Introduction
Thermoset vs thermoplastic are two broad categories plastic materials in injection molding, the primary difference are different behaviors once heated. Thermoset is strengthened in the presence of heat, but it cannot be remolded or heated after the initial forming process. While thermoplastic can be reheated and remolded without any chemical alternations. Therefore, this gives rise to different physical and chemical properties of thermoset vs thermoplastic. Thermoplastic materials have low melting points, otherwise, thermoset parts can withstand high temperature without structural integrity loss.
Now, engineers and designers must consider various characteristics, in order to select the most qualified thermoset or thermoplastic materials for particular applications. Nonetheless, in many products, we combine thermoset and thermoplastic together to take advantage of each material best features. All in all, familiar with unique properties of each material will assist decisions in product design and material selection.
Thermoplastic vs thermoset materials have different properties and applications. The main difference is thermoplastic has the ability to reverse solidification process and remelt into liquid, while thermoset doesn’t have this ability. Both thermoplastic and thermoset materials have excellent characteristics, for example lightweight, waterproof, noncorrosive, stress resistance, nontoxic, and manufacturability. These properties make thermoplastic vs thermoset materials popular in various industries. Such as: automotive, construction material, medical equipment and devices, telecommunication equipment, household appliances, sport equipment, toys, aerospace, product packaging.
What is Thermoset？
Thermoste (Thermoset plastics or thermosetting) is unique type of materials different from traditional thermoplastics, it encompasses a category of materials. We can set or cure thermoset materials into particular shapes by heat or chemical interaction. The curing or vulcanization create an irreversible chemical reaction with permanent cross-clinks. These cross-links provides the vulcanized polymer a three-dimensional structure, we cannot reheat and remold thermoset after initial heat forming.
After initial heat treatment, thermosets components will set in physical and chemical properties, therefore never impact by additional heat exposure. This process is similar to an egg boiling, once boiled hard, additional reheating will never cause dis-figuration.
Thermosets materials have resistance of heat, corrosion and mechanical creeping after initial heat forming. Therefore, this make thermosets the most suitable material for application with requirement of tight tolerances, excellent strength-to-weight characteristics, elevated temperatures resistance.
As traditional thermoplastics release viscous compounds in extreme environments, these materials are not suitable for many applications. While thermosetting materials provide chemical resistance properties with surface hardness and heat resistance, which exceeds thermoplastics. Common thermoset materials including:
Thermosetting Materials Types
Silicone
Silicone in this category of thermoset materials include High Consistency Rubber(HCR) and Liquid Silicone Rubber (LSR). In addition, silicone is odorless, colorless, chemical-resistant, oxidation-resistant, water-resistant, and thermal resistant. It is perfect for various products, like adhesives, seals, gaskets, lubricants, medical devices.
Polyester Resin
Polyester Resin (PR) is a stiff and hard material with excellent chemical resistance. While it is brittle, and requires lamination to strength. Its normal applications include electrical insulator, car and boat bodies, and materials adhesion.
Epoxy Resin
Epoxy resin (Epoxide) is hard and chemical resistant, it is a good electrical insulator. However, this material is brittle unless reinforce. Its common usage is adhesive fabrication for materials bonding, casting and encapsulation. Furthermore, It can also be used for surface coating and printed circuit boards.
Melamine Formaldehyde
Melamine Formaldehyde (MF) is a stiff, hard and strong material with some chemicals and stains resistance. It is common material for surface coating on tableware, electrical insulation and laminating work.
Urea Formaldehyde
Urea Formaldehyde (UF) is a stiff, hard and brittle. Commonly applied electrical insulators, electrical fittings, control and handles knobs, and adhesives.
Phenol Formaldehyde
Phenol Formaldehyde (PF) is also called Bakelite, it can be colored by artificial pigments. It is applied for dark-colored electrical fittings and products for domestic appliances, kettle handles and saucepan handles..
Liquid Silicone Rubber (LSR) has replaced thermoplastic and other silicone materials for application in automotive, communications, consumer products, food and beverage, medical devices. In reason of its superior durometer, elongation and tear strength.
Miwo LSR Materials
At Miwo, we provide a variety of liquid silicone rubber (LSR) materials for thermosetting plastics.
LSR as a common thermoset is a widely applied material in reason of its excellent properties, such as flexibility, heat resistance and chemical resistance. Our typical applications include touch surfaces, gaskets, heat insulation. In LSR molding process, Two uncured LSR mix into a liquid rubber solution with low viscosity, then this mixture cures in heat forming.
