bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel mutations in the Na+, K+‐ATPase pump gene ATP1A2 associated with familial hemiplegic migraine and benign familial infantile convulsions
Authors: Vanmolkot Kaate R. J. , Kors Esther E. , Hottenga Jouke‐Jan , Terwindt Gisela M. , Haan Joost , Hoefnagels Wil A. J. , Black David F. , Sandkuijl Lodewijk A. , Frants Rune R. , Ferrari Michel D. , Van Den Maagdenberg Arn M. J. M.
Published: September 2003

Familial hemiplegic migraine (FHM) is a rare, severe, autosomal dominant subtype of migraine with aura. Up to 75% of FHM families have a mutation in the P/Q‐type calcium channel Cav2.1 subunit CACNA1A gene on chromosome 19p13. Some CACNA1A mutations also may cause epilepsy. Here, we describe novel missense mutations in the ATP1A2 Na+,K+‐ATPase pump gene on chromosome 1q23 in two families with FHM. The M731T mutation was found in a family with pure FHM. The R689Q mutation was identified in a family in which FHM and benign familial infantile convulsions partially cosegregate. In this family, all available affected family members with FHM, benign familial infantile convulsions, or both, carry the ATP1A2 mutation. Like FHM linked to 19p13, FHM linked to 1q23 also involves dysfunction of ion transportation and epilepsy is part of its phenotypic spectrum.
The role of pathogenic DJ‐1 mutations in Parkinson's disease
Authors: Abou‐Sleiman Patrick M. , Healy Daniel G. , Quinn Niall , Lees Andrew J. , Wood Nicholas W.
Published: September 2003

Mutations in DJ‐1 (PARK7) have been reported in two consanguineous families with young‐onset Parkinson's disease (YOPD). This study aims to confirm the presence of pathogenic DJ‐1 mutations and determine their contribution in young‐onset and more typical later onset Parkinson's disease (PD). The entire open reading frame of the DJ‐1 gene was screened by direct sequencing in 185 unrelated YOPD patients and a separate cohort of 190 pathologically proven cases of PD. Ethnically matched controls were screened for all mutations identified. We report a low frequency of pathogenic DJ‐1 mutations in our cohort of patients. One homozygous missense mutation and one heterozygous mutation were found in two YOPD samples. In addition, several variants were found in the coding sequence of the gene, which are likely to represent polymorphisms. In one case, the polymorphism was population specific. The reported 14Kbp deletion was not found in any of our samples or controls. We confirm the presence of pathogenic DJ‐1 mutations in YOPD and estimate their frequency at approximately 1%. No mutations were found in our cohort of later onset sporadic pathologically confirmed cases, suggesting that DJ‐1 mutations may only rarely contribute to the cause of this more typical sporadic form of the disease.
Clinical features and neuropathology of autosomal dominant spinocerebellar ataxia (SCA17)
Authors: Rolfs Arndt , Koeppen Arnulf H. , Bauer Ingrid , Bauer Peter , Buhlmann Sven , Topka Helge , Schöls Ludger , Riess Olaf
Published: September 2003

Autosomal dominant spinocerebellar ataxias (SCAs) are a group of neurodegenerative disorders clinically characterized by late‐onset ataxia and variable other manifestations. Genetically and clinically, SCA is highly heterogeneous. Recently, CAG repeat expansions in the gene encoding TATA‐binding protein (TBP) have been found in a new form of SCA, which has been designated SCA17. To estimate the frequency of SCA17 among white SCA patients and to define the phenotypic variability, we determined the frequency of SCA17 in a large sample of 1,318 SCA patients. In total, 15 patients in four autosomal dominant SCA families had CAG/CAA repeat expansions in the TBP gene ranging from 45 to 54 repeats. The clinical features of our SCA17 patients differ from other SCA types by manifesting with psychiatric abnormalities and dementia. The neuropathology of SCA17 can be classified as a “pure cerebellar” or “cerebello‐olivary” form of ataxia. However, intranuclear neuronal inclusion bodies with immunoreactivity to anti‐TBP and antipolyglutamine were much more widely distributed throughout the brain gray matter than in other SCAs. Based on clinical and genetic data, we conclude that SCA17 is rare among white SCA patients. SCA17 should be considered in sporadic and familial cases of ataxia with accompanying psychiatric symptoms and dementia.
Monocyte chemoattractant protein–1 increases microglial infiltration and aggressiveness of gliomas
Authors: Platten Michael , Kretz Alexandra , Naumann Ulrike , Aulwurm Steffen , Egashira Kensuke , Isenmann Stefan , Weller Michael
Published: September 2003

Macrophages are thought to represent a first line of defense in anti‐tumor immunity. Despite infiltration by microglial cells, however, malignant gliomas are still highly aggressive tumors. We here identify monocyte chemoattractant protein‐1 (MCP‐1) as a critical chemoattractant for glioma‐infiltrating microglial cells. MCP‐1–transfected rat CNS‐1 gliomas were massively infiltrated by microglial cells. Whereas MCP‐1 did not promote the growth of CNS‐1 cells in vitro, intracerebral CNS‐1–transfected tumors grew more aggressively than control‐transfected tumors. This provides the first functional evidence that MCP‐1 recruits microglial cells to gliomas and promotes their growth in vivo. Microglial cells may support rather than suppress glioma growth.
Caspase activation in the limbic cortex of subjects with early Alzheimer's disease
Authors: Gastard Myriam C. , Troncoso Juan C. , Koliatsos Vassilis E.
Published: September 2003

