检索结果-内蒙古大学图书馆

Crosslinking of chitosan fibers with dialdehydes: Proposal of a new reaction mechanism

Journal of polymer science 1999年第11期37卷

作者： Jonathan Z. Knaul Samuel M. Hudson Katherine A. M. Creber Department of Chemistry and Chemical Engineering Royal Military College PO Box 17000 Station Forces Kingston Ontario K7K 7B4 Canada Fiber and Polymer Science Program Box 8301 Centennial Campus North Carolina State University Raleigh North Carolina 27695-8301

A highly deacetylated chitosan from shrimp with a degree of deacetylation of 95.28 ± 3.03% was prepared and spun into a monofilament fiber using a solution of 4% (w/v) chitosan in 4% (v/v) aqueous acetic acid. Samples of the spun fibers were immersed in aqueous solutions containing glutaraldehyde and glyoxal, and subsequently washed and dried. When the concentration of crosslinking agent was varied at room temperature over a constant time of 1 h, dry mechanical properties improved up to a point after which increasing concentrations resulted in degradation. Immersion time was also varied between 1 and 60 min at 25.8°C, and temperature was varied between 25.8 and 70.0°C, at fixed concentrations of both glyoxal and glutaraldehyde. It was demonstrated that mechanical improvements might be rendered at higher temperatures over lesser times. However, it was also shown that at higher temperatures, fiber mechanical properties would begin to diminish. Chitosan films were subjected to similar treatments in aqueous crosslinking solutions. Fourier transform infrared data (FTIR) on the films suggest that some interaction is occurring between the glutaraldehyde or glyoxal and the amine group on the chitosan backbone. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1079–1094, 1999

关键词： chitosan fiber crosslinking mechanical films FTIR wet spinning

来源：评论

学校读者我要写书评

暂无评论

Miscibility of polyimide with polymeric primer and its influence on adhesion of polyimide to the primed copper metal: Effect of precursor origin

引用

Journal of polymer science 1999年第19期37卷

作者： J. Yu M. Ree T. J. Shin X. Wang W. Cai D. Zhou K.-W. Lee Department of Chemistry Polymer Research Institute and School of Environmental Engineering Pohang University of Science & Technology San 31 Hyoja-dong Pohang 790-784 Korea Department of Applied Chemistry Harbin Institute of Technology Harbin Heilongjiang Province 150001 China Department of Electrical Engineering Harbin Institute of Technology Harbin Heilongjiang Province 150001 China IBM Research T. J. Watson Research Center Yorktown Heights New York 10598

Poly(amic acid) (PAA) and poly(amic diethyl ester) (PAE) precursors of poly(4,4′-oxydiphenylene biphenyltetracarboximide) (BPDA-ODA PI) were synthesized. Miscibility behaviors of these precursors with poly(arylene ether benzimidazole) (PAEBI), which is a good adhesion primer for copper metal, were investigated in N -methyl-2-pyrrolidone (NMP) as well as the condensed state and the imidized state. For the PAA/PAEBI blend over the whole range of compositions, no cloud point was measured either in the NMP solution, the condensed state, or the imidized state. Furthermore, no aggregation of PI chains in the blend films was detected by X-ray diffraction. These results indicate that the PAA and PAEBI are completely miscible at the molecular level, consequently leading to the miscible PI/PAEBI blend. This miscibility might result from the strong interaction via the complex formation of imidazole groups of the PAEBI and carboxylic acid groups of the PAA precursor. In contrast, the miscibility of PAE/PAEBI blend in NMP was limited up to a concentration of 13.5–36.3 wt %, leading to a phase separation in the soft-baked and imidized blend. The blend films rich with one component were optically transparent, which might be due to the phase-separated domains much smaller than 1 μm. The immiscibility might result from the relatively weak interactions of imidazole groups of PAEBI with both the ester and amide linkages in the PAE precursor. The difference in the miscibilities of PAEBI with the PAA and PAE precursors was reflected in the adhesion of PI/PAEBI/copper joints: higher miscibility gave higher adhesion strength. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2806–2814, 1999

