bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of clay on immiscible morphology of poly(butylene terephthalate)/polyethylene blend nanocomposites
Authors: Wu Defeng , Zhou Chixing , Zhang Ming
Published: August 2006

Polymer blend nanocomposites containing poly(butylene terephthalate) (PBT), polyethylene (PE), and organoclay were prepared by direct melt compounding. Their immiscible morphologies weree investigated using electronmicroscopy, X‐ray diffraction, and parallel plate rheometry. The PE domain sizes were reduced when the polar PBT phase was continuous (PBT/PE = 60/40) because the clay tactoids effectively prevented the coalescence of the dispersed PE domains. However, when the PBT component presented domains dispersed in the rich PE matrix (PBT/PE = 40/60), the addition of clay (>2 wt %) changed the phase morphology into a novel cocontinuous one, which was further confirmed by rheological measurements. The existence of clay tactoids led to a sharp enhancement in the viscosity of the PBT phase, changing the viscosity ratio between the PBT and PE phases remarkably, which may have promoted the phase inversion. As a result, clay had significant effects on the morphology of the polymer blend. © 2006 Wiley Periodicals Inc. J Appl Polym Sci 102: 3628–3633, 2006
Hydrogel‐forming agar‐graft‐PVP and κ‐carrageenan‐graft‐PVP blends: Rapid synthesis and characterization
Authors: Prasad Kamalesh , Mehta Gaurav , Meena Ramavatar , Siddhanta A. K.
Published: August 2006

Grafting of agar and κ‐carrageenan with polyvinylpyrrolidone (PVP, average molecular weight 10,000 D) in an aqueous medium at a pH of about 7 produced agar‐graft‐PVP and κ‐carrageenan‐graft‐PVP blends capable of forming hydrogels. The reaction was carried out with microwave irradiation in the presence of a water‐soluble initiator, potassium persulfate. Optimum microwave irradiation conditions for obtaining hydrogels of the grafted products were achieved. The structural characteristics and thermal stability of the grafted blends were studied by Fourier transform infrared, 13C‐NMR, and thermogravimetric analyses. Appearance of new IR bands at 1661, 1465, and 1426 cm−1 in the grafted products indicated the insertion of PVP into the polysaccharide structure. Powder X‐ray diffraction studies revealed the enhanced crystallinity in the products compared to in the control polysaccharides as well as PVP. Agar and κ‐carrageenan were grafted to a considerable degree, with 62.5 E % and 125 G % for agar‐graft‐PVP and 65.5 E % and 131 G % for κ‐carrageenan‐graft‐PVP. Optical micrographs of the grafted blends indicated considerable changes in the morphology of the agar and the κ‐carrageenan, substantiating the X‐ray diffraction data. A plausible mechanism for the crosslinking of PVP to agar and κ‐carrageenan is proposed. These hydrogels exhibited enhanced water‐holding capacity despite weaker gel strength than that in the respective control polysaccharides. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3654–3663, 2006
Pseudoreinforcement effect of multiwalled carbon nanotubes in epoxy matrix composites
Authors: Zhuang G. S. , Sui G. X. , Sun Z. S. , Yang R.
Published: August 2006

The carbon nanotube possesses outstanding physical properties. Theoretically, adding carbon nanotubes into a polymer matrix can remarkably improve the mechanical properties of the polymer matrix. In the present work, a series of composites was prepared by incorporating multiwalled carbon nanotubes (MWNTs) into an epoxy resin. The influences of MWNT content and curing temperature on the flexural properties of the epoxy resin were investigated. The results showed that a very low MWNT content should be used to ensure homogeneous dispersion of MWNTs in the epoxy matrix. A higher MWNT content may lead to deteriorated mechanical properties of the composites because of the aggregation of MWNTs. A decline in the flexural properties of the neat epoxy resin with increasing curing temperature was found. However, under the same curing conditions, improvement in flexural properties was observed for the composite with the low MWNT content and a mild curing temperature. The improvement was far beyond the predictions of the traditional short‐fiber composite theory. In fact, this improvement should be attributed to the retarding effect of MWNTs on the curing reaction of epoxy matrix. Therefore, the improvement in the flexural properties was only a pseudoreinforcement effect, not a nano‐reinforcement effect of the MWNTs on the epoxy resin. Perhaps, it is better for MWNTs to be used as functional fillers, such as electrical or thermal conductive fillers, than as reinforcements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3664–3672, 2006
A novel method to prepare a metallocene adduct catalyst with low moisture sensitivity
Authors: Wang Hongtao , Chen Wei , Zheng Gang , Li Hangquan
Published: August 2006

A novel method to prepare a three‐constituent adduct of metallocene Cp2MCl2/2LiCl/THF is proposed. The adduct catalyst can be easily prepared without salt separation and recrystallization and possessed a low moisture sensitivity and a high stability. Measurements with NMR and XPS showed that specific intermolecular interactions exist among the three components, by which the stability of the adduct was increased. The activity of the catalyst was evaluated in the polymerization of ethylene. The kinetic behavior was also studied. It showed a high reservation of activity even when exposed to a high relative humidity for hours. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3944–3948, 2006
Effect of miscibility and forced compatibility on damping properties of CIIR/PAc blend
Authors: Su Huang Guang , Ru He Xiang , Rong Wu Jing , Ying Pan Qi , Zhen Jing , Hong Zhuo
Published: August 2006

