【作者】 张玲；

【导师】 房轶群；

【作者基本信息】 东北林业大学 ， 林业工程（生物质复合材料）， 2022， 硕士

【摘要】 作为一种新型绿色环保材料,木塑复合材料(WPC,Wood Plastic Composites)具有原木特有的木质感,良好的机械性能、尺寸稳定性等众多优点,其被广泛应用于交通运输、建筑行业、包装等领域。WPC的广泛应用是循环再利用废旧塑料和废弃木质资源的一个发展方向,具有广阔的市场和良好的发展前景。但是,WPC的主要组分木粉和大多数树脂都是易燃的,其对WPC的应用产生了不利的影响,因此对WPC进行阻燃处理愈发重要。传统阻燃剂在对WPC阻燃时往往会对WPC的力学性能产生不利的影响,如能同时提高WPC的阻燃性能和力学性能,将很大程度上提升WPC的附加值,拓宽其在生活中的应用领域。针对上述问题,本文以木粉填充量为60%的聚丙烯(PP)基WPC为研究对象,首先合成了八氨丙基笼型倍半硅氧烷(OA-POSS),通过熔融共混热压制备OA-POSS阻燃的WPC,其次,将9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)改性成带有羧基的衍生物(DPA),将DPA与OA-POSS复配阻燃WPC,以获得性能更优异的WPC。最后,探究阻燃剂不同加入方式对WPC性能的影响。探究阻燃剂添加量,复配配比及不同添加方式对WPC热稳定性能,阻燃性能,静态力学性能,动态力学性能和短期蠕变性能的影响,本文的主要研究内容和结果如下:(1)通过3-氨丙基三乙氧基硅烷(KH-550)水解缩合成OA-POSS。热重分析表明,OA-POSS在800 ~oC时的残炭量为54.6%,充分显示了OA-POSS的耐高温性能。通过熔融共混法制备OA-POSS阻燃WPC。测试结果表明:OA-POSS含量越多,WPC的热稳定性和阻燃性能就越好。当OA-POSS含量为20%时,WPC的热释放速率峰值(PHRR)和总热释放(THR)分别下降了20.6%,3.0%,残炭量提升了260.9%。随着OA-POSS含量的增加WPC的静态力学性能先上升后下降,OA-POSS含量为15%时,WPC的力学性能最佳,其弯曲强度和冲击强度分别提升了16.4%,63.5%。OA-POSS的添加提高了WPC的储能模量和抗蠕变性能,降低了WPC的损耗因子,这是由于作为刚性粒子的OA-POSS与PP有良好的相容性,在WPC中承担增强体作用,材料刚性增强。但高含量的OA-POSS在熔融共混中易造成团聚,进而影响WPC的力学性能。(2)在保持阻燃剂总含量为15%的条件下,通过熔融共混法制备DPA与OA-POSS复配阻燃WPC。测试结果表明:DPA与OA-POSS在WPC中发挥了良好的协同作用,DP3-1(DPA与OA-POSS质量比为3:1的WPC)的热稳定性和阻燃性能最好。DP3-1的PHRR和THR分别下降了20.7%,12.5%,残炭量提升了212.0%。复配体系中,DP3-1显示了良好的力学性能,其弯曲强度和冲击强度分别提升了21.6%,71.8%。DP3-1的储能模量最大,抗蠕变性能最好,含有羧基的DPA和含有有机侧链及氨基的OA-POSS与WF和PP之间的协同作用,增强了WPC的力学性能。(3)保持DPA与OA-POSS最佳配比3:1不变,分别通过熔融共混法和喷淋法制备不同含量复配体系阻燃WPC(即RWPC和PWPC)。测试结果表明:阻燃剂含量增加,提高了RWPC和PWPC的热稳定性和阻燃性能。相同阻燃剂含量下,PWPC的热稳定性和阻燃性能更优异,燃烧后的炭层更完整坚固,这是由于PWPC中阻燃剂分布更加均匀,能更好的发挥阻燃效果。相同阻燃剂含量下,PWPC的力学性能和抗蠕变性能更好,因为PWPC的喷淋制备方法有效的避免了直接熔融共混时阻燃剂分布不均匀的问题,减少了因团聚缺陷对材料力学性能造成的不利影响。综上所述,DPA与OA-POSS以3:1的配比在WPC中发挥了P-Si协效阻燃的作用,同时其带有的极性官能团可与WF的羟基发生氢键作用以降低WF的极性,增强WF与PP的界面相容性。喷淋法可减少阻燃剂因分布不均团聚问题造成的力学下降,这为WPC在阻燃性能和力学性能提升方面提供了方向和思路。更多还原

