Jongpanya-Ngam Pasawat, Khankrua Rattikarn, Seadan Manus, Suttiruengwong Supakij
Department of Materials Science and Engineering, Faculty of Engineering and Industrial Technology, Silpakorn University, Nakhon Pathom, Thailand.
Department of Materials Engineering, Faculty of Engineering, Rajamangala University of Technology Rattanakosin, Nakhon Pathom, Thailand.
Des Monomers Polym. 2022 May 6;25(1):115-127. doi: 10.1080/15685551.2022.2072697. eCollection 2022.
The improvement of the crystallization of poly(lactic acid) (PLA) is one of the key areas to allow PLA to perform better at higher temperature and load bearing. Due to its slow crystallization rate, either organic or inorganic nucleating agents (NAs) can be used to improve the crystallization rate of PLA. In the case of organic NAs, aromatic sulfonate salt and bisamide compounds are promising ones because they can control better clarity. The aim of this work was to study the crystallization behavior of PLA using as-synthesized dimethyl 5-sulfoisophthalate sodium salt (SSIPA) as a nucleating agent in comparison with the commercial sulfonate salt (LAK-301). Two grades of PLA (PLA L105 and PLA 3251D) were used in this study. PLA samples were prepared by internal mixer and compression molding. All samples were investigated by DSC and POM. The results from DSC showed that after introducing the nucleating agents into PLA, the crystallinity in all samples was improved. The highest crystallinity at 57.48% was obtained from PLA L105/SSIPA1.0. Isothermal crystallization kinetics showed the improvement in overall crystallization rate of PLA with nucleating agents. The lowest half time crystallization obtained was 1.19 min for PLA L105/SSIPA1.0 at 135 °C. The results from POM indicated the substantial increase of the nucleus density and smaller spherulite size upon adding nucleating agents.
聚乳酸（PLA）结晶性能的改善是使PLA在更高温度和承载条件下表现更优的关键领域之一。由于其结晶速率缓慢，有机或无机成核剂（NAs）均可用于提高PLA的结晶速率。对于有机成核剂而言，芳族磺酸盐和双酰胺化合物是很有前景的，因为它们能更好地控制透明度。本工作的目的是研究以合成的5-磺基间苯二甲酸钠盐（SSIPA）作为成核剂时PLA的结晶行为，并与市售磺酸盐（LAK-301）进行比较。本研究使用了两种等级的PLA（PLA L105和PLA 3251D）。PLA样品通过密炼机和压缩模塑制备。所有样品均通过差示扫描量热法（DSC）和偏光显微镜（POM）进行研究。DSC结果表明，将成核剂引入PLA后，所有样品的结晶度均得到提高。PLA L105/SSIPA1.0的结晶度最高，达到57.48%。等温结晶动力学表明，添加成核剂后PLA的整体结晶速率有所提高。在135℃下，PLA L105/SSIPA1.0的最低半结晶时间为1.19分钟。POM结果表明，添加成核剂后，核密度显著增加，球晶尺寸减小。
