El-Taweel Safaa H
Chemistry Department, Faculty of Science, Cairo University, Orman-Giza, 12613, Egypt.
Engineering and Materials Science Department, German University in Cairo, New Cairo City, Egypt.
Sci Rep. 2024 Aug 5;14(1):18142. doi: 10.1038/s41598-024-68023-4.
The impact of adding ethylene vinyl acetate copolymer (EVA 80) and 1 wt% TiO nanoparticles on the morphology and crystallization behavior of poly(lactic acid) blends was investigated using DSC, SEM, and POM. Thermal analysis revealed the enhancement of crystallinity of PLA in the presence of TiO and higher EVA 80 content in the blend. The PLA and EVA 80 components showed compatibility, as evidenced by the shift of the glass transition temperatures of the PLA phase in the blend to lower values compared to neat PLA. The lower temperature shift of the cold crystallization of the PLA and the formation of the small spherulites of the PLA in the blends indicated that the EVA 80 and TiO act as a nucleating agent for crystallization. The non-isothermal crystallization parameters of the composites were evaluated using Avrami's modified model, the MO approach, and Friedman's isoconversional method. The Avrami's modified rate constant (K) and the effective activation energy values significantly increased with the incorporation of EVA 80 and TiO nanoparticles. Furthermore, the thermogravimetric analysis (TGA) showed improved thermal stability of PLA by adding EVA 80 and TiO.
采用差示扫描量热法（DSC）、扫描电子显微镜（SEM）和偏光显微镜（POM）研究了添加乙烯-醋酸乙烯酯共聚物（EVA 80）和1 wt%二氧化钛纳米颗粒对聚乳酸共混物形态和结晶行为的影响。热分析表明，在二氧化钛存在且共混物中EVA 80含量较高的情况下，聚乳酸的结晶度有所提高。聚乳酸和EVA 80组分表现出相容性，这可通过共混物中聚乳酸相的玻璃化转变温度向较低值移动得到证明，相比纯聚乳酸而言。聚乳酸冷结晶的较低温度偏移以及共混物中聚乳酸小球晶的形成表明，EVA 80和二氧化钛可作为结晶的成核剂。使用阿弗拉米修正模型、MO方法和弗里德曼等转化率方法评估了复合材料的非等温结晶参数。随着EVA 80和二氧化钛纳米颗粒的加入，阿弗拉米修正速率常数（K）和有效活化能值显著增加。此外，热重分析（TGA）表明，添加EVA 80和二氧化钛可提高聚乳酸的热稳定性。
