Reinforcement of Styrene-Butadiene Rubber with Silica Modified by Silane Coupling Agents: Experimental and Theoretical Chemistry Study

The properties of styrene-butadiene rubber (SBR) reinforced by modified silica was investigated according to national standards. Silica was modified by silane coupling agents KH-570, KH-590, and KH-792. The optimized geome-tries of molecular modified silica reinforced SBR were obtained by using B3LYP calculation of density functional theory with the 6-31+G basis sets. The natural bond orbital analyses were carried out. The Si—O bond length of silica modified by KH-792 was the shortest and the electronegative of O was the highest. It indicated that the connection between silica and KH-792 was the tightest. Higher tensile strength and elongation of reinforced SBR was obtained by silica modified with the KH-792. It was caused by large delocalization of lone pair electrons of the two N atoms in KH-792. The S—C bond length in silica modified by KH-590 was longer than the ordinary S—C bond length. Then the sulfur free radical (·S·) was produced more easily in vulcanization. The degree of crosslink was increased by the cross-linkage of the rubber molecule and the sulfur free radical. That was why the highest stress and tear strength of reinforced SBR was produced when silane coupling agent KH-590 was used. The calculation results was in accord with experimental data.

Pyrolysis of vulcanized styrene-butadiene rubber via ReaxFF molecular dynamics simulation

Styrene-butadiene rubber(SBR)is widely used in tires in the automotive segment and vulcanization using sulfur is a common process to enhance its mechanical properties.However,the addition of sulfur as the cross-linking agent usually results in impurities in pyrolysis products during rubber recycling,and thus the desulfurization during tire pyrolysis attracts much attention.In this work,the pyrolysis of vulcanized SBR is studied in detail with the help of Reax FF molecular dynamics simulation.A series of crosslinked SBR models were built with different sulfur contents and densities.The following Reax FF MD simulations were performed to show products distributions at different pyrolysis conditions.The simulation results show that sulfur products distribution is mainly controlled by sulfur contents and temperatures.The reaction mechanism is proposed based on the analysis of sulfur products conversion pathway,where most sulfur atoms are bonded with hydrocarbon radicals and the rest transfer to H_(2)S.High sulfur contents tend to the formation of elemental sulfur intermediate,and temperature increase facilitates the release of H_(2)S.

MORPHOLOGY,INTERFACIAL INTERACTION AND PROPERTIES OF STYRENE-BUTADIENE RUBBER/MODIFIED HALLOYSITE NANOTUBE NANOCOMPOSITES

A natural nanotubular material,halloysite nanotubes(HNTs),was introduced to prepare styrene-butadiene rubber/modified halloysite nanotube(SBR/m-HNT) nanocomposites.Complex of resorcinol and hexamethylenetetramine (RH) was used as the interfacial modifier.The structure,morphology and mechanical properties of SBR/m-HNT nanocomposites,especially the interfacial interactions,were investigated.SEM and TEM observations showed that RH can not only facilitate the dispersion and orientation of HNTs in SBR matrix at ...

Strengthening and toughening styrene-butadiene rubber by mechanically interlocked cross-links

Styrene-butadiene rubber(SBR)is an indispensable material in modern society,and the necessity for enhanced mechanical properties in SBR persists,particularly to withstand the rigors of challenging environmental conditions.To surmount the limitations of conventional cross-linking modes,mechanical bonds stabilized by host-guest recognition are incorporated as the cross-linking points of SBR to form mechanically interlocked networks(MINs).Compared with covalently cross-linked network,the representative MIN exhibits superior mechanical performance in terms of elongation(1392%)and breaking strength(4.6 MPa),whose toughness has surged by 17 times.Dissociation of host-guest recognition and subsequent sliding motion provide an effective energy dissipation mechanism,and the release of hidden length is also beneficial to enhance toughness.Furthermore,the introduction of the rotaxane cross-links made the network more pliable and possess damping and elastic properties,which can return to initial state with one minute rest interval.We aspire that this direct introduction method can serve as a blueprint,offering valuable insights for the enhancement of mechanical properties in conventional commercial polymer materials.

Improving Thermal-oxidative Aging Resistance of Styrene-butadiene Rubber by Antioxidant Loaded Silica Aerogel

The antioxidant N-isopropyl-N'-phenyl-p-phenylenediamine(4010NA)was dissolved in ethanol and impregnated into silica aerogel(SAG)via vacuum-pressure cycles,yielding composite particles(A-N)with enhanced sustained-release and reinforcing capabilities.The effect of A-N on the mechanical properties and thermal-oxidative aging resistance of styrene-butadiene rubber(SBR)vulcanizates was investigated.TGA and BET assessments indicated that the loading efficiency of 4010NA in SAG reached 14.26%within ethanol's solu bility limit.Incorporating A-N into SBR vulcanizates significantly elevated tensile strength by 17.5%and elongation at break by 41.9%over those with fumed silica and free4010NA.Furthermore,A-N notably enhanced the thermal-oxidative aging resistance of SBR.After aging for 96 h at 100℃,the tensile strength and elongation at break of SBR with A-N sustained 70.09%and 58.61%of their initial values,respectively,with the retention rate of elongation at break being 62.8%higher than that of SBR with fumed silica and free antioxidant.The study revealed that A-N composite particles significantly inhibited the crosslinking in SBR's molecular chains,reducing hardening and embrittlement during later thermal-oxidative aging stages.

