木粉/高密度聚乙烯发泡复合材料的研究
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摘要
木塑复合材料(WPC)是指将木质纤维填料(包括木粉、秸秆、稻壳等)以粉状、纤维状和刨花等形态作为增强物或填料加入到热塑性或热固性塑料中进行复合得到的新型功能材料。由于该种材料综合了木材与塑料的性能特点，因而具有非常广泛的用途。
本论文以高密度聚乙烯(HDPE)树脂为基体，木粉为主要填料，对木塑复合材料中的主要加工助剂的种类和用量进行了深入的探讨。研究了木塑发泡材料的组成与性能、结构之间的关系。通过扫描电镜(SEM)照片观察所得试样的微观形态和泡孔结构。初步地研究了挤出过程中的工艺参数螺杆转速、挤出温度对材料发泡性能的影响。
通过对上述研究内容的分析和讨论，获得以下主要结论：
1．研究了木粉／HDPE复合材料中木粉含量及偶联剂的对复合材料各项力学性能的影响。发现随着木粉的加入，同纯树脂相比，冲击强度和拉伸强度都迅速下降。在所研究的范围内，木粉用量为100份至150份(以HDPE用量为标准)时较为适中；通过比较未用偶联剂处理的木粉与用偶联剂处理的木粉制得的材料的力学性能，发现用偶联剂处理木粉后所得的材料比未加偶联剂的，在力学性能上有一定程度的提高，但效果并不是很理想，其中硅烷偶联剂相对来说，处理效果较好，其最佳用量为5％(以木粉用量为标准)。
2．研究了四种不同增容剂乙烯．醋酸乙烯共聚物(EVA)、乙烯丙烯酸共聚物(EAA)、马来酸酐改性聚丙烯(MA-PP)、马来酸酐改性聚乙烯(MA-PE)对木粉／HDPE复合材料力学性能的影响。试验结果表明：对于HDPE／木粉复合体系，除了EVA外，所加入的其他三种增容剂均比较显著的提高了复合材料的力学性能。其中EAA和MA-PE的对体系的改善效果相近，而MA-PP则是最有效的增容剂，当MA-PP用量为9份时，材料的各项力学性能达到最佳；此外，还比较了两种常用的增韧弹性体三元乙丙橡胶(EPDM)和苯乙烯-丁二烯-苯乙烯(SBS)对木粉／HDPE复合材料的增韧效果，实验结果表明：加入弹性体后，所得复合材料的冲击韧性都有所提高，而且随弹性体用量的增加而增大，但材料的弯曲强度也有所下降。在所选的两种弹性体中，EPDM对冲击强度的改善作用优于SBS。
3．采用模压发泡法通过对复合材料进行发泡，通过DSC分析比较发现：采用放热型发泡剂AC和吸热型发泡剂NaHCO_3混合配制的复合发泡剂能有效地改善因使用纯放热发泡剂AC而造成的并泡或难于发泡现象，也有利于制品性能的提高；对木粉／HDPE复合材料进行化学发泡后的实验结果表明：发泡的复合材料不仅在密度上比未发泡材料有着显著的降低(比未发泡材料下降25％左右)，而且对材料的抗冲击性能也有一定的改善；另外，通过和几种常用木材进行比较发现，发泡的复合材料在握钉力和静压力方面已经基本接近于某些常用木材。
4．初步研究了木粉／HDPE复合材料的发泡挤出成型过程。通过设定不同的挤出工艺参数对木粉／HDPE复合材料性能的影响，探讨了复合体系挤出成型性能的工艺因素。试验结果表明，当螺杆转速控制在12rpm左右时，即可保证一定的反应时间，又可避免物料在螺杆中因长期滞留而引起的木粉焦化和HDPE基体过分降解；挤出口模的温度宜控制在HDPE熔点附近，因为这样可使熔体强度因温度骤降而急剧上升，从而实现较好的发泡状态。在口模出口处，对挤出发泡物进行强制冷却，可改善泡体表面质量、泡孔结构和泡体机械性能。
Wood-plastics composites are a kind of new material, which are formed by wood, wood fiber(including wood flour, straw, shell of paddy) or other lignocellulose fibers with various plastics in different combining paths. With the integrating performance characteristic of wood and plastics, the new material will be utilized in very extensive field.
