导电SBS／SBR复合材料的研究

本文研究了碳黑填充充ＳＢＳ／ＳＢＲ复合材料的基本电性能，对复合材料电阻率随温度的变化特性进行了详细研究，讨论了碳黑种类，结构和性质，填充浓度以及ＳＢＳ含量对复合材料电阻率和电阻－温度特性的影响，实验结果指出，碳黑（Ｎ５５０）／ＳＢＳ／ＳＢＲ（ＳＢＳ：ＳＢＲ＝１：１ｗｔ）复合材料的电阻率随温度的变化呈一定温度的正温度系数（ＰＴＣ）效应。     

丁腈橡胶/导电粒子复合材料的正温度系数(PTC)特性

将导电粒子碳黑和铜粉分别与丁腈橡胶混合制备导电聚合物复合材料，其中碳黑（Ｎ５５０）／丁腈橡胶复合材料的电阻率随温度的变化呈现较强的正温度系数（ＰＴＣ）效应。讨论了掺入导电粒子浓度、结构和表面性质以及混炼硫化工艺等对该类材料的室温电阻率及ＰＴＣ效应的影响。     

纳米导电纤维与导电炭黑填充PVC复合材料的电性能研究

对纳米导电纤维(nano-F)及导电炭黑（HG－CB）填充PCV复合材料的电性能进行了研究,当nano-F和HG－CB的填充量分别为20,10份时,复合材料的电阻率急剧下降,其用量继续增加,材料电阻率变化不大。nano-F填充复合材料在20－120℃范围内电阻率基本不变,具有高的电阻稳定性,HG－CB填充复合材料在20－60℃范围内随温度升高阻率逐渐增大,之后随温度继续升高电阻率开始下降,nano-F填充复合材料的伏安特性在不同温度下为欧姆线性关系,而HGC－CB填充复合材料的伏安特性比较复杂。     

纳米导电纤维和导电炭黑并用填充硅橡胶复合材料的电性能

本文研究了纳米导电纤维（Nano-F）与导电炭黑（HG－CB）填充硅橡胶复合材料的电性能,Nano－F／HG—CB填充硅橡胶复合材料具有高的导电性;电阻率随温度增加在25～40℃之间呈负温度系数,而在40～120℃之间电阻率变化不大,具有较高的热稳定性;在不同温度下的伏-安特性呈欧姆线性关系．探讨了这种复合材料的导电机理．     

溶胶凝胶法制备的Mn系氧化物热敏薄膜的尺寸效应

本文阐述了用溶胶凝胶法制备ＣｏＭｎＣｕＯ等热敏薄膜的方法，研究了它们的电学性质。结果表明，薄膜的Ｒ－Ｔ特性基本符合Ｒ＝Ｒｏｅｘｐ（Ｂ／Ｔ）关系。在本文样品厚度的范围内，厚度对电阻率（ｐｔ）和材料常数（Ｂ）有较大的影响。利用扩展电阻仪分析了电阻率随深度的变化，用俄歇电子能谱分析了组分随深度的变化，在此基础上对尺寸效应作出了相应的解释。     

填充PPC/NBR共混弹性体研究(Ⅰ)加工条件和力学性能

本文研究了经碳黑填充、补强的聚丙撑碳酸酯（ＰＰＣ）／丁腈橡胶（ＮＢＲ）共混弹性体的加工条件和力学性能。发现加入ＰＰＣ能改善填充ＮＢＲ弹性体加工性，ＰＰＣ含量在１０％时填充弹性体力学强度存在最佳值。用马来酸酐改性能有效地提高填充共混弹性体耐油和热氧老化稳定性。     

PAN／Ni－P纤维和碳黑填充的HIPS复合材料的导电性

研究经化学镀镍的聚丙烯腈（ＰＡＮ）导电纤维（ＰＡＮ／Ｎｉ－Ｐ）填充的高抗冲聚苯乙烯（ＨＩＰＳ）复合材料的导电性与导电填料浓度的关系及加入有机钛酸酯偶联剂的影响、为了进一步提高复合材料的导电性，在ＰＡＮ／Ｎｉ－Ｐ纤维填充的复合材料中又加入不同量的碳黑，由于碳黑粒子的加入改善了纤维间的接触状态，更有利于导电网络的形成，从而大大提高了复合材料的导电能力。     

