bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Rosin‐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

The 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

Polyamide 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

Plasticizer (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

Various 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

Maleic 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

Radiation 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

A 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
Ammonia adsorption behavior of polypropylene nonwoven fabric grafted with acrylic acid
Authors: Kim Sang Yool , Choi Chang Nam
Published: October 2004

An attempt was made to synthesize an adsorbent by the photoinduced grafting of acrylic acid (AA) onto polypropylene nonwoven fabrics using benzophenone (BP) as a photosensitizer in a CH3OH/H2O medium. As the BP concentration was increased, the graft yield was increased up to a specific value and then decreased, and the effect of AA concentration showed the same tendency. It was also found that the graft yield increased with the reaction time and temperature. The amounts of ammonia adsorbed onto polypropylene nonwoven fabrics grafted with AA (PP‐g‐AA) were dependent on the graft yield, adsorption time, and ammonia gas pressure. The adsorption capacity of PP‐g‐AA was 5.86 mmol/g at the graft yield of 116.6%, which was much higher than that of active carbon or silica gel. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 295–301, 2002; DOI 10.1002/app.10328
Organophosphorous additive for fortification, processibility, and flame retardance of epoxy resins
Authors: Zerda Adam S. , Lesser Alan J.
Published: October 2004

Amine‐cured epoxy resins are prepared containing an aliphatic phosphonate additive which aids in the processing of the epoxy by reducing the viscosity of the resin mixture. The additive also acts as an antiplasticizer in the cured epoxy by increasing the modulus and yield strength under uniaxial tension and compression. Additionally, phosphonates are known to behave as flame retardants and dimethyl methyl phosphonate (DMMP) demonstrates a reduction in the rate of thermal degradation and the heat‐release rate upon pyrolysis. Addition of the antiplasticizer reduces the Tg and suppressed β‐relaxations, while effectively increasing the density of the material. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 302–309, 2002; DOI 10.1002/app.10329
Syntheses and properties of carboxymethyl chitosan/urea–formaldehyde snake‐cage resins
Authors: Qu Rongjun , Sun Yanzhi , Wang Chunhua , Lu Shulai , Yu Huimei , Cheng Guoxiang
Published: October 2004

A series of novel snake‐cage resins were synthesized using carboxymethyl chitosan (CM‐CTS) as the snake resin and urea–formaldehyde resin (UF) as the cage resin. Such factors as the optimal synthesis conditions, content of the crosslinking agent, and sorption capacities for metal ions of the above‐mentioned resins were investigated. The experimental results show that these resins have appropriate swelling properties and good mechanical stability. They do not run off in water, HCl, and NaOH aqueous solutions. To form a stable network system, NH4Cl was used as a crosslinking agent to crosslink urea and formaldehyde in synthesis. The sorption experiment showed that the sorption properties of the resins in the presence of the crosslinking agent NH4Cl are better than those without a crosslinking agent. The investigation of the FTIR spectra indicated that the chelate groups, such as —OH, —CO and NHCH2CO, in snake‐resin molecules participated in the coordination with the metal ions, but the —CO bonds in the cage resin UF did not. The snake resin CM‐CTS in the snake‐cage resins was the major contributor of sorption. The sorption dynamics showed that the sorption was controlled by liquid film diffusion. The isotherms can be described by Freundlich and Langmuir equations. The saturated sorption capacities of the resins for Cu2+, Ni2+, Zn2+, and Pb2+ were 1.48, 0.78, 0.13, and 0.02 mmol g−1, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 310–317, 2002; DOI 10.1002/app.10331
Influence of HZSM‐5 catalyst on the thermal degradation of poly(vinyl chloride) in solution
Authors: Chattopadhyay Sujay , Madras Giridhar
Published: October 2004