We investigated the cleavage of caspase‐3, a marker of apoptosis, in the medial temporal lobe of older subjects with minimal cognitive deficits and low CERAD/intermediate Braak scores, that is, clinicopathological descriptors of early Alzheimer's disease (AD). The activation of caspase‐3 was studied with immunoprecipitation–mass spectroscopy and immunocytochemistry, including colocalization with paired helical filaments in the neuropil and perikarya. We found that caspase‐3 is activated in the parahippocampal gyrus in subjects with mild AD and that this event is silenced in more advanced illness. Caspase‐3 immunoreactivity has a tangle‐like appearance that coevolves with paired helical filament pathology within neurons. We propose that activation of apoptosis may occur very early in the medial temporal lobe in AD. Ann Neurol 2003;54:393–398
Disturbance of muscle fiber differentiation in congenital hypomyelinating neuropathy caused by a novel myelin protein zero mutation
Authors: Szigeti Kinga , Saifi Gulam Mustafa , Armstrong Dawna , Belmont John W. , Miller Geoffrey , Lupski James R.
Published: September 2003

We report a case of congenital hypomyelination associated with cranial nerve dysfunction, respiratory failure, and hypertrophic cardiomyopathy confounding the clinical picture. Molecular genetic testing showed a complex de novo myelin protein zero (MPZ) mutation consisting of a 3bp deletion of CTA from nucleotide 550 to 552 and insertion of G at nucleotide 550 that by conceptual translation results in a frameshift mutation. Muscle biopsy findings are presented that allude to the effect of abnormal innervation on early postnatal muscle differentiation.
A double‐blind controlled trial of bilateral fetal nigral transplantation in Parkinson's disease
Authors: Olanow C. Warren , Goetz Christopher G. , Kordower Jeffrey H. , Stoessl A. Jon , Sossi Vesna , Brin Mitchell F. , Shannon Kathleen M. , Nauert G. Michael , Perl Daniel P. , Godbold James , Freeman Thomas B.
Published: September 2003

Thirty‐four patients with advanced Parkinson's disease participated in a prospective 24‐month double‐blind, placebo‐controlled trial of fetal nigral transplantation. Patients were randomized to receive bilateral transplantation with one or four donors per side or a placebo procedure. The primary end point was change between baseline and final visits in motor component of the Unified Parkinson's Disease Rating Scale in the practically defined off state. There was no significant overall treatment effect (p = 0.244). Patients in the placebo and one‐donor groups deteriorated by 9.4 ± 4.25 and 3.5 ± 4.23 points, respectively, whereas those in the four‐donor group improved by 0.72 ± 4.05 points. Pairwise comparisons were not significant, although the four‐donor versus placebo groups yielded a p value of 0.096. Stratification based on disease severity showed a treatment effect in milder patients (p = 0.006). Striatal fluorodopa uptake was significantly increased after transplantation in both groups and robust survival of dopamine neurons was observed at postmortem examination. Fifty‐six percent of transplanted patients developed dyskinesia that persisted after overnight withdrawal of dopaminergic medication (“off”‐medication dyskinesia). Fetal nigral transplantation currently cannot be recommended as a therapy for PD based on these results.Ann Neurol 2003;54:403–414
Acute motor axonal neuropathy rabbit model: Immune attack on nerve root axons
Authors: Susuki Keiichiro , Nishimoto Yukihiro , Yamada Mitsunori , Baba Masayuki , Ueda Shuichi , Hirata Koichi , Yuki Nobuhiro
Published: September 2003

Macrophages in the periaxonal space and surrounding intact myelin sheath are the most prominent pathological feature of acute motor axonal neuropathy (AMAN). We describe this characteristic in nerve roots from paralyzed rabbits immunized with bovine brain ganglioside or GM1. IgG was deposited on nerve root axons. Distal nerve conduction was preserved, and late F wave components were absent during the acute phase. Initial lesions were located mainly on nerve root axons, as in human AMAN. This study thus provides supportive evidence that the rabbits constitute a model of AMAN. Ann Neurol 2003;54:000–000
Synthesis, characterization, and catalytic activity of crosslinked poly(N‐vinyl‐2‐pyrrolidone acrylic acid) copolymer–metal complexes
Authors: Jose Jincy , John Magi , Gigimol M. G. , Mathew Beena
Published: September 2003

This article describes the development of a new crosslinked poly(N‐vinyl‐2‐pyrrolidone acrylic acid) copolymer for potential applications in catalase‐like activity for the decomposition of hydrogen peroxide. The copolymer, crosslinked with hexanediol diacrylate (4 mol %), was prepared by the suspension polymerization of the monomers in water. The metal‐ion complexation of copolymer‐derived sodium salts was investigated for Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) ions. The metal uptake varied in the following order: Cu(II) > Cr(III) > Mn(II) > Co(II) > Fe(III) > Ni(II) > Zn(II). The polymer and metal complexes were characterized by 13C cross‐polarity/magic‐angle spinning NMR, Fourier transform infrared, ultraviolet–visible, electron paramagnetic resonance, thermogravimetry, and scanning electron microscopy analyses. The catalase‐like activities of these insoluble metal complexes were investigated for the decomposition of hydrogen peroxide. Co(II) and Cu(II) complexes were effective for the catalytic decomposition of hydrogen peroxide. The catalytic decomposition was first‐order. The effects of various parameters, such as the time, temperature, pH, amount of the catalyst, concentration of hydrogen peroxide, and recyclability of the catalyst, were examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 895–904, 2003
Study of hyperbranched poly(glycidol) sulfate electrolyte
Authors: Xiaohui Yang , Xiaoying Sun , Jianjun Chen , Yunhang Liu , Xinling Wang
Published: September 2003

