环保型增塑剂腰果壳油对丁腈橡胶性能的影响

研究了腰果壳油(CNSL)用量对丁腈橡胶胶料的硫化特性和硫化胶性能的影响,并与使用邻苯二甲酸二辛酯和环氧大豆油作为增塑剂进行了对比。结果表明,在0～30份(质量)用量内,加入CNSL后胶料的焦烧时间和正硫化时间有所缩短。与加入相同用量的邻苯二甲酸二辛酯和环氧大豆油的胶料及硫化胶相比,使用CNSL的胶料在硫化曲线上的最小转矩和最大转矩以及硫化胶的硬度、定伸应力和耐ASTM1#标准油体积增加率较小;硫化胶的拉伸强度、撕裂强度、扯断伸长率和耐ASTM3#标准油体积增加率较大;硫化胶的耐热空气老化性能较好。     

A comparative study of cardanol and aromatic oil as plasticizers for carbon‐black‐filled natural rubber

Cardanol is the main ingredient of cashew nut shell liquid, an agro‐byproduct. Its comparative merits vis‐a‐vis aromatic oil for plasticizing HAF‐black‐filled natural rubber (NR) is the subject of this article. Aromatic oil is the conventional plasticizer employed for such compounding requirements. The mechanical properties, ageing behavior, and torque time curves during cure of NR plasticized by both these materials are compared under identical conditions. It has been established that cardanol, when used as plasticizer, gives rise to similar tensile properties, shorter cure times, and superior ageing behavior compared to aromatic oil. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4835–4841, 2006     

The Effect of Dicumyl Peroxide Vulcanization on the Properties & Morphology of Polypropylene/Ethylene-Propylene Diene Terpolymer/Natural Rubber Blends

ABSTRACT

This article discusses some properties such as tensile properties, chemical and oil resistance, gel content, crystallinity, and morphology of polypropylene (PP)/ethylene-propylene diene terpolymer (EPDM)/natural rubber (NR) blends. Dicumyl peroxide (DCP) was applied as a crosslinking agent. In terms of tensile properties, peroxide vulcanized blend shows higher tensile strength and tensile modulus (stress at 100% elongation, M₁₀₀) as compared with the unvulcanized blend. The elongation at break of the peroxide vulcanized blend is higher for the blend with NR rich content compared with the EPDM rich content. The improvements in chemical and oil resistance as well as gel content of peroxide vulcanized blends have also proved the formation of crosslinks in the rubber phase. Scanning electron microscopy (SEM) micrographs from the surface extraction of the blends support that the crosslinks have occurred during dynamic vulcanization. Dynamical vulcanization with DCP has decreased the percent crystallinity of blends that can be attributed to the formation of crosslinks in the rubber.     

Plasticization effect of transgenic soybean oil. I. on ethylene propylene diene monomer (EPDM), as substitute for paraffin oil

Ethylene propylene diene monomer (EPDM) compounds were prepared with different amounts of transgenic soybean oil (TSO), a renewable and reactive plasticizer. For comparison, similar compounds were prepared with petroleum‐based paraffin oil (PO), one of the most common plasticizers for EPDM. The plasticization effects of TSO and of PO were studied by Mooney viscometry, capillary rheometry, differential scanning calorimetry (DSC), and rubber processing analysis (RPA). The results showed that TSO has better plasticization effect than PO on EPDM. In addition, the curing characteristics of the EPDM compounds were studied. TSO was found to react with the curing agent dicumyl peroxide (DCP) during the curing process. Excessive amounts of TSO led to low crosslinking density, which was improved by adjusting the added amount of DCP. The mechanical properties, extraction resistance, and thermal stability of the EPDM vulcanizates plasticized with different amounts of TSO and PO were compared to determine the optimum amount of TSO to replace PO. At the same amount and no more than 15 phr of plasticizer, the TSO‐plasticized EPDM vulcanizate has higher tensile and tear strength, elongation at break, extraction resistance, and thermal stability, but lower Shore A hardness than the PO‐plasticized EPDM vulcanizate. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4457–4463, 2013     

Kaolin modified with sodium salt of rubber seed oil as a reinforcing filler for blends of natural rubber,polybutadiene rubber and acrylonitrile–butadiene rubber

