Thermoplastics and thermosets are two major categories of polymer materials that differ primarily in their response to heat. Thermoplastics can soften and reshape when heated, making them recyclable, easy to process, and suitable for mass production. Thermosets, on the other hand, form an irreversible molecular structure after being heated and cured. They have extremely high heat resistance, chemical stability, and mechanical strength, but they cannot be reshaped. I will take you through their chemical properties, mechanical properties, application areas, and processing methods to help you choose the most suitable material.
何 Are Thermoplastics
Thermoplastics are a class of polymer materials that soften and shape when heated, and return to a solid state when cooled. Their molecular structure exists in a linear or branched form, and they do not form a permanent cross-linked structure, so they can be melted and reshaped many times. This property makes them ideal materials for mass production, rapid prototyping and recyclability.
The main advantage of thermoplastics is their processing flexibility. Due to their low melting point range (usually between 100°C and 250°C), they can be formed by processes such as injection molding, extrusion, and blow molding, making them suitable for a variety of industrial and consumer applications. In addition, thermoplastics are generally low in density (e.g., the density of polypropylene PP is only 0.91 g/cm³), which makes them advantageous in lightweight design, such as lightweight parts in the automotive industry.
In my actual processing experience, the recyclable characteristics of thermoplastics play an important role in environmentally friendly manufacturing. For example, in a food packaging project, I chose polyethylene (PE) as the main material because it not only meets food safety standards, but also can be recycled and reused through melt melting, reducing waste disposal costs.
Common Thermoplastics Types:
- Polyethylene (PE) : Widely used in food packaging, plastic bags, pipes, etc., with excellent flexibility and chemical resistance.
- Polypropylene (PP) : Used in automotive parts, medical devices, home appliance casings, etc., with good heat resistance (melting point 160-170°C) and impact resistance.
- Polycarbonate (PC) : Mainly used in optical lenses, safety helmets, and electronic equipment casings. Its high transparency and impact resistance make it widely used in high-end products.
- ABS : Used for Lego building blocks and household appliance casings, it has good mechanical strength, impact resistance and easy processing, and its melting point is about 200°C.
何 Are Thermoset Plastics
Thermosetting plastics are a class of polymer materials that form a stable three-dimensional molecular network structure after being cured by heat. Once cured, their molecular chains form an irreversible structure through cross-linking reactions, so they will not re-melt or reshape when heated like thermoplastics. Because of this, thermosetting plastics generally exhibit extremely high heat resistance, chemical stability and mechanical strength.
Thermosets typically cure at temperatures between 150°C and 250°C and release heat during the curing process. Due to their strength and high temperature resistance, they are often used in environments that need to withstand high temperatures, pressures or chemical corrosion for a long time. For example, in aerospace and automotive manufacturing, I often use epoxy composites because they provide excellent heat resistance (up to 300°C and above) and mechanical properties.
However, the non-recyclability of thermoset plastics limits their environmental sustainability. During the manufacturing process, waste cannot be re-melted and recycled, and can only be ground for reuse or landfilled. In an electronic packaging project, I chose phenolic resin as the main material for the circuit board because it can maintain insulation in high temperature environments of 200°C, but its waste disposal options must also be considered.
共通 Types Of Thermoset Plastics:
- Epoxy Resin : Mainly used in electronic packaging, composite material manufacturing, and industrial adhesives. It has extremely high strength and chemical resistance after curing.
- Phenolic Resin : widely used in electrical insulation materials and high temperature resistant parts. After curing, the heat resistance can reach over 250°C.
- Polyurethane (PU) : Used for wear-resistant coatings, automotive parts, and elastomeric structures, with excellent weather resistance and mechanical properties.
What Is The Difference Between Thermoplastics And Thermosetting Plastics
The main differences between thermoplastics and thermosetting plastics are reflected in chemical structure, mechanical properties and processing methods. The characteristics of thermoplastics are that they can be melted and reshaped repeatedly, making them suitable for mass production and recycling. Thermosetting plastics form a stable molecular network structure after curing and cannot be re-melted, but their high temperature resistance, chemical corrosion resistance and high mechanical strength make them more suitable for high-demand industrial applications.
Chemical Structure
The molecular structure of thermoplastics consists of linear or branched polymers without permanent chemical crosslinks between molecules. This means that they soften when heated and resolidify after cooling, so they can be melted and molded multiple times. For example, polyethylene (PE) and polypropylene (PP) are typical thermoplastics, and their chemical structure makes them suitable for processing processes such as injection molding, extrusion and blow molding.