In this study, a kind of novel damping materials was prepared based on the blend of chlorinated butyl rubber (CIIR) and polyacrylate (PAc) synthesized by different molar ratio of butyl methacrylate and ethyl acrylate. Research results from experiments and analyses by employing DMA, TEM, and FTIR show that whether at a cocured system or noncocured system, it can be achieved to shift a loss peak of CIIR towards a higher temperature region and to keep the damping value from markedlly decreasing, which broadens the effective damping function area of CIIR to the vicinity of ambient temperature. In the former system, the thermodynamical miscibility of CIIR and PAc, to some extent, is predominated by the molecular design of PAc, while in the latter system, covulcanized networks play a more significant role in improving compatibility and abating the peak split, though the suppression effect of thermal stress on the transition of CIIR Tll transition still can not be neglected. Furthermore, transition state derived from the cocuring CIIR and PAc cannot make the phase separation completely take place, and consequently results in the deformation of phase morphology of the cocured CIIR/PAc blend. It is the influence of thermodynamics miscibility and forced compatibility in different size that makes the suppression effect of foreign PAc on CIIR Tll transition be controllable. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3127–3133, 2006
Compatibilization of PP/EPDM blends by grafting acrylic acid to polypropylene and epoxidizing the diene in EPDM
Authors: Ao Y. H. , Sun S. L. , Tan Z. Y. , Zhou C. , Zhang H. X.
Published: August 2006

In this article, ethylene–propylene–diene‐rubber (EPDM) was epoxidized with an in situ formed performic acid to prepare epoxided EPDM (eEPDM). The eEPDM together with the introduction of PP‐g‐AA was used to compatibilize PP/EPDM blends in a Haake mixer. FTIR results showed that the EPDM had been epoxidized. The reaction between epoxy groups in the eEPDM and carboxylic acid groups in PP‐g‐AA had taken place, and PP‐g‐EPDM copolymers were formed in situ. Torque test results showed that the actual temperature and torque values for the compatibilized blends were higher than that of the uncompatibilized blends. Scanning electron microscopy (SEM) observation showed that the dispersed phase domain size of compatibilized blends and the uncompatibilized blends were 0.5 and 1.5 μm, respectively. The eEPDM together with the introduction of PP‐g‐AA could compatibilize PP/EPDM blends effectively. Notched Izod impact tests showed that the formation of PP‐g‐EPDM copolymer improved the impact strength and yielded a tougher PP blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3949–3954, 2006
Developing protective textile materials as barriers to liquid penetration using melt‐electrospinning
Authors: Lee Seungsin , Kay Obendorf S.
Published: August 2006

Electrospun polypropylene fiber webs and laminates were developed using melt‐electrospinning, to explore an alternative way of manufacturing protective clothing materials for agricultural workers. Electrospun polypropylene webs were fabricated in two levels of thickness. To examine the effect of lamination on the protection/thermal comfort properties, the webs were laminated on nonwoven fabric substrates. Barrier performance was evaluated for the electrospun webs and laminates, using two pesticide mixtures that represent a range of surface tension and viscosity. Effects of web thickness and lamination on air permeability and water vapor transmission were assessed as indications of thermal comfort performance. Penetration testing shows that electrospun polypropylene webs provide excellent barrier performance against the high surface tension challenge liquid, whereas the laminated fabrics of electrospun polypropylene webs exhibited performance of 90–100% for challenge liquids with varying surface tension. Air permeability of electrospun polypropylene webs decreased by ∼20% because of the lamination and web thickness, but was still higher than most of the materials currently in use for protective clothing. Water vapor transmission of electrospun polypropylene webs reduced by up to 12% from the lamination and web thickness as well, but was still in a range comparable to woven work clothing fabrics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3430–3437, 2006
Dispersion copolymerization of acrylamide with acrylic acid in an aqueous solution of ammonium sulfate: Synthesis and characterization
Authors: Liu Xiaoguang , Chen Dongnian , Yue Yumei , Zhang Wende , Wang Pixin
Published: August 2006

Dispersion copolymerization of acrylamide with acrylic acid in an aqueous solution of ammonium sulfate using poly(2‐acrylamido‐2‐methylpropanesulfonic acid sodium) as the stabilizer and ammonium persulfate (APS) as the initiator was investigated. The influence of initiator concentration, stabilizer concentration, ammonium sulfate concentration, chain‐transfer agent concentration, and polymerization temperature on the copolymerization was discussed. The results showed that varying the ammonium sulfate concentration could affect the particle size and the intrinsic viscosity of the copolymer significantly. With increasing the stabilizer concentration, the particle size of the copolymer decreased first, and then increased, meanwhile the intrinsic viscosity of the copolymer decreased. The increase of initiator concentration, chain‐transfer agent concentration, and polymerization temperature resulted in the increase in the particle size. Polydisperse spherical particles were formed in the system, and the kinetics for the dispersion copolymerization were discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3685–3690, 2006
Rheological properties in blends of poly(aryl ether ether ketone) and liquid crystalline poly(aryl ether ketone)
Authors: Chen Jian , Liu Xincai , Yang Decai
Published: August 2006

