bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of degradation rate of acrylonitrile polymers
Authors: Hou Chen , Qu Rongjun , Qun Wang , Ying Liang
Published: May 2006

Low‐temperature degradations of acrylonitrile homopolymers and acrylonitrile/acrylamide copolymers in air were investigated by IR and thermogravimetry. The degradation rates of acrylonitrile polymers were determined by measurement of normalized absorbance of CN band and effects of the degradation temperature, time, and comonomer on the rate of degradations were discussed. It was found that the polymers start to degrade as the temperature increased to 150°C. In the temperature range of 180–210°C, values of the rate of polymer degradation were maximal and the rate of degradation of acrylonitrile/acrylamide copolymers was higher compared with that of acrylonitrile homopolymers. At 150°C, acrylonitrile homopolymers had an induction period of about 0.5 h. The rate of degradation of acrylonitrile/acrylamide copolymers showed an obvious trend of increase along with acrylamide concentration, and changes of the rate became less prominent as the weight ratio of acrylamide/acrylonitrile went beyond 5/95. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1511–1514, 2006
Improvement of processability of clay/polylactide nanocomposites by a combinational method: In situ polymerization of L‐lactide and melt compounding of polylactide
Authors: Lee Seongnam , Kim Chang‐Hyeon , Park Jung‐Ki
Published: May 2006

A modified clay/polylactide nanocomposite was prepared. The clay was modified by grafting polylactide chains onto the surface of clay. The modified clay was melt‐compounded with a high‐molecular‐weight polylactide matrix. This novel clay/polylactide nanocomposite showed high shear‐thinning behavior when the molecular weight of the grafted poly(L‐lactide) was rather high. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1664–1669, 2006
Thermal analysis and mechanical characterization of maleimide‐functionalized benzoxazine/epoxy copolymers
Authors: Ishida Hatsuo , Ohba Sharon
Published: May 2006

Maleimide‐functionalized benzoxazine is copolymerized with epoxy to improve toughness and processibility without compromising the thermal properties. The incorporation of maleimide functionality into the benzoxazine monomer results in a high performance polymer. All three possible polymerization reactions are confirmed using Fourier transform infrared (FT‐IR) spectroscopy. While maleimide‐functionalized benzoxazine has a glass transition temperature, Tg, of 252°C, a further 25°C increase of Tg is observed when copolymerized with epoxy. The flexural properties are also measured, and the copolymers exhibit a flexural modulus of 4.2–5.0 GPa. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1670–1677, 2006
Tribological properties of micro‐ and nanoparticles‐filled poly(etherimide) composites
Authors: Xian Guijun , Zhang Zhong , Friedrich Klaus
Published: May 2006

It has been found that nano‐ or microsized inorganic particles in general enhance the tribological properties of polymer materials. In the present study, 5 vol % nano‐TiO2 or micro‐CaSiO3 was introduced into a polyetherimide (PEI) matrix composite, which was filled additionally with short carbon fibers (SCF) and graphite flakes. The influence of these inorganic particles on the sliding behavior was investigated with a pin‐on‐disc testing rig at room temperature and 150°C. Experimental results showed that both particles could reduce the wear rate and the frictional coefficient (μ) of the PEI composites under the applied testing conditions. At room temperature, the microparticles‐filled composites exhibited a lower wear rate and μ, while the nano‐TiO2‐filled composites possessed the lowest wear rate and μ at elevated temperature. Enhancement in tribological properties with the addition of the nano‐particles was attributed to the formation of transfer layers on both sliding surfaces together with the reinforcing effect. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1678–1686, 2006
Lipase‐catalyzed synthesis of polyhydric alcohol‐poly(ricinoleic acid) ester star polymers
Authors: Kelly April R. , Hayes Douglas G.
Published: May 2006

Polyesters of poly(ricinoleic acid) and polyol acyl acceptors (trimethylolpropane, pentaerythritol, and dimer diol), examples of lipophilic star polymers, were synthesized via bulk polymerization at 70°C in a 1 to 2‐week period, using immobilized lipases from Candida antarctica B, CAL, and Rhizomucor miehei, RML (Novozyme and Lipozyme, respectively, from Novozymes North America, Franklinton, NC). In the screening of several synthesis procedures, the highest molecular weight and degree of conversion occurred when polyricinoleic acid, synthesized previously from ricinoleic acid using CAL as biocatalyst, was mixed with polyol and either CAL or RML. Such a procedure yielded pentaerythritol–poly(ricinoleic acid) tetraester with an average molecular weight of 4850 ± 440 Da, according to 1H NMR analysis. Seventy‐eight percent of the polyol acyl acceptor's hydroxyl groups were esterified, with the average degree of polymerization for its poly(ricinoleyl) chains being 5.4 ± 0.5. The product mixture contained 83% polyol ester and only 17 wt % nonesterified linear poly(ricinoleic acid). The rate‐limiting step in the formation of poly(ricinoleic acid), propagation, was first‐order with respect to monomer (ricinoleyl acyl groups); and, chain‐transfer reactions were absent. The products formed possessed high viscosity and viscosity indices (155 for the pentaerythritol tetraester) and melting point temperatures below −7.5°C, suggesting their use as environmentally‐friendly lubricant materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1646–1656, 2006
Fabrication and thermal properties of microPCMs: Used melamine‐formaldehyde resin as shell material
Authors: Junfeng Su  , Wang Lixin , Ren Li
Published: May 2006

