【作者】 王辉；

【导师】 顾正彪；

【作者基本信息】 江南大学 ， 制糖工程， 2011， 硕士

【摘要】 论文针对传统的淀粉胶粘剂因粘接强度小、贮藏稳定性差不能满足淀粉胶粘剂市场化的难题,研究了接枝参数、共聚单体、助剂等对淀粉胶粘剂粘接强度和贮藏稳定性的影响,并对淀粉胶粘剂的工艺进行最终的优化和确定,制备出粘接强度和贮藏稳定性都较好的新型淀粉基木材胶粘剂。首先,对蜡质玉米淀粉基木材胶粘剂的制备工艺条件进行优化,以接枝参数为指标选择较优的制备工艺条件,优化后的接枝共聚条件为:过硫酸铵(以下简称APS)的添加量为淀粉干基的1.16%(w/w)、接枝温度70℃、pH为5、接枝共聚时间3 h、滴加速度380.88 mL /(kg?h)、单体与淀粉的质量比6∶5、热处理条件85℃保温30min,此条件下制备的共聚物接枝百分率达到50.83%;并分析了接枝参数与淀粉胶粘剂压缩剪切强度之间的关系,发现接枝百分率和支链分子量均对淀粉胶粘剂的压缩剪切强度有影响,且接枝百分率对胶粘剂压缩剪切强度的影响比支链分子量的影响要大。其次,研究了接枝共聚改性对胶粘剂性能的影响。通过实验发现,采用丙烯酸丁酯为共聚单体对胶粘剂的粘接性能有比较大的提高,且分开滴加比共混滴加的效果要好,采用叔碳酸乙烯酯为共聚单体对胶粘剂的贮藏稳定性有一定的提升,且共混滴加的效果比分开滴加的效果要好。最后,本实验选取丙烯酸丁酯和叔碳酸乙烯酯两种共聚单体来改性,在丙烯酸丁酯的添加量为单体总量的7.5%、叔碳酸乙烯酯的添加量为单体总量的12.5%时,胶粘剂的综合性能较优。再则,对胶粘剂中的助剂进行了选择和优化。乳化剂十二烷基硫酸钠、稀释剂尿素、氧化剂过硫酸铵对胶粘剂的贮藏稳定性有一定的影响。通过正交实验发现三种助剂对胶粘剂贮藏稳定性都呈正面影响,且对贮藏稳定性的影响顺序为:十二烷基硫酸钠>尿素>过硫酸铵;而对胶粘剂的粘结强度影响中,只有尿素对胶粘剂呈现正面影响。最后,根据胶粘剂的情况选择三种助剂的量分别为:十二烷基硫酸钠为淀粉干基的2.28%,尿素为淀粉干基的22.86%,过硫酸铵为淀粉干基的2.86‰。最后对胶粘剂的失稳机理进行了探讨,氢键作用力是引起胶粘剂失稳的主要原因。最后,对在较优工艺下制备的淀粉胶粘剂的各项性能进行分析,并与白乳胶的行业标准进行比较,优化后的淀粉基木材胶粘剂能够达到白乳胶Ⅱ型的标准要求。更多还原

【Abstract】 The research of developing environmental high-performance wood adhesive by utilizing low-cost starch resources is one of the hot research fields.Since the poor shear strength and storage stability of traditional starch adhesive didn’t meet requirments of the starch adhesive market, we should choose the optimum process conditions and suitable copolymerization monomers to prepare a new kind of starch-based wood adhesive with high-shear strength and good-storage stability.Firstly,we chose the optimum process conditions to prepare the starch-based wood adhesive by the index of grafting parameters. After the optimization, the best grafting copolymerization conditions were: an APS quantity of 1.16% of dry starch weight、a reacting temperature of 70℃、an reacting pH of 5、an reacting time of 3h、a monomer’s adding rate of 380.88 mL (/kg?h)、a mass radio between monomer with starch of 6:5 and the heat treat conditions of 85℃30min,the graft radio of the starch-based wood adhesive prepared under the conditions is largest up to 50.83%.After analysing the relatioanship between grafting parameters with shear strength,we found the percent grafting and the average molecular weight of branched chain both had an good effect on the bonding strength,besides the percent grafting had a greater effect on the bonding strength than the average molecular weight of branched chain’s.Secondly,the effect of grafting coplymerization on the properties of the prepared adhesive was studied.The experimental results showed when the comonomer was BA, the shear strength of the adhesive was improved,and separate dropping had a better effect than blending droping.When the comonomer was Veova10,the storage stability of the adhesive was improved ,and blending dropping had a better effect than separate dropping.Finally,BA and Veova10 were both used to modify the adhesive ,and the modified adhesive’s properties were best when the BA monomer’s additive amount was 7.5% of total monomers’amount and the Veova10 monomer’s additive amount was 12.5% of total monomers’amount.Thirdly,the assistants of the adhesive were chose and optimized.The emulsifer of SDS、the diluent of urea、the oxidant of APS all had some effect on the storage stability of adhesive.The orthogonal experimental results showed three assistants all had a good effect on the storage stability of adhesive,and the sequence was SDS>urea>APS;among the three assistants ,only urea had a good influent on the shear strength.Finally,according to the situations of adhesive, three assiatants’adding amounts were as follows:SDS was 2.28% (w/w, base on the dry starch weight),urea was 22.86%(w/w, base on the dry starch weight),APS was 2.86‰(w/w, base on the dry starch weight).Finally, the instability mechanism of adhesive is discussed.Hydrogen bonding force is the main factor of adhesives’instability.At last,the properties of starch-based wood adhesive prepared at optimal conditions we analyzed.Properties of starch-based wood adhesive were compared with industry standard of polyvinyl acetate wood adhesives.更多还原