HDPE and PVC are the two most common plastics in the market, and both are widely used. Which of these two plastics has more advantages?
PVC
Scientific name: polyvinyl chloride, is a kind of non-crystalline material, is vinyl chloride monomer (VCM for short) in peroxide, azo compound and other initiators; or by free radical polymerization under the action of light and heat The reaction mechanism is a polymer formed by polymerization.
PVC is a white powder with an amorphous structure, the degree of branching is small, the relative density is about 1.4, the glass transition temperature is 77~90°C, it begins to decompose at about 170°C, and it has poor stability to light and heat. When exposed to sunlight, it will decompose to produce hydrogen chloride, and further autocatalyze the decomposition, causing discoloration and rapid decline in physical and mechanical properties. In practical applications, stabilizers must be added to improve the stability to heat and light.
Main features:
Strong corrosion resistance, most suitable for anti-corrosion equipment in the chemical industry.
Easy processing: cutting, welding and bending are all very simple. High strength, high rigidity and high hardness;
Good electrical insulation; good chemical stability; self-extinguishing;
low water absorption;
Easy to bond, easy to paint. Inexpensive.
Disadvantages: poor fluidity, easy to decompose, decomposition will produce pungent smell, working temperature range from minus 15 degrees to 60 degrees.
Main applications: Acid test manufacturing tower, seawater concentration tank, photo developing equipment, electroplating tank, battery box, electric meter board, audio seat cover, radio bottom plate, various electrical insulation boards, cement tank lining, machine windshield, Exhaust air duct engineering engineering, stationery, building materials, etc.
HDPE
Scientific name: high-density polyethylene, non-toxic, tasteless, crystallinity of 80% to 90%, softening point of 125 to 135°C, service temperature up to 100°C; good wear resistance, electrical insulation, toughness and cold resistance ; Good chemical stability, insoluble in any organic solvent at room temperature, resistant to acid, alkali and various salts;
Main features:
Has excellent corrosion resistance properties;
Non-hygroscopic and has good water vapor resistance;
High dielectric strength of insulation;
Good machinability and heat sealability;
Good self-lubrication;
It is non-toxic and odorless, and can also be used for packaging materials such as food, clothing, and knitwear;
Modifiers can be added, such as two-color HDPE sheet with anti-UV stabilizers;
Disadvantages: poor aging resistance, thermal oxidation will reduce its performance, low transparency, poor barrier to oxygen and other gases; the use temperature of HDPE is not high, generally below 100 °C.
Main applications: HDPE sheets, sewage pipes, storage tanks, wire and cable protective sleeves, bottle caps, chemical containers, drainage pipes, suitcases, ground protection mats, food-grade cutting boards, amusement equipment, etc.
From the above point of view, both are suitable for high temperature, but HDPE material is more suitable for low temperature environment exceeding minus 10 degrees. HDPE is colorless, odorless and non-toxic, can be in direct contact with food, and can be recycled for secondary use, making it more environmentally friendly.