An in‐situ polymerization process prepared a series of melamine formaldehyde (MF) microcapsules containing phase change material (PCM) as core material. The phase change temperature of this PCM was 24°C and its phase transition heat was 225.5 J/g. The microencapsulated phase change materials (MicroPCMs) were bedded in indoor‐wall materials to store and release heat energy, which would economize heat energy and make the in‐door condition comfortable. We investigated the structural formation mechanism by microscope and scanning electron microscopy (SEM). The superficial morphology measurements indicated the optimal shell material dropping rate 0.5 mL min−1, double‐shell, and temperature elevating speed 2°C/10 min. The results obtained in the present investigation were reasonably understood on the basis of getting determinate rigidity and compacted shell. Also, the observed results were used to control the mass of shell material to get desired thickness of shell. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2006
The effects of metallic derivatives released from montmorillonite on the thermal stability of poly(ethylene terephthalate)/montmorillonite nanocomposites
Authors: Guan Guohu , Li Chuncheng , Zhang Dong , Jin Ye
Published: May 2006

By in situ polycondensation, poly(ethylene terephthalate) (PET)/montmorillonite (MMT) nanocomposites was prepared, which were characterized via X‐ray diffraction and transmission electron microscope. The processing stability of these nanocomposites was investigated by the change of number–average molecular weight and carboxyl terminal group content during injection molding, and the thermal stability of the nanocomposites was investigated via thermogravimetric analysis. It was found that some metallic derivatives released from MMT during polycondensation had a great influence on the processing and thermal stabilities of the nanocomposites. The quantity of these metallic derivatives was determined by inductively coupled plasma. The stabilization effect of phosphorous compounds generated from MMT modified with phosphonium was observed. Processing stability and thermal stability of these nanocomposites exhibited similar trend because of almost the same causes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1692–1699, 2006
Morphology, thermal, and mechanical properties of polyamide 66/clay nanocomposites with epoxy‐modified organoclay
Authors: Gyoo Park Min , Venkataramani Sriram , Kim Sung Chul
Published: May 2006

A new kind of organophilic clay, cotreated by methyl tallow bis‐2‐hydroxyethyl quaternary ammonium and epoxy resin into sodium montmorillonite (to form a strong interaction with polyamide 66 matrix), was prepared and used in preparing PA66/clay nanocomposites (PA66CN) via melt‐compounding method. Three different types of organic clays, CL30B–E00, CL30B–E12, and CL30B–E23, were used to study the effect of epoxy resin in PA66CN. The morphological, mechanical, and thermal properties have been studied using X‐ray diffraction, transmission electron microscopy (TEM), mechanical, and thermal analysis, respectively. TEM analysis of the nanocomposites shows that most of the silicate layers were exfoliated to individual layers and to some thin stacks containing a few layers. PA66CX–E00 and PA66CX–E12 had nearly exfoliated structures in agreement with the SAXS results, while PA66CX–E23 shows a coexistence of intercalated and exfoliated structures. The storage modulus of PA66 nanocomposites was higher than that of the neat PA66 in the whole range of tested temperature. On the other hand, the magnitude of the loss tangent peak in α‐ or β‐transition region decreased gradually with the increase in the clay loading. Multiple melting behavior in PA66 was also observed. Thermal stability more or less decreased with an increasing inorganic content. Young's modulus and tensile strength were enhanced by introducing organoclay. Among the three types of nanocomposites prepared, PA66CX–E12 showed the highest improvement in properties, while PA66CX–E23 showed properties inferior to that of PA66CX–E00 without epoxy resin. In conclusion, an optimum amount of epoxy resin is required to form the strong interaction with the amide group of PA66. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1711–1722, 2006
Preparation of polyvinylamine/polysulfone composite hollow‐fiber membranes and their CO2/CH4 separation performance
Authors: Dong Chuanming , Wang Zhi , Yi Chunhai , Wang Shichang
Published: May 2006

Fixed‐carrier composite hollow‐fiber membranes were prepared with polyvinylamine (PVAm) as the selective layer and a polysulfone ultrafiltration membrane as the substrate. The effects of the PVAm concentration in the coating solution, the number of coatings, and the crosslinking of glutaraldehyde and sulfuric acid on the CO2 permeation rate and CO2/CH4 selectivity of the composite membranes were investigated. As the PVAm concentration and the number of coatings increased, the CO2/CH4 selectivity increased, but the CO2 permeation rate decreased. The membranes crosslinked by glutaraldehyde or sulfuric acid possessed higher CO2/CH4 selectivities but lower CO2 permeation rates. For the pure feed gas, a composite hollow‐fiber membrane coated with a 2 wt % PVAm solution two times and then crosslinked with glutaraldehyde and an acid solution in sequence had a CO2 permeation rate of 3.99 × 10−6 cm3 cm−2 s−1 cmHg−1 and an ideal CO2/CH4 selectivity of 206 at a feed gas pressure of 96 cmHg and 298 K. The effect of time on the performance of the membranes was also investigated. The performance stability of the membranes was good during 6 days of testing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1885–1891, 2006
Effect of heat treatment on the structure and properties of Lyocell fibers
Authors: Zhang Huihui , Shao Huili , Hu Xuechao
Published: May 2006

