红外光谱法测定杉木/聚丙烯复合材料中木粉和塑料含量

木塑复合材料(wood plastic composites, WPCs)中木材和塑料的配比影响其性能和价格，传统的热化学方法尚不能快速准确地测定WPCs中木塑配比。为探究红外光谱法定量分析WPCs中木粉和塑料的可行性，以杉木、聚丙烯(PP)以及各种添加剂为原料，经过木粉改性、混料和挤出造粒制备出13种不同杉木含量(9.8%～61.5%)的WPCs。采用KBr压片法对制得的样品进行红外光谱分析，通过对比WPCs、杉木、PP以及其他添加剂的红外谱图，确定杉木特征吸收峰为1 059，1 033和1 740 cm-1，1 377，2 839和841 cm-1表征PP特征峰。建立木粉含量、PP含量和二者特征吸收峰峰高比之间的相关关系，结果表明，木粉含量与I_{1 059}/I_{1 377}和I_{1 033}/I_{1 377}之间均存在极强的线性相关，R2分别为0.992和0.993，PP含量与I_{1 377}/I_{1 740}和I_{2 839}/I_{1 740}之间存在高度线性相关，R2分别为0.985和0.981，形成了杉木/PP复合材料中木粉和PP含量的红外光谱定量分析方法，木粉含量预测方程依次为y=53.297x-9.107和y=55.922x-10.238，PP含量预测方程依次为y=6.828 5x+5.403 6和y=8.719 7x+3.295 8。方法精密性和准确性检验表明，方法可重复性强、准确度高，木粉与塑料含量预测平均相对误差约为5%，与传统热化学方法相比，预测精度有较大提高，更重要的是红外光谱法操作更为简便。该研究为杉木/PP复合材料中木粉及塑料含量的测定提供了一种简便、快速、准确的方法。

Quantification of Wood Flour and Polypropylene in Chinese Fir/Polypropylene Composites by FTIR

The ratio of wood and plastic in Wood Plastic Composites (WPCss) influences quality and price, but traditional thermochemical methods cannot rapidly and accurately quantify the ratio of wood/PP in WPCss. This paper was addressed to investigate the feasibility of quantifying the wood flour content and plastic content in WPCss by Fourier Transform Infrared (FTIR) spectroscopy. With Chinese fir, polypropylene (PP) and other additives as raw materials, 13 WPCs samples with different wood flour contents, ranging from 9.8% to 61.5%, were prepared by modifying wood flour, mixing materials and extrusion pelletizing. The samples were analyzed by FTIR with the KBr pellets technique. The absorption peaks of WPCss at 1059, 1 033 and 1 740 cm-1 are considered as characteristic of Chinese fir, and the absorption peaks at 1 377, 2 839 and 841 cm-1 are typical of PP by comparing the spectra of WPCss with that of Chinese fir, PP and other additives. The relationship between the wood flour content, PP content in WPCss and their characteristic IR peaks height ratio was established. The results show that there is a strong linear correlation between the wood flour content in WPCss and I_{1 059}/I_{1 377}, I_{1 033}/I_{1 377}, R2 are 0.992 and 0.993 respectively; there is a high linear correlation between the PP content in WPCss and I_{1 377}/I_{1 740}, I_{2 839}/I_{1 740} R2 are 0.985 and 0.981, respectively. Quantitative methods of the wood flour content and PP content in WPCss by FTIR were developed, the predictive equations of the wood flour content in WPCss are y=53.297x-9.107 and y=55.922x-10.238, the predictive equations of the PP content in WPCss are y=6.828 5x+5.403 6 and y=8.719 7x+3.295 8. The results of the accuracy test and precision test show that the method has strong repeatability and high accuracy. The average prediction relative deviations of the wood flour content and PP content in WPCss are about 5%. The prediction accuracy has been improved remarkably, compared to thermochemical methods. More importantly, FTIR is more easy-handing. This experiment may provide a simple, rapid and accurate method for quantification of wood flour and PP in Chinese fir/PP composites.