Hyperbranched poly(glycidol) alkali sulfate (SHPG‐M) was prepared based on hyperbranched poly(glycidol). Polyurethane–hyperbranched poly(glycidol) (PU–SHPG‐M) sulfate electrolyte is a kind of single ionic or cationic conducting polymer electrolyte. Such a single ionic polymer electrolyte can obviously reduce the polarization and has little decay of direct current (DC) conductivity. SHPG‐M was characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), atomic force microscopy (AFM) and impedance analysis. The optimum conductivity is ∼3 × 10−6 S·cm−1, with 30–40% SHPG‐M in the polymer electrolyte at room temperature. The species of cation greatly effects the ionic conductivity of the polymer electrolyte; that is, σSHPG‐Li > σSHPG‐Na > σSHPG‐K, with same SHPG‐M content in the polymer electrolyte. The ionic conductivity increases with an increase of temperature, and the dependence of ionic conductivity on temperature fits the Arrhenius equation well. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1185–1190, 2003
Semi‐interpenetrating polymer networks based on polyurethane and polyvinylpyrrolidone. II. Dielectric relaxation and thermal behaviour
Authors: Karabanova L. V. , Boiteux G. , Gain O. , Seytre G. , Sergeeva L. M. , Lutsyk E. D. , Bondarenko P. A.
Published: September 2003

Semi‐interpenetrating polymer networks (semi‐IPNs) based on crosslinked polyurethane (PU) and linear polyvinylpyrrolidone (PVP) were synthezised, and their thermal and dynamic mechanical properties and dielectric relaxation behavior were studied to provide insight into their structure, especially according to their composition. The differential scanning calorimetry results showed the glass transitions of the pure components: one glass‐transition temperature (Tg) for PU and two transitions for PVP. Such glass transitions were also present in the semi‐IPNs, whatever their composition. The viscoelastic properties of the semi‐IPNs reflected their thermal behavior; it was shown that the semi‐IPNs presented three distinct dynamic mechanical relaxations related to these three Tg values. Although the temperature position of the PU maximum tan δ of the α‐relaxation was invariable, on the contrary the situation for the two maxima observed for PVP was more complex. Only the maximum of the highest temperature relaxation was shifted to lower temperatures with decreasing PVP content in the semi‐IPNs. In this study, we investigated the molecular mobility of the IPNs by means of dielectric relaxation spectroscopy; six relaxation processes were observed and indexed according the increase in the temperature range: the secondary β‐relaxations related to PU and PVP chains, an α‐relaxation due to the glass–rubber transition of the PU component, two α‐relaxations associated to the glass–rubber transitions of the PVP material, and an ionic conductivity relaxation due to the space charge polarization of PU. The temperature position of the α‐relaxation of PU was invariable in semi‐IPNs, as observed dynamic mechanical analysis measurements. However, the upper α‐relaxation process of PVP shifted to higher temperatures with increasing PVP content in the semi‐IPNs. We concluded that the investigated semi‐IPNs were two‐phase systems with incomplete phase separation and that the content of PVP in the IPNs governed the structure and corresponding properties of such systems through physical interactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1191–1201, 2003
Polymer‐immobilized N,N′‐bis(acetylacetone)ethylenediamine cobalt(II) Schiff base complex and its catalytic activity in comparison with that of its homogenized analogue
Authors: Gupta K. C. , Abdulkadir H. K. , Chand S.
Published: September 2003

For the preparation of a heterogenized N,N′‐bis(acetylacetone)ethylenediamine cobalt(II) Schiff base complex, first crosslinked polymer beads were prepared by the suspension copolymerization of styrene (48.97 mmol, 5.1 g), allyl chloride (48.97 mmol, 3.746 g), and divinyl benzene (DVB; 1.75 mmol, 0.228 g) in the presence of azobisisobutyronitrile (0.9 × 10−3 mmol, 0.15 g) as an initiator at 23 ± 0.1°C under an inert atmosphere. The copolymerization of styrene, allyl chloride in the presence of gelatin (0.75 g), bentonite (2.0 g), and boric acid (2.5 g) produced beads of different crosslinked densities corresponding to the concentration of DVB in the reaction mixture. The amount of allyl chloride in the prepared beads varied from 5.40 to 7.40 mmol g−1 of beads with the amount of DVB varying from 2.0 to 0.8 mmol in the reaction mixture. A quadridentate Schiff base (acen) was prepared with ethylenediamine (5.0 mmol, 0.3 g) and acetylacetone (10.0 mmol, 1.0 g), and it was used to obtain a homogenized and heterogenized Co(II)(acen)2 complex. The extent and arrangement of the Schiff base (acen) in the crosslinked beads depended on the availability of DVB in the reaction mixture. The amount of DVB in the reaction mixture influenced the extent of cobalt(II) ion loading, the degree of swelling, the porosity, and the pore size in the prepared beads. The beads (type IV) prepared with 1.75 mmol (0.228 g) of DVB in the reaction mixture showed a degree of swelling of 9.65% and efficiencies of loading and complexation for cobalt(II) ions of 49.4 and 85%, respectively, in comparison with beads obtained at other concentrations of DVB in the reaction mixture. The structure of free and polymer‐supported Co(II)(acen)2 complexes was verified with IR, UV, and magnetic measurements, which suggested a square planar geometry for the complexes under both conditions. The catalytic activities of the homogenized and heterogenized Co(II)(acen)2 complexes were compared by the evaluation of the rate constant (k) for the decomposition of hydrogen peroxide. The heterogenized Co(II)(acen)2 complex showed a high catalytic activity for the decomposition of hydrogen peroxide (k = 2.02 × 10−4 s−1) in comparison with the homogenized Co(II)(acen)2 complex (k = 4.32 × 10−6 s−1). The energy of activation for the decomposition of hydrogen peroxide with the heterogenized Co(II)(acen)2 complex was low (38.52 kJ mol−1) in comparison with that for the homogenized complex (73.44 kJ mol−1). In both cases, the rate of decomposition of hydrogen peroxide was directly proportional to the concentration of hydrogen peroxide and cobalt(II) ions. On the basis of experimental observations, a rate expression for the decomposition of hydrogen peroxide was derived. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1398–1411, 2003
The physical reasons for the homogeneous and nonhomogeneous reactions of haloid‐containing epoxy polymer curing
Authors: Kozlov G. V. , Bejev A. A. , Zaikov G. E.
Published: September 2003

