纳米氢氧化镁/橡胶复合材料的性能研究

以纳米氢氧化镁粉体为分散相研究对象,制备纳米氢氧化镁／NBR、纳米氢氧化镁／EPDM、纳米氢氧化镁／SBR和纳米氢氧化镁／硅橡胶4种复合材料,研究其物理性能和阻燃性能。结果表明,纳米氢氧化镁赋予复合材料良好“无卤”阻燃性能的同时,具有优异的补强效果;纳米氢氧化镁粉体分散度越高,与基体的界面作用越强,复合材料的物理性能越好;纳米氢氧化镁对：NBR补强效果最好,对硅橡胶的补强效果最差。对纳米氢氧化镁粉体进行表面处理,可提高其在EPDM中的分散度,增大其与橡胶间的界面作用力,从而显提高EPDM复合材料的物理性能。     

氢氧化铝对复合绝缘子用硅橡胶的性能影响研究

研究了氢氧化铝的粒径及填充量对复合绝缘子用热硫化硅橡胶的力学性能、电学性能、阻燃性、憎水性能的影响。实验结果表明：当氢氧化铝粒径为2.4μm时,硅橡胶的力学性能及阻燃性能达到最佳,憎水性及电学性能适中;氢氧化铝填充量为115～125份之间时,硅橡胶综合性能最佳,漏电起痕达到1A4.5,阻燃性能满足FV-0。     

HDPE/BN复合材料的热导率

研究了高密度聚乙烯(HDPE)／氮化硼(BN)复合材料中BN分散状态、含量及粒径对热导率的影响。用粉末混合法制得的复合材料中BN粒子围绕在HDPE粒子周围,形成特殊的网状导热通路,在(?)(BN)为30％时复合材料的热导率达1．20 W／(m·K),是纯HDPE的4倍。随BN粒径减小,复合材料的热导率升高,小粒子在基体中形成导热通路能力优于大粒子。HDPE／BN复合材料具有优良的电绝缘性能和机械性能。     

Electrical conductivity and mechanical properties of polyaniline/natural rubber composite fibers

Electrically conducting elastomer fibers based on natural rubber (NR) and up to 10% w/w polyaniline (PANI) in its emeraldine base (EB) form were fabricated by a wet spinning process. The resulting fibers at various PANI contents were doped by immersion in aqueous HCl solution, which converted the PANI to the electrically conductive emeraldine salt (ES) form. The morphology of the composite fibers was studied by scanning electron microscopy (SEM). PANI particles were inhomogeneously distributed in the NR matrix. The electrical conductivity of the fibers increased with the increasing PANI‐ES content and leveled off at a value of around 10^?3 S/cm at PANI‐ES concentration of 5% w/w. The fibers retained most of their elasticity upon doping, while the tenacity was somewhat reduced. Gratifyingly, the electrical conductivity of the new elastomer fibers was preserved upon elongational deformation, even if strains as large as 600% were applied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

甲基乙烯基硅橡胶和氧化铝的干燥温度对其复合材科导热性能的影响

以Al2O3粉体为导热填料、甲基乙烯基硅橡胶(MVQ)为基体制得MVQ/Al2O3导热复合材料.研究了MVQ和Al2O3的干燥温度对MVQ/Al2O3体系导热性能的影响,并考察了体系的填料网络结构.结果表明,MVQ的干燥温度越高.其小分子挥发分越低,复合材料的导热性能越好.Al2O3的干燥温度越高,其残余水分含量越低;...     

Development of correlation between potassium hydroxide number and conductivity of concentrated natural rubber latex

Increase in the ion concentration in the medium was found to increase conductivity and potassium hydroxide number (KOH No) in natural rubber latex (NRL). Addition of long chain fatty acids can increase the ion concentration in the medium and stability of NRL. A series of concentrated natural rubber latex samples from three different areas with different soils and climatic conditions were tested for the parameters such as KOH No and conductivity. They have been measured over a period of 62 days, upon addition of soap to natural rubber latex concentrate. The result showed that there was a strong positive linear correlation between conductivity and KOH No. The regression equation to express the relationship between the variables has also been found. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

硅橡胶/丁苯橡胶并用胶的制备及表征

针对硅橡胶具有较高的耐热性,但力学性能差;丁苯橡胶(SBR)力学性能较好,但粘性较差;提出了将硅橡胶与SBR共混,制成共混材料;采用偏光显微镜、傅里叶变换红外光谱、差示扫描量热仪以及力学性能、热老化性能测试手段,研究了甲基乙烯基硅橡胶(MVQ)/SBR共混体系的并用比(质量比)、硫化工艺参数以及顺丁橡胶(BR)的加入对力学性能、耐热老化性能和相容性的影响。结果表明:MVQ与SBR最佳配比为30/70,白炭黑为45份;最佳硫化工艺参数为170℃×10 MPa×30 min。MVQ/SBR并用胶的玻璃化温度为-20℃,MVQ和SBR具有较好的相容性。     

