bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of catalyst on the curing of tetrafunctional epoxy resin formulations
Authors: Jagadeesh K. S. , Siddaramaiah
Published: April 2003

Cure kinetics of tetraglycidyl 4,4′‐diaminodiphenyl methane resin formulations with diaminodiphenylsulfone as hardener and borontrifluoride‐ethylamine adduct as accelerator has been studied by differential scanning calorimetry (DSC) technique both dynamically and isothermally. The DSC scans show multiple exotherm peaks, indicating the complex nature of reaction. The curing exotherms obtained have been analysed to derive the kinetic parameters associated with the curing process. The heat of reaction shows a decreasing trend with increasing catalyst concentration.
Polyamine‐modified urea‐formaldehyde resins. II. Resistance to stress induced by moisture cycling of solid wood joints and particleboard
Authors: Ebewele Robert O. , River Bryan H. , Myers George E. , Koutsky James A.
Published: April 2003

The objective of this study was to improve the durability and stability of urea‐formaldehydebonded wood products by decreasing the internal stress developed during resin cure and by improving the ability of the cured system to withstand cyclic stresses. Urea‐formaldehyde resins were modified by (i) incorporating urea‐terminated di‐ and trifunctional flexible amines into the resin structure, (ii) curing the resins with the hydrochloride derivatives of some of these amines (in place of ammonium chloride), or (iii) using both processes. The cyclic stress resistance of solid wood joints and the internal bond strength and thickness swell of particleboards made with these resins were compared with these properties in joints and particleboards made with an unmodified resin and a commercial urea‐formaldehyde resin. The strength of joints and the internal bond strength of particleboards made with resins modified with urea‐terminated hexamethylenediamine, bishexamethylenetriamine, and poly(propylene oxide) triamine at modifier contents of 13, 16, and 28 wt %, respectively, showed excellent stability even after repeated wet‐dry cycles. Similar stress resistance was shown by wood joints and particleboards bonded with the unmodified resin cured with the hydrochloride salts of hexamethylenediamine and triethyleneaminetriamine. In contrast, solid wood joints and particleboards bonded with the unmodified resin cured with ammonium chloride showed lower resistance to cyclic stress. Particleboards that possessed good cyclic stress resistance also showed less thickness swell.
Evaluation of the area under linear loss modulus‐temperature curves
Authors: Fay J. J. , Thomas D. A. , Sperling L. H.
Published: April 2003

The area under the linear loss modulus‐temperature curves, LA, has been shown to be related to the chemical composition of the material. In addition, it can be significantly affected by morphology in multicomponent polymer systems. To characterize LA quantitatively, base‐line corrections for instrumental contributions to LA were evaluated by several different methods and the results compared. In some instances, the calculation method affects only the LA magnitude, while general trends are unchanged; whereas in others, qualitative differences also become important. Not all of the methods described can be utilized universally. However, a straight‐line‐type of base line, similar to that which is used in infrared spectroscopy and differential scanning calorimetry, provides a widely applicable means of quantifying the loss area.
A polymeric amine–copper(II) complex as catalyst for the hydrolysis of 1,2,2‐trimethylpropyl methylphosphonofluoridate (soman) and bis (1‐methylethyl) phosphorofluoridate (DFP)
Authors: Hammond Philip S. , Forster Jeffry S.
Published: April 2003

The Cu (II) complex of poly‐4‐vinylpyridine, quaternized with 19 mol % ethyl bromide and 36 mol % 4‐chloromethyl‐4′‐methyl‐2,2′‐bipyridine, was examined as a catalyst for the hydrolysis of the toxic organophosphorous compounds bis (1‐methylethyl) phosphorofluoridate (1,

Registry no.: 1, 55‐91‐4; 2, 96‐64‐0.

DFP) and 1,2,2‐trimethylpropyl methylphosphonofluoridate (2, soman). Studies were carried out at 25.0 and 37.0°C for both substrates in MOPS buffer at pH 7.0. In the presence of 7.31 × 10−3 M catalyst at 25.0°C, soman is hydrolyzed with a first‐order rate constant of 0.019 min−1 (t1/2 = 37.5 min), whereas DFP hydrolyzes with a rate constant of 0.011 min−1 (t1/2 = 63.8 min). For soman, this represents a 14‐fold increase over the uncatalyzed rate in the same buffer. Other studies examined the effect of a strongly sorptive polymeric resin on catalysis by this copper‐containing polymer and found a dramatic decrease in the hydrolysis rate of soman in the presence of the polymeric sorbent.
Effect of crosslinking agents on the structure and properties of polyurethane millable elastomer composites
Authors: Paulmer R. D. A. , Shah C. S. , Patni M. J. , Pandya M. V.
Published: April 2003

A study of the effect of crosslinking agents on the structure and properties of the millable polyurethane (PU) elastomer is reported here. Effects of the conventionally used dicumyl peroxide (DCP) and tolylene disocyanate dimer (TDID) on the curing characteristics, mechanical properties, and relative thermal stabilities of the PU composites have been compared. Use of X‐ray diffraction as a supportive evidence helps in understanding the nature of crosslinking. The mixture of DCP and TDID is also evaluated as crosslinking agents. A dramatic improvement in the mechanical properties and thermal stability is observed because of the mixed type of crosslinking obtained by the combined use of DCP and TDID. Effect of carbon black loading shows an increase in the mechanical strength with a decrease in the elongation. The results obtained from various properties measurements have been satisfactorily explained with a general model of crosslinking.
The thermal aging of filled polyurethane
Authors: Trong‐Ming Don , Chiu Wen‐Yen , Hsieh Kuo‐Huang
Published: April 2003

