bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syntheses and properties of pentaerythritol‐containing urethane prepolymers and crosslinked films
Authors: Yang Chin‐Ping , Lee Lung‐Ta 
Published: April 2003

AbstractTwo series of polyhydroxyl urethane‐prepolymers (Pre‐PU) were synthesized from pentaery‐thritol (PETH), toluene diisocyanate (TDI), and polyglycols (PG). One is a single molecular type of PETH‐(TDI‐PG)n‐TDI‐PETH Pre‐PU (S‐Pre‐PU). The other is a mixture of (PETH‐TDI)n‐PETH and S‐Pre‐PU. The Pre‐PU mixed with an equivalent triisocyanate regenerator (Desmodur AP‐Stable, a crosslinking agent) were baked to form the crosslinked PU films. The mechanical properties such as tensile strengths, elongation at break, and viscoelasticities of PG‐modified crosslinked films were studied.
Crystallization of PP in PP/Ni composites and its correlation with tensile properties
Authors: Maiti S. N. , Mahapatro P. K. 
Published: April 2003

AbstractThe effect of nickel (Ni) powder on crystallization of polypropylene (PP) in PP/Ni composites is studied through differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction techniques. Interpretation of crystallization exotherm peaks in terms of nucleation and growth rates of crystallization, crystallite size distribution, and crystallinity indicated differences in the morphology of PP in all the composites. Crystallinity and tensile behavior decreased on nickel addition. There is a good qualitative agreement in the crystallinity determined by X‐ray diffraction and DSC exotherms, and the variation in both cases, with the volume percent of filler is similar. An attempt has been made to correlate the various tensile properties with the crystallization parameters such as the crystallinity and crystallite size distribution.
Preparation of hydrophilic polyethylene foam of open cell type by radiation grafting of acrylic acid
Authors: Kaji Kanako , Hatada Motoyoshi , Yoshizawa Iwao , Kohara Choji , Komai Kuniaki 
Published: April 2003

AbstractHydrophilic polyethylene foam was synthesized by radiation grafting of acrylic acid onto polyethylene foam of open cell type using monomer solution containing Mohr's salt which inhibits homopolymerization of the monomer. The graft foam was easily dyed by cationic dyes and showed excellent moisture regain. The wicking properties were also excellent and were almost the same as those of commercially available PVA foam. The surface resistivity of 1016 ohm of the original foam decreased to 106 ohm and half decay time of surface charge decreased from 8000 s to 1 s by the grafting, indicating that the grafted foam has excellent antistatic properties.
Kinetics for the tensile strength degradation of nylon and kevlar yarns
Authors: Auerbach I. 
Published: April 2003

AbstractThe tensile strength degradation of nylon 66 and Kevlar 29 yarns was studied at elevated temperatures and over a broad range of relative humidities. The degradation rates for nylon are initially slow but increase rapidly, suggesting the depletion of an inhibitor. Kevlar showed no evidence for similar inhibitor action. The effect of relative humidity on degradation can be very large, especially at values in the 90–100% range and at elevated temperatures. Degradation is governed by thermal‐oxidative and moisture‐induced mechanisms. At the very high humidities and elevated temperatures, the moisture‐induced degradation predominates. Rate relationships were developed in which contributions from each mechanism were considered. Calculated degradation from these relationships agrees well with observed degradation over a broad range of temperatures and humidities.
Large scale preparation of melamine‐based superplasticizing admixtures. II. Pilot plant studies
Authors: Dairanieh I. S. , Lahalih S. M. , Absi‐Halabi M. , Dashti A. 
Published: April 2003

AbstractThe standard procedure for preparing sulfonated melamine–formaldehyde (SMF) resins was slightly modified to prepare an effective more concentrated resin. SMF resins were prepared on a 200‐L pilot plant reactor according to the standard, optimized and slightly modified procedures. In all cases, properties of resins prepared were similar to those which were prepared in a small scale equipment. The scaling up from the 10‐ to the 200‐L reactors was based on a constant agitator tip speed.
Cellulose molecular weights determined by viscometry
Authors: Evans Robert , Wallis Adrian F. A. 
Published: April 2003