天然橡胶加工废水发酵及资源化利用初步研究

天然橡胶加工废水处理、排放是天然橡胶加工产业亟待解决的实际问题,探究不同菌剂对天然橡胶加工废水的发酵效果并将其资源化利用,具有较高的生产应用价值。设置不添加菌剂、添加芽孢杆菌、放线菌、黑曲霉菌4种不同的处理对天然橡胶废水进行好氧发酵,并以清水和复合肥作为对照,进行盆栽试验研究不同发酵液对小白菜生长、品质及土壤理化性质的影响。结果表明:添加黑曲霉菌发酵效果最优,其次为芽孢杆菌、放线菌发酵处理;不同处理的发酵液灌溉对小白菜的生长品质均有较好的提升作用,其中添加黑曲霉菌、放线菌发酵处理提升效果最优,其次为添加芽孢杆菌处理;添加菌剂各处理对土壤孔隙度有提升趋势,且平均值高于清水对照(1.76%),其中添加黑曲霉菌发酵液对土壤孔隙度提升最高。与清水对照相比,添加黑曲霉菌发酵液灌溉后土壤pH、有机质含量分别提高了0.33%、19.21%。综上,添加黑曲霉菌处理对小白菜生长品质提升效果最优且对土壤孔隙度不造成影响。

橡胶企业生化尾水深度处理剂的研制与评价

本文采用2499型PVA、HEDP、聚合氯化铝、KMnO_(4)为原料制备橡胶企业生化尾水深度处理剂;通过单因素实验筛选出最佳氧化剂类型与加量;设计两组正交实验,优化出最佳反应条件并筛选出最佳反应物配比。实验结果表明,以COD为考察因素,制备处理剂的最佳反应条件为反应温度为60℃、反应时间为5h、体系p H值为7、机械搅拌速度为600r·min^(-1);以COD、SS、BOD以及NH_(3)-N为考察因素,优化出KMnO_(4)为最佳氧化剂,最优加量为9%;反应物的最佳配比为14%PVA+10%聚合氯化铝+10%HEDP+9%KMnO_(4);参照GB 27632-2011《橡胶制品工业污染物排放标准》优化出处理剂最佳加量为150 mg·L^(-1),动态连续处理工艺中最佳的进液流量应为100 L·h^(-1)。

不同碱催化剂对臭氧碱催化氧化过程中去除·OH抑制剂的试验研究

分别选用氢氧化钙、氢氧化钠作为臭氧碱催化氧化过程的催化剂,通过对比臭氧碱催化氧化丁苯橡胶废水过程中COD和TOC的变化,考察不同碱去除水中·OH抑制剂的效果。结果表明,在丁苯橡胶废水300 mL、臭氧质量浓度45.0 mg/L、臭氧气速0.5 L/min和相同反应时间条件下,用氢氧化钙的COD去除率明显高于用氢氧化钠的;用氢氧根离子浓度等量的2 g/L氢氧化钠和1.86 g/L氢氧化钙分别催化臭氧氧化时间超过30 min后,废水中TOC含量顺序为:氢氧化钙催化<氢氧化钠催化后再用Ca^(2+)沉淀<氢氧化钠催化,超过45 min后,前者TOC远小于后二者TOC。用氢氧化钙催化臭氧氧化丁苯橡胶废水,Ca^(2+)不仅能够起到去除部分有机物的作用,更主要的是起到去除反应产生的·OH抑制剂(碳酸根)的作用,使反应更彻底,提高了臭氧的利用率。

天然橡胶加工废水中异养硝化好氧反硝化菌株的筛选及脱氮特性

从天然橡胶加工废水中分离筛选出一株异养硝化好氧反硝化菌株JD-7,再根据16S rDNA序列和形态学特征初步鉴定该菌株为芽孢杆菌属。菌株JD-7在48 h内能将水体中氨态氮质量浓度从最初的98.24 mg/L降到8.33 mg/L,去除率达到91.52%,并且菌株同时具有去除硝态氮和亚硝态氮的能力,去除率分别达到44.39%和50.06%。通过响应面实验方法探究菌株不同影响因子(温度、初始pH值、碳氮比)下脱氮能力。结果显示,在温度为30.35℃、初始pH值为7.85、碳氮比为6.13的条件下,脱氮能力最强。将菌株投入到不同比例的实际废水进行小试实验确定菌株的实际应用效果,在最优条件下JD-7对实际天然橡胶加工废水的氨氮去除速率可达到131.48 mg/(L·d)。研究表明,菌株JD-7具有较高的脱氮能力,在天然橡胶加工废水处理中具有巨大的应用潜力。