The kinetics of thermal degradation of poly(vinyl chloride) (PVC) in solution was investigated at various temperatures (210–250°C). The degradation rate coefficients were determined from the time evolution of the molecular weight distribution (MWD). The energy of activation, determined from the temperature dependence of the rate coefficient, was 26.6 kcal/mol. The degradation of PVC was also studied in the presence of a catalyst (HZSM‐5 zeolite). The results indicated that increase of the degradation rate of PVC is first order with the HZSM‐5 concentration up to 50 g/L and zero order at higher concentrations. The thermal degradation kinetics of PVC in the presence of 50 g/L of the catalyst was studied at various temperatures. The temperature dependency of the rate coefficient was used to calculate the activation energy (21.5 kcal/mol). This is consistent with the observation that the presence of a catalyst generally decreases the activation energy and promotes degradation. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 791–796, 2002; DOI 10.1002/app.10332
Synthesis of anionic water‐borne polyurethane with the covalent bond of a reactive dye
Authors: Wang Huei‐Hsiung , Gen Chi‐Tzon
Published: October 2004

We successfully synthesized an anionic water‐borne polyurethane (PU) capable of reacting with a reactive dye to form a covalent bond with the dye molecule. The anionic water‐borne PU was synthesized and grafted with the reactive dye to form a dyed PU. First, the PU prepolymer was synthesized from 4,4′‐methylene bis(isocyanatocyclohexane), poly(tetramethylene glycol), 2,2′‐bis(hydroxymethyl) propionic acid (as an anionic center), and triethyleneamide (as a neutralizer). Then, pure water was added to emulsify and disperse the prepolymer to form an anionic water‐borne PU prepolymer. Finally, the extender N‐(2‐hydroxyethyl) ethylene diamine was used to extend the anionic water‐borne prepolymer to form a PU polymer with hydroxyl groups that could further react with the reactive dye molecule. With respect to the heating properties, the dyed PU polymers exhibited higher glass‐transition temperatures of the hard segment than those without dye molecules. However, neither the glass‐transition temperature of the soft segment nor the melting temperature of the soft segment varied in the presence of dye molecules, but they were changed with various chain lengths of the soft segment. As for the mechanical properties, the modulus and strength of the dyed PU polymers decreased because of the bulkiness of their dye molecules, but the breaking elongation increased. Moreover, the inherent viscosity decreased in the presence of the dye molecules. As for the dyeing properties, the percentage of dye grafting was greater than 90%. The dye‐grafted PU exhibited a lower percentage of migration than PU extended with ethylene diamine (without hydroxy groups) and also showed a higher grade of colorfastness to light. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 797–805, 2002; DOI 10.1002/app.10336
Synthesis and flocculation properties of poly(diallyldimethyl ammonium chloride–vinyl trimethoxysilane) and poly(diallyldimethyl ammonium chloride–acrylamide–vinyl trimethoxysilane)
Authors: Zhao Hua‐Zhang , Luan Zhao‐Kun , Gao Bao‐Yu , Yue Qin‐Yan
Published: October 2004

Poly(diallyldimethyl ammonium chloride–vinyl trimethoxysilane) [P(DADMAC–VTMS)] and poly(diallyldimethyl ammonium chloride–acrylamide–vinyl trimethoxysilane) [P(DADMAC–AM–VTMS)], the latter a new cationically charged and hydrophobically modified flocculant, were obtained by radical polymerization initiated by potassium persulfate. The effects of the vinyl trimethoxysilane (VTMS) feed ratio on the intrinsic viscosity and solubility of the polymers were examined. The effects of the flocculants on turbidity removal, decolorization, and oil removal in water treatment were also studied. The introduction of VTMS increased the intrinsic viscosities of P(DADMAC–VTMS) and P(DADMAC–AM–VTMS) in comparison with the viscosities of poly(diallyldimethyl ammonium chloride) and poly(diallyldimethyl ammonium chloride–acrylamide), respectively, but reduced their solubilities. The introduction of VTMS also enhanced the flocculation properties of P(DADMAC–VTMS) and P(DADMAC–AM–VTMS), including turbidity removal, decolorization, and oil removal. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 335–342, 2002; DOI 10.1002/app.10339
A study on the synthesis and application of an inverse emulsion of amphoteric polyacrylamide as a retention aid in papermaking
Authors: Lu Shaojie , Liu Ruixian , Sun Ximing
Published: October 2004

