模內氣體反壓與動態模溫協同控制應用於PS超臨界微細發泡射出成型機械性質之研究

Mechanical Properties of PS Foams Made Through Microcellular Injection Molding via Control Mechanisms of Gas Counter Pressure and Dynamic Mold Temperature

吳聖俊 ； 徐丁盛 ； 陳夏宗 ； 簡仁德

《中華科技大學學報》 53期 (2012/10) Pp. 1-15

https://doi.org/10.7095/JCUST.201210.0001

摘要

在本研究中，我們發展出模內氣體反壓（GCP）與動態模溫協同控制系統，並將其應用於超臨界微細發泡射出成型製程中。同時針對三種控制機制（包括氣體反壓控制、模溫控制、氣體反壓與模溫協同控制）與不同製程參數所造成發泡高分子之凝固層厚度、氣泡尺寸、與氣泡形態，來探討其對機械性質之影響。除此之外，並對三種不同控制機制所發泡成型試片間之機械性質做一比較。實驗結果顯示，不同氣體反壓壓力、持壓時間、與模具溫度等成型條件所造成之不同凝固層厚度、氣泡尺寸、與氣泡形狀對試片之機械性質有顯著之影響。增加氣體反壓壓力、持壓時間以及降低模具溫度，其拉伸強度會增加。而個別單獨增加氣體反壓壓力、持壓時間、與模具溫度等成型條件則其衝擊強度會降低。但當氣體反壓與動態模溫協同控制時，由於其同時受到凝固層厚度、氣泡尺寸、與氣泡形狀之影響，造成衝擊強度與製程參數間並無明顯之關係。在我們所選取之實驗條件下，模具溫度60℃搭配適當之GCP控制系統成型條件下，可在較薄凝固層厚度、較小且均勻之氣泡尺寸、以及良好之表面品質下得到最佳拉伸強度與衝擊性能之成品。

關鍵字

超臨界微細發泡射出成型 ； 氣體反壓 ； 動態模溫 ； 機械性質 ； 氣泡尺寸 ； 凝固層厚度

並列摘要

In this study we developed a foaming control system using Gas Counter Pressure (GCP) combined with mold temperature control in the microcellular foaming (MuCell) process. The effects of the skin thickness, cell size, and cell morphology resulting from the three control mechanisms (including GCP control alone, mold temperature control alone, and GCP combined with mold temperature control) and process parameters on the mechanical properties of foamed polymer were investigate. In addition, the mechanical properties of foamed specimens molded from these three control mechanisms were also compared. It was found that skin thickness, cell size, and cell shape had significant influences on the mechanical properties of specimens depending on the molding conditions of gas counter pressure, holding time, and mold temperature. By increasing gas counter pressure, holding time, and decreasing the mold temperature, the tensile strength increased. In addition, by increasing gas counter pressure, holding time, and mold temperature alone, impact strength decreased. But, there were no clear relationships for processing parameters when GCP combined with dynamic mold temperature control was used because the effects of the skin thickness, cell size, and cell shape on the impact strength were unclear. Under experimental condition at mold temperature of 60oC combined with appropriate GCP control system, better tensile strength and impact performance were achieved and specimens with thin skin, small and uniform cell size as well as better surface quality were produced.

並列關鍵字

Microcellular injection molding ； Gas counter pressure ； Mold temperature control ； Mechanical property ； Cell size ； Skin thickness