【Abstract】 As a new type of green and environmentally friendly material,wood-plastic composites(WPC)have many advantages such as the unique woody feel of logs,good mechanical properties,and dimensional stability.It is widely used in transportation,construction industry,packaging and other fields.The wide application of WPC provides a development direction for recycling waste plastics and waste wood resources,which has a broad market and good development prospects.However,wood powder and most resins,the main components of WPC are flammable,which adversely affect the application of WPC,so it is critical to treat WPC with flame retardant.Traditional flame retardants usually have adversely affects on the mechanical properties of WPC.If the flame retardant properties and mechanical properties of WPC can be improved at the same time,the added value of WPC will be greatly enhanced and its application fields in life will be broadened.In view of the above problems,PP-based WPC with 60%wood flour was taken as the research object in this paper.Firstly,octaaminopropyl polyhedral oligomeric silsesquioxane(OA-POSS)was synthesized,and OA-POSS flame retardant WPC was prepared by melt blending and hot pressing.Secondly,in order to obtain WPC with better performance,9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)was modified to a derivative with carboxyl(DPA),and DPA and OA-POSS were compounded to flame retardant WPC.Finally,the properties of WPC prepared by different addition methods were explored.The effects of addition amount,compounding ratio and different adding methods of the flame retardants on the thermal stability,flame retardancy,static mechanical properties,dynamic mechanical properties and short-term creep properties of WPC were systematically studied.The main research contents and results are as follows:(1)OA-POSS was synthesized by hydrolysis and condensation of(3-Aminopropyl)triethoxysilane(KH-550).Thermogravimetric analysis showed that the residual carbon content of OA-POSS was 54.6%at 800 ~oC,which fully demonstrated the high temperature resistance of OA-POSS.OA-POSS flame retardant WPC was prepared by melt blending method.The results showed that the higher the OA-POSS content,the better the thermal stability and flame retardancy of WPC.When the OA-POSS content was 20%,the PHRR and THR of WPC decreased by 20.6%and 3.0%,respectively,and the residual carbon content increased by 260.9%.With the increase of OA-POSS content,the static mechanical properties of WPC increased first and then decreased.When the OA-POSS content was 15%,WPC achieved the best mechanical properties,and its bending strength and impact strength increased by 16.4%and 63.5%,respectively.The addition of OA-POSS improved the storage modulus and creep resistance of WPC,and reduced the tanδof WPC.This is due to the rigid particle of OA-POSS has good compatibility with PPs,which undertakes the reinforcement role in WPC and enhances the rigidity of the material.However,the high content of OA-POSS is easy to cause agglomeration in the melt blending process,thereby affecting the mechanical properties of WPC.(2)Under the condition of keeping the total content of flame retardant at 15%,DPA and OA-POSS compound flame retardant WPC was prepared by melt blending method.The results showed that DPA and OA-POSS had a good synergistic effect in WPC,and DP3-1(WPC with mass ratio of DPA to OA-POSS was 3:1)had the best thermal stability and flame retardancy.The PHRR and THR of DP3-1 decreased by 20.7%and 12.5%,respectively,and the carbon residue increased by 212.0%.The mechanical properties of DP3-1 were the best in the composite system,and the bending strength and impact strength were increased by 21.6%and 71.8%,respectively.DP3-1 had the largest storage modulus and the best creep resistance,which was due to the synergistic effect between DPA containing carboxyl and OA-POSS containing organic side chains and amino groups with WF and PP,which enhanced the mechanical properties of WPC.(3)Keeping the optimal ratio of DPA and OA-POSS at 3:1,the flame retardant WPC(RWPC and PWPC)with different contents were prepared by melt blending and spraying method,respectively.The results showed that the thermal stability and flame retardancy of RWPC and PWPC were better with the increase of flame retardant content.Under the same flame retardant content,the PWPC had better thermal stability and flame retardancy,and the carbon layer after combustion was more complete and solid,which was due to the more uniform distribution of flame retardants in PWPC,which could better play the flame retardant effect.Under the same flame retardant content,the mechanical properties and creep resistance of PWPC are better,because the spraying preparation method of PWPC effectively avoids the problem of uneven distribution of flame retardants in direct melt blending,and avoids the influence of agglomeration defects on the mechanical properties of materials.In summary,DPA and OA-POSS at a ratio of 3:1 played the role of P-Si synergistic flame retardant effect in WPC.At the same time,its polar functional groups could produce hydrogen bond with the hydroxyl group of WF to reduce the polarity of WF and enhanced the interfacial compatibility between WF and PP.Spraying method could reduce the mechanical decline caused by uneven distribution and agglomeration of flame retardants,which provided an idea for the improvement of flame retardancy and mechanical properties of WPC.更多还原