Lyocell fibers were heat‐treated under different conditions. The tensile strength and initial modulus of the heat‐treated Lyocell fibers increased sharply, whereas the elongation at break decreased. Moreover, applying tension to the fibers during the heat treatment further improved the tensile strength and initial modulus. In addition, the crystallinity of the heat‐treated fibers increased slightly, and there was no obvious change with an increase in the tension; the general orientation of the heat‐treated fibers increased, the crystalline orientation little changed, and the amorphous orientation improved. Also, the improved mechanical properties of the Lyocell fibers via the heat treatment could not be preserved for long. The reason may be that the crystalline structure of the Lyocell fibers was not destroyed and no new crystallites were formed during the heat‐treatment process. Therefore, the heat‐treated Lyocell fibers reverted to their original state with time because there was no crosslinking point to fix the orientation, although the cellulose molecules of the amorphous region of the Lyocell fibers were more oriented by the heat treatment with tension. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1738–1743, 2006
Effect of the epoxy molecular weight on the properties of a cyanate ester/epoxy resin system
Authors: Liang Guozheng , Ren Penggang , Zhang Zengping , Lu Tingli
Published: May 2006

Bisphenol A dicyanate (BADCy) was modified by diglycidyl ether of bisphenol A epoxy resins with different molecular weights [E20 (weight‐average molecular weight = 1000) and E51 (weight‐average molecular weight = 400)] to investigate the effects of the epoxy molecular weight on the properties of the modified systems. The reactions were monitored with differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy, and the results showed that more pentacyclic oxazolidinone rings were formed in BADCy/E51 than in BADCy/E20 with the same epoxy resin weight content. DSC showed that BADCy/E20 had a lower curing temperature than BADCy/E51 because of the higher concentration of hydroxyl groups (OH) in E20. Thermal, moisture absorption, and mechanical testing showed that E51‐modified BADCy performed better because of its lower molecular weight. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1744–1750, 2006
Magnetically active composite cellulose fibers
Authors: Rubacha Marcin
Published: May 2006

A process has been developed for manufacturing magnetically active composite fibers of cellulose using N‐methylmorpholine‐N‐oxide as a direct solvent for this natural polymer. Owing to its elasticity and stability, the process made it possible to add considerable quantities of modifier (up to 50% of fiber weight) to spinning solutions. The incorporation of powdered hard ferrites (barium ferrite) into the polymer solution resulted in fibers with magnetic properties, which exhibited a uniform distribution of the modifier. The results of testing the magnetic properties of the fibers obtained have shown that the coercive force of fibers do not depend on the modifier content, while the residual magnetism increases with the content of the ferromagnetic material. The value of fiber remanence is a fraction of the value of magnetic material remanence, corresponding to its volume content in fibers. This may indicate that the modifier used is chemically stable in the spinning solution medium. The thermal analysis of the fibers (DSC and TGA) has shown no negative effect of the modifiers on the fibers' thermal stability. An undesirable influence of the ferromagnetic compound on the fibers is the deterioration of their mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1529–1534, 2006
N‐phenyl‐3‐substituted 5‐pyrazolone derivatives as organic stabilizers for rigid poly(vinyl chloride) against photodegradation
Authors: Sabaa Magdy W. , Oraby Emad H. , Naby Abir S. Abdel , Mohamed Riham R.
Published: May 2006

N‐Phenyl‐3‐substituted 5‐pyrazolone derivatives were investigated as organic photostabilizers for rigid poly(vinyl chloride) (PVC). Their stabilizing efficiency was evaluated by the determination of the weight loss of the polymer after irradiation for different periods and by the determination of the amount of gel formation as well as the intrinsic viscosity of the soluble fraction of the degraded polymer. Moreover, the efficiency was evaluated from the extent of the discoloration of the degraded polymer. This was attributed not only to the radical trapping potency of the pyrazolone derivatives, which intervened with the radical degradation species in the degradation process of PVC, but also to the blocking of the newly formed radical sites on the polymeric chains. Their stabilizing efficiencies were compared with those of phenyl salicylate and 2‐hydroxy‐4‐(octyloxy)phenyl benzophenone, industrially known UV absorbers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1543–1555, 2006
Interaction of functional groups of gelatin and montmorillonite in nanocomposite
Authors: Xu Shu Wei , Zheng Jun Ping , Tong Lei , Yao Kang De
Published: May 2006

As an amphoteric polyelectrolyte, gelatin could intercalate into the galleries of montmorillonite (MMT). In this paper, sodium laurate/MMT composites and sodium laurate/dehydroxylated MMT composites were introduced as low molecular simulation to investigate the interaction functional groups of gelatin and MMT. The composites were characterized by X‐ray diffraction (XRD), Fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA) and 13C nuclear magnetic resonance (13C NMR). Furthermore, the effect of interaction between gelatin and MMT on the mechanical properties of the composites was investigated. The results indicated that COO−, not COOH, in gelatin chains could interact strongly with the MMT sheets. The reactive sites on MMT were hydroxyl groups, which could interact with COO− in gelatin chains by forming hydrogen bonds. The gelatin/MMT composites prepared in alkalic media have better mechanical properties due to stronger interaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1556–1561, 2006
The tensile properties of strain‐crystallising vulcanisates. I. A new theory to explain strengthening
Authors: Van der Horst M. , McGill W. J. , Woolard C. D.
Published: May 2006

