Natural Rubber-Acrylate Blends

The History of Natural Rubber-Acrylate Blends and IPNs... 

Normally, the morphological properties of natural rubber-acrylate blends and IPNs are firstly investigated to identify their compatibilities. Several techniques. 

Standard-grade PSAs are usually made from styrene-butadiene rubber (SBR), natural rubber, or blends thereof in solution. In addition to rubbers, polyacrylates, polymethylacrylates, polyfvinyl ethers), polychloroprene, and polyisobutenes are often components of the system ([198], pp. 25-39). These are often modified with phenolic resins, or resins based on rosin esters, coumarones, or hydrocarbons. Phenolic resins improve temperature resistance, solvent resistance, and cohesive strength of PSA ([196], pp. 276-278). Antioxidants and tackifiers are also essential components. Sometimes the tackifier will be a lower molecular weight component of the high polymer system. The phenolic resins may be standard resoles, alkyl phenolics, or terpene-phenolic systems ([198], pp. 25-39 and 80-81). Pressure-sensitive dispersions are normally comprised of special acrylic ester copolymers with resin modifiers. The high polymer base used determines adhesive and cohesive properties of the PSA. 

Volume 1 of this book is comprised of 25 chapters, and discusses the different types of natural rubber based blends and IPNs. The first seven chapters discuss the general aspects of natural rubber blends like their miscibility, manufacturing methods, production and morphology development. The next ten chapters describe exclusively the properties of natural rubber blends with different polymers like thermoplastic, acrylic plastic, block or graft copolymers, etc. Chapter 18 deals entirely with clay reinforcement in natural rubber blends. Chapters 19 to 23 explain the major techniques used for characterizing various natural rubber based blends. The final two chapters give a brief explanation of life cycle analysis and the application of natural rubber based blends and IPNs. 

Furthermore, the C=C bonds in the natural rubber structure might induce poor thermal and oxidative resistance in the natural rubber blends. Thus, Thawornwisit and coworkersproposed the preparation of hydrogenated natural rubber, which is one of the chemical modifications available to improve the oxidation and thermal resistance of diene-based natural rubber before blending with poly(methyl methacrylate-co-styrene). The poly(methyl methacrylate-co-styrene) was resistant to the outdoor environment and had excellent optical properties with a high refractive index, but it was extremely brittle and had low impact strength. Hydrogenated natural rubber could, however, be used as an impact modifier, as well as to improve its thermal and oxidative resistance for these acrylic plastics. 

Acrylate polymers are often used in many applications that require good optical properties. However, they are unsuitable for use in the automotive industry because of their brittle characteristics. Thus, when natural rubber is blended with poly(methyl methacrylate), there is a big improvement in the elasticity of the brittle acrylate polymers. It is of interest that thermoplastic natural rubbers are relatively new products in the rubber industry and are fastgrowing items in the polymer market. The acrylate polymers blended with natural rubber can improve various properties of both the natural rubber and the acrylate polymers such as elasticity, adhesion, processability properties, and transparency. These materials are known for their excellent processability, characteristic of acrylate polymers, and their elasticity property provided by natural rubber, thus they exhibit the typical properties of elastomeric materials and can be processed with thermoplastic processing equipment used to prepare acrylate polymers. Many of their interesting properties have been widely developed for several industrial applications such as in the automotive industry, household appliances, medical devices, electrical cables, and headphone cables. ... 

Ellul [27] subjected EPDM/polypropylene and natural rubber/polypropylene blends to various halogenation treatments, namely fluorine/carbon dioxide, sodium hypochlorite/ acetic acid and bromine water. With the natural rubber blend, there was a substantial uptake of fluorine, chlorine and bromine in the surface regions as indicated by energy dispersive X-ray analysis and with all three pre-treatments the adhesion to an acrylic tape was greatly enhanced. In contrast, with the EPDM blend, fluorine was the only reagent which reacted with the rubbers and only this treatment resulted in a significant increase in adhesion to the acrylic tape. The above results can be explained in terms of the different concentrations of carbon-carbon double bonds in the two blends. Substantial incorporation of chlorine and bromine could occur with the natural rubber-polypropylene blend but not with the EPDM blend. However, fluorine gas will react readily with saturated hydrocarbons [28,29] and therefore the incorporation of fluorine into the EPDM blend is not surprising. 