A series of amphoteric polyacrylamides with different molecular weights and charges were prepared by the copolymerization of acrylamide with sodium acrylate and a subsequent Mannich reaction. The copolymerization was carried out with a redox initiation system via inverse emulsion polymerization. Reaction conditions, factors affecting emulsion stability, and applications as retention aids in papermaking were studied. Experiments showed that an ideal retention aid and a stable latex with wheat‐straw pulp of a shorter fiber length could be obtained under the following conditions: the acrylamide/formaldehyde/dimethylamine ratio was 1/1/1.2, a medium of aldehyde and amine was prepared first and then was dropped into an inverse emulsion of anionic polyacrylamide, the reaction temperature was 45°C, the reaction time was 4 h, and the pH was 5.0. When the anionic degree was 5%, the cationic degree was greater than 20%, the molecular weight was between 2 and 3 million, and the filler retention was higher. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 343–350, 2002; DOI 10.1002/app.10340
Kinetics of the solid‐state polymerization of nylon‐6
Authors: Xie Jian‐Jun
Published: October 2004

The kinetics of the thermally induced solid‐state polymerization (SSP) of nylon‐6 were examined in both a fixed‐bed reactor and a rotary reactor. Factors such as the regulator content, the reaction temperature and time, the particle size, the type and geometry of the nylon‐6 prepolymer, the nitrogen gas flow rate, the water content of the nitrogen gas flow, and the polymerization process were studied. The results showed that the regulator content, the reaction temperature and time, and the particle size were the primary factors, and that the others were negligible. Moreover, the SSP rate and number‐average molecular weight (Mn) increased with increasing reaction temperature and time and decreasing particle size. The SSP rate and Mn had maximum values with increasing regulator content in an experimental range of 0.03–0.07 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 616–621, 2002; DOI 10.1002/app.10341
Effect of interfacial interaction on the mechanical properties of electron beam irradiated HDPE/STC blend
Authors: Xu Wen , Liu Pengbo
Published: October 2004

Some oxygen‐containing groups (mainly CO group) are introduced on the molecular chain of HDPE during electron beam irradiation in air. The affinity between HDPE and sericite–tridymite–cristobabite (STC), the dispersion of STC in HDPE matrix are improved owing to the polar groups introduced. By treating STC with amino‐containing silane coupling agent, the interfacial adhesion between irradiated HDPE (e‐HDPE) and treated STC (t‐STC) is further improved, the mechanical properties of e‐HDPE/t‐STC blend are improved quite a lot. The experimental results show that due to the improvement of interfacial interaction, the interfacial phase can transmit the stress subjected to the HDPE matrix and make the matrix absorb energy by plastic yield or deformation; the impact strength of e‐HDPE/t‐STC blend is thus improved. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 814–820, 2002; DOI 10.1002/app.10345
Chain‐extended polyurethanes—Synthesis and characterization
Authors: Kendagannaswamy B. K. , Siddaramaiah
Published: October 2004

Chain‐extended polyurethanes (PUs) were prepared using castor oil and different diisocyanates such as toluene‐2,4‐diisocyanate and 4,4′‐methylene bis(phenylisocyanate) as a crosslinker and different aromatic diamines like 4,4′‐diaminodiphenyl methane and 4,4′‐diaminodiphenyl sulphone as chain extenders. The effect of aromatic diamines on the swelling and thermal degradation behavior of PU have been discussed. A thermogravimetric analyzer (TGA) curve shows that all the chain‐extended PUs are stable up to 194°C and that maximum weight loss occurs at 490°C. The TGA thermograms show that the thermal degradation of the PUs was found to proceed in two steps. The average molecular weight between crosslinks (M̄c) was determined by swelling studies. The properties imparted by the aromatic chain extenders are explained on the basis of groups present in the diamines. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 359–369, 2002; DOI 10.1002/app.10347
Thermoplastic elastomeric composition based on maleic anhydride–grafted ground rubber tire
Authors: Naskar Amit K. , De S. K. , Bhowmick Anil K.
Published: October 2004

