聚乙烯醇/纳米羟基磷灰石复合材料微型注塑研究

Microinjection molding of Poly ( vinyl alcohol )/ nano-hydroxyapatite composites

结合固相剪切碾磨和分子复合技术制备了适合于微型注塑加工的聚乙烯醇/纳米羟基磷灰石(PVA/n-HA)复合材料,实现了n-HA含量达30%的PVA/n-HA复合材料的微型注塑加工。采用差示扫描量热法(DSC)、热重分析仪(TGA)和高压毛细管流变仪研究了PVA/n-HA复合材料的热性能和流变性能,结果表明:改性PVA/n-HA复合材料的熔点降低,热分解温度升高,获得120℃以上的热塑加工窗口;PVA/n-HA复合材料呈现剪切变稀特性,在高剪切速率下具有较低的熔体粘度,适合微型注塑加工,具有良好的充模性能。采用扫描电子显微镜(SEM)和X射线衍射(XRD)研究了PVA/n-HA微型注塑样品的结构与性能,结果表明n-HA均匀分散于PVA基体中,提高了复合材料的尺寸稳定性;受微型注塑过程中高剪切应力诱导结晶作用的影响,PVA/n-HA微型注塑样品的结晶度高于常规注塑样品的结晶度。

PVA/n-HA composites suiting for microinjection molding were prepared based on Solid State Shear Milling （S：~M） and molecular complexation technologies, And the mieroin^ection molding of PVA/n HA composites with n-HA content of 30%0 were realized. The thermal properties, rheologieal properties of PVA/n-HA composites were characterized by differential scanning calorimetry （DSC）, thermogravimetric analysis （TGA） and high pressure capillary rheometer. The results showed that the melt point of modified PVA/n-HA composites decreased and the thermal decomposition temperature increased, obtaining the thermal processing window of more than 120~C. PVA/n-HA composites showed shear-thinning behavior and the low melt viscosity at high shear rate was suitable for microinjection molding. So PVA/n-HA composites had good mold filling performance. The structure and properties of PVA/n-HA mieroin}ection molded samples were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results showed that n-HA was well dispersed in PVA matrix and increased the dimension stability of the injection samples. Due to the effect of high shear force inducing crystallization of PVA in microinjection molding, the crystallinity of PVA/n-HA microinjection molded sample was higher than that of conventional injection molded sample.