In contrast, thermosetting plastics undergo irreversible chemical cross-linking during the curing process to form a three-dimensional molecular network. This structure prevents them from melting when heated, but instead keeps them in a solid state, and they remain stable even at extreme temperatures. For example, epoxy and phenolic resins form a strong network structure after curing, and they will not deform or melt even at high temperatures above 200°C. This property makes thermosetting plastics ideal for applications in high temperature environments and with high mechanical strength requirements.
Mechanical Properties
In terms of mechanical properties, thermosetting plastics are generally harder, more resistant to high temperatures, and more resistant to chemical corrosion than thermoplastics. For example, silicone is a typical thermosetting material that can remain stable at a high temperature of 250°C, while most thermoplastics begin to soften or even decompose at this temperature.
On the other hand, thermoplastics are generally more flexible and impact-resistant than thermosets. For example, ABS (acrylonitrile butadiene styrene) is a thermoplastic material with excellent toughness and impact resistance, which is why Lego bricks, home appliance housings, etc. all use ABS. Polycarbonate (PC) is also a thermoplastic. It not only has high transparency but also can withstand large mechanical impacts. Therefore, it is widely used in applications such as protective masks and car windshields.
However, due to their chemically cross-linked structure, thermosets may exhibit better creep resistance when subjected to high loads. For example, in the electronic packaging and aerospace fields, I have used epoxies to manufacture high-precision parts with much greater rigidity and dimensional stability than thermoplastics.
Production And P処理
One of the main advantages of thermoplastics is their ease of processing. They can be mass-produced through a variety of processes including injection molding, extrusion, blow molding and 3D printing. For example, in a medical device production project, I chose polypropylene (PP) as the main material and manufactured a batch of high-precision catheters through the injection molding process. Due to the low melting point of PP (160-170°C), the production efficiency was significantly improved.
In contrast, thermoset plastics are processed primarily by molding, laminating, and casting. Once solidified, they cannot be remelted, so the process requires highly precise molds and temperature control. In an electronic packaging project, I used phenolic resin to manufacture circuit boards. This material provides excellent heat resistance and electrical insulation properties after high-temperature curing, but its processing process is more complicated than thermoplastics and does not allow subsequent shape adjustment.
In addition, thermoplastics can be used for rapid prototyping through 3D printing, while thermosets are relatively less used in this field and usually require special light-curing resins (SLA or DLP printing technology) to achieve precise molding.
メリット And Disadvantages Of Thermoplastics And Thermosets
Both thermoplastics and thermosets have their own limitations. Thermoplastics have low heat resistance and are easily deformed or degraded in high temperature environments, while thermosets are stable but non-recyclable and have high processing costs. Therefore, during the manufacturing process, we need to comprehensively consider the strength, durability, plasticity and environmental impact of the material to select the solution that best meets the product requirements.
Here is an analysis of the main advantages and disadvantages of these two types of plastics that I have sorted out for you :
メリット Of Thermoplastics
Thermoplastics are widely used in the manufacturing industry due to their recyclability, easy processing and low production costs, especially for products produced in large quantities.
Recyclable
Thermoplastics can be remelted and reshaped after heating, so their waste can be recycled and reused, reducing material waste. In the plastics industry, more than 70% of thermoplastics are used in recyclable products such as PET plastic bottles and HDPE pipes. This environmentally friendly feature makes it an important material in the circular economy.
Easy-To-Pプロセス
Thermoplastics can be quickly molded through injection molding, extrusion, 3D printing, etc., making the production process more flexible. For example, injection molding can complete the manufacture of a product within 30-60 seconds , making it an ideal choice for large-scale production.
Lightweight
The density of most thermoplastics is between 0.9-1.5 g/cm³ , which is much lower than that of metal materials. Therefore, in the automotive industry, many parts use thermoplastics to replace metals to reduce weight and improve fuel efficiency. For example, polycarbonate (PC) is used to make bulletproof glass and car headlight covers, and its impact resistance is 250 times that of ordinary glass .
低い Production Cost
Since thermoplastics can be processed through efficient injection molding or extrusion processes, their unit production cost is much lower than that of thermosetting plastics. For example, the processing cost of ABS and PP is 20-50% lower than that of thermosetting plastics , making them widely used in consumer electronics, medical equipment and packaging industries.
デメリット Of Thermoplastics
Although thermoplastics have many advantages, they have certain limitations in terms of heat resistance, mechanical strength and chemical stability.
