Chlorinated polyethylene, chemical resistance

Polypropylene has a chemical resistance about the same as that of polyethylene, but it can be used at 120°C (250°F). Polycarbonate is a relatively high-temperature plastic. It can be used up to 150°C (300°F). Resistance to mineral acids is good. Strong alkalies slowly decompose it, but mild alkalies do not. It is partially soluble in aromatic solvents and soluble in chlorinated hydrocarbons. Polyphenylene oxide has good resistance to ahphatic solvents, acids, and bases but poor resistance to esters, ketones, and aromatic or chlorinated solvents. 

Chlorinated polyethylene CPEs provide a very wide range of properties from soft/ elastomeric to hard. They have inherent oxygen and ozone resistance, have improved resistance (compared to PEs) to chemical extraction, resist plasticizers, volatility, and weathering. Products do not fog at high temperatures as do PVCs and can be made flame retardant. 

Chemical resistance is generally good up to 60°C but polyethylenes are attacked by oxidizing acids, chlorinated solvents, certain oxidants, aromatic hydrocarbons. 

The chemical resistance is generally inferior to that of comparable polyethylenes and decreases when VA rises. EVAs are attacked by concentrated strong acids, halogens, oxidizing acids, chlorinated solvents, certain oxidants, aliphatic and aromatic hydrocarbons, alcohols, ketones, esters, and some others. 

The moderate random chlorination of polyethylene suppresses crystallinity and yields chlorinated polyethylene elastomer (CPE), a rubber-like material that can be crosslinked with organic peroxides. The chlorine (Cl) content is in the range of 36 to 42%, compared to 56.8% for PVC. Such elastomer has good heat and oil resistance. It is also used as a plasticizer for PVC. They provide a very wide range of properties from soft/elastomeric too hard. They have inherent oxygen and ozone resistance, resist plasticizers, volatility, weathering, and compared to PEs have improved resistance to chemical extraction. Products do not fog at high temperatures as do PVCs and can be made flame retardant. 

Lead stabilisers have been used in a variety of PVC as well as other polymers for many years. In some halogenated polymers, such as chlorinated PE (CPE), chlorosulphonated polyethylene (CSM), polychloroprene (CR) and epichlorohydrin (ECO), dibasic lead phthalate and dibasic lead phosphite are used to scavenge HC1 arising from crosslinking as well as from degradation. In some of these cases, the metal may participate in crosslink formation. With lead-based stabilisers, the result is typically a product with greater water and chemical resistance than if a light metal, with more soluble halide salts, were used instead. In other cases, lead stabilisers may be used solely for function in metal oxide... 

Chlorinated polyethylene resistance tables are available from the Dow Chemical Company (Plaquemines, LA). 

Specifically, PVC blends with polyethylene, polypropylene, or polystyrene could offer significant potential. PVC offers rigidity combined with flammability resistance. In essence, PVC offers the promise to be the lowest cost method to flame retard these polymers. The processing temperatures for the polyolefins and polystyrene are within the critical range for PVC. In fact, addition of the polyolefins to PVC should enhance its ability to be extruded and injected molded. PVC has been utilized in blends with functional styrenics (ABS and styrene-maleic anhydride co-and terpolymers) as well as PMMA offering the key advantage of improved flame resistance. Reactive extrusion concepts applied to PVC blends with polyolefins and polystyrene appear to be a facile method for compatibilization should the proper chemical modifications be found. He et al. [1997] noted the use of solid-state chlorinated polyethylene as a compatibilizer for PVC/LLDPE blends with a significant improvement in mechanical properties. A recent treatise [Datta and Lohse,... 

Chlorinated Polyethylene and Polypropylene. Totally chlorinated polyethylene and polypropylene have a chlorine content of 64 68%. Their properties largely correspond to those of chlorinated rubber (see Section 2.3). Chlorinated polypropylenes can be used for chemical-resistant and weather-resistant coatings. These binders are important in adhesion priming coats and heat-sealing lacquers for polypropylene foils. 

The arrangement of elements in the molecule, the symmetry of the structure, and the polymer chains degree of branching are as important as the specific elements contained in the molecule. Polymers containing the carbon-hydrogen bonds such as pol5 ropylene and polyethylene, and the carbon-chlorine bonds such as PVC and ethylene chlorotrifluoroethylene are different in the important property of chemical resistance from a fully fluorinated pol)nner such as polytetrafluoroethylene. The latter has a much wider range of corrosion resistance. 