电渗析技术处理橡胶促进剂废水研究

采用电渗析技术处理橡胶促进剂废水并进行盐和有机物分离研究,探究淡浓室体积比、淡室进水电导、电压、流量和温度等因素对电渗析分离效果和操作性能的影响。实验结果表明,增大淡室进水电导、电压、流量和温度,均可以提高传质速率,其中电压和温度对传质速率的影响较为明显。增大淡室进水电导、流量、温度,减小电压,可以提高电流效率、降低能耗。在实验条件下,淡室废水电导率降低到10 mS·cm^(-1)以下,淡室COD含量为4 940 mg·L^(-1),有效实现了盐和有机物的分离,满足了生化处理要求,为橡胶促进剂废水处理提供了新的思路。

石油化工污水处理技术的研究分析

石油化工产品生产过中产生大量的生产污水,且组分复杂,处理难度很大,特别橡胶废水更是当前石化行业难处理的生产废水之一。某石油化工企业污水处场的运行存在诸多问题,污水COD、磷、氨氮严重超出排放标准指标,对这些问题进行分析研究,并针对问题制定了解决技术改造方案,通过芬顿催化氧化和混凝沉淀的预处理手段降低了橡胶废水磷含量,去除了部分有机物并改善其可生化性,提高后续污水处理装置生物处理的效率,使污水处理场可以稳定运行,实现了污水COD、磷、氨氮等达标排放,并提高了污水回用率。

石化废水溶解性有机物的组成特征及生物毒性

分析了石化综合污水处理系统的运行情况,考察了丁苯橡胶废水的污染物组成与生物毒性对生产废水、气浮出水的影响。结果表明,在各类生产废水中,丁苯橡胶废水含盐、含N、含P且富含芳香类有机物,是导致生化处理单元受冲击、出水超标的主要原因;在生产废水、丁苯橡胶废水和气浮出水的溶解性有机物(DOM)中,亲水性有机物(HiM)的DOC占比分别为82%、60%和51%,疏水性有机物的DOC占比分别为18%、40%和49%。表征结果显示,丁苯橡胶废水与气浮出水中DOM的特征峰相似,主要污染物质同源。急性毒性分析结果表明,疏水中性有机物(HoN)的毒性最强,疏水酸性有机物(HoA)次之。建议对丁苯橡胶废水进行单独预处理,从源头上消减有毒物质的含量,减轻对后续生化单元的冲击。

高盐高COD橡胶助剂生产废水的处理工艺及研究进展

概述高盐高化学需氧量(COD)橡胶助剂生产废水的处理工艺及研究进展。分析常用的废水处理工艺如Fenton氧化法、微电解法、生化法、混凝沉淀法、吸附法、离子交换法、蒸发法、冷冻结晶法和膜分离法的优缺点,介绍废水处理工艺研究进展。高盐高COD废水处理工艺的研究方向将集中在新材料及物化与生化组合工艺,尽可能地提高废水中盐含量和COD等的去除率,同时降低处理成本。

Insights into the Payne Effect of Carbon Black Filled Styrene-butadiene Rubber Compounds

As a widely used reinforcing filler of rubber, carbon black(CB) often enhances the nonlinear Payne effect and its mechanism still remains controversial. We adopt simultaneous measurement of rheological and electrical behaviors for styrene-butadiene rubber(SBR)/CB compounds and CB gel(CBG) during large deformation/recovery to investigate the contribution of conductive CB network evolution to the Payne effect of the compounds. In the highly filled compounds, the frequency dependence of their strain softening behavior is much more remarkable than that of their CB network breakdown during loading, while during unloading the unrecoverable filler network hardly affects the complete recovery of modulus, both revealing that their Payne effect should be dominated by the disentanglement of SBR matrix. Furthermore,the bound rubber adjacent to CB particles can accelerate the reconstruction of continuous CB network and improve the reversibility of Payne effect. This may provide new insights into the effect of filler network, bound rubber, and free rubber on the Payne effect of CB filled SBR compounds.

