论文总字数：18447字

摘 要

木塑复合材料是由木纤维与热塑性塑料复合而成的一种新型材料，天然纤维来源广泛，于环境无害，加上木塑复合材料性能上的诸多优势，受到材料行业的广泛关注。近年来，木塑复合材料在各国都有不小的发展，如木纤维预处理，助剂选择，接枝物的使用以及工艺设计等方面都已有了较成熟的体系。

本文就同种偶联剂、不同接枝率对木塑复合材料的制备与性能的影响进行相关研究。在木塑比为4:6，木粉粒径为80目，添加15%马来酸酐接枝物3%液体石蜡的条件下，比较不同接枝率的MAPP与MAHDPE做偶联剂对材料性能的影响。得出以下结论：1.在一定范围内，添加引发剂有利于MAHDPE接枝率的提高，但这样也会造成引发剂分解产生的自由基与HDPE发生交联作用，使材料熔体流动性下降；而提高螺杆转速不仅能提高接枝率同时还能提高材料熔体流动性能，使材料易于加工。2.当接枝物中所含游离酸酐量较多时，由于马来酸酐属于小分子，较多的游离酸酐会优先与木纤维表面的醇羟基反应，使得能与MAPP反应的羟基总量减少，并且可能会在木粉与基体之间形成小分子层，影响MAPP与基体及木粉之间结合，不利于材料性能的提高。3.相比于MAPP，MAHDPE与基体的相容性更好，可以明显发现添加MAHDPE的材料力学性能更佳，当接枝率为1.03%时，达到综合性能的最佳状态，此时拉伸强度为35.41MPa，弯曲强度37.29MPa，弯曲模量2140MPa，冲击强度22.78kJ·m^-2，缺口冲击强度3.77kJ·m^-2。

关键词：高密度聚乙烯 木纤维 力学性能 马来酸酐接枝物

Preparation and Property Research of HDPE/Wood Plastic Composite Material 
——effect of same coupling agent ,different grafting rate

Abstract

Wood plastic composite material is a new recombination made of wood fiber and thermoplastic polymer. Due to its extensive natural fiber sources , harmlessness to environment, combined with many property advantages, wood plastic composite material has received extensive attention from material industry.In recent years, wood plastic composite has developed a lot in many areas, such as the pretreatment of wood fiber , selection of addition agents , applications of grafting material and  process design and so on have been in mature systems.

In this paper,related research on the effect of preparation and properties of wood plastic composite,with  the same coupling agent and different grafting rates,has been carried out.We set that wood/plastic ratio is 4:6, wood powder particle size is 80 meshes, with 15% of maleic anhydride-grafted and 3% of liquid paraffin.In this condition ,MAPP and MAHDPE of different grafting rates have been used as coupling agents to research the influence on material properties.

After comparing the result ,we get such conclusions :First,within a certain range, adding initiating agent is beneficial to the improvement of the grafting rate of MAHDPE, while it can also cause cross linking between HDPE matrix and the free radicals rising from initiator decomposition, make the melt flow property drops.However,increasing the screw rotation speed could not only improve the grafting degree but also increase the melt flow property, making products easy to be processed. Second,when the quantity of free anhydrides contained in the graft is large,as small molecules, these free anhydrides are going to react prioritily with these alcoholic hydroxyl groups on the surface of  wood fibers. The amount of hydroxyl groups that can react with MAPP is reduced, and small molecule layer could be formed between the wood powder and the matrix, affecting the combination among MAPP, matrix and wood powder ,which is not conducive to the improvement of the performance of the composites.Third,compared with the MAPP, MAHDPE has better compatibility with matrix , it can be obviously found that adding MAHDPE makes material mechanics ptoperties better.When the grafting rate is 1.03%, we get the best comprehensive performance of composites  : the tensile strength of 35.41 MPa, the bending strength of 37.29 MPa, the bending modulus of 2140 MPa, the impact strength of 22.78 kJ ·m^{- 2}, notched impact strength of 3.77 kJ· m^{- 2}.

Key words : High density polyethylene ; Wood fiber ; Mechanical properties ;

Maleic anhydride-grafted

目录

摘要 I

Abstract II

第一章 绪论 1

1.1引言 1

1.2 木塑复合材料 2

1.2.1木塑复合材料的用途及其特点 2

1.2.2木塑复合材料的原料及其对性能的影响 2

1.2.3木塑复合材料加工工艺及技术进展 3

1.2.4木塑复合材料改性工艺 4

1.3研究内容与工艺路线 6

1.4本论文研究意义和内容 6

第二章 实验部分 8

2.1实验仪器与设备 8

2.2实验材料及方法 8

2.2.1实验材料 8

2.2.2 MAHDPE的制备 8

2.2.3试样制备过程 9

2.2.4木塑复合材料性能测试 10

第三章 结果与讨论 12

3.1接枝物的性质 12

3.2所得木塑复合材料性能 14

3.2.1拉伸强度 14

3.2.2弯曲强度及弯曲模量 15

3.2.3冲击强度及缺口冲击强度 16

第四章 结论 18

参考文献 19

致谢 21

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