The homogeneous reaction of crosslinked polymer curing proceeded in the medium with small density fluctuations, and the nonhomogeneous one proceeded in the medium with large density fluctuations. A nonhomogeneous curing reaction was simulated as proceeding in a fractal space. In this case, its rate was sharply reduced in comparison with a similar reaction in a Euclidean space. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1202–1205, 2003
Characterization of the weak link of wool fibers
Authors: Yu Weidong , Postle Ron , Yan Haojing
Published: September 2003

The variance of fiber morphology along a fiber and the natural and artificial flaws in the fiber structure represent the primary reasons for the weak link of fibers. Accordingly, the fiber weak link can be divided into two types, that is, the geometrical thinnest part and the structural weak point. Scanning electron microscopic observation was used to characterize the morphological features of the fiber weak points whose forms are the normal thin sections, natural flaws, and artificial damage. Both the fiber profile morphology and the tensile behavior of wool fibers have been measured using a single‐fiber analyzer (SIFAN) and an optical microscope with a CCD camera plus an XQ‐1 fiber tensile tester (OM + XQ). The results from the SIFAN and OM+XQ methods indicate that the fibers breaking at their minimum diameters represent only one part of the broken fibers. The percentage of this kind of breakage is in the range of 40–60%. A new approach is presented to identify the weak‐point breakage relying on the fiber tensile behavior. The experimental results show that the probabilities of weak‐point, normal, and thinnest‐part breakage evaluated by these methods approximate 40, 60, and slightly more than 80%, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1206–1212, 2003
Observation of morphology in EPDM/nylon copolymer thermoplastic vulcanizates by atomic force microscopy
Authors: Huang Hua , Ikehara Takayuki , Nishi Toshio
Published: September 2003

A thermoplastic vulcanizate (TPV) of an ethylene propylene diene terpolymer (EPDM) and nylon copolymer (PA) was prepared. Maleic anhydride‐grafted EPDM (EPDM‐g‐MAH) and MAH‐grafted EPR (EPR‐g‐MAH) were used as compatibilizers and sulfur was used as a curative. The phase morphology of EPDM/PA TPVs was investigated by atomic force microscopy (AFM). AFM images showed that, although there was a compatibilization reaction between EPDM‐g‐MAH and PA, phase inversion always existed for EPDM/EPDM‐g‐MAH/PA TPVs and the rubber phase could be finely dispersed in the PA matrix with an increasing compatibilizer content. For TPVs using EPR‐g‐MAH as a compatibilizer, three phases existed because of noncrosslinkability of EPR by sulfur. Crosslinked EPDM particles dispersed in a comatrix of PA and EPR‐g‐MAH could be observed by increasing the content of EPR‐g‐MAH to 26 wt %. For an EPR‐g‐MAH content of 26 wt %, the uncrosslinked EPR‐g‐MAH existing in the interface between crosslinked EPDM and PA tended to coalesce and thus resulted in a morphology of large rubber regions composed of small crosslinked particles. When the dosage of EPR‐g‐MAH was 52 wt %, the phase morphology of the blends changed to being one of PA and crosslinked EPDM particles dispersed in the MAH‐g‐EPR matrix. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1242–1248, 2003
Nonequilibrium particle morphology development in seeded emulsion polymerization. II. Influence of seed polymer Tg
Authors: Karlsson Lina E. , Karlsson Ola J. , Sundberg Donald C.
Published: September 2003

Most structured latex particles are formed in the nonequilibrium state as a result of the reaction kinetics proceeding faster than the phase separation kinetics. Of the many factors controlling such morphologies, the polarity and glass transition temperature (Tg) of the seed polymer are important. In order to study the direct effect of the seed polymer Tg on morphology, we produced a series of poly(methyl methacrylate)/poly(methyl acrylate) seed copolymers having glass points between 52 and 98°C, and particle sizes between 320 and 390 nm. We then used styrene as a second‐stage monomer reacting in both the batch and semibatch process modes, and utilized reaction temperatures (Tr) between 50 and 70°C. Monomer feed rates were varied between flooded and starve‐fed conditions. The equilibrium morphology for these composite particles is an inverted core–shell structure, but all morphologies obtained in our experiments were nonequilibrium. Under monomer starved conditions only core–shell structures were formed when (Tr−Tg) < 0, but significant penetration of the polystyrene into the acrylic core occurs when (Tr−Tg) > 15°C. These results are reasonably well predicted using the “fractional penetration” model developed earlier. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 905–915, 2003
Electrochemical preparation of polythiophene in acetonitrile solution with boron fluoride–ethyl ether as the electrolyte
Authors: Li Xiaohong , Li Yongfang
Published: September 2003

