共查询到20条相似文献,搜索用时 125 毫秒
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医用高分子材料的生物相容性问题逐步引起人们的重视[1].除合成相容性好的材料外,另一个途径是对现有高分子材料进行改性以提高其生物相容性,其中表面改性因其对材料本体的影响小,成为医用高分子材料研究的一个热点.Ruckenstein[2]最早利用溶液法改... 相似文献
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微波等离子体诱导聚乙烯表面接枝甲基丙烯酸甲酯 总被引:5,自引:0,他引:5
聚乙烯(PE)通常作为性能优良的薄膜材料被广泛使用,但由于其表面能低,导致表面亲水性差,粘结性弱,染色性能、印刷性能等很不理想[1,2].在高分子材料的各种表面改性方法中,接枝共聚是一种很有效的途径[3~5].本文探讨了用微波冷等离子体激活聚乙烯表面... 相似文献
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壳多糖与丙烯酸丁酯的乳液接枝共聚研究 总被引:10,自引:0,他引:10
以十二烷基苯磺酸钠为乳化剂,过硫酸钾-亚硫酸氢钠为引发剂,研究了壳多糖与丙烯酸丁醋的乳液共聚合,结果表明当[K2S2O8]=[NaHSO3]=2.57×10-3mol·1-1,[BA]=0.68mol.1-1,[Chitosan]=19.2g·l-1,在70℃下反应5小时,共聚反应的接技率和接枝效率均较高.用红外光谱,差热分析,X射线衍射,扫描电镜对接技共聚物进行了表征,此外测试了共聚物胶乳成膜的机械性能,表明用丙烯酸丁酯对壳多糖进行接枝改性,可提高壳多糖的韧性,扩大其应用范围. 相似文献
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半菁染料是人们制造LB膜的材料之一.近年来,为得到电导率较高的薄膜,电荷转移络合物的LB膜受到重视[1].实验证明,有机材料的LB膜经化学修饰或改性以后,电导率大大增加.化学工作者常将有机染料分子用来修饰电极,在光电化学、电催化等方面有较好的效果,因而,受到人们极大的关注.化学工作者已成功地制备出许多染料化学修饰电极,研究膜修饰电极的电化学行为[2,3],而用循环伏安法和光谱技术对有机染料的电化学行为研究得较少[4,5].本文对4 [2 (4 N,N 二甲基苯胺基 )乙烯基]吡啶氧化物这个新改性的半菁化… 相似文献
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含羧酸共生稀土光敏剂的低密度聚乙烯膜紫外光氧化降解 总被引:3,自引:0,他引:3
含羧酸共生稀土光敏剂的低密度聚乙烯膜紫外光氧化降解林宜超(福建省测试技术研究所福州350003)近年来,许多作者先后研究并开发出含硬脂酸铈(CeSt3)光敏剂的可控光降解低密度聚乙烯(LDPE)[1,2]、高密度聚乙烯[3]、聚丙烯[4]、聚苯乙烯... 相似文献
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MgCl_2负载双金属复合催化剂制备宽分子量分布聚乙烯 总被引:1,自引:0,他引:1
聚乙烯的分子量和分子量分布对其熔体的流变性能和产品的力学性能有显著影响.分子量分布的变化,尤其是分子量分布末端部位的变化,都会对材料的注塑行为产生大的影响[1].为了控制Ziegler催化剂制备的聚乙烯分子量分布而改善聚合工艺的报道很多[2~4],工业生产中可利用多步聚合工艺来获得宽分子量分布的聚乙烯[5,6],但这种方法工艺复杂,成本高.美国UCC公司利用复合的TiV和ZrV催化剂在气相法Unipol工艺装置上首次成功的合成出了双峰高分子量聚乙烯产品[7,8],由于采用Unipol生产工艺… 相似文献
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Menashe Tahan Albert Zilkha 《Journal of polymer science. Part A, Polymer chemistry》1969,7(7):1815-1824
Graft polymers of polyethylene oxide on various starches were obtained by anionic graft polymerization of ethylene oxide on the starch alkoxide derivatives. The polyalkoxides were prepared by reaction of potassium naphthalene with starch in DMSO solution. It was found that increase of monomer or alkoxide concentration led to transformation of the grafts from solids to syrups. Rice starch, having a more complex structure than soluble starch or wheat starch, led to graft polymers having higher melting ranges than the others. The graft polymers were very soluble in water or methanol. 相似文献
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淀粉接枝丙烯酸乙酯及其增容性 总被引:5,自引:0,他引:5
研究了在挤出机中采用高温和剪切力的作用直接引发淀粉与丙烯酸乙酯的接枝共聚合反应.讨论了反应条件对接枝反应的影响,研究了接枝物在淀粉与聚乙烯共混物中的增容作用.实验结果表明,高温和剪切力可以引发淀粉与丙烯酸乙酯的接枝共聚合反应.接枝物作为增容剂,可以明显地改善淀粉与聚乙烯共混物的力学性能和流变性能. 相似文献
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The acid-catalyzed reaction of dialdehyde starch with diethylene glycol and polyethylene oxide-400 under anhydrous conditions was studied as a new approach to the preparation of graft polymers of polyalkylene oxides on starch, the attachment of the side chains being through acetal linkages. The reaction was carried out in DMF in the presence of p-toluene sulfonic acid. It was found that increasing the reaction temperature, the diol concentration, or the reaction time led to an increase in the degree of grafting, as seen from the decrease in the dicarbonyl content of the products. Fusible graft polymers, soluble in water and in organic solvents, were obtained. 相似文献
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The accessibility of starch in polyethylene starch blends was investigated by computer simulation, percolation theory, and acid hydrolysis experiments. The object of this work was to model the bilateral invasion of microbes in polyethylene-starch blends as a function of starch concentration (p), and thickness of the material. It was found that computer simulations in three dimensions were in agreement with both percolation theory and the acid digestion experiments. In computer simulation the accessibility is highly dependent on the percolation threshold concentration (pc), which is 31.17%. Similarly, the accessibility of starch is highly dependent on an apparent percolation threshold near 30% by volume or approximately 40% by weight of starch. At p < pc a small amount of starch is removed from the surfaces only, but at p > pc connected pathways existing throughout the bulk of the material facilitate large amounts of starch extraction. The sharpness of the transition at pc increases with the ratio of sample thickness to starch particle size. The results of this work have application to conduction and reacting systems where one component is dispersed in a matrix of the other. 相似文献
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Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution(DS) on properties of films.Corn starch was modified with acetyl and butyryl groups and films were prepared by blending acylated starch with low density polyethylene(LDPE).Systematic studies were done to observe the effect of acyl groups,DS and starch concentration on the properties and biodegradability of the blend films.It was observed that blend films containing 5% acetylated and butyrylated starches of high DS(2.5,1.7) maintained 75% and 83% of tensile strength of LDPE films.Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370 °C and 389 °C which were higher than the decomposition temperature of native starch film(349 °C).Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE.Water absorption capacity of high DS acetylated and butyrylated starch blend films(4.18% and 3.76%,respectively) was lower than that of native starch films(5%).This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement. 相似文献
