and isotactic poly(2‐hydroxyethyl methacrylate) [P(HEMA)] with various amounts of hexamethylene diisocyanate (HMDIC). The equilibrium water content, the partition coefficient, and the permeability of the model solutes such as urea, acetamide, NaCl, 2‐propanol, and isobutanol for these membranes were measured. In addition, differential scanning calorimetry (DSC) study for the membranes was performed. The membranes of the isotactic precursor are more hydrated at 25°C compared to the ones of its syndiotactic counterpart. This may be due to the more hydrophobic nature of syndiotactic P(HEMA). The partition coefficient data show that the solutes of urea, acetamide, and NaCl are partitioned only into the water‐containing region, whereas the alcohol solutes are preferentially sorbed on to polymer matrix. The permselectivity data of urea to NaCl reveal that the permselectivity of crosslinked isotactic P(HEMA), (ISO) membranes increases as the amount of HMDIC is increased from 2.5 to 10 mol %, while the trend is reversed for crosslinked syndiotactic P(HEMA), (SYN) membranes. The apparent diffusivity order of urea, acetamide, and NaCl is not the same in those two characteristic membranes: the order is urea > NaCl > acetamide for highly crosslinked ISO membranes, and NaCl > urea > acetamide for all SYN membranes, which was compared with the free diffusion data in aqueous solution and interpreted in terms of the water‐structural orderlines within membranes.
Studies on synthetic‐polymer plates with high surface energy. IV. Determination of critical surface tension with aqueous solutions of salts
Authors: Kaneko Norio , Ohtsuka Yasuji
Published: April 2003

The critical surface tension (γc) of synthetic‐polymer plates with a functional group (amide, sulfonic, or carboxyl group) on their surface was determined by the Zisman plot using series of pure liquids (thiodiglycol, formamide, and water) and the aqueous solutions of the salts (NaCl, NaNO3, etc.) as a hydrogen‐bonding liquid. The Zisman plots gave a straight line, and the trends in the γc values coincide with those in the hydrophilicity anticipated from the θ values. The use of the aqueous salt solution coupled with the pure liquids as a hydrogen‐bonding liquid offers a practical determination procedure of the γc value for the materials with high surface energy.
Studies on suspension and emulsion. LIV. Shrinkage of polymer emulsion film having asymmetric porous structure
Authors: Okubo Masayoshi , Takeya Tetsuro , Tanaka Hitoshi , Matsumoto Tsunetaka
Published: April 2003

It was found that the film cast on a glass plate from emulsifier‐free ethyl acrylate–methyl methacrylate copolymer emulsion when separated from there shrank and curled immediately. This film had an “asymmetric” porous structure. It was discussed the relationship between the porous structure and the shrinkage due to the residual internal stress produced during film formation.
Tie chains and modulus of nylon 6 fibers
Authors: Mishra S. P. , Deopura B. L.
Published: April 2003

A large number of nylon 6 fiber samples with varying internal structure were obtained by changing draw ratios, drawing temperature, and quenching immediately after drawing. Modulus of these samples is analyzed by Takayanagi model and fraction of tie chains is obtained. It is observed that the modulus of these samples is directly proportional to the fraction of tie chains.
Controlled release of the herbicides 2,4‐D and dichlobenil from alginate gels
Authors: Connick William J.
Published: April 2003

The herbicides 2,4‐D[(2,4‐dichlorophenoxy)acetic acid] and dichlobenil (2,6‐dichlorobenzonitrile) were individually incorporated into 1.6–2.8‐mm alginate gel beads by using calcium chloride and barium chloride as gellants. The release rate of each herbicide from the beads into water was greatly influenced by drying and the choice of gellant cation. Slowest release was obtained with dried samples that were gelled with barium chloride. At the slowest rates, release of 2,4‐D was complete in 14 days, while only 59% of the less‐soluble dichlobenil was released in 150 days.
Thermal and photooxidation of polyolefins in the presence of 3,5‐ditertiarybutyl 4‐hydroxybenzyl thioglycollate, zinc diethyldithio carbamate, and irganox 1076
Authors: Kolawole E. G.
Published: April 2003

Three types of additives for polymers have been studied in polystyrene and poly(methyl methacylate). The effects of a novel thermal stabilizer 3,5‐ditertiarybutyl 4‐hydroxybenzyl thioglycollate (DBHBT), zinc diethyldithiocarbamate (ZnDEC) have been compared with the commercial antioxidant Irganox 1076. It has been found that the new antioxidant was far more superior to the commercial antioxidant. It also acts as a peroxide decomposer. It also gave considerable synergistic effects with ZnDEC both under thermal and photo degradations. Its use is being recommended instead of the present commercial ones.
Change of molecular aggregation state in amorphous region with uniaxial extension of preoriented polypropylene
Authors: Yamada K. , Takayanagi M.
Published: April 2003