Blends of natural rubber (NR) and synthetic rubbers are widely used in the rubber industry to meet specific performance requirements. Further, the emerging field of organomodified clay/rubber nanocomposites could provide a host of novel materials having a unique combination of properties to meet various stringent service conditions. Previous studies have shown that at very low dosages, china clay (kaolin) modified with sodium salt of rubber seed oil (SRSO) improved the cure characteristics and physico‐mechanical properties of NR. Results of the present study show improved cure characteristics and physico‐mechanical properties for blends of NR with butadiene rubber and nitrile rubber containing 4 phr of SRSO‐modified kaolin as indicated by reduction in optimum cure time along with higher tensile strength, tensile modulus and elongation at break for their vulcanizates as compared to those containing unmodified kaolin. The SRSO‐modified kaolin/rubber nanocomposites showed improved flex resistance, reduced heat build‐up, tan delta and loss modulus and higher chemical crosslink density index, indicating a reinforcing effect of the SRSO‐modified kaolin, enabling the nanocomposites to have potential industrial applications. © 2015 Society of Chemical Industry     

PROPERTIES OF POLYPROPYLENE/NATURAL RUBBER/RECYCLE RUBBER POWDER BLENDS

Thermoplastic elastomers have been prepared by blending polypropylene (PP), natural rubber (NR), and recycle rubber powder (RRP). The blends were melt-mixed using a Brabender Plasticorder torque rheometer at 190°C and 50 rpm. A fixed 70:30 blend ratio (wt%) of PP and rubber was prepared. The effect of partial replacement of NR with RRP at a fixed rubber content (NR+RRP), 30 wt% on mechanical properties, swelling behavior, torque development, and morphological properties of PP/NR/RRP blends was studied. Results show that the tensile strength, Young's modulus, and swelling resistance increase with increasing RRP content in the PP/NR/RRP blends whereas the stabilization torque and elongation at break exhibit opposite trend.     

Properties of Polypropylene (PP)/Ethylene-Propylene Diene Terpolymer (EPDM)/Natural Rubber (NR) Vulcanized Blends: The Effect of N,N-m-Phenylenebismaleimide (HVA-2) Addition

This paper discusses process development, tensile properties, morphology, oil resistance, gel content, and thermal properties of polypropylene (PP)/ethylene-propylene diene terpolymer (EPDM)/natural rubber (NR) vulcanized blends with the addition of N,N-m-phenylenebismaleimide (HVA-2) as a compatibilizer. Blends were prepared in several blend ratios in a Haake Polydrive with temperature and rotor speed of 180°C and 50 rpm, respectively. Results indicated that the combination of dicumyl peroxide (Dicup) with HVA-2 shows high torque development and stabilization torque as compared to the blend with Dicup vulcanization alone. In terms of tensile properties, the combination of Dicup with HVA-2 shows higher tensile strength, tensile modulus (M₁₀₀), elongation at break, oil resistance, and gel content in all blend ratios compared to similar vulcanized blends with Dicup without HVA-2 addition. Scanning electron microscope (SEM) micrographs of the blends support that the cross-linking and compatibilization occur during the process of the vulcanized blend containing HVA-2. In the case of crystallinity of the blends, the addition of HVA-2 in Dicup vulcanized blend revealed a tendency for the percentage of crystallinity (Xc) to decrease. The addition of HVA-2 in Dicup vulcanization also produced blends with good thermal stability dealing with the so-called coagent bridge formation.     

A comparison of the properties of rice husk ash,silica, and calcium carbonate filled 75 : 25 NR/EPDM blends

The effects of incorporation of three different fillers, i.e., rice husk ash (RHA), silica, and calcium carbonate (CaCO₃), over a loading range of 0–60 phr on the curing characteristics, processability, mechanical properties, and morphology of 75 : 25 natural rubber (NR)/ethylene‐propylene‐diene monomer (EPDM) blends were studied using a conventional vulcanization system. Filler loading and type influence the processability of the blends in which RHA and CaCO₃ offer better processing advantage over silica. The best improvement in the tensile and tear strength and abrasion resistance of the 75 : 25 NR/EPDM blends with additional fillers was achieved when filled with silica. However, RHA and CaCO₃ were better in resilience property compared to that of silica. The RHA filled blends showed higher failure properties and abrasion resistance but lower ozone resistance than that containing CaCO₃. Scanning electron micrographs revealed that the morphology of the blend filled with silica is finer and more homogenous compared to the blend filled with RHA and CaCO₃. According to these observations, RHA can be used as a cheaper filler to replace CaCO₃ in rubber blends where improved mechanical properties are not so critical. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of trans-polyoctylene rubber (TOR) on the properties of NR/EPDM blends

trans-Polyoctylene rubber (TOR) was melt blended with an incompatible NR/EPDM (70/30) blend. Mixing torque and temperature were reduced as TOR was added to NR/EPDM blend. The curing characteristics of the blend were affected as TOR participated in vulcanization and became a part of network. A scanning electron micrograph demonstrated that addition of TOR improved the compatibility of the blend and thereby led to a finer phase morphology. The ozone resistance of the blends was determined in terms of a critical stress–strain parameter. The critical stored energy density for ozone cracking was significantly enhanced for the TOR containing rubber blend. It was believed that the improvement in ozone resistance arised from finely dispersed ozone-resistant EPDM particles in the blend. TOR caused an improvement in dynamic properties and an increase in tensile modulus, but a decrease in tensile stress and elongation at break of the rubber blend. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 749–756, 1999     

