bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct synthesis of poly(D,L‐lactic acid) by melt polycondensation and its application in drug delivery
Authors: Zhao Yaoming , Wang Zhaoyang , Wang Jun , Mai Hangzhen , Yan Bing , Yang Fan 
Published: December 2003

AbstractStarting from D,L‐acid and SnCl2 as catalyst, poly(D,L‐lactic acid) (PDLLA) was directly synthesized by melt polycondensation. Under the appropriate conditions such as 0.5 wt % SnCl2, 170–180°C, 70 Pa, and 10 h, the viscosity‐average molecular weight (Mη) of PDLLA was 4100 Da. PDLLA produced by the most practical method was used as the drug‐delivery material for erythromycin and ciprofloxacin. The optimal conditions for the preparation of erythromycin–poly(D,L‐lactic acid)–microsphere (ERY–PDLLA–MS) for lung targeting was investigated, and further confirmed by good reappearance tests. DSC and SEM demonstrated that ERY–PDLLA–MS had good spherical shape. The release in vitro of ERY–PDLLA–MS was effective and the half‐time (T1/2) was 51.0 h. After 175 h, the accumulated release percentage was 80.0%. The test in vivo showed that ERY–PDLLA–MS was more easily distributed in rabbit lung tissue. When PDLLA was applied in an antibacterial ciprofloxacin drug‐delivery microsphere (CIP–PDLLA–MS), CIP–PDLLA–MS was also characterized with DSC and SEM, and the release T1/2 in vitro was 24.9 h. After 53.2 h, the accumulated release percentage reached 84.0%, which indicated that CIP–PDLLA–MS was advantageous to long‐term release. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2143–2150, 2004
Study on nanometer‐size styrene‐butadiene multiblock copolymer synthesized by reactive extrusion
Authors: Shishuang Gao , Ying Zhang , Anna Zheng , Xiao Huining 
Published: December 2003

AbstractIn this study, a novel styrene‐b‐butadiene block copolymer was synthesized by bulk anionic polymerization in a corotating closely intermeshing twin‐screw extruder. The structure of the S/B copolymer was determined by characterization methods including FTIR, NMR, dynamic mechanical analysis (DMA), and TEM. It is shown that the polymerized materials exhibit nanometer‐size styrene and butadiene (S/B) multiblock structure and ultrahigh elongation at break, which differs considerably from that of traditional solution polymerizing methods. In terms of the structure of the polymerized products, the mechanism of living anionic polymerization of S/B in a corotating intermeshing twin‐screw extruder is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2265–2270, 2004
Effects of synthesis conditions on the pervaporation properties of poly[1‐(trimethylsilyl)‐1‐propyne] useful for membrane bioreactors
Authors: Volkov V. V. , Fadeev A. G. , Khotimsky V. S. , Litvinova E. G. , Selinskaya Y. A. , McMillan J. D. , Kelley S. S. 
Published: December 2003

AbstractAn integrated fermentation and membrane‐based recovery (pervaporation) process has certain economical advantages in continuous conversion of biomass into alcohols. This article presents new pervaporation data obtained for poly[1‐(trimethylsilyl)‐1‐propyne] (PTMSP) samples synthesized in various conditions. Three different catalytic systems, TaCl5/n‐BuLi, TaCl5/Al(i‐Bu)3, and NbCl5 were used for synthesis of the polymers. It was found that the catalytic system has a significant influence over the properties of membranes made from PTMSP. Although a combination of a high permeation rate and a high ethanol–water separation factor (not less than 15) was provided by all PTMSP samples, the PTMSP samples synthesized with TaCl5/n‐BuLi showed significant deterioration of membrane properties when acetic acid was present in the feed. In contrast, the PTMSP samples synthesized with TaCl5/Al(i‐Bu)3 or NbCl5 showed stable performance in the presence of acetic acid. When using a multicomponent mixture of organics and water, the copermeation of different organic components results in lower separation factor for both ethanol and butanol. These data are consistent with nanoporous morphology of PTMSP. It was demonstrated that pervaporative removal of ethanol improved the overall performance of the fermentation process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2271–2277, 2004
Synthesis and characterization of new optically active poly(amide‐imide‐urethane) thermoplastic elastomers, derived from 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L‐leucine‐p‐aminobenzoic acid) and PEG‐MDI
Authors: Mallakpour Shadpour , Khoee Sepideh 
Published: December 2003

