Polyvinyl chloride (PVC) is a widely used thermoplastic polymer that plays an important role in many industries such as construction, medical, electronics, and automobiles. Since the melting point of PVC is not a single temperature, but a melting range, an accurate understanding of its melting characteristics is crucial for optimizing processing conditions and improving product quality. I will take you to an in-depth understanding of the melting point, influencing factors, processing conditions, and comparison with other thermoplastics of PVC to help you better master the application and optimization strategy of this material.
Ce qu'il faut faire Is PVC?
Polyvinyl chloride (PVC) is a widely used thermoplastic plastic, which is polymerized from vinyl chloride monomer (C₂H₃Cl) . Depending on the content of plasticizer, PVC can be divided into rigid PVC (RPVC) et soft PVC (FPVC) . The former is rigid and resistant to high temperatures, suitable for pipes and window frames, while the latter is soft and elastic, and is often used in wire sheaths, medical tubing, etc.
The melting range of PVC is usually 100–260°C , of which the melting point of rigid PVC is 170–212°C, while the melting point of soft PVC is 160–190°C. Chlorinated PVC (CPVC) has the highest melting point, which can reach 230–260°C. Since PVC may begin to decompose at 140–150°C , heat stabilizers need to be added during processing to prevent degradation. In addition, PVC has good flame retardancy and electrical insulation properties, but its heat resistance is limited. The long-term temperature resistance of ordinary PVC usually does not exceed 80°C, so modified PVC, such as CPVC or specially formulated PVC materials, need to be selected in high temperature environments.
What Is Til Melting Point Of PVC
The melting point of polyvinyl chloride (PVC) is not a fixed value like that of metals, but a wide melting temperature range. This is mainly due to the influence of PVC’s molecular structure and additives, which makes its melting process not a simple transition from solid to liquid, but a process from glass transition to softening and then to complete melting. In actual production, the melting point of PVC is usually between 100°C and 260°C , but the specific temperature depends on the type of PVC, molecular weight, processing method and additive content.
In my actual production experience, different types of PVC exhibit significantly different melting characteristics during processing. For example, when producing PVC pipes by extrusion, it is crucial to control the melting temperature. If the temperature is too low, the material cannot be fully melted, resulting in an uneven internal structure of the product and reduced strength. If the temperature is too high, it may cause PVC to decompose and release harmful gases such as hydrogen chloride (HCl), affecting product quality and production safety. Therefore, precise temperature control is crucial to the quality of PVC products.
Different types of PVC have different melting temperature ranges, which mainly depend on their molecular structure, plasticizer content and other modified ingredients :
| PVC Type | Melting point range (°C) | Main application areas |
| Rigid PVC (RPVC) | 170–212 | Building pipes, window frames, profiles, automotive parts |
| Flexible PVC (FPVC) | 160–190 | Wires and cables, medical equipment, inflatable products |
| Chlorinated PVC (CPVC) | 230–260 | Hot water pipes, chemical pipelines, high temperature cable sheaths |
Rigid PVC (RPVC): Melting point is 170–212°C.
This type of PVC has no or only a small amount of plasticizer, so it has high rigidity and heat resistance, and is suitable for high-strength applications such as building pipes and window frames. RPVC has a higher melting point, so it requires higher extrusion or injection molding temperatures during processing. For example, when producing PVC drainage pipes, we usually set the extruder processing temperature at 180–190°C to ensure uniform melting of the material while avoiding decomposition.
Flexible PVC (FPVC): Melting point is 160–190°C.
Due to the addition of plasticizers (such as phthalates or DOTP), the melting temperature of flexible PVC is relatively low, giving the material better flexibility. It is widely used in wire and cable sheathing, medical catheters, inflatable toys, etc. Taking medical-grade PVC pipes as an example, a processing temperature of 170–180°C is usually used to maintain the flexibility of the material while ensuring that the mechanical strength meets medical standards.
Chlorinated PVC (CPVC): Melting point 230–260°C.
By chlorinating PVC, CPVC has higher heat resistance and chemical resistance, and is particularly suitable for high-temperature piping systems. In practical applications, such as hot water pipes and chemical pipes , we will control the extrusion temperature at around 240°C to ensure its good thermal stability.