Preoriented isotactic polypropylene was uniaxially drawn at various testing directions and testing temperatures. Change of the molecular aggregation state in amorphous region with extension was elucidated by measurements of melting temperature, enthalpy of fusion, and birefringence at each stage of extension. Melting temperature depends on both crystallite thickness and orientation function of amorphous chains. It is assumed that the enthalpy change of amorphous region takes place when oriented amorphous chains are transformed into random state by heating. The ratio of the enthalpy change of amorphous region in the sample after extension to that in the sample before extension monotonously increased with increasing orientation function of amorphous chains, fa, independent of testing direction and testing temperature. Increase of true stress with drawing led to increase of fa. Increase of fa with extension depended on the testing angle θ between the testing direction and the direction of the crystal c‐axis of the preoriented sample, and fa most remarkably increased in extension at θ = 45°.
Epoxy resins: Effect of extent of mixing on properties
Authors: Bell James P.
Published: April 2003

Inhomogeneities observed in cured epoxy resins by several workers appear to be related to the effectiveness of mixing the reactants. This mixing effectiveness also has an effect on the softening temperature Tg, of DETA cured resins, of as much as 10°C. Improved mixing of both DETA and Versamid 140 cured systems resulted in substantial ultimate strength improvement, in agreement with other recent results. Samples were mixed by hand, by a concentric cylinder mechanical mixer, and by application of an electrical filed between the cylinders of the mechanical mixer while mechanical mixing was in progress.
High‐density polyethylene filled with modified chalk
Authors: Badran B. M. , Gałȩski A. , Kryszewski M.
Published: April 2003

High‐density polyethylene was filled with chalk in various concentrations ranging from 10% to 60% by weight. Ethylene oxide oligomer Mw = 300 was used as a liquid modifier for chalk in the amount 0 ÷ 20 wt % of the filler. The mechanical properties of these composites showed that high density polyethylene filled with chalk have quite high ultimate elongation and impact strength while their elastic modulus and tensile strength are very near to those values for pure high density polyethylene. On the base of mechanical properties and microscopical observations, the crack and microcrack damping is attributed to the presence of ethylene oxide oligomer.
Photoinduced grafting of acrylamide onto polyethylene film by means of two‐step method
Authors: Ogiwara Yoshitaka , Takumi Masaru , Kubota Hitoshi
Published: April 2003

Benzophenone‐coated low‐density polyethylene (LDPE) was grafted with acrylic acid (AA), methacrylic acid (MA), acrylonitrile (AN), and methyl methacrylate (MMA) in an aqueous medium by photoirradiation. The first‐step graft samples thus prepared with a grafting of about 50% were subjected to second‐step photografting with acrylamide (AAm). On AA‐ and MA‐grafted LDPE samples, the second‐step grafting of AAm was very smooth, and a high level of grafting up to 800% was attained with ease. On the other hand, grafted LDPE samples employing hydrophobic monomers, AN and MMA, had a lower percent of grafting than those with hydrophilic monomers, AA and MA. By ESR study, a thermally stable radical was found in the first‐step graft sample irradiated with light of λ > 330 nm. Mechanisms for the formation of such a radical in the first‐step graft sample are proposed, and the contribution of the radical to the second‐step grafting is discussed.
Transient diffusion through multilaminate slabs separating finite and semiinfinite baths
Authors: Spencer H. G. , Chen T. C. , Barrie J. A.
Published: April 2003

Equations describing transient diffusion through multilaminate slabs with constant diffusion and partition coefficients for each lamina separating well‐stirred finite and semiinfinite baths are presented. Application is illustrated using a representative slab with three laminae.
Synthesis of rigid polyurethane foams from oligoester alcohols obtained from dimethyl terephthalate production wastes
Authors: Troev K. , Todoroy K. , Borisov G.
Published: April 2003

A study was conducted to synthesize oligoester alcohols from dimethyl terephthalate production wastes via transesterification with diethylene glycol and trimethylol propane. The oligoester alcohols obtained are suitable for preparing rigid polyurethane foams. The oligoester alcohols from trimethylol propane possess good physical and mechanical properties. The oxygen indices indicate that the polyurethane foams exhibit improved resistance to combustion due to the increased content of aromatic nuclei in the oligoester alcohols.
Plasma polymerization of tetrafluoroethylene in a field‐free zone
Authors: Buzzard Peter D. , Soong David S. , Bell Alexis T.
Published: April 2003

Plasma polymerization of tetrafluoroethylene by itself and mixed with inert gases has been studied in the field free zone inside a Faraday cage. The chemical structure was analyzed by ESCA, revealing both linear and branched products. Linear products are formed by less energetic plasmas and at low monomer residence times. Lower energy plasmas result from the use of lower powers and lower percentages of helium in the feed. Production of linear products under these conditions is probably due to lower rates of free radical and metastable formation in the plasma. Through a combination of kinetic and mass transfer effects, shorter monomer residence times under high flow rates and within short distances from the front edge of the electrode give rise to a lower concentration of free radicals at the electrode surface, producing a more linear polymer. Linear products were also formed at very high powers. This latter result is quite unexpected and is probably due to rapid gas phase polymerization. The chemical structure was not affected significantly by the substrate temperature or by hydrodynamics in this work. All of the evidence indicates that the gases were well mixed in the reaction zone for the range of process variables and for the gases studied. The deposition rate was also studied as a function of the reaction conditions. It was affected by the concentration of free radicals, the concentration of the monomer, and the substrate temperature. The observed deposition rate profile across the electrode is consistent with mass transfer and kinetic considerations governing free radical and monomer concentrations on the electrode surface. The deposition rate is greater at the lower substrate temperature used, probably due to enhanced adsorption process.
Gradient‐IPN‐modified hydrogel beads: Their synthesis by diffusion–polycondensation and function as controlled drug delivery agents
Authors: Mueller Karl F. , Heiber Sonia J.
Published: April 2003

