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天然高分子作为一种资源,来源丰富且可再生利用,越来越引起广泛的关注。文章介绍了对天然高分子材料教学实践采取的一些改革措施,以纤维素、甲壳素及淀粉等天然高分子的结构与性质及其相互关系为主线展开教学内容,加深学生的高分子理论的基础知识,加强培养学生自学能力和创新理念。改革教学模式,在教学过程中提高学生的学习兴趣,加强教与学的互动,培养创新精神,以达到良好的教学目的。 相似文献
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廖嫣华 《纤维素科学与技术》2004,12(1):61-61
纤维素是一种生长和存在于绿色植物中的丰富的可再生的(年再生850亿吨)天然高分子材料,纤维素材料的开发利用在高分子科学的建立、发展和工业应用方面都起到了重要的作用。特别是在石油资源开始逐步枯竭的时期,纤维素资源有可能代替石油成为现代化学工业的基本原料之一。中国科学院广州化学研究所纤维素化学重点实验室黄勇研究员和王林格博士领导的研究小组长期以纤维素衍生物所形成的液晶相为主要对象开展基础和应用方面的研究。最近在国家杰出青年基金项目的支持下,该研究小组利用可聚合单体作为溶剂对纤维素衍生物胆甾型液晶相溶液中各织… 相似文献
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纤维素接枝反应的研究进展 总被引:2,自引:0,他引:2
纤维素是世界上最丰富的天然可再生资源。离子液体是一种新型的绿色溶剂,在纤维素的均相接枝研究中正起着越来越重要的作用。文章介绍了纤维素接枝反应尤其是均相接枝反应的研究进展。 相似文献
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纤维素是天然存在的最丰富的再生性高聚有机物质,每年自然界合成的纤维素大约有10^11~10^12地亿吨。纤维素作为一种丰富而古老的生物能源被广泛地应用于现代工业。采用物理的方法对纤维素进行特殊的处理,或者采用化学的手段,将纤维素分子链中的结合键打开,引入新的官能团,就可以改变纤维素固有的特性,形成另具其它功能性质的衍生物,如纤维素醚,这些经过改性的纤维素在食品和药品中得到广泛的应用。 相似文献
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<正>日前,中国粉碎技术领航者——浙江力普粉碎设备有限公司在精制棉制备纤维素粉碎加工技术领域再传捷报,研发的"一种精制棉粉碎成套生产线"获得国家专利(专利号:ZL.201320555760.X)。这是在精制棉粉碎设备领域取得的又一科技成果。纤维素是世界上最丰富的天然有机物。拓展以纤维素为主的天然资源的高附值利用是国家可再生资源发展战略需要,是全球经济、能源和新材料发展的热点领域之一。棉花的纤维素含量接近100%,为天然的最纯纤维素来源。以纤维素为 相似文献
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黄原胶与丙烯酰胺接枝共聚反应的研究 总被引:1,自引:0,他引:1
以过硫酸铵为引发剂,在氮气保护下,研究了黄原胶与丙烯酰胺的接枝共聚反应。考察了单体浓度、引发剂浓度、反应温度和反应时间等因素对接枝率及接枝效率的影响,探讨了过硫酸铵引发黄原胶接枝丙烯酰胺共聚反应的基本规律。采用红外光谱、X射线粉末衍射对接枝共聚物的结构进行研究,用热重分析法表征了产物的热性能,并初步探讨了接枝机理。结果表明,过硫酸铵能有效地引发黄原胶与丙烯酰胺的接枝共聚反应,并且接枝率和接枝效率随单体浓度、引发剂浓度、反应温度的变化出现极大值,随反应时间的延长不断上升,直至基本不变。 相似文献
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Methacrylic acid (MA) was graft polymerized onto starch using Ce4+ initiator in aqueous medium. The dependence of grafting on the reaction variables, such as monomer and initiator concentration and time and temperature, was studied in detail. Acid hydrolysis and infrared (IR) spectroscopy were used for the confirmation of graft copolymer formation. Further, a representative graft copolymer was characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The solubility/swellability and the gelatinization characteristics of the copolymers are also reported. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1399–1403, 1997 相似文献
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Polypropylene (PP) was grafted with acrylamide using benzoyl peroxide (BP) as an initiator by melt mixture. Effects of various parameters such as monomer and initiator concentration, reaction time, and reaction temperature on degree of grafting were studied. The graft copolymers were characterized by irradiation (IR), electron spectroscopy for chemical analysis (ESCA), wide-angle x- ray diffraction (WAXD), DSC, and contact angle studies. 相似文献
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以N,N’-亚甲基双丙烯酰胺(MBA)为单体,过硫酸钾为引发剂,研究了MBA与纤维素在离子液体中的接枝共聚反应。通过正交单因素实验,研究了反应时间、单体用量、反应温度、引发剂用量对接枝效果的影响。实验结果表明:当反应时间为2 h,单体与纤维素质量比为3∶1,反应温度为50℃,引发剂用量为0.05 g时,接枝效果最好。此条件下,MBA与纤维素的接枝率可达38.06%。 相似文献
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Meltem Çelik 《Journal of Polymer Research》2006,13(5):427-432
In this article, methacrylamide was successfully grafted onto starch using benzoyl peroxide as a radical initiator in aqueous
medium. The extent of grafting was found to be affected by the initiator, monomer, starch concentration, and temperature.