Ground rubber tire (GRT) powder was maleated in an internal mixer using maleic anhydride and dicumyl peroxide at 160°C. Maleated GRT was characterized by using X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, wettability, and differential scanning calorimetry. The physical properties of the dynamically vulcanized 60 : 40, rubber : plastic composition based on acrylated high‐density polyethylene as the plastic phase and ethylene propylene diene rubber containing maleated GRT as the rubber phase were found to be greater than the corresponding composition containing nonmaleated GRT. The blend was found to be reprocessable, like themoplastic elastomers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 370–378, 2002; DOI 10.1002/app.10348
The influence of silane treatment on nylon 6/nano‐SiO2in situpolymerization
Authors: Li Ying , Yu Jian , Guo Zhao‐Xia
Published: October 2004

Silane treatment has been applied to the preparation of nylon 6/nano‐SiO2composites throughin situpolymerization. The influence of such treatment on the reactivity of silica, polymerization of nylon 6, and the mechanical properties of the achieved composites has been studied. Fourier transform infrared (FTIR) spectroscopy and thermal gravimetric analysis (TGA) of silicas isolated from the composites have shown that the conversion of surface silanol groups to amino and epoxy groups did not cause a significant change in the reactivity of silica and that the percentage of silica surface grafting was around 15% for all treated and untreated silicas. End group analysis has shown that the presence of silica (pretreated or not) in the composite system resulted in the decrease of the average molecular weight of the polymer matrix. However, dynamic mechanical analysis and mechanical tests revealed that treating silica with silane improved the strength and toughness of the composite materials, while untreated silica improved their strength at the expense of toughness. This can be attributed to the existence of the flexible interlayer introduced by silane treatment. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 827–834, 2002; DOI 10.1002/app.10349
Effect of components (acrynitril and acrylate acid) on damping properties of poly(styrene‐acrynitril)/poly(ethylacetate‐n‐butylacrylate) latex interpenetrating polymer networks
Authors: Zeng Wei , Li Shucai
Published: October 2004

A series of poly(styrene‐acrynitril)/poly(ethylacetate‐n‐butylacrylate) latex interpenetrating polymer networks (LIPNs) have been synthesized by varying the content of AN and the distribution of acrylate acid. The damping temperature range of the LIPNs was broadened and the damping value increased distinctly when the content of acrynitril was 10%. In low or high temperature range, the damping value of the LIPNs would have a different level of increase with the different distribution of AA in both the networks. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 821–826, 2002; DOI 10.1002/app.10350
Fiber formation from semi‐interpenetrating polymer networks consisting of polycaprolactone and a poly(ethylene glycol) macromer
Authors: Yang K. S. , Park S. H. , Choi Y. O. , Cho C. S.
Published: October 2004

Semi‐interpenetrating polymer networks (SIPNs) consisting of polycaprolactone (PCL) and poly(ethyleneglycol) (PEG) macromer was prepared to improve tensile property in developing biodegradable sutures. When the PEG macromer formed SIPNs with PCL, biodegradability, mechanical strength, and hydrophilicity were improved. The SIPNs fibers formed from the dry spinning process showed an increase of not only tensile strength but also water content with an increase of PEG content. These results represent an increase of the crosslinking density of the PEG network with hydrophobic property. The drawing of SIPNs fibers also further enhanced the tensile strength and the crystallinity of the SIPNs fibers. Unimelting temperature of the SIPNs fiber was observed as an indication of the polymer network without phase separation. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 835–841, 2002; DOI 10.1002/app.10351
Melt‐processable rubber: Chlorinated waste tire rubber‐filled polyvinyl chloride
Authors: Naskar Amit K. , Bhowmick Anil K. , De S. K.
Published: October 2004