Chlorosulfonated Polyethylene Ruhher Thermosetting elastomers containing 20-40% chlorine. Has good weatherability and heat and chemical resistance. Used for hoses, tubes, sheets, footwear soles, and inflatable boats. 

Uses of Chlorinated Polyethylene Vulcanizates. CM is used in applications where aging resistance in hot air, oils, or chemicals is required and where good ozone, weathering, and flame resistance are required. Many such applications are in the wire and cable industry. 

Natural rubber in which about two-thirds of the hydrogen atoms have been replaced by chlorine atoms. The resin is formed by the reaction of rubber with chlorine at about 100° C in an inert solvent or as a latex. Unlike rubber, the resulting product is readily soluble and yields solutions of low viscosity. It is sold as white powder, fibers, or as blocks. Commercial products generally contain about 65% chlorine. It has good chemical resistance properties, however, it tends to cobweb when sprayed. Now mostly chlorinated polymers are used, as 1-butene, polyethylene, etc. It has adhesive properties and, because of its good fire resistance, is used in paints. (2) Chlorinated natural rubber. Manufactured by Bayer, Germany. 

PMMA/PVC blends provide heat resistance and chemical and flammability resistance into materials for injection moulding and extrusion applications. The major applications of these blends are interior panelling, trim and seat backs in mass transit vehicles. Commercially available PMMA is miscible with PVC [28, 31]. However, its phase behaviour is considered to be only partially miscible [29]. Chlorinated polyethylene blends with PVC have been used as impact modifiers and as secondary plasticisers [32], Chlorine contents of 42% and 30% by weight lead to miscible and immiscible properties, respectively. Impact modification will generally require phase separation, and plasticisation will require miscibility. 

Chlorinated plastics are polymers that have many chlorine atoms in their molec-nlar chain. Good flame resistance and chemical inertness usually characterize these materials. Examples of such materials are chlorinated polyethylene, chlorinated polyether, chlorinated polyvinyl chloride, and chlorofluorocarbons. 

Chlorinated polyethylene has inherent oxygen and ozone resistance because of the saturated nature of the polymer. It also shows exceptionally high tear strength and heat aging characteristics and excellent oil and chemical resistance. To reduce cost, the base polymer can be heavily extended with processing oils and inert filler. 

The significant advantages of products produced from chlorinated polyethylene are their improved resistance to chemical extraction, plasticizer volatility, and weathering. Products made from chlorinated polyethylene do not fog at higher use temperatures and can be made completely flame retardant. They do, however, exhibit chemical instability similar to that of polyvinyl chloride (PVC). They may be used as primary compounding materials or as blending resins with PVC, high- and low-density polyethylene, and other polymers. They are cross-linkable by irradiation or chemical means. 

Chlorinated polyethylene (CPE) modifiers have good impact resistance at low temperatures, chemical resistance, heat and light stability, and FDA clearance. These modifiers are most commonly used in pipe, fittings, siding, and weatherable profiles. CPE modifiers compete primarily with acrylics in siding applications. (See also chlorinated polyethylene.)... 

Polyethylene terephthalate is a polyester. It is a Unear ester composed of ethylene glycol and terephthalic acid. PET has excellent mechanical characteristics it is for example pressure- resistant. The chemical resistance is good compared to other plastics. PET is not resistant to strong alkali and limited resistant to strong acids and chlorinated hydrocarbons (see Table 24.2). 

Chlorosulfonatedpolyethylene (CSM) is well known under its common trade name Hypalon. It is prepared by reacting polyethylene with sulfur dioxide and chlorine. This elastomer has outstanding chemical resistance to oxidizing environments including ozone, but it is readily attacked by fuming nitric and sulfuric acids. It is oil-resistant but it has poor resistance to aromatic solvents and most fuels. Except for its excellent resistance to oxidizing media, its physical and chemical properties are similar to that of neoprene with however improved resistance to abrasion, heat and weathering. 

This family of elastomers is produced by the random chlorination of HDPE (the proprietary Tyrin is from Dow Chemical). The properties of chlorinated polyethylene (CM) include excellent ozone and weather resistance, heat resistance to 149°C (300°F) and even 177°C (350°F) in many types of oil, dynamic flex resistance, and resistance to abrasion. 

---