Interpenetrating polymer network (IPN) membranes and gradient–IPN polymers were synthesized by immersing crosslinked, 2‐hydroxyethylmethacrylate copolymer beads which were swollen in polyol in solutions of diisocyanates. Diffusion of reactants and polycondensation take place simultaneously, and the polymer beads are modified by a polyurethane–IPN layer whose thickness and compositional gradient are a function of reaction rate and diffusion rate. When the reaction is fast relative to diffusion, the reaction zone is narrow and the IPN boundary layer is sharp, whereas when diffusion dominates, the reaction zone and the IPN‐modified region becomes broader and more diffuse. A water‐soluble drug imbibed into such gradient‐IPN‐modified hydrogel beads is released over a prolonged time period due to the less permeable IPN barrier and because of a drug‐distribution gradient in the polymer, which follows the polyurethane gradient. Diffusion polycondensation can be considered a special case of interfacial polycondensation, one in which the interface area is expanded into and stabilized by a preformed polymer matrix, which serves as reaction medium.
Shear modulus in closely packed gel suspensions
Authors: Taylor N. W. , Gordon S. H.
Published: April 2003

Rheological properties and swelling were examined in a series of concentrations of particles of crosslinked polyacrylate gels in water or salt solutions. The modulus during steady shear Gs = 2τ2/P11‐P22 was determined from shear stress τ and primary normal force difference P11‐P22 in a cone‐and‐plate rheometer. Gs was nearly constant with shear rate for the gel particles in the closely packed condition. The dynamic storage modulus G′ determined by ecentric rotating disc rheometry increased with increasing frequency for all concentrations. The apparent equilibrium shear modulus Ge determined by stress relaxation agreed closely at all concentrations and ionic strengths with the corresponding values of Gs, and hence Gs is considered a good estimate of equilibrium shear modulus for this gel material.
An analysis of the moisture‐related properties of hydrolyzed polyester
Authors: Sanders Erin Murphy , Zeronian S. Haig
Published: April 2003

Alkaline hydrolysis causes pitting of the surface of polyester (PET) fibers and films and improves their wettability, as indicated by contact angle measurements. The enhanced wettability is due to an increase in either the number or the accessibility of polymer hydrophilic groups to water and/or an increase in the roughness of sample surfaces. The increase of void space in the PET yarn and fabric structure, induced by treatment in aqueous NaOH together with the increased wettability of the fibers, was effective in improving the moisture transport properties of the materials. The NaOH‐treated PET fabrics transported the water further than isolated corresponding yarns, possibly because, in the fabrics, the spaces between the yarns acted as an additional reservoir that permitted further wicking to occur. It is apparent from immersion and equilibrium wicking capacity tests that a hydrophilic topical finish, as well as a change in the yarn/fabric structure and the hydrophilicity of their surfaces can increase the water holding capacity of PET fabric. The moisture regain and water retention values of the samples were determined, and it was found that such tests are not sufficiently sensitive to distinguish between the hydrophilicity of nontreated PET fabrics and that of PET fabrics modified either by application of a topical finish or by NaOH treatment.
The effect of addition of high‐density polyethylene on the crystallization and mechanical properties of polypropylene and glass‐fiber‐reinforced polypropylene
Authors: Gupta A. K. , Gupta V. B. , Peters R. H. , Harland W. G. , Berry J. P.
Published: April 2003

High‐density polyethylene up to about 30% by weight was melt‐mixed with polypropylene and short‐glass‐fiber‐reinforced polypropylene. The presence of high‐density polyethylene and glass fibers in the polypropylene matrix affects its crystallization characteristics, which were studied with the help of differential scanning calorimetry. The blend and composite samples have a large number of polypropylene domains apparently due to an abundance of surface nuclei; as a result, the tensile strength, tensile modulus, and toughness are enhanced. The temperature dependence of shear modulus and logarithmic decrement indicate that high‐density polyethylene can have plasticizing effect below the glass transition temperature of polypropylene. The scanning electron micrographs of fractured ends show the presence of dispersed domains in the composite samples.
Influence of tacticity on thermal degradation of PVC. V. Relation between the nature of labile conformations and the polyene distribution in the degraded polymer
Authors: Martinez G. , Mijangos C. , Millan J.
Published: April 2003