Chlorinated ground rubber tire (Cl‐GRT) particles were used as filler in a plasticized polyvinylchloride (PVC) to develop a melt‐processable rubber composition. Physical properties of the Cl‐GRT‐filled PVC compound showed improvement compared to the nonchlorinated counterpart. Interaction between Cl‐GRT and PVC was examined on the basis of results of stress relaxation, dynamic mechanical thermal analysis, and solvent swelling studies. The Cl‐GRT could be loaded upto 40 parts per hundred parts of PVC, and the composition still retains the elastomeric characteristics. The Cl‐GRT‐filled composite was found to be reprocessable like the unfilled PVC compound. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 622–631, 2002; DOI 10.1002/app.10352
Preparation and dynamic mechanical properties of poly(styrene‐b‐butadiene)‐modified clay nanocomposites
Authors: Z. Chen  , Gong K.
Published: October 2004

Polybutyl acrylate (PBA) was intercalated into clay by the method of multistep exchange reactions and diffusion polymerization. The clay interlayer surface is modified, and obtaining the modified clay. The structures of the clay‐PBA, clay‐GA (glutamic acid), and the clay‐DMSO (dimethyl sulfoxide) were characterized using X‐ray diffraction (XRD). The new hybrid nanocomposite thermoplastic elastomers were prepared by the clay‐PBA with poly(styrene‐b‐butadiene) block copolymer (SBS) through direct melt intercalation. The dynamic mechanical analysis (DMA) curves of the SBS/modified clay nanocomposites show that partial polystyrene segments of the SBS have intercalated into the modified clay interlayer and exhibited a new glass transition at about 157°C (Tg3). The glass transition temperature of polybutadiene segments (Tg1) and polystyrene segments out of the modified clay interlayer (Tg2) are about −76 and 94°C, respectively, comparied with about −79 and 100°C of the neat SBS, and they are basically unchanged. The Tg2 intensity of the SBS‐modified clay decreases with increasing the amounts of the modified clay, and the Tg3 intensity of the SBS‐modified clay decreases with increasing the amounts of the modified clay up to about 8.0 wt %. When the contents of the modified clay are less than about 8.0 wt %, the SBS‐modified clay nanocomposites are homogeneous and transparent. The Tgb and Tgs of the SBS‐clay (mass ratio = 98.0/2.0) are −78.39 and 98.29°C, respectively. This result shows that the unmodified clay does not essentially affect the Tgb and Tgs of the SBS, and no interactions occur between the SBS and the unmodified clay. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1499–1503, 2002; DOI 10.1002/app.10353
Intercalation and exfoliation behavior of epoxy resin/curing agent/montmorillonite nanocomposite
Authors: Xu Wei‐Bing , Bao Su‐Ping , He Ping‐Sheng
Published: October 2004

The epoxy resin/curing agent/montmorillonite nanocomposite was prepared by a casting and curing process. The intercalation and exfoliation behaviors of epoxy resin in the presence of organophilic montmorillonite were investigated by X‐ray diffraction (XRD) and dynamic mechanical thermal analysis (DMTA). For the diethylenetriamine curing agent, the intercalated nanocomposite was obtained; and the exfoliated nanocomposite would be formed for tung oil anhydride curing agent. The curing condition does not affect the resulting kind of composite, both intercalation or exfoliation. For intercalated nanocomposite, the glass transition temperature Tg, measured by DMTA and affected by the curing temperature of matrix epoxy resin is corresponded to that of epoxy resin without a gallery. The α′ peak of the loss tangent will disappear if adding montmorillonite into the composite. It was also found that the Tg of the exfoliated nanocomposite decreases with increasing montmorillonite loading. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 842–849, 2002; DOI 10.1002/app.10354
Controlling the morphology of polyurethane/polystyrene interpenetrating polymer networks for enhanced blood compatibility
Authors: Kim J. H. , Kim S. C.
Published: October 2004