Reactive compatibilization of a nitrile rubber/phenolic resin blend: Effect on adhesive and composite properties

Resole phenolic resins containing various p-cresol (PC) to phenol (P) mol ratios were prepared and characterized. These phenolic resins were blended with nitrile rubber (NBR) and the measurements of adhesive joint strength, stress–strain properties, DSC, TGA, DMA, TEM, and SEM were performed using a 50 : 50 NBR/phenolic resin blend. It was observed that the adhesive joint strength and the mechanical properties of the blend enhanced significantly on incorporation of p-cresol into the phenolic resin, and the optimum p-cresol/phenol mol ratio was in the vicinity of 2 : 1. Observation of a more continuous phase and the increase in T_g of the rubber region in the blend indicated increased reactivity and compatibilization of NBR with phenolic resin as p-cresol was incorporated. The effect of silica filler on the properties of the nitrile rubber/phenolic resin blend was also studied without and with p-cresol modification and the results suggest that silica filler take not only the role of a reinforcing filler in the nitrile–phenolic–silica composite, but also a role as surface compatibilizer of the blend components. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1187–1201, 1998     

Electrical conductivity and electric modulus of stable Kevlar® fiber loaded HAF/NBR rubber composite

DC, AC conductivities and dielectric properties of high abrasion furnace carbon black (HAF)/acrylonitrile butadiene rubber (NBR) composite have been studied with varying the aramide Stable Kevlar^® fiber content, temperature, and frequency. Generally, the electrical conductivity was decreased with increasing Stable Kevlar^® fiber content, which was confirmed by the positron annihilation lifetime spectroscopy. Negative temperature coefficient of conductivity (NTCC) behavior between 353 and 413 K was detected, except for the composite containing 10 phr Kevlar which showed positive temperature coefficient of conductivity (PTCC) behavior above 383 K. These NTCC and PTCC behaviors were further manifested by differential scanning calorimetry (DSC). For the composite with 10 phr Kevlar, the interfacial polarization between the fibers and the polymeric composite can be ascribed to Maxwell‐Wagner‐Sillars mechanism. The (MWS) relaxation disappeared for higher fibers content. The analysis of the electric modulus in the frequency range from 1 kHz to 1 MHz shows that the interfacial relaxation obeys Cole–Davison distribution of relaxation times. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

镀银玻璃微珠/硅橡胶导电复合材料导电性能的影响因素

研究镀银玻璃微珠的用量、粒径、表面改性工艺以及导电硅橡胶硫化程度等对镀银玻璃微珠/硅橡胶复合材料导电性能的影响.结果表明,镀银玻璃微珠的粒径越大,复合材料的导电性能越好;湿法预处理和原位改性-分散工艺制得复合材料的导电性能和导电稳定性优于直接干混工艺;导电硅橡胶硫化程度的提高有利于提高材料的导电性能;Payne效应的大小与导电硅橡胶的体积电阻率有很强的相关性.     

Thermal conductivity of PVDF/PANI-nanofiber composite membrane aligned in an electric field

Poly(vinylidene fluoride)(PVDF) is a semi-crystalline thermoplastic polymer with excellent thermal stability,electrochemical stability and corrosion resistance, which has been widely studied and applied in industrial nonmetallic heat exchanger and piezoelectric-film sensor. In this study, polyaniline(PANI) nanofibers were synthesized using dodecylbenzene sulfonic acid as the surfactant. The obtained PANI nanofibers were blended in PVDF matrix to enhance thermal conductivity and tensile strength of composite materials. Electric field was applied for the orientation of membrane structure during membrane formation. Scanning electron microscope(SEM) images exhibited that the PANI nanofibers were well-dispersed in the composite membranes. The structure of composite membranes was more orderly after alignment. X-ray diffraction(XRD) and differential scanning calorimetry(DSC) indicated that the content of PANI nanofibers contributed to the transformation of PVDF from α-phase to β-phase. Both the tensile strength and thermal conductivity of composite membranes were significantly improved. This tendency was further enhanced by the application of electric field. The maximum tensile strength was obtained when the content of PANI nanofibers was 3 wt%, which was 46.44% higher than that of pure PVDF membrane. The maximum thermal conductivity of composite membranes after alignment was 84.5% greater than that of pure PVDF membrane when the content of PANI nanofibers was 50 wt%. The composite membrane is a promising new potential material in heat transfer field and the mechanism explored in this study would be informative for further development of similar thermal conductive polymeric materials.     