AbstractA new class of optically active poly(amide‐imide‐urethane) was synthesized via two‐step reactions. In the first step, 4,4′‐methylene‐bis(4‐phenylisocyanate) (MDI) reacts with several poly(ethylene glycols) (PEGs) such as PEG‐400, PEG‐600, PEG‐2000, PEG‐4000, and PEG‐6000 to produce the soft segment parts. On the other hand, 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L‐leucine‐p‐amidobenzoic acid) (2) was prepared from the reaction of 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L‐leucine) diacid chloride with p‐aminobenzoic acid to produce hard segment part. The chain extension of the above soft segment with the amide‐imide 2 is the second step to give a homologue series of poly(amide‐imide‐urethanes). The resulting polymers with moderate inherent viscosity of 0.29–1.38 dL/g are optically active and thermally stable. All of the above polymers were fully characterized by IR spectroscopy, elemental analyses, and specific rotation. Some structural characterization and physical properties of this new optically active poly(amide‐imide‐urethanes) are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2288–2294, 2004
Recycling of pharmaceutical waste gelatin for controlled‐release applications. I. A 2,4‐dicholorphenoxy acetic acid based system
Authors: Kandil Sherif , Kenawy El‐Refaie , El‐Maghraby Azza 
Published: December 2003

AbstractGelatin is a natural macromolecular protein. It contains a wide variety of amino acids in its polymer structure, and it is colorless to yellowish, water‐soluble, and tasteless. It is used as a dispersing agent, sizing medium, and coating for photographic films and in pharmaceutical formulations. In this study, biodegradable mulching, based on waste gelatin from pharmaceutical gelatin scraps (derived from pharmaceutical soft gelatin capsule production), was formulated via the casting of water solutions or suspensions into flexible and consistent films. Gelatin was blended with synthetic materials such as poly(vinyl alcohol) and other natural wastes such as sugar cane bagasse and sawdust. To all formulations, 2,4‐dichlorophenoxy acetic acid (2,4‐D) was added as a herbicide. The morphology and mechanical properties of the samples were investigated with scanning electron microscopy and tensile testing, respectively. The results showed that the produced films had controlled‐release properties. The effects of various additives and crosslinking on the films and the release of the herbicide 2,4‐D from the films were also investigated. The introduction of synthetic and natural additives reduced the release rate of 2,4‐D. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2313–2319, 2004
Effect of the reaction atmosphere on high‐density polyethylene functionalized by ultraviolet irradiation
Authors: Wu Shishan , Xu Xi 
Published: December 2003

AbstractThe structure and hydrophilicity of high‐density polyethylene (HDPE) functionalized by ultraviolet irradiation in air and O2 were studied with Fourier transform infrared, X‐ray photoelectron spectroscopy, differential scanning calorimetry, and contact‐angle measurements with water and liquid paraffin. The results showed that CO, C(O)O, and CO functional groups were introduced onto molecular chains of HDPE during irradiation in air and O2, and their contents increased with the irradiation time. The number of oxygen‐containing groups of HDPE irradiated in O2 was much higher than that in air. A higher functionalization efficiency for HDPE was achieved by irradiation in O2. After the irradiation, the contact angle of HDPE with water became smaller, the contact angle of HDPE with liquid paraffin became larger, and the surface tension increased; this showed that the hydrophilicity of irradiated HDPE was improved. HDPE irradiated in O2 exhibited better hydrophilicity than HDPE irradiated in air. Furthermore, with an increase in the irradiation time, the melting temperature of HDPE decreased, and the heat of fusion and the degree of crystallinity increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 00: 2326–2329, 2004
Preparation and characterization of CdS and CdS/polyacrylonitrile nanocomposites by γ‐irradiation and emulsion polymerization
Authors: Choi Seong‐Ho , Choi Min‐Seok , Lee Kwang‐Pill , Kang Hee‐Dong 
Published: December 2003

AbstractCdS and CdS/polyacrylonitrile (PAN) nanocomposites were prepared by γ‐irradiation and emulsion polymerization. The CdS and CdS/PAN nanocomposites were characterized by powder X‐ray diffraction, infrared spectroscopy, Fourier transform Raman spectroscopy, transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, and thermal analysis (thermogravimetric analysis/dynamic thermal analysis). In photoluminescence spectroscopy analysis, the maximum peak of CdS/PAN nanocomposites prepared by γ‐irradiation and emulsion polymerization was at about 485 nm, whereas the maximum peak of CdS nanocomposites was at about 460 nm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2335–2342, 2004
Synthesis and characterization of a terpolymer of limonene, styrene, and methyl methacrylate via a free‐radical route
Authors: Sharma Saroj , Srivastava A. K. 
Published: December 2003

