Polyvinyl Chloride or PVC is the most practical synthetic plastic polymer after polyethylene and polypropylene. PVC is produced in two different forms. It can be rigid which is called RPVC and used in pipes and profiles like doors and windows. It also can be made more flexible to be used in flooring, signage, plumbing, electrical cable insulation ….

PVC’s hardness is high. Its mechanical properties increase by the molecular weight increase and it will decrease by the temperature increase. Since the row PVC’s stability in heat is poor, it is necessary to use heat stabilizer during the thermal processes. Adding enough amount of stabilizer can increase the melting temperature of the PVC up to 260°C (500° F).

PVC can be suitable to be used for insolation of medium or low voltage materials. As PVC is resistant to different chemical substances like acids, salts, bases, fats and alcohols, it will be resistant to corrosive effects of sewage and can be used in sewage piping networks.

PVC is one of the most used materials in cities water and sewage networks. It is used in building industry as window frames and flooring materials. Its plasticized form is used as insulation on electrical cables. Also it can be used as a weather resistant material in clothing industry to make coats, jackets, skiing equipment, shoes and sport bags.

Polystyrene (PS) plastic is a naturally transparent thermoplastic that is available in two different forms: as a typical solid plastic and a rigid foam material. PS can be easily converted to semi-finished products like foams, films and sheets. It is a good electrical insulator and has good chemical resistance to diluted acids and bases. Since it doesn’t have any crystal in its structure, it has a good optical clarity.

Although its’ various properties, it has many limitations. For example It is attacked by hydrocarbon solvents, has poor oxygen and UV resistance, and is rather fragile, i.e. because of the stiffness of the polymer backbone, it has poor impact strength. Furthermore, because of the non-crystal structure temperature limit and low glass transition temperature (Tg) , its upper temperature limit for continual use is low. Below its Tg, it has medium to high tensile strength (35 – 55 MPa) but low impact strength (15 – 20 J/m). Despite all these weaknesses, styrene polymers are very attractive large-volume commodity plastics.

There are Three major types of polystyrene: polystyrene foam, regular polystyrene plastic, and polystyrene film. expanded polystyrene (EPS) includes the most well-known and common types of polystyrene to include styrofoam and packing peanuts. EPS specifications are as follow:

• High thermal insulation
• Resistant to Moisture
• Extremely durable
• Easily recyclable
• Versatile in strength
• Easily laminated with epoxy resin
• Manufactured into different shapes, sizes, and compression materials
• Lightweight and portable
• High shock absorbency characteristics
• Compression resistant
• Branded by printing or adhesive labeling.
• Completely recyclable

Also it has some disadvantages like:

• Not resistant to organic solvents
• Cannot be used in combination with MPVC hydro-insulation foils
• Previously, EPS was made from Chlorofluorocarbons which damaged the ozone layer
• Flammable if oil painted
• Health concerns with styrene chemicals seeping into hot beverages or food placed in EPS cups

Polypropylene (PP) is a linear hydrocarbon which belongs to polyolefin family of polymers. It is shown as CnH2n. It can be used as plastic or fiber in different industries like automotive, consumer goods and furniture. Propylene in made by polymerization of propene monomer which can be achieved at low temperature and pressure. In compare with polyethylene, PP has lower density, higher rigidity and higher softening points. There are three different types of PP with different prices and specifications: Homopolymers, Random Polypropylene copolymers and Block copolymers.

Polypropylene Homopolymers is the most used type and contains only propylene monomer in a semi-crystalline solid form. It is used in packaging, textiles, healthcare, pipes, automotive and electrical applications.

Random copolymers – Polypropylene Random Copolymer is produced by polymerizing together ethene and propene. It features Ethene units, usually up to 6% by mass, incorporated randomly in the polypropylene chains. Such polymers typically are selected where a lower melting point, more flexibility and enhanced clarity are advantageous.

