Chloroprene rubber blends

Thermogravimetry of the following rubber blends has been studied in detail by Lockmuller and co-workers [46] from the point of view of controlling decomposition mechanisms and minimisation of variance chloroprene rubber blends, butadiene-acrylonitrile rubbers, and rubber adhesives. These workers carried out a factor analysis in the TGA of rubber blends and butadiene-acrylonitrile copolymers using singular value decomposition and variance minimisation. 

NR is primarily utilized in the tyre industry because of its ideal properties. However, it has poor stability due to the existence of many double or unsaturated bonds. To improve the ambient stability of NR, synthetic rubber was chosen for blending. Zhang and coworkers blended and vulcanized NR and chloroprene rubber at a weight ratio of 75/25 by using a two-roll mill. The NR/ chloroprene rubber blends had improved mechanical properties in terms of their elongation strength and Shore A hardness. Moreover, the vulcanized chloroprene rubber blends had excellent oil resistance, thermal stability, selfextinguishing ability and ozone resistance. 

Park et al. [20] reported on the synthesis of poly-(chloroprene-co-isobutyl methacrylate) and its compati-bilizing effect in immiscible polychloroprene-poly(iso-butyl methacrylate) blends. A copolymer of chloroprene rubber (CR) and isobutyl methacrylate (iBMA) poly[CP-Co-(BMA)] and a graft copolymer of iBMA and poly-chloroprene [poly(CR-g-iBMA)] were prepared for comparison. Blends of CR and PiBMA are prepared by the solution casting technique using THF as the solvent. The morphology and glass-transition temperature behavior indicated that the blend is an immiscible one. It was found that both the copolymers can improve the miscibility, but the efficiency is higher in poly(CR-Co-iBMA) than in poly(CR-g-iBMA),... 

FIGURE 11.13 Lap shear versus % chloroprene rubber (CR) for CR-IR blends laminated between two steel substrates. (From Kardan, M., Rubber Chem. Technol., 74, 614, 2001.)... 

Blending Effect of EPDM with Chloroprene Rubbers, Technical Report, Mitsui Petrochemical Industries Ltd., Tokyo, Japan, 1969. 

Pentachlorthiofenol Renacit 7 RPA 6 USAF B-51. Peptizer for natural rubber, polyisoprene, styrene/butadiene rubber, polybutadiene, NBR, bu l, chloroprene and blends absorbed on clay, used as a peptizing agent facilitating open rnill and internal mixer mastication in rubber industry, Mildly toxic by ingestion severe eye irritant. Akrochem Chem. Co. Bayer AG Polysar. 

Construction Materials. Superabsorbent polsrmers are used to control liquid water in a variety of construction-related products. Joint-sealing composites are made by blending superabsorbents into chloroprene rubber (54) or into poly(ethylene-co-vinyl acetate) (55). These composites are used like mortar in the concrete block walls of the structure. Gaps left during construction are subsequently filled as the superabsorbent swells in any water, and subsequent leaks are prevented. A water-blocking construction backfill has also been developed from cement, water absorbing polymer, and an asphalt emulsion (56). 

The natural rubber does not generally exhibit all the desired properties for use in the rubber industry. Thus, it is possible to obtain better mechanical and physical properties at a lower cost by blending natural rubber with synthetic rubbers. Normally, natural rubber is deteriorated by ozone and thermal attacks due to its highly unsaturated backbone, and it also shows low oil and chemical resistances due to its non-polarity. However, these properties can be achieved by blending it with low unsaturated ethylene propylene diene monomer rubber, styrene butadiene rubber, carboxylate styrene butadiene rubber, nitrile butadiene rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, and acrylonitrile butadiene rubber. 

The blending of natural rubber with thermoplastics, and other rubbers have been reported in the literature. Thus, blends of NR with (i) ultra-low density polyethylene, (ii) styrene-butadiene rubber (SBR), (iii) epoxidized natural rubber, (iv) acrylonitrile butadiene rubber," (v) chloroprene rubber" and (vi) dichlorocarbene modified styrene-butadiene rubber (DCSBR)" have been prepared, characterized and reported in the literature. 

The most studied systems have been polypyrrole/ PVC blends [372-5]. The electrochemical polymerization of pyrrole on a platinum electrode covered with a film of PVC produces a dark-brown, ductile and flexible composite polymer film with an electrical conductivity comparable to polypyrrole (5-50 S cm ), and mechanical properties very similar to PVC. Bargon et al. [373] have observed that the mechanical properties of these PPy/PVC blends can be further improved by the addition of poly(chloroprene) rubber as a plasticizer. 

Macaione et al [235] have used TG for the characterisation of SBR, BR and NR in mono-, di-, or triblend rubber systems and carbon-filled rubber composites and determined the percentage of highly volatile organics, elastomer(s), carbon-black, and inorganic residue for each sample. Lochmiiller et al [194] applied factor analytical methods to evaluate TG results of a series of rubber blends and mixtures composed of chloroprene rubber, NBR, and common rubber additives. TG and measurements of toluene extractable matter of cured siloxane rubbers thermally aged in inert gas atmosphere at 80° C showed a build-up of low-MW fragments in the rubber network with age [244]. 

Thermal degradation and volatilization of chloroprene rubbers and blends thereof have been studied using thermogravimetric analysis. ... 

SBR Chloroprene Rubber Dichlorocarbene modified SBR (DCSBR) DCSBR addition to SBR/chloroprene blends showed enhanced mechanical properties in unfilled and carhon hlack filled hlends 134... 

Fuh and Wang [31] conducted studies involving Py-GC-MS for the analysis of nitrile rubber/chloroprene rubber materials. The peak ratio of l-chloro-4-(l-chloroethenyl) cyclohexane and benzonitrile was used for quantitative measurement of chloroprene/ nitrile rubber composition in vulcanised samples. Good linearity and recovery were achieved. A series of vulcanised chloroprene-nitrile rubber blended rubber materials was analysed using this method. Reasonable agreement between the estimated and the actual chloroprene composition of these commercial rubber materials was obtained. 

Solid-state 13C NMR has been used to identify elastomers in binary blends of chloroprene (CR) and NR, CR and CSM, NR and CSM, and SBR and acrylonitrile-butadiene rubber (NBR). The type of NBR can be determined by identifying the sequences of acrylonitrile and butadiene. The tertiary blend of NR/SBR/BR was also studied [49]. High-temperature 13C solid-state NMR identified ethylene-propylene diene terpolymer (EPDM) and fluoro and nitrile rubbers [50]. 

Figure 9.1. Phase-contrast micrographs of blends of chloroprene (CR), nitrile rubber (NBR), ethylene-propylene terpolymer (EPDM), and chlorobutyl rubber with styrene-butadiene rubber (SBR). The SBR phase appears white for the blends with CR and NBR, and dark for the blends with EPDM and chlorobutyl rubber. At low concentrations, the admixed rubber is the dispersed phase at higher concentrations, a phase inversion occurs and the admixed rubber becomes the matrix. (Callan et al, 1971.)...

In a recent paper, Agullo andBorros [13] have reported on an easy and rapid way of using TGA to determine qualitatively and quantitatively the type of polymer or polymer blend used in rubber compounds. The technique was applied successfully to a range of commonly used, commercially important polymers, including NR, EPDM, chlorosulphonated polyethylene and chloroprene. It was found that TGA alone could not differentiate between NBR and SBR, with another technique capable of detecting either styrene or acrylonitrile (pyrolysis GC-MS) being required to complement the data. 

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