Our general LSR materials are displayed as following, we also provide special grades of fluorosilicone, medical and optical. You can find detail materials data sheet on LSR Materials Guide.
Miwo provides different types of thermoset materials in our LSR molding industry. The two thermoset molding processes are Reaction Injection Molding (RIM) and Resin Transfer Molding (RTM). Once apply LSR materials, we also need to find a whole set of unique design and material challenges. In order to fix these challenges, our engineering team recommend several items to consider in LSR designing process.
Thermoset Plastics Application
Thermoset plastics have enhanced performance of thermal stability, chemical resistance and structural integrity. Therefore, they are applied extensively in wide industries, such as automotive, electrical, appliance, lighting, energy.
The thermoset composites can meet various specifications of different production materials in low cost. It is suitable for high volume production with different sizes and consistent repeatability. Thermosets provide an alternative process for complex and geometric shapes in molding fabrication. Furthermore, it maintmaintainsain stability in all environments and temperatures.
Thermosets Advantages
Thermosets have many advantages, it will retain strength and shape with heat. This make it suitable for permanent large and solid parts production. In addition, thermoset components have excellent strength attributes, and never lose strength even exposed to higher operation temperatures.
Thermoset plastics are popular for worldwide manufacturers, they can replace other components with a lower cost. The benefits of thermoset are as following:
- High molded tolerance
- Various color and surface finishes (painting, polishing)
- High strength-to-weight ratio
- Low thermal conductivity
- Water, solvents and corrosion resistance
- Low tooling cost
- Structural integrity
- Electrical insulation
- Tailored elasticity
- Excellent adhesion
- Easy to add reinforcing fibers
Thermosets Disadvantages
There are some disadvantages of thermosets in molding process, we need to fix these related issues with additional solution.
- Low initial viscosity of thermosets will give rise to flash, this can be resolved by secondary operations.
- Low tensile and ductility requires thick walls in design. Designers should notice it from the beginning of LSR design.
- Compounds in thermosets are reactive system with useful shelf life. Production department should plan production schedules to avoid raw compounds waste.
- Different batch production may exhibit more variation and less consistency.
- Product quality depends on cross-linking degrees in molding process.
What is Thermoplastics？
Thermoplastic is the most common material around us, it is known for its versatility and recycle-ability. Normally, its polymers form structure once monomer units link into chains or branches. This material pellets will be molten and soften once heated, the fluid increase as heat temperature increase. Its curing process is total reversible as no chemical bonds in process. Therefore, thermoplastic can be remolded and recycled without negative effects on material physical properties. Different thermoplastic resins provide various performance benefits, most of them have properties of high strength, shrink-resistance, and easy flexibility. With different thermoplastic resins, thermoplastics can provide low-stress applications as plastic bags or high-stress application as mechanical components.
Thermoplastic Application
Thermoplastics have certain properties of recycle-ability, corrosive materials and environments resistance. Therefore, thermoplastic parts are applied in various industry, such as automotive, electrical, energy, consumer good. In addition, these products are considered to be ideal substitutes with minimum cost.
Thermoplastic Advantages
The primary advantage of thermoplastics is wide application in various industries. It is a high strength, shrink-resistance and easy bendable material with low relative process cost. Furthermore, thermoplastic components are easy to produce with high volume and tight tolerance. The benefits of thermoplastic are following:
- Highly recyclable,
- Superior aesthetic finishes,
- High impact resistance,
- Remolding and reshaping capability,
- Chemical resistance,
- Hard crystalline or rubbery surface options,
- Eco-friendly manufacturing.
Thermoplastic Disadvantages
The primary disadvantage of thermoplastics is low melting point. Some thermoplastic types will melt once exposed to sunlight for an extended period. Furthermore, it has poor resistance to organic solvents, hydrocarbons, and highly polar solvents. Normal disadvantage of thermoplastics are following:
- Harder to add reinforcing fibers,
- Difficult to prototype,
- Soften or molten once heated,
- More expensive than thermset materials.
Conclusion
Although thermosets and thermoplastics have wide range of materials, professional manufactures require intended operating technology to avoid any product failure. Miwo as the most advanced LSR (thermoset) molding manufacturer in China, has produced billions of thermset component for global customers.
