bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical stability of trimethylolpropane trimethacrylate‐based polymers
Authors: Schmid Andrea , Walenius Maria , Flodin Per
Published: April 2003

Trimethylolpropane trimethacrylate (TRIM) was homopolymerized and copolymerized with methyl methacrylate (MMA), glycidyl methacrylate (GMA), and acrylamide (AA), respectively, in various solvents and at various temperatures. For comparison, poly(styrene‐co‐divinyl benzene) [poly(S‐co‐DVB)] gels were selected. The mechanical stability was measured by compression of the swollen gels. The porogen served as swelling agent. The compression moduli increased with increasing TRIM concentration in the polymerization. The compression moduli of poly(TRIM) could be increased by copolymerization with low concentrations of comonomer. Low polymerization temperature decreased the mechanical strength of poly(TRIM). A good solvent increased the compression modulus. TRIM‐based gels were at least as mechanically stable as were poly(S‐co‐DVB) gels.
New approach for the estimation of kinetic parameters in emulsion polymerization systems. II. Homopolymerization under conditions where n̄ > 0.5
Authors: Barandiaran María J. , Adams Mary E. , Cal José C. De La , Sudol E. David , Asua José M.
Published: April 2003

A new approach for the estimation of kinetic parameters in emulsion polymerization systems in which the average number of radicals per particle exceeds 0.5 is presented. The approach uses the time evolution of the conversion in chemically initiated systems and is based on a model that includes fundamental parameters such as the propagation rate constant, kp, the termination rate constant in the polymer particles, kt, the rate coefficient for initiator decomposition, kI, and the entry, ka, and exit, kd, rate coefficients. It was found that kp, kt, kI, ka, and, under some circumstances, kd can be accurately estimated provided that termination in the aqueous phase is significant. When the extent of the aqueous phase termination is negligible, only kp, kt, and kI can be estimated. The effect of both the experimental noise level and the run‐to‐run irreproducibility on the accuracy of the estimates was studied. In addition, it was found that significant inaccuracies resulted from the poor determination of the exact time when polymerization begins. A method to circumvent this problem was proposed.
Influence of polymer characteristics and melt‐spinning conditions on the production of fine denier poly(ethylene terephtalate) fibers. Part II. Melt spinning dynamics
Authors: Kiang Chang T. , Cuculo John A.
Published: April 2003

The effect of poly(ethylene terephtalate) (PET) polymers with different rheological properties as well as the effect of different spinning conditions on the minimum attainable takeup denier were determined. The spinning conditions were modified by the use of heating devices, insulation plate, and convergence guides tested in the range of take‐up speeds from 2000 to 6000 m/min. It is postulated that the important parameter in the production of fine denier PET fiber is the spinline tension level, which must be kept low in order to obtain finer denier fibers. The increase of take‐up velocity and the threadline length increase the spinline stress level, and therefore the minimum denier attainable increases. The effect of the apparent elongational viscosity of the polymer and the threadline cooling profile can be thought as affecting the draw‐down tension and therefore the minimum take‐up denier. Higher apparent elongational viscosity level or faster cooling generates higher spinline tension resulting in higher minimum denier. The effects of the apparent elongational viscosity is more significant at a speed of 5000 m/min. This is in part due to the already very small denier obtained at speeds up to 4000 m/min, where the conditions of uniformity of polymer flow seem to be more important.
Studies of the solid‐state thermal degradation of PVC. I. Autocatalysis by hydrogen chloride
Authors: Patel K. , Velazquez A. , Calderon H. S. , Brown G. R.
Published: April 2003

The thermal degradation of virgin and HCI‐treated PVC in powder form, as well as of PVC films of different thicknesses, has been studied as a function of time and temperature. The rate of dehydrochlorination was determined conductimetrically and from the polyene sequence distributions as obtained by UV spectroscopy. Increases in the rate of dehydrochlorination, ranging between 30 and 45%, were observed at all temperatures for the samples pretreated with HCI, while the corresponding activation energies were found to be lower by about 20%. For the PVC films, the rate increased with thickness, i.e., with longer residence time of evolved HCI within the sample. The results offer insight regarding the autocatalytic role of evolved HCI.
An FTIR–ATR investigation of in vivo poly(ether urethane) degradation
Authors: Wu Y. , Sellitti C. , Anderson J. M. , Hiltner A. , Lodoen G. A. , Payet C. R.
Published: April 2003

Surface degradation of implanted poly(ether urethane)s was studied quantitatively with a micro‐ATR–FTIR technique. Substantial degradation was observed particularly in the soft segment at the α‐carbon adjacent to the ether linkage. The degradation caused changes in the concentration profiles of the soft‐segment groups in the depth direction, and the affected depth was up to 10 microns after implantation for 10 weeks. Inhibition of degradation by antioxidants indicated the oxidative nature of degradation. An in vivo poly(ether urethane) degradation mechanism was proposed.
Determination of the kinetic parameters for the polymerization of a polyurethane using an improved method of differential scanning calorimetry
Authors: Hernández‐Sánchez F. , Vera‐Graziano R.
Published: April 2003

The kinetic parameters for the polymerization reactions of two polyurethane systems were determined by using an improved method of differential scanning calorymetry (DSC). The calculated activation energy, reaction order, and Arrhenius prefactor show good correlation with the experimental results. The method used here shows several improvements as respects to other DSC methods: the three kinetic parameters can be calculated directly; it is more accurate than other DSC methods; and it requires only one heating rate, during the calorimetric experiments, to determine the activation energy.
Study on PVA hydrogel crosslinked by epichlorohydrin
Authors: Bo Jiang
Published: April 2003