Polythiophene (PTh) films were prepared by the electrochemical polymerization of thiophene in acetonitrile solution with boron fluoride–ethyl ether (BFEE) as the electrolyte. The electropolymerization processes were investigated by cyclic voltammetry. The onset potential of the electropolymerization decreased dramatically with increasing BFEE proportion in the solution. The free‐standing PTh films obtained were characterized by Founier transform infrared spectroscopy, scanning electron microscopy, and X‐ray photoelectron microscopy. The influence of BFEE on the morphology and conductivity of the PTh films was also examined. The binary solvent solution consisted of acetonitrile (10 vol %) and BFEE (90 vol %), which turned out to be the optimal electrosythesis system, in which a current density of 1 mA/cm2 and a monomer concentration of 50 mM were the optimal conditions for electropolymerization. The PTh film obtained under the optimized conditions had a high tensile strength of 60 MPa and a high conductivity of 153 S/cm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 940–946, 2003
Comparison of the toughening mechanisms of poly(vinyl chloride)/chlorinated polyethylene and poly(vinyl chloride)/acrylonitrile–butadiene–styrene copolymer blends
Authors: Zhou Liling , Wang Xin , Lin Yusheng , Yang Jingyi , Wu Qiye
Published: September 2003

In this study, the influence of chlorinated polyethylene (CPE) and acrylonitrile–butadiene–styrene copolymer (ABS) on the mechanical properties of poly(vinyl chloride) (PVC)/CPE and PVC/ABS hybrids were examined. The experimental results show that the toughness of the hybrids could be modified greatly by the introduction of CPE or ABS. The microstructure and impact surfaces of the blends were investigated by scanning electron microscopy and transmission electron microscopy. ABS dispersed in the form of particles or agglomerates in the PVC matrix, and CPE tended to disperse as a net structure. In the tensile test, ABS initiated crazes as stress concentrators to toughen the PVC matrix, whereas CPE, with the PVC matrix together, caused a yield deformation by shear stress to form a shear band. The formation of crazes and shear bands benefited the toughening of PVC, but to the different extent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 916–924, 2003
Synthesis of thermally stable aromatic poly(imide amide benzimidazole) copolymers
Authors: Wang Huei‐Hsiung , Wu Shu‐Ping
Published: September 2003

3,3′‐Dinitrobenzidine was first reacted with excess m‐chlorophenyl acid to form a monomer with dicarboxylic acid end groups. Two types of aromatic dianhydrides (Pyromellitic diconhydride (PMDA) and 3,3′,4,4′‐sulfonyl diphthalic anhydride) were also reacted with excess 4,4′‐diphenylmethane diisocyanate to form polyimide prepolymers terminated with isocyanate groups. The prepolymers were further extended with the diacid monomer to form nitro groups containing aromatic poly(imide amide). The nitro groups in these copolymers were hydrogenated to form amine groups and then were cyclized at 180°C to form poly(imide amide benzimidazole) in poly(phosphoric acid), which acted as a cyclization agent. The resultant copolymers were soluble in sulfuric acid and poly(phosphoric acid), in sulfolane under heating to 100°C, and in the polar solvent N‐methyl‐2‐pyrrolidone under heating to 100°C with 5% lithium chloride. According to wide‐angle X‐ray diffraction, all the copolymers were amorphous. According to thermal analysis, the glass‐transition temperatures of the copolymers were 270–322°C. The 10% weight‐loss temperatures were 460–541°C in nitrogen and 441–529°C in air. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1435–1444, 2003
Online monitoring of the evolution of the number of particles in emulsion polymerization by conductivity measurements. I. Model formulation
Authors: Santos A. F. , Lima E. L. , Pinto J. C. , Graillat C. , McKenna T.
Published: September 2003

A conductivity meter is an inexpensive instrument that can easily be installed in polymerization reactors. This instrument can be used to monitor ionic species without time‐consuming calibrations. A probe is inserted into the media, providing in situ measurements of conductivity in real time. For emulsion polymerization reactions, the conductivity meter can respond to changes in the ionic surfactant concentration, allowing the determination of surfactant dynamics in the media. The surfactant concentration can then be related to the changes in the surface area of the polymer particle phase, which can be linked to nucleation or coagulation phenomena. In this study, a conductivity meter was coupled to a calorimetric reactor to provide in situ and online measurements of conductivity during the emulsion polymerization of styrene, with sodium dodecyl sulfate as an anionic surfactant and with potassium persulfate as a free‐radical initiator. A semiempirical model was built to describe the conductivity signal as a function of the latex composition and the reactor temperature. The model was inverted and combined with the available conductivity signal, conversion, and temperature measurements and was able to accurately predict the number of polymer particles in the latex and the surfactant concentrations in the many phases, without online measurements of the particle size. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1213–1226, 2003
Thermal degradation kinetics of poly(propylene carbonate) obtained from the copolymerization of carbon dioxide and propylene oxide
Authors: Liu Binyuan , Zhao Xiaojiang , Wang Xianhong , Wang Fosong
Published: September 2003

The kinetics of the thermal degradation of poly(propylene carbonate) (PPC) were investigated with different kinetic methods with data from thermogravimetric analysis under dynamic conditions. The apparent activation energies obtained with different integral methods (Ozawa–Flynn–Wall and Coats–Redfern) were consistent with the values obtained with the Kinssinger method (99.93 kJ/mol). The solid‐state decomposition process was a sigmoidal A3 type in terms of the Coats–Redfern and Phadnis–Deshpande results. The influence of the heating rate on the thermal decomposition temperature was also studied. The derivative thermogravimetry curves of PPC confirmed only one weight‐loss step. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 947–953, 2003
Miscibility and properties of blend membranes of waterborne polyurethane and carboxymethylchitin
Authors: Zeng Ming , Zhang Lina , Wang Niangui , Zhu Zhichao
Published: September 2003