In this paper, the optimum contents of the additives in HDPE/wood flour composite was investigated. Based on the fore-going formulation, the relationship between the composition, the structure and properties of HDPE/wood flour composite foams was studied systematically. Depending on the SEM micrographs, to observe the microcosmic configuration and structure of foam. In addition, the pilot study on the craftwork parameter such as rev of screw and temperature of machine foreside how to affect property of foam.
The main works and conclusions were listed as following:
1. HDPE /wood flour composite was prepared from HDPE and wood flour, the effects of the content of the wood flour, the effects of the type and content of surface treatment agent on the properties of WPC were studied. The results showed that the overall property of the composite was the optimum when the content of the wood flour was 100-150 phr, and the best content of the coupling agent was 5 % of the mass weight of the wood flour.
2. Reserching the effects on the Mechanical Properties Of Wood-Plastics-Composite resulted by four different kind compatibilizers EVA、 EAA、MA-PP、MA-PE. According to the Mechanical Properties and microcosmic physiognomy's testing result, it can be concluded that, firstly, rigidity of composite-materials has been increased, but tenacity fallen because of wood-powder being added; secondly, the Mechanical Properties of composite-materials with the addition of the Silane coupling agent are preferable; finally, MA-PP gave the best combined properties. Moreover, compared the effect of improving tenacity brought by two common used elastomers EPDM and SBS. The results showed that tenacity of composite materials has been improved after mixing inte elastomers and EPDM better than SBS.
3. Foaming composite materials by adopting foaming method by used mould. After DSC analysis discovered that the use of chemical foaming agent(CFA) could decrease the specific weight of the composite effectively and improve the impact of the composite material. As to the blowing effect, the endothermic-exothermic balanced CFA was better than exothermic CFA. In addition, depending on comparing composite material and some common used wood, it is showed that in holding nail and static tension foaming-composite material is almost as well as some common used wood.
4. Studied the extruding course of foaming-composite material, and then discussed the craftwork parameter how to affect the mechanical properties of foaming-composite-materials. The results showed that rev of screw should be set about 12 rpm and temperature of machine foreside controlled in the range near melting point of HDPE in that can make the mechanical properties of composite-materials best.
本论文以高密度聚乙烯(HDPE)树脂为基体，木粉为主要填料，对木塑复合材料中的主要加工助剂的种类和用量进行了深入的探讨。研究了木塑发泡材料的组成与性能、结构之间的关系。通过扫描电镜(SEM)照片观察所得试样的微观形态和泡孔结构。初步地研究了挤出过程中的工艺参数螺杆转速、挤出温度对材料发泡性能的影响。
通过对上述研究内容的分析和讨论，获得以下主要结论：
1．研究了木粉／HDPE复合材料中木粉含量及偶联剂的对复合材料各项力学性能的影响。发现随着木粉的加入，同纯树脂相比，冲击强度和拉伸强度都迅速下降。在所研究的范围内，木粉用量为100份至150份(以HDPE用量为标准)时较为适中；通过比较未用偶联剂处理的木粉与用偶联剂处理的木粉制得的材料的力学性能，发现用偶联剂处理木粉后所得的材料比未加偶联剂的，在力学性能上有一定程度的提高，但效果并不是很理想，其中硅烷偶联剂相对来说，处理效果较好，其最佳用量为5％(以木粉用量为标准)。