Four poly(vinyl chloride) (PVC) samples, 1, 2, 3, and 4, were prepared in bulk using 2,2′‐azodiisobutyronitrile at 90°C and 60°C and the same initiator together with UV irradiation at 0°C and −50°C, respectively. Fractions were obtained from samples 2,3, and 4 by extracting with acetone, sample 1 being completely soluble in this solvent. The whole PVC's as well as their acetone soluble and insoluble fractions, were characterized by determining the intrinsic viscosity, the osmometric molecular weight, and the tacticity; then they were thermally degraded up to conversion of 0.3% in powder state. The values of degradation rate for both the insoluble fractions and the whole PVC's were in agreement with some prior results on the influence of syndiotactic sequences on propagation step. The soluble fractions proved to be very unstable in comparison with the insoluble, which, despite the lower molecular weight of the former, seems to obey their higher content of isotactic conformations. The fine polyene distribution in the degraded polymers was carried out by UV–visible spectroscopy. The results reveal the occurrence of two different polyene distributions, and allow for the peculiar one of the soluble fractions to be related to polyenes consisting of two sequences of trans conjugated double bonds separated by a single cis double bond. The results clearly shows that there are two mechanisms for initiation of the PVC degradation, depending on whether it occurs by random unstable structures or by the normal GTTG isotactic or TTTG heterotactic triads. Moreover, these two initiation processes are proved to give rise to different types of polyenes, which accounts for the occurrence of two unlike mechanisms of propagation.
Longitudinal growth of polymer crystals from flowing solutions. X. Conditions for continuous growth on the rotor surface
Authors: Torfs J. C. M. , Smook J. , Pennings A. J.
Published: April 2003

Ultrahigh strength polyethylene fibers can be generated by stress‐induced crystallization from a supercooled solution subjected to Couette flow, usually referred to as the “surface‐growth” process. Under appropriate conditions, continuous fiber production can be realized for a period as long as 19 days, whereas under other circumstances a rapid interruption of the growth process is met. The present investigation deals with the origin of fiber fracture during “surface growth.” The limiting values of process variables required to maintain continuous growth have been established. Interruption of the continuous growth can occur in three different ways: (1) formation of a closed fiberloop around the rotor; (2) limited crystal growth rate; (3) rapid crystallization, leading to depletion of the gel on the rotor surface. The gel layer is being formed by adsorption of long molecules on to the rotor surface and subsequent “reptation,” resulting in a dense entanglement network of these molecules. These factors determine the boundaries of the triangularly shaped domain for continuous growth in a graph of the two main variables, namely the takeup speed and the rotor speed. Furthermore, it was noticed that the introduction of a wedge‐shaped groove in the surface of the Couette rotor leads to a substantial reduction of failure. Continuous growth could be established in the temperature range from 103–125°C when p‐xylene was used as a solvent. For p‐xylene solutions at a crystallization temperature of 110°C and using a teflon rotor of 115 mm diameter, a maximum takeup speed and rotor speed were 16 and 180 mm/s, respectively. Basically the restrictions of the process appeared to be due to the limited rate of crystallization and rate of adsorption of polyethylene molecules on the surface of the rotor.
Longitudinal growth of polymer crystals from flowing solutions. XI. The friction with the rotor surface
Authors: Torfs J. C. M. , Pennings A. J.
Published: April 2003

During the formation of ultrahigh modulus fibers by the “surface‐growth process,” the takeup stress is the main limiting factor lowering the attainable takeup speeds. This paper presents an investigation into the relative importance of the various factors contributing to takeup force and stress. Equations for force and stress have been derived which appear to agree with measurements. It has been concluded that the major part of the stress stems from the friction with the rotor surface and a smaller contribution arises from the coil deformation due to the flow. The equation for the stress has been employed to compute the maximum takeup speed.
Influence of the oxidizing temperature on the combustion of some well‐known polymeric materials
Authors: Breillat C. , Vantelon J. P.
Published: April 2003

The purpose of this work is to characterize the combustion of little samples of some well‐known polymeric materials, polyethylene, polypropylene, and polystyrene, in an atmosphere of quiescent hot air at different temperatures. The analytical treatment of this problem, which is a heat and mass transfer one with chemical reaction between pyrolysis and oxidizer gases, is based upon the fact that the burning regime is diffusion controlled. A mathematical approach developed from Spalding's theory, taking into account radiative effects, is applied to this model of combustion. Experimental results allow us to determine the apparent heat of combustion of these different materials and to study the evolution of radiative and convective fluxes.
Relationship between electron sensitivity and chemical structure of polymers as EB resists. I. Electron sensitivity of various polyamides
Authors: Ogata Naoya , Sanui Kohei , Azuma Chiaki , Tanaka Hozumi , Oguchi Kiyoshi , Nakada Tomihiro , Takahashi Yoichi
Published: April 2003

Polyamides containing double bonds or epoxy groups were synthesized and evaluated as electron beam (EB) resists, in order to find the relationship between electron beam sensitivity and chemical structure of the polyamides. It was found that polyamides containing double bonds, which have good solubility, are easily crosslinked by the electron beam exposure. The sensitivity of a polyamide with 70 mol% of the repeat units containing double bonds was equivalent to that of a 100% unsaturated polyamide which contained double bonds of 100% molar ratios, and thus it is not necessary that the polyamide be a homopolymer of unsaturated repeating units. The polyamides have good physical properties, and are adaptable to dry etching processes.
Mechanisms of rubber abrasion
Authors: Gent A. N. , Pulford C. T. R.
Published: April 2003