AbstractThe equation suggested in the standard method SCAN C15:62 for the estimation of the degree of polymerization (DP) of a cellulose sample from its intrinsic viscosity ([η]) in cupriethylenediamine hydroxide (cuene) solution, P0.905 = 0.75 [η]/mL g−1, where P is an indeterminate average DP, is incorrect. Although differences between the experimental results from several laboratories need to be resolved, a tentative replacement (PV = 1.65 [η]) is suggested, based upon the pooled data and a conversion from the intrinsic viscosity of cellulose tricarbanilate (CTC) in tetrahydrofuran (THF) to that of cellulose in cuene. The treatment of statistical errors in Mark–Houwink–Sakurada parameters, and the nonlinearity of the log[η]−log Pv correlation are discussed.
Attenuated total reflectance (ATR) study of polymer blend films
Authors: Popli R. , Dwivedi Anil M. 
Published: April 2003

AbstractVariable angle ATR was used to obtain a compositional depth profile of films cast from the blend solutions. Blend solutions were prepared from a colloid of high molecular weight styrene–acrylate–methacrylic acid copolymer, an alkali‐soluble styrene–acrylic acid resin neutralized with ammonia and a colloid of copolymer of propylene. Films obtained from drying the blend solutions show a nonhomogeneous distribution of three polymers through the film thickness. This inhomogeneity cannot be explained solely on the basis of sedimentation effects due to density differences between three polymers. Experimental results of ATR using germanium and KRS‐5 crystals are compared to provide estimates of the distance over which nonhomogeneous composition occurs.
Investigation on multiphase polymeric systems of poly(vinyl chloride). I. PVC–chlororubber‐20‐gp‐styrene–acrylonitrile (2 : 1) blends
Authors: Singh Y. P. , Singh R. P. 
Published: April 2003

AbstractA graft copolymer [chlororubber‐20‐gp‐styrene–acrylonitrile (2 : 1)] has been synthesized by a solution precipitation polymerization technique grafting styrene and acrylonitrile onto chlororubber‐20 main chain. The graft copolymer has been characterised by elemental analysis, IR spectroscopy, and viscometry. It has been blended with PVC by melt mixing using a Brabender plasticorder and extrusiograph. The mechanical properties such as flexural and tensile strengths and impact strength of the blends have been studied to evaluate its performance as an impact modifier. The behavior of PVC–chlororubber‐20‐gp–styrene‐acrylonitrile (2 : 1) blends has also been compared with PVC–chlororubber‐20 and PVC–KM‐365B (a commercial acrylate modifier) blends. The thermal behavior of these blends has also been studied. It has been found that PVC–chlororubber‐20‐gp‐styrene–acrylonitrile (2 : 1) blends have higher impact strength than PVC–chlororubber‐20‐gp blends though the PVC–KM‐365B blends have the highest impact strength. Based on the authors' previous compatibility studies along with present X‐ray diffraction studies and the morphological investigation of the fractured surface by scanning electron microscopy, the mechanical behavior of these blends have been explained in the framework of existing theories. A model has been proposed to account for the optimum dispersion and adhesion of graft polyblends of chlororubber‐20 in PVC matrix.
Estimation of polymer crystallinity by dynamic mechanical techniques
Authors: Khanna Y. P. 
Published: April 2003

AbstractDynamic mechanical techniques can be used for a rapid estimation of polymer crystallinity with an accuracy of better than ±20%. The advantage of our proposed procedure is that it is absolute and the crystallinity can be instantaneously estimated when the dynamic mechanical analysis (DMA) data is available. A serious limitation is its applicability to crystallizable polymers (e.g., a quenched nylon 6) where higher values are obtained due to crystallization during the DMA experiment. Another limitation is that our technique cannot be applied to as polymerized samples, e.g., powders or pellets; only fabricated products such as films, fibers, or plaques are suitable for this determination using DMA. Using a variety of polymer systems, the underlying principle, advantages, disadvantages, and recommendations on crystallinity evaluation by DMA are presented. At present we consider this method to be more of a different approach rather than value it as a crystallinity measurement technique, especially for quenched polymers.
Photodegradation of rigid PVC formulations. II. Spectral sensitivity to light‐induced yellowing by polychromatic light
Authors: Andrady Anthony L. , Searle Norma D. 
Published: April 2003

