动态硫化PVC/SBR共混体系的研究

采用动态硫化法制备了ＰＶＣ／ＳＢＲ共混物，考察了橡塑比、硫化体系、相容剂及ＰＶＣ交联对共混物性能的影响。结果表明，当ＰＶＣ／ＳＢＲ并用比为７５／２５，相容剂ＮＢＲ／氯化聚乙烯并用比为２．５／２．５，采用半有效或半有效加２份交联剂ＤＣＰ的硫化体系时，共混物综合性能较好。在ＰＶＣ中加入０．４份促进剂ＮＡ－２２可明显改善共混物的压缩永久变形。     

Improvement of the homogeneity of SBR/NBR blends using polyglycidylmethacrylate‐g‐butadiene rubber

Polyglycidylmethacrylate grafted butadiene rubber (PGMA‐g‐BR) was synthesized by a graft solution copolymerization technique. The PGMA content was determined through titration against HBr. The PGMA‐g‐BR was blended with styrene butadiene rubber/butadiene acrylonitrile rubber (SBR/NBR) blends with different blend ratios. The SBR/NBR (50/50) blend was selected to examine the compatibility of such blends. Compatibility was examined using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and viscosity measurements. The scanning electron micrographs illustrate the change of morphology of the SBR/NBR rubber blend as a result of the incorporation of PGMA‐g‐BR onto that blend. The T_gs of SBR and NBR in the blend get closer upon incorporation of PGMA‐g‐BR 10 phr, which indicates improvement in blend homogeneity. The intrinsic viscosity (η) versus blend ratio graph shows a straight‐line relationship, indicating some degree of compatibility. Thermal stability of the compatibilized and uncompatibilized rubber blend vulcanizates was investigated by determination of the physicomechanical properties before and after accelerated thermal aging. Of all the vulcanizates with different blend ratios under investigation, the SBR/NBR (25/75) compatibilized blend possessed the best thermal stability. However, the SBR/NBR (75/25) compatibilized blend possessed the best swelling performance in brake fluid. The effect of various combinations of inorganic fillers on the physicomechanical properties of that blend, before and after accelerated thermal aging, was studied in the presence and absence of PGMA‐g‐BR. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1559–1567, 2006     

HPVC/SBR共混体系相容性的研究

采用动态硫化方法制备高聚合度聚氯乙烯（ＨＰＶＣ）／ＳＢＲ共混型热塑性弹性体,考察了单一组分相容剂「相容剂分别为ＮＢＲ２７０、ＮＢＲ Ｐ６５、ＣＰＥ和氢化苯乙烯－丁二烯、苯乙烯嵌段共聚物（ＳＥＢＳ）」、复合相容剂（ＳＥＢＳ／ＮＢＲ和ＣＰＥ／ＮＢＲ）及交联程度对ＨＰＶＣ／ＳＢＲ共混体系相容性的影响。结果表明,使用复合相容剂可明显改善ＨＰＶＣ／ＳＢＲ共混物的性能;动态硫化在改善共混物力学性能方面起主要作     

Homogeneous Styrene Butadiene/Acrylonitrile Butadiene Rubber Blends

The graft copolymerization of acrylonitrile (AN) onto butadiene rubber (BR) was carried out in toluene at 80°C, using dibenzoyl-peroxide (BPO) as initiator. The synthesized poly acrylonitrile-grafted-butadiene rubber (AN-g-BR) was characterized by N% elemental analysis and Fourier-transform infrared (FT-IR) spectroscopy. Styrene butadiene rubber/acrylonitrile butadiene rubber (SBR/NBR) blends were prepared with different blend ratios in presence and absence of AN-g-BR, where the homogeneity of such blends were examined with intrinsic viscosity (η) measurements, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The scanning electron micrographs illustrate disappearance of the macro-scale phase separation of SBR/NBR rubber blend as a result of the incorporation of AN-g-BR into that blend. Viscosity measurements confirm homogeneity of that blend. Differential Scanning Calorimetry traces exhibit shifts in glass transition temperatures (T _g's) of SBR and NBR in their blend, indicating some degree of homogeneity. Physico-mechanical properties of the rubber blend vulcanizates with different blend ratios, in presence and absence of AN-g-BR, were investigated before and after accelerated thermal aging. The SBR/NBR (25/75) homogeneous blend possessed the best physico-mechanical properties after thermal aging, together with the best swelling behavior in motor oil. The physico-mechanical properties of SBR/NBR (25/75) filled blend with different types of inorganic fillers during thermal aging were studied.     