We prepared a series of blend membranes by blending waterborne polyurethane (WPU) and carboxymethylchitin (CMCH) in aqueous systems. The effects of CMCH content on the miscibility, morphology, thermal stability, and mechanical properties of the blend membranes were investigated by dilute solution viscometry (DSV), Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction (WXRD), scanning electron microscopy, dynamic mechanical analysis (DMA), thermogravimetric analysis, ultraviolet (UV) spectroscopy, and tensile testing. The miscibility parameter of the WPU/CMCH aqueous solution obtained by DSV predicted that the blends of WPU and CMCH were miscible or partially miscible. Moreover, the partial miscibility of the blend membranes over the entire composition range were confirmed by FTIR, WXRD, DMA, and UV spectroscopy to support the conclusion from DSV. New hydrogen bonds were formed between CMCH and WPU in the blend membranes, resulting in strong intermolecular interactions. By inducing the CMCH, we improved the tensile strength, thermostability, and organic solvent resistance of the blend membranes significantly. Therefore, this study not only provided a novel way to prepare an environmentally–friendly material but also expanded the application of chitin and CMCH. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1233–1241, 2003
Novel water sorption behavior of emulsion blends
Authors: Robeson Lloyd M. , Hyder Ingrid Z.
Published: September 2003

As waterborne emulsions continue to replace their solvent‐based counterparts in various applications, the water resistance of cast films is attracting significant interest. The characterization of the water sorption kinetics and structure–property relationships related to water sorption is, therefore, an important area for investigation. In this study, the water sorption kinetics of emulsion blends were compared with those of their blend components. The investigated blends were at equal weight (dry basis) fractions for each emulsion. The initial water sorption rate for immiscible emulsion blends was found to be significantly higher than composite values of the constituents. This behavior was due to percolation networks in the blends because thermodynamic constraints prevented diffusion across the interface bordering dissimilar particles, leaving a interface enriched with water‐sensitive species. The peak water sorption for the immiscible emulsion blends was lower than the composite values because of the ability of the water‐sensitive species to rapidly diffuse out of the samples due to the percolation network. This behavior existed for room‐temperature‐cast samples and persisted as the time and temperature exposure was increased. Atomic force microscopy results clearly showed the potential for percolation networks in the blends. Higher glass‐transition emulsion polymers [e.g., poly(vinyl acetate)] exhibited similar behavior, and this indicated poor film formation like that for the immiscible emulsion blends. These results indicated that the degree of film formation was critical with respect to the water sorption characteristics of emulsion films. Immiscible emulsion blends were compared with miscible emulsion blends for which all constituents exhibited excellent film formation (unblended). The immiscible blends exhibited a significant difference in water sorption compared with the miscible blends because of the existence of percolation networks. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 933–939, 2003
Atom transfer radical polymerization of lauryl methacrylate
Authors: Xu Wenjian , Zhu Xiulin , Cheng Zhenping , Chen Jianying
Published: September 2003

The atom transfer radical polymerization (ATRP) of lauryl methacrylate (LMA) with an ethyl 2‐bromobutyrate/CuCl/N,N,N′,N″,N″‐pentamethyldiethylenetriamine initiation system was successfully carried out in toluene, and poly(lauryl methacrylate) with a low polydispersity (1.2 < weight‐average molecular weight/number‐average molecular weight < 1.5) was obtained. Plots of ln ([M])0/([M]) versus time and plots of the molecular weight versus conversion showed a linear dependence, indicating a constant number of propagating species throughout the polymerization. The rate of polymerization was 0.56‐order with respect to the concentration of the initiator and 1.30‐order with respect to the concentration of the Cu(I) catalyst. In addition, the effect of the solvent on the polymerization was investigated, and the thermodynamic data and activation parameters for the solution ATRP of LMA were reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1117–1125, 2003
Preparation and properties of polyelectrolyte complex sponges composed of hyaluronic acid and chitosan and their biological behaviors
Authors: Lee Sang Bong , Lee Young Moo , Song Kang Won , Park Moon Hyang
Published: September 2003

Polyelectrolyte complexes (PECs) composed of chitosan and hyaluronic acid (HA) were prepared in various pH regions and at different weight ratios. At low pHs, there was a strong ionic interaction between NH groups in chitosan and both COO− and COOH groups in HA due to the deprotonation of HA, whereas weak linkages were formed at high pHs because only the carboxyl groups of HA could interact with NH groups in chitosan. The formation of PECs resulted in a decrease in the crystallinity and thermal stability caused by the interactions between polyions. With variations in the degree of ionization of polyions at various pH conditions, novel PEC sponges were prepared by the freeze drying of PEC solutions. Furthermore, for the evaluation of the wound‐healing effect of PEC sponges with or without an antimicrobial agent (silver sulfadiazine), they were applied to a full‐skin defect of a Wistar rat in vivo. The histology and computerized morphometric analysis of the epidermal healing confirmed the proliferation of fibroblasts in the wound bed and a distinct reduction in infectious agents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 925–932, 2003
Thermooxidative degradation of methyl methacrylate‐graft‐natural rubber
Authors: Li Si‐Dong , Wang Chen , Xu Kui , Peng Zheng
Published: September 2003

