bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of grafting with acrylic monomers on the viscosity, gelatinization temperature, and granule swelling characteristics of starch
Authors: Aravindakshan P. , Kumar V. G. 
Published: October 2004

AbstractAmylography and scanning electron microscopy (SEM) studies on grafted copolymers of starch with methacrylic acid and methyl methacrylate demonstrated significant changes in the viscosity and granule disintegration characteristics, depending on the extent of grafting and the nature of the monomer. Marked viscosity changes were observed when the carboxyl groups of the starch‐graft‐poly(methacrylic acid) (SPMAA) were neutralized with sodium hydroxide. The viscosity modification was found to be dependent on the extent of neutralization, and a maximum was observed at 10–25% neutralization. With an increase in extent of neutralization, there was a decrease in gelatinization temperature. For a sample of SPMAA with a percentage grafting of 14.1, the gelatinization temperature decreased from 64°C for the acid form to 42°C for the fully neutralized form. The gelatinization temperature of the fully neutralized samples of SPMAA showed a linear relationship with the percentage grafting. SEM was used to elucidate the effect of grafting on the granule swelling characteristics of starch at various temperatures. In the case of starch‐graft‐polymethyl methacrylate (SPMMA), granule disruption on heating with water was observed. However, this did not lead to the build‐up of viscosity on gelatinization. This was explained to be caused by the hydrophobic nature of SPMMA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 528–534, 2002; DOI 10.1002/app.10266
Semicrystalline polyimide matrices for composites: Crystallization and properties
Authors: Yudin V. E. , Svetlichnyi V. M. , Gubanova G. N. , Didenko A L. , Sukhanova T. E. , Kudryavtsev V. V. , Ratner S. , Marom G. 
Published: October 2004

AbstractNew semicrystalline polyimide/oligoimide blends, designated for matrices in carbon fiber‐reinforced composites, were developed. A specific advantage of the proposed polyimides is their ability to crystallize from the melt, therein retaining their crystallinity throughout the manufacturing process. The generation of crystallinity after melting, referred to as recrystallization, was investigated here as affected by blending the polyimides with oligoimides of a similar chemical structure. Based on thermal analysis and enthalpy measurements, comparative X‐ray diffraction analyses, and polarized light microscopy of hot‐stage‐controlled crystallization, the recrystallization ability was determined for five different oligoimides. In some cases, the addition of oligoimides, both amorphous and crystalline, resulted in complete recrystallization. The main contribution of the oligoimides is suggested to be through plasticization, allowing segmental chain mobility during crystallization, and not via nucleation. A similar effect was obtained by lowering the molecular weight of the polyimide; this, however, generates mechanical property reduction, rendering the polyimide irrelevant to composite materials. Finally, it was shown that crystallization was also enhanced by carbon fibers, serving as a nucleating agent and generating transcrystallization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2873–2882, 2002; DOI 10.1002/app.10277
Modification of polyolefins with silicone copolymers. II. Thermal, mechanical, and tribological behavior of PP and HDPE blended with silicone copolymers
Authors: Yilgor Emel , Sinmazcelik Tamer , Yilgor Iskender 
Published: October 2004

AbstractThermoplastic polyolefin (TPO) films with permanent, silicone‐rich, low‐friction, low‐abrasion surfaces were obtained by melt blending of high‐density polyethylene (HDPE) and polypropylene (PP) with polydimethylsiloxane (PDMS)‐containing block copolymers. Two different block copolymers, a siloxane–urea segmented copolymer and a polycaprolactone‐b‐PDMS triblock copolymer were used as modifiers at levels between 0.1 and 5.0% by weight. Blends were prepared in a twin‐screw extruder. Modified films displayed surfaces with very low friction coefficients and high abrasion resistance, which depended on the type and the level of additive incorporated into the system. Bulk properties of these modified systems, such as crystallization and melting behavior or tensile properties, were not affected. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 535–540, 2002; DOI 10.1002/app.10279
Surface morphology evaluation of polymer beads based on divinylbenzene by atomic force microscopy
Authors: Neves Márcia A. F. S. , Coutinho Fernanda M. B. , Dias Marcos L. , Simão Renata A. , Achete Carlos A. 
Published: October 2004

