Introduction of O-butyrylchitosan with a photosensitive hetero-bifunctional crosslinking reagent to silicone rubber film by radiation grafting and its blood compatibility

Based on an in vitro test for an improvement of the blood compatibility of silicone rubber (SR) films by grafting O-butyrylchitosan (OBCS), OBCS was covalently immobilized onto SR film surface using the photosensitive hetero-bifunctional crosslinking reagent, 4-azidobenzoic acid, which was previously bonded to OBCS by reaction between an acid group of the crosslinking reagent and a free amino group of OBCS. Surface properties of SR film were investigated by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), electron spectroscopy for chemical analysis (ESCA) and the water contact angle measurements. The blood compatibility of SR film was evaluated by platelet rich plasma (PRP) contacting experiments and the results were observed by scanning electron microscopy (SEM). The state of platelet adhesion was described. The suitable modifications could be carried out to tailor SR films biomaterial to meet the specific needs of different biomedical applications. These results suggest that the blood compatible of SR films/OBCS films show their suitability as potential biomaterials.     

Thermodynamical study on pressure-induced compatibility in UCST polymer-containing mixtures

The pressure effect on polymer-containing systems has been intensely studied in the past decades, and there has been increased interest in the effects of pressure on the miscibility of polymers[1—6]. One reason is the realization that such pressure effects could be important in many situations where such blends are used, e.g. when mixing a blend in an extruder or in forming arti-cles from a blend by injection molding. Another is the thermodynamics of typical polymer blends that are understood…     

Structure–property relationships in modified natural rubber latexes grafted with methyl methacrylate and vinyl neo‐decanoate

A series of modified natural rubber latexes (NRLs) grafted with poly(methyl methacrylate) (PMMA) were prepared by seeded emulsion polymerization with NRL as the seed polymer. Two different redox systems, cumene hydroperoxide (CHP)/tetraethylene pentamine (TEPA) and tert‐butyl hydroperoxide (t‐BHP)/TEPA, were used to initiate polymerization, and phase mixing was promoted by the addition of vinyl neo‐decanoate (VneoD). The CHP/TEPA system was more efficient than t‐BHP/TEPA for the grafting of secondary polymers in modified natural rubber (NR). The enhanced phase mixing in the presence of VneoD was attributed to the solubility parameter of the VneoD‐rich methyl methacrylate–VneoD copolymer formed late in the reaction, lying between that of PMMA and NR, and the extent to which this polymer was grafted to the NR backbone. The viscoelastic properties of the polymers were investigated as a function of composition, temperature, and frequency; changes in viscoelastic behavior consistent with the presence of a high‐T_g PMMA phase (where T_g is the glass‐transition temperature) were observed. This suggested a degree of phase mixing that increased with increasing VneoD content and increasing flux of oxygen‐centered radicals within the NR particles. More phase mixing resulted in poorer film formation, which was consistent with the localization of a high‐T_g secondary polymer phase near the particle surface. The apparent concentration of PMMA near the surface of the particles was also observed with transmission electron microscopy. The localization of PMMA near the particle surfaces was consistent with the presumed locus of radical generation in these systems: the redox couple used to initiate the polymerization consisted of an oil‐soluble hydroperoxide and a water‐soluble amine that reacted predominantly at the water/particle interface. The viscoelastic properties of the modified NRLs that were prepared suggest that these synthetic procedures provide a means of controlling phase mixing and branching, such as for improving the suitability of these modified rubbers in pressure‐sensitive‐adhesive formulations. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 809–822, 2002; DOI 10.1002/pola.10165     

MECHANICAL PROPERTIES OF OZONIZED HDPE FILLED WITH SERICITE-TRIDYMITE-CRISTOBALITE

The mechanical properties of ozonized high density polyethylene (HDPE) blended with sericite-tridymite-cristobalite (STC) were studied in this paper. The experimental results show that some oxygen containing polar groups are introduced on the molecular chain of HDPE through ozonization, the compatibility between HDPE and STC is thus improved, the mechanical properties of the blend are markedly enhanced. Compared with untreated HDPE/STC (60/40) blend, the yield strength and notched impact strength of ozonized HDPE/STC (60/40) blend are increased from 27.0MPa to 29.5MPa and from 2.8kJ/m^2 to 13.3kJ/m^2, respectively, the notched impact strength is close to that of HDPE (13.6kJ/m^2),the yield strength is in excess of 3.9MPa of that of HDPE. The yield strength and notched impact strength will be further increased to 30.7MPa and 32.4kJ/m^2 in case the ozonized HDPE is blended with STC pretreated with silane coupling agent.     