Control of morphology and properties in multicomponent polymers based on polystyrene/polyester block copolymers

Abstract

The morphology and properties of multicomponent polymers based on polystyrene/polyarylate block copolymers (PS–b–PAr) are investigated. The PS–b–PAr molecule was synthesised by a novel procedure using carboxy terminated polystyrene. The architectures of the PS–b–PAr copolymers were predicted by a kinetic simulation model. Based on the results of the simulation and analysis of morphology, both the optical and mechanical properties of the PS–b–PAr are explained. The domain size, which dominates the transparency, was found to be sensitive to the purity of the block copolymer, while the birefringence was determined not only by the PS/PAr ratio but also by the length of each segment. On the basis of the experimental analyses, conditions were designed for the synthesis of PS–b–PAr copolymers with high transparency and low birefringence. The mechanical properties of the PS–b–PAr were controlled by modification of the miscibility between the PS and PAr segments. Acrylonitrile was introduced into the PS chain as a miscibility modifier. The volume fraction of the interfacial layer increased with the increase in miscibility. In particular, around the acrylonitrile concentration at which the miscibility reaches a maximum, the flexural strength was dramatically improved, changing the fracture behaviour from brittle to ductile. Furthermore, the PS–b–PAr copolymer was used as a compatibiliser for several immiscible polymer blend systems, including high impact polystyrene–polycarbonate and polyamide 6–acrylonitrile/butadiene/styrene. In these applications the PAr unit was used not as a macromolecular anchor but as a reactive unit. The experimental results showed that PS–b–PAr could compatibilise these blend systems effectively via an in situ reaction between the PAr chain and either polycarbonate or polyamide 6 during the melt mixing process.     

Durability studies of aluminium/ aluminium joints bonded by chlorobutyl rubber-carboxylated nitrile rubber and epichlorohydrin rubber-carboxylated nitrile rubber blends

Two novel rubber blends based on chlorobutyl rubber ( )-carboxylate nitrile rubber ( ) and epichlorohydrin rubber (ECO)-carboxylated nitrile rubber ( ) can be used as adhesives for aluminium/aluminium bonding. Incorporation of silica filler in the blend and carbon black in the blend improves joint strength. The adhesives show remarkable water and salt water resistance. The adhesives based on show remarkable heat and water resistance. Heat stability of the adhesives based on is not satisfactory but can be improved by the application of silane primer on the aluminium surface. Silane primer also improves the paraffin oil resistance. The increase in joint strength resulting from the application of silane primer is due to the formation of Si-O-Al linkages at the aluminium/primer interface.     

Thermal conductivity of alumina inclusion/glass matrix composite materials: local and macroscopic scales

The thermal conductivity of a two-phase material, based on a glass matrix containing mm sized spherical alumina inclusions, has been studied as a function of the alumina phase volume fraction. The glass matrix and the alumina phase were chosen with almost identical coefficients of thermal expansion to ensure good thermal contact at the interface between the two phases. The thermal conductivity of the alumina phase was determined by local measurements on the inclusions using the mirage technique. For the glass phase and the two-phase samples, the thermal conductivity values were evaluated with the laser flash technique and compared to predictions by analytical models. The Maxwell–Eucken model gives a close agreement to these experimental values for alumina volume fractions up to 55%. In fact, we show that for large mm sized alumina inclusions, Hasselman's correction for the interface thermal resistance is not necessary.     

Preparation and characterization of polymethyltrifluoropropylsilicone modified acrylonitrile–butadiene rubber/fluorosilicon rubber blend

The blending of polymethyltrifluoropropylsilicone‐modified acrylonitrile–butadiene rubber (MNBR) and fluorosilicon rubber (FSR) at 70 : 30 ratio was investigated. The grafting of mercapto‐functionalized polymethyltrifluoropropylsilicone onto acrylonitrile‐butadiene rubber (NBR) by thiol‐ene reaction was carried out with 2,2′‐azobisisobutyronitrile as initiator in a Haake torque rheometer. The rheological properties of NBR grafting obtained at varying dosages of polymethyltrifluoropropylsilicone in a Haake torque rheometer were studied using torque curves. Grafting reaction was confirmed by ¹H nuclear magnetic resonance and energy‐dispersive X‐ray spectroscopy. Results of scanning electron microscopy and dynamic mechanical analysis showed better compatibility of MNBR/FSR blend than NBR/FSR reference blend. Meanwhile, the macro‐mechanical properties of the blend significantly improved. The tensile strength and tear strength of MNBR/FSR blend were improved to 14.34 MPa and 44.94 KN/m, respectively, which were 2.92 MPa and 13.03 KN/m higher than those of NBR/FSR reference blend. The low‐temperature brittleness of the blend was improved to ?57°C, an increase of ?6°C compared with that of NBR. These results indicated that MNBR/FSR blend at 70 : 30 ratio had improved compatibility because of the grafting chains that acted as interfacial agents. The low‐temperature resistance of the blend was also enhanced. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42328.     

