bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lipase‐catalyzed synthesis of polyhydric alcohol‐poly(ricinoleic acid) ester star polymers
Authors: Kelly April R. , Hayes Douglas G. 
Published: May 2006

AbstractPolyesters 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

AbstractAn 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

AbstractBy 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

AbstractA 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

AbstractFixed‐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

AbstractLyocell 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

AbstractBisphenol 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

AbstractA 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

AbstractN‐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

AbstractAs 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

AbstractThe 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

AbstractBlends 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

AbstractThermosensitive 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

AbstractThe 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

AbstractCarbon 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

AbstractAs 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

AbstractA 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