Everything You Need to Know About Acrylic Melting Point

People in the construction, automotive, art, and design industries revolutionized how acrylic is used in their operations by creating new innovative technologies for its use. But for the best application and performance, understanding its thermal properties, specifically the melting point, is equally important. This post covers the science of acrylic’s melting behavior and heat response and discusses why “melting point” is a misnomer for a thermoplastic material like acrylic. By the end of this post, whether you’re an acrylic professional or just someone interested in its properties, you will have the useful information to make guided choices on the matters at hand.

What is the acrylic melting point?

Unlike other materials, acrylic lacks a distinct melting point That is, it exhibits something called a glass transition temperature (Tg), which is usually between 100 Celsius to 110 Celsius (212 °F to 230 °F). Acryllic softens and becomes easier to work with at this thermoplastic Tg, instead of transforming into liquid. This is the reason thermoplastics are preferable in processes like shaping and forming under controlled heat, therefore acrylic is suitable for these processes.

Understanding melting temperature and its significance

The melting temperature is defined as the temperature at which a material will turn from a solid state to a liquid state within standard conditions. The melting point is critical in determining the applications of a material as it sets the temperature limit beyond which the material can deform or lose its structural integrity. Well-defined melting point materials like metals are preferred for high temperature applications due to their stability while materials like thermoplastics that do not have a sharp melting point are valued for their ease of processing under heat. As for engineering, manufacturing, and product design, melting temperature is key in understanding material selection.

Comparing the melting point of acrylic with other plastics

Acrylic is classified as a thermoplastic, with the common name polymethyl methacrylate (PMMA) for other uses. The melting temperature of acrylic is low compared to other plastics. Depending on the composition and grade, acrylic softens between 85°C and 165°C (185°F and 329°F). This feature is useful in applications that require moderate thermal stability, such as signage, displays, and lightweight glazings.

For comparison, polycarbonate (PC) is another popular plastic, and it has a softening range between 150°C to 160°C (302°F to 320°F) which is a lot higher than that of acrylic. Because of this, polycarbonate becomes the most suitable choice for applications that require high resistance to heat – safety equipment or lighting fixtures.

On the contrary, plastics like polyethylene (PE) have a very low melting point, which ranges from 110°C to 130°C (230°F to 266°F) for high–density polyethylene (HDPE). Even with this, polyethylene has a wide range of properties that make it desirable for piping and packaging solutions. Another polymer that is widely used is polystyrene (PS) which has a melting range of about 100°C to 120°C (212°F to 248°F) which is closer to acrylic.

Acrylic is clearly the material of choice for applications that require moderate temperature resistance, transparency, and easiness to machine because acrylic demonstrates thermal stability. Mechanical strength, thermal exposure, and the nature of the environment will determine how acrylic and other plastic materials will be used.

Factors affecting acrylic melting behavior

Acrylic melt behavior is affected by molecular structure and composition, surrounding environment, and heating methods previously used. Its glass transition temperature (Tg) of around 95 to 105 degrees Celsius is primarily influenced by acrylic’s main constituent, polymethyl methacrylate (PMMA). Factors that affect melting behavior comprise of:

Molecular Weight

Acrylic with a higher molecular weight softens at higher temperatures and is more thermally stable. This is further caused by additional chains within the molecules which require more energy to break and deform.

Additives and Fillers

Modification of acrylic formulation by the addition of stabilizers or fillers greatly enhances its melting and thermodynamic properties. Stabilizers can enhance heat resistance, whereas plasticizers make the acrylic softer at lower temperatures due to lowering Tg.

Heating Rate

The rate of temperature increase during processing can affect the thermal behavior of acrylic particularly on the impact of polymerization. Increasing the temperature too quickly risks melting the material unevenly and degrading the material, while gradually increasing the temperature gives more control over the solid-state softening.

Environmental Factors

Acrylic is exposed to UV radiation or humid environment over time makes the polymer chains degrade which changes thermal behavior. UV radiation increases the rate of degradation and reduces thermal resistance which accelerates the process.

Methods And Processes

Methods like laser cutting or thermoforming utilize heat in a regulated manner. In these methods, localized overheating over the set limit can lead to deformation, charring, or bubbling of the material in the heating range of its processing temperature.

Recent studies using thermogravimetric analysis TGA indicate that the decomposition temperature for PMMA is between 280 to 300 degrees Celsius and 536 to 572 F which indicates fairly good resistance to thermal degradation before complete breakdown. Therefore, knowing these factors is necessary for the optimum use and behavior of acrylic in different thermal environments.

How does acrylic plastic perform in injection molding?