Glass Transition Temperature (Tg) Of PVC
Glass transition temperature (Tg) is an important parameter to measure the thermal properties of polymers. It indicates the temperature at which a material changes from a rigid solid state to a rubbery state with a certain elasticity. For PVC, Tg is usually between 82–87°C .
Effet Of Tg Value On PVC Performance:
Le Higher The Tg , the harder and more rigid the PVC is, the better the heat resistance is, but the toughness is reduced. For example, the Tg of RPVC is close to 87°C , which allows it to maintain structural stability in high temperature environments , but may become brittle under low temperature conditions.
Le Lower The Tg , the more flexible the PVC is, making it suitable for making products that require high ductility, such as hoses, wire sheaths, etc. For example, the Tg of FPVC is generally between 60–75°C , it can still maintain a certain softness in cold weather.
Le Influence Of Tg Value On Practical Application:
- In the construction field, PVC window frames are required not to deform under high temperatures in summer , so high Tg RPVC is usually used.
- In the medical industry, PVC infusion tubing is required to remain flexible at low temperatures, so low Tg FPVC is used.
- In the automotive industry, PVC dashboard materials need to be able to withstand high temperatures but not harden and crack due to low temperatures . Therefore, modified PVC materials with a Tg between 70–85°C are selected .
During the development of a cable sheath material, I encountered an interesting problem: the PVC material initially selected showed brittle cracking below -10°C, while the customer’s use environment required the product to remain flexible at -20°C. In the end, we successfully solved the low-temperature brittleness problem by adjusting the plasticizer content to reduce the Tg to 60°C , while still maintaining high heat resistance and mechanical strength.
Factors Affecting Til Melting Point Of PVC
The melting characteristics of polyvinyl chloride (PVC) are affected by the combined effects of molecular weight, plasticizers, additives, fillers, and processing environment. Proper control of these variables can not only optimize the processing performance of PVC, but also prevent degradation and improve the quality and durability of the final product.
For example, when producing high-heat-resistant PVC pipes, we need to select appropriate additives and control the processing temperature to ensure the stability of the product in high-temperature environments. A deep understanding of these influencing factors can help us make the best material selection in different application scenarios.
Molecular Weight And Polymer Structure
The molecular weight of PVC has a direct influence on its melting behavior. Typically, the number average molecular weight of PVC ranges from 30,000–150,000 g/mol. The higher the molecular weight, the stronger the forces between the polymer chains, the higher the melting temperature, and the better the mechanical properties and heat resistance.
The melting temperature of high molecular weight PVC is generally between 200–260°C, which is suitable for high strength and high heat resistance applications such as building pipes, automotive interior parts and industrial panels. However, high molecular weight PVC is more difficult to process and requires higher processing temperature and longer melting time.
Low molecular weight PVC has a lower melting temperature, usually between 160–190°C, and is suitable for applications that require good fluidity and flexibility, such as cable sheathing, hoses, and film materials. This type of PVC has excellent processing performance and fast molding speed, but its heat resistance and mechanical strength are relatively low.
In an automotive sealing strip production project, we used high molecular weight PVC to improve wear resistance and strength. However, due to the high melting temperature, the processing difficulty increased and the production efficiency dropped by 20%. In the end, we chose medium molecular weight PVC and adjusted the processing temperature, which increased the production efficiency by 15% while maintaining the durability of the product.
Effet Of Plasticizer On Soft PVC
The melting point of soft PVC is greatly affected by the plasticizer content. The function of plasticizer is to reduce the interaction between polymer molecular chains, making PVC softer and lowering the melting temperature. In soft PVC, the plasticizer content is usually between 10-50%.
At low plasticizer contents (10-20%), PVC has a melting point of about 180–190°C and is suitable for semi-rigid applications such as cable jacketing and weatherstripping. At higher plasticizer contents (30-50%), the melting point of PVC can be lowered to 160–180°C, making it suitable for flexible films, medical tubing and hoses.
Communs plasticizers include phthalates (such as DOP, DINP) and environmentally friendly plasticizers (such as DOTP, ESBO). Traditional plasticizers can significantly reduce the melting point of PVC, but there may be environmental and health risks, so non-toxic and environmentally friendly plasticizers are generally used in the medical and food industries.