2．研究了四种不同增容剂乙烯．醋酸乙烯共聚物(EVA)、乙烯丙烯酸共聚物(EAA)、马来酸酐改性聚丙烯(MA-PP)、马来酸酐改性聚乙烯(MA-PE)对木粉／HDPE复合材料力学性能的影响。试验结果表明：对于HDPE／木粉复合体系，除了EVA外，所加入的其他三种增容剂均比较显著的提高了复合材料的力学性能。其中EAA和MA-PE的对体系的改善效果相近，而MA-PP则是最有效的增容剂，当MA-PP用量为9份时，材料的各项力学性能达到最佳；此外，还比较了两种常用的增韧弹性体三元乙丙橡胶(EPDM)和苯乙烯-丁二烯-苯乙烯(SBS)对木粉／HDPE复合材料的增韧效果，实验结果表明：加入弹性体后，所得复合材料的冲击韧性都有所提高，而且随弹性体用量的增加而增大，但材料的弯曲强度也有所下降。在所选的两种弹性体中，EPDM对冲击强度的改善作用优于SBS。
3．采用模压发泡法通过对复合材料进行发泡，通过DSC分析比较发现：采用放热型发泡剂AC和吸热型发泡剂NaHCO_3混合配制的复合发泡剂能有效地改善因使用纯放热发泡剂AC而造成的并泡或难于发泡现象，也有利于制品性能的提高；对木粉／HDPE复合材料进行化学发泡后的实验结果表明：发泡的复合材料不仅在密度上比未发泡材料有着显著的降低(比未发泡材料下降25％左右)，而且对材料的抗冲击性能也有一定的改善；另外，通过和几种常用木材进行比较发现，发泡的复合材料在握钉力和静压力方面已经基本接近于某些常用木材。
4．初步研究了木粉／HDPE复合材料的发泡挤出成型过程。通过设定不同的挤出工艺参数对木粉／HDPE复合材料性能的影响，探讨了复合体系挤出成型性能的工艺因素。试验结果表明，当螺杆转速控制在12rpm左右时，即可保证一定的反应时间，又可避免物料在螺杆中因长期滞留而引起的木粉焦化和HDPE基体过分降解；挤出口模的温度宜控制在HDPE熔点附近，因为这样可使熔体强度因温度骤降而急剧上升，从而实现较好的发泡状态。在口模出口处，对挤出发泡物进行强制冷却，可改善泡体表面质量、泡孔结构和泡体机械性能。
Wood-plastics composites are a kind of new material, which are formed by wood, wood fiber(including wood flour, straw, shell of paddy) or other lignocellulose fibers with various plastics in different combining paths. With the integrating performance characteristic of wood and plastics, the new material will be utilized in very extensive field.
In this paper, the optimum contents of the additives in HDPE/wood flour composite was investigated. Based on the fore-going formulation, the relationship between the composition, the structure and properties of HDPE/wood flour composite foams was studied systematically. Depending on the SEM micrographs, to observe the microcosmic configuration and structure of foam. In addition, the pilot study on the craftwork parameter such as rev of screw and temperature of machine foreside how to affect property of foam.
The main works and conclusions were listed as following:
1. HDPE /wood flour composite was prepared from HDPE and wood flour, the effects of the content of the wood flour, the effects of the type and content of surface treatment agent on the properties of WPC were studied. The results showed that the overall property of the composite was the optimum when the content of the wood flour was 100-150 phr, and the best content of the coupling agent was 5 % of the mass weight of the wood flour.
2. Reserching the effects on the Mechanical Properties Of Wood-Plastics-Composite resulted by four different kind compatibilizers EVA、 EAA、MA-PP、MA-PE. According to the Mechanical Properties and microcosmic physiognomy's testing result, it can be concluded that, firstly, rigidity of composite-materials has been increased, but tenacity fallen because of wood-powder being added; secondly, the Mechanical Properties of composite-materials with the addition of the Silane coupling agent are preferable; finally, MA-PP gave the best combined properties. Moreover, compared the effect of improving tenacity brought by two common used elastomers EPDM and SBS. The results showed that tenacity of composite materials has been improved after mixing inte elastomers and EPDM better than SBS.