Influences of trans‐polyoctylene rubber on the physical properties and phase morphology of natural rubber/acrylonitrile–butadiene rubber blends

The influence of trans‐polyoctylene rubber (TOR) on the mechanical properties, glass‐transition behavior, and phase morphology of natural rubber (NR)/acrylonitrile–butadiene rubber (NBR) blends was investigated. With an increased TOR level, hardness, tensile modulus, and resilience increased, whereas tensile strength and elongation at break tremendously decreased. According to differential scanning calorimetry and dynamic mechanical analysis, there were two distinct glass‐transition temperatures for a 50/50 NR/NBR blend, indicating the strongly incompatible nature of the blend. When the TOR level was increased, the glass transition of NBR was strongly suppressed. NBR droplets of a few micrometers were uniformly dispersed in the continuous NR phases in the NR/NBR blends. When TOR was added to a 50/50 NR/NBR blend, TOR tended to be located in the NR phase and in some cases was positioned at the interfaces between the NBR and NR phases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 125–134, 2002     

Comparison Properties of Natural Rubber (SMR L)/Ethylene Vinyl Acetate (EVA) Copolymer Blends and Epoxidized Natural Rubber (ENR-50)/Ethylene Vinyl Acetate (EVA) Copolymer Blends

Mixing torque, morphology, tensile properties and swelling studies of natural rubber/ethylene vinyl acetate copolymer blends were studied. Two series of unvulcanized blends, natural rubber/ethylene vinyl acetate (SMRL/EVA) copolymer blend and epoxidized natural rubber (50% epoxidation)/ethylene vinyl acetate (ENR-50/EVA) copolymer blend were prepared. Blends were prepared using a laboratory internal mixer, Haake Rheomix polydrive with rotor speed of 50 rpm at 120°C. Results indicated that mixing torque value and stabilization torque value in ENR-50 blends are lower than SMRL blends. The process efficiency of ENR-50/EVA blends is better due to less viscous nature of the blend compared to SMRL/EVA blends as indicated in stabilization torque graph. Tensile properties like tensile strength, M100 (modulus at 100% elongation) and E _b (elongation at break) increase with increasing EVA fraction in the blend. At the similar blend composition, ENR-50 blend shows better tensile properties than SMRL blends. In oil resistance test, swelling percentage increased with immersion time and rubber composition. At a similar immersion time, ENR-50 blends exhibit better oil resistance compared to SMRL blends. Scanning electron microscopy (SEM) of tensile fractured surface indicated that EVA/ENR-50 blends need higher energy to cause catastrophic failure compared to EVA/SMRL blends. In etched cryogenically fractured surface, size and distribution of holes due to extraction of rubber phase by methyl ethyl ketone (MEK) were studied and holes became bigger as rubber composition increased due to coalescence of rubber particle.     

Mechanical properties,morphological structure,and thermal behavior of dynamically photocrosslinked PP/EPDM blends

A dynamically photocrosslinked polypropylene (PP)/ethylene–propylene–diene (EPDM) rubber thermoplastic elastomer was prepared by simultaneously exposing the elastomer to UV light while melt‐mixing in the presence of a photoinitiator as well as a crosslinking agent. The effects of dynamic photocrosslinking and blend composition on the mechanical properties, morphological structure, and thermal behavior of PP/EPDM blends were investigated. The results showed that after photocrosslinking, tensile strength, modulus of elasticity, and elongation at break were improved greatly. Moreover, the notched Izod impact strength was obviously enhanced compared with corresponding uncrosslinked blend. Scanning electron microscopy (SEM) morphological analysis showed that for uncrosslinked PP/EPDM blends, the cavitation of EPDM particles was the main toughening mechanism; whereas for dynamically photocrosslinked blends, shear yielding of matrix became the main energy absorption mechanism. The DSC curves showed that for each dynamically photocrosslinked PP/EPDM blend, there was a new smaller melting peak at about 152°C together with a main melting peak at about 166°C. Dynamic mechanical thermal analysis (DMTA) indicated that the compatibility between EPDM and PP was improved by dynamic photocrosslinking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3371–3380, 2004     