Rheological properties of the blends of poly(aryl ether ether ketone) (PEEK) with liquid crystalline poly(aryl ether ketone) containing substituted 3‐trifluoromethylbenzene side group (F‐PAEK), prepared by solution precipitation, have been investigated by rheometer. Dynamic rheological behaviors of the blends under the oscillatory shear mode are strongly dependent on blend composition. For PEEK‐rich blends, the systems show flow curves similar to those of the pure PEEK, i.e., dynamic storage modulus G′ is larger than dynamic loss modulus G″, showing the feature of elastic fluid. For F‐PAEK‐rich systems, the rheological behavior of the blends has a resemblance to pure F‐PAEK, i.e., G″ is greater than G′, showing the characteristic of viscous fluid. When the PEEK content is in the range of 50–70%, the blends exhibit an unusual rheological behavior, which is the result of phase inversion between the two components. Moreover, as a whole, the complex viscosity values of the blends are between those of two pure polymers and decrease with increasing F‐PAEK content. However, at 50% weight fraction of PEEK, the viscosity‐composition curves exhibit a local maximum, which may be mainly attributed to the phase separation of two components at such a composition. The changes of G′ and G″ with composition show a trend similar to that of complex viscosity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4040–4044, 2006
Adjustable temperature sensor with double thermoresponsiveness based on the aggregation property of binary diblock copolymers
Authors: Wu Kai , Shi Linqi , Zhang Wangqing , An Yingli , Zhu Xiao‐Xia
Published: August 2006

This article presents a new and promising way to design a temperature sensor, which is based on the micellization or aggregation behavior of binary diblock copolymers of poly(ethylene glycol)‐b‐poly(N‐isopropylacrylamide) (PEG‐b‐PNIPAM) and poly(ethylene glycol)‐b‐poly(4‐vinylpyridine) (PEG‐b‐P(4‐VP)). The temperature sensor presents both a lower critical response temperature (LCRT) and an upper critical response temperature (UCRT), where the thermoreversible aggregating of PEG‐b‐P(4‐VP) and H2SO4 is used to control the LCRT, and the thermoreversible micellization of PEG‐b‐PNIPAM is used to control the UCRT. Furthermore, the LCRT can be altered by changing the H2SO4 concentration, and the UCRT can be adjusted by altering the PEG‐b‐PNIPAM concentration. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3144–3148, 2006
A new and simple way of preparing polycation‐grafted fibrous cellulose
Authors: Roche Philippe
Published: August 2006

A new way of producing polycation‐grafted fibrous cellulose for its use as a retention aid in the papermaking process was conceived. It consists of adding, under intense stirring, to a cellulose fibers suspension at a basic pH a cationic polyacrylamide dissolved in water. As the cellulose fiber's surface is negatively charged because of its more or less acid groups, the cationic polymer adsorbs on it. The cationic‐grafted cellulose fibers are very similar to the cellulose fibers used in papermaking, since the polymer is (on a micrometer scale) homogeneously grafted on them as a film. It could so be used to increase the retention of the negatively charged fillers, fibers, and pigments during the process, without altering the properties of the resulting sheet of paper. The amount of polymeric grafts depends on the quantity of anionic groups on fiber's surface and varies monotonically with the grafting temperature and polyacrylamide's concentration in the blend. The grafted fibrous cellulose is well stable, even in drastic media and for lower Mw grafts, and the amount of grafted polymer also depends on the concentration and characteristics of fiber's suspension. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3149–3157, 2006
Thermal and dynamic mechanical characterization of polyurethane–urea–imide coatings
Authors: Mishra Aswini K. , Chattopadhyay D. K. , Sreedhar B. , Raju K. V. S. N.
Published: August 2006

A series of NCO terminated polyurethane (PU)–imide copolymers were synthesized by a systematic three‐step process and were chain extended with different diol/diamine chain extenders. In the first step, isocyanate terminated PU prepolymers were prepared by reacting soft segments such as polyester (PE) polyols and polyether polyols such as polypropylene glycol (PPG‐1000) with hard segments like 2,4‐tolylene‐diisocyanate (TDI) or isophorone‐diisocyanate (IPDI) with NCO/OH ratio 2:1. In the second step, thermally stable heterocyclic imide ring was incorporated using isocyanate terminated PU prepolymers by reacting with pyromellitic dianhydride (PMDA) in a excess‐NCO:anhydride ratio of 1:0.5. The surplus NCO content after imidization was both moisture cured or partially reacted with chain extender and moisture cured. The films were characterized by thermogravimetric (TG), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) instruments. The adhesion strength of these coatings on mild steel (MS), copper (Cu), and aluminum (Al) is dependent on the nature of the substrate. The TGA analysis show good thermal stability. The DMTA results show the microphase separation between the different hard and soft segments. Finally, a structure to property correlation was drawn based on the structure of the soft, hard, and chain extender and the observed properties are useful for understanding and design of intelligent coatings. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3158–3167, 2006
Study of piezo‐damping properties of CPE/ZKF/VGCF composites
Authors: Ding Xin Bo , Yan Xiong
Published: August 2006