In the production of medical catheters, we tried to use 30% DOTP plasticizer to reduce the melting point of PVC to 165°C and improve the fluidity of the material. Ultimately, the transparency and softness of the catheter were optimized, while the production efficiency was increased by 15%.
Effects Of Additives And Fillers
In order to optimize the processing performance and finished product characteristics of PVC, stabilizers, flame retardants and fillers are usually added during the production process. These ingredients not only affect the heat resistance of the material, but also have a direct impact on the melting behavior.
Thermal stabilizers (such as calcium zinc stabilizers and lead salt stabilizers) are used to improve the heat resistance of PVC and prevent decomposition during high-temperature processing. Studies have shown that adding 1-3% calcium zinc stabilizer can increase the thermal decomposition temperature of PVC from 180°C to 220°C, effectively extending the processing window and improving production stability.
Flame retardants (such as antimony trioxide and aluminum hydroxide) can enhance the fire resistance of PVC. In applications such as wire and cable sheathing, adding 5-10% antimony trioxide can increase the limiting oxygen index of PVC by 5-8%, reducing the risk of flame propagation.
Fillers (such as calcium carbonate, talc) are often used to reduce costs while improving the rigidity and dimensional stability of products. Calcium carbonate content of 10-30% will not significantly affect the melting point of PVC, but if it exceeds 40%, it may cause the melting temperature to rise by 5-10°C and reduce the impact strength of the material.
In one PVC flooring production process, we used 20% calcium carbonate filler, which reduced the material cost by 15% while maintaining good processing properties and mechanical strength. However, when the filling amount was increased to 35%, it was found that the melting temperature rose by 8°C and the processing difficulty increased. Finally, we chose a filling ratio of 25% to ensure the best balance between production efficiency and finished product quality.
Processing Conditions And Environmental Factors
The melting behavior of PVC is not only affected by the material itself, but also by processing conditions and environmental factors. During the production process, reasonable control of these factors can optimize the melting characteristics of PVC and improve the quality of the finished product.
Heating rate is a key variable. If the heating speed is too fast, it may cause PVC to decompose, release HCl gas, and affect the quality of the product. Therefore, in PVC extrusion processing, the recommended heating rate is no more than 10°C/min to ensure uniform melting and prevent material degradation.
Oxygen exposure can also affect the melting behavior of PVC. Under high temperature conditions, PVC exposed to oxygen may undergo oxidative degradation, resulting in color changes and loss of mechanical properties. During PVC processing, 0.5-2% antioxidants such as BHT are usually added to reduce the risk of oxidative degradation.
Humidity is also a factor that needs attention. Although PVC itself has low hygroscopicity, high humidity environment may affect the stability of plasticizers and stabilizers, thereby changing the melting characteristics. Before injection molding, we usually recommend drying PVC materials at 80°C for 2-4 hours to ensure processing stability.
During the production of PVC building pipes, the material partially decomposed due to the excessively fast heating rate, resulting in a large amount of smoke in the extruder. After adjusting the heating curve, we successfully controlled the extrusion temperature at 185°C, which significantly improved the surface quality of the finished product and reduced the scrap rate by 30%.
Comparison Of Melting Points Of PVC And Other Thermoplastics
Polyvinyl chloride (PVC) plays an important role in the plastics industry. Its melting point (160–212°C) is higher than that of polyethylene (PE) and polypropylene (PP), but lower than that of polystyrene (PS) and chlorinated polyvinyl chloride (CPVC). In addition, PVC excels in chemical resistance and rigidity, but its heat resistance is inferior to that of CPVC. In the manufacturing process, the rational selection of materials can not only improve processing efficiency, but also ensure the stability and durability of the product in the final application.
| Material | Melting point (°C) | Glass transition temperature (Tg, °C) | Decomposition temperature (°C) | Key Features |
| PVC | 160–212 | 82–87 | 140–150 | Excellent chemical resistance, good rigidity, suitable for pipes, cable sheaths, etc. |
| CPVC | 230–260 | 100–120 | 200–220 | The heat resistance is much higher than PVC and is widely used in high-temperature water pipes and industrial equipment. |
| PP | 130–171 | -10 | 280–300 | Lightweight, good fatigue resistance, often used in packaging and medical devices |
| PE | 110–135 | -20 to -30 | 290–310 | Strong flexibility, chemical resistance, suitable for films, pipes, etc. |
| PS | 210–249 | 100 | 260–300 | High hardness, excellent transparency, widely used in packaging and electronic products |
What Are Til Rocessing Methods Of PVC ?
