Abstract:

In this paper, the grafting modification of natural rubber latex with ethyl acrylate(EA)/ allyl chloride(AC) as monomer was performed by supercritical carbon dioxide (scCO₂) swelling polymerization, and the graft copolymer NR-g-(EA/AC) was synthesized.The effects of reaction pressure and dosage of initiator on the monomer graft level and monomer conversion in the grafting copolymerization reaction were studied.The FT-IR spectra, mechanical properties, hardness, solvent resistance and fire resistance of NR-g-(EA/AC) were tested, and the graft level and conversion level of monomer were calculated, which were all compared with the values obtained from solution polymerization.It was found that the structure of grafted rubber changed significantly (the functional groups of C=O and —Cl were introduced) and the tensile strength, modulus of elasticity, hardness, solvent resistance and fire resistance of graft copolymers were improved greatly.The graft level and conversion level obtained from solution polymerization and supercritical carbon dioxide swelling polymerization were both high and the prepared products had similar mechanical properties, but the solvent resistance of the product obtained from solution polymerization was better than that obtained from supercritical carbon dioxide swelling polymerization.Due to the green solvent nature of supercritical carbon dioxide, supercritical carbon dioxide swelling polymerization would hopefully become a new green method for the grafting modification of natural rubber.

Key words:

天然胶乳, 接枝改性, 超临界二氧化碳溶胀聚合, 溶液聚合

摘要：

采用超临界二氧化碳溶胀聚合法，以丙烯酸乙酯（EA）/3-氯丙烯（AC）为单体对天然橡胶进行了接枝改性，合成了接枝共聚物NR-g-(EA/AC)。考察了压力和引发剂用量对接枝聚合反应的影响;对NR-g-( EA/AC)进行了红外光谱、力学性能、耐溶剂性、耐燃性、硬度的测试及接枝效率和接枝率的计算，并与溶液聚合法所得NR-g-( EA/AC)的性能进行了比较。结果发现，在接枝橡胶中成功的引入了—C=O和—Cl基团;接枝橡胶的弹性模量、拉伸强度、硬度、耐燃性和耐溶剂性较天然橡胶的有了显著提高。使用溶液法和超临界二氧化碳溶胀聚合法改性天然胶乳都获得了较高的转化率和接枝率，所得产品的机械力学性能相近，但溶液法所得产品的耐溶剂性能优于后一种方法。由于超临界二氧化碳的绿色溶剂性质，超临界二氧化碳溶胀聚合法有望取代溶液聚合法而发展成一种绿色的接枝改性天然橡胶方法。

关键词:

天然胶乳, 接枝改性, 超临界二氧化碳溶胀聚合, 溶液聚合