New Fabrication and Mechanical Properties of Styrene-Butadiene Rubber/Carbon Nanotubes Nanocomposite

A novel technology to prepare styrene-butadiene rubber （SBR）/carbon nanotubes （CNTs） composites was developed by combining a spray drying method and a subsequent mechanical mixing process. The cross-linking degrees of the vulcanized composites increased gradually with the additive CNTs contents. By comparing with those of the pure SBR composites, the mechanical properties such as tensile strength, tear strength and hardness of the composites filled with CNTs at certain contents were dramatically improved almost by 600%, 250% and 70%, respectively. The fabrication of the CNTs filled with SBR composites by combination of the spray drying method and subsequent mechanical mixing process was effective for enhancing the reinforcement effects of CNTs in rubbers. The novel technology can also open a new route for the modification and reinforcement on the nanocomposites with large amount of CNTs.

胶乳凝固方法对生胶中非胶元素留存与流失的影响

以鲜胶乳直接加热烘干为对照,对比不同凝固方法(酸凝固、糖凝固、盐凝固、自然凝固)对生胶制备过程中非胶元素留存的影响,分析了其在生胶制备过程中的流失情况。结果表明,与胶乳直接加热烘干相比,不同凝固方法制备的生胶中氮、磷、钾、钙、镁、铁、锰、铜和锌含量分别降低了23.0%~58.3%、70.3%~89.8%、93.4%~99.1%、14.2%~48.3%、70.7%~97.7%、31.4%~64.4%、24.7%~58.2%、14.6%~84.3%和18.2%~75.0%。其中自然凝固、糖凝固和盐凝固生胶氮含量和铜含量显著低于酸凝固,镁含量和锌含量显著高于酸凝固;但生胶钾含量在4种凝固方法下无显著差异。在生胶制备过程中,清洗、压片等过程造成胶乳中的磷(≥73%)、钾(≥95%)、镁(≥74%)随乳清废水流失,氮、钙、铁、锰、铜和锌流失比例稍低,为19%~86%。相关分析表明,留存在生胶中的非胶元素含量(锰除外)、制胶过程中流失的非胶元素含量与胶乳自身的非胶元素含量呈显著或极显著正相关。建议在实际生产中选择合适的凝固方法,以保证最优的天然橡胶性能和最大化利用乳清废水中的非胶元素。

橡胶助剂生产废水预处理工艺优化途径

随着社会经济飞速发展,涌现了越来越多的橡胶助剂生产企业。企业在实际的生产过程中,会产生大量的废水,且这些废水里面还含有高盐以及其他复杂的成分。如果直接排放,不对其加以有效处理,则不仅会污染生态环境,甚至还会威胁到周边居民的身体健康。然而,传统的废水预处理工艺已经远远达不到当前的应用需求,必须要相关人员对其进行优化创新,针对橡胶助剂生产废水的特点,提出改进策略,进而达到节能环保的目的。本文就橡胶助剂生产废水的预处理工艺展开探讨。

橡胶助剂CBS生产废水处理工程实例

橡胶助剂CBS生产废水具有有机物浓度高、可生化性差的特点,某工程设计采用铁碳微电解-芬顿氧化-ABR厌氧-A/O-混凝沉淀-过滤组合工艺,介绍了工艺流程、设计和运行参数。运行结果表明,该组合工艺处理效果显著,出水COD、BOD5、NH3-N、SS的质量浓度分别达到140、25、5、50 mg/L以下,主要出水指标可达到GB 8978—1996《污水综合排放标准》二级标准。

天然硼矿石负载铁锰氧化物的合成及应用研究

采用溶胶凝胶法制备天然硼矿石负载Fe-Mn氧化物的Fe-Mn-B复合纳米微孔催化剂,通过X射线衍射(XRD)、扫描电镜(SEM)及能谱对催化剂的物相结构进行表征;并考察该复合纳米催化剂作为非均相芬顿催化剂深度处理丁腈橡胶废水的性能。结果表明,在初始pH值5,双氧水加药量0.8 mL/L,催化剂加药量5 g/L,反应时间30 min后,处理液COD值小于70 mg/L,COD去除率69.7%,出水指标满足GB 27632—2011《橡胶制品工业污染物排放标准》的直接排放标准。

某橡胶厂污水预处理系统运行分析及改造方案

某合成橡胶厂丁苯橡胶污水预处理系统采用了混凝+絮凝+斜板沉淀+气浮的处理工艺。通过对一年的水质及运行现状进行分析,发现系统存在易受高浓度COD及悬浮物负荷冲击、自动化程度偏低、处理规模偏小的问题,已逐渐无法满足使用需求及未来发展。针对相关问题提出了在系统末端分别增设Fenton高级氧化单元和砂滤单元的解决方案,预计可取得较好的处理效果。针对处理系统自动化程度偏低这一问题,对污水处理厂智能化改造进行讨论。在出水前增设有自动控制的监测排放单元和事故单元,可有效提升处理系统工艺调节的时效性,减少人力资源浪费,出水水质的稳定性也得到保证。