Thermal aging and strain endurance experiments on a filled rubber were performed at several temperatures. The rubber was polyurethane (PU) made from hydroxyl‐terminated polybutadiene (HTPB) with 4,4′‐diphenyl methane disocyanate (MDI). The filler was sodium chloride. The mechanical properties, glass transition temperature, dynamic viscoelasticity, and chemical structures were investigated for filled and unfilled PU under an aging period at 60 and 80°C and 50% relative humidity. We found that at 60°C the chemical structures of the filled and unfilled rubbers had no changes in 30 days during aging. But moisture had some effects on the filled PU and changed its mechanical properties. At 80°C, the chemical structures of the filled and unfilled PU had changed due to the thermal oxidation of polybutadiene in aging. The deterioration was more apparent for the filled rubber than for the unfilled. The prestraining would dewet the filler from the samples and it increased the voids.
Swelling of poly(glycidyl methacrylate) gel particles by organic solvents
Authors: Fukuda Takeshi , Kohara Noriyuki , Onogi Yoshihiko , Inagaki Hiroshi
Published: April 2003

Fine particles of poly(glycidyl methacrylate) (PGMA) were prepared by suspension polymerization and crosslinked via the ring‐opening reaction of the epoxide group with formic acid. A fraction of the spherical gel particles averaging about 70°m in diameter was examined under an optical microscope with its swelling behavior in a number of solvents. Equilibrium degrees of swelling were established with accuracy to show that this polymer gel has rather unusual affinities for solvents: (i) It is swollen (and, without the crosslinks, soluble in most cases) in many types of solvents, (ii) it cannot be represented by a single value of solubility parameter, and (iii) it is not swollen at all in water nor in aliphatic alcohols, in spite of the presence of hydroxy groups in the chain.
Castor oil based UV‐curable polyurethane‐acrylate interpenetrating networks
Authors: Homan James G. , Yu Xue‐Hai , Connor Timothy J. , Cooper Stuart L.
Published: April 2003

Castor oil was reacted in varying ratios with β‐isocyanatoethyl methacrylate to form a liquid urethane–methacrylate prepolymer. This prepolymer was then cured using ultraviolet radiation to form a series of base polymer networks or using various methacrylates to form conetworks. By swelling the base networks with the appropriate methacrylate monomers, semi‐ and full interpenetrating networks (IPNs) were prepared with similar compositions. All of the materials formed transparent films. Results of swelling experiments, dynamic mechanical analysis, differential scanning calorimetry, and small angle x‐ray scattering are discussed.
Accelerated failure of bisphenol‐A polysulfone during electron beam irradiation under an applied stress
Authors: Hill David J. T. , Lewis David A. , O'Donnell James H.
Published: April 2003

Bisphenol‐A polysulfone, poly(oxy‐1,4‐phenylenesulfonyl‐1,4‐phenyleneoxy‐1, 4‐phenyleneisopropylidene‐1,4‐phenylene), PSF (I) showed greatly reduced resistance to electron beam irradiation when subjected simultaneously to an applied tensile stress. The creep rate increased, and the time (dose) to failure of the sample decreased with increasing stress. The failure strain was constant for different applied stresses. Air, oxygen, and moisture caused decreases in radiation resistance compared with a dry nitrogen atmosphere. Increasing the irradiation temperature from 0 to 90°C resulted in substantially decreased radiation resistance.
Study on modified phenolic resin. II. Modification with p‐hydroxyphenylmaleimide/styrene copolymer
Authors: Matsumoto A. , Hasegawa K. , Fukuda A. , Otsuki K.
Published: April 2003

The improvement of heat resistance and mechanical properties of phenolic resin was examined with the blend of novolac and copolymers prepared from p‐hydroxyphenylmaleimide (HPMI) and styrene.

Copolymers of HPMI and styrene with various molecular weights were synthesized. Glass transition (Tg) and thermal decomposition temperatures of the copolymers were measured by differential scanning calorimetry (DSC) and thermogravimetry (TG), respectively. The miscibility of the copolymers with novolac was examined by DSC.

It was found that the copolymers had a good heat resistance and a good miscibility with novolac. Molding compounds were prepared by hot roll‐kneading of mixtures that involved novolac, copolymer, hexamethylenetetramine (hexamine), and glass fiber. It was found that the test pieces prepared by transfer molding from the molding compounds showed a good heat resistance and better mechanical properties than phenolic resin modified with HPMI homopolymer.
Enhanced enzymolysis of never‐dried cotton fibers belonging to different species
Authors: Bhatawdekar Shaila P. , Sreenivasan S. , Balasubramanya R. H. , Sundaram V.
Published: April 2003

Enzymolysis of cotton cellulose in their never‐dried state, belonging to all the four cultivated species of cotton, was carried out with the enzyme derived from penicillium funiculosum F4. Hydrolysis to reducing sugars was almost complete for all the cottons in 6 h, though glucose percentage varied. X‐ray characterizations of the residues obtained, which were both after enzyme and acid hydrolysis, showed significant differences between both hydrolyses, as well as differences in the behavior of different cotton fibers towards enzyme action. These differences have been attributed to the different structural organization of cellulose in the secondary cell wall of cotton fibers.
Fabrication methods for latex‐based elastomer composites reinforced with long discontinuous fibers
Authors: Epstein Mikael , Shishoo R. L.
Published: April 2003