AbstractThe wavelength sensitivity of a compounded extruded rigid poly(vinyl chloride) formulation to yellowing under exposure to filtered xenon radiation is determined using a cut‐on filter technique. Spectral sensitivity of the formulation in the absence and the presence of 2.5 phr of rutile titanium dioxide was examined, and the results were compared to those previously reported for the yellowing of an identical vinyl formulation exposed to monochromatic light. Maximum in the activated spectrum for yellowing under exposure to filtered xenon radiation was found to be in the wavelength region 300–320 nm for both types of samples. The results agreed qualitatively with those previously obtained in the study of the same material exposed to monochromatic light.
Interaction of dyes with chitosan derivatives
Authors: Seo Toshihiro , Hagura Shigeki , Kanbara Takaki , Iijima Toshiro 
Published: April 2003

AbstractThe states of water in N‐acylated, both aliphatic and aromatic, chitosan gels were investigated by DSC technique. The amounts of two states of water, freezable and nonfreezable water, were found to depend on the chemical and physical structure of the gels. The interaction between these hydrophobic gels and the dyes which have been designed and prepared to carry the ionic, hydrophilic, and hydrophobic nature was determined in detail. The dyes having OH, N(C4H9)2, and naphthalene nucleus show a remarkable increase of the equilibrium sorption to compare with that of methyl orange. The contribution of the electrostatic, hydrophobic, and hydrogen bonding interaction in the sorption was discussed. The predominant contribution of the hydrophobic interaction in the systems of butyl orange/N‐octanoyl chitosan gels has been made clear by means of the temperature dependence of the sorption.
Fatigue fracture of reaction injection molded (RIM) nylon composites
Authors: Martin D. C. , Novak G. E. , Wyzgoski M. G. 
Published: April 2003

AbstractThis study was undertaken to determine how milled glass fibers affect the fatigue resistance of reaction injection molded (RIM) nylon 6. Specifically the effects of glass content, fiber length, orientation, and surface treatment were investigated. The fatigue crack growth rates for unfilled and glass‐filled samples were observed to follow the well‐known Paris equation in terms of dependence on cyclic stress intensity factor. For the unfilled nylon a line shaped zone was observed in advance of the crack tip. Fractography results suggest that the zone was the projection of the actual crack tip profile through the thickness of the sample rather than a distinct plastic or deformation zone. The fatigue fracture surface exhibited a patchy type structure with features 50–150 μm in size, suggesting a void coalescence type of mechanism as has been reported for injection molded nylons. A diffuse damage zone, several millimeters in size, was observed at the crack tip for the glass‐filled RIM nylon 6. The zone was observed to pulsate with the applied oscillating load. The growth of the damage zone volume with increasing crack length (and thus increasing stress intensity factor range) followed the Paris law, as did the crack growth rate data. The damage mechanism is attributed to void formation and microcracking at the fiber–matrix interface. The results of this study show that, for milled glass‐reinforced RIM nylon 6, the crack growth rates were much more rapid than observed for injection‐molded nylon 6 containing chopped glass fibers. This difference is attributed to the greatly reduced glass fiber lengths for the milled glasses.
A kinetic study of benzoyl peroxide decomposition in graft copolymerization bath
Authors: Sójka‐Ledakowicz J. , Ledakowicz S. 
Published: April 2003

AbstractThe rates of decomposition of benzoyl peroxide have been studied in water alone and in the presence of the components of graft copolymerization bath, viz. diphenyl and acrylic acid, in the temperature range of 363–403 K. Kinetic parameters such as reaction order for the peroxide, preexponential factor, and activation energy were evaluated from experimental data. The implication of these results to the initiation of graft copolymerization of acrylic acid onto polyester fabrics is discussed.
ESR and DSC study of the radiation crosslinking effect on macroradical decay in poly(vinylidene fluoride)
Authors: Klimová M. , Szöcs F. , Bartoš J. , Vacek K. , Pallanová M. 
Published: April 2003

AbstractThe decay of polyenyl macroradicals in irradiated poly(vinylidene flouride) and its dependence on radiation crosslinking was studied by the ESR method. The decay rate constants were found to decrease in the lower temperatures region but they show some anomaly at higher temperatures with respect to radiation dose. Temperature dependences of kinetic constants are correlated with thermodynamic parameters from DSC measurements and are interpreted as a result of the steric hindrances changes on molecular mobility due to structural changes caused by radiation crosslinkings and phase transition in a semicrystalline matrix.
Measurement of diffusion of antioxidants in isotactic polypropylene by isothermal differential thermal analysis
Authors: Schwarz T. , Steiner G. , Koppelmann J. 
Published: April 2003