Deformable
Thermoplastics tend to soften or deform in high temperature environments. For example, the melting point of PP is 130-171°C , while ABS begins to soften at 85-105°C . Therefore, thermosetting plastics have more advantages in high-temperature application scenarios (such as engine compartments or high-temperature electronic equipment).
低い Strength
Compared with thermosetting plastics, thermoplastics have lower mechanical strength and are prone to cracking or fatigue after long-term use. For example, ordinary PVC will gradually become brittle under ultraviolet light, shortening its service life by 30-50% .
Poor Chemical Resistance
Some thermoplastics (such as polystyrene PS, ABS) have poor tolerance to solvents and acids and alkalis and are susceptible to chemical corrosion. In a laboratory environment, I have tested ABS in certain industrial solvents (such as acetone) and found that it began to crack after only 10 minutes , while thermosetting epoxy resins remained stable.
メリット Of Thermoset Plastics
Thermoset plastics perform well in high temperature, high pressure and corrosive environments and are suitable for harsh industrial applications and high-strength structural parts.
高い T温度 Sタビリティ
Due to the cross-linking bonds in the molecular structure, thermosetting plastics do not melt at high temperatures. For example, epoxy resins have a heat resistance of up to 200-300°C , and polyimide (PI) can even remain stable at 400°C , so they are often used in aerospace, electronic packaging and other fields.
Thermosetting
plastics provides excellent rigidity and dimensional stability. For example, in automobile manufacturing, phenolic resin is used in brake pad manufacturing, and its compressive strength can reach 200 MPa , which is much higher than ordinary plastics. In addition, in composite materials, the stiffness of glass fiber reinforced epoxy resin can reach 80-150 GPa , which is close to some metal materials.
High-Strength Applications
Thermosetting plastics are widely used in highly corrosive and high-load environments. For example, polyurethane (PU) coatings on offshore oil platforms can withstand acidic and alkaline environments with a pH value of 2-12 and have a service life of more than 15 years , which is much better than thermoplastics .
デメリット Of Thermoset Plastics
Despite their superior properties, thermoset plastics have limitations in how they can be processed and recycled.
Thermosetting
Plastics makes it impossible to remelt after solidification, so it cannot be recycled. During the production process, I found that the waste of thermosetting plastics can usually only be degraded by mechanical crushing or chemical treatment, which limits its environmental performance.
Higher Costs
The production process of thermosets is longer than that of thermoplastics. For example, epoxy composites usually require 4-6 hours of curing time, while injection molding of thermoplastics can usually be completed within 30-60 seconds . Therefore, the manufacturing cost of thermosets is generally 20-100% higher than that of thermoplastics .
Fragile
Although thermosets have high rigidity, they have poor toughness and are prone to breakage under impact. For example, in an electronic housing test, I found that the housing made of thermosets had a 30% breakage rate in a 5-meter drop test , while the housing made of PC material only had 5% breakage. Therefore, in applications that require high impact resistance, thermoplastics have more advantages.
The Influence Of Thermoplastics And Thermosetting Plastics In P処理
Since thermoplastics can be softened by heating and return to a solid state after cooling, they are suitable for efficient production methods such as CNC processing, injection molding and 3D printing. However, thermosetting plastics form an irreversible molecular cross-linked structure after curing and cannot be reshaped, which requires molding, lamination or light curing during processing. The difference in these processing methods directly affects production efficiency, manufacturing costs and the mechanical properties of the final product .
Below, I will analyze in detail the applicability of these two types of materials in different processing methods.
CNC Machining
CNC machining is a high-precision cutting process suitable for the precision manufacturing of various plastic parts. Thermoplastics and thermosets behave differently in CNC machining and require different processing strategies.
Thermoplastics
The low melting point of thermoplastics makes them easily deformed due to frictional heat during high-speed cutting. For example, when machining polycarbonate (PC), if the cutting speed exceeds 10,000 RPM, the chips are easy to melt and adhere to the tool, affecting the machining accuracy. Therefore, I usually use low speed and high feed (6,000-8,000 RPM) and use coolant to reduce heat accumulation and ensure surface finish.
Thermosetting Plastics
Due to the high rigidity and brittleness of thermosetting plastics, edge cracking or delamination is prone to occur during CNC machining. For example, when machining phenolic resin (Phenolic), if the feed rate exceeds 500 mm/min, cracks are likely to appear on the workpiece surface. I usually use diamond-coated tools, reduce the cutting feed rate to 200-400 mm/min, and use a small cutting depth and multiple machining methods to reduce the internal stress of the material and improve the processing stability.
Injection Molding
Injection molding is an efficient way to process plastics and is suitable for large-scale production. Thermoplastics and thermosets behave significantly differently in injection molding.