The tensile properties of conventional and peroxide vulcanisates were studied over a range of crosslink densities at room temperature and at 90°C. At 90°C the tensile strength and elongation at break of vulcanisates of lower crosslink density are superior to those at room temperature, while for vulcanisates of higher crosslink density the reverse applies. When strain‐induced crystallites form, they act as crosslinks shortening chains within the network. Shortened chains have lower entropies and a larger force is required for their continued extension, i.e., for a further reduction in their entropy. It is proposed that because these stiffer chains resist deformation, other less stiff chains are preferentially extended. This alters the network deformation pattern, forcing more chains to become load bearing and delaying the development of taut chains or chain sequences. Thus the formation of strain‐induced crystals leads to the slope of the stress–strain curve rising rapidly. At elevated temperatures the rate of nucleation of strain‐induced crystallites is slower but data on stress–strain curves obtained with different temperature programs show that, while strain‐induced crystallization is essential for the development of high tensile strength, delaying their formation to higher elongations is advantageous for high tensile properties. In vulcanisates of higher crosslink density the rate of crystallization at high temperatures becomes too slow. Rupture occurs before strain‐induced crystallites can form and protect the network by altering the network deformation pattern. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1562–1569, 2006
Tensile properties of thermoplastic starch‐PVB blends
Authors: Sita C. , Burns M. , Häβler R. , Focke W. W.
Published: May 2006

Blends of thermoplastic starch and recycled polyvinylbutyral from automotive windscreens were investigated. Mechanically compatible blends are formed at low to intermediate starch content. However, scanning electron microscopy and dynamic‐mechanical analysis revealed a phase‐separated nature for all blend compositions investigated. Tensile properties are negatively affected by aging in a high humidity environment and they deteriorate rapidly when the samples are soaked in water. Synergistic property enhancement was observed for a compound containing 22% thermoplastic starch. It features a higher tensile strength, shows better water resistance, and is significantly less affected by aging. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1751–1755, 2006
Network parameters and volume phase transition behavior of poly(N‐isopropylacrylamide) hydrogels
Authors: Çaykara Tuncer , Kiper Simin , Demirel Gökhan
Published: May 2006

Thermosensitive hydrogels were prepared by free radical polymerization in aqueous solution from N‐isopropylacrylamide (NIPA) monomer and N,N‐methylenebis(acrylamide) (MBAAm) crosslinker. The swelling equilibrium of the hydrogels in deionized water was investigated as a function of temperature and MBAAm content. The results indicated that the swelling behavior and temperature sensitivity of the hydrogels were affected by the amount of MBAAm content. The average molecular mass between crosslinks and polymer–solvent interaction parameter (χ) of the hydrogels were determined from equilibrium swelling values. The swelling variations were explained according to swelling theory based on the hydrogel chemical structure. The swelling equilibrium of the hydrogels was also investigated as a function of temperature in aqueous solutions of the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB). In deionized water, the hydrogels showed a discontinuous volume phase transition at 32°C. In SDS and DTAB solutions, the equilibrium swelling ratio and the volume phase transition temperature (lower critical solution temperature) of the hydrogels increased, which is ascribed to the conversion of nonionic PNIPA hydrogel into polyelectrolyte hydrogels because of binding of surfactant molecules through the hydrophobic interaction. Additionally, the amount of free SDS and DTAB ions was measured at different temperatures by a conductometric method; it was found that the electric conductivity of the PNIPA–surfactant systems depended strongly on both the type and concentration of surfactant solutions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1756–1762, 2006
Simulation of the polymeric fluid flow in the feed distributor of melt blowing process
Authors: Wang Xinhou , Chen Ting , Huang Xiubao
Published: May 2006

The polymeric fluid flow in the feed distributor of melt blowing process is simulated using three‐dimensional finite element method. The numerical results are experimentally verified quantitatively and qualitatively using laser Doppler velocimetry and particle image velocimetry respectively. The effects of the distributor's geometric parameters on the uniformity of the transverse flow distribution are investigated. As the manifold angle increases, the flow distribution curve appears to transform gradually from a “hill” shape to a “bone” shape. The uniformity of flow distribution at distributor outlet, especially the fluctuation at the central part, will be improved by increasing the land height. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1570–1574, 2006
Carbon black filled powdered natural rubber: Preparation, particle size distribution, mechanical properties, and structures
Authors: Zhang Anqiang , Wang Lianshi , Lin Yaling , Mi Xiongfei
Published: May 2006