Poly(vinyl alcohol) hydrogel was prepared by using epichlorohydrin as a crosslinking agent. The molecular weight between crosslinks was calculated. The swelling behavior, as well as mechanical properties, of the hydrogels were examined by weighing and tensile testing, respectively. Values of equilibrium water content of more than 95% were reached while Young's modulus and tensile strength of the hydrogels were about 105 dyn/cm2. Crystallization was introduced by drying the hydrogels at 90°C. The dried hydrogel samples were used for swelling kinetic study, then reequilibrated with water and subjected again to tensile testing. Due to the formation of microcrystalline domains in the PVA hydrogel network after annealing, hydrogels with greatly enhanced Young's modulus, tensile strength, and elongation at break were obtained and their equilibrium water content values remained still high, i.e., 87 and 93%. © 1992 John Wiley & Sons, Inc.
Transesterification reaction of poly(ethylene‐co‐vinyl acetate) with alcohols: A kinetic study in solution and in the bulk
Authors: Hu G. H. , Lindt J. T. , Lambla M.
Published: April 2003

The chemical kinetics of the transesterification reaction of poly(ethylene‐co‐vinyl acetate) (EVA) with aliphatic alcohols were investigated, both in solution and in bulk, in the presence of dibutyl tin dilaurate (DBTDL) as the catalyst. A Fourier Transform infrared spectrometer (FTIR) was utilized for the measurement of the extent of the reaction. Experimental results showed that the reaction carried out in solution and in the bulk follows the same mechanism, namely, a reversible second order reaction of which the equilibrium only slightly increases with temperature. Additionally, the overall forward and reverse rate constants are proportional to the square root of the concentration of the catalyst. This study has also revealed that the intrinsic rate constants in solution and in the bulk are the same, regardless of the differences in the physical conditions encountered in the bulk and solution media, in particular, the reactant concentrations and viscosity of the reacting mixture. The effects of mechanical mixing are unimportant, since the reaction rate is relatively slow as compared with the rate of diffusion.
Annealing of commercial block polypropylene. II. Behavior of poly(ethylene‐co‐propylene) component
Authors: Ito Jun‐Ichi , Mitani Katsuo , Mizutani Yukio
Published: April 2003

Moldings of ethylene–propylene block copolymer (block PP) are improved by annealing in their tensile impact strength (TIS) and brittle temperature (Tb). To elucidate the mechanism, the role of the poly(ethylene‐co‐propylene) (PEP) component was studied, and the component extracted with n‐heptane from annealed test pieces was subjected to characterization by a fractionation technique. It is found that recrystallization takes place by annealing in the PP matrix and results in segregation of atactic PP and high molecular weight amorphous PEP from the crystal region to the amorphous region. Furthermore, crystalline PEP also undergoes recrystallization by annealing, increasing the miscibility in the interface of PP and PEP. These phenomena in the solid phase are discussed in connection with the annealing effect related to impact strength. © 1992 John Wiley & Sons, Inc.
Syntheses of polyethylene glycol (PEG) with different functional groups at each end. I. Preparation of monotrityl PEG using polyvinyl alcohol (PVA) matrix
Authors: Huang Junlian
Published: April 2003

The syntheses and separation of monotrityl PEGs with molecular weights in the range of 400–6000 were successful using PVA as matrix. The yield of monotrityl PEG is strongly dependent on the initial mole ratio of PEG—trityl chloride. It is observed that satisfactory results can only be obtained in the range of 1 : 1.7 to 1 : 2.4 (mole number of PEG/mole number of trityl chloride). The effect of reaction conditions on monosubstitution is discussed. © 1992 John Wiley & Sons, Inc.
Grafting of acrylic acid onto corona‐treated polyethylene surfaces
Authors: Olafsen K. , Stori A. , Tellefsen D. A.
Published: April 2003

Peroxides formed on the surface by corona treatment of low‐density polyethylene film can be used to initiate grafting of polar vinyl monomers such as acrylic acid. Different types of peroxides are probably formed on the surface, but at least hydroperoxides could be detected by XPS analysis. The grafting reaction was carried out directly after corona treatment, by placing the corona‐treated film above a solution of acrylic acid heated to 100°C. The grafting reaction takes place in a vapor phase of the monomer. After extracting the reacted films with hot methanol and drying, surface analysis by XPS, IR, and contact angle measurements were carried out. Effect of degree of corona treatment and reaction time have been studied. The conclusion from this work is that acrylic acid in vapor phase can successfully be grafted onto corona‐treated polyethylene film by this method. © 1992 John Wiley & Sons, Inc.
Effect of cardinyl acrylate on thermal behavior of methyl methacrylate copolymers
Authors: Agarwal Seema , Choudhary V. , Varma I. K.
Published: April 2003

