【作者】 王杰；

【导师】 张建春；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2011， 博士

【摘要】 近年来,天然纤维生物质作为高分子材料的填料受到较大关注。随着汉麻纤维在纺织工业上的应用,我国许多地方开始重视对汉麻的种植。传统汉麻利用主要集中在外层韧皮纤维上,而占汉麻纤维产量70-80%的汉麻秆芯,通常被当做燃料焚烧或直接作为农业废物而填埋掉。这样,在本论文中,提出了将经过粉碎处理的汉麻秆芯粉(HP)用作橡胶的填料,研究其对填充橡胶结构与性能的影响,以及与常用的白炭黑、尼龙和芳纶短纤维并用填充后橡胶结构和性能的变化,以探讨将其用于橡胶工业的可行性。这对实现汉麻资源的有效综合利用、减少垃圾排放和环境污染等方面具有重要意义,对于目前我国提出的建设资源性社会和低碳经济发展起到重要推动作用。首先,研究对比了传统的改性工艺固体粘合剂改性、RFL浸渍体系、偶联剂改性对汉麻秆芯粉填充的丁苯橡胶(SBR)性能影响。结果发现,偶联剂改性工艺简单、能够有效提高HP在橡胶中的分散能力,改善填充橡胶的加工性能和力学性能。偶联剂双[3-(三乙氧基硅基)丙基]四硫化物(Si69)通过分子中双官能团与橡胶大分子链和HP表面发生化学作用,有效的提高了填料-基质间的界面作用,对HP的改性效果优于偶联剂γ-氨丙基三乙氧基硅烷(KH550)的。在Si69最佳用量3%的条件下,通过高混机对HP进行改性,系统地研究了HP填充对丁苯橡胶硫化特性、加工性能、微观结构以及力学性能、拉伸行为和动态力学性能的影响。在不超过60phr填充量下,HP用量增长有利于橡胶复合材料硬度、模量和拉伸力学性能的提高。Si69改性增强了HP填充橡胶的硫化特性,改善了混炼胶的加工性能,填充橡胶复合材料的定伸应力、硬度和撕裂强度、拉伸强度等力学性能明显改善,动态力学性能、耐水性明显提高。在HP与白炭黑并用填充研究中,考察了并用比改变对填充丁苯橡胶和三元乙丙橡胶加工性能、微观结构、力学性能以及动态力学性能的影响。认为在20phr白炭黑填充量下,当HP的用量不超过30phr时,在大幅提高白炭黑填充橡胶复合材料模量、硬度、撕裂强度和动态力学性能的同时,对橡胶的拉伸性能也有改善作用,并用填充的橡胶复合材料展示了更好的硬度和韧性。过量的HP填充会对白炭黑与橡胶基质作用产生较大不利影响,橡胶复合材料硬度和模量提高的同时,断裂伸长率和拉伸强度急剧下降。在传统的乳液-共沉改性基础上,通过引入少量的KH550改性粘土和亲水性丁苯吡胶乳,明显降低了HP在絮凝共沉中的团聚,提高了HP与丁苯橡胶间的界面相互作用,制备出了改性效果较好的HP母胶。通过系统对比乳液-共沉改性和Si69熔体直接改性两种改性方法对HP/粘土/SBR橡胶复合材料微观结构和性能的影响,认为利用乳液-共沉改性可有效发挥HP和粘土对橡胶增强的协同作用,获得的复合材料中HP和粘土分散较好,与橡胶基质间界面作用明显改善,填充橡胶的力学性能、动态力学性能和耐疲劳性能明显提高。并在此基础上,研究了乳液改性HP与白炭黑并用对橡胶结构和性能的影响。当HP不超过20phr填充量时,橡胶复合材料展示了优异的理化性能。考察了少量尼龙、芳纶短纤维与HP并用填充对丁苯橡胶结构和性能的影响。研究了短纤维长度、特性、填充量以及HP的不同改性处理对并用填充后橡胶结构和性能的影响。结果表明,乳液-共沉改性HP与2phr的1mm短纤维并用填充,硫化胶的各项理化性能最好。为了改善HP填充丁苯橡胶的加工性能和力学性能,研究了并用天然橡胶(NR)对其相关性能的影响。天然橡胶并用在明显改善加工性能、硫化特性和拉伸力学性能的同时,使HP填充丁苯橡胶的硬度和定伸应力有所下降。通过对不同改性HP填充SBR/NR橡胶结构与性能研究,认为乳液-共沉改性效果优于Si69高混机改性的,在HP填充量为30phr下,橡胶复合材料的综合力学性能达到最好。更多还原

