【作者】 姜广明；

【导师】 赵素合；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2010， 博士

【摘要】 废旧橡胶是重要的可再生资源,生物脱硫是一种新型的废橡胶再生的方法。本论文涉及使用四种脱硫微生物：氧化亚铁硫杆菌,硫杆菌,鞘氨醇单胞菌和脂环酸芽孢杆菌,对硫黄硫化的天然橡胶胶粉和丁苯橡胶胶粉进行生物脱硫。通过全面地研究温度、酸碱度、搅拌速度和培养基成分等因素对脱硫微生物生长的影响,确定了四种脱硫微生物最佳的培养条件。对脱硫天然橡胶和丁苯橡胶进行了表面化学基团分析、元素含量和结合状态分析,初步地探讨了脱硫微生物对胶粉进行生物脱硫的可能途径以及各种脱硫微生物的脱硫机理的异同。表征并且比较了脱硫胶粉与生胶共混的硫化胶的交联密度,力学性能,应力应变性能,动态力学性能,拉伸断面及撕裂断面形貌和断面上胶粉粒子的形态等,证明了生物脱硫方法改善了脱硫胶粉在基体橡胶中的分散性,增强了脱硫胶粉与基体橡胶的界面结合性,提高了脱硫胶粉填充的硫化胶的力学性能。1.筛选了脱硫活性较高的氧化亚铁硫杆菌新菌株YT-1,研究其在含有不同浓度的亚铁离子的改性9K培养基中的生长速度和生物量,确定了脱硫时适宜的培养基成分。通过对脱硫天然橡胶和丁苯橡胶的红外光谱(FTIR)和X射线光电子能谱(XPS)分析,以及检测胶粉脱硫时培养液中的硫酸根浓度的变化,证明了氧化亚铁硫杆菌对硫黄硫化的天然橡胶和丁苯橡胶的脱硫机理符合硫杆菌生物脱硫时常见的“4S途径”。脱硫天然胶粉的交联密度下降,交联网络结构受到破坏。填充脱硫天然胶粉的硫化胶的力学性能和动态力学性能提高,说明脱硫胶粉和基体橡胶之间的界面结合改善。用乙醇对天然胶粉灭菌明显提高了氧化亚铁硫杆菌对天然胶粉的脱硫效果。兼性异养的氧化亚铁硫杆菌新菌株YT-1的脱硫效果优于严格自养的氧化亚铁硫杆菌菌株T-1。2.筛选了多株硫杆菌菌株HB122、HB062和X4等,并测试了天然胶粉和丁苯胶粉的加入量对硫杆菌的生物量的影响,确定了脱硫时适宜加入的胶粉量。FTIR和XPS分析以及Schiff试剂染色实验证实了硫杆菌HB122不仅断裂了硫化橡胶中的的硫磺交联键,还能够氧化碳碳双键,生成醛基。硫杆菌HB122对天然胶粉的脱硫效果优于其他2个硫杆菌菌株。脱硫天然胶粉填充的硫化胶的拉伸强度和断裂伸长率都有明显的提高。填充脱硫15天的天然胶粉的硫化胶的力学性能比填充脱硫30天的天然胶粉的硫化胶高。填充脱硫丁苯胶粉的硫化胶的力学性能提高较小,说明硫杆菌对丁苯胶粉的脱硫效果不显著。3.筛选了一株鞘氨醇单胞菌PL1,考察了天然胶粉和丁苯胶粉的加入量对其生物量的影响,确定了脱硫时胶粉的适宜加入量。FTIR和XPS的结果证明了脱硫天然橡胶表面出现了S=O和C=O基团；脱硫丁苯橡胶表面的C=C含量下降。这说明鞘氨醇单胞菌既能氧化橡胶主链的C=C双键,生成羧基；又能氧化断裂硫磺交联键,产生亚砜、砜以及磺酸基团。填充脱硫丁苯胶粉的天然硫化胶的拉伸强度和断裂伸长率都提高。同样地,填充脱硫丁苯胶粉的丁苯硫化胶的拉伸强度和断裂伸长率也有明显的提高。填充脱硫丁苯胶粉的硫化胶的动态力学性能和扫描电镜分析,证实了脱硫丁苯胶粉与基体橡胶的界面结合较好。由于界面结合的增强,填充脱硫丁苯胶粉的硫化胶的耐磨性也有明显的提高。4.筛选出了一株嗜热的脂环酸芽孢杆菌菌株YS-9。脱硫橡胶的FTIR表明脂环酸芽孢杆菌能氧化硫磺交联键,而不会破坏天然橡胶和丁苯橡胶的C-C键和C=C双键。XPS的结果证明了脱硫橡胶的碳元素没有发生氧化反应,交联键被氧化导致了硫元素含量降低,氧元素含量升高。填充脱硫天然胶粉的丁苯硫化胶的交联密度降低,拉伸强度和断裂伸长率明增加。同样的,填充脱硫丁苯胶粉的丁苯硫化胶的交联密度下降,拉伸强度和断裂伸长率提高,耐磨性能提高。动态力学性能和SEM分析表明脱硫天然胶粉和丁苯胶粉与基体丁苯橡胶的相容性较好,两者之间形成了较强的界面作用。更多还原

