bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence of irradiation‐induced crosslinking in miscible blends of poly(vinyl chloride)/epoxidized natural rubber in presence of trimethylolpropane triacrylate
Authors: Ratnam Chantara Thevy , Nasir M. , Baharin A. , Zaman Khairul
Published: October 2004

Electron‐beam initiated crosslinking of a poly(vinyl chloride)/epoxidized natural rubber blend (PVC/ENR), which contained trimethylolpropane triacrylate (TMPTA), was carried out over a range of irradiation doses (20–200 kGy) and concentrations of TMPTA (1–5 phr). The gelation dose was determined by a method proposed by Charlesby. It was evident from the gelation dose, resilience, hysteresis, glass‐transition temperature (Tg), IR spectroscopy, and scanning electron microscopy studies that the miscible PVC/ENR blend underwent crosslinking by electron‐beam irradiation. The acceleration of crosslinking by the TMPTA was further confirmed in this study. Agreement of the results with a theory relating the Tg with the distance between crosslinks provided further evidence of irradiation‐induced crosslinking. The possible mechanism of crosslinking induced by the irradiation between PVC and ENR is also proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1914–1925, 2001
Effect of hydrogen donor on the thermal degradation of poly(vinyl acetate) in solution
Authors: Madras Giridhar , Chattopadhyay Sujay
Published: October 2004

The thermal decomposition of poly(vinyl acetate) (PVAc) in solution was investigated both in the presence and absence of a hydrogen donor (H‐donor). Thermal degradation experiments at 220–250°C were conducted in a batch reactor by dissolving PVAc in diphenylether. The molecular weight distributions were measured as a function of reaction time. Experimental data indicated that the polymer degrades by random chain scission. The random scission degradation rate coefficient was between 9.01 × 10−4 and 6.12 × 10−3 min−1. The activation energy, determined from the temperature dependence of the rate coefficient, was 31.5 kcal/mol. The effect of an H‐donor, diphenylamine, was also investigated by varying the concentration from 0 to 0.472 mol/L. The data indicated that the presence of diphenylamine increases the PVAc degradation rate from 3.67 × 10−3 to 4.59 × 10−3 min−1 at 240°C. This is in contrast to the reduction in the degradation rate of polystyrene in the presence of diphenylamine. Continuous distribution models have been developed by treating molecular weight as a continuous variable. The experimentally observed variation of the degradation rates with H‐donor concentration is satisfactorily explained by a continuous distribution model based on the radical mechanism that involves the elementary reactions including the hydrogen abstraction steps. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1996–2000, 2001
Synthesis and characterization of polymers derived from selenophene
Authors: Del Valle M. A. , Moreno J. , Díaz F. R. , Tagle L. H. , Bernède J. C. , Tregoüet Y.
Published: October 2004

The synthesis of poly(2,5‐selenophen‐oxo‐1,4‐phenylen‐selenide‐1,4‐phenylene‐oxo) (I) and poly(2,5‐selenophen‐oxo‐1,4‐phenylen‐diselenide‐1,4‐phenylen‐oxo) (II) by reaction of 2,5‐bis(1,4‐bromo‐phenylen‐oxo‐)‐selenophene with sodium selenide or diselenide, respectively, using dimethylformamide as solvent, is described. Both monomers and polymers were characterized by elemental analysis, melting point, and FTIR spectroscopy. Polymers I and II were doped with iodine and SbF5 and characterized by SEM and XPS. Also, the conductivity and the Tg values were determined. For both polymers the best doping agent was iodine, although polymer II always presented higher conductivity, reaching values of about 6 · 10−9 S · cm−1. The Tg values suggest a likely crosslinking of the chains in polymer II when doped with SbF5. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2019–2026, 2001
Dynamic‐mechanical study of water‐blown rigid polyurethane foams with and without soy flour
Authors: Chang Li‐Chung , Xue Yu , Hsieh Fu‐Hung
Published: October 2004

Glass transition temperatures of water‐blown rigid polyurethane foams at three levels of initial water content, 4.5–5.5%, and five levels of soy flour, 0–40%, were determined by dynamic‐mechanical instrumentation at the temperature range of 50–280°C and the frequencies from 0.1 to 20 Hz. The results showed that both the addition of soy flour in the rigid polyurethane foam system and increasing initial water content contributed to a higher glass transition temperature. Moreover, increasing the percentage of the soy flour in the rigid polyurethane foam system led to higher compressive strength and broader master curves for the imaginary part of the elastic modulus. The KWW function fitted the master curve better than the HN and CD functions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2027–2035, 2001
Kinetics of NMBA polymerization in a starved feed reactor
Authors: Cao Gui‐Ping , Zhu Zhong‐Nan , Zhang Ming‐Hua , Le Hui‐Hui , Yuan Wei‐Kang
Published: October 2004

A starved feed reactor (SFR) is a semibatch polymerization reactor in which initiator and monomer are fed slowly into a fixed amount of solvent. The polymerization is carried out isothermally at elevated temperatures. The added initiator decomposes instantaneously, and the added monomer polymerizes immediately. The monomer concentration in the SFR is very low, ideally approaching zero. The reactor is in a starved status for reactants. The molecular weight of the product polymer can be effectively controlled by the feed ratio of monomer to initiator. This article presents a study on the kinetics of NBMA polymerization in an SFR. The model parameters were regressed with the experimental data. Although the mass fraction of polymer in the SFR was high (higher than 50%), viscosity was not high and the “gel effect” was weak because of the low molecular weight of the products. It was found that the termination rate constant is a power function of polymer concentration, and the lumped rate constant, kp/(k)1/2, can be modeled by the Arrhenius equation. The initiator efficiency, f, remained constant at a temperature less than 120°C, and increased with the temperature increasing at temperatures greater 120°C. The other parameters remained constant in the experiment range. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2068–2075, 2001
Semi‐interpenetrating polymer networks from castor oil‐based polyurethane and nitrokonjac glucomannan
Authors: Gao Shanjun , Zhang Lina
Published: October 2004