Block copolymers – in Polypropylene Block Copolymer, ethene content is larger (between 5 and 15%). It has co-monomer units arranged in regular pattern (or blocks). The regular pattern hence makes thermoplastic tougher and less brittle than the random co-polymer. These polymers are suitable for applications requiring high strength, such as industrial usages.

Polypropylene specifications should be considered while choosing a thermoplastic for an application.

Melting point : Homopolymer: 160-165°C / Copolymer: 135-159°C

Density: In comparison with all commodity plastics, PP is one of the lightest polymers. Density of three polypropylene are:

Homopolymer: 0.904 – 0.908 g/cm3

Random Copolymer: 0.904 – 0.908 g/cm3

Impact Copolymer: 0.898 – 0.900 g/cm3

Flammability: Polypropylene is a highly flammable material

retains mechanical & electrical properties at elevated temperatures, in humid conditions and when submersed in water. It is a water-repellent plastic

PP has good resistance to environmental stress cracking, It is sensitive to microbial attacks, such as bacteria and mold, It exhibits good resistance to steam sterilization

Polypropylene Chemical Resistance: Excellent resistance to diluted and concentrated acids, alcohols and bases,Good resistance to aldehydes, esters, aliphatic hydrocarbons, ketones,Limited resistance to aromatic and halogenated hydrocarbons and oxidizing agents

Disadvantages of Polypropylene:

Poor resistance to UV, impact and scratches, Embrittles below -20°C

Low upper service temperature, 90-120°C

Attacked by highly oxidizing acids, swell rapidly in chlorinated solvents and aromatics Heat-aging stability is adversely affected by contact with metals

Post molding dimensional changes due to crystallinity effects – this can be solved with nucleating agents

Poor paint adhesion

PET is a multipurpose thermoplastic polymer from the polyester family which can be used in different mechanical, thermal, chemical resistance properties. This polymer is produced by polymerization of ethylene glycol and terephthalic acid. Ethylene glycol is a colorless liquid obtained from ethylene, and terephthalic acid is a crystalline solid obtained from xylene. By heating them together with chemical catalysts, molten viscous masses of PET will be obtained that can be converted to fibers.

This product can be processed as plastic. PET is mainly used as a packaging material in recycling bins, bottles and packaging consumer goods like  soft drinks, alcoholic beverages, detergents, cosmetics, pharmaceutical products and oils. Also it can be used to make water resistant papers.

Low-density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene. It was the first grade of polyethylene, produced in 1933 by Imperial Chemical Industries (ICI) using a high pressure process via free radical polymerization. LDPE has the most excessive branching.

This causes the low density to have a less compact molecular structure which is what makes it less dense. It has a density of 0.91-0.925g/cm3. Linear Low Density Polyethylene (LLDPE) is the most flexible of the plastic sheeting films. LLDPE is blended form of LDPE where the film has much more flexibility, tensile strength, and more conformability. It is more pliable and softer.

LLDPE has a significant number of short branches. Because it has shorter and more branches its chains are able slide against each other upon elongation without becoming entangled like LPDE which has long branching chains that would get caught on each other. This gives LLDPE higher tensile strength and higher impact and puncture resistance than the LDPE. It has a density of 0.91-0.94g/cm3.

LLDPE is used for pond liners or blended into other films to give them more flexibility and extra strength. LLDPE is used for films that need a tremendous amount of strength to absorb impacts while not tearing or puncturing. An example of this is a carpet plastic film that adheres to the carpet.

It is strong enough to withstand foot traffic, even from stiletto high heels! The molecules all line up and strongly hold together as the film is stretched. The most common thickness range is from 0.5 mil to 40 mil in flexible plastic sheeting.

High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. Not only is it one of the most versatile of plastics—used in everything from hard hats to house wraps—it’s also widely recycled, in both its rigid form (e.g., containers) and flexible form (e.g., bags). Like many other plastics, HDPE often replaces heavier materials, in part because our society and many companies are pursuing sustainability goals, such as reducing the amount of material used in packaging and products.