What Are Polymeric Materials?
A polymeric material is a material composed of a compound with a molecular weight exceeding 10,000, defined as a polymeric compound. There is no clear standard for the molecular weight of a polymer.
Polymeric materials are made from low-molecular-weight monomers through a reaction (polymerization) to form polymers, and are also called polymers in the sense that they are compounds of many monomers.
Types of Polymeric Materials
There are three types of polymeric materials: natural polymers, existing man-made materials, and synthetic polymers. Polymeric materials are commonly referred to as synthetic polymers.
Synthetic polymers include polyethylene, polypropylene, styrenics, polyvinyl chloride, PET fiber, nylon fiber, engineering plastics, polyurethane, epoxy resin, acrylic resin, fluoropolymers, and specialty synthetic rubbers.
Characteristics of Polymeric Materials
Polymeric materials (synthetic polymers) are characterized by processability, light weight, and strength.
1. Processability
Compared to metals and glass, polymers can be melted at relatively low temperatures (100-200℃), dissolved in solvents, and fluid in the raw or semi-fluid state, making them easy to process during molding.
2. Lightweight
In general, specific gravity is around 1 to 1.5. The specific gravity of polyethylene and polypropylene is 0.90 to 0.97, and some materials are less than 1. The specific gravities of steel and aluminum are 7.8 and 2.7, respectively, indicating that polymeric materials are lightweight. The specific gravity of polymeric materials can exceed 2 when fillers are added to give them strength, but when they are made into foam products, the specific gravity is 0.1, etc. The weight can be varied by changing the formulation and manufacturing process according to the application.
3. Strength
There are several indicators of strength, but we will use tensile strength as an example here. Polymeric materials themselves, such as plastics and rubbers, are not as strong as metals and glass.
However, by adding fillers such as glass and carbon fibers, it is possible to increase the strength of plastics several times. Plastic materials with low specific gravity can gain strength comparable to metal materials such as steel, and in particular, carbon fiber reinforced plastic, known as FRP, has strength surpassing that of magnesium alloys and duralumin.