AbstractThe diffusion of the phenolic antioxidant 1,3,5‐tris(3,5‐di tert‐butyl‐4‐hydroxybenzyl)mesitylene (IRGANOX 1330) in extruded sheets of isotactic polypropylene (iPP) was investigated over the temperature range from 80 to 120°C by isothermal differential thermal analysis (DTA). The measurements showed a clear relation between oxidation induction time and oxidation maximum time (both determined by isothermal DTA) and the concentration of stabilizer. It was possible to calculate the diffusion coefficients and the activation energy of diffusion of IRGANOX 1330 in iPP by measuring the oxidation maximum times across stacks of isotactic polypropylene sheets.
Crosslinking structure of keratin. II. Intermolecular and intramolecular crosslinks in potassium‐cyanide‐treated wool fibers
Authors: Arai Kozo , Sakamoto Munenori , Naito Sachio , Takahashi Toshie 
Published: April 2003

AbstractThe crosslinking structure of keratin fibers has been investigated. The reaction of wool with aqueous KCN was studied by means of chemical and physical methods. Quantitative conversion of disulfide (SS) groups of the cystine (Cys) residues into stable thioether (S) linkages was confirmed. In terms of mechanically effective and noneffective crosslinkages, the amounts of intermolecular and intramolecular crosslinks in the KCN‐treated wools were determined from the analysis of the corresponding amino acids and mechanical experiment in which the shear modulus of swollen, rubberlike samples is determined from the relation between equilibrium stress and strain for simple extension of the fiber in a diluent. A modified elastic equation of state was used for the calculation of the number of intermolecular crosslinks. The front factor in the equation used was determined by combining the results obtained from purely chemical kinetics and the values of shear modulus of the swollen wools. The ratio of the number of intermolecular and intramolecular SS crosslinkages in the Lincoln wool, was found to be 64:36. The reactivity of the former is much higher than that of the latter, and these two types of SS crosslinks form substantially the same type of S crosslinks. The fraction of the Cys residues accessible to cyanideions depends mainly on the reaction temperature.
Separation of poly(styrene–methyl methacrylate) block copolymers by liquid adsorption chromatography
Authors: Mori Sadao 
Published: April 2003

AbstractBlock copolymers P(S‐b‐MMA) prepared by using polymeric peroxide as an initiator were separated into three peaks using silica gel as an adsorbent and a mixture of chloroform and ethanol as the mobile phase. The first peak included both polystyrene homopolymer and P(S‐b‐MMA), the second peak appeared to be P(S‐b‐MMA), and the third consisted of P(S‐b‐MMA) and poly(methyl methacrylate) homopolymer. These results suggest the presence of three different block copolymers in composition and/or in structure. By removing the two homopolymers, it was found that the P(S‐b‐MMA) sample prepared in this work consisted of two components of equal amount: One was a block copolymer having a smaller MMA content and smaller molecular weight averages and the other having a higher MMA content (similar to the monomer feed ratio) and higher molecular weight. Besides these two components, one minor copolymer, which might be different from these two components but rather similar to the first one in both composition and molecular weight, appeared between these two peaks in a liquid adsorption chromatogram. These three components had both composition and molecular weight distributions.
Dielectric properties of halar, an alternating copolymer of ethylene and chlorotrifluoroethylene
Authors: Khanna Y. P. , Taylor T. J. , Chandrasekaran S. 
Published: April 2003

AbstractDielectric properties of Halar, a predominantly alternating 1 : 1 copolymer of ethylene (E) and chlorotrifluoroethylene (CTFE), have been obtained as a function of temperature (−100 to +175°C), frequency (102–106 Hz), and thermal history. The dielectric loss index (ε″), related to heat dissipation in electrical applications, shows no major change between 25 and 175°C. However, a significant increase in (ε″) between +25°C and −100°C is not considered detrimental for the applications. Activation energies (δE) for the three major relaxations (α‐, β‐, and γ‐) in both mechanical and dielectric experiments are similar, thus suggesting a similar phase origin of the molecular relaxations in the two techniques. In dielectric analysis, the lowest temperature γ‐relaxation is the strongest while it is the weakest in mechanical technique. It is proposed that, in dielectric experiments, only the CTFE groups participate and due to restricted mobility at low temperatures (i.e., γ‐relaxation), the dissipation factor or relaxation strength is maximum.
Test methodology for the determination of optimum fusion welding conditions of polyethylene
Authors: Saint‐Royre D. , Gueugnaut D. , Reveret D. 
Published: April 2003