The electrical and damping behaviors of chlorinated polyethylene (CPE)/2,2′‐methylene‐bis‐(4‐methyl‐6‐cyclohexylphenol) (ZKF)/vapor‐grown carbon fiber (VGCF) have been investigated. CPE/ZKF/VGCF systems exhibit typical percolation characteristics of filled conductive polymer composites. For CPE/ZKF/VGCF composites, dynamic mechanical analysis (DMA) shows that, at the glass transition temperature (Tg) of CPE/ZKF system, the values of loss factor increase with the increasing VGCF content. Within the temperature range of 60–75°C, the values of loss factor for CPE/ZKF/VGCF samples are higher than that of CPE/ZKF and present a peak at 16 vol% VGCF content. This implies that the piezo‐damping effect is directly related to the conductive network formation in the composites, and the piezo‐damping effect can be regulated by regulating the VGCF content. Therefore, the composite of CPE/ZKF/VGCF is a good damping material with a high and broad loss factor that can be regulated according to practical applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3181–3185, 2006
Model of liquid permeability in swollen composites of superabsorbent polymer and fiber
Authors: Buchholz Fredric L.
Published: August 2006

The liquid permeability of composites of fiber and superabsorbent polymer (SAP) is critical to the proper performance of absorbent hygiene products such as infant diapers. Previous work has focused on empirically improving performance of absorbent composites by modifying the components, but a systematic study of the parameters affecting permeability of these systems has not been published. A good model of permeability would aid our understanding of the complex phenomenon of liquid permeability of pads that change in volume and porosity during swelling. In the present work, a mathematical model of liquid permeability in both gel beds and composites of fiber and gel is developed. The model uses a Carman–Kozeny approach with added calculation of the porosity and specific surface area that result upon swelling of the SAP, as well as subsequent compression of the swollen composite. The model incorporates ten parameters that are necessary to determine the permeability of the system. The implications of the model for improving permeability in absorbent composites are explored. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4075–4084, 2006
Rheological investigation of the influence of acrylate polymers on the modification of asphalt
Authors: Iqbal Mohammad H. , Hussein Ibnelwaleed A. , Wahhab Hamad I. Al‐Abdul , Amin Mohamed B.
Published: August 2006

The effect of ethylene, ethylene acrylate and glycidyl methacrylate (EA) terpolymer, and ethylene butyl acrylate (EBA) copolymer on asphalt modification was investigated at 4, 6 and 8% polymer concentrations. Both melt state rheology and asphalt concrete mix (ACM) were investigated. In the melt state analysis, dynamic shear rheology, storage stability, artificial ageing, and performance grading (PG) were studied. The PG grading of polymer modified asphalt (PMA) is correlated to the elastic properties of the polymers. Both resins improved the rheological properties, reduced the temperature susceptibility, showed better storage stability, and increase the upper grading (performance) temperature of the base asphalt. The two polymers showed similar ageing characteristics with little influence on flow activation energy. In asphalt concrete mix analysis, Marshall stability, stripping (durability), resilient modulus, and permanent deformation tests were performed. Polymer‐modified asphalt concrete mix (PMACM) has increased percent retained stability and the resilient modulus when compared with ACM. The elastic modulus of PMA and the resilient modulus of their ACM followed the same trend. Weak influence on water sensitivity was observed, but excellent rutting resistance was obtained for PMACM over ACM. EA (much cheaper than EBA) produced satisfactory properties of PMA and superior ACM properties when blended with the high asphaltenes Arabian asphalt. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3446–3456, 2006
Characterization of mold fouling during elastomer injection molding
Authors: Hornsby Peter R. , Singh Inderjeet , Daley John R. , Firth John
Published: August 2006

Consideration is given to the characterization and origins of mold fouling occurring during the injection molding of elastomers. Results for nitrile rubber and fluoroelastomer compounds are presented with a range of techniques, including light microscopy, scanning electron microscopy, elemental analysis by energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron spectroscopy, and surface‐energy measurements with the sessile drop approach. A specially designed mold tool combined with interchangeable cavity inserts has also enabled the exploration of the effects of different metal surface treatments on the onset and extent of mold fouling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3186–3194, 2006
Synthesis and characterization of poly(aryl ether sulfone)s with metallophthalocyanine pendant unit
Authors: Zhang Yunhe , Niu Yaming , Xu Rui , Wang Guibing , Jiang Zhenhua
Published: August 2006

A series of novel poly(aryl ether sulfone) copolymers containing dicyanophenyl group were prepared by the reaction of bis(4‐chlorophenyl)sulfone with (3,4‐dicyano) phenylhydroquinone and 4,4′‐isopropylidenediphenol. On this basis, a series of poly(aryl ether sulfone)s containing metallophthalocyanine units were synthesized by the reaction of poly(aryl ether sulfone)s containing dicyanophenyl group with excessive amounts of 1,2‐dicyanobenzene and the corresponding metal salt in quinoline. All these copolymers were found to have high glass transition temperature and thermal stability. These copolymers were found to be soluble in common solvents, and capable of forming transparent films by solution casting. The copolymers containing metallophthalocyanine units showed strong optical absorption in the visible region, and exhibited blue photoluminescence in solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3457–3461, 2006
Synthesis of copolymeric hydrogels using gamma radiation and their utilization in the removal of some dyes in wastwater
Authors: Abdel‐Aal Samia E.
Published: August 2006

