【作者】 郑丙利；

【导师】 陈金周； 李新法；

【作者基本信息】 郑州大学 ， 材料学， 2004， 硕士

【摘要】 本工作以玉米原淀粉为基料，以MMA为接枝单体，分别用γ-辐照引发和硝酸铈铵(CAN)及过硫酸钾(KPS)为引发剂，首次采用固相半干法新工艺合成了玉米淀粉—MMA的接枝共聚物。考察了反应介质(水、乙二醇、丙三醇)、反应气氛、辐照剂量、引发剂、反应时间、反应温度和单体／淀粉比例等因素对淀粉接枝MMA的接枝率G、接枝效率GE和单体转化率C等接枝参数的影响；利用红外光谱(IR)、X射线衍射(XRD)、偏光显微镜(PLM)和热分析(DSC、TG)等现代分析技术对所合成的淀粉—MMA接枝物的结构进行了研究。并对该接枝物的热塑化特性、力学性能和耐水性进行了初步研究。结果表明： 与传统的湿法工艺相比，固相半干法合成淀粉接枝共聚物具有：淀粉无需预糊化，引发剂用量相对较少，接枝率、接枝效率和单体转化率高，反应体系含水量较少和产品后处理工艺简单等特点。 在室温下的γ-射线共辐射淀粉—MMA接枝过程中，当辐射剂量在4～5kGy、水(或乙二醇)／淀粉配比在0.3～0.5左右时，接枝反应的接枝率G、接枝效率GE和单体转化率C均较高；真空条件有利于提高辐照淀粉-MMA接枝的G、GE和C，且单体中阻聚剂的去除与否对辐照淀粉-MMA接枝反应影响甚微。 采用半干法工艺，以CAN及KPS为引发剂进行淀粉—MMA接枝共聚时，淀粉无需糊化，反应过程中也无需通氮除氧。CAN为引发剂时，适宜的反应温度为40～50℃，适宜的反应时间为30min左右；KPS为引发剂时，适宜的反应温度为60～65℃，适宜的反应时间是40～50min；与湿法工艺相比，半干法工艺具有高效、节能和环保等优势。 适量的水或／和乙二醇对淀粉-MMA的γ-射线共辐照和CAN或KPS为引发剂的接枝共聚反应具有促进作用，而丙三醇对该接枝反应的促进作用甚微。 接枝共聚物的水解实验和红外光谱分析，证明了接枝支链PMMA与淀粉分子链之间是通过化学键连接的。淀粉接枝共聚物的XRD、PLM、DSC和TG的分析以及转矩流变实验，证明了淀粉的接枝共聚可以破坏淀粉的结晶结构，改善了淀粉的热塑化性能和热稳定性能。改性淀粉耐水性的实验表明，淀粉的接枝改性可以显著的提高淀粉材料的耐水性。更多还原

【Abstract】 In this work , using cornstarch as trunk polymer, and methyl methacrylate as grafting monomer, cornstarch-g-MMA(methyl methacrylate) copolymers were synthesized by semi-dry process with gamma irradiation , eerie ammonium nitrate(CAN) and potassium persulphate(KPS), respectively. The effect of reaction media such as water, glycol and glycerol etc., atmosphere, irradiation dose , initiators , reaction time , reaction temperature and monomer-to-starch ratio on the grafting parameters like grafting ratio(G), grafting efficiency(GE) and monomer conversion(C) was investigated .The structure of starch-g-MMA copolymers were characterized by means of infrared spectroscopy , X-ray diffraction, differential scanning calorimetry, thermogravimetry and polarized light microscopy. The thermoplasticity , mechanic properties and water resistance of copolymer were studied primarily. The main results were obtained as follow:In comparison with traditional wet process, semi-dry process have advantages of without gelatinization , lower consumption of initiator, higher grafting ratio , grafting efficiency and monomer conversion , lower moisture of reaction mixture and simple post treatment.With respect to graft polymerization of MMA onto cornstarch by simultaneous irradiation at room temperature, The higher grafting ratio ,grafting efficiency and monomer conversion were obtained at 4~5kGy of irradiation dose, and 0.3-0.5 of water/dried starch ratio or glycol/dried starch ratio. Graft polymerization conducted under vacuum was of advantage of higher grafting ratio, grafting efficiency and monomer conversion , meanwhile, it was proved that effect of elimination of inhibitor on graft polymerization was negligible.It was not need to purge oxygen by nitrogen and to gelatinize starch during graftpolymerization by semi dry process using eerie ammonium nitrate and potassium persulphate as initiators. The optimum condition of graft polymerization initiated by CAN was at 40~50 of reaction temperature and approx SOmin of reaction time. The optimum condition of graft polymerization initiated by KPS was 60-65 "C of reaction temperature and about 45min of reaction time. The semi dry process had some advantages such as high efficiency , low cost and without pollution over wet process .The graft polymerization initiated by gamma irradiation , CAN , and KPS could be effectively promoted when either certain water or glycol was added, but glycerol had little effect on graft polymerization.It was proved that the linkage of grafted PMMA and trunk polymer was chemical bonding by infrared spectra analysis and hydrolysis of modified starch. The crystal of starch was destructed and thermal stability , thermoplasticity of starch were improved because of grafting reaction , it was demonstrated not only by analysis of graft copolymers by XRD, TG ,DSC and PLM, but thermoplasticity of graft products improved. Water resistance of starch was improved markedly via garft polymerization , this result had been proved to determine water absorption of grafted starch soaked in water.更多还原