Thermoplastics
Since thermoplastics can be melted and reshaped, the injection molding process is very flexible and usually completes a molding cycle within 30-60 seconds. For example, polypropylene (PP) is widely used in the production of car bumpers and home appliance housings. In an electronic device casing manufacturing project, I used a two-component injection molding process to combine TPU (thermoplastic polyurethane) and ABS to produce a high-strength, impact-resistant mobile phone case, which greatly improved the durability of the product.
Thermosetting Plastics
Injection molding of thermosetting plastics is different from thermoplastics. After molding, they undergo chemical cross-linking and cannot be reshaped once cured. For example, when manufacturing epoxy resin electronic packaging, I need to use a mold temperature of 180-200°C and control the curing time to 3-5 minutes to ensure that the material is fully cross-linked and improve the electrical insulation performance of the product. This processing method makes thermosetting plastics more suitable for high-temperature and high-strength application scenarios, but the production cycle is relatively long.
3D Printing
3D printing technology is increasingly used in the manufacturing industry, and thermoplastics and thermosets have different performances in this field.
Thermoplastics
Thermoplastics are mainly used in fused deposition modeling (FDM) and stereolithography (SLA) in 3D printing. For example, PLA (polylactic acid) is a common material for FDM printing, suitable for low-cost prototyping, while PA (nylon) is printed by SLS (selective laser sintering) technology and can be used for high-strength parts such as gears and engineering parts. In an automotive parts development, I used PA12 nylon powder SLS printing to manufacture a high-strength fan blade, whose impact strength is 30% higher than that of traditional ABS materials.
Thermosetting Plastics
Thermosetting plastics are mainly used for photocuring 3D printing (DLP, SLA), and common materials include epoxy resin, polyurethane resin, etc. These materials can be cured under 385-405nm ultraviolet light to form high-precision parts. I once used SLA photocuring 3D printing to make biocompatible dental models in medical device production. The surface roughness was as low as Ra 0.02µm, which was 10 times smoother than traditional FDM printing, greatly improving the accuracy of dental surgery simulation.
What Are T彼 Applications Of Thermoplastics And Thermosetting Plastics
Thermoplastics are widely used in industries such as consumer goods, automobiles and medical devices due to their recyclability, easy processing and good toughness. Thermosetting plastics have important applications in aerospace, electronics and high-end industrial equipment manufacturing due to their high heat resistance, stable mechanical properties and excellent chemical resistance.
The following is a comparison of their typical applications in different fields :
| Application Areas | Thermoplastics | Thermosetting Plastics |
| 自動車産業 | 1. Polypropylene: used for bumpers, impact resistance, good low temperature toughness. 2. Polycarbonate: used for headlight housing, high transparency, strong weather resistance. 3. ABS: used for instrument panels, door panels, providing structural strength and appearance texture. | 1. Epoxy resin: used in car body composite materials to improve strength and corrosion resistance. 2. Phenolic resin: used in engine parts, high temperature resistance, low smoke and low toxicity. |
| コンシューマー・エレクトロニクス | 1. Polycarbonate: used for smartphone housings, impact and wear resistance. 2. ABS: used for electronic device housings, good weather resistance and excellent processing performance. 3. Polyoxymethylene: used for keyboard keys, low friction and strong durability. | 1. Polyimide: used for flexible circuit boards, with excellent high temperature resistance and stability. 2. Epoxy resin: used for printed circuit boards, improving heat resistance and insulation. |
| 医療機器 | 1. Polypropylene: used for disposable syringes, strong chemical resistance. 2. Polyetheretherketone: used for human implants, high biocompatibility. 3. Polyethylene: used for infusion bags and catheters, soft and safe. | 1. Phenolic resin: used for surgical instrument handles, high temperature resistance, easy to sterilize. 2. Epoxy resin: used for dental fillings, high strength and good stability. |
| Packaging Industry | 1. Polyethylene terephthalate: used for food-grade plastic bottles, high transparency and food safety. 2. High-density polyethylene: used for milk bottles, good impact resistance. 3. Low-density polyethylene: used for plastic bags, strong flexibility. | 1. Polyurethane: used for industrial packaging coatings, abrasion resistance and impact resistance. 2. Epoxy resin: used for protective coatings, enhancing chemical resistance. |
| 航空宇宙 | 1. Polyetheretherketone: used for lightweight structural parts, high temperature resistance and impact resistance. | 1. Carbon fiber reinforced epoxy resin: used for fuselage composite materials, reducing weight by 30% and increasing strength by 40%. 2. Phenolic resin: used for high temperature resistant coatings, with a heat resistance of over 300°C. |
| Electrical Insulation | 1. Polycarbonate: used for electrical switch housing, flame retardant and impact resistant. | 1. Phenolic resin: used for high voltage switches, with excellent electrical insulation performance. 2. Polyimide: used for aerospace electronic components, with a temperature range of -269°C to 400°C. |
| Industrial Equipment | 1. Nylon: used for mechanical gears, with good wear resistance and lubricity. | 1. Polyurethane: used for chemical pipeline coating, corrosion resistance and wear resistance. 2. Phenolic resin: used for acid and alkali resistant equipment to improve chemical protection performance. |
よくある質問
何 Is The Difference Between Thermoplastics And Thermosets?