Transition of phase continuity induced by crosslinking and interfacial reaction during reactive processing of compatibilized PVC/SBR blends

Blends of 50 wt% of poly(vinyl chloride) (PVC) and 40 wt% of styrene butadiene rubber (SBR) with 10 wt% of acrylonitrile butadiene rubber (NBR) as the compatibilizer were prepared in a Haake mixer. An inversion of phase continuity was observed when the sulfur concentration was changed from 0.0 to 2.0 parts per hundred parts of resins (phr) in the blends containing an NBR with an acrylonitrile content of 29.5 wt% (NBR-29). The SBR phase, which is continuous in the unvulcanized blend, changes progressively into the dispersed phase as sulfur concentration increases. This is explained by the viscosity increase of the rubber caused by crosslinking. There is no phase inversion as a result of increasing sulfur concentration when the compatibilizer NBR-29 was replaced by an NBR with an acrylonitrile content of 40 wt% (NBR-40). The SBR phase is discrete in the unvulcanized blend with NBR-40 as the compatibilizer.

A change in phase continuity occurs during processing of the vulcanized PVC/NBR-29/SBR (50/10/40) blends. A torque peak in the torque curve during processing is correlated to the transition of the PVC phase continuity. There is a gradual increase in the torque curve after the torque peak. The rubber particle size decreases as a result of such a post-peak increase in the torque. The torque peak and the post-peak increase in the torque are absent in the case of the binary blends (PVC/NBR and PVC/SBR). The post-peak increase in the torque is attributed to the interfacial reaction between SBR and NBR that resides in the PVC phase.

A novel method developed recently was applied to study the interface development during processing. An interface with a higher rubber concentration develops during processing of the compatibilized blends.     

Study of the Effect of Natural Rubber-graft-maleic Anhydride (NR-g-MA) on the Compatibility of NR-NBR Blends Using the Ultrasonic Technique

The grafted copolymer of natural rubber (NR) and maleic anhydride (MA) was synthesized in a solution state by using ultraviolet radiation. The NR-g-MA was characterized using infrared (IR) technique. The prepared NR-g-MA was added to a 50/50 blend of NR and acrylonitrile-butadiene copolymer (NBR) as a compatibilizer. The effect of compatibilizer (NR-g-MA) concentrations in the range of 2, 4, 5, 6, 8, and 10 wt.% on the ultrasonic velocity, attenuation coefficient, and ultrasonic viscosity was studied in order to study the compatibility of the 50NR-50NBR blend. Ultrasound pulse echo method was used to measure both the ultrasound velocities and attenuation coefficient at a frequency of 2 MHz. Testing for elastic constant, Poisson's ratio, cross-link density, and microhardness was carried out in different percentages of the blend components to study the degree of the compatibility of the blend. The structure of the blend system was established by differential scanning calorimetry. The addition of NR-g-MA to the blend showed improvement of compatibility in certain concentration ranges and deterioration of compatibility in other ranges.     

The effect of glycidyl methacrylate and styrene comonomers on compatibility,physical-mechanical properties,and swelling behavior of SBR/NBR blends

The effect of functionalized styrene-butadiene rubber (SBR) with glycidyl methacrylate (GMA) monomers, in the presence of styrene comonomers (SBR-g-GMA-co-St) as a compatibilizer on physical-mechanical, morphological, and swelling behavior of SBR/nitrile butadiene rubber (NBR) blends were studied. It was proved that the compatibilizer made through dicumyl peroxide-induced reaction which possessed 1.5 phr GMA in addition to 1.5 phr styrene comonomers showed higher efficiency of grafting. Possible in situ reactions between SBR-g-GMA-co-St and NBR component also were evaluated with an attenuated total reflectance mode of Fourier-transform infrared spectroscopy. SBR/NBR blend containing compatibilizer with a middle value of grafting demonstrated the most reactions between components. Dynamic mechanical thermal analysis results illustrated that the presence of SBR-g-GMA-co-St caused a significant improvement in compatibility of two components. This was verified with the scanning electron microscope pictures in which a smoother surface of the sample was clear. The enhancement in microstructure led to an increase in tensile strength, elongation at break, and storage modulus. Moreover, the increase in the intermolecular cross-links and made interactions considerably affected blends' swelling behavior in both hydrocarbon solvents (carbon tetrachloride and chloroform).     

