超臨界二氧化碳中天然橡膠的接枝改性研究-文庫吧資料
2025-07-03 15:59本頁面
【正文】 NR) has poor resistance to oils and unpolar solvents, poor tensile strength and hardness, but these properties of natural rubber can be improved by grafting of poly(methyl methacrylate). In this paper, we report research work on which the graft copolymer of natural rubber and poly(methyl methacrylate) (NRgMMA, with the trade name of Heaveaplus MG) was synthesised using the traditional solution polymerization and the supercritical carbon dioxide(SCCO2) dispersion polymerization respectively. The ungrafted NR and the graft copolymer NRgMMA were well characterized by Infrared test and Scanning Electron Microscope(SEM) analysis. The mechanical properties and oil resistance test of the products were carried out. It was found that the structure of NRgMMA was obviously different from NR, and the properties of NRgMMA were remarkably improved because of the existence of the polar poly(methyl methacrylate) on the natural rubber. These results confirmed that supercritical carbon dioxide may be a good green solvent for the graft modification of NR.Key words: natural rubber。(3) 對接枝前后的天然橡膠進行力學性能、耐油性的測試，結果表明，接枝天然橡膠的拉伸強度、硬度、耐油性都有了明顯的提高。 (a) 天然橡膠 (b) 溶液法合成的 (c) SCCO2法合成的NR NRgMMA NRgMMA圖 Ⅵ 接枝前后天然橡膠斷面的SEM照片3 結論(1) 采用溶液聚合法成功對天然橡膠進行了接枝改性，合成了NRgMMA，并通過IR測試證實了MMA的存在；同時嘗試用SCCO2分散聚合法對天然橡膠進行接枝改性，也成功合成了NRgMMA。這是因為接枝前天然橡膠大分子鏈是柔性的直鏈，組成大分子的原子不斷旋轉和振動，使分子鏈成卷縮狀態(tài)，因而由蜷曲的橡膠鏈組成的粒子形態(tài)有較大差異。由圖Ⅴ可見，接枝橡膠NRgMMA的增重率明顯低于天然橡膠，表明接枝后的天然橡膠其耐油性有了明顯改善，其原因是非極性的天然橡膠分子鏈上接枝上了極性的聚甲基丙烯酸甲酯側鏈，使橡膠的極性增強，根據“溶度參數相近相溶”原則，極性基團能夠對油（石油醚、汽油等）具有很好的抗耐性，并且極性基團濃度越大，耐油性越好，因而接枝橡膠(NRgMMA)的耐油性得到了改善。剛性增強，拉伸時產生的形變相對減小，因而接枝后的天然橡膠的斷裂伸長率較改性前有所下降。
研究報告相關推薦
鄂ICP備17016276號-1