乙丙橡胶/聚丙烯共混体系的界面相互渗透

本文用X射线衍射仪、差热分析仪、动态力学扭摆仪和测定有效网链密度等方法,研究了乙丙橡胶/聚丙烯(EPDM/PP)共混体系中PP的非晶部分和EPDM的相互渗透。EPDM和PP不具有互溶性,但PP的非晶部分和EPDM两相界面处有较强的相互渗透,即部分互容性。有效链密度和性能间关系的数据表明,共混体系不一定存在硫化胶那样的对应关系。     

固相法氯化聚乙烯增韧聚氯乙烯的研究Ⅱ．CPE的氯含量及共混方式与PVC／CPE相容性的关系

研究了聚氯乙烯（ＰＶＣ）与固相法氯化聚乙烯（ＣＰＥ）的相容性与氯含量、共混方式以及ＣＰＥ链结构的关系。动态力学性能表明ＰＶＣ／ＣＰＥ为部分相容体系，ＣＰＥ中类似ＰＶＣ的链段与ＰＶＣ形成相间过渡层，共混方式影响共混体系的相容程度。透射电镜结果表明ＣＰＥ呈连续网络结构分布于ＰＶＣ粒子表面。共混条件一定时，共混物的抗张强度随相容性的改善而增加。     

层层自组装技术在生物医用材料领域中的应用研究进展

基于聚电解质阴阳离子交替组装的层层自组装技术由于可在温和的条件下实现多种生物大分子在材料表面的固定,并通过对组装条件的控制实现多种生物功能,已成为生物医用材料表面设计的重要手段。本文对层层自组装技术在构建血液相容性界面、组织工程表面、药物控释涂层等生物医用材料领域的应用研究进行了比较系统的阐述。     

Lightweight electromagnetic shields using optimized polyaniline composites in the microwave band

A genetic algorithm (GA) was used to optimize a multilayer electromagnetic shield of polyaniline (PANI)–polyurethane (PU) conducting composites in the microwave band. First, the electronic properties of freestanding films with different mass fractions of polyaniline were studied. A very low percolation threshold (0.2%) was found, with a maximum of conductivity of 10⁴ S/m. Second, the electromagnetic shielding effectiveness of the films were investigated in the X and Ku bands (8.2–18 GHz), showing an attenuation increase of 1–40 dB with the mass fraction of polyaniline in the blends. Then, the electromagnetic shielding properties of multi‐layered PAni–PU composites were investigated in order to obtain an attenuation superior to 40 or 80 dB, depending on the application. To improve the performances of the electromagnetic shields, three‐layered PAni–PU composites were made, using an optimization method. The intrinsic physical parameters of the composites were used as a database for the optimization calculation. The optimization results showed that materials with a thickness of <500 µm could answer many industrial or military shielding applications. As the electronic properties can be tuned easily with the mass fraction of polyaniline in the blends, conducting multi‐layered composite materials can be made following the results of the optimization. Their electromagnetic shielding effectiveness was measured, showing good agreement between the measurements and modeling. These results demonstrated that the genetic algorithm allows us to conceive lightweight and high performance electromagnetic shields using intrinsically conducting polymers. The mass per unit of surface of the shield was <200 g/m², giving potential applications in the aeronautics domain. Copyright © 2007 John Wiley & Sons, Ltd.     

ANALYSIS OF INHOMOGENEOUS FINITE STRAIN FIELDS IN THE EARTH''''S CRUST

This paper proposes the approximate methods of calculation for research on inhomogeneous finite strain fields in geologic bodies by means of the "Principal Axis" theory of continuum mechanics. The methods are to obtain the principal strain orientations at finite points in the earth's crust based on the information and data provided by the actual strain measurements of deformation marked objects in the field, or by the research on crystalline fabrics in rocks, and then to obtain two sets of smooth orthogonal principal strain trajectories through mathematical treatments. A network composed of two sets of orthogonal curves shows the deformation character of the rock, and correspondent strain components satisfy compatibility conditions. The curvatures of curves are used to describe the compatibility conditions in this paper. An analytic solution of a strain field is obtained when the two sets of lines can be simulated by analytic function; the magnitudes of principal strains at every point may be obtained b     

离子聚合物在Nylon－1010／PP共混物中的增容作用

离子聚合物在Ｎｙｌｏｎ－１０１０／ＰＰ共混物中的增容作用曲桂杰，刘景江（中国科学院长春应用化学研究所长春１３００２２）关键词聚丙烯，Ｎｙｌｏｎ－１０１０，离子聚合物，增容选择离子聚合物作为高聚物共混的增容剂，通过离子间的相互作用可达到增容效果［１］。...