3. Foaming composite materials by adopting foaming method by used mould. After DSC analysis discovered that the use of chemical foaming agent(CFA) could decrease the specific weight of the composite effectively and improve the impact of the composite material. As to the blowing effect, the endothermic-exothermic balanced CFA was better than exothermic CFA. In addition, depending on comparing composite material and some common used wood, it is showed that in holding nail and static tension foaming-composite material is almost as well as some common used wood.
4. Studied the extruding course of foaming-composite material, and then discussed the craftwork parameter how to affect the mechanical properties of foaming-composite-materials. The results showed that rev of screw should be set about 12 rpm and temperature of machine foreside controlled in the range near melting point of HDPE in that can make the mechanical properties of composite-materials best.
引文
[1] 杨庆贤．复合材料学报，1994，11，4：9-13
[2] 丁建生，等．现代塑料加工应用，2003，15(1)：16
[3] 薛平，贾明印，王哲等．PVC／木粉复合材料挤出发泡成型的研究．工程塑料应用，2004，32(12)：66~70
[4] Matuana L M, Park C B, Balatinecz J J Polym Eng Sci, 1998, 38(11): 1862
[5] Matuana L M, Park C B, Balatinecz J J. Annu Tech Conf ANTEC Conf Proc, 1996,(2): 1900
[6] Matuana L M, Park C B, Balatinecz J J. ASME Mater Div PubMD, 1996, 74:199
[7] Mengeloglu F, Matuana L M. J Vinyl Addit Technol, 2003, 9(1): 26
[8] Lin H R, Shau M D, Chiou Z W. J Polym Res, 2001, 8 (4): 241
[9] 国明成，王洪，彭玉成．PVC／木纤维微孔发泡技术的研究．工程塑料应用塑料，200231(4)：20-24
[10] 苑会林，李运德，闫雪晶等．聚氯乙烯，2002，(6)：29
[11] Lin, Hong-Ru; Shau, Min-Da; Chiou, Zen-Wen. Mechanical characterization of microcellular foamed PVC/wood-flour composites. J. Polym. Reseach. 2001, 8:241-251
[12] 钟鑫，薛平，丁筠等．中国塑料，2004，18(3)：62
[13] 蔡剑平．中国塑料，2004，18(6)：54
[14] Paladugula J, Shutov F. Annu Tech Conf ANTEC Conf Proc, 1998, (2): 1855
[15] Li Q X, Matuana L M. J Appl Polym Sci, 2003, 88:31-39
[16] Rachtanapun, P; Selke, S. E. M; Matuana, L. M. Microcellular foam of polymer blends or HDPE/PP and their composites with wood fiber. J. Appl. Polym. Sci, 2003,88, 2842-2850
[17] 蔡剑平．中国塑料，2004，18(6)：5
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[25] Rizvi G M, Park C B, Lin W S, etal. Polym Eng Sci, 2003, 43(7): 1347
[26] 薛平．工程塑料应用，2004，32(12)：66
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[28] Zhang H, Rizvi G M, Park C B. Adv Polym Technol, 2004, 23(4): 263
[29] Rizvi G M, Pop Iliev R, Park C B. J Cell Plast, 2002,38(5): 367
[30] Matuana L M; Li Qingxiu. Statistical Modeling and Response Surface Optimization of Extruded HDPE/wood-Flour Composite Foams. J Thermoplast Compos Mater. 2004, 17, 185~199