Copolymer hydrogels were prepared by γ‐radiation copolymerization of maleic acid (MA) and 2‐hydroxyethylacrylate (HEA) or acrylamide (AAm). The effect of AAm/MA and HEA/MA composition and irradiation dose on the gel fraction yield in the prepared hydrogels was determined. It was found that as the content of MA increased, the gel fraction yield decreased. The increase of irradiation dose resulted in increasing the crosslinked network structure and consequently the gel percent. The parameters of equilibrium swelling, maximum swelling, initial swelling rate, diffusion exponent, and diffusion coefficient of the hydrogels were calculated and evaluated, and it was found that water diffusion to the hydrogels generally was a non‐Fickian diffusion type. Characterization of the prepared hydrogels was studied and accordingly the possibility of its practical use in the treatment of waste dyes from aqueous solution was studied. The effect of treatment time, the pH of the feed solution, initial feed concentration, and temperature on the dye uptake was also investigated. The maximum uptake of the investigated dyes was higher for HEA/MA hydrogel than that for AAm/MA hydrogel. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3720–3731, 2006
Mechanical properties and release studies of chitosan films impregnated with silver sulfadiazine
Authors: Azevedo Eduardo P. , Saldanha Tásia D. P. , Navarro Marco V. M. , Medeiros Aldo C. , Ginani Marconi F. , Raffin Fernanda N.
Published: August 2006

The purpose of these studies was to evaluate chitosan films impregnated with silver sulfadiazine as potential wound dressings, based on their mechanical properties and the controlled‐release phenomenon. The mechanical properties of such films were investigated under varying plasticizers (glycerol or sorbitol) concentrations, as well as in the presence of a crosslinking agent (formaldehyde). The drug release was also determined under such varying conditions, as well as using different thicknesses of film and drug concentrations. The results showed that the additives decreased the tensile strength of the chitosan films (except for sorbitol at 20% w/w), while at the same time remarkably enhancing the percentage elongation of the films. This elongation was especially pronounced in the case of glycerol. The type of plasticizer also influenced the release of silver sulfadiazine. Glycerol had a greater effect than sorbitol on the release rate, regardless of the amount used, probably due to leakage of this additive from the film, which leaves pores that enhance the water uptake of the film. As might be expected, increased concentrations of entrapped silver sulfadiazine yielded increasingly higher release rates. Decrease in thickness of the film also enhanced the release rate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3462–3470, 2006
Supercritical carbon dioxide‐assisted dispersion of sodium benzoate in polypropylene and crystallization behavior of the resulting polypropylene
Authors: Li Bin , Hu Guo‐Hua , Cao Gui‐Ping , Liu Tao , Zhao Ling , Yuan Wei‐Kang
Published: August 2006

This work aimed at studying the efficiency of the use of supercritical carbon dioxide (scCO2) as a swelling agent to disperse sodium benzoate (NaBz), a nucleating agent, in polypropylene (PP), on the one hand; and the crystallization behavior of the resulting PP, on the other hand. Under scCO2, the NaBz was uniformly dispersed in the PP at a nanometer scale. The use of ethanol or acetone as a cosolvent further increased its state of dispersion and its mass uptake in the PP. Isothermal and nonisothermal crystallization kinetics indicated that the PP with the NaBz being dispersed in it under scCO2 had a much higher crystallization rate than that of the pure PP or the PP with the NaBz being dispersed in it by a conventional melt compounding process. The size of the PP crystallites was also much smaller when the NaBz was dispersed at a nanometer scale. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3212–3220, 2006
Investigation on gradient dielectric characteristics of bamboo (Dendrocalamus strictus)
Authors: Chand Navin , Jain Deepak , Nigrawal Archana
Published: August 2006

Dielectric constant (ε′) and tan δ dependence on distance from the outer most skin to the center of bamboo has been determined. Dielectric measurements have been done in the temperature range from 24 to 120°C and in the frequency range from 4 to 100 kHz. Gradient behavior in dielectric constant (ε′) and tan δ has been found in bamboo. It has also been observed that the dielectric constant (ε′) and tan δ increase with the increasing temperature and decrease with the increasing frequency. Relaxation times have been calculated for the four samples at 80, 90, and 100°C temperatures, which show that relaxation time decreases with the increase of temperature due to the increased molecular mobility. A continuous increase in the hardness from the center 48 to the outer surface 70 and density from 0.45 to 0.80 g/cc has been observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3489–3494, 2006
Degradation of chitosan and chemically modified chitosan by viscosity measurements
Authors: Agnihotri Sunil A. , Kulkarni Vaibhav D. , Kulkarni Anandrao R. , Aminabhavi Tejraj M.
Published: August 2006

Chitosan and chitosan‐grafted‐acrylamide were subjected to degradation in the presence and absence of a degrading agent at 37°C by measuring the viscosity of polymer solutions. Extracts from the fresh rat droppings were used as the degrading agent to simulate the environmental degrading conditions. Results of this study indicated that the concentrations of acetic acid in solution and chemical modifications of chitosan affected the degradation both in the presence as well as in the absence of a degrading agent. Reduction in viscosity was used to study the degradation. Chitosan was stable up to sixteen days of immersion in acetic acid without the degrading agent, but it readily underwent degradation in the presence of a degrading agent. Chitosan‐grafted‐acrylamide also followed the same trend, but the extent of reduction in viscosity was much less than pure chitosan, indicating that the chemical modification has improved the stability of the polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3255–3258, 2006
Property and reliability of liquid underfill material for IC packaging
Authors: Chiu Hsien‐Tang , Chung Jung‐Sheng
Published: August 2006

