First, PP is an environmentally friendly material.

Second, the difference between PP and PVC can be clearly distinguished in terms of appearance and feel; 

PP feels harder while PVC is relatively soft. The best way to test is to burn the two materials with an open

 flame. If there is black dust, PVC but not PP. It can also be distinguished from the smell. PVC has a pungent

 smell, while PP is odorless.

PVC (polyvinyl chloride) and PP (polypropylene) have different monomers.

Identified by combustion identification method:

PP burns easily, melts and drips, and the burning flame state is yellow at the top and blue at the bottom 

with less smoke. It continues to burn after leaving the fire and smells of petroleum.

PVC is difficult to burn, melts and softens, the burning flame state is yellow at the top and green at the 

bottom with smoke, extinguishes when it is away from the fire, and has a pungent sour smell.

PP

A thermoplastic resin produced by polymerizing propylene. There are three configurations: isotactic, atactic

 and syndiotactic. Industrial products have isotactic as the main component. Polypropylene also includes 

copolymers of propylene and a small amount of ethylene. It is usually a translucent colorless solid, odorless 

and non-toxic. Due to its regular structure and high degree of crystallization, its melting point is as high as

 167°C. It is heat-resistant and its outstanding advantages are that the product can be sterilized by steam. 

With a density of 0.90g/cm3, it is the lightest general-purpose plastic. Corrosion resistance, tensile strength 

30MPa, strength, rigidity and transparency are better than polyethylene. The disadvantage is that it has poor

 low-temperature impact resistance and is prone to aging, but this can be overcome by modification and

 addition of antioxidants.

Features:

Non-toxic, tasteless, low density, strength, stiffness, hardness and heat resistance are better than low-pressure 

polyethylene, and can be used at around 100 degrees. It has good electrical properties and high-frequency 

insulation and is not affected by humidity, but becomes brittle at low temperatures. , not wear-resistant, easy

 to age. Suitable for making general mechanical parts, corrosion-resistant parts and insulating parts. Common

 acid and alkali organic solvents have almost no effect on it and can be used in tableware.

Combustion characteristics:

It is flammable and will continue to burn after being removed from the fire. The upper end of the fire will be

 yellow, the lower end will be blue, and there will be a small amount of black smoke. It will dissolve and drip

 when burning. It will also emit a petroleum smell.

Injection molding temperature 190-240.

PVC

It is one of the most produced plastic products in the world. It is cheap and widely used. PVC resin is white or

 light yellow powder. Different additives can be added according to different uses, and PVC plastic can exhibit

 different physical and mechanical properties. By adding an appropriate amount of plasticizer to PVC resin, a 

variety of hard, soft and transparent products can be made.The density of pure polyvinyl chloride is 1.4g/cm3, and the density of polyvinyl chloride plastic parts with

 plasticizers and fillers added is generally 1.15-2.00g/cm3.

Rigid polyvinyl chloride has good tensile, bending, compression and impact resistance, and can be used alone

 as a structural material.

The softness, elongation at break, and cold resistance of soft PVC will increase, but the brittleness, hardness, 

and tensile strength will decrease.

Polyvinyl chloride 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 cause the polyvinyl chloride to change color. Therefore, its 

application range is narrow, and the use temperature is generally between -15 and 55 degrees.

PVC is refractory to fire and extinguishes immediately after leaving the fire. However, when it burns, the upper

 end of the flame will be yellow and the lower end will be green, with white smoke. When burning, the rubber 

will become soft and emit the pungent smell of hydrochloric acid. PVC is slightly toxic, but there are also 

food-grade PVC. .

The English abbreviation of PVC polyvinyl chloride. There are two types: hard and soft. Divided into two 

categories: poisonous and non-toxic. The hard plastic used in household life is basically PVC. Such as water

 pipes and wire sheaths. PP polypropylene. Plastic carbonated drink bottles are all made of PP (cola) and can 

withstand a little pressure. There is also a tool box whose bottom and lid are integrated and can be opened

 and closed repeatedly without hinges. This material must be PP.