The optimum initiator concentration is 2.0×10−3 mol/L. The graft yield was observed to increase with the monomer concentration and temperature. No optimum values for the
monomer concentration and temperature were found. The overall activation energy for graft copolymerization was obtained. The
grafted starches were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray
diffraction (XRD), and scanning electron microscopy (SEM). TGA thermograms showed that the thermal stability of starch increased
as a result of grafting. SEM micrographs showed that the granular structure of starch was not maintained after graft copolymerization.
The water uptake and moisture retainment values of starch graft copolymers were investigated. 相似文献
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采用半连续种子乳液接枝聚合枝术,在聚丁二烯乳胶粒子上接枝共聚苯乙烯,合成了聚丁二烯接枝聚苯乙烯(PB-g-PS)接枝共聚物。研究了合成工艺条件对接枝共聚反应的影响,实验结果表明,苯乙烯在聚丁二烯橡胶粒子上的接枝效率和接枝度随聚丁二烯对苯乙烯质量比的增加而降低,随反应温度的增加而增加,随引发剂浓度的增加呈先增加后降低的变化趋势,接枝效率随单体滴加时间的增加而增加,接枝度则呈先增加后降低的变化趋势。利用FTIR和1H-NMR对PB-g-PS接枝共聚物进行了表征,证明合成了目的产物。利用TEM对PB-g-PS乳胶粒子进行了形态观察,接枝物为球形粒子,且具有核壳结构。 相似文献
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微波辐射下壳聚糖-丙烯酰胺接枝物的合成及其絮凝性能研究 总被引:1,自引:1,他引:1
以硝酸铈铵作为引发剂、丙烯酰胺为单体,用微波辐射法合成了壳聚糖-丙烯酰胺接枝共聚物。通过正交试验考察反应条件对接枝率和接枝效率的影响,得出最佳工艺条件为:反应时间12 min,引发剂浓度5 mmol/L,丙烯酰胺和壳聚糖质量比5:1,反应温度40℃。最佳条件下接枝率和接枝效率分别达到148.6%和44.0%。壳聚糖接枝物与聚丙烯酰胺(PAM)对高岭土悬浮液的絮凝对比试验表明:在酸性条件下接枝物与PAM的絮凝效果相近;在中性和碱性条件下接枝物的絮凝性能优于PAM。 相似文献
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A series of novel temperature- and pH- responsive water-soluble graft copolymers, casein-g-poly(N-isopropylacrylamide)(PNIPAAm),
were prepared via a direct graft copolymerization of N-Isopropylacrylamide (NIPAAm) from casein. The polymerization was induced
by tert-butyl hydroperoxide (TBHP) in water at general condition. Chemical structures of the graft copolymers were characterized
by Fourier transform infrared spectra (FTIR), Thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC).
The effect elements on graft copolymerization, such as concentration of initiator, reaction time, reaction temperature and
ratio of NIPAAm to casein were investigated in terms of NIPAAm conversion, grafting percentage (GP) and grafting efficiency
(GE), respectively. The graft copolymers are stimuli-sensitive with respect to both temperature and pH in aqueous solutions.
It could self-assembly into core-shell particles in aqueous solution with collapsed PNIPAAm as core as well as inverse core-hair
particles with expanded casein as core on changing temperature or pH, as indicated by transmission electron microscopy (TEM). 相似文献
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Synthesis and characterization of microcrystalline cellulose‐graft‐poly(methyl methacrylate) copolymers and their application as rubber reinforcements
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In this study, redox‐initiated free radical graft copolymerization of microcrystalline cellulose (MCC) and methyl methacrylate (MMA) has been carried out in aqueous media to develop a novel cellulose‐based copolymer. Cerium ammonium nitrate was used as the initiator in the presence of nitric acid. Effects of monomer concentration, initiator concentration, polymerization time, and polymerization temperature on the graft parameters of copolymers were studied. The successful grafting copolymerization between MCC and MMA was validated through attenuated total reflection, wide‐angle X‐ray diffraction, field‐emission scanning electron microscopy, and thermal gravimetric analysis. In comparison to native MCC, the resultant copolymers exhibited enhanced thermal stability and better compatibility with natural rubber, suggesting its potential application as reinforcement material in rubber industry. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42666. 相似文献