【Abstract】 In recent years, natural fibers as the fillers of polymer have been paid more attention. With the application of hemp fiber in the textile industries, hemp plantation has been focused on in some areas of China. Traditionally, the utilization of hemp fiber focuses on the bast, on the contrary, the hemp hurd accounting for 70-80wt% of hemp stem was disposed by combustion or landfill. Therefore, in this paper, the hemp hurd powder (HP) as rubber filler was studied in order to investigate its effect on the structure and performances of the rubber. At the same time, the mixed use of HP and silica, the mixed use of HP and nylon, as well as the mixed use of HP and aramid were also filled in the rubber and the effect on the structure and physical properties of filled rubber composites was also investigated. It is beneficial to realize the comprehensive utilization of hemp resource, reduce the agro-waste accumulation and environmental pollution. It would play a positive role in the construction of resource society and low carbon economic development. Firstly, the comparations and effects of different treatment methods containing phenol formaldehyde-hexamethylene tetramine bonding system, RFL bonding system, and the coupling agent treatment on the properties of HP filled styrene-butadiene rubber (SBR) were researched. Among these methods, coupling agent modification appeared as a quick and effective method to provide good interfacial adhesion and HP dispersion in the rubber matrix. Bis-(3-triethoxysilylpropyl) tetrasulfide (Si69) with bi-functional groups could produce chemical bonding between SBR and the hemp fiber, and improved effectively HP-SBR interfacial interaction. Therefore, Si69 treatment is superior to that of the y-aminopropyl triethoxysilane (KH550) in terms of the properties of SBR/HP composites. With the optimum Si69 dosage of 3 wt% of HP through the modification in the mixer, the curing characteristics, the proccessability, mechanical properties, and dynamical mechanical properties of HP filled SBR were systematically investigated. When the loading is no more than 60phr, the addition of HP would improve the hardness, modulus, and tensile properties of SBR composites. Si69 treatment could shorten the curing process and improve the proccessability. Moreover, the mechanical properties such as hardness, modulus, tensile and tear strengths, dynamical mechanical properties, and water resistance of SBR composites also considerably increased.Secondly, the combination effects of HP and silica on the proccessability, microstructure, mechanical properties, and dynamic mechanical properties of SBR and ethylene-propylene-diene rubber (EPDM) composites were investigated. At 20phr silica, when the loading of HP was no more than 30phr, the rubber composites showed the better combination of stiffness and toughness. The addition of HP obviously improved the modulus, hardness, and tear strength of rubber composites filled with silica, simultaneously had a positive impact on tensile mechanical properties. The excessive HP content was helpful to the improvement of modulus and hardness of rubber composites, however, and led to the sharp decrease of elongation at break and tensile strength due to the deterioration of silica-matrix interfacial interaction.Based on traditional latex coagulation treatment, SBR/HP composite was successfully prepared. The addition of small portion of KH550 modified clay and styrene-butadiene-vinyl pyridine latex in suspension could obviously decrease the HP agglomeration during coagulation and improve the HP-SBR matrix interfacial bonding. The effects of microstructure and physical properties of HP/clay/SBR composites on different modified methods such as latex coagulation and Si69 melt organic modification were systematically studied. After the latex coagulation treatment, due to the synergistic reinforcement of HP and clay, the composites showed better fillers dispersion in matrix and stronger filler-matrix interfacial bonding, more superior mechanical properties, dynamic mechanical properties and fatigue resistance. At the same time, the combination effects of latex coagulation modified HP and silica on the structure and properties of SBR composites were investigated. When HP loading was no more than 20phr, the filled rubber composites showed superior physical properties.The effects of mixed use of small portion of nylon, aramid and HP on the structure and properties of SBR composites were explored. The effects of length, feature, and loading of synthetic fibers, as well as different HP modifications on the structure and properties of SBR composites were studied. The composites filled with short fibers with 1mm length and latex coagulation treated HP showed the optimal physical properties.In order to improve the proccessability and mechanical properties of SBR, the related performance of filled SBR/NR blends was investigated. The introduction of NR could obviously improve the proccessability, curing process, and tensile properties of SBR composites, and resulted in the decrease of hardness and modulus. Comparing the structure and properties of SBR/NR composites filled with different pretreatment HP, the results revealed latex coagulation treatment was superior to the coupling agent treatment during the mixer. Under this circumstance, the composites with 30phr HP content showed the optimal physical properties.更多还原