Rubber‐ or elastomer‐based composites have so far been reinforced with randomly dispersed staple fibers of very short lengths. In this work, methods have been devised to produce composites where the dispersed fibers have considerably greater lengths. This achievement was possible by applying the rubber or elastomer as latex when mixing it with the fibers. As compared with earlier processes, the viscosity is considerably lower, thus permitting easier mixing so that longer staple fibers can readily be used.
Some observations on morphology of anhydride‐modified polystyrene
Authors: Chatterjee S. , Biswas M.
Published: April 2003

Friedel–Crafts acylation reaction between polystyrene and phthalic anhydride in the presence of AlCl3 has been performed in two different solvents, 1,2‐dichloro ethane and nitro‐benzene. The morphology of the condensate prepared in 1,2‐dichloroethane has revealed the participation of 1,2‐dichloroethane, i.e., a competitive Friedel–Crafts alkylation reaction.
Structure–property relationships for styrene crosslinked polyesters. II. Glass transition temperature
Authors: Bellenger V. , Mortaigne B. , Verdu J.
Published: April 2003

The glass transition temperature of 10 styrene‐free polyester prepolymers and the corresponding networks crosslinked by about 40% by weight of styrene were determined by DSC (and by DMA in the case of networks).

The glass transition temperature TgL of an hypothetical copolymer containing all the difunctional units of the network was then calculated. It is an increasing function of the molar weight of the prepolymer and of the phthalate/maleate molar ratio. From IR and NMR measurements, it was established that the structural irregularities other than polyester chain ends, especially unreacted double bonds, can be neglected to a first approximation. A constituent repeat unit (CRU) defined on the basis of these results allows the calculation of the crosslink density n. Then, various theories of the effect of n on Tg are compared. It appears that neither the Fox and Loshaek nor the Di Marzio approach gives good results. The crosslinking constants are lower than those found for aliphatic skeleton polyesters or epoxies. In the series under study, they display a tendency to decrease with the aromatic content. Some possible reasons of this peculiar behavior are discussed.
Functional polymers for colloidal applications. II. Hydrophobic effects of polyacrylic copolymer on dispersing polar and nonpolar particles
Authors: Kuo Ping‐Lin , Chang Ta‐Cheng
Published: April 2003

The polyacrylic acids with fixed molecular weights are specifically esterified by lauryl alcohol and methyl alcohol to prepare copolymers. These copolymers are used as dispersants for dispersing TiO2 and carbon black. It was found that lauryl‐esterified copolymers decrease the minimum viscosity and optimum concentrations both for TiO2 and carbon black due to strong hydrophobic interactions. However, the methyl esterified polyacrylic acid significantly broadens the range of optimum concentrations due to the interruption of polymer interactions between particles by methyl groups. Four different dispersion systems (LB/carbon black, LB/TiO2, MB/carbon black, and MB/TiO2) are used. These results are discussed and correlated to the structure of dispersant. The bridging effect of esterified lauryl group and the antibridging effect of esterified methyl group are used tó interpre the viscosity phenoma of those dispered systems.
Plasma polymerization of organoisothiocyanates. II. Structure of polymer film
Authors: Czeremuszkin G. , Wróbel A. M. , Kryszewski M.
Published: April 2003

Methyl‐, n‐propyl‐, allyl‐, and phenyl isothiocyanates (MITC, PITC, AITC, and PHITC respectively) were polymerized in an RF (13.56 MHz) plasma electrodeless flow system. The plasma produced polymers were characterized using IR, GPC, GC/MS, and direct pyrolysis mass spectrometry (DPMS) techniques. The solubility tests and chromatographic examinations of the polymers revealed a small soluble fraction which contained a mixture of oligomers with a predominance of dimers and trimers. Molecular structure of the components of these fractions, identified by GC/MS, suggests fragmentation of the monomers to reactive fragments: \documentclass{article}\pagestyle{empty}\begin{document}$$ ^ \cdot {\rm RSCN},^ \cdot {\rm RCN},{\rm R}^ \cdot ,^ \cdot {\rm CN} $$\end{document} (in the case of MITC, PITC, AITC) and \documentclass{article}\pagestyle{empty}\begin{document}$ ^ \cdot {\rm ArNCS},{\rm PhS}^ \cdot ,{\rm Ph}^ \cdot ,^ \cdot {\rm CN} $\end{document} (in the case of PHITC). The DPMS data, being generally consistent with IR and GS/MS results, proved the presence in the polymers of sulfide, polysulfide, thiocarbonyl (–CS–S–and–S–CS–S–) groups, and molecular sulfur S8. Elementary plasma reactions involved in the formation of the observed structural units are proposed.
The enhancement of microvoids in acrylic fibers
Authors: Qin Jian
Published: April 2003

The present work is concerned with the spinning of two series of blend fibers containing acrylic copolymer(PAC) and small amount of secondary polymer, such as polyvinyl acetate (PVAc), polystyrene (PS), acrylonitrile‐styrene (AS) and acrylonitrile‐vinyl acetate (AVAc) copolymers. The blend acrylic fibers we developed have a microporous structure that renders them highly water retentive and confers several other excellent properties. Some factors were further studied that greatly influence the microporous volume and micropore size distribution, such as compatibility and phase separation of the polymer blends, the composition and sequence distribution of the secondary copolymers, and fiber formation conditions.
Melt viscosity and flow birefringence of polycarbonate
Authors: Nagai Tohru , Kimizuka Yuichi , Nito Keiichi , Seto Jun'Etsu
Published: April 2003

Melt viscosity and flow birefringence of bisphenol A‐type polycarbonate were measured and analyzed by the application of rubber‐like photoelastic theory. The melt viscosity in the Newtonian flow region increased with the molecular weight to the power of 3.4. In polycarbonate, the shear stress of the Newtonian flow region was to 106 dyn/cm2, whereas in PMMA it was at most 3 = 105 dyn/cm2.

