Yilmaz Galip, Devahastin Apichart, Turng Lih-Sheng
Technical Scientific Vocational School, Bayburt University, Bayburt 69000, Turkey.
Wisconsin Institutes for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA.
Polymers (Basel). 2022 Mar 16;14(6):1193. doi: 10.3390/polym14061193.
Conventional solid injection molding (CIM) and microcellular injection molding (MIM) of a highly filled polycarbonate (PC) composite with glass fibers and carbon black were performed for molding ASTM tensile test bars and a box-shape part with variable wall thickness. A scanning electron microscope (SEM) was used to examine the microstructure at the fractured surface of the tensile test bar samples. The fine and uniform cellular structure suggests that the PC composite is a suitable material for foaming applications. Standard tensile tests showed that, while the ultimate strength and elongation at break were lower for the foamed test bars at 4.0-11.4% weight reduction, their specific Young's modulus was comparable to that of their solid counterparts. A melt flow and transition model was proposed to explain the unique, irregular "tiger-stripes" exhibited on the surface of solid test bars. Increasing the supercritical fluid (SCF) dosage and weight reduction of foamed samples resulted in swirl marks on the part surface, making the tiger-stripes less noticeable. Finally, it was found that an injection pressure reduction of 25.8% could be achieved with MIM for molding a complex box-shaped part in a consistent and reliable fashion.
对含有玻璃纤维和炭黑的高填充聚碳酸酯（PC）复合材料进行了传统注塑成型（CIM）和微孔注塑成型（MIM），以制造ASTM拉伸试验棒和具有可变壁厚的盒形部件。使用扫描电子显微镜（SEM）检查拉伸试验棒样品断裂表面的微观结构。精细且均匀的泡孔结构表明该PC复合材料是适合发泡应用的材料。标准拉伸试验表明，虽然减重4.0 - 11.4%的发泡试验棒的极限强度和断裂伸长率较低，但其比杨氏模量与实心对应物相当。提出了一个熔体流动和转变模型来解释实心试验棒表面出现的独特不规则“虎皮纹”。增加超临界流体（SCF）用量和发泡样品的减重会导致部件表面出现漩涡痕，使虎皮纹不太明显。最后发现，使用微孔注塑成型以一致且可靠的方式成型复杂盒形部件时，注射压力可降低25.8%。