The effect of an epoxidized plasticizer on the thermo-oxidative ageing of poly(vinyl chloride)/epoxidized natural rubber thermoplastic elastomers

The effects of an epoxidized plasticizer on the mechanical properties and thermo-oxidative ageing behaviour of poly(vinyl chloride)/epoxidized natural rubber thermoplastic elastomers (TPEs) were investigated. Aged and unaged blends were characterized by FTIR, tensile properties, tear strength, hardness and dynamic mechanical analysis (DMA). The properties of the epoxidized soya oil (ESO) plasticized TPEs were compared with those of the di-2-ethylhexylphthalate (DOP) plasticized counterparts. The presence of epoxide groups in ESO has been shown to produce two conflicting effects. On the one hand, the presence of excessive epoxide groups has resulted in poor ageing behaviour. On the other hand, it has resulted in a good interaction and compatibility with PVC/ENR. It was found that the tensile strength of the ESO plasticized blends were comparable with the DOP plasticized ones, but the elongation at break (EB) of the ESO blends fell short of that of the DOP blends. Also the retention of both tensile properties for the ESO blends was poorer than for DOP blends. Hardening and embrittlement also occurred in the ESO blends. Despite these weaknesses, ESO could be an ideal plasticizer for the PVC/ENR system as indicated by plasticizer permanence and the greater efficiency of plasticization. © 1998 SCI.     

Improved mechanical properties of NR/EPDM blends by controlling the migration of curative and filler via reactive processing technique

Simple blending of natural rubber/ethylene–propylene–diene rubber (NR/EPDM) generally results in inferior mechanical properties because of curative migration and their differences for filler affinity. In this work, the 70/30 and 50/50 NR/EPDM blends prepared by reactive processing techniques were investigated and compared with the simple, nonreactive blends. The reactive blend compounds were prepared by preheating EPDM, containing all curatives to a predetermined time related to their scorch time prior to blending with NR. For the 70/30 gum blends, four types of accelerators were studied: 2,2‐mercaptobenzothiazole (MBT), 2,2‐dithiobis‐ (benzothiazole) (MBTS), N‐cyclohexyl‐2‐benzothiazolesulfenamide (CBS), and N‐tert‐butyl‐2‐benzothiazolesulfenamide (TBBS). When compared with the simple blends, the reactive blends cured with CBS and MBTS showed a clearly improved tensile strength whereas the increase of tensile strength in the blends cured with TBBS and MBT was marginal. However, a dramatic improvement of ultimate tensile properties in the reactive 50/50 NR/EPDM blends cured with TBBS was observed when compared with the simple blend. For the N‐550‐filled blends at the blend ratios of 70/30 and 50/50, the reactive‐filled blends prepared under the optimized preheating times demonstrated superior tensile strength and elongation at break over the simple blends. The improved crosslink and/or filler distribution between the two rubber phases in the reactive blends accounts for such improvement in their mechanical properties. This is shown in the scanning electron micrographs of the tensile fractured surfaces of the reactive blends, which indicate a more homogeneous blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of Phenol-CNSL Formaldehyde Copolymer on Thermal Ageing of Elastomers

Cashew nut shell liquid (CNSL) is a cheap agro-byproduct and renewable resource that consists mainly of substituted phenols. A CNSL-based resin was used in this study to modify the properties of the elastomers, chloroprene, CR and ethylene propylene rubber, EPDM. The resin was a copolymer obtained by condensing a mixture of phenol and CNSL with hexamethylenetetramine. The effect of the resin on the ageing properties of elastomers was studied by following changes in tensile strength, elongation at break, modulus, and tear strength. Comparison of the properties of the aged material containing resin with those of specimens not containing any modifiers shows improved ageing characteristics with respect to tensile strength, modulus, and tear strength.     

Radiation‐processed polychloroprene‐co‐ethylene–propene diene terpolymer blends: Evaluation of blend morphology,miscibility, and physical properties

The miscibility of polychloroprene rubber (CR) and ethylene–propylene–diene terpolymer rubber (EPDM) was studied over the entire composition range. Different blend compositions of CR and EPDM were prepared by initially mixing on a two‐roll mill and subsequently irradiating to different gamma radiation doses. The blends were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, density measurement, hardness measurement, and solvent permeability analysis. The compatibility of the blends was studied by measuring the glass transition temperature and heat capacity change of the blends. The immiscibility of blends was reflected by the presence of two glass transition temperatures; however, partial miscible domains were observed due to inter diffusion of phases. Permeation data fitted best with the Maxwell's model and indicated that in CR‐EPDM blends, EPDM exists as continuous phase with CR as dispersed phase for lower CR weight fractions and phase inversion occurred in 40–60% CR region. It was observed that CR improved oil resistance of EPDM; however, the effect was prominent for blends of >20% CR content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Natural rubber/ethylene propylene diene blends for high insulation iron crossarms