Carbon black (HAF) filled powdered natural rubber (P(NR/HAF)) was prepared and the particle size distribution, mechanical properties, and micromorphology of P(NR/HAF) were studied. A carbon black–rubber latex coagulation method was developed for preparing carbon black filled free‐flowing, noncontact staining NR powders with particle diameter less than 0.9 mm. A powdering mechanism model was put forward to describe the powdering process, which shows that the key technical points consist in the surfactant with good emulsification properties and the polymer coating resin with good film forming properties. SEM analysis shows that carbon black and rubber matrix have formed a macroscopic homogenization in the P(NR/HAF) particles without contact staining, and carbon black particles are well dispersed in rubber matrix with diameter of about 50–150 nm. P(NR/HAF) vulcanizate showed better mechanical properties than bale natural rubber/carbon black blends (NR/HAF) and simple NR latex/carbon black blends (NRL/HAF), which depends primarily upon the absence of free carbon black, the fine dispersion of filler on the rubber matrix, and the better interaction between carbon black and rubber matrix due to the proper preparation condition of noncontact staining carbon black filled powdered NR. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1763–1774, 2006
Effects of formaldehyde to urea mole ratio on thermal curing behavior of urea–formaldehyde resin and properties of particleboard
Authors: Park Byung‐Dae , Chang Kang Eun , Yong Park Jong
Published: May 2006

As a part of abating the formaldehyde emission (FE) of urea–formaldehyde (UF) resin, this study was conducted to investigate the effects of formaldehyde to urea (F/U) mole ratio on thermal curing behavior of UF resins and properties of PB bonded with them. UF resins synthesized at different F/U mole ratios (i.e., 1.6, 1.4, 1.2, and 1.0) were used for the manufacture of PB. Thermal curing behavior of these UF resins was characterized using differential scanning calorimetry (DSC). As the F/U mole ratio decreases, the gel time, onset and peak temperatures, and heat of reaction (ΔH) increased, while the activation energy (Ea) and rate constant (k) were decreased. The amount of free formaldehyde of UF resin and FE of PB prepared decreased in parallel with decreasing the F/U mole ratio. The internal bond strength, thickness swelling, and water absorption of PB was slightly deteriorated with decreasing the F/U mole ratio of UF resins used. These results indicated that as the F/U mole ratio decreased, the FE of PB was greatly reduced at the expense of the reactivity of UF resin and slight deterioration of performance of PB prepared. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1787–1792, 2006
FT‐Raman studies of a range of polyimides subjected to high‐energy radiations at room and elevated temperatures
Authors: Devasahayam Sheila , Hill David J. T. , Connell John W.
Published: May 2006

A range of polyimides have been subjected to electron beam radiolysis at different temperatures. These polyimides were chemically designed to suit space applications, being either transparent or having groups which provide oxidation resistance. The structural changes that occur in the polyimides, when subjected to electron beam irradiation doses up to 18.5 MGy and up to temperatures close to their glass transition temperatures, were studied using FT‐Raman spectroscopy. The range of polyimides studied included a series of perfluoropolyimides, a silicon‐modified polyimide, and Ultem. The changes in the Raman peak intensities of the different groups indicated scission reactions involving the imide rings and ether linkages. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1575–1582, 2006
Effect of a macromolecular coupling agent on the properties of aluminum hydroxide/PP composites
Authors: Plentz Rafael S. , Miotto Maximiliano , Schneider Elisangela E. , Forte Mş Madalena C. , Mauler Raquel S. , Nachtigall Sonia M. B.
Published: May 2006

Polypropylene (PP)/aluminum hydroxide (ATH) composites were prepared in a melt mixer with addition of polypropylene functionalized with vinyltriethoxysilane (VTES) as a coupling agent. The effects of ATH and PP‐VTES on the melt flow indices (MFI), tensile properties, decomposition temperatures, and flame retardancy of composites were analyzed. It was verified that increased ATH concentration reduced MFI and tensile properties, but increased the decomposition temperature under oxidative atmosphere and improved the flammability properties. Addition of PP modified with VTES slightly improved tensile strength and maximum elongation and granted the best results for the flammability tests of the materials showing that it can be an effective coupling agent for PP/ATH composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1799–1805, 2006
Preparation and characterization of ciprofloxacin‐loaded alginate/chitosan sponge as a wound dressing material
Authors: Öztürk Eylem , Ağalar Canan , Keçeci Kaan , Denkbas̨ Emir B.
Published: May 2006

The aim of this study is preparation and characterization of alginate/chitosan sponges including a model antibiotic (i.e., ciprofloxacin) to use in wound and/or burn treatment. Sponges were prepared firstly by the gelation of sodium alginate followed by lyophilization, crosslinking with calcium chloride, and finally coating with chitosan. Sponges were characterized with respect to morphology, water uptake, in vitro drug release behavior, and antimicrobial activity. Investigated and evaluated parameters in all of these studies were selected as the concentration of calcium chloride, alginate viscosity, drug content, and molecular weight of chitosan. Drug release and water uptake were found to be greatly influenced by these parameters. Water uptake and drug release rate were decreased by increasing the crosslinking density, chitosan molecular weight, and alginate viscosity. In the antimicrobial tests, it was obtained that the antimicrobial activity is directly proportional with the release rates and water uptake. Morphological studies showed a highly porous structure with interconnected pores. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1602–1609, 2006
Phase behavior and properties of in situ‐reinforcing elastomer composites based on thermoplastic elastomers and thermotropic liquid crystalline copolyester
Authors: Saikrasun Sunan , Amornsakchai Taweechai
Published: May 2006

