针对传统木塑复合材料(wood plastic composites，WPCs)密度大、尺寸稳定性差等问题，以稻壳和聚氯乙烯(polyvinyl chloride，PVC)为原料制备三种密度的稻壳/聚氯乙烯发泡复合材料(rice husk/polyvinyl chloride foamed composites，RHPC)，分别标记为RHPC-Ⅰ、RHPC-Ⅱ、RHPC-Ⅲ，探究密度变化对RHPC性能的影响。结果显示:随着发泡程度的增加及密度的减小，RHPC的泡孔均匀程度有所降低。RHPC的线性热膨胀系数(coefficient of linear thermal expansion，CLTE)及吸水膨胀率均逐渐升高，且长度、宽度和厚度三个方向上的尺寸变化率均表现出各向异性;不同湿度和温度作用下的尺寸变化率表明湿度对RHPC尺寸的影响大于温度。RHPC-Ⅰ、RHPC-Ⅱ、RHPC-Ⅲ的弯曲强度、弯曲模量和抗蠕变性能呈下降趋势;RHPC-Ⅱ由于均匀的泡孔结构呈现出最高的冲击强度和比冲击强度，分别为14。3 kJ/m2 和19。9(kJ·m-2)/(g·cm-3)。本研究为轻质高强WPCs的开发和拓宽其应用领域提供指导。
Effect of Density on the Dimensional Stability and Mechanical Properties of Rice Husk/Polyvinyl Chloride Foamed Composite Materials
This study investigated the effect of density variations on the performance of rice husk/polyvinyl chloride(PVC)foamed composite materials(RHPC)to address the challenges of high density and poor dimensional stability in traditional un-foamed wood plastic composites(WPCs).Three distinct densities of RHPC were fabricated using rice husk and PVC.The results revealed that as the foaming degree increases,the density and the uniformity of the cell pores decrease respectively.Notably,the coefficient of linear thermal expansion(CLTE)and water absorption expansion rate of the RHPC progressively increased from RHPC-Ⅰ to RHPC-Ⅲ,exhibiting anisotropy in dimensional changes across length,width,and thickness directions.Further analysis indicated that humidity exerted a greater effect on the dimensional stability of RHPC than the temperature.Additionally,a decrement in the bending strength,bending modulus,and creep resistance was observed from RHPC-Ⅰ to RHPC-Ⅲ.However,RHPC-Ⅱ exhibited the highest impact strength of 14.3 kJ/m2 and specific impact strength of 19.9(kJ·m-2)/(g·cm-3),which was attributed to its uniform cell structure.This research provides valuable insights for developing lightweight-high-strength WPCs and expanding its potential applications.
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