This research studied the composition and behavior of natural rubber (NR) and ethylene propylene diene monomer (EPDM) blends at various carbon black concentrations (0–30 phr) in terms of electrical resistivity, dielectric breakdown voltage testing, and physical properties. The blends having electrical properties suitable for application in high‐insulation iron crossarms were selected for investigation of compatibility and increased physical properties. The effect of the homogenizing agent concentration on improvement of compatibility of blends was studied by scanning electron microscopy, pulsed nuclear magnetic resonance spectroscopy, and rheology techniques. We also examined mechanical properties such as tensile strength, tear strength, elongation at break, and hardness. The NR/EPDM blends filled with a fixed concentration of silica were investigated for ozone resistance. A carbon black content as high as 10 phr is still suitable for the insulation coating material, which can withstand electrical voltage at 10 kVac. Addition of the homogenizing agent at 5 phr can improve the mechanical compatibility of blends, as evidenced by the positive deviation of shear viscosity of the rubber blend, that is, the calculated shear viscosity being higher than that of experimental data. Moreover, the pulsed NMR results indicated that the spin‐spin relaxation (T₂) of all three components of the rubber blend was compressed upon the addition of the homogenizing agent. The ratio of NR/EPDM in the blend to best resist the ozone gas is 80/20 with the addition of silica of 30 phr into the blend. Also, the NR/EPDM filled with silica had a decreased change in thermal and mechanical properties of blends after thermal aging. The synergistic effect of silica content and high NR content (80) in 20 phr EPDM could improve antioxidation by ozone in the absence of a normal antioxidant for natural rubber. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3401–3416, 2004     

NR/EPDM 的共硫化

利用环氧化天然橡胶(ENR)与天然橡胶(NR)和三元乙丙橡胶(EPDM)均有很好相容性的特点，采用硫化促进剂预混工艺对NR／EPDM并用胶实施共硫化。考察了其对NR／EPDM并用胶的硫化特性、硫化胶的物理机械性能和耐热空气老化性能的影响。结果表明：本工艺确实能改善NR／EPDM的共硫化性能，所得硫化胶物理性能较好且操作简单。     

Use of rice bran oil and epoxidized rice bran oil in carbon black–filled natural rubber–polychloroprene blends

In the present study we report the results obtained on the use of rice bran oil (RBO), a naturally occurring nontoxic oil, and its epoxidized variety (epoxidized RBO, or ERBO) in the compounding and vulcanization of different natural rubber–chloroprene rubber (NR–CR) blends. The processability, cure characteristics, and physical properties of the blends prepared with these oils were compared with those of control mixes prepared with aromatic oil. The optimum cure time and scorch time values of the different blends prepared with these oils were found to be lower than those of the respective control blends prepared with aromatic oil. Evaluation of physical properties of the different experimental blends showed that replacement of aromatic oil with these oils did not adversely affect their physical properties. Because RBO contains a good amount of free fatty acids it was tried as a coactivator in addition to its role as a processing aid. The level of these oils required for the blend preparation was optimized in a Brabender plasticorder. Physical properties such as tensile strength, elongation at break, tear strength, swelling index, and abrasion loss, for example, were evaluated for both experimental and control mixes. Comparison of cure characteristics and physical properties of the blends prepared with aromatic oil and with these oils showed that these oils could be used in place of aromatic oil in the above blends. It is also to be noted that aromatic oil is of petroleum origin and is reported to be carcinogenic. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4084–4092, 2003     

Mercapto‐modified copolymers in elastomer blends. IV. The compatibilization of natural rubber/EPDM blends

Ethylene—propylene—diene functionalized with mercapto groups (EPDMSH) was employed as compatibilizing agent for natural rubber (NR)/EPDM blends, resulting in a substantial increase of the ultimate tensile strength of these blends without affecting the elongation at break. There is also a decrease of the curing time with the addition of as low as 2.5 phr of EPDMSH, mainly in NR/EPDM (70:30 wt %) blend, indicating the accelerator effect of this functionalized copolymer. This copolymer also increased the crosslink degree and the gel content. From dynamic mechanical analysis (DMTA), it was demonstrated that EPDMSH improves the covulcanization process. The reactive compatibilization of EPDMSH was demonstrated by the presence of insoluble material in nonvulcanized/compatibilized blends and by its thermogravimetric (TGA) analysis. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2892–2900, 2002; DOI 10.1002/app.10283