Pro-Fax Polypropylene Chemical Resistance

Pro-fax polypropylene, like most of the polyolefins, is highly resistant to solvents and chemicals. The results of extensive laboratory and actual field installation tests of polypropylene's chemical resistance are reported in this data sheet, which is updated at intervals.

The corrosion resistance data presented here are based on unstressed specimens of Pro-fax resins, 3 in. long by 0.025 in. thick, in the shape of dumbbells. Results are reported after 1-month immersion. As it is difficult to create actual service conditions in the laboratory, the results of many of the environments should be taken only as an indication of behavior in service.

Pro-fax polypropylene has outstanding resistance to water and other inorganic environments. In most aqueous environments, its weight increase is less than 0.2% when it has been stored for 6 months at ambient temperatures. When the temperature is increased to 60° C (l40" F), the weight increase is less than 0.5% for a similar period. According to ASTM D 570-63T, its 24 hr. water absorption rate is 0.03%. It resists most strong mineral acids and bases, but, like the other polyolefins, it is subject to attack by oxidizing agents.

Pro-fax polypropylene is appreciably affected by chlorosulfonic acid and oleum at room temperature, 98% sulfuric acid, 30% hydrochloric acid and 30% hydrogen peroxide at 100° C (212°F), It is also affected by 98% sulfuric acid at 60° C (140° F) and fuming nitric acid and liquid bromine at room temperatures. Under strain, failure could occur with strong oxidizing acids at temperatures lower than those mentioned. With few exceptions, however, inorganic chemicals produce little or no effect on Pro-fax resin over a period of 6 months at temperature up to 120° C (248)° F).

The permeation resistance of Pro-fax polypropylene to organic chemicals depends on the rate and extent to which absorption occurs.

This, in turn, will govern the suitability of the resin to serve in a particular environment. When the plastic is removed from the environment, evaporation will take place and cause it to return almost to its original dimensions. Property changes resulting from the absorption will be reversed if evaporation is complete.

Temperature and polarity of the organic medium are the foremost factors determining the extent of absorption by polypropylene. Absorption becomes greater as temperatures are increased and polarity of the medium is decreased. Copolymers swell more than homopolymers, indicating greater absorption. Such nonpolar liquids are benzene, carbon tetrachloride, and petroleum either have a higher absorption rate by polypropylene than polar media such as ethanol and acetone. Some reduction in tensile strength and an increase in flexibility and elongation to break in tension can be expected, depending on the nature and amount of the organic medium absorbed.

Pro-fax polypropylene has excellent resistance to environmental stress cracking. When it is tested according to ASTM D 1693-60T, the brittle fractures that occur with certain polyethylenes in contact with polar organic liquids, detergents, and silicone fluids are not observed. Failure of this type with polypropylene is rare. Those environments known to cause such cracking to polypropylene are 98% sulfuric acid, concentrated chromic/sulfuric acid mixtures, and concentrated hydrochloric acid/chlorine mixtures.

The useful life of Pro-fax polypropylene at elevated temperatures is limited by oxidative degradation. The expected life of polypropylene at any given temperature is also determined by the nature of the environment, and by the extraction of some of the antioxidant system. Any environment that tends to extract the antioxidants may lead to more rapid breakdown of the polypropylene, especially at elevated temperatures.

Rating System
This chart rates the chemical resistance of Pro-fax polypropylene according to the following code:

A = Negligible Effect - Should be suitable for all applications where these environmental conditions exist.

B = Limited absorption or Attack - Should be suitable for most applications, but the user is advised to make his own tests to determine the suitability of polypropylene in the particular environment

C = Extensive Absorption and/or Rapid Permeation - Should be suitable for applications where only intermittent service is involved, or where the swelling produced has no detrimental effect on the part. The user should make his own tests to determine the suitability of polypropylene in the particular environment.

D = Extensive Attack - the specimen dissolves or disintegrates. Polypropylene is not recommended.

Pro-fax polypropylene chemical resistance chart 1.

Pro-fax polypropylene chemical resistance chart 2.

Pro-fax polypropylene chemical resistance chart 3.

Pro-fax polypropylene chemical resistance chart 4.

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Pro-fax polypropylene chemical resistance chart 6.