Thermoplastic injection molding is the most common way to manufacture parts. Thermoplastics are polymers that can be repeatedly molten or softened by heating and solidified by cooling-as a physical change rather than a chemical change that takes place during the creation of thermoset materials. It is important to distinguish what type of thermoplastic should be used for the type of product you want us to help you create. Below are the most common thermoplastics used in injection molding.
Acrylonitrile Butadiene Styrene
ABS is a terpolymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene. The proportions can vary from 15 to 35% acrylonitrile, 5 to 30% butadiene and 40 to 60% styrene. The result is a long chain of polybutadiene criss-crossed with shorter chains of poly(styrene-co-acrylonitrile). The nitrile groups from neighboring chains, being polar, attract each other and bind the chains together, making ABS stronger than pure polystyrene. The styrene gives the plastic a shiny, impervious surface. The polybutadiene, a rubberysubstance, provides toughness even at low temperatures. For the majority of applications, ABS can be used between −20 and 80 °C (−4 and 176 °F) as its mechanical properties vary with temperature.[3] The properties are created by rubber toughening, where fine particles of elastomer are distributed throughout the rigid matrix.
The advantage of ABS is that a variety of modifications can be made to improve impact resistance, toughness, and heat resistance. The last properties of the process will influence the final product. Molding at a high temperature improves the gloss and heat resistance of the product whereas molding at a low temperature is where the highest impact resistance and strength are obtained.
Polyethylene
Polyethylene is a thermoplastic polymer with variable crystalline structure and an extremely large range of applications depending on the specific type. It is one of the most versatile and most popular plastics in the world since the 1950s when it was developed by German and Italian scientists. The two most common types of this plastic are high-density polyethylene (HDPE) and low-density polyethylene (LDPE).
Its primary use is in packaging (plastic bags, plastic films, geomembranes, containers including bottles, etc.). Many kinds of polyethylene are known, with most having the chemical formula (C2H4)n. PE is usually a mixture of similar polymers of ethylene with various values of n. Polyethylene is a thermoplastic; however, it can become a thermoset plastic when modified (such as cross-linked polyethylene).
The advantages of polyethylene are high levels of ductility, tensile strength, impact resistance, resistance to moisture absorption, and recyclability. The higher the density of the polyethylene material used the stronger, more rigid, and more heat resistant the plastic is. The primary uses of polyethylene are plastic bags, plastic films, containers including bottles, and geomembranes.
Polycarbonate
Polycarbonate (PC) plastics are a naturally transparent amorphous thermoplastic. They are used to produce a variety of materials and are particularly useful when impact resistance and transparency are a requirement (ex: bullet-proof glass). Unlike most thermoplastics, PC can undergo large plastic deformations without cracking or breaks.
Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily worked, molded, and thermoformed. Because of these properties, polycarbonates find many applications. Polycarbonates do not have a unique resin identification code (RIC) and are identified as "Other", 7 on the RIC list.
Polyamide (Nylon)
Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made through step-growth polymerization or solid-phase synthesis yielding materials such as nylons, aramids, and sodium poly(aspartate). Synthetic polyamides are commonly used in textiles, automotive industry, carpets, kitchen utensils and sportswear due to their high durability and strength. The transportation manufacturing industry is the major consumer, accounting for 35% of polyamide (PA) consumption.[2
Nylon material is used in a large range of different applications because of its electrical properties, toughness, wear resistance and chemical resistance being quite impressive. Nylon has a high level of stability (helps with strength) and is resistant to many external factors like abrasion, impact, and chemicals. This material produces plastic parts used in many industries such as:
· Medical products
· Automotive products
· Sports equipment
· Apparel and footwear
· Industrial components