关键词： poly(arylene ether benzimidazole) primer polyimide precursor origin miscibility phase diagram adhesion copper peel test

来源：评论

学校读者我要写书评

暂无评论

Clustering in carboxylated polysulfone ionomers: A characterization by dynamic mechanical and small-angle X-ray scattering methods

引用

Journal of polymer science 1999年第22期37卷

作者： Diep Nguyen Joon-Seop Kim Michael D. Guiver Adi Eisenberg Department of Physics Building 750 Brookhaven National Laboratory Upton New York 11973 Department of Polymer Science and Engineering Chosun University Kwangju 501-600 Korea Institute for Chemical Process and Environmental Technology National Research Council Ottawa Ontario K1A 0R6 Canada Department of Chemistry McGill University Montreal Quebec H3A 2K6 Canada

The dynamic mechanical properties and morphology of carboxylated polysulfone ionomers were investigated by dynamic mechanical thermal analysis and small-angle X-ray scattering (SAXS) techniques. It was found that at 25 mol % of ions, ionomers show two glass transitions: one at about 200 °C (the matrix T g ) and the other at about 235 °C (the cluster T g ). It was also found that with increasing ion content up to about 37 mol %, the matrix T g shifted to higher temperatures and the size of tan δ peak decreased. The cluster T g did not change. From the results, it is suggested that even at high ion content, the ionomers contain a significant amount of unclustered material, but that the increase in the ion content does not increase the amount of clustered material. SAXS profiles showed the ionic peak, which represents the presence of multiplets in the cluster regions. In addition, the difference in the matrix and cluster T g 's of this ionomer system was found to be about 35°. Thus, it is postulated that ionic group aggregation is subject to steric hindrance owing to the bulkiness of benzene ring, and tension on polymer chains surrounding the multiplet owing to chain rigidity, which limit the size and stability of the multiplet significantly. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3226–3232, 1999

关键词： dynamic mechanical, small-angle X-ray scattering ionomers carboxylated polysulfone

来源：评论

学校读者我要写书评

暂无评论

Spinodal Dewetting of Thin polymer Films

引用

Physical Review Letters 1998年第6期81卷 1251-1251页

作者： R. Xie A. Karim J. F. Douglas C. C. Han R. A. Weiss Polymer Science Program and Department of Chemical Engineering University of Connecticut Storrs Connecticut 06269 Polymers Division National Institute of Standards and Technology Gaithersburg Maryland 20899

Dewetting of polystyrene films on a silicon substrate is investigated as a function of film thickness h. We observe the nucleation of holes in the early stage of dewetting for relatively thick films (h>100Å), as observed previously, but the breakup of thinner films occurs through the growth of uniformly distributed surface undulations (“spinodal dewetting”). The average amplitude δh of these undulations increases exponentially up to the film rupture point where δh becomes comparable to h, as predicted by a capillary wave instability model.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Contributory presentations/posters