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The effects of the compatibilizer polyethylene grafted with glycidyl methacrylate (PE‐g‐GMA) on the properties of low‐density polyethylene (LDPE) (virgin and reprocessed)/corn starch blends were studied. LDPE (virgin and reprocessed)/corn starch blends containing 30, 40 and 50 wt% starch, with or without compatibilizer, were prepared by extrusion and characterized by the melt flow index (MFI), tensile test, dynamic mechanical analysis (DMTA) and light microscopy. The addition of starch to LDPE reduced the MFI values, the tensile strength and the elongation at break, whereas the modulus increased. The decreases in the MFI and tensile properties were most evident when 40 and 50 wt% starch were added. Blends containing 3 wt% PE‐g‐GMA had higher tensile strength values and lower MFI values than blends without compatibilizer. Light microscopy showed that increasing the starch content resulted in a continuous phase of starch. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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P. MatzinosV. Tserki C. GianikourisE. Pavlidou C. Panayiotou 《European Polymer Journal》2002,38(9):1713-1720
Low-density polyethylene/plasticized starch/polycaprolactone blends were processed by conventional extrusion, injection molding, and film blowing techniques. The glass transition temperatures of plasticized starch were determined using differential scanning calorimetry. The blends were characterized by mechanical property measurements and scanning electron microscopy. The blend properties were found to depend not only on composition but also on the generated morphology. In films the fine dispersion of polycaprolactone phase in the polyethylene/starch matrix resulted in mechanical property increase, while in injection specimens there was property decrease due to phase coalescence. It appears that the different conditions existing at the two different shaping processes i.e. film blowing and injection molding could account for the final obtained morphology. 相似文献
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The use of degradable polymers for the collection and composting of organic wastes is explored within this paper. With reference to one trial where the performance of a ‘degradable’ polyethylene based sack for the kerbside collection of organic wastes was investigated. Areas for consideration were the impacts of the degradable polymer on the composting process and the quality of the finished product. This trial also included a comparative study of two different types of ‘degradable’ polymer sacks currently on the European market (polyethylene and starch). A number of quantitative tests were conducted on the different polymers to assess the mechanisms of degradation and how this affected their suitability for the treatment of organic wastes. Provisional results have indicated that the polyethylene (PE) sacks are not degrading as anticipated within open windrow conditions, adversely affecting both the composting process and the quality of the finished compost product. Whilst the degradable starch based sacks appear to actively degrade within open windrow compost conditions. 相似文献
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Polyvinyl pyrrolidone/polyethylene glycol hydrogels (PVP/PEG) and PVP/PEG/Starch were prepared by irradiating the mixtures of aqueous solutions of PVP, PEG and starch with electron beam at different doses. Their properties were evaluated to identify their usability in wound dressing applications. The physical properties of the prepared hydrogels, such as gel content, swelling, water content and degree of water evaporation with varying composition and irradiation dose were examined to evaluate the usefulness of the hydrogels for wound dressing. The gel content increases with increasing PVP concentration due to increased crosslink density, and decreases with increasing the PEG concentration. PEG seems to act not only as plasticizer but also to modify the gel properties as gelation% and maximum swelling. Mechanical experiments were conducted for both PVP/PEG and PVP/PEG/Starch. The adding of PEG and starch to PVP significantly improves elongation and tensile strength of prepared hydrogels, respectively. The crystallinity of both prepared hydrogels was investigated with varying their components, XRD studies indicated that the crystallinity in the gel was mainly due to PVP and mainly decreased with enhanced starch content. The prepared hydrogels had sufficient strength to be used as wound dressing and could be considered as a good barrier against microbes. 相似文献