摘要
天然橡胶(NR)在贮存过程中发生轻微的分子交联,塑性初值、门尼粘度和凝胶含量增加,致使其加工性能降低,后续加工能耗增加。采用高速冷冻离心、蛋白酶及脂肪酶处理天然胶乳制备离心天然橡胶(CNR)、脱蛋白天然橡胶(DPNR)、脱脂肪-脱蛋白天然橡胶(P-DPNR),并分析其贮存过程中的交联密度、交联点数量、凝胶含量、分子量和塑性初值(P0)的变化。结果表明:在贮存过程中,随贮存时间的延长,NR、CNR、DPNR的交联密度、交联点数量、凝胶含量、分子量和塑性初值(P0)均呈现显著的增大趋势。而P-DPNR的交联密度、交联点数量、凝胶含量、分子量和塑性初值(P0)在加速贮存0~12 h时,略有增加,加速贮存12~48 h时,变化比较平缓。红外谱图分析表明NR、CNR、DPNR的1 740 cm-1长链脂肪酸特征峰随贮存时间的延长而略微减小,P-DPNR的长链脂肪酸特征峰减弱。综合分析表明天然橡胶贮存过程中,醛基和环氧基等官能基团、表面蛋白、结合蛋白及脂质均影响分子交联网络的形成,其中脂质对交联网络的形成影响较大。
The slight intermolecular crosslinking and the increase in Wallace plasticity, Mooney viscosity and gel content that occurred in natural rubber on prolonged storage leads to bad processing properties and increase energy consumption of rubber processing. The centrifuged natural rubber （CNR）, deproteinized natural rubber （DPNR） and lipid-free DPNR （P-DPNR） were prepared by high speed refrigerated centrifugation, treatment with alkaline proteinase and lipase. And the variation of crosslinking density, total number of crosslink-point, gel content, molecular weight and P0 were studied during storage. The results showed that the crosslinking density, total number of crosslink-point, gel content, molecular weight and P0 of NR, CNR, DPNR increased with the prolonging of the storage time, while the crosslinking density, total number of crosslink-point, gel content, molecular weight and P0 increased slightly during accelerated storage from 0-12 h and showed little change after storage for 12 h of P-DPNR. FFIR spectra of NR, CNR and DPNR showed the band at 1 740 cm^-1, corresponding to the characteristic band of fatty acid ester decreased with increasing storage time. On contrary, the intensity for characteristic bands of P-DPNR was decreased. The results demonstrated that the presence of aldehyde groups or epoxy groups, proteins and lipids contributed to the molecular cross-linking during the accelerated storage, while the lipids of rubber is responsible for the formation of crosslinking during storage.
出处
《热带作物学报》
CSCD
北大核心
2017年第5期939-944,共6页
Chinese Journal of Tropical Crops
基金
国家自然科学基金资助项目(No.51363006
51563006)
公益性行业(农业)科研专项经费项目(No.201403066)
海南省重大科技计划项目(No.ZDKJ2016020-02)
关键词
天然橡胶
贮存
凝胶含量
交联密度
交联网络
Natural rubber
storage
gel content
crosslinking density
crosslinking network