引用

Journal of Biosciences 1999年第1期24卷 33-198页

作者： N. Manoj V. R. Srinivas A. Surolia M. Vijayan K. Suguna R. Ravishankar R. Schwarzenbacher K. Zeth Diederichs G. M. Kostner A. Gries P. Laggner R. Prassl Madhusudan Pearl Akamine Nguyen-huu Xuong Susan S. Taylor M. Bidva Sagar K. Saikrishnan S. Roy K. Purnapatre P. Handa U. Varshney B. K. Biswal N. Sukumar J. K. Mohana Rao A. Johnson Vasantha Pattabhi S. Sri Krishna Mira Sastri H. S. Savithri M. R. N. Murthy Bindu Pillai Kannan M. V. Hosur Mukesh Kumar Swati Patwardhan K. K. Kannan B. Padmanabhaa S. Sasaki-Sugio M. Nukaga T. Matsuzaki S. Karthikevan S. Sharma A. K. Sharma M. Paramasivam P. Kumar J. A. Khan S. Yadav A. Srinivasan T. P. Singh S. Gourinath Neelima Alam A. Srintvasan Vikas Chandra Punit Kaur Ch. Betzel S. Ghosh A. K. Bera S. Bhattacharya S. Chakraborty A. K. Pal B. P. Mukhopadhyay I. Dey U. Haldar Asok Baneriee Jozef Sevcik Adriana Solovicova K. Sekar M. Sundaralingam N. Genov Dong-cai Liang Tao Jiang Ji-ping Zhang Wen-rui Chang Wolfgang Jahnke Marcel Blommers S. C. Panchal R. V. Hosur Bindu Pillay Puniti Mathur S. Srivatsun Ratan Mani Joshi N. R. Jaganathan V. S. Chauhan H. S. Atreya S. C. Sahu K. V. R. Chary Girjesh Govil Elisabeth Adjadj Éric Quinjou Nadia Izadi-Pruneyre Yves Blouquit Joël Mispelter Bernadette Heyd Guilhem Lerat Philippe Milnard Michel Desmadreil Y. Lin B. D. Nageswara Rao Vidva Raghunathan Mei H. Chau Prashant Pesais Sudha Srivastava Evans Coutinho Anil Saran Leizl F. Sapico Jayson Gesme Herbert Lijima Raymond Paxton Thamarapu Srikrishnan C. R. Grace G. Nagenagowda A. M. Lynn Sudha M. Cowsik Sarata C. Sahu S. Chauhan A. Bhattacharya G. Govil Anil Kumar Maurizio Pellecchia Erik R. P. Zuiderweg Keiichi Kawano Tomoyasu Aizawa Naoki Fujitani Yoichi Hayakawa Atsushi Ohnishi Tadayasu Ohkubo Yasuhiro Kumaki Kunio Hikichi Katsutoshi Nitta V. Rani Parvathy R. M. Kini Takumi Koshiba Yoshihiro Kobashigawa Min Yao Makoto Demura Astushi Nakagawa Isao Tanaka Kunihiro Kuwajima Jens Linge Seán O. Donoghue Michael Nilges G. Chakshusmathi Girish S. Ratnaparkhi P. K. Madhu R. Varadarajan C. Tetreau Molecular Biophysics Unit Indian Institute of Science Bangalore India Austrian Academy of Sciences Institute of Biophysics and X-ray Structure Research Graz Austria Faculty of Biology University of Konstanz Germany Institute of Medical Biochemistry University of Graz Austria Howard Huges Medical Institute Department of Chemistry & Biochemistry University of California La Jolla USA Department of Chemistry & Biochemistry University of California San Diego La Jolla USA Molecular Biophysics Unit India Department of Microbiology &Cell Biology Indian Institute of Science Bangalore India Macromolecular Structure Laboratory NCI - Frederick Cancer Research and Development Center ABL - Basic Research Program Frederick USA Department of Crystallography and Biophysics University of Madras Chennai Biochemistry Department Indian Institute of Science Bangalore India Condensed Matter Physics Division B.A.R.C. Trombay Mumbai Condensed Matter Physics Division Bhabha Atomic Research Centre Trombay Mumbai IMCB The University of Tokyo Tokyo Japan Mitsubishi Chemical Corporation Yokohama Research Center Yokohama Japan Faculty of Pharmaceutical Sciences Chiba University Chiba Japan Department of Biophysics All India Institute of Medical Sciences New Delhi India Department of Biophysics All India Institute of Medical sciences New Delhi India Institüt Physiologische Chemie Hamburg Germany Biophysics Department Bose Institute Calcutta India Slovak Academy of Sciences Institute of Molecular Biology Bratislava Slovakia Indian Institute of Science Bioinformatics Centre Bangalore Departments of Chemistry and Biochemistry Biological Macromolecular Structure Center USA Bulgarian Academy of Sciences Institute of Organic Chemistry Sofia Bulgaria Chinese Academy of Sciences Institute of Biophysics Beijing China Novartis Pharma AG Preclinical Research Basel Switzerland Department of Chemical Sciences Tata Institute of Fundamental Research Mumbai India Solid State Physics Div

