Abstract

The main aim of this work was to study the effect of surface modification on the characteristics of local Pine cone flour (PCF) and on the interfacial adhesion in polypropylene/poly(lactic acid)/Pine cone (PP/PLA/PCF) blend composites. For this purpose, alkali, silane, and a combination of both treatments were applied to impart a hydrophobic character to the PCF flour. Treated and untreated flour samples were subjected to several investigations, such as Fourier transform infrared spectroscopy (FTIR), X-rays diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results revealed a reduction in the contents of hemicellulose, lignin, and wax upon treatments, as evidenced by the disappearance or reduction in the intensity of some characteristic bands, such as that related to the carbonyl groups (C = O) at 1730 cm⁻¹. Also, the treatments were seen to enhance the surface roughness, thermal stability, and crystallinity of the flour, as a result of greater exposure to cellulose. The dynamic mechanical analysis (DMA) showed that the storage modulus of blend composites with modified flour is higher than that of the unfilled blend. In this sense, the Alkali-GPTMS 5%-PCF composite exhibited a higher value by 20, 9, and 16% compared to Untreated-, Alkali-, and GPTMS-PCF composites, respectively. Surface treatments increased the interfacial adhesion, as it was perceived from the decrease in the height of tan δ peak owing to PP/PLA/PCF blend composites. Finally, the combination of both silane and alkali treatments was found to provide composites with a more cohesive microstructure owing to the improved compatibility.

摘要

这项工作的主要目的是研究表面改性对局部松果粉 (PCF) 特性和聚丙烯/聚乳酸/松果 (PP/PLA/PCF) 共混复合材料界面粘合力的影响。 . 为此目的，应用碱、硅烷和两种处理的组合以赋予 PCF 面粉疏水特性。对处理过和未处理过的面粉样品进行了多项研究，例如傅里叶变换红外光谱 (FTIR)、X 射线衍射 (XRD)、热重分析 (TGA) 和扫描电子显微镜 (SEM)。结果显示处理后半纤维素、木质素和蜡的含量降低，一些特征条带的消失或强度降低就是证明，^-1。此外，由于更多地暴露于纤维素，这些处理可以提高面粉的表面粗糙度、热稳定性和结晶度。动态力学分析（DMA）表明，改性面粉共混物的储能模量高于未填充共混物的储能模量。从这个意义上说，与未处理、碱和 GPTMS-PCF 复合材料相比，碱-GPTMS 5%-PCF 复合材料的值分别高出 20、9 和 16%。表面处理增加了界面附着力，这是由于 PP/PLA/PCF 共混复合材料导致的 tan δ 峰高度的降低。最后，由于相容性得到改善，发现硅烷和碱处理的组合可以为复合材料提供更具凝聚力的微观结构。