Mechanical and sorption properties of poly(ethylene-co-vinyl acetate)(EVA) compatibilized acrylonitrile butadiene rubber/natural rubber blend systems

Poly (ethylene-co-vinyl acetate) (EVA) has been used as a compatibilizer for heterogeneous natural rubber/acrylonitrile butadiene rubber (NR/NBR) blends. NR/NBR (50/50) blends were compatibilized with varying amounts, from 0 to 10 parts per hundred rubber (phr), of EVA. The compatibility of the blend components in presence of EVA has been evaluated in terms of mechanical and sorption characteristics. The mechanical properties were found to be improved by the addition of EVA upto 6 phr. The solvent resistance of the compatibilized samples has been observed to be higher compared to the uncompatibilized blends; attributed to the increased interfacial adhesion between the blend components. DSC studies showed a shift of glass transition temperatures of the blend components towards higher temperatures indicating increased rigidity of the matrix in presence of EVA.     

Mechanical properties of PVC/SBR blends compatibilized by acrylonitrile-butadiene rubber and covulcanization

The mechanical properties of poly(vinyl chloride) (PVC)/styrene-butadiene rubber (SBR) blends compatibilized by acrylonitrile-butadiene rubber (NBR) were studied. A sulfur curing system was employed to crosslink the rubber of the blends. In the case of the blends without any curing agents, an increase in NBR content did not improve the tensile strength and elongation-at-break. However, a significant improvement in the mechanical properties was observed when NBR was added as a compatibilizer and the blend was vulcanized. In the PVC/NBR/SBR (50/10/40) blends, the tensile strength and elongation-at-break increased with an increase in sulfur concentration. This improvement was attributed to covulcanization between NBR and SBR. The fracture toughness of PVC/NBR/SBR (50/10/40) blends was characterized by the critical strain energy release rate, G_c. In the case of the PVC/NBR-29/SBR (50/10/40) blends, an increase in sulfur concentration resulted in a dramatic increase in G_c. However, the G_c value of PVC/NBR-40/SBR (50/10/40) blends decreased with an increase in sulfur concentration owing to the brittle behavior of one of the blend components—the PVC/NBR-40 (50/10) phase.     

Development of novel elastomeric blends containing natural rubber and ultra-low-density polyethylene

This study sought to develop novel elastomeric compounds using natural rubber (NR) and ultra-low-density polyethylene (ULDPE). Blends were prepared by means of a two-roll mill for three ratios (70/30, 60/40, and 50/50 NR/ULDPE). Conventional vulcanization was performed in a compression mold. The physical and mechanical properties of the blend were determined according to ASTM standards. The results were compared with those obtained from NR blended with styrene-butadiene rubber (SBR). The morphological examinations with scanning electron microscopy indicated that ULDPE was compatible with NR; thus, the addition of a compatibilizer was not necessary. The cocontinuous phase was dominant in the NR/ULDPE blend containing 50 and 60 wt % NR. The tensile properties, tear resistance, and aging resistance of the NR/ULDPE blends were found to be superior to those of NR/SBR blends. On the other hand, the abrasion and flex cracking resistances of the NR/ULDPE blend were inferior to those exhibited by SBR blends but the Mooney viscosity and resilience of both blends fell in the same range. However, the addition of dicumyl peroxide appeared to have caused crosslinking of the ULDPE phase in the blend, which in turn increased the tensile properties and abrasion and aging resistance. The properties of the tertiary NR/SBR/ULDPE blend were investigated as well. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 650–660, 2001     

The Compatibilization of EPDM/SBR Blends by EPDM-Graft-Styrene Copolymer

Abstract

Ethylene propylene diene rubber (EPDM) and styrene butadiene rubber (SBR) blends were compatibilized by a graft copolymer EPDM-graft-styrene. This compatibilizer was prepared by gamma radiation induced grafting of EPDM with styrene monomer. The compatibilized blends were evaluated by scanning electron microscope and dielectric properties. The obtained results reveal that the addition of a small percentage of graft copolymer to EPDM/SBR blends improves the physico-mechanical properties of the blend vulcanizates, and this can be related to the enhancement of the blend compatibility.     

用合成相容剂制备NBR/PP动态硫化共混型热塑性弹性体的研究

用马来酸酐接枝聚丙烯（ＭＰ）／胺／端羧基液体工腈橡胶（ＣＴＢＮ）反应，生成ＰＰ－ＮＢＲ嵌段共聚物作为相容剂制备ＮＢＲ／ＰＰ动态硫化共混型热塑性弹性体效果很好，其中尤以ＭＰ／１．６－己二胺／ＣＴＢＮ效果最为理想。相容剂用量控制在６％左右。ＰＰ的熔融指数越小，共混体的性能越好。硫化体系采用酚酸树脂２４０２／氯化亚锡（８／０．５）、加入一定量的增塑剂邻苯二甲酸二辛酯和补强剂高耐磨炭黑，可获得性能较好的共混体。     

Effect of Addition of HDPE and LDPE on Rheological,Mechanical, Elastic and Compatibility Behavior of SBR/NBR Rubber Blend System