Polyvinyl chloride (PVC) is widely used in the construction, automotive, medical, electrical, packaging and other industries due to its good processability, mechanical properties and chemical resistance. The melting point of PVC (160–212°C) determines its processing method, which in turn affects the performance and use of the final product. Rigid PVC (RPVC) is mainly used for pipes, profiles and automotive parts, while soft PVC (FPVC) is often used for wire insulation, medical devices and packaging films due to its flexibility.
Extrusion (160–190°C)
Extrusion is one of the most common methods of PVC processing and is suitable for producing products with continuous cross-sections such as pipes, wire jacketing and sealing strips.
- Process principle : After the PVC particles are melted at a temperature of 160-190°C, they are pushed to the mold by the extruder and shaped into the final product by cooling.
- Applicable products : water supply and drainage pipes, cable sheaths, building profiles, industrial sealing strips.
- Advantages :
- Produces continuous lengths, suitable for mass production.
- It can achieve precise control of size and wall thickness and improve product consistency.
- It can be used in conjunction with co-extrusion technology to manufacture multi-layer composite products to improve weather resistance and mechanical properties.
In the construction industry, PVC pipes are produced using an extrusion process, and the smoothness of the inner wall affects the water flow resistance. We have optimized the extrusion temperature to 185°C, reducing the surface roughness of the product to Ra 0.2μm, reducing scaling on the inner wall of the pipe and improving fluid delivery efficiency.
Injection Molding (170–200°C)
Injection molding is suitable for mass production of PVC products, especially parts with complex shapes and uniform wall thickness, such as pipes, automotive parts, medical equipment housings, etc.
- Process principle : PVC is heated to a molten state at 170-200°C, then injected into a mold under high pressure and formed after cooling.
- Applicable products : pipe fittings, automotive interior parts, medical device housings, electrical switch panels, etc.
- Advantages :
- Suitable for the production of precision parts, the tolerance can be controlled within ±0.1mm.
- It can realize the production of multiple parts at the same time and improve production efficiency.
- It has good repeatability and is suitable for mass production.
In the automotive industry, we have used PVC injection molding technology to produce anti-slip pedals, optimizing the molding temperature to 195°C, which improves the product’s wear resistance by 30% and the surface hardness reaches Shore D 80, meeting the needs of high-intensity use.
Blow Molding (160–190°C)
Blow molding is widely used for hollow structure PVC products such as bottles, containers, tubular packaging, etc.
- Process principle : After heating PVC to 160-190°C, air pressure is used to expand the molten material and form it close to the inner wall of the mold.
- Applicable products : food packaging bottles, chemical storage containers, medical waste bags, industrial liquid storage tanks, etc.
- Advantages :
- Suitable for lightweight products and reducing material waste.
- The production cycle is short, and the molding time of each product is usually 10-30 seconds.
- Suitable for large-scale production and reduces unit cost.
In the food packaging industry, the production of PVC blow-molded bottles must meet strict safety standards. We have optimized the wall thickness of the bottle under process conditions of 180°C, so that the product can pass 50,000 extrusion tests and still maintain its intact shape, improving the durability of the packaging.
Calendering (150–180°C)
The calendering process is suitable for the manufacture of PVC sheets, films and artificial leather, and is often used in building waterproof materials, automotive interiors, advertising light box cloths and other fields.
- Process principle : PVC is melted at a temperature of 150-180°C and continuously calendered through multiple rollers to make the material evenly distributed to form a thin sheet.
- Applicable products : PVC film, advertising cloth, waterproof membrane, artificial leather, floor materials, etc.
- Advantages :
- The thickness of the produced PVC sheets is uniform and the error can be controlled within ±0.05mm.
- It can be compounded with other materials (such as fiber fabrics) to improve tear resistance.
- It is suitable for large-scale industrial production with low unit cost.
