PVC， The full name is polyvinyl chloride, which is a common thermoplastic widely used in various industries. 

The following is a comprehensive introduction to PVC:

1. Structure and Properties

Chemical structure:

PVC is formed by free radical polymerization of vinyl chloride monomer (VCM). Its molecular formula is (C2H3Cl) n, where n represents the number of repeating units.

physical property:

Appearance: PVC is usually a white or pale yellow powdery solid.

Density: Approximately 1.35-1.45 g/cm ³.

Melting point: Approximately between 100-260 ° C, depending on the molecular weight of the polymer and the type of plasticizer.

Mechanical properties:

Hardness:Unplasticized PVC (UPVC) is very hard, while plasticized PVC (PVC-U) has a certain degree of flexibility.

Strength: Has high tensile strength and impact resistance.

Chemical resistance: It has good corrosion resistance to most acids, alkalis, and salts.

2. Types and modifications

According to different plasticizers, PVC can be divided into the following types:

Hard PVC (UPVC/Rigid PVC): does not contain or contains a small amount of plasticizers, has high rigidity and chemical resistance, and is commonly used in fields such as construction and pipelines.

PVC-U/Flexible PVC: Contains a large amount of plasticizers such as phthalates (DOP, DEHP), which have good flexibility and elasticity, and are commonly used in fields such as wires and cables, medical supplies, etc.

Common modification methods include:

Blending modification: Mixing with other polymers to improve certain properties such as impact resistance, heat resistance, etc.

Filling modification: Adding inorganic fillers (such as calcium carbonate, talc powder, etc.) to reduce costs, improve hardness and heat resistance.

Co polymerization modification: By copolymerizing other monomers (such as vinyl acetate, acrylic ester, etc.), the processing and physical properties of PVC are improved.

3. Processing technology

The processing technology of PVC mainly includes the following steps:

Drying: Due to the strong hygroscopicity of PVC powder, it needs to be dried before processing.

Plasticization: By heating and shearing, PVC powder is transformed into a melt with certain fluidity.

Extrusion: The plasticized PVC melt is passed through an extruder head to form various shapes of products, such as pipes, sheets, etc.

Molding: Using molds or rolling machines to shape PVC melt into the desired shape.

Cooling and shaping: The molded product is cooled to solidify and maintain its shape.

4. Application Fields

PVC is widely used in various industries due to its excellent performance and low cost

Building materials: doors and windows, pipes, floors, wall panels, etc.

Packaging materials: bottle caps, films, packaging boxes, etc.

Medical supplies: blood transfusion tubes, gloves, urinary catheters, etc.

Electronic products: wires and cables, circuit board substrates, etc.

Automotive industry: interior parts, sealing strips, tires, etc.

Agriculture: agricultural film, irrigation pipelines, etc.

5. Environmental Protection and Recycling

PVC, as a plastic material, has attracted much attention for its environmental friendliness and recycling:

Environmental friendliness: PVC itself is non-toxic, but harmful substances such as vinyl chloride monomer may be produced during the production process. In addition, burning PVC produces toxic gases such as hydrogen chloride.

Recycling: PVC has good recyclability, and through steps such as cleaning, crushing, and reprocessing, waste PVC products can be reused to reduce environmental pollution.

6. Development Trends

The future development trend of PVC mainly focuses on the following aspects:

Green production: Developing low pollution and low-energy production processes to reduce environmental impact.

High performance: Through modification technology, the heat resistance, impact resistance and other properties of PVC are improved, expanding its application fields.

Functionalization: Develop PVC materials with special functions, such as antibacterial PVC, conductive PVC, etc., to meet specific needs.

I hope this information is helpful for you to understand PVC! If you have any further questions or need further information, please feel free to let me know.