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以柠檬酸和聚乙二醇6000为原料,对甲苯磺酸为催化剂,两步法合成超支化聚酯,作为纳米碳酸钙的改性剂。以提高聚酯的特性黏度[η]为目标,对反应条件进行优化,优化结果为反应温度160℃,催化剂用量为原料总质量的3.0%,第一阶段常压反应3h,减压1h,第二阶段常压和减压均为3h。减压反应压强均为0.6kPa。对优化条件下产物测定[η]和酸值,并进行了FT-IR、GPC、TGA和DSC测试。结果表明[η]较高,为37.6mL/g,羧基酯化率为58.7%,数均分子量Mn为37.1×103,重均分子量Mw为77.6×103,在269.1℃以下仅失重3.0%,熔融温度Tm为51.0℃,结晶温度Tc为22.6℃,玻璃化转变温度Tg为-21.8℃。超支化聚酯改性纳米碳酸钙对淀粉基生物降解塑料增强效果明显。
Using citric acid and polyethylene glycol 6000 as raw materials and p-toluenesulfonic acid as catalyst, the hyperbranched polyester is synthesized by a two-step method as a modifier of nano-calcium carbonate. The optimum reaction conditions were as follows: reaction temperature 160 ℃, catalyst dosage 3.0% of the total mass of raw materials, reaction pressure 3h in the first stage, decompression 1h, The second stage of atmospheric pressure and decompression are 3h. Decompression reaction pressure is 0.6kPa. The [η] and acid values of the products under the optimized conditions were determined and the FT-IR, GPC, TGA and DSC tests were carried out. The results showed that [η] was higher, 37.6mL / g, carboxyl esterification rate was 58.7%, number average molecular weight Mn was 37.1 × 103, weight average molecular weight Mw was 77.6 × 103, weight loss was only 3.0% below 269.1 ℃, The temperature Tm was 51.0 ° C, the crystallization temperature Tc was 22.6 ° C, and the glass transition temperature Tg was -21.8 ° C. Hyperbranched polyester modified nano-calcium carbonate has obvious effect on starch-based biodegradable plastics.