The thermooxidative degradation of methyl methacrylate‐graft‐natural rubber (MG) at different heating rates (B) has been studied with thermogravimetric analysis in an air environment. The results indicate that the thermooxidative degradation of MG in air is a one‐step reaction. The degradation temperatures increase with B. The initial degradation temperature (To) is 0.697B + 350.7; the temperature at the maximum degradation rate, that is, the peak temperature on a differential thermogravimetry curve (Tp), is 0.755B + 368.8; and the final degradation temperature (Tf) is 1.016B + 497.4. The degradation rates at Tp and Tf are not affected by B, and their average values are 46.7 and 99.7%, respectively. The maximum thermooxidative degradation reaction rate, that is, the peak height on a differential thermogravimetry curve (Rp), increases with B. The relationship between B and Rp is Rp = 2.12B + 7.28. The thermooxidative degradation kinetic parameters are calculated with the Doyle model. The reaction energy (E) and frequency factor (A) change with an increasing reaction degree, and the variational trends of the two kinetic parameters are similar. The values of E and A increase remarkably during the initial stage of the reaction, then keep relevantly steady, and finally reach a peak during the last stage. The velocity constants of the thermooxidative degradation vary with the reaction degree and increase with the reaction temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1227–1232, 2003
Synthesis of new polymeric hindered amine light stabilizers: Performance evaluation in styrenic polymers
Authors: Singh R. P. , Patwa A. N. , Desai S. M. , Pandey J. K. , Solanky S. S. , Vishwa Prasad A.
Published: September 2003

Polymeric hindered amine light stabilizers (HALSs), in which the HALS functionality was attached to the terminal isocyanate chain end of poly(styryl‐co‐styryl isocyanate), were synthesized by a two‐step process. First, cinnamoyl azide was prepared and copolymerized with styrene by a free‐radical copolymerization method. Polymeric low‐molecular‐weight and high‐molecular‐weight 2,2,6,6‐tetramethyl‐4‐pipridinol‐graft‐poly(styryl‐co‐styryl isocyanate) and 4‐amino‐2,2,6,6‐tetramethyl piperidine‐graft‐poly(styryl‐co‐styryl isocyanate) were synthesized by a grafting method. The photodegradation and stabilization of different grades of high‐impact polystyrene (HIPS) were studied at 55°C in air at different time intervals, and the photostabilizing efficiency of polymeric HALSs was compared with conventional light stabilizers, such as 2,2,6,6‐tetramethyl‐4‐pipridinol and bis(2,2,6,6‐tetramethyl‐4‐piperidinyl)sebacate. Polymeric HALSs showed significant improvements in the photostabilization of HIPS. The solubility and diffusion coefficient of polymeric HALSs were studied. The morphological changes in HIPS caused by photooxidation were also studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1126–1138, 2003
Modification of acrylonitrile–butadiene–styrene terpolymer by grafting with maleic anhydride in the melt. I. Preparation and characterization
Authors: Qi Rongrong , Qian Junling , Zhou Chixing
Published: September 2003

The graft copolymerization of maleic anhydride (MAH) onto acrylonitrile–butadiene–styrene terpolymer (ABS) was carried out with dicumyl peroxide (DCP) and benzoyl peroxide (BPO) as the binary initiators and with styrene as the comonomer in the molten state. IR spectra confirmed that MAH was successfully grafted onto the ABS backbone. A reaction mechanism was proposed: the grafting most likely took place through the addition of MAH radicals to the double bond of the butadiene region of ABS. Influences such as the MAH concentration, the initiators and their concentrations, the reaction temperature, the rotating speed, and the comonomer concentration were studied. The results indicated that using styrene as a comonomer and DCP/BPO as binary initiators was beneficial for the graft copolymerization. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1249–1254, 2003
Particle features of poly(vinyl chloride) resins prepared by a new heterogeneous polymerization process
Authors: Bao Y. Z. , Brooks B. W.
Published: September 2003

The heterogeneous polymerization of vinyl chloride monomer (VCM), with n‐butane as the reaction medium, was used to prepare poly(vinyl chloride) (PVC) resins. The particle features of the resulting resins and the particle formation mechanism of the polymerization process were investigated. The PVC resins prepared by the new polymerization process had a volume‐average particle size comparable to that of suspension PVC resins and a lower number‐average particle size. From scanning electron micrographs, it could be seen that the new PVC resins had a regular particle shape and a smooth surface with no obvious skin. They also had a high porosity. The new PVC resins were composed of individual and loosely aggregated primary particles. The diameter of the primary particles in the top layer of the grains was smaller than that of the primary particles in the center part of the grains. On the basis of the particle features of these PVC resins, a particle formation mechanism for the new polymerization process was proposed. PVC chains precipitate from a VCM/n‐butane mixed medium to form primary aggregates at a very low conversion, and the primary aggregates of the PVC chains aggregate to form primary particles, which further aggregate to form grains. The primary particles and grains grow by the capture of newly formed PVC chains and their primary aggregates and by polymerization occurring inside the aggregates. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 954–958, 2003
Effects of NCO/OH ratio and catalyst concentration on structure, thermal stability, and crosslink density of poly(urethane‐isocyanurate)
Authors: Semsarzadeh M. A. , Navarchian A. H.
Published: September 2003

