Plastics- Properties of plastics

Plastics consist of macromolecular organic components. In technical terms, they are known as organic polymers, however they are also commonly referred to as plastic.
Plastics are also informally referred to as plastic; however, for historical reasons, this term is more likely to be linked with poor material qualities and inferior quality.

Structure of plastics

Plastics are substances made up of molecular chains (polymers) that can be either linear, branching, or cross-linked. Their lengths range from a few thousand polymeric molecule units to more than a million. The molecular chains are made up of repeating basic units (monomers). Plastics are classified into three types based on how the polymer chains interact.

History of origin

Plastics’ history dates over more than a century. While this new class of substances was initially overlooked and treated as a low-cost replacement for metal and wood, plastics are today regarded as one of the most essential materials in industry. Throughout the previous 50 years, both the number and quality of plastics have improved substantially.

Properties of plastics

Plastic density ranges from 0.8kg per dm³ for polymethylpentene to 2.2kg per dm³ for polytetrafluoroethylene. This means that plastics are generally lighter than metals, making them appropriate for lightweight construction materials. Because of their low specific weight, plastics are commonly utilized in vehicle building, the aircraft industry, and weight-saving packaging such as PET bottles.

Plastics are flexible

Plastics’ modulus of elasticity and mechanical strength vary widely. The range of flexible qualities includes soft rubber, as well as metals, which have relatively limited flexibility. Plastics outperform all other types of materials in terms of flexibility.
Elastomers, for example, are dimensionally stable yet elastically malleable plastics that work exceedingly well as sealing materials. Because of their characteristics, they are also employed in tires and rubber bands.

Plastic requires low processing temperatures

While plastics can be processed at ambient temperature, processing them requires temperatures as high as 300°C. Processing possibilities in very low temperature ranges make production methods like thermoforming, extrusion, and injection molding reasonably straightforward and, thus, economical. Furthermore, a range of frequently heat-sensitive color pigments, fibers, processing aids, stabilizers, blowing agents, and fillers can be added thanks to the low processing temperatures.

Plastics have low thermal conductivity

Plastic has a thermal conductivity that ranges from 0.1 to 0.8 W/mK, while metals have a relatively high thermal conductivity—steel, for example, is 50 W/mK. For this reason, one of the most crucial materials for thermal insulation is plastic. Vacuum integration into the material, for instance, can improve the insulating efficacy of PS and PUR foams. Construction and automobile manufacturing are two industries that use plastic components that insulate against heat, such as VIP-Vaccum, or vacuum insulated panels.

Plastics have low electrical conductivity

The electrical volume resistance R of homogeneous plastic is in a range from 1010 to 1018 and is therefore over 15 times stronger than that of the worst-conducting metal, constantan. Consequently, plastics such as PVC, PET and ABS are particularly used to produce insulators for electrical cables.

Plastics are chemically resistant

The majority of plastics are resistant to practically all acids and to corrosion. This feature allows for a multitude of applications, such as in toys and home appliances. Plastics can, however, be dissolved in organic solvents like THF, n-heptane, 1,3-dioxolane, or dichloroacetic acid if necessary.

Many plastics are environmentally friendly

Many plastics can be recycled, which allows for reuse and makes them an environmentally benign material. Furthermore, the majority of plastics have a high calorific value and are very flammable. Because of this, thermal recycling is particularly appropriate for all plastics. Furthermore, the energy needed to make and process plastic is not very high.

Properties & use of plastics

The selection of the starting material, the production process, and the inclusion of different additives can all significantly alter the technical features of plastics. This implies that a broad range of properties, including as elasticity, temperature resistance, breaking strength, and hardness, can be generated in plastics. This implies that plastics can be turned into a large range of items for the industry. Pipes, thermal insulation, seals, textile fibers, floor coverings, paints, adhesives, cosmetics, molded parts, housings, packaging materials, and a host of other items are examples of typical plastic products.