超声辅助提取对竹纤维结构和机械性能的影响

文章以超声波辅助提取竹纤维，研究超声波处理以及超声波处理方式（前超声和后超声）对低试剂量条件下提取竹纤维结构和热性能的影响。结果表明：超声波处理应用于低试剂量竹纤维提取，可降低竹纤维胶质含量，改善竹纤维细度和细度均匀性。用后超声辅助提取竹纤维，竹纤维胶质含量可降低13.2%，纤维直径由489±247 μm降至224±52 μm，平均直径降低率达54.2%。超声辅助提取对竹纤维机械性能有一定程度的影响，对竹纤维拉伸强度略有降低，拉伸模量下降明显，断裂伸长率略有提高，机械强度均匀性增加；后超声辅助提取较前超声辅助提取对竹纤维的机械性能降低程度小。经提取工艺，竹纤维结晶度增加，但超声辅助提取竹纤维结晶度又略有下降，未超声竹纤维结晶度为56.50%，后超声竹纤维结晶度为55.89%，前超声竹纤维结晶度为56.25%；傅里叶红外光谱分析表明，竹纤维化学结构变化主要由纤维提取工艺引起，超声处理对纤维结构影响不明显；通过电镜观察，经纤维提取工艺，原竹材结构中被胶质包覆的单纤维形态暴露，单丝状明显，超声辅助提取增加了纤维表面粗糙度，后超声辅助提取单丝分散性增强；总体上，超声辅助提取可促进低试剂量条件下的长竹纤维提取，对纤维细度有明显改善效果，但对纤维结构和机械性能影响不大。

The Influence of Ultrasonic-assisted Extraction on Bamboo Fiber Structure and Mechanical Properties

Ultrasonic-assisted extraction of bamboo fiber has been carried out to study the effect of ultrasonic treatment and its ways (pre-ultrasonic and post-ultrasonic treatments) on the structural and thermal performance of bamboo fibers extracted under low chemistry usage condition in this paper. The results indicate the application of ultrasonic treatment for bamboo fiber extraction in low chemistry usage condition can reduce the content of bamboo fiber's gum and improve the fineness and evenness of bamboo fibers. With the post-ultrasonic assisted extraction, the bamboo fibers' gun content can be reduced by 13.2%, and the fiber diameter can be reduced from 489±247 μm to 224±52 μm, with the average diameter decrease rate at 54.2%. Ultrasonic-assisted extraction has a certain degree of influence on the mechanical performance of bamboo fiber, which will slightly reduce the tensile strength, significantly decrease the tensile modulus, slightly improve the elongation rate at break and increase the uniformity of mechanical strength. The mechanical performance of bamboo fiber extracted by post-ultrasonic treatment has lower degree of reduction than that of pre-ultrasonic treatment. After the extraction process, the crystallinity of bamboo fibers increases, while that of bamboo fiber extracted by ultrasonic-assisted decreases slightly. The crystallinity of untreated bamboo fiber is 56.50%, and those of post-ultrasonic and pre-ultrasonic treatments are 55.89% and 56.25% respectively. The FITR shows that the ultrasonic treatment has no obvious effect on the bamboo fiber's chemical structure, and the change is mainly caused by the fiber extraction process. The SEM shows that the single fibers initially coated by gum in bamboo structure are exposed with monofilament after the ultrasonic treatment process. Ultrasonic-assisted extraction improves the fiber surface roughness, and post-ultrasonic-assisted extraction enhances the single fiber' dispersion. Overall, the ultrasonic-assisted extraction can improve the long fiber extraction in the low chemistry condition and also have an obvious improving effect on the fiber fineness, but have little influence on the structural and mechanical performance of bamboo fibers.