来源：评论

学校读者我要写书评

暂无评论

Impact strength and fracture surfaces of interfaces between polyethylene and polypropylene and some ethylene‐containing copolymers

引用

Journal of Applied polymer science 1998年第11期64卷

作者： Ruth L. Mcevoy Sonja Krause Department of Chemistry and Polymer Science and Engineering Program Rensselaer Polytechnic Institute Troy New York 12180‐3590

The impact strength of annealed interfaces between high‐density polyethylene (HDPE), low‐density polyethylene (LDPE), and polypropylene (PP) and some ethylene‐co‐vinyl acetate (EVA) and ethylene‐co‐acrylic acid (EAA) copolymers was obtained using the Notched Izod test. The impact strengths of EVA‐HDPE, EVA‐LDPE, and EVA‐PP interfaces using EVA copolymers with 9 to 27.5 wt % vinyl acetate (VA), and of EAA‐PP interfaces using EAA with 3 to 20 wt % acrylic acid (AA), were all equal to or greater than those of the homopolymer used. However, the impact strengths of EAA‐HDPE and EAA‐LDPE interfaces were all lower than those of pure HDPE or LDPE, with the exception of 3EAA‐LDPE. Scanning electron micrographs showed the presence of fibrils and/or voids, mostly on those copolymer‐homopolymer fracture surfaces which had high impact strength. X‐ray photoelectron spectroscopy of the fracture surfaces showed a greater calculated percentage of AA or VA on both the copolymer and homopolymer sides of the interface than in the bulk for most samples at 15 Å penetration. This greater calculated percentage of AA or VA is probably due to chain scission during sample preparation or fracture, which results in additional acid or alcohol groups at the surface that are calculated as increased VA or AA content. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2221–2235, 1997

关键词： fracture surfaces impact strength polyethylene polypropylene ethylene‐vinyl acetate copolymers ethylene‐acrylic acid copolymers

来源：评论

学校读者我要写书评

暂无评论

Electrical properties of block copolymers containing silver nanoclusters within oriented lamellar microdomains

引用

Journal of Applied polymer science 1998年第4期65卷

作者： B. H. Sohn R. E. Cohen Program in Polymer Science and Technology Massachusetts Institute of Technology Cambridge Massachusetts 02139 Department of Chemical Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139

Films containing silver nanoclusters within a lamellar morphology were obtained via postprocessing reduction of the silver‐containing regions of block copolymers synthesized by ring opening metathesis polymerization. Solution‐cast films (0.1 mm thickness) of the block copolymer exhibited an oriented lamellar morphology with lamellar normals perpendicular to the film plane. The slightly anisotropic dielectric properties, perpendicular and parallel to the film plane, were investigated by direct measurement and by model calculations. The conductivity was highly anisotropic, differing by at least four orders of magnitude in directions parallel and perpendicular to the film plane. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 723–729, 1997

关键词：

来源：评论

学校读者我要写书评

暂无评论

The development of conductive composite surfaces by a diffusion-limitedin situpolymerization of pyrrole in sulfonated polystyrene ionomers

引用

Journal of polymer science 1998年第2期35卷

作者： M. Cristina De Jesus R. A. Weiss Yuping Chen Polymer Science Program and Department of Chemical Engineering University of Connecticut Storrs Connecticut 06269-3136 State Key Laboratory of Engineering Plastics Institute of Chemistry Academia Sinica Beijing 10080 China

