Chlorinated polyether

(1) Introduction to chlorinated polyethers
Chlorinated polyether is also known as polychloride ether, abbreviated as CP in English. Chlorinated polyether has chemical corrosion resistance second only to F4, excellent wear resistance and heat resistance, balanced mechanical properties, and high dimensional stability. It is mainly used for chemical anti-corrosion, mechanical parts and insulating materials in wet conditions.
Since the price of CP is higher than that of general-purpose plastics, its development is limited.
(2) Structural properties of chlorinated polyether
1. Structure The chemical structure of the macromolecular backbone of CP is regular and symmetrical, which shows high melting point and crystallinity, extremely low water absorption and good barrier.
2. Outstanding corrosion resistance The corrosion resistance of CP is second only to F4 in plastics, and the price is much lower than F4. Its corrosion resistance is similar to that of metal nickel and F3, except for a few strong acids, strong oxidants and strong polar solvents such as oleum acid, fuming nitric acid, dichloroethane, tetrahydrofuran and chromic acid, etc., which can corrode it to varying degrees, and is stable to a variety of acids, alkalis and solvents.
3. Excellent wear resistance and low friction coefficient CP has excellent wear resistance, which is 2 times that of PA6, 3 times that of PA66, 5~6 times that of EP, and 17 times that of F3, which is one of the best engineering plastic varieties with the best wear resistance.
4. Low water absorption and good dimensional stability The water absorption rate of CP at room temperature for 24h is only 0.01% of the body, which is the smallest among engineering plastics. Its molding shrinkage rate is 0.4%~0.6%, and the dimensional stability is good, especially in applications with large humidity changes.
5. Balanced mechanical properties In addition to the low impact strength, other mechanical properties of CP are more balanced. The mechanical properties are greatly affected by factors such as crystallinity, crystal form and temperature. With the increase of crystallinity, tensile strength and flexural strength increase, while impact strength and elongation at break decrease. Tensile strength and flexural strength decrease with increasing temperature, for example, at 120°C, the tensile strength is only half that of room temperature.
CP has good creep resistance under low temperature load, generally less than 5%, which is better than PE, PVC, ABS.
6. Good heat resistance CP can be used for a long time at a temperature of 120 °C, and the short-term use temperature is in the range of 130~140 °C, showing obvious brittleness at -40 °C. Its thermal conductivity is one-third lower than that of LDPE.
7. Good electrical properties In addition to the slightly larger dielectric loss, the electrical properties of CP are similar to those of PC, which is a good insulating material, especially suitable for humid and corrosive environments. The electrical properties of CP vary greatly with temperature, but not much with frequency.
(3) Molding and processing of chlorinated polyether
1. Processing characteristics
(1) The melt viscosity of CP is low, the processing fluidity is good, its rheology is a non-Newtonian fluid, and the viscosity is very sensitive to the shear rate, which is basically similar to PE.
(2) The three crystalline forms of CP vary with different processing conditions. If the mold temperature is higher than 120°C, it is mainly α crystal form, below 120°C, it is mainly β crystal form, and when the mold temperature is higher than 120°C, it is mainly amorphous when it is cooled suddenly.
(3) CP crystallization speed is slow, the molecular flexibility is large, so the internal stress of the product is small, no post-treatment, and is suitable for the insertion of metal inserts and the production of products with complex shapes.
(4) The water absorption of CP is small, and it can be processed directly without drying.
(5) CP is easy to release corrosive gas during processing, and the barrel and screw of the processing equipment should be chrome-plated and anti-corrosion.
2. Processing method
CP can be processed by injection molding, extrusion, blow molding and molding.
(4) Application range of chlorinated polyether
(1) In terms of chemical anti-corrosion, CP can be used in corrosive environments below 120 °C, instead of stainless steel and F4 materials, mainly to make anti-corrosion coatings and corrosion-resistant products, such as acid, alkali and organic solvent resistant pump shells, valves, chemical pipelines and containers.
(2) In terms of machinery, due to the advantages of good wear resistance, small creep, dimensional stability and no internal stress, CP can be used for mechanical parts and instrument accessories, including bearings, bearing cages, guide rails, gears, cams, racks, shaft sleeves and sealing materials.
(3) In the electrical industry, CP can be used as an insulating material in wet and corrosive environments, such as submarine cables, chemical cables, electrical accessories working in subtropical and salt spray environments, etc.
(4) In terms of medical devices, CP has no physiological side effects on the human body, and can be heated and sterilized by high-pressure steam, so it can be used for surgical medical devices. ◆