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.

Effect of UV radiation aging on creepage discharge characteristics of high temperature vulcanized silicon rubber at high altitude

The physicochemical properties and creepage discharge characteristics of aged high temperature Vulca nized(HTV)silicone rubber materials were investigated by ultraviolet radiati on(UV)aging method in this study.The experimental results show that as the aging time increases,the creepage discharge flashover voltage increases first and then decreases.But the aging time has little effect on the creepage discharge inception voltage.With the aging time prolonged,the discharge endurance time of HTV silicone rubber is shortened,and the creepage discharge development velocity is accelerated.In the short time of applying voltage to aging material,the magnitude of discharge in creases rapidly.According to the partial discharge characteristic parameters of creepage discharge,the whole creepage discharge process is partitioned into four stages.Compared with unaged HTV silicone rubber,the aged HTV silicone rubber has less fluctuation in performance parameters and a clear trend.The study found that UV aging not only affects the physicochemical and hydrophobic properties of the HTV silicone rubber,but also accelerates the development of creepage discharge under AC voltage.

Efficiency of Portable Electronic Vulcanizer

This research was aimed at finding out the efficiency of the portable electronic vulcanizer. The old vulcanizing equipment was upgraded to save time, investment, manpower and to eliminate the problem of gas emission in vulcanization. The study also determined the accurate temperature setting and duration of vulcanizing process using electronic vulcanizer which eliminated the problem of gas emission produced by the conventional (gas fired) vulcanizer of about 2.772 kg of carbon dioxide for 1 liter of diesel fuel and/or 2.331 kg of carbon dioxide for 1 liter of petrol into the atmosphere. In constructing this vulcanizer, a letter G body configuration made of GI pipe with 31.5 cm long lag bolt with some electronic parts were installed, like the analog temperature gauge, digital timer, relay, LED, buzzer, switch, and heating element. Specifically, the product is divided into three components: base or body, control panel board and the heating unit. The effectiveness level of the equipment was tested utilizing five different temperatures at a constant and variable time. For Class A gum, the best temperature which bonded the gum exactly to the rubber tire was 60℃ in 1 minute while Class B gum was bonded at 60℃ in 2 minutes. The rate of energy consumed by the electronic vulcanizer for Class A gum was Php 0.0757 with an efficiency of 85.22% and for Class B gum was Php 0.15 with an efficiency of 85.22% and for conventional vulcanizer for Class A gum was Php 1.08 with an efficiency of 43.38% and for Class B gum was Php 1.52, with an efficiency of 78.08%. The study revealed that more tires could be vulcanized in a short period of time, therefore providing greater income over time. It is also environment-friendly since it does not emit carbon dioxide as compared to the conventional vulcanizing.

STUDY ON THE MISCIBILITY OF DYNAMICALLY VULCANIZED EPDM/PP BLEND BY POSITRON ANNIHILATION SPECTROSCOPY

Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume hole properties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncrystalline region of PP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent of EPDM was <50%. This was also demonstrated by DMTA and mechanical properties of the blends with various compositions.

Unveiling inverse vulcanized polymers as metal-free,visible-light-driven photocatalysts for cross-coupling reactions

Inverse vulcanized polymers(IVPs) that generated from elemental sulfur and smaller amounts of alkenes have found broad promising applications such as cathode materials for Li-S batteries, dynamic and repairable materials, optics applications, and metal sorption. However, their exploration in organic synthesis is still unprecedented. Here we first report the application of inverse vulcanized polymers in catalysis for organic transformations. A biomass-derived inverse vulcanized polymer(IVP-EAE) is found to be capable of catalyzing cross-coupling reactions in a transition-metal-free fashion under visible light.This method allows the direct C–H functionalization of pyrroles and N-arylacrylamides with(hetero)aryl halides, respectively, leading to the formation of two sets of structurally important scaffolds including pyrrole-containing biaryls and 3,3-disubstituted oxindoles with high selectivity. We anticipate this study will not only unveil the new potential of IVPs, but also offer a distinct type of catalysts for organic transformations.