New semi‐interpenetrating polymer networks (semi‐IPNs) coded as PUNK were successfully synthesized from castor oil‐based polyurethane (PU) prepolymer and 10–40 wt % nitrokonjac glucomannan (NKGM) containing a degree of substitution of 2.4 and a weight‐average molecular weight of 4.75 × 104. The semi‐IPN sheets that were 100 μm thick were cured more speedily than PU, with curing times of 5 h for PUNK and 16 h for PU at 50–70°C. The structure and miscibility of the semi‐IPN sheets were studied by Fourier transform infrared spectroscopy, ultraviolet spectroscopy, and scanning electron microscopy. The results showed that a strong intermolecular interaction caused by hydrogen bonding between NKGM and PU exists in PUNK, resulting in good miscibility. When the NKGM content of the semi‐IPNs sheets was 20 wt %, the tensile strength and light transmittance were obviously higher than that of the PU sheets. The NKGM in the semi‐IPN sheets plays an important role not only in accelerating the cure but also in improving the mechanical properties and biodegradability. As a new material prepared from renewable resources, PUNK has potential applications because of its biodegradability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2076–2083, 2001
The use of positron annihilation lifetime technique to study the effect of doping metal salts on polyhydroxamic acid polymers
Authors: Mazzroua A. , Mostafa N. , Gomaa E. , Mohsen M.
Published: October 2004

Polyhydroxamic acid (PHA) from polymethacrylamide (PMAA) was prepared. Chromium chloride (CrCl3) and ferric chloride (FeCl3) salts were added to the polymer in order to increase its electrical conductivity, i.e., the dopants help produce semiconducting properties. The positron annihilation lifetime technique spectroscopy (PALS) was used to study the changes in the free volume as a function of FeCl3 and CrCl3 concentrations. ortho‐Positronium lifetime components were used to estimate the free volume parameters. It was found that the hole size and the total free volume fraction decreased with FeCl3 concentration. On the other hand, the hole size increased slightly with CrCl3 concentration and then decreased, while the total free volume fraction increased continuously. The free volume distributions were determined from ortho‐positronium distributions. The electric conductivity as a function of FeCl3 and CrCl3 concentrations showed fluctuation behavior and showed a continuous increase with the increase in temperature. The correlation between positron annihilation parameters and electric conductivity were discussed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2095–2101, 2001
Depolymerization of polyethyleneterephthalate in supercritical methanol
Authors: Kim B.‐K. , Hwang G.‐C. , Bae S.‐Y. , Yi S.‐C. , Kumazawa H.
Published: October 2004

The depolymerization of polyethyleneterephthalate (PET) in supercritical methanol was carried out using a batch‐type autoclave reactor. The total conversion and the yield of dimethylterephthalate (DMT) increased with rising temperature. The final yield of DMT at 300°C and 310°C reached 97.0% and 97.7%, respectively. The yield of DMT was markedly increased when the methanol density was 0.08 g/cm3, and leveled off at higher densities. A kinetic model to describe the depolymerization of PET in supercritical methanol was proposed, where the scission of one ester linkage in PET by a methanol molecule produces one carboxymethyl group and one hydroxyl group. The values of the forward reaction rate constant at different temperatures were determined by comparing the observed time dependence of carboxymethyl group concentration with that calculated by the proposed model. The activation energy was evaluated to be 49.9 kJ/mol, a value close to a literature value (55.7 kJ/mol). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2102–2108, 2001
Release of model compounds from modified lactone copolymers
Authors: Karjalainen Teija , Rich Jaana , Seppälä Jukka
Published: October 2004

The applicability of three different P(ϵ‐caprolactone‐co‐DL‐lactide) copolymers for injection‐molded controlled release devices was evaluated. The copolymers of ϵ‐caprolactone and DL‐lactide were polymerized in bulk using Sn(II) octoate as the catalyst. Glycerol, polyethylene glycol 1000, and polyethylene glycol 4000 were used as initiators. Copolymers were characterized by size exclusion chromatography, differential scanning calorimetry, and nuclear magnetic resonance spectroscopy measurements. The release of two model compounds, theophylline and propranolol hydrochloride, at different loadings (2–30 wt %) was studied. The solubility of the model compounds into the matrices was confirmed to be low by DSC measurements. Increasing the hydrophilicity of the copolymer matrix increased the release rates of both model compounds. The results clearly demonstrate that the desired release rates of these model compounds can be tailored by varying the compound loading or modifying the hydrophilicity of the matrix copolymer. The copolymers were found to be relatively stable during the 4‐month hydrolysis. Addition of hydrophilic polyethylene glycol blocks into the backbone of the copolymer chain increased water absorption and thus the degradation was faster. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2118–2126, 2001
Synthesis and properties of poly(butylene succinate) with N‐hexenyl side branches
Authors: Jin Hyoung‐Joon , Kim Duck‐Soo , Kim Mal‐Nam , Lee Ick‐Mo , Lee Han‐Sup , Yoon Jin‐San
Published: October 2004