Rates of wear have been determined for several elastomer materials, using a razor‐blade abrading apparatus based on one described by Champ, Southern, and Thomas. Measurements have been carried out at different levels of frictional power input, corresponding to different severities of wear, at both ambient temperature and at 100°C, and both in air and in an inert atmosphere. It is concluded that wear occurs as a result of two processes: local mechanical rupture (tearing) and general decomposition of the molecular network to a low‐molecular‐weight material (smearing). Marked differences were shown by different elastomers. Carbon‐black‐filled natural rubber, SBR (styrene–butadiene copolymer) and EPR (ethylene–propylene copolymer) were particularly susceptible to decomposition and smearing, but for natural rubber and SBR the decomposition process was not observed in an inert atmosphere. It is attributed to molecular rupture under frictional forces followed by stabilization of the newly formed polymeric radicals by reaction with oxygen, if present, or with other polymer molecules, or with other macroradicals. Cis‐polybutadiene and trans‐polypentenamer did not appear to undergo smearing to a significant degree. The reactive radicals formed in these materials by molecular rupture are assumed to undergo rapid addition to other molecules so that the network structure is maintained. Rates of wear have been found to increase with the applied frictional force raised to a power n. The value of n was between 2.5 and 3.5 for unfilled materials at ambient temperature, in agreement with Champ, Southern, and Thomas, who pointed out a general correlation with mechanical fatigue. Filled materials were found to be less sensitive to the frictional force, whether wear took place by tearing or by smearing, having values of the index n of 1.5–1.8. Several observations suggest that wear, even in the absence of smearing, is not fully correlated with mechanical fatigue: the markedly lower wear rates for carbon‐black‐filled materials, the anomalous rankings of unfilled materials, and the relatively small effects of raising the test temperature to 100°C. It is concluded that abrasive wear by small‐scale tearing is not accounted for solely by the crack growth properties of the material but involves other failure processes as well.
Dehydrochlorinated poly(vinyl chloride)‐g‐polystyrene. II. Characterization and physical properties
Authors: Mukherjee A. K. , Gupta Achla
Published: April 2003

Dehydrochlorinated poly(vinyl chloride)‐g‐polystyrene (DHPVC‐g‐PSt) prepared by free radical grafting was characterized, and some of its physical properties were evaluated. The presence of graft was established by the appearance of new absorption peaks in the IR spectra of the graft copolymer. GPC analysis showed increase in the average molecular weights of the graft copolymer upon increase in the PSt content. Besides, GPC revealed the uniform PSt distribution of DHPVC‐g‐PSt. A marked improvement in the thermal stability of DHPVC‐g‐PSt over that of DHPVC and DHPVC/PSt blends was observed. Graft copolymers with high percent grafting were thermally more stable than even the original PVC. Stress–strain data indicated decrease in yield stress, breaking stress and elongation, along with an increase in the initial modulus, upon increase in PSt content of the graft copolymer.
Semi‐ and fully interpenetrating polymer networks based on polyurethane–polyacrylate systems. I. The polyurethane networks
Authors: Hourston D. J. , Zia Y.
Published: April 2003

The polyurethane networks based on commerical prepolymer, Adiprene L‐100, and trimethylol propane (system 1) and on toluene diisocyanate, polypropylene gylcol, and trimethylol propane (system 2) were prepared and characterized in a number of ways. The materials constitute the first formed networks in a series of interpenetrating polymer networks and semi‐interpenetrating polymer networks to be reported in subsequent papers in this series. System 1 networks were characterized by swelling tests which showed the Mc values to be sensitive to the amount of polyurethane present in the polymerization solvent. Stress–strain, stress–relaxation, and dynamic mechanical analyses wer also conducted. For system 2, Mc was measured, by both the swelling and the Mooney–Rivlin techniques, for materials in which the diol‐to‐triol ratios had been altered. the latter showed C1 increasing as Mc decreased while C2 was small and changed onlyy slightly indicating approximately ideal behavior. These Mc values were about 13 % larger than predicted by swelling.
Structure–property relationship in copolyesters. I. Preparation and characterization of ethylene terephthalate–hexamethylene terephthalate copolymers
Authors: Negi Yuvraj S. , Choudhary Veena , Varma Indra K. , Varma D. S.
Published: April 2003

Poly(ethylene terephthalate)‐containing ethylene and hexamethylene residues in the polymer backbone were prepared by melt condensation reaction of dimethyl terephthalate (DMT) and diffrent quantities of ethylene glycol (EG) and 1,6‐hexane diol (H) in the initial monomer feed. Several polyester samples were prepared by varying the mol % of 1,6‐hexane diol with respect to ethylene glycol in the initial monomer feed. These included 0.0 (PET), 2.5 (H1), 5.0 (H2), 7.5 (H3), 10.0 (H4), 12.5 (H5), 15.0 (H6), 17.5 (H7), 20.0 (H8), 50.0 (H9), 80.0 (H10), and 100.0 (H11), respectively. The polymers were characterized by recording IR spectra and intrinsic viscosity measurements. The relative thermal stability of the polymers was evaluated by dynamic thermogravimetry in air. An increase in mol % of 1,6‐hexane diol resulted in a decrease in melting points and thermal stability of copolymers. PET and copolyesters were spun to fibers by using the melt‐spinning technique. The fibers were drawn to draw ratios 2,3,4, and 5. In case of copolymes, tensile strength decreases slightly with increasing mol % of H whereas % elongation increases. The moisture regain and dye uptake in copolyesters was treatly enhanced as compared to PET.
Photoacoustic study of thermal degradation of polyurethane
Authors: Abu‐Zeid M. E. , Nofal E. E. , Abdul‐Rasoul F. A. , Marafi M. A. , Mahmoud G. S. , Ledwith A.
Published: April 2003