Cardinyl acrylate (CA), prepared by the reaction of acryloyl chloride and cardinol, was copolymerized with methyl methacrylate (MMA) in bulk at 80°C using 2% benzoyl peroxide as an initiator. The copolymer composition was determined by 1H‐NMR spectroscopy. Three copolymer samples containing 0.0048–0.0838 mol fraction of cardinyl acrylate were obtained. A significant improvement in the thermal stability of MMA was observed by incorporating 0.0048–0.0838 mol fraction of CA in the backbone. The activation energy for decomposition in the temperature range 350–480°C for copolymers was higher than PMMA. © 1992 John Wiley & Sons, Inc.
Vibration damping with urethane/acrylate simultaneous semi‐interpenetrating polymer networks
Authors: Tung Chein‐Jen , Hsu Tzu‐Chien J.
Published: April 2003

The vibration damping efficiency of the IPN‐laminated steel sheet, which consisted of a viscoelastic IPN layer sandwiched between two steel sheets, was investigated in this study. The simultaneous semi‐IPN used included an elastomeric urethane phase and a glassy acrylate phase. This study seeks to develop a laminate, with broader damping temperature and frequency ranges, in contrast to the homopolymer‐based laminates studied previously. A vibration damping analysis of the neat IPNs was first conducted using a dynamic rheometer in order to provide basic rheological properties of the neat IPNs. This was followed by the frequency spectrum analysis of the IPN‐based laminates, using a frequency analyzer, utilizing the results derived from the damping analysis of the neat IPNs. The IPN variables studied included the reaction temperature, the amount of the catalyst for urethane phase, the composition in acrylate phase and in urethane phase, and the composition of IPN. The results indicated that, by properly adjusting the IPN parameters, the extent of phase separation in IPN could be controlled. The effect of the network formation in the catalyzed urethane phase on the damping properties of IPNs was also investigated and the possible reaction mechanism was analyzed. The IPNs with catalyzed urethane phase showed single, smooth damping curves with peak values of tan δ = 0.4–0.7 in a broad temperature range. The study was then extended to the analysis of the vibration damping efficiency of the IPN‐based laminated, including the effect of IPN composition, the effect of the urethane composition in IPN, and the effect of the acrylate composition in IPN. The results indicated that the IPN‐based laminates yielded a maximum loss factor in the range of 0.1–0.5, which was below the tan δ value of IPN, but was better than that of the neat steel sheet. In addition, most of the damping properties of the laminates could be derived or predicted from the dynamic rheological properties of the neat IPNs. Thus, knowing the basic dynamic rheological properties of the neat IPNs is vital for a successful design and application of the IPN‐laminated steel sheet. © 1992 John Wiley & Sons, Inc.
Dynamic‐mechanical behavior of highly drawn isotactic polypropylene
Authors: De Candia F. , Romano G. , Baranov A. O. , Prut E. V.
Published: April 2003

Fibers of isotactic polypropylene were obtained by high‐temperature drawing, adopting a two‐stage process. Very high drawing degrees were achieved, more than 40. The physical behavior was analyzed by determining the dynamic‐mechanical relaxation spectra in monoaxial stretching. The results obtained show that the elastic modulus reaches a saturation value at deformation degrees of about 20, well below the drawability upper limit, indicating that above 20 any further drawing does not affect the structure. Moreover the α transition appears weak or absent in the drawn samples, while the β transition is still readily detectable. Both effects agree with Peterlin's model of drawing and with the fiber structure. © 1992 John Wiley & Sons, Inc.
Blends of polyamide 6 and bisphenol‐A polycarbonate. Effects of interchange reactions on morphology and mechanical properties
Authors: Gattiglia E. , Turturro A. , Lamantia F. P. , Valenza A.
Published: April 2003

Blends of polyamide 6 (PA6) and polycarbonate (PC) were prepared in a Brabender mixer, at 240°C, applying long mixing time, for 45 min. It was observed that the morphology and the mechanical properties tend to resemble those of a homogeneous material as the mixing time and PA6 concentration increase. This is attributed to chemical reactions taking place between the two homopolymers. Acidolysis, amidolysis, and aminolysis, catalyzed by the terminals and the amide groups of the polyamide, should in principle be possible. Our results indicate that the aminolysis is the main process, inducing simultaneously scission of PC chains and formation of PC‐PA6 copolymer chains. The latter act as interfacial agents between incompatible PA6 and PC, improving the mechanical properties of PA6‐rich blends, in agreement with the predictions of some theoretical models assuming good phase interpenetration. © 1992 John Wiley & Sons, Inc.
Structure of heat‐treated nylon 6 fibers. I. Application of the arrhenius equation
Authors: De Godoy Oriani Luis Alberto , Simal Abigail Lisbão
Published: April 2003

The changes in lateral order, crystalline perfection index, crystallinity percentage, long period, and shrinkage denote the structural modification due to thermal effects in the heat‐treated nylon 6 fibers. The application of the Arrhenius equation to these parameters resulted in two types of behavior: the parameters long period and shrinkage showed linearity in the temperature range of 100–190°C, while the others presented linearity between 150 and 190°C. The first reflects the direct dependence of crystal growth on shrinkage and the latter shows that the necessary energy to promote significant crystal growth and perfection will be reached only at 150°C. In the range of temperature from 100 to 150°C the observed increase of crystallinity is associated to chain flexibility allowing rearrangement as well as new crystal formation. This phenomenon seems to be related to the discontinuity observed in the Arrhenius plots in the same range of temperature. © 1992 John Wiley & Sons, Inc.
Use of spherical tannin resin as a support for immobilized enzyme
Authors: Yamaguchi Haruhiko , Miura Kouji , Higuchi Mitsuo , Sakata Isao
Published: April 2003