Improving the Thermal Conductivity and Mechanical Properties of Twocomponent Room Temperature Vulcanized Silicone Rubber by Filling with Hydrophobically Modified SiO_2-Graphene Nanohybrids

The SiO_2 nanoparticles were coated on the surface of graphene oxide(GO) by sol-gel method to get the SiO_2-G compound.The SiO_2-G was restored and oleophylically modified to prepare hydrophobic modified SiO_2-G(HM-SiO_2-G) which was subsequently added to silicone rubber matrix to prepare two-component room temperature vulcanized(RTV-2) thermal conductive silicone rubber. The morphology, chemical structure and dispersity of the modified graphene were characterized with SEM, FTIR, Raman, and XPS methods.In addition, the heat-resistance behavior, mechanical properties, thermal conductivity, and electrical conductivity of the RTV-2 silicone rubber were also studied systematically. The results showed that the SiO_2 nanoparticles were coated on graphene oxide successfully, and HM-SiO_2-G was uniformly dispersed in RTV-2 silicone rubber. The addition of HM-SiO_2-G could effectively improve the thermal stability, mechanical properties and thermal conductivity of RTV-2 silicone rubber and had no great influence on the electrical insulation performance.

三维激光扫描和Vulcan软件在矿井下生产中的联合应用

应用Geoslam三维激光扫描技术,对玲珑金矿东风分矿井下残采、残出生产区域进行了大范围的多次扫描,并结合Vulcan三维软件对扫描数据进行处理、分析,详细客观的反映生产现状,将存窿矿石的体积、矿量、品位、合计金属量直观展现。为黄金生产从源头提供了准确的数据资料,达到对残采残出、充填治理、高品位矿柱回收等黄金生产工作的精益指导。

Waste Recovery and Sustainable Development. A Case Study of Material Development from Used Tires in Africa

This paper outlines a mechanical transformation process for rubber recycling, demonstrating the development of a new material from used tires. With the crumbs obtained using a crusher-compactor, a novel material for the manufacture of O-rings has been developed, with properties close to those found on the market. The process includes an experimental methodology of a sulfur vulcanization system choice and the quantification of ingredients, as well as the experimental determination of cure parameters. Mechanical tests on the samples completed the work by providing the mechanical characteristics of both unaged and aged (thermo-oxidative ageing) novel material. This process has a high potential for sustainable development and industrialization, making it a valuable contribution to the recycling of rubber in African developing countries.

阿舍勒铜锌矿床三维模型的研究

本文是在研究阿舍勒铜锌矿矿区地质及矿床地质的基础上,对该矿区的三维地质模型进行研究。主要探讨了该矿区的地质模型在计算机上实现三维可视化的可能,根据该区的地质工程资料,探索性的利用目前世界上较优秀的VULCAN软件系统建立矿区的钻孔三维模型,在此基础上根据矿体的空间赋存状态建立矿体的三维立体模型,进而建立矿区的三维地质模型,并进行矿体储量的估算,这将对深部地质的认识和矿山开采有重要意义。

VULCAN系统在我国露天矿中应用前景

VULCAN软件系统是由澳大利亚 MAPTEK公司开发成功的。该系统功能强大、内容丰富 ,主要用于地表及地下三维数据的处理 ,包括地质工程、环境工程、地理地形、测量工程、采矿工程、水库工程、地震分析等方面的数据处理及工程设计。VUL CAN有 PC版、工作站版等版本 ,操作使用方便、适应性强、性能优越 ,适合在我国露天矿推广应用 ,与我国自行开发的有关软件配合使用可达到优势互补、相互借鉴、促进提高软件开发水平的效果。

新疆阿舍勒铜锌矿床三维矿体模拟及资源评估

在 VUL CAN的软件环境下对新疆阿舍勒矿体进行三维计算机模拟和可视化研究 ,建立阿舍勒铜锌矿的三维矿体模型和地质模型 ,以便更直观的研究和分析矿体的形态变化规律 ;同时在把矿体细分为小的长方体块的基础上 。

A comparative study of the self-propelled jumping capabilities of coalesced droplets on RTV surfaces and superhydrophobic surfaces

