A thermoplastic material is any plastic polymer that can be heated and reset into a particular designated shape upon cooling. Most thermoplastic materials have a high molecular weight and will melt into a molten state quickly. Because of this, thermoplastics can be remolded and recycled without negatively affecting the material’s physical properties.
It is these general qualities that make thermoplastic polymers ideal for injection molding. However, each particular thermoplastic exhibits different qualities, advantages, and disadvantages, making it critical to select the right material for the application at hand. Additional fillers and additives can be also used to provide specific characteristics that better meet the application requirements.
Thermoset vs. Thermoplastic Material
It should be noted that thermoplastic materials are very different from thermoset materials. Though similar, thermosets can only be heated and molded once—they cannot be changed or melted back into their original shape.
Polymers are linked together during the curing process of thermosetting plastic, and they form a permanent chemical bond. This permanence makes thermosetting materials more ideal for heavy-duty applications like electronics or appliances. In contrast, thermoplastics are most often used for consumer goods, machine parts, medical equipment, and packaging and storage materials.
- Recyclable & reusable
- Environmentally friendly
- More options for sheen, variance, etc.
- Chemically retardant options
- High impact resistance
- More cost effective
- Dimensional stability
- Very malleable design
- Excellent aesthetic appearance
Modern technology has recently given rise to thermoplastic elastomers, a.k.a. TPEs or thermoplastic rubbers. Basically, before this technology, all rubber materials were thermosets, and once injected and molded, could not change.
Now, TPEs have blended the two materials (rubber and plastic) to provide the best of both worlds. These new materials have proven very useful in the automobile industry, aerospace industry, and many consumer markets.
TPEs are known as two-phase systems because they are created by a hard thermoplastic phase is combined mechanically or chemically with a soft elastomer phase. Certain characteristics of TPEs are obtained from each phase.
From the hard phase, the TPEs get properties like processing and continuous temperatures, tear strength, and chemical and fluid resistance. From the soft phase, they get their hardness, flexibility, and compression set, among other properties.
Common Thermoplastic Materials
Stack Plastics works with a wide range of thermoplastic materials in our injection molding processes. From standard to exotic to engineered, we have experience molding many materials for different applications. We can also blend thermoplastic materials with additives like PTFE for enhanced strength and durability.
The following thermoplastic materials can be used as an alternative to PVC or for any of your unique applications needs.
Acrylic is a thermoplastic polymer that exhibits many glass-like optical qualities but is much more hardy and protective. It is often known as Lucite, Perspex, and Plexiglas. Acrylics are used in nearly every industry, and are used as a glass substitute for items such as:
- Motorcycle helmet visors
- Aircraft windows
- Viewing ports of submersibles
- Lenses of exterior lights of automobiles
Because of its impact resistance and strength, acrylic is also used to make googles and lenses.
ABS, or acrylonitrile butadiene styrene, is a synthesized plastic that combines styrene and acrylonitrile. This safe thermoplastic is used in many consumer products that humans come in direct contact with, such as cell phones, toys, microwaves, and other appliances. ABS thermoplastic is known for being strong, light, versatile, and tough.
ABS consists of three distinct monomers, and by combining them, the thermoplastic becomes flexible and lightweight. Because of this, ABS flows smoothly and is perfect for injection molding.
Polybenzimidazole (PBI) is an artificial thermoplastic polymer with one of the highest melting points of any material that is applicable for use as a fiber. It is the most high-performance engineered thermoplastic material available. Because of this, this thermoplastic is used as a base for high demand equipment that is used by militaries throughout the world, as well as firefighting and police forces.
Because of its extreme hardness and durability, PBI can be difficult to machine, but Stack Plastics is experienced in engineering for demanding industries.
Polyethylene is not one specific material, but actually a group of materials characterized by the type, structure, and thickness of the polymer. Some common types include High-Density polyethylene (HDPE) that is used to make milk jugs and water pipes, and the softer, more flexible Low-Density polyethylene (LDPE) that is used to make squeeze bottles and bags.
In general, the higher the density, the higher the tensile and flexural strength, chemical and abrasion resistance, and surface hardness.
Because these thermoplastic polymers are highly resistant to temperature changes, they are often used in high stress environments, such as piping, oil transportation, and in the retail industry.
A homopolymer is one that is produced by the polymerization of a single monomer. They are known for being a tough and resistant thermoplastic material. They commonly used in the end consumer market for smaller goods, such as kitchenware.
There are several kinds of homopolymer thermoplastics including polypropylene, polycarbonate, and polyester. In general, all of these thermoplastics are great for injection molding.
A copolymer is a plastic material produced by the copolymerization of two or more different monomers. They commonly are a glossy, cost effective material. Copolymer thermoplastic material is used in a variety of applications, including industrial back end applications and smaller consumer items such as kitchenware.
Polyesters are extremely hardy materials that are fit for a large range of temperature and environmental demands. Polyester thermoplastics are among the most widely used injection molding polymers, seen most commonly in water bottles, but also have wide applications in the industrial sphere. They are known for their strength, stiffness, and toughness, as well as chemical resistance.
Polyurethane is a clear and flexible thermoplastic polymer that is most often used to produce shoe soles, gaskets, and wheels. It is extremely versatile and can be formulated to provide wide ranging characteristics. It exhibits excellent wear and abrasion resistance, and remains highly elastic and impact resistant, even at the hardest durometers or in extremely low temperatures. They are also resistant to oil and grease.
Styrene acrylonitrile is a copolymer and one of the toughest polymers in common use. It is known for its excellent toughness, rigidity, and dimensional stability. It is highly resistant to breaking and is often seen in kitchen applications. It is also used for applications such as:
- Computer components
- Packaging materials
- Autoclavable medical devices
- Battery cases
Contact Stack Plastics for Custom Plastic Injection Molding
Stack Plastics is a custom plastic injection molding company that specializes in engineering thermoplastics, as well as other materials such as elastomers and exotic resins. We manufacture molding for a variety of industries and applications, including medical devices and consumer products.
This list of thermoplastic materials is by no means exhaustive. Please contact Stack Plastics to discuss your unique material requirements.aterial requirements.