N‐hexenyl side branches were introduced into poly(butylene succinate) (PBS) by polymerization of succinic acid (SA) with 1,4‐butanediol (BD) in the presence of 7‐octene‐1,2‐diol (OD). Thermal properties and biodegradability of the aliphatic polyesters were investigated before and after epoxidation of the pendant double bonds. The glass‐transition temperature (Tg) decreased with the branching density to give a minimum at 0.03 mol of branching units per mole of structural units. Thereafter, Tg increased due to the in situ crosslinking of the unsaturated groups during the differential scanning calorimetry (DSC) measurements. N‐Hexenyl side branches decreased melting temperature (Tm) more significantly than ethyl side branches, but the effect was on par with that by n‐octyl branches. Epoxidation of the double bonds decreased Tm and melting enthalpy (ΔHm), but increased Tg of the aliphatic polyester. Biodegradability was enhanced to some extent by the presence of n‐hexenyl side branches. However, the epoxidation of the unsaturated groups did not notably affect the biodegradability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2219–2226, 2001
Miscibility behavior of metallocene polyethylene blends
Authors: Chen Fei , Shanks Robert , Amarasinghe Gandara
Published: October 2004

Very‐low‐density polyethylenes (VLDPEs) with short branches, formed by metallocene or Ziegler–Natta catalysts, were blended with low‐density polyethylenes (LDPEs) or VLDPEs with long branches. The crystallization and melting behavior of these blends were examined by differential scanning calorimetry (DSC). The blends of metallocene‐catalyzed VLDPE1 and LDPEs showed a smooth change in both crystallization and melting peak temperatures, indicating that there was co‐crystallization and, hence, partial miscibility at all compositions. However, the blends of VLDPE1 and long‐chain branched VLDPE2 co‐crystallized at 50% or less VLDPE2 content, whereas Ziegler–Natta‐catalyzed VLDPE3–VLDPE2 blends showed co‐crystallization at 50% or higher VLDPE2 compositions. It is concluded that either complete or partial miscibility has occurred between the two polyethylenes in each of the blends with VLDPE2. Nevertheless, VLDPE2 did not cause a significant change in the morphology of VLDPE1, perhaps because of the reduced number of long branches present in VLDPE2 compared with LDPEs. The molar masses or melt flow indices of the polyethylenes were not significant in controlling the morphology; only the distribution of branches along the chains was important. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2227–2236, 2001
Effects of moisture on properties of epoxy molding compounds
Authors: Lu M. G. , Shim M. J. , Kim S. W.
Published: October 2004

In this article the effects of moisture on a novel epoxy molding compound, including the mechanical properties, temperature transition, and thermal degradation behavior, are studied. The experimental results reveal that the absorbed water acts predominantly as a crazing agent, continuously decreasing the mechanical strength with the time in water. The glass‐transition temperature decreases at the early stage and is finally equilibrated. The thermal degradation behavior of the materials is not greatly influenced by the hydrothermal age. The decomposition of samples in oxygen is composed of two independent steps: the thermal degradation and oxidation at high temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2253–2259, 2001
Degradation of the mechanical properties of composite vulcanizates loaded with paraffin wax
Authors: Abu‐Abdeen M.
Published: October 2004

A composite of Styrene Butadiene Rubber (SBR) and Natural Rubber (NR) loaded with 40 phr of High Abrasion Furnace (HAF) carbon black is loaded with different concentrations of paraffin wax. From the stress–strain curves, Young's modulus was found to decrease with increasing the amount of added paraffin wax. The modified Mooney‐Revlin equation was used to calculate the parameters C1 and C2. A plot between the true tensile stress as a function of (λ2 − λ−1) was used to calculate two parameters σ0 and G, and then both the average molecular weight between crosslinks and the number of effective plastic chains per unit volume were also calculated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2265–2270, 2001
Effect of heat treatment on the structural and conformational changes of regenerated Antheraea pernyi silk fibroin films
Authors: Kweon Haeyong , Woo Soon Ok , Park Young Hwan
Published: October 2004

Regenerated Antheraea pernyi silk fibroin films prepared from calcium nitrate solution were treated with heat for crystallization. The structural and conformational changes caused by heat treatment were investigated with X‐ray diffraction, infrared spectroscopy, and differential scanning calorimetry. The temperature and treatment time of heat greatly influenced the conformation of the regenerated films. The conformational change was caused by heat treatment over 230°C, and the transition was enhanced by increasing time and temperature. The contents of α‐helix, β‐sheet, and random‐coil conformations were calculated and examined to investigate the effect of heat treatment on the conformational changes. The β‐sheet structure could be transformed from a random‐coil conformation on heat treatment, whereas the content of α‐helix structure was nearly unchanged, regardless of heat‐treatment conditions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2271–2276, 2001
Investigation into the rheological properties of PES/NMP/nonsolvent membrane‐forming systems
Authors: Li Zhansheng , Jiang Chengzhang
Published: October 2004

