I believe everyone knows that PP sheet and pvc sheet are both widely used sheet materials, but the two have many different advantages, which we need to understand when processing.
>> PP sheet is an environmentally friendly material
>> Difference between PP sheet and PVC sheet
1. PP sheet feels harder, while PVC is relatively soft. The best test method is to burn these two materials with an open flame, and the black dusty one is PVC. It can also be distinguished from the smell, PVC has a choking smell, while PP is tasteless.
2. The monomers of PVC (polyvinyl chloride) and PP (polypropylene) are different.
>> Identification by combustion identification method
1. PP is easy to burn, melts and drips, and the burning flame state is that the upper yellow and the lower blue smoke are less, and it continues to burn after leaving the fire, and it has a petroleum smell.
2. PVC is difficult to burn, melts and softens, and the burning flame state is yellow on top and green on the bottom with smoke, extinguished from fire, and pungent and sour.
3. PP sheet is a thermoplastic resin obtained by polymerizing propylene. There are three configurations of isotactic, random and syndiotactic, and industrial products are mainly composed of isotactic. Polypropylene also includes copolymers of propylene with small amounts of ethylene. Usually translucent colorless solid, odorless and nontoxic.
Due to the regular structure and high crystallization, the melting point is as high as 167 °C. Heat resistance, the product can be sterilized by steam is its outstanding advantage. With a density of 0.90g/cm3, it is the lightest general-purpose plastic. Corrosion resistance, tensile strength of 30MPa, strength, rigidity and transparency are better than polyethylene.
The disadvantage is that it has poor low temperature impact resistance and is easy to age, but it can be overcome by modification and addition of antioxidants respectively.
>> Characteristics of PP sheet and PVC sheet
1. PP sheet is non-toxic, tasteless, low density, and its strength, stiffness, hardness and heat resistance are better than low pressure polyethylene, and can be used at about 100 degrees Celsius. PP has good electrical properties and high frequency insulation, and is not affected by humidity. But it becomes brittle at low temperature, not wear-resistant and easy to age. Suitable for making general mechanical parts, corrosion-resistant parts and insulating parts. Common acid and alkali organic solvents have little effect on it, and can be used for tableware.
2. Combustion characteristics of PP sheet: It is flammable and will continue to burn after leaving the fire. The upper end of the flame is yellow and the lower end is blue, with a small amount of black smoke. It melts when burned and emits a petroleum odor. The injection temperature of PP sheet is 190-240 degrees.
3. PVC It is one of the plastic products with the largest output in the world. It is widely used because of its low price. Polyvinyl chloride resin is white or light yellow powder, and different additives can be added according to different uses. PVC plastics can exhibit different physical and mechanical properties. Adding an appropriate amount of plasticizer to polyvinyl chloride resin can make a variety of hard, soft and transparent products.
4. The density of pure PVC is 1.4g/cm3, and the density of PVC plastic parts with plasticizers and fillers is generally 1.15-2.00g/cm3.
5. Rigid PVC has good tensile, bending, compressive and impact resistance, and can be used alone as a structural material.
6. The softness, elongation at break and cold resistance of soft PVC will increase. But brittleness, hardness, and tensile strength will be reduced.
7. PVC has good electrical insulation properties, can be used as low frequency insulation material, and its chemical stability is also good. Due to the poor thermal stability of polyvinyl chloride, long-term heating will cause decomposition, release HCL gas, and make polyvinyl chloride discoloration, so its application range is narrow, and the operating temperature is generally between 15 and 55 degrees.
8. PVC is incombustible, and it will be extinguished when it is removed from the fire. But when burning, the upper end of the flame is yellow, the lower end is green, and there is white smoke. When burning, the compound becomes soft and emits a pungent odor of hydrochloric acid. PVC is slightly toxic, but there are also food grade PVC.
9. PVC is divided into two categories: toxic and non-toxic. The hard plastic used in domestic life is basically PVC. Such as water pipes, wire sheath.
Plastic carbonated beverage (Coke) bottles are made of PP sheets, which can withstand a little pressure.
There is a kind of toolbox in life. The bottom and the cover are one piece, and it can be opened and closed repeatedly without hinges. This material must be PP sheet.