The flow birefringence δn has a linear relation with shear stress S, that is δn = 5.7 × 10−10 S. The principal polarization difference of flow unit α1 – α2 was 1.62 × 10−23 cm3, which was obtained by the application of the rubber‐like elastic theory. In PMMA, it was 3.9 = 10−25 cm3; about 1/40 of that was polycarbonate. The anisotropy of polarizability of the flow unit of polycarbonate was also about 40 times larger than that of PMMA. So the anisotropy reflected the large flow birefringence of the polycarbonate.
Triazine networks modified with monofunctional reactive cyanate ester monomers
Authors: Papathomas K. I. , Wang D. W.
Published: April 2003

The preparation of cyanate ester thermosetting resins by coreacting a fluorinated bisphenol A dicyanate (6F‐BADCY) monomer with a monofunctional reactive cyanate, namely, the dinonyl phenol cyanate (DNPC), is described in this paper. Our objective in this study was to modify the 6F‐BADCY system with reactive diluents of a nonpolar nature and produce matrix resins processable at FR‐4 epoxylike conditions. By introducing the monofunctional cyanate as a reactive diluent, it is expected that the molar crosslink density of the resulting network will be reduced. Highly branched triazine polymers will result from this approach. Dinonyl phenol cyanate was quantitatively synthesized by reacting dinonyl phenol with cyanogen bromide in the presence of triethylamine.
Butadiene–styrene copolymerization initiated by n‐BuLi/THF/t‐AmOK
Authors: Lehong Bu , Shengkang Ying
Published: April 2003

In this article, the anionic copolymerization of butadiene and styrene initiated by n‐BuLi/THF/t‐AmOK in cyclohexane at 50°C has been studied in detail. The various ratios of the modifier (THF and t‐AmOK) to the initiator (n‐BuLi) influence the copolymerization rate and composition of copolymers.

It has been shown that this polymerization system is a complex one in which there exist multiple active species. By adjusting the ratio of K to Li and the ratio of THF to Li, copolymers with compositions almost identical to the ratio of initial monomers at different stages of conversion have been obtained.

The propagating regularity of various active species has been discussed qualitatively.
The microstructure of butadiene and styrene copolymers synthesized with n‐BuLi/THF/t‐AmOK
Authors: Lehong Bu , Shengkang Ying
Published: April 2003

A study of the microstructure of copolymers, synthesized by B–S anionic copolymerization, initiated with n‐BuLi/THF/t‐AmOK in cyclohexane at 50°C, has been performed. Moreover, the mean sequence length in the B–S copolymer chain has been determined. The result showed that the microstructure of copolymers were sharply influenced by various ratios of modifier (THF, t‐AmOK) to initiator (n‐BuLi). By selecting a proper ratio of K/Li and THF/Li, B–S copolymers with unique randomness, having composition almost indentical to the initial monomer ratio at different stages of conversion and very low vinyl content, have been obtained.

The formation mechanism of the copolymer chain structure is discussed.
Analytical characterization of weather‐degraded polyacrylonitrile fiber
Authors: Howell Huston E. , Patil Arvind S.
Published: April 2003

Polyacrylonitrile (PAN) fiber was analytically characterized to identify the structural changes that occur due to atmospheric degradation. Degradation structures comprised of CC, CN, and CO species were identified using infrared spectroscopy. A significant decrease in the molecular weight was measured using size exclusion chromatography. PAN–acrylate copolymer fibers were analyzed and found to exhibit the same type of structures and changes in properties upon atmospheric degradation.
Infrared spectra of jute stick treated with white‐rot fungus
Authors: Roy A. K. , Bag S. C. , Basak M. K. , Sen S. K.
Published: April 2003

Jute stick was treated with white‐rot fungus for incubation periods of 6 days (MBA) and 12 days (MBB). The infrared spectra of fungus treated samples (MBA and MBB) and control jute stick (MBC) were analyzed and compared. The bands attributed mainly to hemicellulose show an increase in absorbance intensity ratios (Aν/A2900) with increase of incubation time. Similarly the bands attributed to lignin show an increase in the absorbance intensity ratios with increase of incubation time. Increase in the intensity of 1635 cm−1 band with increase of incubation time was also observed.
Determination of the fiber content in polymer composites by means of X‐ray absorption measurements
Authors: Schipp C. , Röber S. , Zachamann H. G. , Seferis J. C.
Published: April 2003

The X‐ray absorption coefficients of carbon fibers, different polymeric matrix materials, and composites were measured and the fiber contents in the composites were calculated from the measured absorption. In addition the fiber content determinations were performed by means of acid digestion of the polymeric matrix and weighing. Good agreement was found between the results obtained by the two different methods. The experimental error in the fiber content measurements was determined as a function of the difference in the coefficient of the matrix material and the fiber.
Polyester adhesion to chromium‐coated steel for poly(ethylene terepthalate) and an isophthalate copolymer
Authors: Yokoya Hirokazu , Porter Roger S.
Published: April 2003

The performance of PET [poly(ethylene terephthalate)] and a copolymer of PET has been tested as an adhesive for chromium‐coated steel. Crystallinity in the polyesters is found to limit adhesion, probably by restricting chain mobility. Lamination temperatures above the melting point of each polyester give the best adhesion. Degradation of the polyesters at yet higher temperature resulted in both reduced polymer cohesion and adhesion.

