木基缠绕管道结构层的制备及其力学性能

Preparation and mechanical properties of wood-based winding pipe structural layer

木基缠绕管道是以木材为结构层、纤维增强树脂复合材料为内衬层和外防护层的新型绿色低碳输送管道,但其制备工艺还不成熟。由于木基缠绕管道的结构层材料为无纺布增强杨木单板带,且结构层的物理力学性能对木基缠绕管道尤为重要,所以笔者以木基缠绕管的结构层(不包括内外保护层)为对象,研究木基缠绕管道结构层的制备工艺。使用10和16 cm宽无纺布增强杨木单板带和酚醛树脂、环氧树脂制备4种类型木基缠绕管道的结构层,评价了含水率对无纺布增强单板带拉伸强度的影响,对比了2种胶黏剂在增强单板带上的动态接触角,基于单板带宽与缠绕角度存在数学关系,单板带宽10与16 cm分别对应缠绕角度6.09°与9.78°,分析了缠绕角度和胶黏剂类型对木基缠绕管道结构层的环刚度、环向拉伸强度及轴向拉伸强度的影响,测试了4种木基缠绕管道结构层的耐水性能。结果显示,无纺布增强单板带接长处比非接长处的拉伸强度小,单板带拉伸强度与含水率呈负相关,制备木基缠绕管道结构层时增强单板带含水率不宜高于12%。环氧树脂比酚醛树脂制备的木基缠绕管道结构层的环刚度、环向拉伸强度及轴向拉伸强度大,缠绕角度从6.09°增加到9.78°时,木基缠绕管道结构层的环刚度和环向拉伸强度降低,轴向拉伸强度提高。制备的4种木基缠绕管道结构层均能满足Ⅱ类胶合板的耐水性能要求,为优化新型速生杨木基缠绕输送管道的生产工艺提供数据参考和理论依据。

Wood winding pipe is a type of natural renewable biomass products, which possesses the advantages of high strength, good shock resistance, corrosion resistance, renewable and low cost, having good prospect in the green renewable pipe markets. However, the wood winding pipe has not yet reached the stage of mass production and widely applications, mainly because its preparation process is still problematic. Since the structural layer material of the wood winding pipe is non-woven reinforced poplar veneer curtains, and the physical and mechanical properties of the structural layer are particularly important for the wood winding pipe, this study used the structural layer of the wood win-ding pipe(excluding the internal and external protective layer) as the test example, to explore the preparation process of wood winding pipe. The non-woven reinforced poplar veneer curtains with widths of 10 and 16 cm, the phenolic resin and epoxy resin were used to prepare four types of wood winding pipe. An equation was developed to describe the relationship between the veneer width and the winding angle. The veneer widths of 10 and 16 cm of the pipeline structure layer corresponded to 6.09° and 9.78°, respectively. Firstly, the physical and mechanical properties of the poplar veneer curtain, which was the preparation material of wood winding pipe structure layer, were studied, mainly including the influence of moisture content on the tensile strength of non-woven reinforced veneer curtains and the comparison of dynamic contact angles of two adhesives on the reinforced veneer curtains. Then, the tensile, flexural and water-resistant properties of the four kinds of wood-winding pipe structural layers were explored, mainly including the ring stiffness, circumferential tensile strength, and axial tensile strength of the wood winding pipe structural layer by the winding angle of the veneer and the type of adhesive. The water resistance of the four kinds of wood winding pipe structural layers was tested. The results showed that the tensile strength of the non-woven reinforced veneer was lower than that of the unjoined part, and the tensile strength of the veneer was negatively correlated with the moisture content. The moisture content of the reinforced veneer curtains should not be higher than 12% when preparing the wood winding pipe structure layer. Compared with the phenolic resin, the ring stiffness, circumferential tensile strength, and axial tensile strength of epoxy resin of the wood winding pipe structure layer were higher, and when the winding angle increased from 6.09° to 9.78°, the ring stiffness and circumferential tensile strength of the wood winding pipe structure layer decreased, and the axial tensile strength increased. The four wood-winding pipe structural layers prepared in this study could meet the water resistance requirements of Type II plywood according to Chinese national standard. The results of this study can provide a theoretical basis for the design of wood winding pipes and can also promote the upgrading of the poplar processing industry and regional economic development, thereby helping the ecological construction of large-scale water supply and drainage projects and municipal engineering.