α‐Amylase (α‐1, 4‐glucan 4‐glucanohydrolase 3.2.1.1) was used to investigate whether the spherical tannin resins made by the reaction of Mimosa (Acacia Mollissima, Wattle) tannin (condensed‐type tannin) (MT) with formaldehyde could be used as a support for the immobilization of enzymes. It was found that the optimum pH range of the immobilized α‐amylase was wider than that of native α‐amylase, and the shelf life of the enzyme was increased by immobilization. Furthermore, the immobilized enzyme could be used repeatedly, and in a continuous enzyme reaction increased a further advantage of the technique. On the basis of these data, it was concluded that this resin could be used as a support for the immobilization of enzymes. © 1992 John Wiley & Sons, Inc.
Impact failure of poly(methyl methacrylate)
Authors: Bevan L. , Reed P. E.
Published: April 2003

Damage development during instrumented falling weight impact (IFWIM) testing of poly(methyl methacrylate) (PMMA) is recorded using short pulse photography. The first visible damage is cracking on application of the peak force. Finite element analysis predicts the deformation and state of stress throughout the specimen until the first point of failure is reached. A variation in the specimen geometry produces a significant change in initial failure energy, while the maximum tensile stress is approximately constant. The proposed failure criterion is the attainment of a critical time‐dependent value of tensile stress. © 1992 John Wiley & Sons, Inc.
Synthesis and characterization of suspension‐polymerized poly(vinyl alcohol) beads with core–shell structure
Authors: Kim Cherng‐Ju , Lee Ping I.
Published: April 2003

A new method of preparing large spherical PVA beads (up to 1.5 mm diameter) with a core‐shell structure has been developed. This involves a stepwise saponification of suspension polymerized PVAc beads, followed by a stepwise crosslinking of the PVA core and shell with glutaraldehyde. The resulting composite PVA beads have thin, highly crosslinked outer shells and lightly to moderately crosslinked inner cores of different degrees of crosslinking. In addition to the characterization of structural parameters, the kinetics of solute release and the swelling dynamics, including the transient dimensional changes, have been investigated using proxyphylline as a model compound. © 1992 John Wiley & Sons, Inc.
Adhesion enhancement of rubbery and ductile polyolefin coatings on glass fibers for epoxy composites and effects on failure mechanism
Authors: Mascia L. , Dhillon J. , Harper J. F.
Published: April 2003

Dilute polyolefin solutions, respectively based on EPDM and UHMWPE, were reacted with functionalized silanes to prepare coatings for glass fibers. These were found to provide adequate bonding characteristics for both glass and epoxy resin (bisphenol type). Unidirectional composites containing fiber matrix interlayers, using fibers coated with the aforementioned functionalized polyolefins, were found to exhibit much larger tanδ values over the temperature range of 60 to +60°C and greater ductility in flexural tests, albeit at the expense of a reduction in failure stresses. The UHMWPE coatings produced a multiple step fracture mechanism, which was deemed to provide a more efficient crack stopping mechanism than equivalent EPDM coated fibers. © 1993 John Wiley & Sons, Inc.
Studies on the grafting of methyl methacrylate onto polyacrylonitrile
Authors: Asaduzzaman A. K. M. , Raval Heta , Devi Surekha
Published: April 2003

Grafting of methyl methacrylate onto polyacrylonitrile was carried out using benzoyl peroxide as initiator and dimethylformamide as solvent. The occurrence of grafting was confirmed by IR spectroscopy and SEM analysis. Effects of various parameters such as reaction time, reaction temperature, initiator concentration, and monomer concentration on rate of polymerization, percentage grafting, and grafting efficiency were studied. The graft copolymers were found to have the similar thermal and structural properties like virgin polyacrylonitrile. Decreasing extent of swelling was observed for the polymers of higher percentage graft in polar solvents. © 1993 John Wiley & Sons, Inc.
Thermal behaviour and adhesive properties of some cyanoacrylate adhesives with increased heat resistance
Authors: Denchev Z. Z. , Kabaivanov V. S.
Published: April 2003

Cured adhesive layers produced from ethyl‐(ECA), allyl‐(ACA), and allyloxyethyl‐(AOECA) 2‐cyanoacrylates were studied by means of thermogravimetry and differential scanning calorimetry. Polymer films of ECA‐based adhesive compositions comprising various amounts and types of 2‐cyano‐2,4‐pentadienoic acid (CPDA) esters were also examined. The influence of the modifier type, as well as the chemical structure of the cyanoacrylates used, was followed upon the glass transition temperatures (Tg) and the rates of thermal degradation of the corresponding polymers. In the case of cured adhesive mixtures containing unsaturated CPDA esters and when poly(ACA) and poly(AOECA) were studied, a significant increase of their heat resistance was established, as compared with poly(ECA). This fact was explained with the formation of three‐dimensional structure of the polymer film due to crosslinking reactions. A different course and character of these reactions were found comparing the thermal behavior of poly(ACA) and cured compositions containing unsaturated CPDA esters. A good agreement was found between data from the thermal analyses and the tensile shear and impact strength tests. It was shown that the modification of ECA with unsaturated CPDA esters is a possible way of increasing the heat resistance of the basic adhesive. © 1993 John Wiley & Sons, Inc.
Photodegradation of oxidized cotton cellulose
Authors: Buschle‐Diller Gisela , Zeronian S. Haig
Published: April 2003