From the perspective of a polymer solution, the rheological properties of the popular polyethersulfone (PES)/N‐methyl‐2‐pyrrolidone (NMP)/nonsolvent (NS) membrane‐forming system were investigated thoroughly with a controlled stress rheometer (HAAKE RS75, Germany). The scope of the study included measurements of the controlled‐stress flow curve, creep recovery, and dynamic oscillation. H2O, 1‐butanol, ethylene glycol, and diethylene glycol were used as NS additives. The effects of the polymer concentration and the quality of the solvent mixture, as characterized by the approaching ratio, on the rheological behavior of the dopes were studied. Up to 38 wt % PES and extremely adjacent to the phase separation (i.e., the approaching ratio of the dope was 0.95), the viscous property dominated all the dopes, which behaved as Newtonian fluids. Moreover, all the membrane‐forming dopes investigated were in the crossover regime in the semidilute region, in which the chains were overlapping but unentangled. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 283–291, 2001
Dextran–rare earth ion interactions. I. Dynamics in aqueous solutions
Authors: Mazi H. , Zümreoğlu‐Karan B. , Güner A.
Published: October 2004

The interaction of light‐lanthanoid cations (La3+, Ce3+, and Nd3+) with dextran in aqueous solutions was studied by viscosimetric, turbidimetric, and conductimetric methods. The effects of the type of the cation and the concentration of the cation on the interaction mechanism were investigated. Viscosity behavior of the solutions was interpreted using the Huggins and Kraemer equations; intrinsic viscosities and the slopes were calculated. The results found from the Huggins and Kraemer approaches accorded well. The order of interaction was determined as La3+ > Ce3+ > Nd3+. In all experimental methods applied, a critical concentration of the Ln3+ ion (≈0.08 mol Ln3+/L) was noted at which the observed property showed a significant change. Up to this critical concentration, viscosities of the dextran/Ln3+ solutions decreased and after making an outstanding turn at this point increased toward higher concentrations. Turbidimetric and precipitation experiments gave opposite results as expected but the same order for the cation and the same value of critical concentration. The results obtained from the application of a mathematical model to the precipitation data verified the conclusions attained by viscosimetry and conductimetry. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 323–329, 2001
Nonisothermal crystallization of isotactic polypropylene blended with poly(α‐pinene). I. Bulk crystallization
Authors: Di Lorenzo Maria Laura , Cimmino Sossio , Silvestre Clara
Published: October 2004

The influence of a natural terpene resin, poly(α‐pinene) (PαP), on the nonisothermal crystallization process of isotactic polypropylene (iPP) was investigated. The solidification process strongly depends on cooling rate, composition, and miscibility of the system. For the blends containing PαP up to 30 wt %, the overall nonisothermal crystallization rate is depressed with respect to plain iPP. This is probably the result of the diluting effect of the polyterpene because the two components are miscible. The 50/50 blend presents, instead, two amorphous phases: an iPP‐rich phase and a PαP‐rich phase. For this composition, solidification starts at temperatures higher than those for plain iPP and blends with lower PαP content, given that the diluting effect of PαP in the iPP‐rich phase is counterweighted by an increased number of nuclei that originate from the polyterpene‐rich phase domains. PαP also influences the morphology of iPP spherulites, which are spherical in plain iPP and become more irregular with increasing PαP content. The number and dimension of iPP spherulites depend on blend composition and miscibility of the components. Moreover, the nonisothermal crystallization kinetics of iPP/PαP blends was analyzed with the Ozawa equation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 358–367, 2001
Studies on SLS doped polyaniline and its blend with PC
Authors: Jeevananda T. , Siddaramaiah  , Annadurai V. , Somashekar R.
Published: October 2004

Electrically conductive polyaniline (PANI) and its blend with polycarbonate (PC) was prepared by one‐step emulsion polymerization technique in which sodium lauryl sulfate (SLS) acts as surfactant and as a protonating agent for the resulting polymer. The prepared PANI and its blends were characterized by density, percentage of water absorption, and electrical conductivity. PANI–PC blend exhibits a conductivity value of 4.70 × 10−2 S/cm (PANI–PC1) and 5.68 × 10−5 S/cm (PANI–PC3) with a change in dopant from p‐toluene sulfonic acid (TSA) to SLS, respectively. By using a more general method, which takes into account the presence of disorder of the second kind in polymers proposed by Hosemann, crystal size (〈N〉) and lattice strain (g in %) values were estimated. The variation of conductivity in doped PANI and PANI–PC blend has been explained on the basis of these microcrystalline parameters. TGA thermograms of PANI and PANI‐PC blend show three‐step degradation behavior. Thermal stability of PANI was improved after blending with PC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 383–388, 2001
Surface modification of LDPE film by chemical processes with Ni2+ and ammonium persulfate
Authors: Bandopadhay D. , Panda A. B. , Pramanik P.
Published: October 2004

Chemical modification of the surface of low‐density polyethylene (LDPE) film was performed with an aqueous solution of ammoniacal ammonium persulfate in the presence of Ni2+ ions, where the polar groups were generated on the surface of the LDPE film. The surface of the LDPE film was modified chemically with an ammoniacal solution of ammonium persulfate (1.1M) and Ni(SO4)2 (0.02M) heated at about 70°C for 3 h. The morphologies of the surfaces were studied with scanning electron microscopy and infrared spectroscopy; electron spectroscopy for chemical analysis revealed the introduction of polar groups on the surface, which improved printability and adhesion properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 406–415, 2001
Polypropylene/polystyrene blends—Preliminary studies for compatibilization by aromatic‐grafted polypropylene
Authors: Mustafa S. J. Syed , Nor Azlan M. R. , Ahmad Fuad M. Y. , Mohd Ishak Z. A. , Ishiaku U. S.
Published: October 2004