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[32] John Z Lu; Wu QingLin; Harold S. Chemical Coupling in wood Fiber and Polymer Composites: A Review of Coupling Agents and treatments. Wood Science and technology, 2000,32(1): 88～104
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[2] 丁建生，等．现代塑料加工应用，2003，15(1)：16
[3] 薛平，贾明印，王哲等．PVC／木粉复合材料挤出发泡成型的研究．工程塑料应用，2004，32(12)：66~70
[4] Matuana L M, Park C B, Balatinecz J J Polym Eng Sci, 1998, 38(11): 1862
[5] Matuana L M, Park C B, Balatinecz J J. Annu Tech Conf ANTEC Conf Proc, 1996,(2): 1900
[6] Matuana L M, Park C B, Balatinecz J J. ASME Mater Div PubMD, 1996, 74:199
[7] Mengeloglu F, Matuana L M. J Vinyl Addit Technol, 2003, 9(1): 26
[8] Lin H R, Shau M D, Chiou Z W. J Polym Res, 2001, 8 (4): 241
[9] 国明成，王洪，彭玉成．PVC／木纤维微孔发泡技术的研究．工程塑料应用塑料，200231(4)：20-24
[10] 苑会林，李运德，闫雪晶等．聚氯乙烯，2002，(6)：29
[11] Lin, Hong-Ru; Shau, Min-Da; Chiou, Zen-Wen. Mechanical characterization of microcellular foamed PVC/wood-flour composites. J. Polym. Reseach. 2001, 8:241-251
[12] 钟鑫，薛平，丁筠等．中国塑料，2004，18(3)：62
[13] 蔡剑平．中国塑料，2004，18(6)：54
[14] Paladugula J, Shutov F. Annu Tech Conf ANTEC Conf Proc, 1998, (2): 1855
[15] Li Q X, Matuana L M. J Appl Polym Sci, 2003, 88:31-39
[16] Rachtanapun, P; Selke, S. E. M; Matuana, L. M. Microcellular foam of polymer blends or HDPE/PP and their composites with wood fiber. J. Appl. Polym. Sci, 2003,88, 2842-2850
[17] 蔡剑平．中国塑料，2004，18(6)：5
[18] Bledzki A K, Faruk O. Cell Polym, 2002, 21(6): 417
[19] Bledzki A K, Faruk O. Cell Polym, 2004, 23(4): 211
[20] Matuana L, Li Q. Cell Polym, 2001, 20(2): 115
[21] Rizvi G, Matuana L M, Park C B. Polym Eng Sci, 2000, 4(10): 21-24
[22] Doroudiani S, Kortschot M T. J Thermoplast Compos Mater, 2004, 17(1): 13
[23] Doroudiani S, Chaffey C E, Kortschot M T. J Polym Sci, Part B: Polym Phys,2002, 40(8): 723
[24] Krishnamurthi B, Bharadwaj Somaskandan S, Sergeeva T, etal. Cell Polym,2003, 22(6): 371
[25] Rizvi G M, Park C B, Lin W S, etal. Polym Eng Sci, 2003, 43(7): 1347
[26] 薛平．工程塑料应用，2004，32(12)：66
[27] Guo G, Rizvi G M, Park C B, etal. J Appl Polym Sci, 2004, 91(1): 621
[28] Zhang H, Rizvi G M, Park C B. Adv Polym Technol, 2004, 23(4): 263
[29] Rizvi G M, Pop Iliev R, Park C B. J Cell Plast, 2002,38(5): 367
[30] Matuana L M; Li Qingxiu. Statistical Modeling and Response Surface Optimization of Extruded HDPE/wood-Flour Composite Foams. J Thermoplast Compos Mater. 2004, 17, 185~199
[31] 邬义明主编．植物纤维化学，北京：中国轻工业出版社，2000．3～5
[32] John Z Lu; Wu QingLin; Harold S. Chemical Coupling in wood Fiber and Polymer Composites: A Review of Coupling Agents and treatments. Wood Science and technology, 2000,32(1): 88～104
[33] A K Bledzki, et al. Polym-Plast. Technol. Eng. 1998, 37(4): 451～468
[34] C A S Hill, et al. International Journal of Adhesion and Adhesives, 2000 (20): 71～76
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