Nylon／SBR／NR复合材料的基本性能研究

研究了短纤维（Ｎｙｌｏｎ－６）补强弹性体（ＳＢＲ／ＮＲ）的基本物理机械性能，并对Ｎｙｌｏｎ／ＳＢＲ／ＮＲ复合体系在应力作用下的破坏结构进行了电子显微镜扫描。试验表明：短纤维形状系数，短纤维体积分数、弹性体基质与短纤维的粘合强度和短纤维在弹性体基质中的取向是影响Ｎｙｌｏｎ／ＳＢＲ／ＮＲ复合材料物理机械性能的主要因素。控制这４个变化因素，就能有效地设计其机械性能。     

电子束辐照对高密度聚乙烯/炭黑导电复合材料电阻率的影响

研究了电子束辐照固态和熔融态高密度聚乙烯／炭黑（ＨＤＰＥ／ＣＢ）导电复合材料的电性能随辐照温度和辐照剂量的变化。结果表明,对固态或熔融态辐照材料而言,其电阻率均随温度的升而而增大。等剂量下,固态辐照材料的ＰＴＣ强度比熔嘈态辐照的要高,两各状态经高剂量辐后其材料ＮＴＣ效应消失,,ＤＳＣ测试证明电阻率的２与基体的结晶行为以及交联链的形成密切相关。     

炭黑／聚丙烯／聚碳酸酯复合材料导电性能和PTC特性

以聚丙烯（PP）／聚碳酸酯（PC）共混物为基体,采用不同种类炭黑（CB）填充制备导电复合材料并对其导电性能和PTC特性进行研究。结果表明：在常温时,PP／PC共混基体中PP含量大于40wt％时,材料的电阻率急剧下降;共混比为50：50（wt％）复合材料的电阻率达到最小值。加热时,两者均未出现明显NTC现象,说明PP／PC的共混可以有效的消除NTC效应。但PTC强度仅为1个数量级,远低于PP／CB二元复合材料。CB是影响PTC效应的重要因素之一,达到逾渗值时随着体系CB含量减少PTC效应会增强;乙炔炭黑与炉法CB填充的CB／PP／PC复合材料相比较,前者的体积电阻率较低,而两者的逾渗阈值相近,均为6．6％;乙炔CB为填料的CB／PP／PC三元复合材料的阿C突变温度在140℃附近,以炉法CB为填料时,PTC效应突变点出现在150℃（PC的Tg）附近。DSC分析结果表明,复合材料中PP的结晶度随着CB含量增加呈上升趋势,CB含量为15％时,PP的结晶度为32．75％,对于整个PP／PC／CB体系而言结晶部分的含量较低,因此该体系的PTC效应强度较低。     

Microstructural studies of the interactions in SB rubber and mesoporous silica mixtures

Precipitated silicas have been utilized successfully as rubber reinforcing fillers instead of carbon black. The development of new mesoporous silicas with properties different than the precipitated silicas, specially their high BET surface areas and their organized pore structures with pore sizes between 1.5–10 nm, make them potential materials in rubber reinforcing. The knowledge of the interactions between rubber and its filler at a fundamental level is important to understand the physical and mechanical properties of a filled rubber system. This paper presents a comparative microstructural analysis of the interactions of the styrene butadiene rubber (SBR) with mesoporous silica and with Ultrasil VN3 silica, made on mixtures prepared in a rheometer at 150 °C and their toluene extracted residues. Solid state nuclear magnetic resonance, Fourier transform infrared (FTIR), thermogravimetry (TGA), scanning electron microscopy (SEM) and nitrogen adsorption isotherms, show a relation between the strength of the interaction and the particle size and pore structure characteristics of the mesoporous materials. Such a material prepared under certain specific conditions shows better interaction with the rubber than Ultrasil VN3 silica. Electronic Publication     

Reinforcement and antioxidation effects of antioxidant functionalized silica in styrene–butadiene rubber