AbstractMacroporous poly(styrene‐co‐divinylbenzene) and poly(divinylbenzene) beads were synthesized by modified suspension polymerization in the presence of different mixtures of toluene and heptane as porogen agent. Through atomic force microscopy, it was possible to identify the microspheres and the channels between them that constitute the bead pores. It was also possible to make a comparison with the results obtained by nitrogen desorption, a traditional technique used to determine the porosity of macroporous copolymers in the dry state. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 541–551, 2002; DOI 10.1002/app.10290
Syntheses of bismaleimides with ester units and their polymerization with diamines
Authors: Sava M. 
Published: October 2004

AbstractFive structurally different bismaleimides were synthesized by reaction between 3(4)‐maleimidobenzylchloride with various diphenols. They were characterized by infrared (IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy. Thermal characterization of monomers and their polymers was accomplished by differential scanning calorimetry (DSC) and dynamic thermogravimetric analysis (TGA). Polyaminobismaleimides having inherent viscosities of 0.1–0.4 dL/g were prepared by Michael addition of diamines to bismaleimides. The polymers are soluble in solvents as DMF, NMP, and DMSO, and afforded film from their solutions. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 750–757, 2002; DOI 10.1002/app.10294
Liquid crystalline copolyester/polyethylene in situ composite film: Rheology, morphology, molecular orientation, and tensile properties
Authors: Nakinpong Teeranant , Bualek‐Limcharoen Sauvarop , Bhutton Angkana , Aungsupravate Ornsiri , Amornsakchai Taweechai 
Published: October 2004

AbstractA thermotropic liquid crystalline copolyester (TLCP) was blended with low density polyethylene using a corotating twin screw extruder and then fabricated by extrusion through a miniextruder as cast film. Rheological behavior, morphology, and tensile properties of the blends were investigated. Melt viscosities of neat components and blends measured by using plate‐and‐plate and capillary rheometers at 240°C, in the shear rate range 1–104 s−1, showed similar shear thinning effect. The viscosity values measured by the two techniques in the overlapping range of shear rate are found to be identical, which is in accord with the Cox–Merz rule. Addition of TLCP slightly reduces the matrix melt viscosity. TLCP dispersed phase in the extruded strand appeared in the form of spherical droplets. These droplets were elongated into fibrils with high aspect ratio (length to width) at the film extrusion step. As a result, the Young's modulus in machine direction (MD) of the composite film was greatly enhanced. At 20 wt % of TLCP, the MD Young's modulus was found to be about 16‐fold increase compared to that of the neat polyethylene film. However, the elongation at break sharply dropped with the increase of TLCP content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 561–567, 2002; DOI 10.1002/app.10307
Effect of compatibilization in injection‐molded polycarbonate and liquid crystalline polymer blend
Authors: Tan L. P. , Yue C. Y. , Tam K. C. , Lam Y. C. , Hu X. 
Published: October 2004

AbstractThe effect of compatibilizing polycarbonate (PC) and LC5000, a thermotropic liquid crystalline polymer consisting of 80/20% of hydroxybenzoic acid and poly(terephthalate) with a laboratory synthesized compatibilizer was studied. The compatibilizer was synthesized by transesterification of PC and LC5000 with the aid of a catalyst. The effect of compatibilization was investigated by studying the mechanical and morphological properties of injection‐molded plaques with different thicknesses. Substantial improvement was observed in the mechanical properties after compatibilization. Significant enhancement in the fibrillation was also observed in the samples after addition of compatibilizer. The surface finish of the compatibilized samples was smooth and homogenous as compared to the uncompatibilized samples. The skin‐core phenomenon in the tensile fractured surfaces was less obvious in the former samples, indicating better adhesion and homogeneity. These morphological studies showed that the mechanical properties enhancement lay in improved fibrillation and interfacial adhesion between the dispersed and major phases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 568–575, 2002; DOI 10.1002/app.10308
Novel high‐solids pigmented coatings prepared from a new‐synthesized isophthalate‐based oligoester, a melamine resin, and various fillers
Authors: Diakoumakos Constantinos D. , Jones Frank N. 
Published: October 2004