AbstractThe free‐radical terpolymerization of a monocyclic terpene, namely, limonene (Lim), with styrene (Sty) and methyl methacrylate (MMA) in xylene at 80 ± 0.1°C for 2 h, with benzoyl peroxide (BPO) as an initiator under an inert atmosphere of nitrogen was extensively studied. The kinetic expression was Rpα[BPO]0.5[Sty]1.0[MMA]1.0[Lim]−1.0, where Rp is the rate of polymerization. The overall energy of activation was calculated as 26 kJ/mol. Rp decreased as [Lim] increased. This was due to a penultimate unit effect. The Fourier transform infrared spectra of the terpolymer showed bands at 3025–3082, 1728, and 2851–2984 cm−1 due to CH stretching of phenyl (C6H5) protons of Sty, OCH3 of MMA, and trisubstituted olefinic protons of Lim, respectively. The 1H‐NMR spectra showed peaks at 7.3–8.1, 3.9–4.4, and 5.0–5.5 δ due to the phenyl, methoxy, and trisubstituted olefinic protons of Sty, MMA and Lim, respectively. The values of the reactivity ratios r1 (MMA; 0.33) and r2 (Sty + Lim; 0.06) were calculated with the Kelen–T̈udos method. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2343–2347, 2004
Properties of crosslinked blends of pellethene and multiblock polyurethane containing poly(ethylene oxide) for biomaterials
Authors: Yoo Hye‐Jin , Kim Han‐Do 
Published: December 2003

AbstractA series of multiblock polyurethanes, containing various poly(ethylene oxide) (PEO; number‐average molecular weight = 400–3400) contents (0–80 wt %) and prepared from hexamethylene diisocyanate/PEO/poly(dimethylsiloxane) diol/polybutadiene diol/1,4‐butanediol, were used as modifying additives (30 wt %) to improve the properties of biomedical‐grade Pellethene. Different molecular weights of PEO were used to keep poly(ethylene glycol) at a fixed molar content, if possible, although the PEO content, related to the PEO block length in the multiblock polyurethanes, was varied from 0 to 80 wt %. The hydrophilic PEO component was introduced through the addition of PEO‐containing polyurethanes and dicumyl peroxide as a crosslinking agent in a Pellethene matrix. As the PEO content (PEO block length) increased, the hydrogen‐bonding fraction of the crosslinked Pellethene/multiblock polyurethane blends increased, and this indicated an increase in the phase separation with an increase in the PEO content in the crosslinked Pellethene/multiblock polyurethane blends. According to electron spectroscopy for chemical analysis, the ratio of ether carbon to alkyl carbon in the crosslinked Pellethene/multiblock polyurethane blends increased remarkably with increasing PEO content. The water contact angle of the crosslinked Pellethene/multiblock polyurethane blend film surfaces decreased with increasing PEO content. The water absorption and mechanical properties (tensile modulus, strength, and elongation at break) of the crosslinked Pellethene/multiblock polyurethane blend films increased with increasing PEO content. The platelet adhesion on the crosslinked Pellethene/multiblock polyurethane blend film surfaces decreased significantly with increasing PEO content. These results suggest that crosslinked Pellethene/multiblock polyurethane blends containing the hydrophilic component PEO may have potential for biomaterials that come into direct contact with blood. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2348–2357, 2004
Monomolecular chain termination in the kinetics of dimethacrylate postpolymerization
Authors: Medvedevskikh Y. G. , Kytsya A. R. , Bazylyak L. I. , Bratus A. M. , Turovski A. A. , Zaikov G. E. 
Published: December 2003