Effect of mineral fillers on physico-mechanical properties and heat conductivity of carbon black-filled SBR/butadiene rubber composite

Iranian Polymer Journal - Heat conductivity, curing rate and fatigue crack growth properties of carbon black-filled styrene butadiene rubber (SBR)/butadiene rubber (BR) blend that is frequently...     

Co-compatibilising effect of carbon nanotubes and liquid isoprene rubber on carbon black filled natural rubber/polybutadiene rubber blend

Abstract

Bis-(triethoxysilylpropyl)-tetrasulfane functionalised carbon nanotubes (t-CNTs) were used as compatibiliser along with liquid isoprene rubber (LIR) in the natural rubber (NR)/polybutadiene rubber (BR) blend. Their reinforcing and compatibilising effects were evaluated by mechanical, fatigue crack growth resistance properties and blend homogeneity. Scanning electron microscope and transmission electron microscope showed enhanced interfacial adhesion between the binary rubber phases and improved dispersion of the minor phase in the rubber blend respectively with the co-existence of LIR and carbon nanotubes. The tensile strength of the carbon black (CB) filled NR/BR blend reached its optimum when 3 phr CB was replaced with an equal amount of t-CNTs in the presence of 7 phr LIR, while the fatigue crack growth resistance property achieved its maximum in the presence of 3 phr LIR. This interesting co-compatibilisation behaviour of t-CNTs and LIR suggests that t-CNTs have a better effect than CB with the assistance of LIR, which is an effective plasticiser in the NR/BR blend.     

Thermal aging kinetic and effects on mechanical behavior of fully recycled composite based on polypropylene/polyethylene blend

The effect of thermal oxidation of a fully recycled carbon fibers reinforced stabilized polypropylene/polyethylene blend on the mechanical properties has been studied at 120, 130 and 140 °C. In a first step, several analyses by FTIR and UV spectrometry and differential scanning calorimetry were performed in order to detect and monitor the evolution of the antioxidants and oxidation products in the materials. This approach aims to well understand and identify the aging mechanisms that will be modeled in a second step in a kinetic model capable of predicting the evolution of carbonyl build‐up while taking into account the presence of the different antioxidants. Modeling results showed a good correlation between the kinetic behavior and the obtained experimental data. Furthermore, the effect of thermal aging on the mechanical behaviors of the composite and the matrix were studied at the macroscopic scale at different strain rates. It has been shown that the thermal oxidation affects only the elongation at break. The numerical values of the oxidation products generated by the kinetic model allowed linking the evolution of the mechanical behavior under aging with the physicochemical state of the material. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46640.     

Effect of rubber ratio,carbon black level,and accelerator level on natural rubber/bromobutyl rubber blend properties

Statistical experimental design, that is, response surface methodology, was used to predict and explain the effects of rubber ratio, carbon black, and accelerator level on the cure characteristics and physical properties of natural rubber/bromobutyl rubber (NR/BIIR) blends. With these three independent variables, 20 designed compounds were mixed by a two‐roll mill and the scorch time, cure time, cure rate index, together with physical properties (hardness, tensile property, and compression set) were all determined by one operator. Multiple linear regression analysis was used to obtain response equations and thus contour plots, which illustrate the effects of the three independent variables on each property, as shown in detail by the diversity of interactions between independent factors and each property. It was found that the carbon black level is the most significant influential factor on scorch time, cure time, tensile properties, hardness, and compression set. The difference in reactivity toward sulfur vulcanization of NR and BIIR resulted in cure behavior and physical properties that are dominated by the NR content in the rubber ratio factor. Finally, the response equations were shown to be useful for making accurate predictions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3059–3068, 2003     

硅橡胶/EPDM泡沫合金材料的结构与性能

分别采用电镜和激光共聚焦显微镜研究了硅橡胶／EPDM泡沫合金的结构均匀性和泡孔结构,并进行强伸性能,压缩性能和阻尼减震性能的研究,结果表明,采用硅烷偶联剂后,硅橡胶／EPDM共混物的分散均匀性较好;泡沫合金的密度小于0．55Mg.m^-3,泡孔均匀,平均孔径小于80um,且泡沫合金的拉伸强度,压缩性能和阻尼减震性能优于硅橡胶泡沫。