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PREPARATION OF NEW RUBBER MATERIALS FROM HIGHLY DEPROTEINIZED NATURAL RUBBER

高脱蛋白天然橡胶制备新型橡胶材料

基本信息

批准号：
07555594
负责人：
TANAKA Yasuyuki
金额：
$ 1.6万
依托单位：
TOKYO UNIVERSITY OF AGRICULTURE AND TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

Highly deproteinized natural rubber (HDPNR) latex was prepared by incubation of commercial high-anmonia latex with a proteolytic enzyme in the presence of a surfactant, followed by centrifugation twice. The nitrogen content of HDPNR was less than 0.02%, suggesting the complete removal of protein in the rubber.Low molecular-weight natural rubber (LNR) and LNR latex were prepared by oxidative degradation of HDPNR latex in the presence of 1 phr of K_2S_2O_8 and 15 phr of propanal, by shaking at 60ﾟC.The intrinsic viscosity [eta] of HDPNR with only K_2S_2O_8 decreased from 7.2 to 5.5 after 2 hr and then increased to 6.5 after 3 hr. By the additaion of propanal, HDPNR showed a significant decrease in[eta]to give 0.5 after 5 hr of the rection, while rubber from high-ammonia nataural rubber latex showed a slight decrease in[eta]. The concentration of latex and the kind of surfactant used for stabilizing latex gave no much effect on the degradation rate of HDPNR latex. The LNR latex is stable as latex form and the dried rubber coagulated from latex is transparent and colorless. The LNR was a telechelic polymer containging aldehyde and ketone groups at both terminals by NMR and molecular weight analyzes.A graft copolymer of natural rubber with stirene was made from HDPNR latex with tert-butyl hydroperoxide/tetra ethylene pentamine (TBHPO-TEPA) as an organic redox initiator, The stirene content, graft efficiency and molecular weight of grafted polystirene were significantly increased by deproteinization. The unber of grafting sites for graft copolymer from HDPNR latex was about three-times larger than that determined for graft copolymer from untreated natural rubber latex. The differences of reactivity between HDPNR and untreated natural rubber were explained to be due to the removal of protein and naturally occurring antioxidant present in untreated natural rubber.

通过在表面活性剂存在下将商业高氨胶乳与蛋白水解酶孵育，然后离心两次来制备高度脱蛋白天然橡胶（HDPNR）胶乳。在1份K_2S_2O_8和15份丙醛的存在下，将HDPNR胶乳氧化降解，制得低分子量天然橡胶（LNR）和LNR胶乳。K_2S_2O_8的加入使HDPNR的特性粘数[η]在2小时后由7.2下降到5.5，3小时后又上升到6.5。反应5小时后，HDPNR的[eta]显着降低至0.5，而高氨天然胶乳的橡胶的[eta]略有降低。胶乳浓度和稳定胶乳的表面活性剂种类对HDPNR胶乳的降解率影响不大。LNR胶乳以胶乳形式稳定，从胶乳中凝结的干燥橡胶透明无色。通过核磁共振和分子量分析，LNR是一种两端含醛、酮基团的遥爪聚合物，以叔丁基过氧化氢/四乙烯五胺（TBHPO-TEPA）为有机氧化还原引发剂，用HDPNR胶乳制备了天然橡胶与苯乙烯的接枝共聚物。HDPNR胶乳接枝共聚物的接枝位点数是未处理天然胶乳接枝共聚物的3倍。HDPNR和未处理的天然橡胶之间的反应性的差异被解释为是由于去除蛋白质和天然存在的抗氧化剂存在于未处理的天然橡胶。