PLA-g-GMA的制备及其对PBAT/PLA共混物结晶性能的影响

Preparation of PLA-g-GMA and its effect on crystallization properties of PBAT/PLA blends

摘要:

采用转矩流变仪制备的聚乳酸-甲基丙烯酸缩水甘油酯接枝物（PLA-g-GMA）作为聚(对苯二甲酸/己二酸丁二酯)（PBAT）与聚乳酸（PLA）共混材料的相容剂，采用FTIR、1HNMR对PLA与GMA不同配比下PLA-g-GMA的接枝率进行分析，并通过DSC、SEM研究添加不同含量相容剂对PBAT/PLA共混物结晶以及微观形貌的影响。结果表明：GMA成功接枝到PLA上，当GMA添加量为总质量20%时，PLA-g-GMA有效接枝率达到6.44%；相容剂的加入使得共混物中PLA在降温过程中形成的结晶结构更加完善，当相容剂添加量为总质量6%时冷结晶峰消失；当相容剂质量分数4%时，PBAT/PLA共混物结晶温度由未添加相容剂时的75.4 ℃下降至68.0 ℃；PLA-g-GMA的加入使得共混物在结晶初期速率常数由0.83（未添加相容剂）下降至0.68（相容剂质量分数10%），抑制了初期PLA晶核产生，但促使第二阶段结晶速率由1.28（未添加相容剂）提高到1.38（相容剂质量分数2%），促进了PBAT晶体生长；相容剂使得脆断截面中PLA与PBAT之间剥离程度减小；当相容剂质量分数为8%时，PBAT/PLA共混纤维强度由未添加PLA-g-GMA时的0.25 cN/dtex提高至0.33 cN/dtex。

Abstract:

Polylactic acid-graft-glycidyl methacrylate (PLA-g-GMA) was prepared by torque rheometer as the compatibilizer of PBAT and PLA blends. The grafting rate of PLA-g-GMA at different proportions of PLA and GMA were analyzed by FTIR and 1H-NMR. The effects of the compatibilizer on crystallization and microstructure of PBAT/PLA blends were studied by DSC and SEM. The results showed that GMA was successfully grafted onto PLA. When the amount of GMA was 20% of the total mass, the grafting rate of PLA-g-GMA reached 6.44%. The addition of compatibilizer improved the crystallization structure of PLA in the blends during cooling, and the cold crystallization peak disappeared when the addition amount was 6% of the total mass. When the mass fraction of the compatibilizer was 4%, the crystallization temperature of PBAT/PLA blends decreased from 75.4 ℃(without compatibilizer) to 68.0 ℃. The addition of PLA-g-GMA reduced the initial crystallization rate constant of the blends from 0.83(without compatibilizer) to 0.68(when the mass fraction of compatibilizer was 10%), inhibited PLA from forming crystal nucleus. But it increased the second stage crystallization rate constant from 1.28(without compatibilizer) to 1.38(when the mass fraction of compatibilizer was 2%), which promoted the growth of PBAT crystals; The compatibilizer reduced the degree of detachment between PLA and PBAT in the brittle fracture section. When the mass fraction of compatibilizer was 8%, the strength of the PBAT/PLA blend fiber increased from 0.25 cN/dtex to 0.33 cN/dtex.