In situ reinforcing composites based on two elastomer matrices very different in melt viscosity, styrene–(ethylene butylene)–styrene triblock copolymer (Kraton G1650) and styrene–(ethylene propylene) diblock copolymer (Kraton G1701), and a thermotropic liquid crystalline polymer (TLCP), Rodrun LC3000, were prepared using a twin‐screw extruder. The rheological behavior, morphology, mechanical and thermal properties of the blends containing various LC3000 contents were investigated. G1650 was found to have much higher shear viscosity than G1701. All neat components and their blends exhibited shear thinning behavior. Melt viscosity of the blends gradually decreased with increasing LC3000 contents. Despite a large difference in melt viscosity of the two matrices, the results showed that the fibrillar morphology was obtained for both as‐extruded strands of LC3000/G1650 and LC3000/G1701 with up to 30 wt % LC3000. At 40 wt % LC3000 or more, the lamellar structure was observed for both types of blends because of the coalescence of liquid TLCP threads that occurred during extrusion. The addition of LC3000 into both elastomer matrices enhanced the tensile modulus considerably whereas the extensibility remarkably decreased. The results obtained from thermogravimetric analysis suggested that an addition of LC3000 into both elastomer matrices improved the thermal resistance significantly in air, but not in nitrogen. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1610–1619, 2006
Separation of phenol from aqueous solution by membrane pervaporation using modified polyurethaneurea membranes
Authors: Sinha Barun , Ghosh Ujjal K. , Pradhan Narayan C. , Adhikari Basudam
Published: May 2006

Hydroxy‐terminated polybutadiene‐based porous and nonporous polyurethaneurea membranes were prepared and used to study the phenol separation efficiency from dilute aqueous solution. The porosity was developed by incorporation of lithium chloride in polymer matrix with subsequent leaching of the same in hot water. The porous membrane showed higher phenol flux over that of nonporous membrane. Permeate containing about 97 wt % phenol was obtained from feed containing 7 wt % phenol, when pervaporation was carried out with porous polyurethaneurea membrane at 75°C. The activation energies for diffusion, permeation, and pervaporation were calculated from Arrhenius plots. From the activation energy values, it was observed that the pervaporation process became easier with increased phenol concentration in the feed and porosity of the membrane used. The membrane boundary resistance was observed to decrease with increase in temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1857–1865, 2006
The effect of crosslinking on the mechanical properties of polylactic acid/polycaprolactone blends
Authors: Semba Takeshi , Kitagawa Kazuo , Ishiaku Umaru Semo , Hamada Hiroyuki
Published: May 2006

The improvement of the brittle behavior of Polylactic acid (PLA) resin was studied by blending it with Polycaprolactone (PCL) resin. These materials were fabricated into the compressed films and injection moldings. The values of tensile modulus and strength were appropriate, judging from the rule of mixtures. However, the ultimate tensile strain was very small. Dicumyl peroxide (DCP) was added to this blend system to improve its ultimate tensile strain. It was found that the value of ultimate tensile strain peaked at low DCP concentration. The samples at low DCP contents show yield point and ductile behavior under tensile test. The impact strength of the optimum composition was 2.5 times superior to neat PLA, and ductile behavior such as plastic deformation was observed at its fracture surface. It was found that the carbonyl groups of the blend material with DCP were altered by using FTIR spectroscopy. Dynamic mechanical analysis data revealed the dual phase nature of PLA/PCL blend albeit with good interfacial adhesion, and the DCP enhanced the viscous property in PCL phase, which agreed with tensile ductility and impact strength. The mechanical properties of this blend are comparable to those of general purpose HIPS and ABS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1816–1825, 2006
pH electrodes constructed from polyaniline/zeolite and polypyrrole/zeolite conductive blends
Authors: Malkaj P. , Dalas E. , Vitoratos E. , Sakkopoulos S.
Published: May 2006

A new type of solid state electrodes sensitive to pH changes is described, in which the chemical‐sensitive layer consists of Pt microparticles deposited on a conducting polymer (polyaniline, polypyrrole) blend containing 22.7% w/w zeolite. These sensors are stable in aqueous electrolyte solutions of low pH value at temperatures up to 45°C with response time in seconds. At 25°C, sensor sensitivity was −310 ± 40 mV/pH and −1300 ± 100 mV/pH for polyaniline and polypyrrole blends, respectively. Interferences appear to be acceptably small. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1853–1856, 2006
A novel alkoxysilane‐modified high solids hydroxyl acrylic polyurethane: Preparation and surface properties
Authors: Zhu Fang , Zhang Gaoyong , Xu Shuyi , Hong Xinlin , Dong Jinfeng
Published: May 2006