Polyurethane rigid foam shows substantial changes in its photoacoustic absorption spectra (PAS) on heating in the presence of air. These spectral changes are due to conjugated structures and quinone–imide formation, formed during degradation. The mechanism of degradation appears to be free radical in nature.
A comparison of physical and mechanical properties of polyimide films containing different metal ions
Authors: St. Clair A. K. , Taylor L. T.
Published: April 2003

Metal ions have been incorporated into linear polyimide films in order to improve the potential of these materials for applications in space. Various metals such as Al, Pd, Ag, Au, and Sn in a variety of chemical states were added to a polyamic acid prepared from 3,3′, 4,4′‐benzophenone tetracarboxylic acid dianhydride and 4,4′‐oxydianiline. Films of the metal ion‐filled polyamic acids were prepared and cured to the corresponding polymides by heating at 300°C in air. The cured films were characterized for such properties as glass transition temperature, electrical conductivity, and thermal stability. Modulii and tensile strengths of the metal‐containing polymide films were obtained at both ambient and elevated temperatures. Comparison of the physical and mechanical properties of these polyimide films as a function of metal additive is made.
The simulation of hydrolytic polymerization of ε‐caprolactam in various reactors: A simulation model for the tubular reactor with heat exchanger and its numerical solution
Authors: Tai Kazuo , Arai Yoshihiro , Tagawa Takashi
Published: April 2003

A concrete simulation model which deals with the hydrolytic polymerization of ε‐caprolactam (CL) in the tubular reactor (TR) with the heat exchangers (HEx's) was described, and a method for its numerical solution was presented. The numerical calculations were carried out for 13 cases, where the position and number of the HEx's in the TR were varied. The effects of the HEx on the distribution of the temperature in the TR and of the characteristic data of the polymerization (the concentration of CL and number average degree of polymerization) in the TR and at the outlet of the TR were investigated. The results suggested that the HEx positioned at the upper half of the TR and the HEx positioned at the lower half of the TR are effective to narrow the temperature distribution in the TR and to produce the polymer product with narrower molecular weight distribution, respectively.
Synthesis and thermal stability of carborane‐containing phosphazenes
Authors: Fewell L. L. , Basi R. J. , Parker J. A.
Published: April 2003

Carborane‐substituted polyphosphazenes were prepared by the thermal polymerization of phenyl‐carboranyl pentachlorocyclotriphosphazene. Successive isothermal vacuum pyrolyses were conducted on the polymer and examined for structural changes by infrared spectroscopy. The degradation products were ascertained by gas chromatography‐mass spectrometric analysis. It was found that the presence of the carborane group improves the thermal stability of the polymer by retarding the ring‐chain equilibrium processes of decomposition.
On the relationship between the thermal properties of modified polyurethane elastomers and the efficiency of antipyrens
Authors: Troev K. , Markova K. , Borisov G.
Published: April 2003

A study is made of the relationship between the thermal properties of polyrethane elastomers and the efficiencies of anitpyrens containing phosphorus and some containing both phosphorous and chlorine. It is shown that a ralationship exists between the thermal properties of polyurethane elastomers and the efficiencies of the antipyrens. It is also found that the presence of antipyrens in the molecules of the polyurethene elastomer effects the course of DTA, DTG, and TG curves. This permits antipyren efficiency to be qualitiatively evaluated as well as the antipyren optimal concentration to be determined.
Interrelation between moisture absorption, mechanical behavior, and extent of the boundary interphase in particulate composites
Authors: Theocaris P. S. , Papanicolaou G. C. , Kontou E. A.
Published: April 2003

The influence of moisture absorption on the extent of the boundary interphase in particulate composites is thoroughly studied. It was found that, during the process of moisture absorption there is a variation of the extent of the boundary interphase, closely related to the degradation of the mechanical behavior of the composite, as well as to the percentage amount of moisture absorbed. An explanation of the observed relationship was advanced, based on a theoretical mechanism of absorption. This study complements a previous one, where the observed degradation of the thermomechanical properties of particulate composites due to moisture absorption was shown to be intimately interrelated with the state and extent of the interphase between fillers and matrix.
Structure and formation of cellulosic chars
Authors: Sekiguchi Yuki , Frye James S. , Shafizadeh Fred
Published: April 2003