In order to improve the dispersion of silica in rubber matrix and to avoid volatility and extractability of the antioxidants, antioxidant functionalized silica is synthesized through reaction of precipitated silica and antioxidant coupling agent which is synthesized by (3-glycidyloxypropyl)trimethoxysilane (A-187) and N-phenyl-1,4-phenylenediamine (PPDA). This antioxidant functionalized silica with different antioxidant content is then incorporated into styrene–butadiene rubber (SBR) to study their reinforcement and antioxidation effects. The tensile strength of these composites is much higher than that of neat silica/SBR, and increases with increasing antioxidant content. It is close to that of bis(triethoxysilylpropyl)tetrasulfane (TESPT) modified silica/SBR when the antioxidant content exceeds 3.9% (by weight to silica). Furthermore, SBR filled with antioxidant functionalized silica has greatly improved stability in thermal oxidative ageing and damp heat ageing.     

Styrene–butadiene latex modified calcium aluminate cement mortar

This paper investigates properties of calcium aluminate cement (CAC) mortar modified with the styrene–butadiene-rubber (SBR) latex. This material may be advantageously applied as a rapid repair mortar. Mortar specimens were prepared with constant water-to-cement mass ratio; polymer solid content of latex was varied from 0% to 9%, and Li₂CO₃ was investigated as an accelerator. Specimens were treated at different curing conditions: 1, 7 days and transformation of metastable hydration products at 70 °C. The heat of hydration evolution of mortar specimens was measured by means of a self adopted isoperibol calorimeter.The measurement results indicate that SBR latex improves workability of fresh state mortar and retards nucleation and growth of hydration products. Due to polymer coagulation process and co-matrix formation permeability, stiffness and compressive strength decrease while adhesion strength to old concrete substrate, and flexural strength increase with amount of added latex.     

The effects of electron beam irradiation on the thermal properties,fatigue life and natural weathering of styrene butadiene rubber/recycled acrylonitrile–butadiene rubber blends

The effects of electron beam (EB) irradiation on the thermal properties, fatigue life and natural weathering of styrene butadiene rubber/recycled acrylonitrile–butadiene rubber (SBR/NBRr) blends were investigated. The SBR/NBRr blends were prepared at 95/5, 85/15, 75/25, 65/35, or 50/50 blend ratios with and without the presence of a 3 part per hundred rubber (phr) of polyfunctional monomer, trimethylolpropane triacrylate (TMPTA). Results indicate that the crystallisation temperature (T_c) observed in polymeric blends is due to the alignment of polymer chains forming a semi-crystalline phase. Addition of TMPTA helps to align polymer chains through crosslinking. More crosslinking occurred between polymer blends with the help of TMPTA, upon irradiation. The improvement in fatigue life can also be associated with the stabilisation of SBR/NBRr blends upon irradiation and irradiation-induced crosslinking, which was accomplished with relatively low radiation-induced oxidative degradation in the presence of TMPTA. The tensile properties of both blends decreased over the periods of environmental exposure due to the effect of polymer degradation. After 6 months, the irradiated SBR/NBRr blends could not retain better retention [mainly with 25, 35 or 50 phr of recycled acrylonitrile–butadiene rubber (NBRr) particles] due to the samples becoming brittle over the long period of outdoor exposure.     

NBR/PFPA动态硫化热塑性弹性体的研制

为了获得耐热油、高强度的油封材料，我们采用机械共混方法制备了ＮＢＲ／ＰＦＰＡ－Ⅲ动态硫化热塑性弹性体，并研究了其返炼加工特性。结果表明，利用密炼机制备的热塑性弹性体具有优良的物理力学性能和成型加工性能。经初步应用，使用效果良好，具有广阔的应用前景。     

纳米石墨片-羧基丁腈橡胶复合材料结构形态与电性能

利用电子束辐照法制备纳米石墨片(GnPs)-羧基丁腈橡胶(XNBR)复合材料,研究辐射剂量对胶乳共混体系稳定性的影响,并对GnPs-XNBR复合材料的交联度、热稳定性、电性能及其形貌予以表征。结果表明:辐照后GnPs-XNBR复合材料的交联度、热稳定性和体积电阻率提高,而共混乳液的稳定性显著降低。辐照强化了乳胶粒子与石墨片之间的界面结合,形成胶乳粒子包覆石墨片的核-壳结构,进而提高石墨片在基体中分散均匀性,并使GnPs-XNBR复合材料的热稳定性和介电常数提高,导电性和介电损耗降低。     

