Tsagdi Artemis, Drossos Ioannis, Georgiou Despoina, Exarhopoulos Stylianos, Karasiotas Georgios, Kallitsis Joannis K, Kalogianni Eleni P
Department of Chemistry, University of Patras, GR-26504 Patras, Greece.
Thrace Plastics Pack S.A., Member of Thrace Group Companies, GR-67100 Magiko Xanthi, Greece.
Polymers (Basel). 2021 Jan 18;13(2):288. doi: 10.3390/polym13020288.
A new approach to the creation of polypropylene (PP) based foaming materials was developed using food grade foaming agents that were coated on the PP pellets. More specifically, sodium bicarbonate and organic acids were used to coat PP pellets using either polyethyleneoxide (PEO) or lipid esters as coating stabilizers. In order to overcome the problem of the thermal decomposition of sodium bicarbonate at temperatures lower than the PP melting temperature, which makes the direct foaming during melt mixing impossible, the proposed methodology was proved quite efficient. Thus, new PP masterbatches were prepared, where the foaming agents were incorporated as coating at PP pellets at contents up to 10%, and initially used in Lab scale injection machines in order to find the best combination of materials that resulted in the production of foamed articles. Subsequently selected material combinations were tested in an industrial scale injection molding machine, where an optimization of the injection parameters was attempted. The outcome of this was the production of PP articles with significantly increased void fraction, up to 14%, decreased thermal conductivity, up to 20%, and various pore sizes as was observed via microscopic examination using SEM and CLSM.
开发了一种制备聚丙烯（PP）基发泡材料的新方法，该方法使用涂覆在PP颗粒上的食品级发泡剂。具体而言，使用碳酸氢钠和有机酸，以聚环氧乙烷（PEO）或脂质酯作为涂层稳定剂来涂覆PP颗粒。为了克服碳酸氢钠在低于PP熔融温度下发生热分解的问题（这使得在熔融混合过程中直接发泡无法实现），所提出的方法被证明是非常有效的。因此，制备了新的PP母粒，其中发泡剂以高达10%的含量作为涂层掺入PP颗粒中，并首先在实验室规模的注塑机中使用，以找到能生产发泡制品的最佳材料组合。随后，对选定的材料组合在工业规模的注塑机中进行测试，并尝试对注塑参数进行优化。结果是生产出了PP制品，其孔隙率显著提高，高达14%，热导率降低，高达20%，并且通过使用扫描电子显微镜（SEM）和共聚焦激光扫描显微镜（CLSM）的显微镜检查观察到具有各种孔径。