AbstractA new‐synthesized hydroxyl‐terminated isophthalate‐based liquid oligoester (L‐311), an hexakis(methoxymethylol)melamine resin, and various inert pigments (fillers) such as either kaolins (Al2O3 · 2SiO2 · 2H2O) of different particle sizes (1.50 and 4.80 μm) or calcium metalsilicate (CaSiO3) were used to prepare high‐solids pigmented coatings (PA and PW series, respectively). The physical, chemical, and mechanical properties (pencil hardness, Knoop hardness, flexibility, impact resistance, adhesion, gloss, solvent, and mar resistance) of the new‐formulated pigmented coatings were correlated to the chemical species of the filler, the filler's load and particle size, the quantity of the crosslinker, and the introduction of large particle size colloidal silica into the coating. For measuring the mar resistance of the pigmented coatings, the Taber abrasion method was applied and the inverse wear index, F [=I−1, cycles/cg (wear index l, weight loss (cg) per number of cycles)], was directly related to the mar resistance. Either when kaolins or calcium metalsilicates were used as fillers, the Knoop hardness, the impact, and mar resistance of the films were affected from the filler's load, whereas the quantity of melamine resin (crosslinker) affected the knoop hardness, the gloss, and the mar resistance. The fillers' particle size and the introduction of large particle colloidal silica affected mainly the mar resistance and the gloss, respectively. The pencil hardness of the PW‐pigmented coatings series (F‐2H) was higher than that of the PA‐series (B‐HB). The chemical composition of the inert pigment proved to be a very important parameter in the preparation of pigmented coatings with specific properties that aim to meet modern and particular demands for various end‐up uses. All the new‐formulated high‐solids (nonvolatiles by weight ∼ 70%) pigmented coatings (PA and PW series) presented excellent adhesion (5B), flexibility (> 32%), methyl ethyl ketone (MEK) resistance (>200 rubs), high pencil hardness, good knoop hardness, and very good impact resistance (from 100 up to 160 in.‐lb), independently of the species of the filler (kaolins or calcium metalsilicate). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 576–590, 2002; DOI 10.1002/app.10309
Rigid polyurethane foam prepared from a rape seed oil based polyol
Authors: Hu Yan Hong , Gao Yun , Wang De Ning , Hu Chun Pu , Zu Stella , Vanoverloop Lieve , Randall David 
Published: October 2004

AbstractA new kind of polyol based on rape seed oil for use in rigid polyurethane foam was synthesized and characterized. The synthesis of such a polyol was divided into two steps. The first step was the hydroxylation of the double bonds existing in the long chains of the unsaturated aliphatic hydrocarbon of rape seed oil with peroxy acid. The second step was use of the alcoholysis of the hydroxylated rape seed oil with triethanolamine to increase the hydroxyl value of the product. The reaction process was monitored by means of a novel on‐line infrared spectrometer. Rigid polyurethane foam was produced with this rape seed oil based polyol and some physical properties of the foam were examined and compared with a reference foam. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 591–597, 2002; DOI 10.1002/app.10311
Structures and physical properties of rigid polyurethane foam prepared with rosin‐based polyol
Authors: Jin Jian Feng , Chen Yong Ling , Wang De Ning , Hu Chun Pu , Zhu Stella , Vanoverloop Lieve , Randall David 
Published: October 2004

AbstractRosin‐based polyester polyols were synthesized from a rosin–maleic anhydride adduct, diethylene glycol, and ethylene glycol with and without adding adipic acid and phthelic anhydride, in the presence of catalyst. Rigid polyurethane (PU) foams were prepared with these rosin‐based polyols and compared with foam made with an industrial polyester Daltolac™ P744. The experimental results show that the foaming behavior for the foams prepared from such rosin‐based polyols is similar to that of industrial products, but their 10% compression strength, both parallel and vertical to foaming rise direction, is higher and the dimensional stability at 100 and −30°C is similar or somewhat better than that of a comparable system. Furthermore, the rosin‐modified PU foams exhibit even lower thermal conductivity and much higher activation energies during the pyrolysis process. All these unique physical properties of the rosin‐modified rigid PU foams were correlated to the structures of these PU foams. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 598–604, 2002; DOI 10.1002/app.10312
Ionic elastomers based on carboxylated nitrile rubber (XNBR) and zinc peroxide: Influence of carboxylic group content on properties
Authors: Ibarra L. , Alzorriz M. 
Published: October 2004