AbstractThe kinetics of postpolymerization (after ultraviolet illumination was stopped) for a number of dimethacrylates that differed by nature and molecular mass was experimentally studied over a wide range of temperatures. A series of kinetic curves that differed by the starting conversion of the dark period of time was obtained for every temperature. The proposed kinetic model of the process is based on the following main principles: (1) the process at an interface on the liquid monomer–solid polymer (micrograins) boundary takes a main share of the kinetics of postpolymerization; (2) chain termination at an interface is monomolecular, is controlled by the chain propagation rate, and represents by itself the self‐burial act of active radicals in the conformation trap; and (3) monomolecular chain termination is characterized by a wide spectrum of characteristic times and that is why the function of the relaxation is described by Kohlrausch's stretched exponential law. The obtained kinetic equation was in good agreement with all of the sets of experimental data. This permitted us to estimate the rate constant of chain termination (kt) and to determine the scaling dependence of kt on the molar‐volumetric concentration of the monomer in bulk [M0]. We assumed that the stretched exponential law and scaling dependence kt from [M0] were characterized by common peculiarities, namely, a wide range of characteristic times of relaxation possessed by a property of the fractal set. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2376–2382, 2004
Biodegradation of Bombyx mori silk fibroin fibers and films
Authors: Arai Takayuki , Freddi Giuliano , Innocenti Riccardo , Tsukada Masuhiro 
Published: December 2003

AbstractThe in vitro biodegradation of Bombyx mori silk fibroin was studied by incubating fibers and films with proteolytic enzymes (collagenase type F, α‐chymotrypsin type I‐S, protease type XXI), for times ranging from 1 to 17 days. The changes in sample weight and degree of polymerization of silk fibers exposed to proteolytic attack were negligible. However, tensile properties were significantly affected, as shown by the drop of strength and elongation as a function of the degradation time. Upon incubation with proteolytic enzymes, silk films exhibited a noticeable decrease of sample weight and degree of polymerization, the extent of which depended on the type of enzyme, on the enzyme‐to‐substrate ratio, and on the degradation time. Protease was more aggressive than α‐chymotrypsin or collagenase. Film fragments resistant to enzymatic degradation were enriched in glycine and alanine. FT‐IR measurements showed that the degree of crystallinity of biodegraded films increased. Soluble degradation products of silk films consisted of a range of peptides widely differing in size, deriving from the amorphous sequences of the silk fibroin chains. Biodegraded fibers showed an increase of surface roughness, while films displayed surface cracks and cavities with internal voids separated by fiber‐like elements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2383–2390, 2004
Electrorheological behavior of side‐chain polysiloxane containing 3‐(4‐amidophenyl) sydnone moieties
Authors: Yan Hua , Chan Wing Lai , Szeto Yau Shan 
Published: December 2003

AbstractSide‐chain polysiloxane containing 3‐(4‐amidophenyl) sydnone moieties at terminal and aliphatic spacer has been synthesized and its structure was confirmed by FTIR and 1H‐NMR. Low mass molar weight sydnone exhibited electrorheological effect, which was enhanced by electron‐donor substituted group at phenyl, but weakened by electron‐acceptor substituted group. By introducing sydnone into polysiloxane, the polymer displays the higher electrorheological effect due to the increased interaction between sydnone molecules. The oxide states of sydnone affect the electrorheological effect as well as the color of the product. Moreover, the temperature is higher than the glass transfer temperature of the polymer; the electrorheological fluids show a very large leakage current. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2523–2528, 2004
Influence of organophilic clay and preparation methods on EVA/montmorillonite nanocomposites
Authors: Tang Yong , Hu Yuan , Wang Junzhong , Zong Ruowen , Gui Zhou , Chen Zuyao , Zhuang Yonglong , Fan Weicheng 
Published: December 2003

AbstractEthylene‐vinyl acetate copolymer (EVA)/montmorillonite MMT nanocomposites have been prepared by using different methods: one is from the organophilic montmorillonite (OMT) and the other is from the pristine MMT and reactive compatibilizer hexadecyl trimethyl ammonium bromide (C16). In this study, different kneaders were used (twin‐screw extruder and twin‐roll mill) to prepare nanocomposites. The nanocomposite structures are evidenced by the X‐ray diffraction (XRD) and high‐resolution electronic microscope (HREM). The thermal properties of the nanocomposites were investigated by thermogravimetric analysis (TGA). Moreover, the tensile tests were carried out with a Universal testing machine DCS‐5000. It is shown that different methods and organophilic montmorillonite have influence on EVA/MMT nanocomposites.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2416–2421, 2004
Rheology of poly(propylene)/clay nanocomposites
Authors: Gu Shu‐Ying , Ren Jie , Wang Qin‐Feng 
Published: December 2003