Poly(urethane‐isocyanurate)s were synthesized by reacting toluene diisocyanate and poly(propylene glycol) with various stochiometric ratios (1–3) in the presence of different concentrations of dibutyltin dilaurate (DBTDL) and ferric acetylacetonate (FeAA). The influence of the NCO/OH ratio and the catalyst type and concentration on the extent of urethane and isocyanurate formation were examined using Fourier transform IR spectroscopy. No trimer formation was observed in the presence of the FeAA catalyst. The percentage of the trimer group and the trimer/urethane content were found to be increased with increasing the stochiometric ratio or DBTDL concentration. The thermal decomposition of the copolyurethanes in an inert atmosphere was studied by means of thermogravimetry (TG). The TG curves showed three decomposition steps with the principal degradation temperature at about 355–385°C. The effects of the NCO/OH ratio, catalyst type and concentration, and heating rate on the thermal stability of the copolyurethanes were determined. The Flynn–Wall, Kissinger, and Ozawa methods were used to calculate the activation energies of thermal decomposition. The swelling behavior of solid copolyurethanes in toluene showed that, as the DBTDL concentration and/or NCO/OH ratio increased, the swelling ratio and average molecular weight between crosslinks were decreased whereas the crosslink density was increased. The sol fraction of solid copolyurethanes was examined and found to be reduced when the percentage of DBTDL or the stochiometric ratio was raised. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 963–972, 2003
Pressure‐dependent glass‐transition temperatures of poly(methyl methacrylate)/poly(styrene‐co‐acrylonitrile) blends
Authors: Wen Gangyao , An Lijia
Published: September 2003

The pressure‐dependent glass‐transition temperatures (Tg's) of poly(methyl methacrylate) (PMMA)/poly(styrene‐co‐acrylonitrile) (SAN) blends were determined by pressure–volume–temperature (PVT) dilatometry via an isobaric cooling procedure. The Gordon–Taylor and Fox equations were used to evaluate the relationships between the Tg's and compositions of the PMMA/SAN system at different pressures. The relationships were well fitted by the Gordon–Taylor equation, and the experimental data for Tg positively deviated from the values calculated with the Fox equation. Also, the influence of the cooling rate (during the PVT measurements) on Tg was examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 959–962, 2003
Hydrogenation of nitrile–butadiene rubber latex to form thermoplastic elastomer with excellent thermooxidation resistance
Authors: Xie Hong‐Quan , Li Xiao‐Dong , Guo Jun‐Shi
Published: September 2003

Hydrogenation of nitrile–butadiene rubber latex was carried out using hydrazine and hydrogen peroxide, with copper sulfate as catalyst and without pressurized hydrogen and organic solvent. A special inhibitor was used during hydrogenation to reduce gel formation. Various hydrogenation conditions were studied. The gel content of the hydrogenation product can be reduced to ∼15%, and hydrogenation degree can reach ∼87%. The hydrogenated product was characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. The hydrogenated product behaved as an oil‐resistant thermoplastic elastomer with excellent thermooxidation resistance, due to the absence of most double bonds and the presence of crystalline domains of polyethylene segments formed by hydrogenation of polybutadiene segments and nitrile groups. The higher the hydrogenation degree, the higher were the mechanical properties and thermooxidation resistance of the product. The product with a hydrogenation degree of 87% withstood thermooxidation quite well at 150°C for 65 h, maintaining ∼98% of its tensile strength and 96% of its ultimate elongation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1026–1031, 2003
A novel catalyst for the glycolysis of poly(ethylene terephthalate)
Authors: Troev K. , Grancharov G. , Tsevi R. , Gitsov I.
Published: September 2003

Poly(ethylene terephthalate) waste materials were depolymerized by ethylene glycol (EG), diethylene glycol (DEG), and propylene glycol (PG) in the presence of a novel catalytic system: titanium (IV)‐phosphate. The new catalyst was synthesized through a reaction of TiCl4 with triethyl phosphate (C2H5O)3P(O). It was found that the depolymerization of poly(ethylene terephthalate) fiber proceeds faster in the presence of titanium (IV)‐phosphate compared with compounds traditionally used in this process like Zn(OOCCH3)2. The oligomer distribution in the glycolysis products was studied by size‐exclusion chromatography. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1148–1152, 2003
Synthesis and characterization of novel copolymers of carboxyphenylmaleimide and methacrylates with trimethylsiloxy groups for deep‐UV photoresists
Authors: Chiang Wen‐Yen , Lee Ming‐Lo
Published: September 2003

N‐(4‐Carboxyphenyl) maleimide (CPMI), with high thermal stability structure, was synthesized from maleic anhydride and p‐aminobenzoic acid. Free‐radical copolymerization of CPMI and three comonomers (M‐1, M‐2, and M‐3) bearing a trimethylsiloxy group was performed at 60°C in the presence of azobisisobutyronitrile as an initiator in 1,4‐dioxane. Two different processes were adopted to prepare resists using these copolymers. The first one was to mix the dissolution inhibitor, o‐nitrobenzyl cholate, into the new copolymers. The second approach was to react the new copolymers with o‐nitrobenzyl bromide using 1,8‐diazabicyclo[5.4.0]undeca‐7‐ene in dimethylformamide. The cyclic maleimide group was responsible for the high thermal stability. After irradiation by a deep‐ultraviolet light and development with aqueous Na2CO3 (0.01 wt %), the developed patterns showed positive images and exhibited good adhesion to the silicon wafer without the use of any adhesion promoter. The resolution of the resists was at least 0.8 μm and the most effective factor for improving the etching selectivity was to increase the silicon content. We found that suitable amounts of silicon (about 14%) can drastically lower the etching rates of organic polymers; that is, an oxygen–plasma etching rate of 1 : 7.92 compared with hard‐baked HPR‐204. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1032–1037, 2003