AbstractThe properties of ionic elastomers formed in the crosslinking with zinc peroxide are studied in compounds with varying proportions of carboxylic groups in the elastomeric matrix. At the temperature used, 150°C, preferentially ionic bonds were formed. The crosslinking densities and, correspondingly, the physical properties, increased with the acid group content and with the reaction time. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 605–615, 2002; DOI 10.1002/app.10313
Humidity‐induced plasticization and antiplasticization of polyamide 6: A positron lifetime study of the local free volume
Authors: Dlubek G. , Redmann F. , Krause‐Rehberg R. 
Published: October 2004

AbstractPolyamide 6 (PA6) was studied using positron annihilation lifetime spectroscopy (PALS). From theortho‐positronium lifetime τ3the size of local free volumes (holes) was estimated. In dry PA6 the mean hole volumevvaried between 70 Å3and 128 Å3when the temperature increased from 25 to 220°C. From the comparison of the coefficient of thermal expansion of macroscopic volume with that of hole volume a number density of holesNhof 0.8 nm−3was estimated. The mean hole volume of PA6 exposed to atmospheres of different relative humidity (RH) was compared with thev(T) behavior of dry PA6. We propose a phenomenological model in whichTgandvg, the glass transition temperature and the mean hole volume atTg, are allowed to vary withRH. AssumingTg(RH) as given in the literature, thevg(RH) were estimated from our experiments. In the range 0 <RH< 90%, thevgof the humid PA6 was always smaller than in the dry polymer, while nearRH= 100% both values became approximately identical. Two ranges of sorption behavior were observed. For small and mediumRH,vgdecreases by up to 19 Å3forRH= 45%, which corresponds to more than half of the volume of a water molecule. This behavior ofvgwas interpreted as antiplasticization (loss of free volume) of the glassy polyamide. For largerRH,vgincreases again toward the value of dry PA6, indicating a plasticization (gain of free volume) behavior that compensates and finally nullifies the former antiplasticization. The behavior of the local free volume in moist PA6 corresponds well to the known variation of the specific volume. Our results deliver experimental evidence for the decrease in the unrelaxed free volume of the (glassy) water–PA6 mixture with respect to that of the dry glassy polymer. The results are also discussed in terms of a simple hole‐filling model and of the hypothesis of firmly and loosely bound water molecules in polyamides. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 244–255, 2002; DOI 10.1002/app.10319
Surface modification of carbon black by vegetable oil—Its effect on the rheometric, hardness, abrasion, rebound resilience, tensile, tear, and adhesion properties
Authors: Kundu P. P. , Kukreja T. R. 
Published: October 2004

AbstractPlasticizer (vegetable or parafinic oil) pretreated carbon black is mixed with rubber for its compounding. It is observed that the extent of cure obtained from rheometric torque decreases linearly with an increase in vegetable oil content. The presence of a coupling action and a monolayer (microplasticization) of vegetable oil at carbon black–rubber interfaces causes a decrease in tan δ (from rheometric studies), elongation at break, and tensile strength, and increase in abrasion loss, hardness, and 300% modulus up to 3 phr, beyond which all the properties show just the opposite trend with an increase in the content of vegetable oil. Both tear strength and rebound resilience increases with increasing doses of vegetable oil; the rate of increase is slow up to 3 phr due to the coupling action and microplasticization, and it is faster beyond 3 phr due to the presence of both coupling and plasticising action. Upon the addition of a plasticizer, adhesive strength increases up to 1 phr in the case of vegetable oil, and remains almost constant in the case of parafinic oil; beyond 1 phr, adhesive strength decreases due to the presence of a multiple layer of plasticizer between rubber–metal interfaces. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 256–260, 2002; DOI 10.1002/app.10320
Plastic films with improved adhesion on integrated circuit packages for laser marking
Authors: Tang Z. G. , Ravi V. , Zhao J. H. 
Published: October 2004