Optimum bonding to steel was obtained at lamination temperatures between 230 and 275°C for the copolyester and between 280 and 300°C for PET. The standard laminate compression time was 15 min at 50 kg/cm2. Adhesion was evaluated by the ASTM T‐peel test. Assessments were made by both the peel energy and the peak load for peel.
Maleation of linear low‐density polyethylene by reactive processing
Authors: Gaylord Norman G. , Mehta Rajendra , Mohan Doraiswamy R. , Kumar Vijay
Published: April 2003

The reaction of maleic anhydride (MAH) with molten 2 MI poly(ethylene‐co‐butene‐1) (LLDPE) at 160°C in the presence of peroxyesters (t1/2 < 10 s) as catalysts resulted in the formation of a mixture of cross‐linked and trichlorobenzene‐soluble LLDPE‐g‐MAH. The soluble fraction constituted more than 50% of the mixture and had an MI of 0.0 and an MAH content ranging from 0.3 to 1.8 wt %. The presence of tri(nonylphenyl) phosphite (TNPP) in the LLDPE–MAH–t‐butyl peroctoate (tBPO) reaction at 160°C increased the MI of the soluble product to 0.7–2. The amount of soluble polymer increased at higher TNPP concentrations while its MAH content ranged from 0.05 to 0.54 wt %, with most contents in the 0.2–0.3 wt % range. The color development that usually occurs in polyolefin–MAH reactions was reduced by the presence of TNPP. However, the reaction of TNPP with the peroxide and from the thermal decomposition thereof reduced the availability of the excited species necessary for the appendage of MAH units onto the polyofin.
Transport properties of dichloromethane in glassy polymers. I. Atactic polystyrene films
Authors: Vittoria V. , Filho A. Ruvolo
Published: April 2003

Sorption and diffusion of dichloromethane vapor were measured in atactic polystyrene films, obtained with different cooling conditions and after controlled aging times at different temperatures. The diffusional behavior is characterized by three zones, depending on temperature and penetrant activity. In Zone I, at low activity, the diffusion coefficient is independent of vapor concentration; Zone II is characterized by concentration‐dependent diffusion, whereas in Zone III structural transformations are possible. The study of diffusion at three temperatures allowed building of a temperature‐penetrant concentration diagram, which is very useful to visualize the different zones of behavior. The aging at room temperature has no effect on the curve of sorption as a function of vapor activity, whereas it determines two effects on the diffusion: a decrease of the zero concentration diffusion coefficient and a more and more anomalous behavior with the aging time. The aging at 70°C produces the same effects on the diffusion behavior as the aging at room temperature; in addition, a decrease sorption is observed at low penetrant activity. The possible presence of ordered domains, impermeable to the vapor, in the samples stored at 70°C, was suggested on the basis of sorption results.
Extruded blends of a thermotropic liquid crystalline polymer with polyethylene terephthalate, polypropylene, and polyphenylene sulfide
Authors: Heino Markku T. , Seppälä Jukka V.
Published: April 2003

Structure–property relationships were investigated for blends of a polyester‐type thermotropic liquid crystalline polymer (LCP) with polyethylene terephthalate (PET), polypropylene (PP), and polyphenylene sulfide (PPS). The polymers were melt blended in a twin‐screw extruder and the blends were extruded to strands of different draw ratios. Tensile properties of the blends were determined as a function of LCP content and draw ratio and compared with the results of morphological and rheological analyses. In general, the strength and stiffness of the matrix polymers were improved with increasing LCP content and draw ratio. At a draw ratio of 11, the blends of PET/30 wt % LCP exhibited a tensile strength about three times and an elastic modulus nearly four times that of pure PET. All blends exhibited a skin/core morphology with thin fibrils in the skin region. The formation and the sizes of the fibril‐like LCP domains in the matrices were found to depend on LCP content and the viscosity ratio of the blend components.
Structural changes in draw‐textured poly(ethylene terephthalate) filaments during heat‐setting
Authors: Bechev C. D. , Mishinev J. T.
Published: April 2003

A sample of high‐elastic‐textured poly(ethylene terephthalate) (PET) yarns were subjected to different conditions of heat‐setting, i.e., different temperatures and overfeeds. The structural changes were characterized by different physical methods. The orientation factors of crystalline and amorphous regions were calculated. The yarn tensions acting during the SET process were measured and corrected to the structural data. The results obtained show that two processes take place during the SET process: relaxation of the molecule segments in amorphous regions and change of crystallite orientation in microfibrils. A simple model for explanation of the structural changes in simultaneously draw‐textured PET yarns is proposed.
On the graft polymerization of styrene and acrylonitrile onto polybutadiene in the presence of vinyl acetate. II. Properties of graft polymers
Authors: Schellenberg Jürgen , Hamann Bernd
Published: April 2003

The properties of the graft polymers of styrene, acrylonitrile, and vinyl acetate onto polybutadiene rubber that were prepared for the modification of graft polymers of styrene and acrylonitrile onto polybutadiene (ABS polymers) by emulsion polymerization up to a high degree of conversion have been studied and discussed. Both the impact strength and notched impact strength of the graft polymers have been found to remarkably increase with a rising quantity of vinyl acetate, in particular, in the case of styrene substitution, whereas in the case of acrylonitrile substitution by vinyl acetate, the two characteristics become noticeably poorer. The effects of the vinyl acetate amount and the type of substituted monomers on bending strength, tensile strength, Vicat softening point, and glass transition temperature of the graft polymers are also clearly different. Furthermore, the properties of the above graft polymers blended with styrene/acrylonitrile copolymers have been studied.
Triallylphosphine plasma polymerization and reaction of the product with volatile transition metal compounds
Authors: Clymer S. D. , Morosoff N. C. , Crumbliss A. L.
Published: April 2003