Understanding the mechanism of coalescence-induced self-propelled jumping behavior provides distinct insights in designing and optimizing functional coatings with self-cleaning and anti-icing properties.However,to date self-propelled jumping phenomenon has only been observed and studied on superhydrophobic surfaces,other than those hydrophobic surfaces with weaker but fairish water-repellency,for instance,vulcanized silicon rubber(RTV) coatings.In this work,from the perspective of thermodynamic-based energy balance aspect,the reason that self-propelled jumping phenomenon does not happen on RTV coatings is studied.The apparent contact angles of droplets on RTV coatings can be less than the theoretical critical values therefore cannot promise energy surplus for the coalesced droplets onside.Besides,on RTV and superhydrophobic surfaces,the droplet-size dependent variation characteristics of the energy leftover from the coalescence process are opposite.For the droplets coalescing on RTV coatings,the magnitudes of energy dissipations are more sensitive to the increase in droplet size,compared to that of released surface energy.While for superhydrophobic coatings,the energy generated during the coalescence process can be more sensitive than the dissipations to the change in droplet size.

Surface Structure of Aged Composite Insulator Studied by Slow Positron Beam

Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin sample is smooth, while the outdoor aged samples are all rough. According to the S(E) curves obtained by slow positron beam, in a depth of more than 1 μm, the S parameter of the sample aged at low-potential side keeps the same value with the virgin one;while the S values of the highpotential side aged sample remain rather low in a depth of about 5 μm. Thermo gravimetric analysis(TGA) results show that the sample in high potential side contains more inorganic constituents than that of other samples. The results are attributed to the strong electric field induced corona aging at high potential side of the composite insulator.

表面改性炭材料在微生物燃料电池中的应用(英)

研究了在空气阴极微生物燃料电池中修饰方法如硝酸处理和硝酸-氨水酸碱等对XC-72R作为阴极氧还原催化剂催化活性的影响,并且使用傅里叶变换红外光谱(FTIR)、Boehm滴定法和X射线光电子能谱(谱(XPS)等手段对催化剂进行了表征.FTIR测试证明硝酸处理可引入含氧基团氨水处理可引入含氮基团.另外,还测试了含有不同表面官能团的XC-72R对氧还原的活性,并将其作为阴极催化剂用在MFC中,测试了电池性能.实验表明,经酸碱修饰的XC-72R作为空气阴极MFC的催化剂具有很好的应用前景.

澳大利亚Vulcan次盆Puffin油田油气源与成藏

Puffin油田目前油气来源不明,主力烃源岩展布及主要生、排烃期不确定都制约了下一步勘探的进行。利用烃源岩二维生烃模拟以及生物标志物指纹对比等方法,揭示了下Vulcan组海相泥页岩是本区最为重要的一套烃源岩,白垩纪—中新世为主要生、排烃期;而本区的Plover组烃源岩普遍演化程度较高,在晚侏罗世已达到高成熟,生烃潜力差,对于成藏的贡献较为有限,属于次要烃源岩。成藏事件图反映出Puffin垒带上的圈闭主要形成于侏罗纪—白垩纪,中新世以前由于侏罗系以上地层断裂不发育,下Vulcan组主力烃源岩生成的原油主要在地堑中的侏罗系圈闭中聚集成藏。中新世末,区域性的构造挤压运动形成众多垂向断裂并且使早期形成的断裂体系活化,使得早期成藏的油气垂向调整到浅层的白垩系聚集成藏。因此,目前Puffin油田发现的白垩系油藏主要为次生油藏,为早期侏罗系油藏调整改造到浅部垒带上形成。

VULCAN软件系统及其在元宝山露天矿的应用

软件系统功能强大,内容丰富,主要用于地表及地下三维数据的处理,形成三维立体模VULCAN型,包括地质工程、环境工程、地理地形、测量工程、采矿工程、水库工程、地震分析等方面的数据处理及工程设计。应用该软件成功地建立了元宝山露天煤矿的矿床地质模型,进行地质储量管理,形成彩场测量验收现状图,并编制各种开采生产计划。