The blends of Polypropylene (PP), that is a semicrystalline and nonpolar thermoplastic polymer with a polar and amorphous polymer such as Polystyrene (PS), are known to be immiscible. This article investigates the use of an aromatic vinyl monomer (AVM)‐grafted PP (PPA) as a potential compatibilizer for such an immiscible blend system (PP/PS blend). PPA was prepared by grafting a monofunctional aromatic vinyl monomer onto PP using an organic peroxide at 180°C for 10 min in a Brabender mixer. Using a twin‐screw extruder, blends of PP/PS in various composition containing different amount of PPA were prepared. Results obtained from tensile and impact strength, heat deflection, and melt flow index measurements shows some improvement in the properties of the blends indicating some compatibilization effects in the blend system. However, the scanning electron microscopy (SEM) micrographs strongly suggested a significant compatibilization between PP and PS. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 428–434, 2001
Synthesis and in situ transformation of poly(oxybutylene)amides by butoxylation
Authors: Lin Jiang‐Jen , Wu Jeng‐Jaw , Ho Yung‐Sheng
Published: October 2004

A family of gasoline detergents was prepared by a two‐step process—(1) preparation of amide initiators by reacting hydrophilic amines with ethyl acetate at high temperature; (2) consecutive butoxylation of the initiators with 1,2‐epoxybutane (BO) to obtain oil‐soluble products. The process led to the preparation of amide‐initiated butoxylates, which were characterized by FTIR, NMR, and amine titration. During the butoxylation, it was found that the unexpected ester by‐products were generated via an amide/ester exchange. The reaction profile was studied. The amide/ester exchange reaction, characterized by IR absorption of amide (1650 cm−1) vs. ester (1735 cm−1), reached equilibrium during the process of butoxylation to 1600 Mw. Steric hindrance of the amide structures is an important factor controlling the formation of these ester byproducts. Selective hydrolysis to remove the ester by‐products is necessary to render the final product with an improved engine performance of octane requirement. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 435–445, 2001
FEG–ESEM investigation of micromechanical deformation processes in ultrafine monospherical SiO2 particle‐filled polymer composites
Authors: Kim G.‐M. , Lee D.‐H.
Published: October 2004

Micromechanical deformation processes responsible for toughening mechanisms in ultrafine monospherical inorganic particle‐filled polyethylene were investigated in situ by a field‐emission gun‐environmental scanning electron microscope (FEG–ESEM) with low‐voltage techniques. In general, the ultimate properties of polymer composites are largely dependent on the degree of dispersion of filler particles into the matrix. Very often, the agglomeration is one of inevitable occurrences in polymer composites, mixed with ultrafine filler particles. In the present work, the effects of agglomerates, consisting of ultrafine monospherical filler particles, were reexamined in polymer composites on the toughening mechanism. The results show that the dominant micromechanical deformation processes are the multiple debonding processes inside agglomerates, in which the ratio of the matrix strand and the size of agglomerate plays a great role of matrix yielding. In the specimen, where the agglomerates are isolated in the matrix, deformation begins at the equatorial region of agglomerates and propagates through them. However, in the case of closely placed agglomerates, deformation occurs homogeneously within the whole area inside the agglomerates. In both cases, in conjunction with the multiple debonding processes, the major part of energy during the deformation dissipates through the shear‐flow processes of the matrix material. In particular, the micromechanical deformation processes observed in this work confirm that the agglomerates do not always have negative effects on the mechanical properties—at least, in the shear deformable semicrystalline polymer matrices. The agglomerates may be effectively used for the improvement of toughness. Furthermore, the FEG–ESEM with low‐voltage techniques offers an extremely promising and efficient alternative method to study the morphology as well as in situ micromechanical deformation processes in nonconducting polymer systems. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 785–789, 2001
Preparation and properties of functionalized polyorganosiloxanes
Authors: Yahaya G. O. , Brisdon B. J. , Maxwell M. , England R.
Published: October 2004

A series of linear functionalized polyorganosiloxanes of the type Me3SiO[MeSiO(CH2)nR]x(Me2SiO)ySiMe3, where n = 2, R = —(CH2)NMe2; n = 1, R = —(CH2)OEt; n = 4, R = —(CH2)COOEt; n = 3, R = —(CH2)Me, have been prepared and characterized. Functional group loadings of ∼4 mol % (x = 1, y = 25), ∼11 mol % (x = 3, y = 23), and ∼30 mol % (x = 8, y = 18) were obtained by reacting commercially available copolymers Me3SiO(MeSi{H} O)x(Me2SiO)ySiMe3 with the appropriate ratios ofx:y, with the required quantities of HO(CH2)nR, using dichloro(1,5‐cyclooctadiene)platinum(II) as catalyst. Amine, ether, ester, and alkyl functionalized siloxanes were obtained in good yields after purification, and each fluid polymer has been characterized by 1H and 13C‐nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectral measurements, elemental analysis, viscosity, surface tension, and density measurements. The functionalized polymers exhibit Newtonian behavior over the range of shear rates 0.4–79.4 s−1, and significant viscosity enhancements were observed for all functionalized polymers compared with poly(dimethylsiloxane) fluids of similar chain lengths. The functionalized siloxanes exhibited in almost all cases an increase in both viscosity and density as the functional group loading increased. The surface tensions of the polymers have also been determined and lie within the range 18.8–22.3 mN m−1. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 808–817, 2001
Synthesis and the magnetic properties of novel metal(II) complexes of polyamides
Authors: Liu Jiageng , Sun Weilin , Lu Fengcai
Published: October 2004