Polyurethane (PU)/polystyrene (PS) IPNs were simultaneously synthesized at 80°C, controlling the reaction kinetics to change the morphology. Polymerization kinetics of styrene was controlled by the content of initiator, and that of polyurethane by the catalyst concentration. The effect of the initiator and the catalyst on the polymerization rate was analyzed by NMR spectroscopy and FTIR. Gelation time was also measured by using the advanced rheometric expansion system (ARES). Samples with sea‐and‐island morphology were obtained, when the polymerization rate of PS was relatively slow, and the phase separation time was long. When the polymerization rate of PS was relatively fast, and the phase separation time was short, cocontinuous morphology was obtained. The degree of phase separation and surface roughness decreased, as the rate of PU network formation was increased, and the phase‐continuity was increased. The in vitro blood‐compatibility tests showed that the surface roughness was an important factor on the adsorption of fibrinogens and platelets. A large amount of fibrinogens and platelets were adsorbed on the relatively rough surface of samples showing sea‐island morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 379–387, 2002; DOI 10.1002/app.10358
Conducting systems based on styrene–butadiene‐block–copolymers: Microstructural characterization
Authors: Acosta J. L. , González L. , Del Río C. , Ojeda C. , Rodríguez A.
Published: October 2004

This work reports on the preparation and structural and electrical characterization of composites consisting of HSBR, polypropylene (PP), and carbon black (CB) blends, comparing the data obtained from more or less rich PP samples. Structural analysis provided evidence of the plasticizing or crosslinked effects on the properties of composites, when CB is present in the initial system, as well as of the excellent conducting properties of CB composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 646–653, 2002; DOI 10.1002/app.10360
Interdiffusion in a particle matrix system of two miscible polymers: An investigation by positron annihilation lifetime spectroscopy and differential scanning calorimetry
Authors: Dlubek G. , Taesler C. , Pompe G. , Pionteck J. , Petters K. , Redmann F. , Krause‐Rehberg R.
Published: October 2004

Positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetry (DSC) were used to study the interdiffusion in a particle matrix system consisting of (styrene‐maleic anhydride) copolymer containing 24% maleic anhydride (SMA) and poly(methyl methacrylate) (50:50). Starting from the phase separated state of the miscible components, the transition to the mixed state due to interdiffusion during annealing at 160 and 180 °C was investigated. The diffused mass fractions of both components were estimated by DSC; they increase linearly with the logarithm of the annealing time. Both components show the same behavior, suggesting an average interphase composition of 50:50. For subsequent annealing, the kinetic behavior differs from the earlier behavior, probably because of the different diffusion coefficients of the two components. Experimental evidence is presented that the ortho‐positronium (o‐Ps) intensity correlates to the interdiffusion process. The response is due to the diffusion of inhibitors for Ps formation from one phase into the other. A semiquantitative model is developed that allows the estimation of the interphase volume fraction from the relative change of the annihilation parameters. The PALS results are discussed in relation to those obtained by DSC. The results show that PALS is a useful tool to study mixing and demixing processes in polymer blends with a three‐dimensional morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 654–664, 2002; DOI 10.1002/app.10362
Miscibility, melting, and crystallization of poly(trimethylene terephthalate)/poly(ether imide) blends
Authors: Huang Jieh‐Ming , Chang Feng‐Chih
Published: October 2004

Miscibility, melting, and crystallization behaviors of solution‐blended poly(trimethylene terephthalate) (PTT)/poly(ether imide) (PEI) blends have been investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and polarized light microscopy (PLM). These blends show a single and composition‐dependent glass transition temperatures over the entire composition range, implying that these blends are fully miscible in the amorphous region. The enthalpy of the middle endotherm melting of the primary crystallization decreases with increasing PEI content in the blend. Recrystallization of PTT during heating scan in DSC is either retarded or fully inhibited by the presence of PEI. In nonisothermal crystallization, the depression of crystallization temperature of PTT also depends on the blend composition and cooling rate; the presence of PEI decreases the PTT segments migrating to the crystallite‐melt interface. The effects of temperature and PEI content on the spherulite growth rate of PTT were evaluated by PLM. The spherulite growth rate decreases with the increase of the PEI content, implying that it is a thermodynamically dominant process. Both thermodynamic and kinetic factors cause total inhibition of PTT crystallization at higher PEI content in the blend. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 850–856, 2002; DOI 10.1002/app.10367
Resolving lateral variations in the frequency dependence of adhesive properties at the surface of a model pressure sensitive adhesive
Authors: Jia Shijun , Foster Mark D.
Published: October 2004