Different functional groups were systematically introduced into cotton cellulose and their effect on the stability of cotton toward photochemical degradation was examined. First, the cotton was progressively oxidized with sodium metaperiodate up to an oxygen consumption of 2.45 atom per 100 anhydroglucose units (agu) to form 2,3‐dialdehyde cellulose. These products were reduced with potassium borohydride to obtain 2,3‐dialcohol cellulose or were oxidized with sodium chlorite to obtain 2,3‐dicarboxyl cellulose. The chemical modifications of the cellulose structure caused a drop in tensile strength of 34% for the dialdehyde of 2.45 oxygen consumption per 100 agu compared to 27% and 37% in the case of the dialcohol and the dicarboxyl celluloses, respectively. Upon irradiation with UV light, the breaking strengths of the dialcohol and the dicarboxyl celluloses were generally higher up to an oxygen consumption of 0.63 per 100 agu when compared to the dialdehyde and then fell more drastically. The tensile data of the exposed oxycelluloses correlated well with the reciprocal of their intrinsic viscosities (R2 = 0.89). The primary alcohol groups appeared to accelerate the progress of the photochemical degradation. The photochemical effects of the carboxyl groups could not be differentiated from the autohydrolysis to which dicarboxyl cellulose is susceptible. No indication of a change in morphology was detected for any of the treatment types. © 1993 John Wiley & Sons, Inc.
Cure of epoxy novolacs with aromatic diamines. I. Vitrification, gelation, and reaction kinetics
Authors: Oyanguren P. A. , Williams R. J. J.
Published: April 2003

The cure reaction of a commercial epoxidized novolac with 4,4' diaminodiphenylsulfone (DDS) was studied at constant cure temperatures in the range 120–270°C, as well as at constant heating rates (differential scanning calorimetry, DSC). Stoichiometric formulations did not attain complete conversion due to the presence of topological restrictions. The limiting conversion was xmax = 0.8. Samples containing an amine excess (≥ 20%) could be completely reacted, whereas this was not possible for formulations containing an epoxy excess. Samples containing a 20% amine excess showed the maximum value of the glass transition temperature (Tg230°C). Cure took place by epoxy‐amine hydrogen reactions catalyzed by (OH) groups. A reactivity ratio of secondary to primary amine hydrogens equal to 0.2 was found. The activation energy was E = 61 kJ/mol, as arising from Tg versus time shift factors and time to gel measurements. A unique relationship between Tg and x could be obtained. Gelation took place at xgel = 0.45 and the maximum Tg for the stoichiometric system was Tgmax = 215°C for x = 0.8. A conversion versus temperature transformation diagram was used to represent conditions where gelation, vitrification, degradation, and topological limitations took place. © 1993 John Wiley & Sons, Inc.
Tensile properties of short sisal fiber‐reinforced polyethylene composites
Authors: Joseph Kuruvilla , Thomas Sabu , Pavithran C. , Brahmakumar M.
Published: April 2003

Sisal fibers (Agave‐Veracruz) have been used as reinforcements in low‐density polyethylene (LDPE). The influence of the processing method and the effect of fiber content, fiber length, and orientation on tensile properties of the composites have been evaluated. The fiber damage that normally occurs during blending of fiber and polyethylene by the meltmixing method is avoided by adopting a solution‐mixing procedure. The tensile properties of the composites thus prepared show a gradual increase with fiber content. The properties also increased with fiber length, to a maximum at a fiber length of about 6 mm. Unidirectional alignment of the short fibers achieved by an extrusion process enhanced the tensile strength and modulus of the composites along the axis of fiber alignment by more than twofold compared to randomly oriented fiber composites. © 1993 John Wiley & Sons, Inc.
Identification of volatile compounds resulting from the thermal oxidation of polyethylene
Authors: Bravo A. , Hotchkiss J. H.
Published: April 2003

The migration of compounds from polymer‐based packaging may impart undesirable odors to foods. We, therefore, undertook a study of the volatile compounds produced during the heating of polyethylene (PE) in the presence of excess O2 at temperatures of 150–350°C and for heating times of 5–15 min. Eightyfour volatile compounds in the range of C5—C23 were identified by gas chromatography mass spectrometry. The major products were aliphatic hydrocarbons, aldehydes, ketones, and olefins. Changes in temperature and heating times affected the amount and type of compounds produced, with hexanal being found in the largest amount and 300°C resulting in the greatest quantity of volatile compounds. At 350°C, greater amounts and numbers of low‐boiling and fewer high‐boiling compounds were formed. Only small amounts of volatiles were produced at 150°C. Many of the compounds identified have been reported to have odor and/or toxicological significance. © 1993 John Wiley & Sons, Inc.
Emulsification and electrodeposition of mixtures of cationic resins. I. Cationic resin and nonionic cross‐linker
Authors: Yang Chin‐Ping , Chen Yahn‐Haur
Published: April 2003

The emulsification and electrodeposition properties of two resins system (cationic epoxyamine adduct,III, was the main resin; nonionic trimethylolpropane–toluene diisocyanate‐2‐ethylhexanol resin,II, was used as cross‐linker) were investigated and the compositions of their electrodeposited films were obtained by Fourier transform infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic behaviors. The optimum resin compositionof coemulsion was also found to provide the deposited film having the best properties. The results indicate that the molecules of nonionic cross‐linkerIIare entangled by the ones of cationic resinIIIduring the dispersion process and they can be codeposited on the cathodic substrate after a voltage has been applied. Moreover, at the condition of stable coemulsion of the two‐component system, the resin composition of electrodeposited film is almost equal to the resin composition of the coemulsion and is not affected by the applied voltage or resin concentration. © 1993 John Wiley & Sons, Inc.
A new method to predict the maximum packing fraction and the viscosity of solutions with a size distribution of suspended particles. II
Authors: Sudduth Richard D.
Published: April 2003