AbstractVarious plastic films of a melting point above 170°C were selected for IC package in laser marking. These films include: (1) polyacetal, (2) polycarbonate, (3) polyester, and (4) nylon. They are in a form of a homogeneous layer, polymer blend, or multilayer structure. The plastic films were plasma treated and laminated onto the molded compound through transfer molding process. No extra process was introduced except for slight modification of the mold for film placement. The film molded IC package was evaluated in terms of adhesion, laser marking, and thermal and humidity resistance. Design of experiment was employed for the adhesion study. The results indicated that the polymeric material and film thickness were the key parameters affecting film adhesion. Careful selection of the plastic film made it possible for self‐triming during product ejection. Two kinds of plastic films, namely, nylon and polyester, were finalized as laser markable and moldable materials. The laser marking effects of the film‐molded packages were comparatively better than those of the nonfilm‐molded packages. These two films were molded into IC packages and tested for thermal and humidity resistance. The results showed that polyester film‐molded packages exhibited superior reliability in thermal shock tests (1000 cycles) and unbias cooker tests (72 h). © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 758–766, 2002; DOI 10.1002/app.10321
Studies on carboxy‐terminated liquid natural rubber in NBR
Authors: Dileep U. , Avirah Shanti A. 
Published: October 2004

AbstractMaleic anhydride was chemically attached to depolymerized natural rubber by a photochemical reaction. The product Carboxy Terminated Liquid Natural Rubber (CTNR) was characterized by 1H‐NMR, IR, GPC, and TGA. The efficiency and permanence of CTNR were compared with conventional plasticizers in NBR vulcanizates. This polymeric plasticizer was found to be less volatile and more resistant to oil extraction. The vulcanizates showed improved aging resistance compared to vulcanizates containing conventional plasticizers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 261–267, 2002; DOI 10.1002/app.10322
Radiation polymerization of acrylonitrile in a viscous system with styrene
Authors: Badawy Sayed M. , Dessouki Ahmed M. 
Published: October 2004

AbstractRadiation polymerization of acrylonitrile in a viscous system with styrene was performed at ambient temperature by using γ‐rays. It is found that the overall rate of polymerization was accelerated after critical conversion due to the gel effect. As the molar fraction of styrene in monomer feed (fSt) is increased, both the total polymer conversion and molar fraction of acrylonitrile in the copolymer feed (FAN) were decreased. The monomer reactivity ratios for acrylonitrile and styerne were determined to be r1 (AN) = 0.25 and r2 (St) = 2.0, respectively. The copolymers obtained were characterized by Fourier transformed infrared spectra (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), 1H‐NMR, and pyrolysis mass spectrometry (PMS). It was found that the slight addition of styrene to acrylonitrile strongly changes crystallinity, morphology, and thermal decomposition of the resulting polymer. 1H‐NMR measurment of AN/St copolymer showed the appearance of aromatic proton signals and shifted the resonance of the methylene proton to lower chemical shifts. The mass spectra of AN/St copolymers showed fragments of pyrolysates corresponding to oligonitriles with styrene end groups. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 268–275, 2002; DOI 10.1002/app.10324
Lactam–amide graft copolymers as novel support for enzyme immobilization
Authors: De Queiroz Alvaro A. A. , Vargas Reinaldo R. , Higa Olga Z. , Ribeiro Roberto R. , Vítolo Michele 
Published: October 2004

AbstractA graft random copolymer of N‐vinyl‐2‐pyrrolidone and N,N′‐dimethylacrylamide onto polypropylene was synthesized using a simultaneous gamma radiation technique from a 60Co source, so that the hydrogel poly(propylene‐g‐vinylpyrrolidone‐co‐N,N′‐dimethylacrylamide) [PP‐g‐(VP‐co‐DMAM)], thus produced by grafting, could be used as a support for enzyme immobilization. The grafted spheres showed very good swelling behavior in water due to the incorporation of hydrophilicity in the PP spheres. The influence of pH and temperature on as well as the determination of the kinetic parameters, KM and Vmax, for both immobilized and soluble invertase were determined. PP‐g‐(VP‐co‐DMAM) grafting onto the PP spheres caused a significant change in the water content of the support and was more pronounced for the spheres with a high degree of grafting. A porous structure of the polymeric spheres was observed by scanning electron microscopy (SEM). The porous structure contributed to the reaction rate decrease due to diffusional effects, as shown by the larger KM value observed for immobilized invertase relative to the free enzyme. The enzyme affinity for the substrate (KM/Vmax) remains quite good after immobilization. The thermal stability of immobilized invertase was significatively higher than that of the free enzyme and a displacement of 20°C was observed for the immobilized enzyme. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 767–777, 2002; DOI 10.1002/app.10326