Electrically conductive composite surfaces were prepared by a diffusion-controlled in situ polymerization of pyrrole in the surface layer of sulfonated polystyrene ionomer films. Premolded films of the ionomer sulfonic acid derivatives were sequentially immersed in aqueous solutions of pyrrole and FeCl 3 , and polymerization occurred only where both the monomer and the oxidant were present. The penetration of the polypyrrole (PPy) into the film was controlled by varying the immersion time in the monomer solution. The amount of PPy produced depended on the immersion time of the film in the monomer and the degree of sulfonation of the ionomer. Surface conductivities of 10 −4 -10 −1 S/cm were achieved with PPy concentrations from 2 to 22 wt % and composite layers as thin as 15 μm. Intermolecular interactions occurred between PPy and the ionomer by proton transfer. Incorporation of PPy also increased the tensile strength of the ionomer film, significantly increased its modulus above T g , and inhibited melt flow. © 1997 John Wiley & Sons, Inc.

关键词： polypyrrole electrical conductivity composite surfaces

来源：评论

学校读者我要写书评

暂无评论

Sedimentation‐resistant electrorheological fluids based on PVAL‐coated microballoons

引用

Journal of Applied polymer science 1998年第3期65卷

作者： Mancun Qi Montgomery T. Shaw Department of Chemical Engineering University of Connecticut Storrs Connecticut 06269‐3136 Polymer Science Program Institute of Materials Science University of Connecticut 97 North Eagleville Road U‐136 Storrs Connecticut 06269‐3136

Sedimentation is often a problem in electrorheological (ER) fluids featuring solid particles suspended in a low‐density hydrocarbon oil. This problem was addressed by synthesizing particles comprising silica microballoons coated with PVAL using a salt‐induced coacervation process. The ER performance of the fluids based on these particles was equivalent to prototypical commercial fluids, both with respect to current leakage and shear stress under steady simple shear flow. For comparing diverse fluids as to these practical characteristics, a dimensionless ER effectiveness number, Er, was proposed: Er = σγ˙/ EJ where σ is the shear stress, γ˙ is the electric field, and J is the current. The resulting uniform coatings were also found to impart a degree of resistance to breakage. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:539–547, 1997

关键词： ER fluids electrorheology PVAL‐coated microballoons ER effectiveness number sedimentation attrition

来源：评论

学校读者我要写书评

暂无评论

A relationship between the glass transition temperature (Tg) and fractional conversion for thermosetting systems

引用

Journal of Applied polymer science 1998年第1期64卷

作者： R. A. Venditti J. K. Gillham Department of Wood and Paper Science North Carolina State University Box 8005 Raleigh North Carolina 27695‐8005 Polymer Materials Program Department of Chemical Engineering Princeton University Princeton New Jersey 08544

An equation, based on thermodynamic considerations to relate the glass transition temperature, T g , to compositional variation of a polymer system, is adapted in this article for modeling the T g vs. fractional conversion ( x ) relationship of reactive thermosetting systems. Agreement between the adapted equation and experimental T g vs. x data is found for several thermosetting crosslinking systems (i.e., epoxies and cyanate ester/polycyanurate) as well as for reactive thermosetting linear polymer systems (i.e., polyamic acid and esters to polyimides). The equation models the experimentally obtained T g vs. x behavior of thermosetting systems which include competing reactions. Agreement for widely varying molecular structures demonstrates the generality of the equation. The entire T g vs. x relationship can be predicted for a thermosetting material by using the T g vs. x equation and the values of the initial glass transition temperature, T g 0 , the fully reacted system glass transition temperature, T g∞ , and the ratio of the change in specific heat from the liquid or rubbery state to the glassy state (Δ c p ) at T g 0 and T g∞ , Δ c p∞ /Δ c p 0 . The values of T g 0 , T g ∞ , and Δ c p∞ /Δ c p 0 can be measured generally from two differential scanning calorimetric experiments. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 3–14, 1997

关键词：

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：