慈竹不同尺度单元对复合板材物理力学性能的影响

Effect of Bamboo Units with Different Scales on the Physical and Mechanical Properties of Bamboo-based Panel

开发高强度竹基复合材料,拓展其在建筑工程领域的应用,是“竹材建材化”理念的有效实现途径。笔者将慈竹加工成竹篾片、竹束和维管束纤维3种不同尺度的单元材料,按不同组合方式组坯压制4种板坯结构的慈竹复合板材,并对其物理力学性能和端面形貌结构进行研究分析。研究结果表明:4种慈竹复合板材的吸水厚度膨胀率、抗弯性能和抗拉性能均处于GB/T 40247—2021《重组竹》标准规定的中上等级,其中竹篾片复合板材的物理力学性能较低,而维管束纤维复合板材较优。维管束纤维复合板材的弯曲弹性模量、静曲强度和抗拉强度分别达到了27.0 GPa、338.0 MPa和281.2 MPa;其比模量和比强度分别为24.1 GPa和302.3 MPa,超过了玻璃纤维增强铝合金层板,与芳纶铝合金层板相当,在工程结构领域具有较大应用前景。通过电子扫描显微镜观察板材端面结构发现,维管束纤维复合板材中维管束纤维之间存在明显的裂隙,在受载过程中易发生强度失效。因此,需进一步优化浸胶和热压工艺以提高其力学性能。

Developing a kind of high-strength bamboo-based panel and expanding its application in the field of engineered construction is an effective way to realize the concept of “building materials utilization of bamboo”. In this paper, the Dendrocalamus farinosus bamboo was processed into three scales of bamboo units including bamboo strips, bamboo bundles and vascular fibers. And four kinds of bamboo-based panels with different mat structure were pressed. The physical, mechanical properties and the cross-section structure of panels were analyzed. Results indicated that the thickness swelling, bending and tensile properties of all kinds of bamboo-based panels met the middle or upper grade requirements specified in GB/T 40247—2021 “Bamboo scrimber”. Among the four kinds of panel, the physical and mechanical properties of panel made of bamboo stripes are the worst, while those of the panel made of vascular fibers are the best. The bending elastic modulus, bending strength and tensile strength of the panel made of vascular fibers reached 27.0 GPa, 338.0 MPa and 281.2 MPa respectively. Its specific modulus and strength was 24.1 GPa and 302.3 MPa, which exceeds that of glass fiber reinforced aluminum alloy laminate(GLALL), and are equivalent to that of aramid aluminum alloy laminate(ARALL). It has a great prospect in the field of engineered constructions. However, the result of cross-section structure obtained by scanning electronic microscope(SEM) showed that there are obvious interlayer cracks between the vascular fibers in the panel. Thus, optimizing the adhesive spraying and hot pressing process shall be done to improve the mechanical properties.