Several flexible polymers, such as natural rubber (NR) synthetic rubber (SR) polyalkyl acrylates copolymers of acrylonitrile, butadiene, and styrene, (ABS) and polyvinyl alkyl ethers, have been used to improve the impact resistance of PS and PVC. PS and copolymers of ethylene and propylene have been used to increase the ductility of polyphenylene oxide (PPO) and nylon 66, respectively. The mechanical properties of several other engineering plastics have been improved by blending them with thermoplastics. 

As a result of its saturated polymer backbone, EPDM is more resistant to oxygen, ozone, UV and heat than the low-cost commodity polydiene rubbers, such as natural rubber (NR), polybutadiene rubber (BR) and styrene-butadiene rubber (SBR). Therefore, the main use of EPD(M) is in outdoor applications, such as automotive sealing systems, window seals and roof sheeting, and in under-the-hood applications, such as coolant hoses. The main drawback of EPDM is its poor resistance to swelling in apolar fluids such as oil, making it inferior to high-performance elastomers, such as fluoro, acrylate and silicone elastomers in that respect. Over the last decade thermoplastic vulcanisates, produced via dynamic vulcanisation of blends of polypropylene (PP) and EPDM, have been commercialised, combining thermoplastic processability with rubber elasticity [8, 9]. 

Silaprene . [Uniroyal] Industrial adhesives and sealants based on chloro-prene, PVC acrylic, nitrile, natural rubber, SBR, PC, ABS, urediane, or epoxy or blends. 

Fig. 14 UV-curing of various blends of EPI with HDDA (20 wt %). Photoinitiator [TAS] = 3 wt % ENR epoxidized natural rubber ECR epoxidizedcyclized rubber. Epoxy conversion acrylate conversion...

Highly recommended for these polymers PVC, PV c, PS, PMMA, PP, PF, PA, PE, acrylics, nitrocellulose, cellulosic resins, EP, EC, NBR, SBR, natural rubber, PU, phenolic resins, CA, NC, ABS/ PC, PPO blends (wifli HIPS and other polymers). ... 

This technique has found the following applications in addition to those discussed in Sections 10.1 (resin cure studies on phenol urethane compositions) [65], 12.2 (photopolymer studies [66-68]), and 13.3 (phase transitions in PE) [66], Chapter 15 (viscoelastic and rheological properties), and Section 16.4 (heat deflection temperatures) epoxy resin-amine system [67], cured acrylate-terminated unsaturated copolymers [68], PE and PP foam [69], ethylene-propylene-diene terpolymers [70], natural rubbers [71, 72], polyester-based clear coat resins [73], polyvinyl esters and unsaturated polyester resins [74], polyimide-clay nanocomposites [75], polyether sulfone-styrene-acrylonitrile, PS-polymethyl methacrylate (PMMA) blends and PS-polytetrafluoroethylene PMMA copolymers [76], cyanate ester resin-carbon fibre composites [77], polycyanate epoxy resins [78], and styrenic copolymers [79]. 

Blends and IPNs of Natural Rubber with Acrylic Plastics... 

Natural rubber blends have not been substantially limited to only reactive blends, such as those produced by grafting, epoxidation and halogenation studies. IPNs are one choice for modification of the natural rubber to increase the compatibility between natural rubber and acrylate polymers. Full IPNs of natural rubber and acrylate polymers are defined as a polymer blend having a crosslinked polymerization of each polymer type in their networks. Semi-IPNs, in contrast, are those in which only one type of polymeric component, mostly acrylate polymer, is crosslinked. The polymerization of IPNs would be a potential method for the modification of natural rubber. ... 

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