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Plastic acid-proof alkaline

by:CSSSLD     2021-01-23
Polycarbonate and polyamide plastics is due to hydrogen ion and hydroxide ion hydrolysis reaction catalyst, so this kind of plastic in the acid medium and under the action of alkaline medium, then easy hydrolysis reaction caused by the destruction of the molecular structure, and not easy to hydrolysis of the polymer, relatively, has good acid and alkali. Acid and alkaline of the injection molding processing with different structure and a lot of selectivity, some of them are both acid and alkali resistant, some is not acid-proof, alkali resistance and some is acid-proof not alkali resistance.

environmental stress cracking and solvent cracking is a kind of material that has nothing to do with the swelling and dissolving. The cause is due to some external reasons, inside the plastic molecules produced a result of the stress concentration of material craze. Plastic material the ability of resistance to chemical attack and physical and chemical structure of plastic, including energy, the molecular weight of polymer key type and key size, crystallinity, degree of crosslinking, chain of factors such as rigidity, also related to the type and concentration of chemical substances, in addition, the change of environmental temperature, the type and size of stress as well as the effect of the length of time is also very important influence factors.

most plastics on the oxidizing medium is not stable, especially the molecular chain oxidation weaknesses of tertiary carbon atoms, the double bond and branched polymer. Such as polyethylene, polypropylene, a class of polymers containing carbon-carbon bonds especially vulnerable to nitric acid and fuming sulfuric acid such strong oxidizing medium erosion, oxidation and undermine its molecular structure. In addition, catalyzed by alkali and acid hydrolysis reaction is another kind of common corrosion reactions. Hydrolysis reaction occurs mainly in containing ester, ether, amide, etc is sensitive to hydrolysis condensation polymer type.


some plastic at room temperature without stress under the action of the ability of resistance to chemical attack and under high temperature, the stress situation is, will be different, so the stress of some data, attention should be paid to obtain the condition of corrosion data, environment, etc. With filler filler or fiber reinforced composite materials, chemical medium for packing or fiber additive chemicals and due to the penetration of chemical substances, weaken the combination between the substrate and additive also nots allow to ignore.

although the process may be related to chemical structure of the polymer itself has no direct relationship between the change, but he can because of the nature of the polymer composition and the change of the quantity and make practical deteriorate. Improve the plastic is also one of the most important methods commonly used chemical corrosion resistance, is for a specific corrosive environment, choose appropriate corrosion resistant materials. The material can be modified if necessary. Such as the inner wall of the container of contact corrosion medium, fluoride with a fluorine plastic or other corrosion resistant plastic mixing or compound, etc.

in solvent type medium seep into the molecular internal plastic injection tooling, weaken the forces between molecular chains, which is the destruction of the valence bond as a condition for characteristics. The result is physical swelling and dissolving, weight, size, appearance change, and the decrease of mechanical properties. Swelling and dissolving was change of form, and after the solvent evaporation and basic recovery, but the change is difficult to allow in practical.

plastic at room temperature to the low concentration of acid and alkali are generally used in industry have good erosion resistance, but at high temperature, high concentration of acid and alkali, for most of the plastic, have very strong reactivity. Polymer molecular chain with various groups, like all the low molecular compound, can according to the basic rule of organic chemistry, halogenation, nitration, sulfonated with corrosive medium, etherification, such as chemical reaction, so in comparison, the polymers with reactive group, far worse, chemical corrosion resistance and without polymer with polar group, and generally have good resistance to chemical corrosion.

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