The formation and structure of chars produced on heating of cellulose, lignin, and wood have been investigated by FTIR and CP/MAS 13C‐NMR, and the results have been discussed in conjunction with parallel permanganate oxidation studies reported before. These data show that when cellulose is heated for 5 min within the temperature range of 325–350°C, the IR bands associated with hydroxyl and glycosidic groups in cellulose disappear, and new bands signal the formation of unsaturation and carbonyl groups by dehydration and rearrangement. The NMR data also show the disappearance of the glycosyl carbons at 60–110 ppm and the appearance of methyl and other paraffinic carbons at 0–60 ppm, aromatic carbons at 110–170 ppm, carboxyl carbons at 170–190 ppm, and carbonyl carbons at 190–220 ppm. On heating at 400°C the IR and NMR signals for the glycosyl groups completely disappear, the signals for carbonyl and carboxyl groups diminish, and those for the aromatic and paraffinic groups expand. At this stage the char contains about 69% aromatic and 27% paraffinic carbons. At the temperature range of 400–500°C the paraffinic carbon content is reduced to 12%, and a highly aromatic (88%) char is produced. This is consistent with the permanganate oxidation studies which show the production of polycyclic aromatic structures resulting from extensive condensation and crosslinking at these temperatures. The chars produced from wood and lignin at 400°C had about the same aromatic carbon content as the corresponding cellulose char; however, the char yields were higher due to the presence of the methoxy phenyl groups that survive the heating process, as indicated by strong NMR signals at 55 and 148 ppm.
Reactions of functional polymethacrylates grafted on phosphate‐modified calcium carbonate
Authors: Nakatsuka Takuo , Yamashita Shinzo
Published: April 2003

Five methacrylate monomers of methyl (MMA), dimethylaminoethyl (AEMA), 2‐chloroethyl (CEMA), 2,3‐epoxypropyl (GMA), and 2‐hydroxyethyl (HEMA) were graft‐polymerized in fine yields onto the calcium carbonate, which surface had been modified with 2,2′‐dimethyl‐2,2′‐azobisbutyronitrile‐4,4′‐dicarboxyethyl bisdihydrogenphosphate (AZDP). For the GMA and HEMA, styrene (St) was used as a hydrophobic comonomer for convenience to make homopolymers easily removed. The resulting grafted polymers were treated with such reagents: methyl iodide for the poly‐AEMA (pAEMA), sodium diethyldithiocarbamate (NaETC) for the poly‐CEMA (pCEMA), 2,2′‐iminodiethanol for the poly‐co‐GMA–St (pGMA–St), and m‐trifluoromethylphenyl isocyanate for the poly‐co‐HEMA–St (pHEMA–St). Diffusive reflectance infrared spectroscopy indicated that these reactions resulted in excellent yields, whereas the detection of the product from NaETC and 6‐chlorohexyl dihydrogenphosphate (CHP)‐modified calcium carbonate failed. The results of thermal analyses (DSC–TG), gel permeation chromatography (GPC), and changes of their surface wettabilities toward water are also discussed.
Glow discharge polymerization of tetramethylsilane by capacitive coupling of 20 kHz frequency and surface hardening of polyethylene sheet
Authors: Inagaki N. , Ohnishi Y. , Chen K. S.
Published: April 2003

Glow discharge polymerizations of tetramethylsilane (TMS) were performed by the capacitive coupling of a 20 kHz frequency in comparison with those by the inductive coupling of a 13.56 MHz frequency. The polymers prepared by the former coupling were poorer in carbon and hydrogen, but richer in silicon than those prepared by the latter coupling. These two polymers showing similar infrared spectra contained CH3, CH2, CH, SiOC, SiOSi, SiCH3, and SiCH2CH2Si groups. Some physical properties involving surface energy, thermal stability, and absorption spectra in the regions of the UV and visible light were determined. This coating procedure was applied for surface hardening of a polyethylene sheet. The surface hardness of the polyethylene sheet was enhanced by a coating of plasma films prepared from TMS or the TMS/O2 mixtures. Surface hardness was determined by the pencil method and hardness was enhanced from 2B to 2H. The adhesion between these plasma films and polyethylene sheet was good even when immersed in 0.9% NaCl solution at 40°C for 10 days.
Hybrid copolymerization of alkyl vinyl ethers with glycidyl ethers
Authors: Solaro R. , D'Antone S. , Orsini M. , Andruzzi F. , Chiellini E.
Published: April 2003

Homopolymerization and copolymerization experiments of isobutyl and dodecyl vinyl ether with propylene oxide, and some glycidyl ethers have been carried out by using both conventional cationic initiators (BF3, BF3·OEt2) and 4‐chlorophenyldiazonium tetrafluoborate as cationic photoinitiator. Conventional polymerization experiments performed under vacuum at low and room temperature gave rise to a mixture of the two homopolymers, indicating that the epoxide and vinyl ethers are incompatible with respect to chemical reactivity and that apparently no hybrid copolymerization occurs. Analogous results were obtained in parallel photoinitiated polymerization experiments.
Prediction of reverse osmosis performance of cellulose acetate membrane
Authors: Devmurari C. V. , Chandorikar M. V.
Published: April 2003