A new analysis technique has been developed in this paper to evaluate the upper limit of the packing fraction, φn utilized in the prediction of suspension viscosities. The semiempirical equation developed for the upper limit of the packing fraction, φn was generated initially from McGeary's binary particle packing fraction data. All possible Dx/Dy ratios of particles size averages were evaluated and analyzed in this formulation development. Only the D5/D1 and D4/D2 ratios of particle diameter averages were found to accurately predict the proper particle volume fraction location obtained in McGeary's data for the correct upper limit packing fraction φn. After developing methodology to calculate φn for binary particle distributions, an extension was made to include distributions with any number n of different particle size diameters. One of the more general of the suspended particle viscosity equations, as developed in a previous paper by this author, was used to demonstrate the application of this new φn methodology to the evaluation of suspension viscosity properties. The blended binary suspension viscosity results of Johnson and Kelsey for near monodisperse latexes were shown to be satisfactorily predicted as a function of the binary volume composition. © 1993 John Wiley & Sons, Inc.
Characterizing keratins using high‐pressure differential scanning calorimetry (HPDSC)
Authors: Wortmann F.‐J. , Deutz H.
Published: April 2003

Applying differential scanning calorimetry (DSC) for temperatures up to 180°C, the denaturation transition of the α‐helical material of various keratins in excess water was studied at conditions of equilibrium water vapor pressure (high‐pressure DSC). The results show a generally cystine content and material invariate denaturation range of 20–30°C with peak temperatures around 140°C. Though analysis of variance and multiple comparison tests show a pronounced inhomogeneity of the enthalpy data, the results generally support the material invariance of the denaturation enthalpy and hence of the helix content of the keratins. The denaturation enthalpy for the helical coiled‐coil‐structures in the intermediate filaments is determined as ΔH = 6.5–7.8 kJ/mol. A significant positive correlation was found between the denaturation temperatures and the cystine content. It is concluded, that the helix denaturation temperatures are kinetically controlled by the amount and/or the chemical composition of the surrounding nonhelical matrix, and that the double‐peak endotherms observed for wool and other keratins originate from two cell types that are sufficiently different in sulfur content to allow endotherm separation. In the case of wool the cell types can be identified as “ortho‐” and “paracortical” cells. © 1993 John Wiley & Sons, Inc.
Effect of a diazide as adhesive agent in elastomeric matrix–short polyamide fibers composite
Authors: Ibarra Luis , Jordá Carmina
Published: April 2003

The effect of a diazide, chemically bonded to short polyamide fibers, has been investigated in order to establish if the diazide acts effectively as a bond bridge between the elastomeric matrix and the fibers. Composite properties, such as green strength, solvent swelling, tensile and tear strength, and elongation at break, which clearly manifest the existence of a strong interface, have been measured in comparison with those obtained in a similar composite with a conventional adhesive system. Likewise, the temperature dependence of tan δ showed a dispersion peak in the temperature range 30–90°C, which corresponds to the addition of the two relaxations related to the fiber and the interface. © 1993 John Wiley & Sons, Inc.
The modification of nylon 6 by a phenol‐formaldehyde resin
Authors: Huang Misty W. , Zhu K. J. , Pearce Eli M. , Kwei T. K.
Published: April 2003

Modification of nylon 6 by blending with a small amount of a novolac resin has been investigated. Unexpected increased of Tg and tensile modulus and reduction in moisture absorption have been found at levels of novolac incorporation of 1–3 wt %. The small amount of novolac resin also has an effect on the crystallization and nylon 6 crystal structure (α vs. γ form). © 1993 John Wiley & Sons, Inc.
Synthesis and polymerization of lignin‐based macromonomers. III. Radical copolymerization of lignin‐based macromonomers with methyl methacrylate
Authors: Da Cunha C. , Deffieux A. , Fontanille M.
Published: April 2003

The radical copolymerization of methyl methacrylate (MMA) with lignin fragments (resulting from flash hydrolysis) functionalized by polymerizable groups is investigated. To transform lignin fragments into macromonomers, the anchoring of styrenyl and methacryloyl groups has been first studied; the optimal conditions for an etherification or an esterification of hydroxy functions in lignin residues, by chloromethylstyrene and methacryloyl chloride leading to lignin‐macromonomers of controlled size and functionality, have been investigated. The influence of experimental conditions on both the degree of substitution and the characteristics of functionalized lignin fragments is discussed; linear and cross‐linked lignin‐MMA copolymers have been prepared. The accurate control of the number of anchored polymerizable groups per lignin fragment is a determining step that establishes the dimensionality of the chains and therefore the processability of the prepared copolymers. “Linear” lignin‐MMA copolymers containing up to 40% in mass of lignin have been obtained and some structural aspects of the corresponding materials are examined. © 1993 John Wiley & Sons, Inc.
The influence of plasma gas species on the adhesion of thermoplastic to organic fibers
Authors: Pitt William G. , Lakenan John E. , Brent Strong A.
Published: April 2003