Alkoxysilane‐modified high solids hydroxyl acrylic polyurethane was prepared by solution polymerization. Its structure, surface, and thermal properties were investigated by 1H NMR, device of contact angle, thermo gravimetric analysis (TGA), atomic force microscopy (AFM), and X‐ray photoelectron spectroscopy (XPS). Research showed that alkoxysilane modified high solids hydroxyl acrylic polyurethane has superior properties that can be used for automotive paints. The contents of silicone in the alkoxysilane‐modified high solids hydroxyl acrylic polyurethane were 1.25, 1.5, 2, and 2.5 wt %. In this study, γ‐methacryloxypropyltrimethoxysilane (MPTS) was chosen as the modifier. Results showed that the contact angles of water and surface roughness on the film of MPTS modified high solids hydroxyl acrylic polyurethane increased, and thermal stability of the film at high temperatures improved with the increasing of the silicone content in the resins. MPTS modified high solids hydroxyl acrylic polyurethane with 2.5 wt % silicone content had better water resistance, better acid resistance, higher hardness, and excellent weatherability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1866–1871, 2006
Preparation and properties of crosslinked chitosan thermosensitive hydrogel for injectable drug delivery systems
Authors: Zan Jia , Chen Huanhuan , Jiang Guoqiang , Lin Ying , Ding Fuxin
Published: May 2006

The aim of this study was to prepare and investigate the physical properties of a thermosensitive crosslinked chitosan pregel solution, and evaluate the in vitro release profiles of macromolecules from this sol–gel transition system. Chitosan and poly (vinyl alcohol) were used to form an interpenetrating polymeric network with glutaraldehyde as the crosslinker, and glycerophosphate (GP) was added to transform the pH‐dependent solutions into thermosensitive pH‐dependent solutions. Rheological study showed that the gelation was dependent on the crosslink degree and GP concentration of the solution. The crosslinked gel had excellent mechanic properties and no apparent “pores” and formed an integrated hydrogel texture according to scanning electronic micrograph. Gas chromatography test guaranteed the medication safety with no detection of glutaraldehyde remnants in the hydrogels. In vitro release study showed that the gelation does not significantly affect the macromolecules diffusion but the crosslinking degree does. These results indicated that the hydrogel formed an intensified three‐dimensional hybrid network with interpenetrating molecules, which effectively buffered or delayed the macromolecules diffusion. The hydrogels sustained the drug release over 30 days and could be potentially used as in situ gelling implants. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1892–1898, 2006
Miscibility and hydrolytic degradation of bioreabsorbable blends of poly(p‐dioxanone) and poly(L‐lactic acid) prepared by fusion
Authors: Pezzin A. P. T. , Duek E. A. R.
Published: May 2006

Blends of two semicrystalline polymers, poly(L‐lactic acid) (PLLA) and poly(p‐dioxanone) (PPD), were prepared by melting the polymers in different proportions. The miscibility, thermal behavior, dynamic‐mechanical properties, and morphology of these blends were studied using differential scanning calorimetry (DSC), dynamic‐mechanical analysis (DMA), and scanning electron microscopy (SEM). The melting temperature of PPD, determined by DSC, did not change with increasing PLLA content, suggesting that this system was immiscible. The presence of two glass transition temperatures detected by DMA also indicated the total immiscibility of the two polymers and this phase separation was confirmed by SEM. The stability of blends immersed in tubes containing phosphate buffer (pH = 7.4) in a thermally controlled bath at (37 ± 1)°C was assessed using DSC, thermogravimetric analysis (TGA), and SEM. PLLA degraded more slowly than PPD, whereas the blends had a degradation rate that was intermediate to these two polymers. This finding indicated that it was possible to control the degradation rate of the blend by changing its composition. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1899–1912, 2006
ZnS deposition on oxadiazole–terpyridine copolymer
Authors: Chrissanthopoulos A. , Tzanetos N. P. , Andreopoulou A. K. , Kallitsis J. , Dalas E.
Published: May 2006

The combination of inorganic salts and macromolecules leads to supramolecular structures with new interesting physical and chemical properties. The deposition of ZnS (Wurtzite) on oxadiazole–terpyridine copolymer P‐90/10 synthesized by free radical copolymerization were investigated. The apparent order of the crystallization process was found to be 2 that indicated a surface diffusion‐controlled mechanism. Critical nucleus formation proceeds via complexation of the ZnS molecules to the N atoms as concluded from computational chemistry calculations. The number of ions forming the critical nucleus was found experimentally to be (n*exp = 1.71 ± 0.24) in accordance with the computational chemistry calculations by the PM3 method of the MOPAC program package. The surface energy of the growing ZnS phase was found to be 121 mJ/m2 typical for sparingly soluble salts. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1913–1918, 2006
Enhancing the efficiency of MEH‐PPV and PCBM based polymer solar cells via optimization of device configuration and processing conditions
Authors: Chang En Chung , Chao Ching‐Ian , Lee Rong‐Ho
Published: May 2006

Polymer solar cells were fabricated based on an interpenetrated network of conjugated polymer poly(2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene) (MEH‐PPV) as electron donor and fullerene derivative (6,6)‐phenyl‐C61‐butyric acid methyl ester (PCBM) as electron acceptor. The photovoltaic performances were strongly dependent on the surface treatment of anode, conductivity of hole‐transporting material, the thickness of MEH‐PPV:PCBM composite film, and the cathode configuration. Best photovoltaic performances were obtained for the solar cell constructed with O2 plasma‐treated anode glass, high conductivity hole‐transporting material PEDOT, photoactive film thickness of 180 nm, and calcium/silver cathode. Open circuit voltage of 0.79 V, short circuit current density of 4.79 mA/cm2, fill factor of 44.4%, and 2.07% power conversion efficiency were obtained for the solar cell under 80 mW/cm2 white light from a halogen lamp. The influences of device fabrication conditions and configuration on the photovoltaic performance of MEH‐PPV:PCBM composite film‐based polymer solar cells were discussed in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1919–1924, 2006
Determination of the infinite dilution diffusion and activity coefficients of alkanes in polypropylene by inverse gas chromatography
Authors: Zhao Changwei , Li Jiding , Zeng Chuyi
Published: May 2006

