Tessanan Wasan, Phinyocheep Pranee, Amornsakchai Taweechai
Department of Chemistry, Faculty of Science, Mahidol University, Rama VI Road, Payathai, Bangkok 10400, Thailand.
Center of Sustainable Energy and Green Materials, Faculty of Science, Mahidol University, Phuttamonthon 4 Road, Salaya, Nakhon Pathom 73170, Thailand.
Polymers (Basel). 2023 Sep 20;15(18):3832. doi: 10.3390/polym15183832.
Starch extracted from pineapple stem waste underwent an environmentally friendly modification process characterized by low-energy consumption. This process resulted in the creation of dialdehyde pineapple stem starch featuring varying aldehyde contents ranging from 10% to 90%. Leveraging these dialdehyde starches, thermosetting plastics were meticulously developed by incorporating glycerol as a plasticizer. Concurrently, unmodified pineapple stem starch was employed as a control to produce thermoplastic material under identical conditions. The objective of streamlining the processing steps was pursued by adopting a direct hot compression molding technique. This enabled the transformation of starch powders into plastic sheets without the need for water-based gelatinization. Consequently, the dialdehyde starch-based thermosetting plastics exhibited exceptional mechanical properties, boasting a modulus within the range of 1862 MPa to 2000 MPa and a strength of 15 MPa to 42 MPa. Notably, their stretchability remained relatively modest, spanning from 0.8% to 2.4%. Comparatively, these properties significantly outperformed the thermoplastic counterpart derived from unmodified starch. Tailoring the mechanical performance of the thermosetting plastics was achieved by manipulating the glycerol content, ranging from 30% to 50%. Phase morphologies of the thermoset starch unveiled a uniformly distributed microstructure without any observable starch particles. This stood in contrast to the heterogeneous structure exhibited by the thermoplastic derived from unmodified starch. X-ray diffraction patterns indicated the absence of a crystalline structure within the thermosets, likely attributed to the establishment of a crosslinked structure. The resultant network formation in the thermosets directly correlated with enhanced water resistance. Remarkably, the thermosetting starch originating from pineapple stem starch demonstrated continued biodegradability following a soil burial test, albeit at a notably slower rate when compared to its thermoplastic counterpart. These findings hold the potential to pave the way for the utilization of starch-based products, thereby replacing non-biodegradable petroleum-based materials and contributing to the creation of more enduring and sustainable commodities.
从菠萝茎废料中提取的淀粉经历了一个以低能耗为特征的环保改性过程。这个过程产生了醛含量从10%到90%不等的二醛菠萝茎淀粉。利用这些二醛淀粉，通过加入甘油作为增塑剂精心研制出了热固性塑料。同时，使用未改性的菠萝茎淀粉作为对照，在相同条件下生产热塑性材料。通过采用直接热压成型技术来追求简化加工步骤的目标。这使得淀粉粉末无需水基糊化就能转化为塑料片。因此，基于二醛淀粉的热固性塑料表现出优异的机械性能，模量在1862兆帕至2000兆帕范围内，强度为15兆帕至42兆帕。值得注意的是，它们的拉伸性相对较小，在0.8%至2.4%之间。相比之下，这些性能明显优于由未改性淀粉制成的热塑性塑料。通过控制30%至50%的甘油含量来调整热固性塑料的机械性能。热固性淀粉的相形态显示出均匀分布的微观结构，没有任何可观察到的淀粉颗粒。这与未改性淀粉制成的热塑性塑料所呈现的异质结构形成对比。X射线衍射图谱表明热固性材料中不存在晶体结构，这可能归因于交联结构的形成。热固性材料中形成的最终网络与增强的耐水性直接相关。值得注意的是，源自菠萝茎淀粉的热固性淀粉在土壤掩埋试验后仍具有持续的生物降解性，尽管与热塑性对应物相比速度明显较慢。这些发现有可能为淀粉基产品的利用铺平道路，从而取代不可生物降解的石油基材料，并有助于创造更耐用和可持续的商品。
