Research Initiation: Net - Shape Manufacture of PolyethyleneTeraphthalate Foam Parts

微孔泡沫是指直径约为10微米的闭孔塑料。最近，一种了不起的新型泡沫材料被生产出来，它是用二氧化碳来发泡一种被称为PET的物质。由此产生的泡沫具有高强度、刚度和韧性，并且可能为微孔泡沫在承载应用中的使用开辟道路。本研究的目标是通过确定聚合物必须加工的条件，合成一种新的制造工艺来生产微孔PET部件。发泡循环中的变形将被整合在一起，这样可以在保留脆弱微观结构的同时生产出三维零件。其基本思想是寻求一种将变形过程与细胞成核和聚合物结晶过程分离的加工策略。利用电子显微镜技术研究了二氧化碳在PET发泡过程中诱导结晶的独特作用。差热分析将用于确定结晶程度作为气体浓度的函数。过程功能需求之间的耦合程度将通过实验进行研究。最后，将合成一个非耦合过程，该过程将允许独立控制微观结构（平均细胞尺寸和密度），泡沫中的结晶度和部分几何形状。

Microcellular foam refers to plastics with closed cells on the order of 10 micrometer in diameter. A remarkable new foam material has recently been produced by using carbon dioxide to foam a physic known as PET. The resulting foam possesses high strength, stiffness, and toughness, and may open the way for use of microcellular foams in load-bearing applications. The goal of this research is to synthesize a novel manufacturing process to produce microcellular PET parts, by defining the conditions under which the polymer must be processed. Deformation in the foaming cycle will be integrated such that three dimensional parts may be produced while preserving the fragile microstructure. The basic idea is to seek a processing strategy that uncouples the deformation process from the cell nucleation and the polymer crystallization processes. The unique role of carbon dioxide in inducing crystallization in PET during the foaming process will be studied using the electron microscopy techniques. Differential Thermal Analysis will be used to determine the extent of crystallization as a function of gas concentration. The extent of coupling between the process functional requirements will be studied experimentally. Finally, an uncoupled process that will allow independent control of microstructure (average cell size and density), degree of crystallinity in the foam, and the part geometry, will be synthesized.