Adhesion between organic fibers and thermoplastics in a composite material is usually weak because of the lack of chemical and mechanical bonding. This study investigated the influence of plasma gas species in a novel technique to improve interfacial adhesion of Kevlar 49 fibers to polycarbonate. Single Kevlar fibers were exposed to radio‐frequency plasma discharge in atmospheres of argon, oxygen, and ammonia. Plasma treatment has been shown to generate reactive free radicals on polymer surfaces. The fibers that were coated immediately with a polycarbonate melt while still in the vacuum environment of a plasma reactor showed an increase in interfacial shear strength that was maximum at 4.1 s exposure and decreased at longer exposure times. At 4.1 s exposure, Ar and O2 plasma treatment increased shear strength by 20 and 18%, respectively. NH3 plasma treatment produced only a statistically insignificant increase at 4.1 s of exposure and a significant decrease in adhesion at 8.3 s of exposure. Fibers that were exposed to air for 1 h before coating showed no statistically significant increase or decrease in adhesion. The increase in adhesion of the directly coated fibers was attributed to free radical‐initiated formation of covalent bonds between the Kevlar and the polycarbonate. © 1993 John Wiley & Sons, Inc.
Dynamic mechanical properties of silica‐filled ethylene vinyl acetate rubber
Authors: Mukhopadhyay K. , Tripathy D. K. , De S. K.
Published: April 2003

Dynamic mechanical studies of ethylene vinyl acetate rubber indicated the presence of different transitions: the α‐transition or glass‐rubber transition temperature (Tg) at −17°C, the γ‐transition around −60 to −70°C observed as a shoulder, and the γ‐transition in the temperature region of −127 to −135°C, apart from a high‐temperature transition (T1,1) at +69°C. The α‐transition temperature did not shift its position with incorporation of silica filler, but there was gradual sequential lowering of tan δ peak values at Tg with increase in filler loading. Such sequential dependence of tan δ values on filler incorporation was not observed in the cases of β‐ and γ‐transitions. The T1,1 transition was found to be less prominent in the presence of filler, particularly at high concentration. Treatment of the filler with a silane coupling agent caused a shift in the α‐transition temperature to higher temperature by about 4°C. Studies on dynamic mechanical properties under isothermal conditions have shown that the coupling agent caused a breakdown of silica agglomerates during mixing. An increase in frequency caused a shift of tan δ peak positions in the α‐ and γ‐transition regions toward higher temperature. Although frequency did not have a significant effect on the tan δ value at the α‐transition, increase in frequency caused sequential lowering of tan δ value at the α‐transition. increase in frequency caused sequential lowering of tan δ value at the γ‐transition. In the high‐temperature region, the T1,1 peak exhibited by the gum compound gradully disappeared with increasing frequency. © 1993 John Wiley & Sons, Inc.
Relationship between cellulase treatment and the dyeability with a direct dye for various kinds of cellulosic fibers
Authors: Mori Reiko , Huga Toshio , Takagishi Toru
Published: April 2003

The cellulosic fibers were dyed to equilibrium with Congo Red before and after cellulase treatment. The fibers examined were rayon, polynozic, cupra, flax, and cotton. It was found that the volume term for dyeing (V) was associated with weight loss (WL) caused by the cellulase treatment, for the original fibers. Apparent affinity for dyeing (AF) for the cellulase‐treated fibers was calculated using a constant value of V obtained for each kind of the original fibers. The results led to the assumption that there would be two kinds of the regions that could be accessible to dye. One would be the region that was readily digested by the enzymatic hydrolysis. The other would be the region that was additionally developed by the attack of cellulase. The previously dyed fibers were hydrolyzed by cellulase. It was found that the physical bondings that formed between cellulose and Congo Red molecules would block the hydrolysis by cellulase for all the fibers examined. It was also assumed that there would be a region that could be accessible to cellulase but not entirely to Congo Red. © 1993 John Wiley & Sons, Inc.
Universal calibration assessment in aqueous gel permeation chromatography
Authors: Bahary W. S. , Jilani M.
Published: April 2003

It was the objective of this paper to assess the applicability of the universal calibration method to aqueous GPC/SEC with nonionic and anionic polymers using the Viscotek differential viscosity detector. Three water‐soluble polymers—polyacrylic acid, dextran, and polyethylene oxide—were chromatographed using four UltrahydrogelTM columns with 0.3 M NaCl and 0.1M KH2PO4 as the mobile phase adjusted to pH 7. Three distinct calibration curves were obtained. Upon addition of 10% methanol, a reasonably good universal calibration curve was obtained. However, quantitative analysis of the data exhibited about 5% deviation in average Mw and Mn for sodium polyacrylate as calculated from the single curve as opposed to about 40% when calculated from the composite curve. The applicability of three theoretical models for the universal calibration method was assessed, and a recommendation was made for future work. © 1993 John Wiley & Sons, Inc.
Studies on compatibilization of blends of polypropylene and a thermotropic liquid crystalline polymer
Authors: Heino Markku T. , Seppälä Jukka V.
Published: April 2003