Infinite dilution diffusion and activity coefficients of n‐hexane, n‐heptane, and n‐decane in polypropylene were measured from 373.15 to 393.15 K by inverse gas chromatography. The influences of small molecule solvent and temperature on the infinite dilution diffusion and activity coefficients were investigated. The results showed that the infinite dilution diffusion coefficient decreased but the infinite dilution activity coefficient increased with an increasing number of CH2 group in the aliphatic solvents. The temperature increase resulted in the increase in the infinite dilution diffusion coefficient and the decrease in the infinite dilution activity coefficient. The graphs plotted according to the results of the infinite dilution diffusion coefficient versus temperature were in agreement with the Arrhenius equation. Diffusion constant and activation energy were obtained from the Arrhenius equation. Also, the interdependence on the infinite dilute activity coefficient and temperature accorded with Gibbs‐Helmholtz equation. From the temperature dependence of the limiting activity coefficients partial molar excess enthalpy at infinite dilution HE,∞ was obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1925–1930, 2006
Anionic polymerization of lactams: A comparative study on various methods of measuring the conversion of ε‐caprolactam to polyamide 6
Authors: Zhang Cai‐Liang , Feng Lian‐Fang , Hu Guo‐Hua
Published: May 2006

Anionic ring‐opening polymerization of lactams leads to the formation of poly(lactams) or polyamides. This work aimed at comparing the performance of four methods for measuring the conversion of ε‐caprolactam (CL) to polyamide 6. The latter was either a homopolymer (PA6) or grafts onto polystyrene (PS‐g‐PA6 graft copolymer). Those four methods were mass balance based on solvent extraction (methanol, water, THF, or acetone), mass balance based on vacuum drying at 140°C, thermogravimetric analysis (TGA), and elemental analysis based on nitrogen. The mass balances based on methanol extraction and vacuum drying at 140°C and TGA were all suitable for measuring the conversion of CL, whether the resulting polymer was the PA6 or PS‐g‐PA6. The mass balance based on water extraction was good for the PA6 and not good for the PS‐g‐PA6. The elemental analysis based on nitrogen was not suitable for the PA6 nor for the PS‐g‐PA6. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1972–1981, 2006
Effects of crosslinking time and amount of sulfophthalic acid on properties of the sulfonated poly(vinyl alcohol) membrane
Authors: Chanthad C. , Wootthikanokkhan J.
Published: May 2006

A proton‐exchange membrane for a direct methanol fuel cell was prepared by modifying the chemical structure of poly(vinyl alcohol) (PVA) via a sulfonation. The sulfonation was carried out by using sulfophthalic acid (sPTA) as a sulfonating agent. The sulfonated PVA membranes, with a variety of degrees of substitutions, were obtained by varying the crosslinking time and the amount of sulfonating agents. The chemical structure and thermal stability of the sulfonated PVA were characterized by using FTIR and thermogravimetric analysis techniques, respectively. The ion‐exchange capacity (IEC) and water uptake of the sulfonated membranes was evaluated by titration and gravimetry techniques, respectively. It was found that the IEC of the membrane increased with the amount of sPTA. Water uptakes of the membranes could either decrease or remain unchanged with the crosslinking time, depending on the amount of the sulfonating agent used. Methanol permeability values of the membranes treated with 10% sPTA were relatively low, comparing with that of the Nafion 115 membrane. Proton conductivity values of the sulfonated PVA membranes ranged between 0.024 and 0.035 S/cm and they did not remarkably change with the crosslinking time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1931–1936, 2006
Preparation and characterization of poly(silyl ester)s containing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones
Authors: Han Nianfeng , Liu Zonglin , Jin Liqiang , Yue Yun
Published: May 2006

The two poly(silyl ester)s containing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones have been prepared via polycondensation reaction of di‐tert‐butyl adipate and di‐tert‐butyl fumarate with 2,2‐bis(p‐chloro dimethylsiloxy‐phenyl)propane to give tert‐butyl chloride as the condensate. The polymerizations were performed under nitrogen at 110°C for 24 h without addition of solvents and catalysts to obtain the poly(silyl ester)s with weight average molecular weights typically ranging from 5000 to 10,000 g/mol. Characterization of the poly(silyl ester)s included 1H NMR and 13C NMR spectroscopies, infrared spectroscopy, ultraviolet spectroscopy, differential scanning calorimetry, thermogravimetric analysis (TGA), gel permeation chromatography, and Ubbelohde viscometer. The glass transition temperatures (Tg) of the obtained polymers were above zero because of the introducing 2,2‐bis(p‐dimethylsiloxy‐phenyl)propane units in the polymer backbones. The TGA/DTG results showed that the obtained poly(silyl ester)s were stable up to 180°C and the residual weight percent at 800°C were 18 and 9%, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1937–1942, 2006