Murariu Marius, Paint Yoann, Murariu Oltea, Laoutid Fouad, Dubois Philippe
Laboratory of Polymeric and Composite Materials, Materia Nova Materials R&D Center & UMons Innovation Center, 7000 Mons, Belgium.
Laboratory of Polymeric and Composite Materials, Center of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons (UMons), 7000 Mons, Belgium.
Polymers (Basel). 2022 Jun 10;14(12):2360. doi: 10.3390/polym14122360.
The melt-mixing of polylactide (PLA) with micro- and/or nanofillers is a key method used to obtain specific end-use characteristics and improvements of properties. So-called "insoluble" CaSO (CS) β-anhydrite II (AII) is a mineral filler recently considered for the industry of polymer composites. First, the study proves that AII made from natural gypsum by a specifically thermal treatment is highly stable compared to other CS forms. Then, PLAs of different isomer purity and molecular weights (for injection molding (IM) and extrusion), have been used to produce "green" composites filled with 20-40 wt.% AII. The composites show good thermal and mechanical properties, accounting for the excellent filler dispersion and stability. The stiffness of composites increases with the amount of filler, whereas their tensile strength is found to be dependent on PLA molecular weights. Interestingly, the impact resistance is improved by adding 20% AII into all investigated PLAs. Due to advanced kinetics of crystallization ascribed to the effects of AII and use of a PLA grade of high L-lactic acid isomer purity, the composites show after IM an impressive degree of crystallinity (DC), i.e., as high as 50%, while their Vicat softening temperature is remarkably increased to 160 °C, which are thermal properties of great interest for applications requiring elevated rigidity and heat resistance.
聚乳酸（PLA）与微米级和/或纳米级填料的熔融共混是一种用于获得特定最终用途特性和性能改善的关键方法。所谓的“不溶性”硫酸钙（CS）β-硬石膏II（AII）是一种最近在聚合物复合材料行业中被考虑使用的矿物填料。首先，该研究证明，通过特定热处理由天然石膏制成的AII与其他CS形式相比具有高度稳定性。然后，使用不同异构体纯度和分子量的PLA（用于注塑成型（IM）和挤出）来生产填充有20-40 wt.% AII的“绿色”复合材料。这些复合材料表现出良好的热性能和机械性能，这归因于优异的填料分散性和稳定性。复合材料的刚度随着填料用量的增加而增加，而其拉伸强度则取决于PLA的分子量。有趣的是，在所有研究的PLA中添加20%的AII可提高抗冲击性。由于AII的作用导致结晶动力学先进，并且使用了高L-乳酸异构体纯度的PLA等级，复合材料在注塑成型后显示出令人印象深刻的结晶度（DC），即高达50%，同时其维卡软化温度显著提高到160°C，这些热性能对于需要高刚性和耐热性的应用非常重要。