【Abstract】 Waste rubber is an important renewable resource, and microbial desulfurization is a novel reclaiming method of waste rubber. This paper involved microbial desulfurization for ground rubber (natural rubber and styrene butadiene rubber) with four bacteria with sulfur desulfurization ability: Thiobacillus ferrooxidans, Thiobacillus, Sphingonomas, and Alicyclobacillus.The optimal culture conditions for each bacterium were fully researched, such as temperature, pH value, stirring speed, culture medium and nutrition compositions. The possible microbial desulfurization pathways for sulfur vulcanized natural rubber and styrene butadiene rubber were discussed. The similarities and differences between desulfurization mechanism of various kinds of bacteria were compared through surface analysis of elements structure and contents. When desulfurized ground rubber was incorporated with virgin rubber, crosslink densities, mechanical properties, stress-strain properties, dynamic mechanical properties, the morphologies of tensile and tear fracture surfaces of filled vulcanizates and the situation of ground rubber particles on the fracture surfaces were studied.All these results proved that microbial desulfurization technology improved the dispersion of desulfurized ground rubber in rubber matrix, and also strengthed interphase bonding forces between dispersion ground rubber phases and rubber matrix, and therefore increased the mechanical properties of filled rubber vulcanizates.The major work of this paper is as follows: 1. Two Thiobacillus ferrooxidans strains with high desulfurization ability were selected:Thiobacillus ferrooxidans YT-1 and Thiobacillus ferrooxidans T-1. The biomasses in different culture mediums were studied, and then several modified 9K mediums were determined as desulfurization culture medium. FTIR and XPS measurements were tested for desulfurized NR and SBR vulcanizates, and sulfate concentration in desulfurization medium was monitored. All results supported that desulfurization mechanism of Thiobacillus ferrooxidans for NR and SBR matched the 4S pathway. The crosslink density of desulfurized NR ground rubber decreased after desulfurization. NR and SBR vulcanizates filled with desulfurized NR ground rubber showed good mechanical properties and dynamic mechanical properties, and the interphase bonding forces were improved. Disinfection of NR ground rubber by ethanol was proved to be very important for microbial desulfurization. Compared with strictly autotrophic Thiobacillus ferrooxidans T-1, facultative heterotrophic Thiobacillus ferrooxidans YT-1 was more effective for microbial desulfurization of NR ground rubber.2. Several Thiobacillus strains were screened. The influences of ground rubber to the growth of Thiobacillus sp. HB122 were characterized in order to obtain the proper loading of ground rubber. FTIR, XPS analysis and Schiff agent staining experiments proved that Thiobacillus sp. HB122 not only disrupted the sulfur crosslink bonds of NR and SBR vulcanizates, but also oxidized the carbon-carbon double bonds of polymers to aldehyde groups. The desulfurization effect of Thiobacillus sp. HB122 for NR ground rubber was better than that of Thiobacillus sp. HB062 and Thiobacillus sp. X4. Tensile strength and enlongation at break of vulcanizates filled with desulfurized NR ground rubber improved obviously. After desulfurized for 15 days, the mechanical properties of vulcanizates filled with desulfurized NR ground rubber were better than that filled with desulfurized ground rubber for 30 days. Desulfurized SBR ground rubber rarely increased the mechanical properties of filled vulcanizates, which indicated that the desulfurization effect of Thiobacillus sp. HB122 was not very good for SBR vulcanizates.3. A new Sphingomonas species strain was cultured. And the growth of it with different amounts of NR ground rubber and SBR ground rubber was investigated, and then the contents of ground rubber was obtained when desulfurization was processing. The evidences of S=O and C=O on the surface of desulfurized vulcanizates were shown in FTIR spectra. XPS spectra found that C=C double bonds decreased for desulfurized vulcanizates. Therefore, Sphingomonas oxidized the carbon-carbon double bonds of rubber main chains to carboxyl group. And it also oxidized the sulfur bonds and sulfur-carbon bonds to sulfoxide, sulfone and sulfonic acid groups. Tensile strength and elongation at break of NR vulcanizates filled with desulfurized SBR ground rubber were improved. So were SBR vulcanizates filled with desulfurized SBR ground rubber. Dynamic mechanical properties and SEM morphologies of vulcanizates filled with desulfurized SBR ground rubber proved the better interphase bonding between ground rubber and rubber matrix. Because of the stronger interphase bonding, the abrasion resistances of filled vulcanizates were also improved.4. A novel thermophilic Alicyclobacillus species bacterium was obtained. FTIR spectra reflected that Alicyclobacillus did not change carbon-carbon bonds or carbon-carbon double bonds of NR and SBR vulcanizates. XPS analysis of desulfurized rubber also found that carbon element was not oxidized, but sulfur element content decreased and oxygen element content increased due to the oxidantion of sulfur crosslink bonds. Crosslink density of filled vulcanizes decreased if compared with untreated ground rubber. Tensile strength and elongation at break of SBR vulcanizates filled with desulfurized NR ground rubber increased. So were SBR vulcanizates filled with desulfurized SBR ground rubber. The abrasion resistances of SBR vulcanizates filled with desulfurized SBR ground rubber also improved. Dynamic mechanical properties and SEM morphologies proved that vulcanizates filled with desulfurized NR and SBR ground rubber exhibited a better interphase bonding.更多还原