Thermoplastic nylon powder was added to naphthalene epoxy to serve as a stress release agent to reduce the stress resulting from the shrinkage during the cure of naphthalene epoxy. The purpose of this study was to explore the physical impact and effect on the forming object after adding nylon powder onto naphthalene epoxy. Mechanical properties were explored through the Izod impact test, the three‐point bending test, tensile test, and lap shear adhesion test. Thermal mechanical analysis (TMA) and dynamic mechanical analysis (DMA) were conducted to identify the coefficient of thermal expansion (CTE) and the glass transition temperature (Tg). The rate of water absorption was measured via a test of pressure cook test (PCT), and insulation resistance was assessed through the breakdown voltage experiment. The results indicate that the addition of nylon powder increases the fracture energy of the cured epoxy; however, mechanical properties (lap shear strength, flexural strength, tensile strength) decreased slightly. The TMA and DMA results showed that the CTE (α1) decreased when nylon was added and the heat resistance decreased a little. The water absorption rate test and PCT showed that the rate of water absorption increased to a small extent, whereas the breakdown voltage decreased slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3504–3509, 2006
Kinetics of the anionic ring‐opening polymerization of octamethylcyclotetrasiloxane initiated by potassium isopropoxide
Authors: Zhang Yong , Zhang Zhijie , Wang Qian , Xie Zemin
Published: August 2006

Kinetics of the anionic ring‐opening polymerization of octamethylcyclotetrasiloxane (D4) in bulk initiated by potassium isopropoxide was studied. Several promoters includingN‐methyl‐2‐pyrrolidinone (NMP),N,N‐dimethylformamide (DMF), and diglyme were used. It is indicated that the reactions are first‐order in D4during the initial stage of polymerization. The polymerization rate of D4is influenced by a number of factors, such as the nature of promoters, the molar ratio of promoter to initiator (Cp/Ciratio), and the reaction temperatures. With the use of NMP as promoter, the polymerization rate constant at 30°C is 10.482 h−1with theCp/Ciratio equal to 3.0. As theCp/Ciratio increases, the polymerization rate constant increases sharply and the cyclic oligomers content in polymer decreases evidently. The back‐biting reaction that leads to the formation of decamethylcyclopentasiloxane (D5) occurred in the polymerization of D4. The rate of the D5formation relatively to the rate of D4conversion increases with the conversion of D4. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3510–3516, 2006
Effects of ultrasound on the synthesis and properties of polyurethane foam/clay nanocomposites
Authors: Seo W. J. , Sung Y. T. , Kim S. B. , Lee Y. B. , Choe K. H. , Choe S. H. , Sung J. Y. , Kim W. N.
Published: August 2006

Polyurethane foam (PUF)/clay nanocomposites were synthesized with clay modified by polymeric 4,4′‐diphenylmethane diisocyanate (PMDI) with the application of ultrasound. Transmission electron micrographs showed that the interlayer distance increased for the polyurethane (PU)/clay nanocomposites where ultrasound was applied. The results of the transmission electron microscopy and X‐ray measurements suggest that the application of ultrasound to the clay modification with PMDI improved the efficiency of the clay modification by the effective breakup of the clay agglomerates and intercalation of the silicate layers. In the mechanical tests of the PUF/clay nanocomposites, the flexural and tensile strengths of the PUF/clay nanocomposites showed the maximum value at 3.0 wt % clay content based on PMDI. These results suggest that the increases in the flexural and tensile strengths were perhaps due to the uniform dispersion of the clay by the application of ultrasound. At the same modified clay content, the fire resistance properties were increased for the PUF/clay nanocomposites with the application of ultrasound compared to the PUF/clay nanocomposites without the application of ultrasound. The cell size and thermal conductivity were decreased for the PUF/clay nanocomposites with the application of ultrasound compared to the PUF/clay nanocomposite without the application of ultrasound. Because of these results, we suggest that the smaller cell size and lower thermal conductivity of the PUF/clay nanocomposites were mainly due to the enhanced dispersion of the clay by the application of ultrasound to the mixture of PMDI and clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3764–3773, 2006
Cure kinetics of aqueous phenol‐formaldehyde resins used for oriented strandboard manufacturing: Effect of wood flour
Authors: Lei Yong , Wu Qinglin
Published: August 2006

The effect of wood flour on the cure kinetics of commercial phenol‐formaldehyde resins used as oriented strandboard face and core adhesives was studied using differential scanning calorimetry. The wood flour did not change the cure mechanism of the face resin, but lowered its cure temperature and activation energy and increased its cure reaction order. For the core resin (CR), the wood flour lowered the onset cure temperature, and caused separation of the addition and condensation reactions involved in curing of CR. Compared with neat CR, the addition reaction of CR/wood mixture also followed an nth‐order reaction mechanism but with a lower reaction order, while the condensation was changed from an autocatalytic reaction to an nth‐order one. The addition reaction happened at temperatures lower than 90°C, and the condensation reaction was dominant at temperatures higher than 110°C. The proposed models fitted the experimental data well. Relationships among cure reaction conversion (cure degree), cure temperature, and cure time were predicted. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3774–3781, 2006
Humidity sensitivity of polypyrrole and polypyrrole/SBA‐15 host–guest composite materials
Authors: Geng Wangchang , Li Xiaotian , Li Nan , Zhang Tong , Wang Wei , Qiu Shilun
Published: August 2006

