1. Different physical properties
PVC: It has stable physical and chemical properties, is insoluble in water, alcohol, and gasoline, and has low gas and water vapor leakage; it can withstand any temperature at room temperature. The concentration of hydrochloric acid, sulfuric acid below 90%, nitric acid between 50-60% and caustic soda solution below 20% has certain resistance to chemical corrosion; it is quite stable to salts, but can be dissolved in ethers, ketones, and chlorinated aliphatic hydrocarbons and aromatic hydrocarbons and other organic solvents.
PP: Polypropylene is a non-toxic, odorless and tasteless milky white highly crystalline polymer with a density of only 0. 90--"0. 91g/cm3. It is the lightest variety of all plastics at present. 1. It is particularly stable in water, with a water absorption rate of only 0.01% and a molecular weight of about 80,000 to 150,000.
It has good moldability, but due to its large shrinkage (1%~ 2.5%). Thick-walled products are easy to dent, and it is difficult to meet the requirements for some parts with high dimensional accuracy. The surface of the product has good gloss.
2. Different characteristics
PVC: polychloride. Ethylene has flame retardancy (flame retardant value is above 40), high chemical resistance (resistant to concentrated hydrochloric acid, 90% sulfuric acid, 60% nitric acid and 20% sodium hydroxide), mechanical strength and electrical resistance. Advantages of good insulation.
PP: non-toxic, odorless, low density, strength, stiffness, hardness and heat resistance are better than low-voltage polyethylene, and can be used at around 100°C. It has good performance and high-frequency insulation and is not affected by humidity, but it becomes brittle at low temperatures, is not wear-resistant, and is easy to age. It is suitable for making general mechanical parts, corrosion-resistant parts, and insulating parts. Common organic solvents such as acids and alkalis are almost insensitive to it. Does not work, can be used for tableware
3. Different applications
PVC: Stabilizers, lubricants and fillers are added to PVC, and after mixing, it can be used with an extruder. Extrude hard pipes, special-shaped pipes, and corrugated pipes of various diameters and use them as sewer pipes, drinking water pipes, wire casings, or stair handrails.
The rolled sheets can be overlapped and hot-pressed to make various shapes. Rigid plates of various thicknesses can be cut into required shapes and then welded with hot air using PVC welding rods to form various chemical corrosion-resistant storage tanks, air ducts and containers.
Use extrusion. The machine can be extruded into hoses, cables, wires, etc.; the injection molding machine can be used with various molds to make plastic sandals, soles, slippers, toys, auto parts, etc.
PP: household appliances, plastics. Pipes, high-permeability materials, etc.
Baidu Encyclopedia-Polyvinyl Chloride
Baidu Encyclopedia-Polypropylene