Novel polyamides DTPA and DTPyA are prepared from 2,2′‐diamino‐4,4′‐bisthiazole and aromatic polycarbonyl chloride. The complexes of Fe(II) and Cu(II) metal of the polyamides are also prepared. The complexes as well as the polyamides are characterized through IR and EPR, and the magnetic property of each complex are measured through MPMS. It is found the Fe(II) complexes of both DTPA and DTPyA reveal magnetization ability, especially the Fe(II) DTPA complex. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 818–822, 2001
The production of a high‐functionality RBD palm kernel‐based polyester polyol
Authors: Badri K. H. , Ahmad S. H. , Zakaria S.
Published: October 2004

In the previous article, a diol‐based RBD palm kernel polyol was prepared. It has been found that the polyurethane foam produced is only giving a good compressive strength property at 45 kg/m3 molded density. The combination of sorbitol into the polyol system resulted in a better dimensional stability and improved thermal conductivity as well as enhanced the compressive strength. These were obtained by increasing the functionality of the polyol (functionality of 4.5) through introduction of high molecular weight and branching polyhidric compound. Direct polycondensation and transesterification methods were used for the syntheses. The hydroxyl value, TLC, and the FTIR were determined to study the completion of the reaction. A comparative study of the mechanical properties and morphological behavior was carried out with the diol‐based polyol. From the water‐blown molded foam (zero ozone depletion potential ODP) with density of about 44.2 kg/m3 and closed‐cell content of 93%, it resulted in a compressive strength of 222 kPa, dimensional stability of 0.09, 0.10, and 0.12% at the length, width, and thickness of the foam, respectively, conditioning at −15°C for 24 h. The thermal conductivity improved to an initial value of 0.00198 W/mK, tested at 10°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 827–832, 2001
Influence of the molecular structure on slow crack growth resistance and impact fracture toughness in Cr‐catalyzed ethylene‐hexene copolymers for pipe applications
Authors: Stephenne V. , Daoust D. , Debras G. , Dupire M. , Legras R. , Michel J.
Published: October 2004

In this study we correlate parameters describing molecular structure (molar mass distribution, short chain branching content, intermolecular heterogeneity) of different ethylene‐hexene Cr‐catalyzed copolymers, with slow crack growth and rapid crack propagation resistances, respectively measured with Bent Strip and Charpy tests. The PTREF technique, coupled with classical techniques, was used. Two new indices were proposed to correlate mechanical properties and molecular structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 916–928, 2001
Vulcanization characteristics of asphalt/SBS blends in the presence of sulfur
Authors: Wen Guian , Zhang Yong , Zhang Yinxi , Sun Kang , Chen Zhiyong
Published: October 2004

The vulcanization of asphalt/styrene–butadiene–styrene (SBS) triblock copolymer blends in the presence of elemental sulfur was followed with a strain‐controlled rheometer. The vulcanization of the blends took place at temperatures greater than 140°C. From 150 to 180°C, the curing rate of the blends increased significantly with increasing temperature, and the apparent activation energy of vulcanization was 45.2 kJ mol−1. A suitable processing temperature for good mechanical and thermally stable properties was between 170 and 180°C. Both the structure of SBS and the sulfur level had important effects on the vulcanization of the blends. A plot of the electric current versus time showed the process of the dynamic vulcanization of the blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 989–996, 2001
Synthesis and thermal behavior of thermotropic terpolymers based on 8‐(3‐hydroxyphenyl)octanoic acid, 2,6‐naphthalenedicarboxylic acid, and substituted hydroquinones
Authors: Vijayanathan Veena , Prasad V. S. , Pillai C. K. S.
Published: October 2004

Aromatic–aliphatic thermotropic liquid crystalline terpolyesters derived from 2,6‐naphthalenedicarboxylic acid, hydroquinones, and 8‐(3‐hydroxyphenyl)octanoic acid (HPOA), a monomer with built‐in kink and flexible moieties, were prepared by a melt polycondensation reaction. These polymers were characterized for their thermotropic liquid crystalline properties. The effect of variation in the composition of the polyester on the liquid crystalline behavior and thermal properties was also studied. Increasing the content of kinked units increased the amount of structural irregularity and decreased the isotropization temperature. The Tm and thermal stability of the polyesters were found to decrease with increase in the HPOA content. The formation of the liquid crystalline phase was not prevented by the introduction of up to 40 mol % of HPOA in the copolyester. The effect of substituents on the thermal properties of the terpolyesters was also studied. Introduction of a phenyl substituent on the hydroquinone ring was found to lower the transition temperature compared to substituents such as methyl or methoxy. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1021–1029;2001
Particle nucleation mechanism for the emulsion polymerization of styrene with a novel polyester emulsifier
Authors: Chang Yih‐Her , Lee Yu‐Der , Karlsson Ola J. , Sundberg Donald C.
Published: October 2004

The particle nucleation mechanism in emulsion polymerization of styrene with a novel polyester emulsifier, 5‐sulfoisophthalic acid dimethyl ester sodium salt‐modified tetracarboxylic acid‐terminated polyester (SMTAPE), was investigated. The consumption of SMTAPE micelles was monitored by the measurement of surface tension during the emulsion polymerization. Kinetic studies and emulsifier consumption clearly showed that a continuous nucleation mechanism without Smith–Ewart interval II was characteristic of this system. It was attributed to the high concentration of SMTAPE emulsifier in the polymerization, which led to a large surface area and a vast number of micelles around 10 nm in size that served as the major locus of particle nucleation. A broad particle size distribution was observed throughout the reaction, and the nucleation period lasted well into the reaction until the disappearance of the micelles or the disappearance of monomer droplets. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1061–1070, 2001
Characterization of cellulose aldehyde using Fourier transform infrared spectroscopy
Authors: Fan Q. G. , Lewis D. M. , Tapley K. N.
Published: October 2004