Polypyrrole (PPY) and PPY/SBA‐15 host–guest composite materials have been prepared using chemical synthesis route and characterized by XRD, IR, N2 adsorption–desorption isotherms, and SEM. The humidity sensitive properties (HSP) of this kind of materials have been studied by analyzing the variation curve of impedance as a function of relative humidity. It was found that the PPY/SBA‐15 host–guest composites materials exhibit better HSP than that of the corresponding pure PPY. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3301–3305, 2006
Environmental effects on poly‐p‐phenylenebenzobisoxazole fibers. II. Attempts at stabilization
Authors: Walsh Peter J. , Hu Xianbo , Cunniff Philip , Lesser Alan J.
Published: August 2006

Approaches to alleviate the environmental degradation of as‐spun poly‐p‐phenylenebenzobisoxazole (PBO AS) fibers by moisture, acidic conditions, and UV–visible radiation were implemented and tested for efficacy. The general approaches tested include: extraction and neutralization of residual phosphoric acid using supercritical carbon dioxide; the use of UV–visible light blocking coatings of exfoliated graphite, carbon black, and glassy titanium dioxide; and improvement of initial fiber properties by the application of forces tending to compact the fiber microstructure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3819–3829, 2006
Interfacial, dynamic mechanical, and thermal fiber reinforced behavior of MAPE treated sisal fiber reinforced HDPE composites
Authors: Mohanty Smita , Nayak Sanjay K.
Published: August 2006

The present article summarizes an experimental study on the mechanical and dynamic mechanical behavior of sisal fiber reinforced HDPE composites. Variations in mechanical strength, storage modulus (E′), loss modulus (E″), and damping parameter (tan δ) with the addition of fibers and coupling agents were investigated. It was observed that the tensile, flexural, and impact strengths increased with the increase in fiber loading up to 30%, above which there was a significant deterioration in the mechanical strength. Further, the composites treated with MAPE showed improved properties in comparison with the untreated composites. Dynamic mechanical analysis data also showed an increase in the storage modulus of the treated composites The tan δ spectra presented a strong influence of fiber content and coupling agent on the α and γ relaxation process of HDPE. The thermal behavior of the composites was evaluated from TGA/DTG thermograms. The fiber–matrix morphology in the treated composites was confirmed by SEM analysis of the tensile fractured specimens. FTIR spectra of the treated and untreated composites were also studied, to ascertain the existence of type of interfacial bonds. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3306–3315, 2006
Fully aliphatic polyimides from adamantane‐based diamines for enhanced thermal stability, solubility, transparency, and low dielectric constant
Authors: Mathews Anu Stella , Kim Il , Ha Chang‐Sik
Published: August 2006

We have synthesized a series of fully aliphatic polyimides (APIs) from bicyclo[2,2,2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride (BOCA) and various aliphatic diamines, including linear aliphatic, flexible alicyclic, and rigid adamantyl diamines. We performed the polymerization reactions using one‐step syntheses in m‐cresol at elevated temperatures without the isolation of poly(amic) acid. The chemical composition and structure of the polymers were characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectrometry. The characterization data are reported from analyses using gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), and wide‐angle X‐ray diffraction (WXAD) measurements. The polyimides are also subjected to solubility, solution viscosity, tensile strength, transparency, and dielectric constant measurements. The resultant polyimides possess well‐controlled molecular weight, reasonable intrinsic viscosity, good transparency, enhanced solubility, low dielectric constants, and high glass transition temperature, together with marginal thermal and mechanical stability. These properties were enhanced in copolyimides containing equimolar amounts of rigid and flexible moieties. These rigid‐rod APIs derived from the alicyclic dianhydride and aliphatic diamines are promising candidates as advanced materials for future applications in micro‐ and photoelectronic devices. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3316–3326, 2006
Effects of polyaniline content in chlorrub‐based coatings on corrosion protection of steel
Authors: Sathiyanarayanan S. , Muthukrishnan S. , Venkatachari G.
Published: August 2006

Corrosion protection of steel coated with chlorrub resin containing polyaniline has been studied in 3% NaCl by electrochemical impedance spectroscopy (EIS). Polyaniline was prepared by oxidative polymerization of aniline using ammonium persulphate in HCl medium. Using the synthesized polyaniline, paints were prepared using chlorrub resin with 1, 3, and 5% polyaniline. The variation of resistance and capacitance of the coating with time has been found out be EIS. The study has shown that the polyaniline content of 1% is able to offer sufficient protection of steel in neutral media and usage of higher percentage of polyaniline does not have beneficial effect. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3994–3999, 2006
Synthesis and characterization of butyl acrylate graft sodium salt of partially carboxymethylated starch
Authors: Patel V. M. , Parikh D. N. , Patel J. V. , Pandya P. D.
Published: August 2006

Graft copolymers were synthesized by graft copolymerization of butyl acrylate (BA) onto sodium salt of partially carboxymethylated starch (Na‐PCMS). Ceric ammonium nitrate (CAN), a redox initiator, was used for initiation of graft copolymerization reaction. All the experiments were run with Na‐PCMS having degree of substitution, DS = 0.35. The grafting reaction was characterized by parameters such as % total conversion (%Ct), % grafting (%G), % grafting efficiency (%GE), and % add‐on. Graft copolymers were characterized by infrared spectral analysis and scanning electron microscopy. Variables affecting graft copolymerization reaction such as nitric acid concentration, reaction time, reaction temperature, and ceric ion concentration were investigated. The results revealed that 0.3M CAN as initiator, 0.3M HNO3, with reaction time 4–4.5 h at 25–30°C were found as suitable parameters for maximum yield of graft copolymerization reaction. © 2006 Wiley Periodicals, Inc. JAppl Polym Sci 102: 3334–3340, 2006
Theoretical and experimental studies of anisotropic shrinkage in injection moldings of various polyesters
Authors: Kwon Keehae , Isayev A. I. , Kim K. H.
Published: August 2006

