Thermoplastic and Thermosetting plastic are two separate forms of polymer powders, which are differentiated based on their behavior when reacting to the application of heat. The primary difference between the two is that a thermoset is a material that becomes strong when heated, but cannot be regenerated or heated after initial formation, while thermoplastics are not necessarily without any chemical changes. Can be heated, removed, and cooled.
As a result of these physical and chemical properties, thermoplastic materials have low melting points while Thermoset products can withstand higher temperatures without loss of their structural integrity.
In this article, the uses and applications of each of these types of Thermosetting polymers will be presented, including a summary of the relative advantages and limitations of each.
- What are Thermosetting Plastics?
- What are Thermoplastics?
- Thermoplastic & Thermosetting plastic – A Summary
What are Thermosetting Plastics?
Plastic is one of the most common materials used to make stuff today, the keyboard you’re typing on the International Space Station plastic is here to stay. So how can plastic that can make something as simple as a pen make something so complex that it can withstand hard physical and chemical elements such as excess heat and corrosion?
The answer is thermosetting plastics or thermoset. Thermosetting is unique and quite different from traditional plastic materials such as thermoplastic, so what is the difference between thermoplastic and thermosetting? Unlike traditional thermoplastic parts, which melt and dissolve when exposed to more heat, the thermoset components contained in their names are set to their physical and chemical properties after initial heat treatment and are therefore no longer affected by greater heat exposure.
The process is very similar to hard boiling an egg. Once the egg is boiled, additional reheating does not cause disfiguration similar to the curing process associated with a thermoset part. After the initial heat build-up, the thermostat materials have the ability to exhibit resistance to heat, corrosion, and mechanical creep, making them perfectly suitable for use in components for which they are exposed to high temperatures, as well as Tight tolerance and excellent power-to-load characteristics are required.
Application of Thermosetting Plastics
- Thermoset plastics offer an enhanced high-performance combination of thermal stability, chemical resistance, and structural integrity.
- Thermoset ingredients are used broadly in a wide range of industries and are used in the automotive, appliance, electrical, light, and energy markets due to their excellent chemical, thermal stability with excellent strength, hardness, and moldability.
- Thermosetting plastic composites are capable of meeting the specifications of a wide range of production materials at a very low cost. Their use allows for the assortment of small and large parts to be fabricated with high production volumes while maintaining their repetition continuously from batch to batch.
- Thermosets give an alternative method when complex and geometric patterns cannot be obtained through metal fabrication or the use of thermoplastics but can be manufactured in a mold. Thermoset plastics sustain their stability in all weather and heat.
Advantages of Thermosetting Plastics
The usage of thermoset plastics has a number of advantages. Unlike thermoplastics, they maintain their durability and shape even when heated. This provides thermosetting plastics well-suited to the making of permanent parts and large solid shapes. Additionally, these elements have excellent durability attributes (although they are brittle), and will not lose important strength when opened to higher operating temperatures.
Thermosets plastics have increased its demands between manufacturers, who have switched to their use as a lower-cost replacement for metal components.
The advantages that thermoset plastics can offer over their metal counterparts include:
- Available molded-in tolerances
- Choice of color and surface finishes
- High strength-to-weight ratio and performance
- Outstanding dielectric strength
- Low thermal conductivity and microwave transparency
- Resistance to corrosion effects and water
- Lower tooling/set-up costs
- Reduced production costs over fabrication using metals
- More Resistant against high temperature
- Hard and rigid
- Excellent aesthetics finishes
- High mechanical property
- Excellent dimensional stability
Disadvantages of Thermosetting Plastic
There are several disadvantages to the usage of thermosets whereas the material properties are not as developed as those of thermoplastics.
The low initial viscosity of materials results in a flash and the need for secondary operations. Also, low tensile strength and ductility tend to result in parts that require designs with thick walls.
The compounds used in thermosets are reactive methods, which can affect the useful shelf life. Batch methods may exhibit greater variation and less consistency from lot to lot.
High levels of some filler in the materials may appear in excessive tool wear. The product quality is dependent upon the degree of crosslinking set while the molding cycle.
- Cannot be recycled.
- Cannot be remolded or reshaped.
- Poor thermal conductivity for housing replacements.
- Much more difficult to surface finish.
- The rigidity of the material can result in product failure when used in high in vibration applications.
Type of Thermosetting Plastic & Thermosetting Plastic Materials List
Thermosetting polymers are made from various kinds of material that serve key roles and importance in the plastics fabrication industry. The two thermoset molding compound methods are Reaction Injection Molding (RIM) and Resin Transfer Molding (RTM).
Composite thermoset materials consist of a matrix and a dispersed, fibrous, or continuous second phase. Casting resins include a catalyst or hardener. Thermoset electrical resins and electronic-grade products are utilized in potting or conductive adhesives, encapsulating mixtures, and dielectric sealants.
Thermal compounds are built to form a thermally conductive layer on a substrate, either inside components or within a complete electronic product. Thermoset purging mixtures are used to clean molding machines between runs of various colors or compositions. Gap filling products are utilized to fill in gaps or spaces between two surfaces to be bonded or sealed.