Fourier transform infrared spectroscopy has been used to study cellulose aldehyde groups in bleached cotton, unbleached cotton, and in periodate oxidized cotton. Second derivative spectroscopy could reproducibly identify aldehyde bonds in oxidized cotton only if the samples were predried at 110°C for 24 h; the aldehyde band appeared at 1732–1734 cm−1. Diffuse reflectance spectroscopy in the Environmental Chamber readily detected the above aldehyde absorbances at temperatures above 100°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1195–1202, 2001
Synthesis and adsorption properties of magnetic resin microbeads with amine and mercaptan as chelating groups
Authors: Zhang Chaocan , Li Xi , Pang Jinxing
Published: October 2004

Three magnetic chelating resins containing amino and mercapto groups were prepared by the suspended condensation polymerization of 2‐chloroethoxymethyl thiirane with diamines. The magnetic resins were microbeads whose diameter was in the range of 10 to 45 μm. The structure of the resins was characterized by XPS, IR, and elemental analysis. Their adsorption properties for Hg(II), Au(III), Pd(II), Pt(IV), Ag(I), Cu(II), Zn(II), and Pb(II) were investigated. The experimental results show the magnetic resins have high affinity for Hg(II) and noble metal ions. In the competitive adsorption, the resins predominantly adsorbed Hg(II) or Pd(II) in the coexistence of Cu(II), Zn(II), and Mg(II). Desorption of Pd(II) loaded on the resins was studied by using 2M hydrochloric acid solution containing 1% thiourea as desorbent. A high desorption ratio (up to 96.5%) was observed, and repeated adsorption/desorption operations showed the probability of repeated use of the magnetic resins. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1587–1592, 2001
Study of adsorption of nonionic surfactants at the liquid–solid interface by FTIR/CIR
Authors: Mansur Claudia R. E. , Benzi Márcia R. , Lucas Elizabete F.
Published: October 2004

Fourier transform infrared spectroscopy (FTIR), using the attenuated total reflectance (ATR) method, can be used to characterize the interface of a system. We investigated the adsorption at the liquid–solid interface of nonionic surfactant aqueous solutions with or without a hydrotropic agent. We studied monofunctional diblock copolymers of poly(ethylene oxide‐propylene oxide) (PEO–PPO) as nonionic surfactants and sodium p‐toluenesulfonate (NaPTS) as hydrotropic agent. The samples were analyzed by FTIR technique using the circular internal reflectance (CIR) accessory, which confirmed that the hydrotrope shifts the surfactant from the liquid–solid interface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1668–1676, 2001
Applications of epoxidized and hydroxy‐fluoroester pendent secondary high‐molecular‐weight guayule rubber in coatings
Authors: Gupta Sandhya , Mendon Sharathkumar K. , Thames Shelby F.
Published: October 2004

The epoxidation of secondary high‐molecular‐weight guayule rubber to yield epoxidized guayule rubber (EGR) and the subsequent opening of the oxirane rings by fluoroacids to yield fluorinated guayule rubber (FGR) were reported in an earlier article.1 The oxirane and hydroxyl groups that occur in EGR and FGR, respectively, enable these derivatives to be integrated into the binder system of coatings. The coating industry has long been interested in nontoxic multifunctional crosslinking agents that do not emit volatile organic compounds (VOCs). Ring‐opening reactions of epoxides and reactions between hydroxyl and isocyanate groups are prime examples of crosslinking that do not emit VOCs. This study was conducted to ascertain the viability of guayule rubber derivatives that contain epoxide and hydroxyl groups as crosslinking agents in solvent‐based coatings and powder coatings. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1718–1724, 2001
Block copolymer formation from the melt reaction between polycarbonate and poly(ethylene‐co‐butylene) diol
Authors: Lee Sukmin , Park Jun Sang , Lee Hosull
Published: October 2004

The block copolymer formation from the exchange reaction between polycarbonate (PC) and poly(ethylene‐co‐butylene) diol (POH) occurring during melt mixing was studied. The exchange reaction proceeded by the attack of active chain ends of hydroxyl‐terminated POH on the inner carbonate groups of PC. The reaction was accelerated in basic condition in the presence of a hindered amine. The formation of block copolymer was confirmed by 1H–NMR analysis. The proceeding of the exchange reaction was analyzed with UV spectrometry by measuring the absorbance at 285 nm of the less‐reactive phenolic end group of PC oligomers produced. The reaction was terminated when the hydroxyl end groups of POH were completely consumed. It was found from the analyses by GPC and DSC that the exchange reaction between PC and POH takes place rather uniformly by random scission of the chain. The block copolymer obtained here will be employed as a compatibilizer of PC/polyolefin blends in a future study. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1725–1732, 2001
Characterization of grafting in the emulsion polymerization of vinyl acetate using poly(vinyl alcohol) as stabilizer
Authors: Egret Hélène , Dimonie Victoria L. , Sudol E. David , Klein Andrew , El‐Aasser Mohamed S.
Published: October 2004