A novel approach to predict anisotropic shrinkage of slow crystallizing polymers in injection moldings was proposed, using the flow‐induced crystallization, frozen‐in molecular orientation, elastic recovery, and PVT equation of state. In the present study, three different polyesters, polyethylene terephthalate, polybutylene terephthalate, and polyethylene‐2,6‐naphthalate (PEN), are used. The anisotropic thermal expansion and compressibility affected by the frozen‐in orientation function and the elastic recovery that was not frozen during moldings were introduced to obtain the in‐plane anisotropic shrinkages. The frozen‐in orientation function was calculated from the amorphous contribution based on the frozen‐in and intrinsic amorphous birefringence and crystalline contribution based on the crystalline orientation function determined from the elastic recovery and intrinsic crystalline birefringence. To model the elastic recovery and frozen‐in stresses related to birefringence during molding process, a nonlinear viscoelastic constitutive equation was used with the temperature‐dependent viscosity and relaxation time. Occurrence of the flow‐induced crystallization was introduced through the elevation of melting temperature affected by entropy production during flow of the viscoelastic melt. Kinetics of the crystallization was modeled using Nakamura and Hoffman‐Lauritzen equations with the rate constant affected by the elevated melting temperature. Numerous injection molding runs were carried out by varying the packing time, packing pressure, flow rate, melt and mold temperature, and anisotropic shrinkage of moldings were measured. The experimental results were compared with the simulated data and found in a fair agreement. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3526–3544, 2006
DNA delivery using low molecular water‐soluble chitosan nanocomplex as a biomedical device
Authors: Choi Changyong , Kim Dong‐Gon , Jang Min‐Ja , Kim Tae‐Hyeong , Jang Mi‐Kyeong , Nah Jae‐Woon
Published: August 2006

We investigate the potential of low molecular water‐soluble chitosan (LMWSC), LMWSC–methoxy polyethylene glycol (MPEG) [LCP], and LMWSC–MPEG–cholesterol (LCP–Ch) as a gene carrier. LMWSC with free‐amine group was formed at the low weight ratio, above a 1:2 weight ratio of plasmid DNA:LMWSC. LCP and LCP–Ch achieved complex formation of above 1:8 and 1:24 by reacting with MPEG and cholesterol (Ch) on the amine‐group, respectively. Particle sizes at the pH 6.5 and 7.0 were about 100–120 nm and 120–160 nm, respectively. The surface charge of the complex also depended on the pH. At pH 6.5, the surface charge of the complex was higher than that at pH 7.0. The zeta potential of the LCP modified with MPEG or of the LCP‐Ch modified with cholesterol has lower positive value than that of LMWSC because of the decrease of the positive charge. The morphologies of the complexes by transmission electron microscope were of spherelike shape with the average diameters of about 100–150 nm. Among the three gene carriers, LCP–Ch/plasmid DNA showed the highest gene expression owing to the hydrophobic interaction between cell surface and cholesterol. No cytotoxicity was observed in the gene carriers investigated in this study at various concentrations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3545–3551, 2006
Synthesis and characterization of thermo‐ and pH‐sensitive block copolymers bearing a biotin group at the poly(ethylene oxide) chain end
Authors: Tong Dajun , Yao Jia , Li Haoran , Han Shijun
Published: August 2006

A poly(ethylene oxide)‐block‐poly(dimethylamino ethyl methacrylate) block copolymer (PEO‐b‐PDMAEMA) bearing an amino moiety at the PEO chain end was synthesized by a one‐pot sequential oxyanionic polymerization of ethylene oxide (EO) and dimethylamino ethyl methacrylate (DMAEMA), followed by a coupling reaction between its PEO amino and a biotin derivative. The polymers were charac terized with 1H NMR spectroscopy and gel permeation chromatography. Activated biotin, biotin‐NHS (N‐hydroxysuccinimide), was used to synthesize biotin‐PEO‐PDMAEMA. In aqueous media, the solubility of the copolymer was temperature‐ and pH‐sensitive. The particle size of the micelle formed from functionalized block copolymers was determined by dynamic light scattering. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3552–3558, 2006
Preparation and properties of novel water‐soluble surfactants. I. Synthesis and surface activity of polycarboxylated multihydrophilic surfactants
Authors: Lai Chiu‐Chun , Chen Keng‐Ming
Published: August 2006

A series of novel surfactants containing multianionic and nonionic hydrophilic moieties were prepared by reacting fumaric acid with polyoxyethylenated stearyl ether in the presence of a peroxy‐type free radical initiator to form a carboxylic‐acid‐group‐containing addition product. The structure of these surfactants was confirmed by infrared, nuclear magnetic resonance, and elemental analysis. These surfactants exhibit excellent functional properties of self‐sequestering. This means that besides good surfactant properties, including surface tension, foaming, and wetting, they possess autonomous sequestering ability without any help of additional sequestering agent. When used in cotton bleaching procedures, these surfactants increase the penetration of the fibers of gray fabrics and increase the whiteness of bleached cotton. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3559–3564, 2006