Specific types of thermoset materials that are in use within the plastics fabrication industry include the following:
RIM Thermosetting Plastics:
- pDCPD (polydicyclopentadiene)
- Structural Foams
RTM Thermosetting Plastics (Fiberglass-reinforced):
- Vinyl Ester
Other Types of Thermosets and Thermoset Resins:
- Epoxy (e.g., carbon fiber epoxy resin)
- Bismaleimide (BMI)
- Polytetrafluoroethylene (PTFE)
- Polyvinylidene fluoride (PVDF)
- Urea Formaldehyde
What are Thermoplastics?
As discussed above, plastics are universally recognized as real-world applicability of the use of chemistry. From plastic containers, bottles, and life-saving medical devices to aerospace components, plastic is a material used in applications around us.
The thermoplastic polymer is a type of plastic that is known for its versatility and recycling. When forming thermoplastic polymers, repeating units called monomers link together into chains or branches.
On heating, the thermoplastic pellets soften and become more liquid as more heat is administered. The curing process is 100% reversible because there is no chemical bonding. This characteristic permit thermoplastic to be remolded and reused without negatively harming the material’s physical properties.
There are a variety of thermoplastic resins that offer various performance benefits, but the majority of materials commonly used offer high strength, shrink-resistance, and easy flexibility. Base on the resin, thermoplastics can assist low-stress applications such as plastic bags or can be practiced in high-stress mechanical parts. Examples of thermoplastic polymers include PVC, polyethylene, and nylon.
Applications of Thermoplastics
Polluted, acidic, such as environments can be found in modern cities, steel piping systems are often vulnerable to corrosion or rust and therefore require special provisions for corrosion protection. The costs associated with protecting steel piping systems that are exposed to these harsh environments can be expensive. Thermoplastic is considered a favorable option to reduce these costs. Some properties of thermoplastic that make them a suitable substitute material:
- Their ability to withstand corrosive materials and corrosive environments.
- Remaining to bring materials of intense temperatures.
- Their capacity to handle virtually any type of fluid transport application.
- ABS: LEGO bricks, safety hats, whitewater canoes, musical instruments
- Acrylic: Lucite, Perspex, Plexiglass
- Polyester: Clothing, conveyor belts, blankets, mousepads, furniture, Yarn, rope,
- Polypropylene: Carpets, textiles, packing, Lab equipment, labeling
- Polystyrene: Disposable cutlery, smoke alarm housings, foam cups, models, CD/DVD cases
- Cellulose Acetate: Cigarette filters, playing cards, eyeglass frames, adhesives, photography
- Nylon: Carpet, rope, strings for musical instruments, fishing line, fabric
Other common applications for thermoplastic include high-pressure polyethylene for encapsulating rigid objects such as electrical equipment. Low-pressure polyethylene is very elastic and ideal for insulating electrical cables. Polyamide is most commonly associated with the production of ropes and belts.
Advantages and Disadvantages of Thermoplastics
Advantages of Thermoplastics
The primary advantage of thermoplastics is a wide range of applications. Thermoplastics are lightweight materials, high strength, and have relatively low processing costs. Additionally, thermoplastic components are relatively easy to manufacture with high volume and precision.
- Extremely adhesive to metal
- High recyclable
- Superb impact resistance
- Can be remolded and reshaped
- Excellent corrosion resistance
- Slip enhancement
- Detergent and chemical resistance
- Flexibility and elongation of the coating film
- Electrical insulation
- Chip resistance
- Aesthetically-superior finishes
- Superb corrosion resistance
Disadvantages of Thermoplastics
The primary limitation of using thermoplastics instead of materials such as metal is their comparatively low melting point. Certain types of low-quality thermoplastics can melt when they’re exposed to the sun for long periods. Furthermore, thermoplastics can have lower resistance to organic solvents, hydrocarbons, and highly polar solvents.
Thermoplastics are susceptible to creep, which occurs when the material stretches and weakens under exposure to long-term stress loads. The susceptibility to creep is further exacerbated by the lower melting temperature of the material. Different types of thermoplastics, such as composites, can crack instead of becoming deformed under high-stress conditions.
- Thermoplastics degrade more easily in direct sunlight or under UV exposure
- Not all thermoplastics resist hydrocarbons, organic solvents, and polar solvents
- Some types of experience creep under long-term loading
- Can fracture rather than deform under high stress
Types of Thermoplastic Materials
Types of thermoplastics usually employed for manufacturing include polyethylene, polyvinyl chloride, and polystyrene, which often is used for packaging. Other groups of thermoplastics are fluoropolymers, acrylics, polyesters, polyimides, and nylons.
All of these types can be melted down repeatedly and re-shaped into different forms. For example, a foam cup is a thermoplastic material that can be remelted and fabricated into a dish.
Some of the most common thermoplastic materials in use include:
- Acetal Copolymer Polyoxymethylene
- Acetal Homopolymer Polyoxymethylene
- Polyvinyl chloride (PVC)
Thermoplastic & Thermosetting plastic – A Summary
Thermoplastic and thermosetting plastics come in a wide range of material options and can serve a variety of applications as long as the material limitations cannot cause product failure under the intended operating conditions. The basic characteristics of these materials are the same: high versatility and recycling. When it comes to useful applications in the real world, you have to work hard to find better examples than the production of plastics through these two processes.