Chlorosulfonated polyethylene rubber properties

As a consequence, before 1953, the only possible blends were those of LDPE with other polymers than PO or with elastomers (e.g., chlorosulfonated polyethylene rubber, CSR chlorinated butyl mbber, CBR ethylene/propylene/diene copolymers, EPR, EPDM thermoplastic olefinic elastomer TPE, TPO). However, in addition to the original autoclave polymerization, already in 1938, a tubular reactor was introduced and its product had different properties than that from the autoclave. Also varying the reaction condition affected the degree of short- and long-chain branching in LDPE thus, blending different LDPEs offered a way for optimizing the resin to specific applications. 

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 sulfonation of polyethylene membranes was examined under various experimental conditions and the results showed that sulfonation greatly enhanced the water permeability of the resultant membranes. A lower concentration of chlorosulfonic acid at low temperature was preferable, so that only the surface and inner walls of the polymer were sulfonated and the mechanical properties of the membrane were not damaged. The electromicroscopy of polythene is facilitated by staining the polymer by immersing pieces of the polymer in chlorosulfonic acid at 60 °C for several hours. Chlorosulfonated polyethylene rubbers are useful for specific purposes, e.g. as ozone-resistant hoses. ... 

The chemical name for Hypalon is chlorosulfonated polyethylene and it has excellent resistance to heat, ozone and oxidising chemicals and has good abrasion resistance. It can be compounded for outstanding resistance to oxidising chemicals, such as sodium hypochlorite solutions in sulfuric acid saturated with chlorine and concentrated phosphoric acid. It is one of the few synthetic rubbers that can be mixed in any colour without loss in mechanical properties. 

Protective crack-resistant coatings, based on chlorosulfonated polyethylene (CSPE), are widely known due to their unique crack- and corrosion-resistant properties as compared to other rubbers. These coatings also have high ozone, weather, and wear resistance, as well as excellent mechanical and dielectric characteristics. 

Chlorosulfonated polyethylene s)mthetic rubber (CSM) is manufactured by DuPont under the trade name H) alon. In many respects it is similar to neoprene, but it does possess some advantages over neoprene in certain types of service. It has better heat and ozone resistance, better electrical properties, better color stability, and better chemical resistance. 

Donskoi and co-workers [54] showed that each of the components of a chlorosulfonated polyethylene (CSPE) mix has its own influence on the fireproofing properties and chemical processes that occur. In this case, the thermal properties of the vulcanisates of CSPE were studied, and also the heat flows from the flame on the surface of the specimen. It was established that the thermooxidative breakdown of CSPE and vulcanisates based on it during heating under dynamic conditions, is a multi-stage process. The results of tests involving various fillers and plasticisers made it possible to create rubber-like, high-impact resistant materials. 

Chlorosulfonated polyethylene is a saturated chlorohydrocarbon rubber produced from CI2, SO2, and a number of polyethylenes, and contains about 20 to 40% chlorine and 1 to 2% sulftir as sulfonyl chloride. Sulfonyl chloride groups are the curing or cross-linking sites.2 CSM properties are largely based on initial polyethylene (PE) and percent chlorine. A free-radical-based PE with 28% chlorine and 1.24% S has a dynamic shear modulus range from 1000 to 300,000 Ib/in (7 MPa to 2.1 GPa). StiflEhess differs for free-radical-based PE and linear PE, with chlorine content at about 30%, CI2 free-radical-based PE stiffness decreases to minimum value, and at about 35%, CI2 content linear PE stiffness decreases to minimum value. When the CI2 content is increased more than 30 and 35%, respectively, the stiffness (modulus) increases.23... 

Ethylene acrylic mbber is manufactured by M/s Dupont USA under the trade name of Vamac, and is about half ethylene and half methylacrylate. A small amount of cure site monomer in the molecule provides the ability to cross-link chemically. This rubber is the combination of two major chemicals which give its unique balance of properties. For instance, the backbone structure of the polymer molecule is saturated, and so it is inherently resistant to ozone attack. The acrylic segment provides oil resistance, and the ethylene segment yields low temperature performance. The added feature of this mbber is that there is no halogen present to become corroded. There is slightly more tendency to swell than a homopolymer, such as polyacrylate or acrylonitrile mbber, but it is approximately equal to silicone, chloroprene and Hypolan (chlorosulfonated polyethylene) mbbers. 

EPDM successfully competes with other rubbers (butyl, chloroprene, and chlorosulfonated polyethylene) and other materials (PVC, bitumen compounds, and composites), offering quite satisfactory ageing/weathering characteristics associated with good/excellent mechanical properties at a rather low cost. Table 29 illustrates such an application. 

Although the base resin is usually polyethylene, other base resins, ie, polypropylene (6), ethylene propylene copolymers (7), and polymers containing additional functionality (ie, vinyl acetate, acrylic or methacrylic acid, and maleic anhydride graft) have been chlorinated and chlorosulfonated commercially. This family of polymers is widely used in rubber and adhesive industries because of the valuable properties that can be achieved when properly compoimded and vulcanized. 

---