The plasma polymerization of triallylphosphine in order to form a crosslinked polymer thin film is described. The plasma polymer thin film has been characterized and shown to contain a high proporation of CC and P groups conserved from the monomer. The accessibilty of the phosphine groups has been demonstrated by reaction with O2, NO, Ni(CO)4, and Fe(CO)5. Reaction with O2, and NO results in a PO moiety formation. Reaction with the gaseous metal carbonyls results in fixation of the metal via complexation by the P groups as a result of exchange with CO ligand(s). This illustrates the utility of a ligand donor group containing plasma polymer as an avenue for the formation of a single phase transition metal containing plasma polymer.
Correlations involving modulae and cross‐polarization time constants for a series of polyurethane elastomers
Authors: Marcinko J. J. , Parker A. A. , Shieh Y. T. , Ritchey W. M.
Published: April 2003

Correlations between the macroscopic bulk polymer properties storage modulus (E′) and loss modulus (E″) and the microscopic property of cross‐polarization as represented by the time constant TCH have been established for a series of polyurethane elastomers. The dependence of E′, E″, and TCH as a function of molecular weight, rigid domain concentration, and temperature are graphically presented as a series of log plots. An experimental relationship is presented that shows that the distribution of motions of the flexible domains appears to be the major factor in the success of these correlations.
Synthesis and properties of an easy‐processable bismaleimide thermoset resin
Authors: Winter H. , Mostert H. A. M. , Tholen M. G. W.
Published: April 2003

Reaction of methylenedianiline and maleic anhydride in acetone, followed by cyclodehydration in the presence of acetic anhydride and 1,4‐diazabicyclo [2.2.2] octane as a catalyst, affords a mixture of compounds, Desbimid, with maleimide, isomaleimide, and acetamide groups. Dissolution of this mixture in styrene and 2‐hydroxyethyl methacrylate results in clear liquid resins. The viscosity of the formulated resins ranges from 100–1700 mPas at 25°C depending on the concentration of Desbimid. These systems can be processed and cured at ambient temperatures until demoulding and postcured at temperatures up to 200 or 250°C. The flexural modulus, flexural strength, and elongation at break of a number of cured formulations are found between 3500–3800 N/mm2, 90–115 N/mm2, and 2.7–3.5%, respectively.
Preparation of epoxy‐terminated poly(aryl ether sulfone)s and their use as modifiers for epoxy resins
Authors: Iijima T. , Hiraoka H. , Tomoi M.
Published: April 2003

Epoxy‐terminated poly(aryl ether sulfone)s (PSE) were prepared by the reaction of epichlorohydrin with hydroxyethyl‐terminated polysulfones, which were synthesized from chloro‐terminated polysulfones (PSC) and diethanolamine. Both PSE and PSC were used as modifiers for toughening of bisphenol A diglycidyl ether epoxy resin cured with p,p′‐diaminodiphenyl sulfone. The mechanical, thermal, and dynamic viscoelastic properties of the modified resins were examined and compared to the parent epoxy resin. The effectiveness of PSC was larger than that of PSE. The fracture toughness, KIC, for the modified resin increased 45% at slight expense of its mechanical properties on 20 wt % addition of PSC (Mw 5300). These results were discussed in terms of the morphological and dynamic viscoelastic behaviors of the modified epoxy resin system.
Synthesis of highly conducting nylon‐6 composites and their electrical properties
Authors: Park Yun Heum , Choi Sang Hoon , Song Suk Kyu , Miyata Seijo
Published: April 2003

Highly conducting nylon‐6 composites are synthesized by exposing nylon‐6 films or fabrics impregnated with an oxidizing agent, cupric chloride, simultaneously to aniline and hydrochloric acid vapors. The conductivity of composite films reaches up to 10−2 S/cm and can be controlled by varying the experimental conditions for the composite synthesis. The effects of the concentration of cupric chloride, exposure time to aniline and hydrochloric acid vapors, and concentration of hydrochloric acid to the polyaniline content and the conductivity of nylon‐6/polyaniline composites are analyzed by means of statistical F test. The morphology change of composite films resulting from the synthesis conditions, conductivity in relation to the morphology, and stability of conductivity to ambient air exposure have been investigated.
Prediction of vibration damping properties of polymer‐laminated steel sheet using time–temperature superposition principle
Authors: Liao Fu‐Sen , Hsu Tzu‐Chien J.
Published: April 2003

The vibration damping properties of the polymer‐laminated steel sheet have been investigated theoretically and experimentally. The laminate consisted of a polymer layer, which was sandwiched between two steel sheets. Two polymers a polyvinyl butyral and a copolymer of ethylene and acrylic acid, were used. The theoretical analysis was based on a model proposed by Ungar. A frequency analyzer was used to measure the loss factor of the laminate. The model required rheological data, such as storage modulus G′ and loss tangent of the polymer at high frequency, which could not be obtained from commercially available dynamic rheometers. The time–temperature superposition principle was applied to the laminated polymer to construct the master curves of G′ and loss tangent vs. frequency. These master curves provided rheological data at high frequency, which were superposed from data measured at low temperature. The results showed that a discrepancy existed between the loss factors predicted with superposed and without superposed data and the reasons for this discrepancy were discussed. The measured loss factors of the laminates at high frequency followed the predictions using superposed data, but not for those measured at low frequency. Factors accounting for this deviation were analyzed. The results also indicated that, in general, the transition temperature of the polymer‐laminated steel sheet was 15°C–30°C higher than the corresponding glass transition temperature of the laminated polymer.
Starch urea formaldehyde matrix encapsulation of solid agrochemicals. I. Matrix synthesis and characterizations
Authors: Rajagopalan N. , Shukla P. G. , Bhaskar C. , Banker V. S. , Dharia J. R. , Khilar Kartic C.
Published: April 2003