A commercial scanning probe microscope may be used to laterally resolve qualitative differences in the frequency dependence of material properties at the surface of a model pressure sensitive adhesive (PSA). In a heterogeneous PSA made from polyisoprene and a wood rosin derivative, both the polymer‐rich matrix and tackifier‐rich domains regions at the surface appear stiffer and show higher adhesive force when increasing the testing frequency from 0.01 to 1 Hz at room temperature. The limited frequency range of the instrument and piezo creep constrain the applicability of the approach. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 400–404, 2002; DOI 10.1002/app.10369
Semiempirical rate equation for solid state polymerization of poly(ethylene terephthalate)
Authors: Duh Ben
Published: October 2004

Solid‐state polymerization (SSP) of poly(ethylene terephthalate) (PET) is characterized by two distinct features. First, there exists an ultimate or limiting intrinsic viscosity (IV). Second, the SSP rate varies with the prepolymer IV. Although there are several existing empirical rate equations and numerous published models for the SSP of PET, none can adequately describe these features. In this article, a simple semiempirical rate equation that aptly describes the behaviors of the SSP of PET is proposed. It is based on the assumptions that there are two categories of functional end groups, active and inactive end groups, and that the overall SSP follows a second order kinetics. Thus, the overall SSP rate is expressed as −dC/dt = 2 ka (C − Cai)2, where C is the total end group concentration, t, the SSP time, ka, the apparent reaction rate constant, and Cai, the apparent inactive end group concentration. With this rate equation, the effects of all factors that influence the SSP rate are implicitly and conveniently accounted for by the two parameters, ka and Cai. For example, ka increases, while Cai decreases, with increasing SSP temperature, increasing prepolymer IV, and decreasing particle size. The proposed rate equation fits the IV or molecular weight build‐up curves for the SSP of PET under various conditions very well, and can be extrapolated beyond data with reasonable accuracy. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 857–870, 2002; DOI 10.1002/app.10370
Flocculation of montmorillonite by some hydrophobically modified polycations containing quaternary ammonium salt groups in the backbone
Authors: Dragan Stela , Maftuleac Alexei , Dranca Ion , Ghimici Luminita , Lupascu Tudor
Published: October 2004

The flocculating efficiency of some hydrophilic/hydrophobic cationic polyelectrolytes on montmorillonite suspension in water was investigated as a function of both the polycation structure and the flocculation parameters: polycation/montmorillonite contact time, suspension pH, polycation dose, and temperature. Cationic polyelectrolytes with quaternary ammonium salt groups in the backbone and hydrophobic side chains (hexyloxypropyl, PCA5H1 and PCA5H2; and decyloxypropyl, PCA5D1, respectively) were used as flocculants. The flocculation was time dependent. A negative influence of the stirring time and of the abrupt variation of pH from basic to acidic on the separation efficiency was evidenced. The increase of the polycation dose from 0.58 mg polycation/g montmorillonite up to 1.74 mg/g montmorillonite showed a positive influence on the sedimentation of montmorillonite particles for all the polycations taken into account. The influence of the polycation structure was reflected in the lower turbidity found in the case of the polycation PCA5D1 compared with that of PCA5H1, at the same concentration; this reflects the positive influence of the hydrophobicity increase on the suspension separation. A common characteristic for all the polycations is that, for more than about 60 min of settling, the lowest turbidity was found at 25°C and the highest at 5°C. The turbidity found at 15°C was in between, both before and after 60 min of settling time. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 871–876, 2002; DOI 10.1002/app.10371
Rheological study of polypropylene copolymer/polyolefinic elastomer blends
Authors: Paul Subhasish , Kale D. D.
Published: October 2004