Emulsion polymerizations of vinyl acetate (VAc) with polyvinyl alcohol (PVA) as emulsifier were carried out by both batch and semicontinuous processes. The extent of grafting of vinyl acetate onto the PVA chains was investigated by a new method for separating the various polymer fractions in high solids content latexes. The quantification was carried out by a three‐step separation and selective solubilization of the PVAc latexes. After the separation, the water‐soluble PVA and the solvent‐soluble PVAc components were characterized by gel permeation chromatography and 13C–NMR, from which the accuracy of this method was verified. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1739–1747, 2001
Achieving compatibility in blends of low‐density polyethylene/polyamide‐6 with addition of ethylene vinyl acetate
Authors: Taşdemi̇r Münir , Yildirim Hüseyin
Published: October 2004

Polymer alloys and blends, whose major advantage is the potential of achieving a range of physical and mechanical properties, have continued to be a subject of interest over recent years. Addition of a block or graft copolymer, with chemically similar segments to those involved in the polymer blend considered, led to a variety of desirable properties. The copolymer added to the blend functioned to promote a homogeneous dispersion of the constituent phases and to enhance their mutual adhesion. Such agents that enable better dispersion in polymer blends are known as compatibilizers. In this study an attempt has been made to improve the compatibility in a polymer blend composed of two normally incompatible constituents, LDPE and PA6, by addition of a compatibilizer. The compatibilizer agent, ethylene vinyl acetate (EVA), was added to the polymer blend in ratios of 1, 5, and 10% by using a twin‐screw extruder. The effect of EVA on the crystallization of the polymer constituents was observed through DSC examinations. Furthermore, the control sample and all three blends of LDPE/PA6/EVA were subjected to examinations to obtain their yield and tensile strengths, elasticity modulus, percentage elongation, izod impact strength, hardness, and melt flow index. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1748–1754, 2001
Elastic polyaniline with EPDM and dodecylbenzenesulfonic acid as plasticizers
Authors: Faez Roselena , De Paoli Marco‐A
Published: October 2004

Elastomeric polyaniline was prepared by being mixed with ethylene–propylene–diene (EPDM) rubber in low concentrations (10, 20, or 30 wt %). The mixture was made in an internal mixer coupled to a torque rheometer. The polyaniline was doped with dodecylbenzenesulfonic acid (DBSA) via reactive processing during the mixing. When the EPDM rubber was added to the polyaniline and DBSA, the doping reaction was not interrupted, as demonstrated by an increase in the torque values. We chose the relative DBSA and EPDM concentrations to obtain the highest conductivities (10−1 to 10−3 S cm−1) and the best mechanical properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1768–1775, 2001
Dynamic properties of an organic hybrid of chlorinated polyethylene and hindered phenol compound
Authors: Wu Chifei , Otani Yoshio , Namiki Norikazu , Emi Hitoshi , Nitta Koh‐Hei , Kubota Saburo
Published: October 2004

The dynamic mechanical properties of hybrids of chlorinated polyethylene (CPE) and 3,9‐bis[1,1‐dimethyl‐2{β‐(3‐tert‐butyl‐4‐hydroxy‐5‐methylphenyl)propionyloxy}ethyl]‐2,4,8,10‐tetraoxaspiro[5,5]‐undecane (AO‐80) were investigated. The CPE/AO‐80 hybrids showed a novel relaxation in addition to the glass transition of CPE. The novel relaxation is attributed to the dissociation of intermolecular hydrogen bonds within the AO‐80–rich domain. The Payne effect, that is, the decrease of the storage modulus E′ with increasing strain amplitude and the appearance of a loss modulus E″ maximum at a strain of 0.6%, was observed for the CPE/AO‐80 hybrids. This result demonstrates that the AO‐80–rich domains within matrix polymer CPE form a network. The Payne effect is considered to be attributed to the mechanical disruption of segment–segment contacts at a sufficiently great strain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1788–1793, 2001
Toughening of epoxy resin by functional‐terminated polyurethanes and/or semicrystalline polymer powders
Authors: Wang Huei‐Hsiung , Chen Jung‐Chieh
Published: October 2004

Hydroxyl‐, amine‐, and anhydride‐terminated polyurethane (PU) prepolymers, which were synthesized from polyether [poly(tetramethylene glycol)] diol, 4,4′‐diphenylmethane diisocyanate, and a coupling agent, bisphenol‐A (Bis‐A), 4,4′‐diaminodiphenyl sulphone (DDS), or benzophenonetetracarboxylic dianhydride, were used to modify the toughness of Bis‐A diglycidyl ether epoxy resin cured with DDS. Besides the crystalline polymers, poly(butylene terephthalate) (PBT) and poly(hexamethylene adipamide) (nylon 6,6), with particle sizes under 40 μm were employed to further enhance the toughness of PU‐modified epoxy at a low particle content. As shown by the experimental results, the modified resin displayed a significant improvement in fracture energy and also its interfacial shear strength with polyaramid fiber. The hydroxyl‐terminated PU was the most effective among the three prepolymers. The toughening mechanism is discussed based on the morphological and the dynamic mechanical behavior of the modified epoxy resin. Fractography of the specimen observed by the scanning electron microscopy revealed that the modified resin had a two‐phase structure. The fracture properties of PBT‐particle‐filled epoxy were better than those of nylon 6,6‐particle‐filled epoxy. Nevertheless, the toughening effect of these crystalline polymer particles was much less efficient than that of PU modification. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2903–2912, 2001