A starch urea formaldehyde (starch‐UF) matrix has been studied for application to the encapsulation of a solid insecticide. The pertinent parameters relating to the matrix synthesis have been identified and the influences of these parameters on release of the insecticide from the starch UF matrix have been investigated. The key parameter controlling the rate of release is the urea to starch ratio. It is shown that the release process can be described in terms of the generalized equation Mt/M∞ = ktn where k and n vary with system variables.
Epoxy resins based on aromatic glycidylamines. VI. Toughening of N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylmethane by reactive additives
Authors: Dobáš I. , Luňák S. , Zelenka J. , Horálek J. , Špaček V. , de Petris S.
Published: April 2003

Mechanical properties of N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylmethane and its mixtures with liquid bisphenol A‐type epoxy resins, bisphenol A and ε‐caprolactone have been studied. 4,4′‐Diaminodiphenylsulfone was used as hardener. Materials with improved fracture toughness and good mechanical strength in the temperature range 20–200°C have been formulated.
Synthesis and properties of cationic resins derived from urethane‐modified epoxy resins and methylethanolamine
Authors: Yang Chin‐Ping , Lee Lung‐Ta
Published: April 2003

Six urethane‐modified cationic resins were synthesized by reacting half‐blocked polyglycoltoluene diisocyanate–urethane (half‐blocked‐PG–TDI–urethane) and 2‐ethylhexanol‐blocked toluene diisocyanate (2‐EH‐blocked‐TDI) modified epoxy resins with methylethanolamine and subsequent neutralization with acetic acid. Three different polyglycols were used to react with toluene diisocyanate to from isocyanate‐terminated urethanes (1a–c) and subsequently two different monoalcohols were added to react with 1a–c to give half‐blocked‐PG‐TDI‐urethanes (2a–f). These cationic resins were then dissolved in suitable solvents and mixed with deionized water to form emulsions. The crosslinking properties, emulsion, and electrodeposition properties of these resins were studied in some detail. The deposition yields of emulsions prepared from urethane‐modified epoxy resins were higher than those of other emulsions. The pencil hardness of the crosslinked films of urethane‐modified resins were lower than that of non‐urethane‐modified resin. The emulsion and electrodeposition properties of the cationic resins were also deeply affected by the nature of the pendant positively charged group contained in the resins.
GC/MS and PGC/MS analyses of plasma polymerization for benzaldehyde
Authors: Zhao Qiang , Zhu Yufen , Cai Minxi , Xie Mandan , Liu Xueshu
Published: April 2003

Gas chromatography/mass spectrometry studies of gas condensates in plasma and pyrolysis products of plasma polymer for benzaldehyde were made. Both products' analyses indicate the significant presence of benzyl and carbonyl groups in plasma polymer samples. Infrared measurements were also used to correlate the structures suggested by GC/MS results. A radical mechanism, which involved hydrogen abstraction, aldehyde group abstraction, and benzyl fragmentation under plasma activation, was proposed. The highly crosslinked and branched structures of the plasma polymer were attributed to the subsequent reactivity of free radicals, formed as a result of the scission of the chemical bonds in the benzaldehyde molecules.
Specific interaction of starch and polyvinyl alcohols having long alkyl groups
Authors: Okaya Takuji , Kohno Hiroji , Terada Kazutoshi , Sato Toshiaki , Maruyama Hitoshi , Yamauchi Junnosuke
Published: April 2003

Properties of aqueous solutions of blends of starch and polyvinyl alcohols (PVAs), having alkyl groups as side chains, or at one polymer chain end, were studied in terms of viscosity stability, and transparency. In the case of corn starch, PVAs having butyl, octyl, and dodecyl end groups, as well as PVA copolymers containing small amounts of vinyl versatate, together with itaconic acid, increased the stability of the blended solution. The aqueous solutions of PVA, having dodecyl end groups and oxidized starch blend, also showed good stability in viscosities and considerable increase in transparency, whereas conventional PVA and oxidized starch blend gave turbid aqueous solutions, followed by phase separation. The phenomena were assumed to arise from the interaction of the alkyl group in PVA with starch, forming a helical structure with the alkyl group in the hydrophobic internal part.
Dielectric and viscoelastic properties of some meta‐tetramethyl xylene diisocyanate‐based polyurethanes as a function of sample composition
Authors: Capps Rodger N. , Stack Gary M. , Samuels Mary Q. , Beumel Linda L.
Published: April 2003

A series of linear segmented polyurethanes were synthesized, based on soft segments of polycaprolactone having an average number molecular weight of 2100, or hydroxy–terminated polybutadiene having an approximate molecular weight of 2800. Hara segments were made of meta–tetramethyl xylene diisocyanate and diethyl toluene diamine. The dynamic Young's modulus and loss tangent, relative permittivity, and dielectric loss, were found to be significantly affected by soft segment polarity and hard segment content. These results are discussed in terms of polymer morphology, such as degree of phase separation and soft segment phase state.
Toughening of polystyrene and poly(phenylene oxide) matrices with elastomeric styrene‐based block copolymers: Role of molecular architecture
Authors: Park Inha , Keskkula H. , Paul D. R.
Published: April 2003