AbstractThe fusion welding behavior of a medium density polyethylene resin has been studied for a wide range of heating rates using a recently developed test methodology. With this method, the thermal and physical phenomena occurring at the interface of two thin polyethylene pieces assembled by fusion can be studied. It consists of a thermal welding phase and a phase of mechanical separation of the welded assembly. For the mechanical phase, an adaptation of the T‐peel test was used. These conditions make it possible to determine the thermal welding parameters (temperature, time) for optimal mechanical quality of the joint, according to a criterion established by optimization of the peel test used. The variations in minimum temperature required for an optimum weld, as a function of heating rate, can be simulated with a numerical model based on the concept of macromolecular interdiffusion. Consistent with the experimental behavior, the numerical model involves two parameters characteristic of the diffusion behavior of the polyethylene resin. Thus, these parameters characterize the weldability of the polyethylene resin under study.
Insoluble poly(akylarylphosphine)siloxanes and their application as supports for catalytic transition‐metal complexes
Authors: Ejike E. N. , Parish R. V. , Jideonwo A. 
Published: April 2003

AbstractLight induced addition of diphenylphosphine (DPP) to methylvinylcyclotetrasiloxane (MVS) yielded poly(2‐diphenylphosphinoethyl) cyclotetrasiloxane (DPPS). Similar treatment of allyldiphenylphosphine (ADPP) with linear poly(methylhydrogenosiloxane)‐co‐hexamethyldisiloxane (PMS) led to formation of poly(3‐diphenylphosphinopropyl)methylsiloxane‐co‐hexamethyldisiloxane (PPMS). DPPS and PPMS were condensed by acid treatment to give insoluble rubbery phosphine bearing materials P1 and P2, respectively. Iridium and rhodium complexes were immobilized on P1 and P2. The ability of a high molecular weight substrate (PMS) to migrate to active catalytic centers within support matrix was examined. The effect of varying metal: phosphine ratio and total percentage metal on the support were examined during catalysis of O‐silylation of ethanol with PMS and triethoxysilane (TES).
Laminar and turbulent flow continuous interfacial polycondensations of nylon 66
Authors: Griskey Richard G. , Patel C. A. 
Published: April 2003

AbstractThe interfacial polycondensations of nylon 66 in a continuous reaction system have been studied. An experimental stirred flow reactor was used to determine both yield and intrinsic viscosity (molecular weight) as functions of reactant ratio (adipoyl chloride/hexamethylene‐diamine), and Reynolds number from laminar to turbulent flow. It was found that mass transfer was the controlling factor in the reaction system. The yield as a function of Reynolds number was found to directly correlate with the behavior of the combination of mass transfer coefficient and interfacial area. Intrinsic viscosity had maximum values in the same reactant ratio range as for batch and continuous cascade systems studied earlier. Intrinsic viscosity behavior was shown to relate to interfacial area behavior.
Thermoplastic composties of polystyrene: Effect of different wood species on mechanical properties
Authors: Maldas D. , Kokta B. V. , Daneault C. 
Published: April 2003

AbstractBoth softwood (spruce) and hardwood (aspen and birch) species in the form of different pulps (e.g., sawdust, chemithermomechanical pulp, explosion pulp and OPCO pulp) have been used (10–40 wt% composite) as reinforcing fillers for thermoplastic composites of polystyrene. Mechanical properties, are examined, e.g., tensile modulus, tensile strength at maximum point, and the corresponding elongation and energy as well as impact strength of compression molded composites. To improve the compatability of wood fibers which are hydrophilic and the polymer matrix which is hydrophobic, poly[methylene(polyphenyl isoeyanate)] (2 and 8 wt % of polymer) was used as a coupling agent. The mechanical properties of the treated composites are improved up to 30% in fiber content whereas a downward trend for untreated composites was observed when an increase in fiber content occurred. The overall improvements in mechanical properties due to the addition of isocyanate can be explained by the linkage of isocyanate molecules with fiber matrix through the chain of covalent bonds and the interaction of π‐electrons of benzene rings of polystyrene as well as isocyanate. As a result, poly[methylene(polyphenyl isocyanate)] forms a bridge between fiber and polymer on the interfaces. This result is instrumental for efficient stress transfer between cellulose fibers and thermoplastics. The performance of different pulps of various wood species as reinforcing fillers for thermoplastic composites is also examined.