Effect of grafting cellulose acetate and methylmethacrylate as compatibilizer onto NBR/SBR blends

Compatibilizer is used for improving of processability, interfacial interaction and mechanical properties of polymer blends. In this study acrylonitrile butadiene rubber (NBR) and styrene-butadiene rubber (SBR) blends were compatibilized by a graft copolymer of acrylonitrile butadiene rubber (NBR) grafted with cellulose acetate (CA) i.e. (NBR-g-CA) and acrylonitrile butadiene rubber (NBR) grafted with methylmethacrylate i.e. (NBR-g-MMA). Compatibilizers were prepared by gamma radiation induced grafting of NBR with cellulose acetate (CA) and methylmethacrylate (MMA) were added with different ratios to NBR/SBR (50/50) blend. The compatibilized blends were evaluated by rheometric characteristics, physico-mechanical properties, swelling behavior, scanning electron microscope (SEM) and thermal analysis. The results showed that, the blends with graft copolymer effect greatly on the rheological characteristics [optimum cure time (Tc₉₀), scorch time (Ts₂), and the cure rate index (CRI)]. The physico-mechanical properties of the investigated blends were enhanced by the incorporation of these graft copolymers, while the resistance to swelling in toluene became higher. SEM photographs confirm that, these compatibilizers improve the interfacial adhesion between NBR/SBR (50/50) blend which induce compatibilization in the immiscible blends. The efficiency of the compatibilizer was also evaluated by studying the thermogravimetric analysis.     

Additive Manufacturing of Porous Structures for Unmanned Aerial Vehicles Applications

Unmanned aerial vehicles (UAVs) have shown promising benefits in many applications. This has been enabled by the emergence of additive manufacturing (AM), which give the designers a large amount of geometrical freedom. In this paper, a novel design process of fused deposition modeling (FDM) combining both topology and infill optimization is introduced for AM of high performance porous structures. Tensile testing of FDM printed samples is first carried out to study the effect of the build orientation on the mechanical properties of acrylonitrile butadiene styrene (ABS) samples. It is found that samples built perpendicular to the load axis are the weakest with a tensile strength of 29 MPa and Young's modulus of 1960 MPa. The materials properties are fed to the finite elements analysis (FEA) for geometrical topology optimization, aiming to maximize stiffness and reduce weight of those parts. Afterwards, an infill optimization is carried out on the topology optimized parts using different mesostructures such as honeycomb, triangular, and rectangular to achieve high structural performance. The results showed that triangular pattern with 50% infill density had the lowest developed stresses, less mass, and strain energy when compared to other structures. Optimum UAVs parts of a quadcopter are successfully manufactured, assembled, and tested.

     

Performance analysis of a thick copper-electroplated FDM ABS plastic rapid tool EDM electrode

The importance of rapid tooling (RT) and additive manufacturing (AM) appears to be indispensable for boosting the process of manufacturing and expanding the horizon of production technology worldwide. This concept draws the attention of numerous scholars to arrive at a conclusive theory for the widespread utilization of RT. This study attempts to determine the viability and performance of an RT electrode in the field of electro discharge machining (EDM). The electrode prototype is made using an acrylonitrile butadiene styrene (ABS) plastic by fused deposition modeling (FDM), an AM technique, electroplated with copper of desired thickness, and used in die sinking EDM of D2 steel. The scanning electron microscope analysis of the electroplated samples confirms that it is possible to obtain the desired thickness of the metal by electroplating on any electrically conductive surface. In the present work, an experimental study is performed for examining the electroplated copper thickness of the plastic EDM electrode and its performances. It is found that the electroplated ABS plastic EDM RT electrode successfully performs the machining operation of D2 steel, and the results are comparable with a solid electrode. The study reveals that the RT electrode can be regarded as a viable tool for rough cutting or semi-finishing cut EDM functions. The experimental results are thoroughly discussed, examined, analyzed, and evaluated for the purpose of developing the appropriate form of the concept.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-018-0238-5