【作者】 张丽；

【导师】 母军；

【作者基本信息】 北京林业大学 ， 木材科学与技术， 2017， 硕士

【摘要】 为解决玉米秸秆资源浪费、润湿性差以及玉米秸秆复合材料内结合强度低的问题,本研究首先对玉米秸秆皮及穣进行表面微观观察及元素分析,然后以玉米秸秆为试验材料,将其疏解成丝状结构单元,分别以脲醛树脂和异氰酸酯为胶黏剂,对其进行定向、随机铺装,研究铺装结构、施胶量及长(丝状结构单元的长度)厚(板材的厚度)比对玉米秸秆复合茎丝板性能的影响,为后期玉米秸秆轻质墙体材料的研究奠定基础。主要结果及结论如下:(1)玉米秸秆皮外表面的初始接触角明显大于内表面,且随时间推移基本不变,外表面Si含量高且分布均匀,内外表面润湿性存在较大差异。(2)定向铺装可以提高玉米秸秆复合茎丝板的物理力学性能。相同密度下,以脲醛树脂为胶黏剂的定向玉米秸秆复合茎丝板(OCSB)的纵向静曲强度(MOR//)、纵向弹性模量(MOE//)和内结合强度(IB)均大于以脲醛树脂为胶黏剂的随机铺装的均向玉米秸秆复合茎丝板(HCSB),MOR//和MOE//约为HCSB的3倍,IB约为4-5倍,且OCSB的吸水率和吸水厚度膨胀率均小于HCSB。(3)相比以脲醛树脂为胶黏剂的定向玉米秸秆复合茎丝板(OCSB),以异氰酸酯为胶黏剂的定向玉米秸秆复合茎丝板(MOCSB)防水性能和力学强度都明显提高。密度为0.3 g/cm3时,施胶量3%的MOCSB吸水厚度膨胀率相比OCSB下降约60%,MOR//约增加1倍,内结合强度约增加2倍。(4)随密度增加,MOCSB的热阻降低,导热系数增大,施胶量对玉米秸秆复合茎丝板热传导性能影响不大,各个实验条件下MOCSB的导热系数均小于0.12 W/(m·K),达到保温材料要求。所有实验条件下玉米秸秆复合茎丝板的降噪系数约为0.44-0.51,均大于吸声材料最低标准0.2。利用玉米秸秆能够制备出力学及声热性能优良的复合材料,能够满足建筑用吸音保温人造板的使用需求。(5)结构单元长度与板材厚度比的增加改善了玉米秸秆复合茎丝板的静曲强度和弹性模量,长厚比为2的玉米秸秆复合茎丝板的内结合强度明显优于长厚比为3、4的板材。更多还原

【Abstract】 In order to solve the waste of cornstalk resources,poor wettability and low internal bond strength of cornstalk composites,in this study,the cornstalk was used as the experimental material,the microstructure of cornstalk was observed,the elemental composition of skin and pith were analyzed,then the cornstalk was eased into filamentous structures,urea formaldehyde resin and isocyanate were used as adhesive respectively,these filamentous structures were used to fabricate the composite by different formation mode of orientation and non-orientation.The effects of pavement structure,resin content and length-thick ratio on the properties of cornstalk composites were studied.This study laid the foundation for the study of the light weight wall material of cornstalk.The main results and conclusions are as follows:(1)The initial contact angle of the outer surface of cornstalk was significantly higher than that of the inner surface,and the contact angle of the outer surface unchanged with the time,the content of Si on the outer surface is high and evenly distributed.There is a big difference between the inner and outer surface of wettability.(2)The physical and mechanical properties were improved by orientional formation.Under the same density,the modulus of longitudinal rupture(MOR//),modulus of longitudinal elasticity(MOE//)and internal bond strength(IB)of the orientional composite silk board of cornstalk which used urea-formaldehyde resin adhesive(OCSB)were higher than that of homogeneous composite silk board of cornstalk(HCSB).The MOR//and MOE//values of OCSB were about 3 times,and the IB value was about 4-5 times,as much as HCSB with the same density.In addition,the water absorption(WA)and thickness swelling(TS)of OCSB were smaller than HCSB.(3)Compared with the OCSB,the water resistance and mechanical strength of the orientional composite silk board of cornstalk which used isocyanate adhesive(MOCSB)were obviously improved.The TS of the MOCSB which the resin content is 5%and the density is 0.6 g/cm3 decreased by 60%compared to OCSB,the MOR//increased about 1 times and the IB increased about 2 times.(4)With the increase of density,the thermal resistance of MOCSB decreased and the thermal conductivity(TC)increased,the resin content had a little influence on heat conducting performance of the MOCSB,TC of the MOCSB under all experimental conditions were less than 0.12 W/(m K),which satisfied the requirements of thermal insulation materials.Noise reduction coefficient of all MOCSB was 0.44 to 0.51,which was greater than the minimum standard of 0.2 of sound-absorbing material.The composite silk board of cornstalk which were prepared with cornstalk have fine mechanical and sound thermal properties,and it can meet the requirements of the building sound-absorbing insulation composites.(5)The MOR and MOE of composite silk board of cornstalk were improved with the increase of the ratio of the length of the structural unit and the thickness of the composites,When the the ratio of length to thickness is 2,the IB of the composite silk board of cornstalk is obviously better than that of 3 and 4.更多还原