In a production project of building waterproof membrane, we optimized the calendering temperature to 175°C, which increased the water pressure resistance of the finished product to 1.5MPa. At the same time, it improved the aging resistance and extended its service life in outdoor environment by more than 3 years.
Le Influence Of Melting Point On PVC Application Selection
The melting point of PVC not only determines its processing method, but also affects the application field of the final product. Low melting point PVC (160–180°C) is suitable for medical equipment and wire insulation , while high melting point CPVC (230–260°C) is suitable for hot water pipes and high temperature resistant industrial parts . PVC materials with different melting points are suitable for different industrial needs. Reasonable selection of materials can improve the performance and durability of products.
Low melting point PVC (160–180°C): suitable for medical devices, wire insulation
- Médical Industry : Low melting point PVC is widely used in medical devices such as IV infusion bags, catheters, dialysis tubes, etc. due to its excellent biocompatibility. For example, PVC catheters molded at 170°C have better flexibility and transparency than other materials and meet ISO 10993 biocompatibility standards.
- Wires And Cables : Soft PVC is widely used in wire sheaths because of its low melting point, which makes it easy to cover metal conductors while providing insulation and heat resistance. For example, a PVC cable sheath molded at 175°C can maintain stable operation in the range of -40°C to 90°C.
High Melting Point CPVC (230–260°C): suitable for hot water pipes, high temperature resistant industrial parts
- Hot Water Pipes : CPVC is used in hot water supply pipes because it has better heat resistance than ordinary PVC and can withstand long-term working temperatures of 80–100°C. For example, in a hotel hot water pipe project, CPVC pipes were used instead of ordinary PVC, extending the life of the pipe system by 40%.
- High-Temperature Resistant Industrial Parts : High-melting-point CPVC is suitable for high-temperature industrial applications such as chemical storage tanks and steam delivery pipelines. Tests show that CPVC chemical storage tanks molded at 240°C can withstand corrosive liquids up to 90°C, while ordinary PVC can only withstand 60°C.
FAQ
What Temperature Does PVC Melt?
From my experience working with PVC, I’ve found that it doesn’t have a sharp melting point like metals but rather softens over a range. Typically, PVC melts between 160–212°C (320–414°F), depending on its formulation. When working with rigid PVC (RPVC), I usually see it maintaining structural integrity at higher temperatures, while flexible PVC (FPVC), due to its plasticizer content, melts at lower temperatures.
What Temp Does PVC Degrade?
In my projects, I always monitor the temperature carefully because PVC starts degrading at 140–150°C (284–302°F), releasing hydrogen chloride (HCl) gas, which can accelerate decomposition. This is why I always incorporate heat stabilizers when processing PVC to ensure it doesn’t break down prematurely, maintaining its mechanical and chemical properties during manufacturing.
Can PVC Withstand Heat?
I often get asked whether PVC can handle high temperatures. From my experience, standard PVC can function continuously at 80°C (176°F) without significant deformation. However, prolonged exposure to higher temperatures will cause softening, warping, or even degradation. When dealing with heat-sensitive applications, I prefer using chlorinated PVC (CPVC), which can withstand up to 100–120°C (212–248°F).
What Is The Softening Point Of PVC?
Softening point is crucial when selecting PVC for specific applications. In my work, I’ve observed that rigid PVC has a Vicat softening temperature of around 82–87°C (180–189°F), making it stable under moderate heat conditions. However, when working with flexible PVC, I notice it softens at 60–80°C (140–176°F) due to the added plasticizers, which make it more adaptable but also more heat-sensitive.
At What Temperature Does PVC Become Soft?
Through hands-on experience, I’ve found that rigid PVC starts softening above 82°C (180°F) , while flexible PVC can become pliable at 60–80°C (140–176°F) . When I design products requiring flexibility at lower temperatures, I opt for plasticized PVC formulations, ensuring they perform well without losing shape or function under moderate heat.
Conclusion
The melting point characteristics of PVC are crucial to its processing and application. The high melting point of rigid PVC makes it suitable for building pipes and window frames, while the low melting point of soft PVC is helpful for medical and wire insulation applications. By optimizing additives and modification technology, the heat resistance and stability of PVC can be improved, expanding its potential in high-end applications. In the future, with the strengthening of environmental regulations and technological advances, the sustainable development of PVC will become the focus of industry attention.