环境友好型秸秆复合材料的制备与性能研究

发布时间：2018-03-14 00:55

本文选题：秸秆纤维复合材料　切入点：相容剂　出处：《湖北工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：使用农业废弃物秸秆制成的秸秆纤维复合材料可以代替一部分实木材料,可有效地缓解我国的森林资源压力,体现绿色环境友好型材料的理念。在我国面临的资源短缺和生态环境日益恶劣的背景下,低碳减排的要求被越来越重视,SPC作为一个新兴的绿色环保产品,引起了各国学者的研究兴趣,但仍然未取得重大成果,这将是建设可持续发展的一个分支方向。由于秸秆表面有一层二氧化硅和蜡质层,影响了胶黏剂对其表面的润湿。未经处理的纤维具有吸湿性和较强的极性,使其与非极性树脂间界面润湿性、粘结性变差,随着时间推移会发生剥落。本文着重讨论了三种处理方法对秸秆纤维复合材料相容性及力学性能的影响与表征。通过对秸秆纤维/LDPE体系内加入相容剂,使得秸秆纤维的分散状况与秸秆纤维与树脂的缠结情况发生了转变。复合材料的力学性能得到了一定的改善。通过实验室流变仪手段,对复合材料熔体的流变行为进行研究分析得出,秸秆纤维与相容剂会使得体系内部构成三维网络的复杂结构,使得体系松弛时间增大分子链松弛更困难。当秸秆纤维填充量过大的时候,相容剂可以大大减小基体分子链的松弛时间,由405 s降低到214 s。碱脲分离型预处理秸秆纤维的处理方法,能够较好地除去秸秆纤维表面的蜡质层,打断秸秆内部缠结的纤维素大分子,溶出内部的木质素和灰分。在一定范围内,增强了秸秆纤维与MDI胶黏剂的胶结强度,冲击强度由1200 J/m2提高到2036 J/m2;弯曲强度由3.78 MPa提升到9.86 MPa。对于树脂体系来说,洗净的碱脲分离型秸秆纤维降低了树脂基体的结晶度,而未除去碱脲小分子的秸秆纤维样品却提升了树脂基体的结晶度,从而影响了复合材料的宏观力学性能。废旧报纸经过预处理后得到纤维素含量极高的回收纤维素纤维,回收纤维素具有较大的长径比,较高的结晶度,密度小,不易分散容易自缠结。回收纤维素与秸秆纤维复配为纤维填料,与MDI胶黏剂压制成的板材,弯曲模量提高了30%,弯曲强度增加了100%,冲击强度增加了40%。经过苯乙烯单体包覆的MDI纤维板体系,吸水厚度膨胀率下降为原来的0.6倍,苯乙烯添加量为7 wt%时MDI纤维板的性能最优。回收纤维素含量为2 wt%时树脂复合样品的物理性能最优。植物纤维的加入会促进树脂基体分子链的异相成核作用,结晶速率较HDPE大,并且在回收纤维素为2 wt%时,异相成核作用更明显,且加速了树脂基体分子链的结晶行为。
[Abstract]:The straw fiber composite made from agricultural waste straw can replace some solid wood materials and can effectively relieve the pressure of forest resources in China. Reflecting the concept of green environment-friendly materials. Under the background of the shortage of resources and the increasingly bad ecological environment in China, the demand of low carbon emission reduction has been paid more and more attention to as a new green environmental protection product. It has aroused the interest of scholars from all over the world, but it has not made great achievements, which will be a branch of sustainable development, because there is a layer of silica and wax on the surface of straw. The surface wettability of the adhesive is affected. The untreated fibers have the characteristics of moisture absorption and strong polarity, which make the interfacial wettability between the fibers and non-polar resins become worse. In this paper, the effect and characterization of three treatment methods on the compatibility and mechanical properties of straw fiber composites are discussed. By adding compatibilizer into straw fiber / LDPE system, The dispersion of straw fiber and the entanglement between straw fiber and resin have been changed. The mechanical properties of composite materials have been improved to some extent, and the mechanical properties of the composites have been improved by means of laboratory rheometer. The rheological behavior of composite melt is studied and analyzed. It is concluded that straw fiber and compatibilizer will make the complex structure of three-dimensional network in the system. When the amount of straw fiber is too large, the compatibilizer can greatly reduce the relaxation time of matrix molecular chain. From 405 s to 214 s. The treatment method of pretreatment straw fiber with alkali urea can remove the waxy layer on the surface of straw fiber and interrupt the cellulose macromolecule which is entangled inside the straw. The internal lignin and ash were dissolved. In a certain range, the binding strength of straw fiber and MDI adhesive was enhanced, the impact strength was increased from 1200J / m2 to 2036J / m2, and the bending strength was increased from 3.78 MPa to 9.86MPa. for the resin system, The degree of crystallinity of resin matrix was decreased by washing alkali urea separated straw fiber, but the crystallinity of resin matrix was increased by the sample of straw fiber without removing alkali-urea small molecule. After pretreatment, the recycled cellulose fiber with high cellulose content was obtained. The recycled cellulose had higher aspect ratio, higher crystallinity and lower density. It is difficult to disperse easily self-entangled. Recycled cellulose and straw fiber mixed as fiber filler, pressed with MDI adhesive plate, The flexural modulus increased by 30%, the flexural strength increased by 100%, the impact strength increased by 40%. After the styrene monomer coated MDI fiberboard system, the water absorption thickness expansion rate decreased 0.6 times. The properties of MDI fiberboard were optimized when styrene content was 7 wt%, and the physical properties of resin composite sample was optimized when the content of recycled cellulose was 2 wt%. The addition of vegetable fiber could promote the heterogeneous nucleation of resin matrix molecular chain. The crystallization rate is higher than that of HDPE, and the heterogeneous nucleation is more obvious when the recovery rate of cellulose is 2 wt%, and the crystallization behavior of resin matrix molecular chain is accelerated.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ914.3;TB33

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