In my manufacturing practice, I found that the core difference between thermoplastics and thermosetting plastics is their response to heat. Thermoplastics can be softened and reshaped by heating, and return to a solid state after cooling, so they are suitable for processing methods such as injection molding, extrusion and 3D printing. In contrast, thermosetting plastics form a stable molecular cross-linked structure after curing and cannot be heated and molded again, but they are resistant to high temperatures and chemicals.
何 Are T彼 Disadvantages Of Thermoset Pラスティクス？
The main problem I face when working with thermosets is that they cannot be recycled and reshaped, which means that the waste disposal costs are high. In addition, thermosets are more brittle and break more easily than thermoplastics. For example, I have used phenolic resin in the production of electrical equipment housings. Although it has excellent electrical insulation properties, it has low impact resistance and tends to crack under stress. In addition, the processing technology of thermosets is complicated and requires high temperature curing, which leads to longer production cycles and higher manufacturing costs.
Is PVC A Thermoplastic Or A Thermoset?
In my experience, PVC (polyvinyl chloride) is a common thermoplastic that I often use in pipes, building materials, cable sheathing, etc. PVC can be softened by heating and remains solid after cooling, which is suitable for multiple processing. PVC has a melting point between 100-260°C and has good chemical resistance, which makes it suitable for waterproof materials and corrosion-resistant applications. To improve flexibility, plasticizers are added to make it more widely used, such as medical-grade hoses or wire insulation.
Is Teflon A Thermoset Plastic?
Although Teflon (PTFE) is a thermoplastic, I have found in actual use that its high temperature resistance and chemical stability are almost equivalent to thermosetting plastics. Teflon has a melting point of about 327°C and can remain physically stable in high temperature environments without melting or flowing. Therefore, it is widely used in anti-stick coatings, seals, and high-temperature electrical insulation materials.
Is LDPE A Thermoplastic Or A Thermoset?
LDPE (Low-density polyethylene) is a thermoplastic that I often use when producing plastic bags and food packaging films. LDPE has a melting point between 105-115°C and can be reshaped after heating, making it suitable for blow molding and extrusion processes. It is very flexible and not easy to break, making it particularly suitable for packaging materials that require lightweight and bendable.
Is Silicone A Thermosetting Plastic?
Silicone is a thermosetting elastomer that cannot be reshaped after curing. It has excellent high temperature resistance and can withstand temperatures above 250°C, so it is often used in medical devices, seals, and kitchenware. For example, I chose silicone material when making high-temperature seals because it is not only heat-resistant but also maintains good elasticity and sealing. In addition, silicone has good biocompatibility. I found in the production of medical-grade silicone catheters that it can be in contact with the human body for a long time without causing allergic or toxic reactions.
Is HDPE A Thermoset?
HDPE (High-density polyethylene) is a thermoplastic that I often use in the manufacture of industrial pipes and tanks. HDPE has a melting point between 130-135°C and excellent chemical resistance, making it suitable for chemical tanks and water pipes. Compared with LDPE, HDPE is more rigid and less prone to deformation.
Is PLA A Thermoplastic?
PLA (polylactic acid) is a thermoplastic that I use extensively in 3D printing and the production of biodegradable packaging materials. It has a melting point between 150-180°C and can be shaped by heating, making it suitable for FDM 3D printers. However, PLA has a low heat resistance and may deform above 60°C, so it is not suitable for high temperature environments.
Cまとめ
In the manufacturing process, I often need to choose between thermoplastics and thermosets. Their respective characteristics determine the different application scenarios . Understanding the characteristics of these two materials can help engineers and manufacturers make more informed decisions and improve production efficiency and product quality. I hope that through this guide, you can more clearly judge which material is more suitable for your project and get better results in future processing choices.