The influence of adding low density polyethylene (LDPE) and high density polyethylene (HDPE) to different ratios of styrene butadiene copolymer (SBR) and acrylonitrile butadiene copolymer (NBR) rubber blend has been studied. The experimental methods performed are based on measurements of rheological, mechanical, elastic properties, phase morphology, density, ultrasonic studies, thermal stability and differential scanning calorimetry (DSC). Results showed that rheological and mechanical properties of the blend are improved, especially at SBR/NBR blend (50/50), when incorporated with LDPE. Results indicated also a clear stability of the cure rate index (CRI) of the blend. Morphological structure analysis obtained from scanning electron microscope (SEM) showed a reduced domain size for blends containing LDPE. Ultrasonic and density investigations revealed the efficiency of adding LDPE in improving the compatibility behavior of this blend. Results also showed an improvement in elastic properties and thermal stability by adding LDPE. DSC scans of the blends filled with LDPE showed high shift in the glass transition temperature which can be attributed to the increased strength at the interface.     

Compatibilization of SBR/NBR blends using chemically modified styrene‐co‐butadiene rubber Part 2. Effect of compatibilizer loading

The present work focuses on the compatibization of styrene‐co‐butadiene rubber (SBR)/acrylonitrile‐co‐butadiene rubber (NBR) blends with dichlorocarbene modified styrene‐co‐butadiene rubber (DCSBR) as a function of concentration of compatibilizer and composition of the blend. FTIR studies, differential scanning calorimetry and dynamic mechanical analysis reveal molecular level miscibility in the blends in the presence of compatibilizer. The formation of interfacial bonding is assessed by analysis of swelling behaviour, cure characteristics, stress–strain data and mechanical properties. These studies show that the compatibilizing action of DCSBR becomes more prominent as the proportion of NBR in the blend increases. The resistance of the vulcanizate towards thermal and oil ageing improved with compatibilization. The change in technological properties is correlated with the crosslink density of the blends assessed from swelling and stress–strain data. © 2001 Society of Chemical Industry     

硅橡胶/EVM共混物性能的研究

考察了硅橡胶／橡胶型乙烯醋酸乙烯酯共聚物（ＥＶＭ）用量比、过氧化物品种及其用量、相容剂等因素对硅橡胶／ＥＶＭ共混物物理性能的影响。实验结果表明，硅橡胶／ＥＶＭ用量比大于１时，共混物强度性能主要受硅橡胶的影响；硫化剂选用ＤＣＰ较为合适；共混物的性能低于两种单一胶种性能的加和值，两胶种相容性较差；以乙烯基三乙氧基硅烷接枝ＥＶＭ作为相容剂，对该共混体系两相间的相容性有一定的改善。     

橡胶改性PP共混体系的研究

本文研究了SBR／PP共混比、硫化体系、不同橡胶以及增容剂对橡胶／PP共混物力学性能的影响。试验得出：橡塑比（SBR／PP）在30／70,采用半有效硫化体系（CZ／S）时,所制得共混物力学性能较好,共混体系PP／POE的综合性能比PP／EPDM、PP／SBR、PP／NBR共混体系要好,加入增容剂PP－g－MAH可以显著提高共混物的力学性能。     

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     

Compatibility studies on some polymer blend systems by electrical and mechanical techniques

Systematic electrical and mechanical studies were carried out on natural rubber (NR) blended with different types of synthetic rubber such as styrene‐butadiene rubber (SBR), polybutadiene rubber (BR), and ethylene‐propylene‐diene monomer (EPDM) as nonpolar rubbers and nitrile‐butadiene rubber (NBR) and chloroprene rubber (CR) as polar rubbers. The NR/SBR, NR/BR, NR/EPDM, NR/NBR, and NR/CR blends were prepared with different ratios (100/0, 75/25, 50/50, 25/75, and 0/100). The permittivity (ε′) and dielectric loss (ε″) of these blends were measured over a wide range of frequencies (100 Hz–100 kHz) and at room temperature (∼ 27°C). The compatibility results obtained from the dielectric measurements were comparable with those obtained from the calculation of the heat of mixing. These results were confirmed by scanning electron microscopy and showed that NR/SBR and NR/BR blends were compatible while NR/EPDM, NR/NBR, and NR/CR blends were incompatible. To overcome the problem of phase separation (incompatibility) between NR and EPDM, NBR, or CR, a third component such as SBR or poly(vinyl chloride) (PVC) was added as a compatibilizing agent to these blends. The experimental data of dielectric and mechanical measurements showed that the addition of either SBR or PVC could improve the compatibility of such blends to some extent. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 60–71, 2001