AbstractThe linear and nonlinear shear rheological behaviors of poly(propylene) (PP)/clay (organophilic‐montmorillonite) nanocomposites (PP/org‐MMT) were investigated by an ARES rheometer. The materials were prepared by melt intercalation with maleic anhydride functionalized PP as a compatibilizer. The storage moduli (G′), loss moduli (G″), and dynamic viscosities of polymer/clay nanocomposites (PPCNs) increase monotonically with org‐MMT content. The presence of org‐MMT leads to pseudo‐solid‐like behaviors and slower relaxation behaviors of PPCN melts. For all samples, the dependence of G′ and G″ on ω shows nonterminal behaviors. At lower frequency, the steady shear viscosities of PPCNs increase with org‐MMT content. However, the PPCN melts show a greater shear thinning tendency than pure PP melt because of the preferential orientation of the MMT layers. Therefore, PPCNs have higher moduli but better processibility compared with pure PP.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2427–2434,2004
Crystallization and melting behavior of nano‐CaCO3/polypropylene composites modified by acrylic acid
Authors: Lin Zhidan , Huang Zhenzhen , Zhang Yu , Mai Kancheng , Zeng Hanmin 
Published: December 2003

AbstractNano‐CaCO3/polypropylene (PP) composites modified with polypropylene grafted with acrylic acid (PP‐g‐AA) or acrylic acid with and without dicumyl peroxide (DCP) were prepared by a twin‐screw extruder. The crystallization and melting behavior of PP in the composites were investigated by DSC. The experimental results showed that the crystallization temperature of PP in the composites increased with increasing nano‐CaCO3 content. Addition of PP‐g‐AA further increased the crystallization temperatures of PP in the composites. It is suggested that PP‐g‐AA could improve the nucleation effect of nano‐CaCO3. However, the improvement in the nucleation effect of nano‐CaCO3 would be saturated when the PP‐g‐AA content of 5 phf (parts per hundred based on weight of filler) was used. The increase in the crystallization temperature of PP was observed by adding AA into the composites and the crystallization temperature of the composites increased with increasing AA content. It is suggested that the AA reacted with nano‐CaCO3 and the formation of Ca(AA)2 promoted the nucleation of PP. In the presence of DCP, the increment of the AA content had no significant influence on the crystallization temperature of PP in the composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2443–2453, 2004
Conversion of polyester into heat‐resistant polyamide by reacting with aromatic diamine compound
Authors: Kim Yangsoo , Roh Hang‐Duk , Lee Hyung‐Chan 
Published: December 2003

AbstractThe ester–amide exchange reaction between poly(ethylene terephthalate) and p‐phenylenediamine in n‐dodecylbenzene as a solvent in the absence of catalyst was carried out to obtain heat‐resistant polyamide. The observation of the amide group generated in the reaction product was made by FTIR analysis and the relative extent of reaction was estimated by the amidation ratio from FTIR and the nitrogen content determined from elemental analysis. The effect of chemical structure in the homologous series of aliphatic and aromatic diamines on the reactivity of ester–amide exchange reaction was studied. How reaction variables such as time, temperature, and the amount of diamine used affected the extent of reaction and the heat‐resistant property of polyamide obtained was thoroughly studied. Finally, a search for an efficient catalyst among metal acetates was attempted. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2502–2512, 2004
Durable and regenerable antimicrobial textiles: Improving efficacy and durability of biocidal functions
Authors: Qian Lei , Sun Gang 
Published: December 2003

Abstract2,2,5,5‐Tetramethylimidazolidinone (TMIO)‐modified cotton‐containing fabrics could provide excellent durable antimicrobial properties, but the biocidal speeds were low because of its amine halamine structures. To prepare biocidal fabrics that can inactivate microorganisms rapidly and survive repeated laundering and long duration of storage, 3‐methylol‐2,2,5,5‐tetramethylimidazolidinone and dimethylol‐5,5‐dimethylhydantoin were combined in different ratios in chemical modifications of cellulose fabrics. The mixtures of TMIO and hydantoin rings on the grafted cellulose provided a hybrid of imide, amide, and amine halamine structures in different ratios after chlorination, and led to varied efficacy and durability of biocidal properties on the finished fabrics. The effect of the combined halamine structures on biocidal efficacy and durability of the fabrics were discussed in this article. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2588‐2593, 2004