淀粉/酚醛预聚物共缩聚胶黏剂的制备

以玉米淀粉为原料,采用次氯酸钠进行氧化改性,并以聚乙烯醇为接枝剂进行接枝改性,再与酚醛预聚物进行共缩聚反应,制得淀粉/酚醛预聚物(S/PFO)共缩聚胶黏剂。讨论了淀粉/酚醛预聚物比例、共缩聚温度和共缩聚时间对S/PFO共缩聚胶黏剂固体含量、黏度、固化时间、干状胶合强度和湿状胶合强度的影响。结果表明,淀粉/酚醛预聚物比例为15/120,共缩聚温度为90℃,共缩聚时间为2.0 h时,所制得的S/PFO共缩聚胶黏剂综合性能最佳。采用同步热分析和扫描电子显微镜对S/PFO共缩聚胶黏剂的固化性能和胶合界面进行了表征。相比于酚醛树脂胶黏剂,S/PFO共缩聚胶黏剂固化温度和固化焓值均降低,能够有效降低生产能耗。S/PFO共缩聚胶黏剂能将木材表面的孔隙均匀填满,形成一层薄薄的且连续的胶膜,有利于提高其胶接强度和耐水性能。

Preparation of Starch/Phenolic Prepolymer Copolycondensation Adhesive

Corn starch was oxidized with sodium hypochlorite and grafted with polyvinyl alcohol.And then the copolycondensation was carried out with the phenolic prepolymer to prepared starch/phenol-formaldehyde oligomers(S/PFO)copolycondensation adhesive.The effects of starch/phenol-formaldehyde oligomers ratio,copolymerization temperature and copolymerization time on the solid content,viscosity,curing time,dry bonding strength and wet bonding strength of S/PFO copolymerization adhesive were discussed.The results show that the S/PFO copolycondensation adhesive has the best comprehensive properties when the starch/phenol-formaldehyde oligomers ratio is 15/120,the copolymerization temperature is 90℃and the copolymerization time is 2.0 h.The curing properties and bonding interface of S/PFO copolycondensation adhesive were characterized by simultaneous thermal analysis and scanning electron microscopy.Compared with phenolic resin adhesive,the curing temperature and curing enthalpy of S/PFO copolycondensation adhesive are decreased,which could effectively reduce the production energy consumption.S/PFO copolycondensation adhesive fills the pores of wood surface evenly,forming a thin and continuous film,which is beneficial to improve the bonding strength and water resistance.