Thermotropic liquid crystalline polymers, LCPs, are frequently blended with thermoplastics to achieve an in situ composite structure. Significant mechanical reinforcement is obtained for the matrix polymer in the direction of the LCP fibers, but the transversal properties are often inferior because of the incompatibility of the components. Blends of LCP with polypropylene, and with three related matrix polymers, and PP/LCP blends with added potential compatibilizers were prepared and studied for their mechanical properties and morphology. A notable improvement in impact strength was achieved when a small amount of ethylene‐based terpolymer was added as compatibilizer. © 1993 John Wiley & Sons, Inc.
Surface modification of polyethylene by remote dc discharge plasma treatment
Authors: Behnisch J. , Holländer A. , Zimmermann H.
Published: April 2003

The surface modification of polyethylene in a remote nitrogen, oxygen, and hydrogen dc discharge plasma was investigated. In the case of the nitrogen plasma a strong correlation exists between the concentration of active nitrogen species, as detected by Langmuir probe measurements and plasma emission spectroscopy, and the time dependence of the polymer surface modification, as detected by contact‐angle measurements. The obtained contact‐angle data were interpreted in terms of the acid–base model for the interaction of the test liquid with the polymer surface. There was a great similarity in the functionalization of the polyethylene surfaces treated with nitrogen as well as with oxygen plasma, except in the intial stage, where in the former, mainly functional groups acting as electron acceptors were formed, whereas in the latter a sharp increase in the content of both electron donor as well as electron acceptor groups was detected. Thus, a determining influence of oxygen residues in the remote nitrogen plasma was indicated. The absence of such an effect in the case of the hydrogen plasma could result from direct quenching of reactive oxygen species and / or the chemical reduction of formed oxygen containing functionalities by hydrogen species. © 1993 John Wiley & Sons, Inc.
Fibers from a soluble, fluorinated polyimide
Authors: Dorogy William E. , Clair Anne K. St.
Published: April 2003

Polyimide fibers have been produced from both polyamic acid and polyimide resins, derived from 2, 2‐bis (3,4‐dicarboxyphenyl) hexafluoropropane dianhydride and 2, 2‐bis (4‐4‐aminophenoxy) phenyl) hexafluoropropane, by extrusion into various aqueous organic media. Polyimide fibers obtained from polyamic acid fibers after thermal imidization exhibited round or oval cross‐sections, while fibers obtained directly from a polyimide resin had dogbone, C‐shaped, or oval cross‐sections. The effect of polymer inherent viscosity and filament production parameters on the formation of macropores within the filament will be discussed. Tensile properties of fibers, produced under various conditions, are listed and compared. © 1993 John Wiley & Sons, Inc.
Effects of compatibilization on fractionated crystallization of PA6/PP blends
Authors: Ikkala O. T. , Holsti‐Miettinen R. M. , Seppälä J.
Published: April 2003

In polymer blends, the crystallization of the dispersed semicrystalline component depends on the type and distribution of the nucleating heterogeneities and on the level of the dispersion. Either fractionated or coincident crystallization may result. In this study, the effect of compatibilizers on the crystallization of polyamide 6/isotactic polypropylene (PP) blends was investigated. The morphology was controlled with 10 wt % of four different commercial compatibilizers—PPgMAH, EBAgFA, SEBSgMAH, and E‐EA‐GMA—each leading to specific morphology and crystallization behavior. The compatibilized blends show more complex crystallization compared with the corresponding binary blends. In the compatibilized blends, the dispersed PA6 seems to crystallize coincidently with PP, probably due to its small particle size. The crystallization of PP takes place at temperatures above the bulk value at all compositions in blends compatibilized with PPgMAH and blends without the compatibilizer. By contrast, in blends compatibilized with EBAgFA, SEBSgMAH, and E‐EA‐GMA, the crystallization takes place either at PP bulk temperature or over the temperature range of 76–87°C at the cooling rate of 10°C/min. The amount of the shift cannot be explained solely by the size of the PP dispersion. © 1993 John Wiley & Sons, Inc.
Surface modification of poly(ethylene) in an rf downstream remote plasma reactor
Authors: Holländer A. , Behnisch J. , Zimmermann H.
Published: April 2003

Polyethylene (PE) was treated in a remote downstream reactor with oxygen, nitrogen, hydrogen, and mixed gas plasma. The effects of these treatments were investigated by contact angle goniometry and x‐ray photoelectron spectroscopy (XPS). The oxygen plasma treatment allowed a rapid and efficient hydrophilation of the PE, although the samples were placed far outside the main discharge region. In hydrogen plasma treatment, only a small amount of polar functional groups are formed, while the nitrogen plasma results in a surface similar to that in an oxygen plasma treatment. Thirteen percent of oxygen was found by XPS in these samples, while only 3% of nitrogen was present. The mixed oxygen/hydrogen plasma treatment revealed that 0.1% oxygen in the process gas produced a detectable degree of oxidation. By experiments with quenched atomic oxygen, the singlet molecular oxygen (O½Δ) was found to be the major reactive species in the surface reaction in our system. The role and the source of radiation in this reaction is discussed. © 1993 John Wiley & Sons, Inc.
Thermal conductivities of powder‐filled epoxy resins
Authors: Lin F. , Bhatia G. S. , Ford J. D.
Published: April 2003

Effective thermal conductivities of powder‐filled epoxy composites were experimentally obtained using a transient method. Fillers used were aluminum and cupric oxide. Comparisons of these data with published correlations indicate that Agari's model can give better fits. Nielsen's model may also give a good prediction of the shape of particles can be determined and values of parameters A and ϕm are available. An alternative method of dealing with parameter C2 in Agari's model is suggested. © 1993 John Wiley & Sons, Inc.