This study illustrates the analytical techniques involved in specifying the membrane and outlines the procedure for predicting the reverse osmosis (RO) performance of these membranes using feed solutions, containing either single solutes or mixed electrolytes having a common ion. The scientific basis for such specification and prediction techniques has been extensively discussed in the literature. In the present work, the governing transport equations for RO systems, involving preferential sorption of water at the membrane–solution interface, are utilized.
Refractive index increments of polyolefins
Authors: Horská Jitka , Stejskal Jaroslav , Kratochvíl Pavel
Published: April 2003

No Absrract.
Synthesis and properties of photosensitive rubbers. III. Synthesis of chloroacetylated polybutadiene and its photosensitivity
Authors: Azuma Chiaki , Hiramatsu Toshio , Tanaka Hozumi , Sanui Kohei , Ogata Naoya
Published: April 2003

Polymers having chloroacetate groups were prepared by addition reaction of various chloroacetic acids, such as mono‐, di‐, and trichloroacetic acids, to cis‐1,4‐polybutadiene under nitrogen atmosphere for obtaining photosensitive rubbers. The structure of products obtained was identified as a cyclized polybutadiene having pendent chloroacetate groups. The amount of the incorporated substituent increased up to the maximum of around 20 mol %, and the amount of the residual unsaturated groups in the polymer backbone decreased due to the cyclization of the double bond. Chloroacetylated polybutadiene had higher photocrosslinkability by UV irradiation than chloroacetylated polybutadiene had higher photocrosslinkability by UV irradiation than chloroacetylated chitosan or PVA owing to the high reactivity of the chloroacetate groups and the double bonds in the polymer. The photosensitivity depends both on the amount of the incorporated chloroacetate groups and the residual double bonds in the polymer and also depends on the glass transition temperature (Tg) of the polymer, and the dependence of the crosslinking reaction on Tg was interpreted to be due to diffusion controlled reaction between excited dichloroacetate groups and olefinic groups in the polymer.
Mixed gases separation by fine porous freeze‐dried cellulose acetate membrane
Authors: Tanioka A. , Ishikawa K. , Kakuta A. , Kuramoto M. , Ohno M.
Published: April 2003

A Freeze‐dried cellulose acetate membrane with high permeability and high separation factor was prepared. In the successive membrance process, the heat treatment temperature was 80°C for constant period of 10 min, acetone evaporation time was between 4 and 6 min, and the membrane was fixed during drying to prevent shrinkage. Gas permeabilities for such a membrane were inversely proportional to the square root of molecular weight, suggesting that the mechanism of gas flow through this membrane was Knudsen flow. Separation factors for H2He, ArKr, N2Kr, HeNe, H2Ne, HeAr, ArH2, HeKr, ArHe, and HeH2 were measured. These factors were higher than those of membranes reported already. Separation efficiency largely depended upon the combination of mixed gases. The combination of two atom molecules and one atom molecule lowered the separation efficiency compared with the combination of one atom molecule and one atom molecule.
Polymer/piezoelectric ceramic composites: Polystyrene and poly(methyl methacrylate) with PZT
Authors: Runt J. , Galgoci E. C.
Published: April 2003

Lead zirconate–titanate (PZT)/polymer composites have been prepared by in situ polymerization of styrene and methyl methacrylate around aligned, thin PZT rods. Hydrostatic piezoelectric coefficients (d̄h and ḡgh) measured by a dynamic technique yielded figures of merit (d̄hḡh) roughly four times that of homogeneous PZT for as‐polymerized composites. When these composites were annealed at a temperature slightly below the glass transition temperature of the matrix polymer and repoled, d̄hḡh increased nearly twofold due primarily to a reduction of the composite dielectric constant. The piezoelectric response was found to be essentially independent of frequency from 30 to 160 Hz.
Substituted 1‐[(phosphiny1)methyll‐2,4‐ and ‐2,6‐dinitrobenzenes, 1‐[(phosphinyl) methyl]‐2,4‐ and ‐2,6‐diaminobenzenes: New starting materials for preparation of fire‐resistant polymers
Authors: Mikroyannidis John A.
Published: April 2003

The nitration of the substituted [(phosphinyl)methyl]benzenes by fuming nitric and sulfuric acid gave the substituted l‐[(phosphinyl)methy1]‐2,4‐ and ‐2,6‐dinitrobenzenes (1). The formation of the two dinitro isomers was demonstrated by proton nuclear magnetic ('H‐NMR) and infrared (IR) spectroscopy. The nitration of [di(isopropoxy)phosphinylmethyl]benzene gave mainly the p‐nitro derivative due to steric hindrance. The phosphinyl ester groups of 1 were hydrolyzed by acids. The substituted l‐[(phosphinyl)methyl]‐2,4‐ and ‐2,6‐diaminobenzenes (2) were synthesized by catalytic hydrogenation of 1. In addition, the corresponding di(benzoy1amino) derivatives of 2 were prepared. Some of the synthesized compounds were investigated by gas chromatography‐mass spectroscopy (GC‐MS). Compounds 2 can be used as starting materials for preparation of phosphorus‐containing polymers such as polyamides, polyimides, polyureas, and bismaleimides and as curing agents for epoxy resins.