Study the Effect of Recycled Tire Rubber on the Mechanical and Rheological Properties of TPV (HDPE/Recycled Tire Rubber)

Thermoplastic elastomeric blends prepared from blending of (10%, 20%, 30%, 40% and 50 wt%) high density polyethylene(HDPE) and (10%, 20%, 30%, 40% and 50 wt%) ground rubber tire (TPV-R). The blends prepared contain (HDPE)/polybutadiene (TPV-V). The two blends were successfully prepared through a dynamic vulcanization process, involving dicumyl peroxide (3%) as vulcanizing agent. The data of the mechanical (tensile strength at yield, %elongation and young modulus) and rheological properties (shear stress, shear rate, viscosity, flow behavior index and activation energy of melt flow) of the TPV-V and TPV-R showed that there was comparable results between the two blends.

基于Vulcan软件的山东莱州留村金矿区三维建模及资源量估值

留村金矿位于山东莱州市城区西南12 km的留村断裂带上,是发育于古老变质岩中的小型石英脉型金矿。为深入研究该矿区地层、构造与矿体在地下的延伸分布情况,加快后续数字化矿山建设,山东黄金集团应用Vulcan矿业软件对矿区开展三维地质建模。在收集相关地质实物资料的基础上,通过建立地质数据库、数据转换、地质解译等系列功能操作建立了矿区地表、岩体、构造及矿体模型,并对其进行任意剖割划分,实现了矿区地层岩性、地质构造、矿体的三维可视化,促进了本区矿体赋存规律的研究以及三维空间的成矿预测。同时利用软件强大的数据处理功能对资源量进行估值,本次估值的金资源量为1984.18 kg,与原详查报告中提交的金资源量2009.34 kg误差仅为1.25%。经估值后的每个矿块段都被赋予了精确的资源量数据,为后续矿山采矿设计与排产计划提供了准确的数据支撑,助力实现数字化、智能化矿山建设。

Study on Kinetics of Natural Rubber Vulcanization by S/La(DiPDP)_3

Kinetics of natural rubber （NR） vulcanization by lanthanum O, O＇-diisopropyldithiophosphate [ La（DiPDP）3 ] was studied. La（DiPDP）3 had remarkable accelerating effect on the vulcanization of NR. The rate constant k6 of the reaction that turned polysulphidic cross-links into the modified main chain was higher than that of desulfuration reaction of polysulfidic cross-links （k3 ）. The activation energies （Ea2, Ea3, and Ea6） of the formation, desulfuration, and decomposition of polysulfidic cross-links were 87.57,102.34, and 95.01 kJ · mol^-1, respectively. Activation energy （Eas） of the reaction that turned the cross-link precursors into the modified main chain was 82.67 kJ · mol^-1. It could be concluded that the proportion of polysulphidic cross-links was higher than mono- and di- sulphidic cross-links during induction and curing periods, mono- and di- sulphidic cross-links increased as curing temperature rose. In the temperature range of 140 - 160 ℃, the amounts of polysulphidic cross-links were similar. However, over 160℃, mono- and di- sulphidic cross-links increased rapidly. Moreover, cross-link density of the vulcanizates was determined from the equilibrium-swelling data. A chemical probe detected the concentration of polysulphidic cross-links of vulcanizates. The change trend of the results predicated from equation corresponded to that of the experimental results.

Radiation Vulcanization of Magnetorheological Elastomers Based on Silicone Rubber

The fabrication of magnetorheological （MR） elastomers was studied by two vulcanization methods, including heat vulcanization （HV） and radiation vulcanization （RV）, were employed to fabricate MRE samples. The dynamical mechanical properties were characterized by using a dynamic mechanic analyzer. In particular, both the MR effect and its durability were investigated. The experimental results showed that RV samples have large magnetoinduced modulus, large zero-field modulus, and good durability property of MR effect. To explain these results, cubic deformation and plasticizer migration were analyzed. Large magneto-induced modulus of RV sample results from cubic deformation during vulcanization process. And the plasticizer migration results in better durability of MR effect.