Blends of polypropylene copolymer (PP‐cp) and a polyolefinic elastomer (POE) were prepared by a melt‐blending process at 210°C and 60 rpm using a counterrotating twin‐screw extruder. The POE content was varied up to 25%. The shear viscosity over a wide range of shear rate was measured. All blend compositions showed well‐defined zero shear viscosity and shear thinning behavior. The melt viscosity values were between those of the principal components in all cases. Rheology of blends shows different behavior up to concentrations of POE corresponding to the tough–brittle transition. The linear viscoelastic properties (G′, G″, η*, η′, η″) were used to check the miscibility of the two components in the melt state. All blend compositions showed a good degree of miscibility over the range of POE concentrations studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 665–671, 2002; DOI 10.1002/app.10376
Effect of doping polyacrylic acid with some dopants as studied by different techniques
Authors: Mostafa N. , Mohamed Manal G.
Published: October 2004

The molecular weight of polyacrylic acid (PAA) was determined by a viscometric method using NaNO3 as solvent at 30°C. The specific electric conductivities (σ) of PAA as well as PAA doped with carbon black (CB), chromium oxide (Cr2O3), and cupferron with different concentrations (from 0.25 to 1 wt %) were measured at a temperature range 360–400 K. IR spectra of some polymers were determined and it was shown that when PAA was doped with 0.5 wt % CB, a COC band appeared at 775–875 cm−1. The positron annihilation lifetime (PAL) spectra in PAA doped with the above‐mentioned dopants were measured as a function of their concentrations. It was observed that the short lifetime intensity I1 decreased, whereas the intermediate lifetime intensity I2, which is related to the conductivity of the material, increased with increasing the wt % of Cr2O3 and cupferron as well as at low concentrations of CB. These results are discussed in terms of the conducting island model. It was found that there were distinct positive relationships between σ and I2. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 877–883, 2002; DOI 10.1002/app.10381
Effect of preparation method on the capture and release of biologically active molecules in chitosan gel beads
Authors: Ghanem Amyl , Skonberg Denise
Published: October 2004

Model bioactive compounds with different molecular and functional characteristics were entrapped in gel beads prepared by polyelectrolyte complexation of chitosan and pentasodium tripolyphosphate (TPP). Three compounds of interest to the food and biomedical industries were tested: (1) lysine, (2) bovine serum albumin (BSA), and (3) β‐galactosidase. Effects of the compound concentration in the initial chitosan solution, pH of the curing solution, and length of the curing phase on the capture efficiency were evaluated. Release rates for lysine and BSA into a phosphate buffer, distilled water, and a synthetic ocean solution were observed, and the activity of the entrapped β‐galactosidase was determined. The capture efficiencies for lysine and BSA decreased as the concentration increased. The capture efficiency for lysine ranged from 90% at pH 5 to 20% at pH 8.6. There was no significant effect of the release media on the rate of release. BSA and lysine release reached 90% of the maximum after 100 and 50 min, respectively. The capture efficiency of β‐galactosidase was not affected by the pH of TPP; however, enzyme activity in the beads decreased as the pH increased. Beads prepared in the pH 8.6 TPP solution had significantly higher rates of enzyme release over time. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 405–413, 2002; DOI 10.1002/app.10393
Cellulose acetate and sulfonated polysulfone blend ultrafiltration membranes. II. Pore statistics, molecular weight cutoff, and morphological studies
Authors: Malaisamy R. , Mahendran R. , Mohan D.
Published: October 2004

The determination of the pore size, porosity, number of pores, molecular weight cutoff (MWCO), and morphology of an ultrafiltration membrane is necessary for predicting the performance of a membrane for a specific application. For ultrafiltration membranes prepared from cellulose acetate and sulfonated polysulfone in the presence and absence of various concentrations of the additive poly(ethylene glycol) 600, pore statistics and MWCOs were determined in studies with dextrans of different molecular weights. Surface and cross‐sectional morphologies of the membranes were analyzed with scanning electron microscopy at different magnifications. The pore size increased with increasing concentrations of sulfonated polysulfone and additive in the casting solution. Similarly, the MWCOs of the membranes ranged from 19 to 150 kDa, depending on the various polymer blend compositions and additive concentrations. Results from scanning electron microscopy provided qualitative evidence for the trends observed for the pore statistics and MWCO results. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 430–444, 2002; DOI 10.1002/app.10414