The effects of the molecular architecture of elastomeric styrene‐based block copolymers on efficiency of toughening a brittle (polystyrene) and a ductile [a miscible blend of 80% phenylene oxide copolymer and 20% polystyrene (80PEC)] polymer were explored experimentally. Toughening appears to be mainly controlled by the blend morphology, which is determined by the rheological characteristics of the block copolymer relative to that of the matrix. The formation of dispersed particles during melt blending in a Brabender Plasticorder is strongly influenced by the ratio of the matrix and block copolymer viscosities (estimated here by Brabender torque). The size of the dispersed particles was found to be proportional to the 1.77 power of the torque ratio when this ratio is greater than unity. Thus, to a first approximation the effect of block copolymer architecture on toughening efficiency is related to how this structure affects the rheological behavior of the copolymer. Excellent toughness of polystyrene was achieved when the particle size was larger than 1–2 μm. The 80PEC resin is best toughened by block copolymers that form a cocontinuous phase morphology. The extent of toughening of this matrix appears to be a strong function of the styrene block molecular weight, whereas this structural feature seems to have no significant effect in toughening polystyrene.
Photografting of acrylic monomers on polystyrene support
Authors: Ajayaghosh A. , Das S.
Published: April 2003

Polystyrene xanthates, prepared through the reaction of chloromethylated polystyrene resins with potassium O‐ethyl xanthate, have been used for the photografting of acrylic monomers. Monomers such as acrylamide, acrylic acid, methacrylic acid, and methyl methacrylate were grafted onto the xanthate polymers on irradiation with a 450 W medium‐pressure mercury lamp (Hanovia). Among these monomers, the maximum graft efficiency was obtained for methyl methacrylate. The effect of cross‐link density of the xanthate polymer on the percentage graft yield was also studied. Scanning electron microscopic studies have shown that appreciable grafting has taken place on the surface of the polymer in a uniform manner. © 1992 John Wiley & Sons, Inc.
Kinetics of reaction of C36 dimeric fatty acids and ethylenediamine in solution
Authors: Vedanayagam H. Sumathi , Kale Vijay , Subbarao R.
Published: April 2003

Kinetic studies were carried out on the reaction between ethylenediamine and C36 dimeric fatty acids using benzyl alcohol as solvent. The reaction was performed at four different temperatures in the range of 160–190°C, and the products were analyzed for acid and amine values intermittently to follow the reaction. The fall in both the values was almost the same throughout the reaction. The kinetics was determined from the fall in acid value, and the reaction was found to be of overall third order and had an activation energy of 30.7 kcal mol−1 (128.5 kJ mol−1).
Influence of polymer characteristics and melt‐spinning conditions on the production of fine denier poly(ethylene terephtalate) fibers. Part III. Structure and properties of fine denier as‐spun PET fibers
Authors: Kiang Chang T. , Cuculo John A.
Published: April 2003

The effect of decreasing take‐up denier on the structure and mechanical properties of asspun poly(ethylene terephtalate) (PET) fibers is shown to be, in general, similar to an increase of take‐up velocity. Both can be related to increased threadline cooling rate and increased spinline stress that control the structure development in the threadline. However, important distinctions were observed in the orientation and crystallization effects due to decrease of take‐up denier or increase of take‐up velocity. These distinctions were explained on the basis of the threadline dynamics study of the fine denier PET fiber in the high‐speed spinning process, discussed in Part II of this study. Other properties, such as the dynamic mechanical properties and dye uptake, are not related to individual structure parameters, depending on the overall changes in structure, e.g., as given by the free volume.
Synthesis of chloral derivative of maleimide and its copolymerization with styrene
Authors: Sikorski Ryszard Tadeusz , Mirkiewicz Grażyna
Published: April 2003

A new monomer N‐(1‐acetoxy‐2,2,2‐trichloroethyl)maleimide (MI) and its copolymer with styrene have been developed. It was found that MI can be synthesized from N‐(1‐hydroxy‐2,2,2‐trichloroethyl)maleamide in acetic anhydride with a yield of 65%. The radical copolymerization of MI with styrene in benzene solution occurs with a yield of 91%. The obtained copolymer has a melting point about 215°C, good thermal resistance, and is selfextinguishing. The monomer and copolymer compositions were determined by elementary, 1H‐NMR and IR analysis.
Synthesis and characterization of pH‐ and/or temperature‐sensitive hydrogels
Authors: Park Tae Gwan , Hoffman Allan S.
Published: April 2003

A series of pH‐sensitive hydrogels that exhibit volume phase transition phenomena have been synthesized in aqueous solution and characterized with respect to their dynamic swelling behaviors. Positively charged hydrogels were prepared by copolymerizing varying ratios of N‐isopropylacrylamide and NN′‐dimethylaminopropylmethacrylamide. The hydrogels based on a temperature‐sensitive hydrogel demonstrate a large change of equilibrium swelling in response to small variations of pH and/or temperature. These hydrogels exhibit different lower critical solution temperature (LCST) ranges depending on the environmental pH values. Below their LCST, they exhibit small and broad pH sensitivities normally observed in most hydrophilic polyelectrolyte gels, but above their LCST, they exhibit sharp pH dependent phase transition behaviors. The pH‐dependent phase transition is strongly affected by temperature, while the temperature‐dependent transition is, in turn, largely influenced by the pH. As the temperature is raised, the transitional degree of gel swelling change becomes sharper and larger, and the phase transition pH value shifts to a lower pH. It was also found that swelling is faster than deswelling for these cationic hydrogels, which suggests the existence of a water diffusion barrier during the deswelling. The swelling kinetics of initially dry and glassy gels were strongly dependent on both the pH value and temperature.