氢氧化钠催化淀粉/乳酸接枝共聚物的合成

以氢氧化钠(NaOH)为催化剂,采用原位一步法合成了淀粉/乳酸接枝共聚物。用红外光谱(IR)、扫描电镜(SEM)和核磁共振(1H-NMR)测试方法对淀粉/乳酸接枝共聚物的结构进行了表征。IR和1H-NMR核磁图谱均表明,聚乳酸确实接枝到了淀粉上;SEM分析表明,经乳酸接枝改性后的淀粉的形貌发生了很大变化。同时通过改变NaOH溶液浓度,原料比例,聚合温度和聚合时间考察了反应条件对淀粉与乳酸接枝率的影响,结果表明,当NaOH溶液浓度为0.4 mol/L,淀粉∶乳酸(质量比)为1∶6,聚合温度为90℃,聚合时间为9 h时,淀粉的接枝率可达33.6%。

Synthesis of Lactic Acid Grafting Starch Copolymer Catalyzed with Sodium Hydroxide

Starch/lactic acid grafting copolymer was prepared by in-situ graft copolymerization of starch and lactic acid catalyzed with sodium hydroxide(NaOH).The structure of starch/lactic acid copolymer was characterized by Fourier transform infrared spectrum(FT-IR),scanning electron microscope(SEM) and 1H nuclear magnetic resonance spectrum(1H-NMR).IR and 1H-NMR spectra indicate that polylactic acid is grafted onto the starch,and SEM analysis shows that the morphology of starch grafted by lactic acid changes greatly.The effect of NaOH concentration,mass ratio between starch and lactic acid(LA),reaction temperature and reaction time on the grafting degree was also investigated.It is found that the highest grafting degree can reach 33.60% when the graft copolymerization is carried in 0.40 mol/L NaOH aqueous solution for 9 h at 90 ℃ with the 1∶5-6 as the mass ratio between starch and lactic acid.