Role of mold temperature in plastic injection molding

Mold temperature is one of the key parameters in the plastic injection molding process that has a direct relation with the quality, strength, and appearance of the product. For materials such as acrylic (PMMA), the degree of mold temperature greatly determines its optical clarity, surface finish, and even its dimensions. Typical values for PMMA are 65°C and 85°C (149°F to 185°F) although this may vary with the grade of the material and its intended application.

Higher mold temperatures improve the flow of molten polymer thus internal stresses are minimized and part integrity is enhanced. Excessively high mold temperatures, however, impact cooling times which can negatively affect cycle efficiency and production rates. Alternately, lower mold temperatures can lead to incomplete filling, poor surfaces, and inferior mechanical properties of the molded parts. As with any other plastic, proper temperature control, combined with optimized injection and cooling cycles, is needed to achieve the desired functional and aesthetic properties within acrylic components.

Temperature range considerations for PMMA

The ideal mold temperature for PMMA is usually between140°F to 200°F (60°C to 95°C). Remaining within this range helps achieve optimal surface finish, clarity, and dimensional stability of the molded parts. Most applications would do well with a temperature closer to the upper end of the range because it would improve mechanical properties and minimize build defects such as incomplete filling. However, for specific material grades and part requirements, the best results would need fine-tuning of the exact temperature.

Common issues in injection molding acrylic

The injection molding of acrylic results in durable and high-quality parts; however, with uncontrolled parameters, numerous problems may occur. Here, we illustrate some of the issues, provide their reasoning, and propose resolutions:

Warpage and Dimensional Instability

Warping can be caused by differential cooling rates or part stresses. Acrylic has a high cooling shrinkage that ranges from 0.2% to 0.8% which creates internal stresses that can lead to warping during cooling. To minimize warpage, the mold must thoroughly cool by optimizing mold design, incorporating suitable cooling channels, and controlling mold temperatures for polycarbonate and acrylic applications. In addition, material drying should also be controlled since moisture left in the material can lead to additional internal stresses.

Brittleness and Cracking

Plexiglass parts are known to be brittle and crack-prone, especially under high strain or incorrect processing conditions. This is often the result of insufficient material drying. Acrylic as a hygroscopic material will absorb moisture from the environment; without adequate drying, parts are prone to moisture-induced degradation during molding. To mitigate this risk, the material should be pre-dried for 2-4 hours at a temperature of 80-90 degrees Celsius.

Flow Marks and Surface Defects

Surface defects generally occur with either low injection pressure or incorrect mold and melt temperatures, such as surface blemishes. Mold temperatures for injection molding acrylic are required to be around 60 degrees Celsius to 90 degrees Celsius (140 degrees Fahrenheit to 194 degrees Fahrenheit), while a melt temperature of 200 degrees Celsius to 250 degrees Celsius (392 degrees Fahrenheit to 482 degrees Fahrenheit) is optimal. Eliminate the flow rate and pressure for these temperatures to deal with them effectively.

Incomplete Filling or Under-Filling

Some acrylic components may appear underfilled due to low injection pressure, low met temperature, or poor venting. Acrylic requires high injection pressures to fill cavities effectively. Properly monitor pressure injection while designing and placing vents where they can allow trapped air to bubble out.

Burn Marks and Discoloration

Burn marks are either a result of trapped air pockets that overheat in the cavity, or excessive melt temperature degrading the material. Burns and discoloration especially in Polycarbonate and acrylic, can be avoided by lowering venting systems and adjusting the melt temperature. Ensure the material is oxidized or contaminated to ensure proper handling.

Sink Marks and Voids

Sink marks and voids are imperfections that arise due to inadequate packing pressure during the molding stage or improperly controlled cooling rates. Increasing packing pressures while improving cycle times can help eliminate these defects. Furthermore, try maintaining uniform wall thicknesses throughout the part to allow for uniform cooling.

If these challenges are handled with systematic control and optimization of the process parameters, sink marks, and voids can be eliminated, thereby improving part quality and achieving better consistency while injection molding acrylic materials. Mold upkeep and following guidelines pertaining to the specific grade of material are, of course, essential to reduce defects.

What are the properties of acrylic that influence its melting point?

Physical and mechanical properties of acrylic

While these materials are best known under their commercial name Lucite, Acrylic’s chemical composition is that of polymethyl methacrylate or PMMA. Acrylic’s clear optical characteristics are only matched by its thermoplasticity, making it light and easy to mold to desired shapes. Its versatility is also enjoyed when it comes to weather resistance and durability. Acrylic also has a density of about 1.18 g/cm³ which is more than 20% less than glass while having nearly the same refractive index of 1.49. When compared to other thermoplastics, acrylic has quite remarkable mechanical properties which include a tensile strength of 50 to 70 MPa, and flexural strength of 75 to 110 MPa.

Unlike glass acrylic is relatively strong, but is not as strong as polycarbonate. Acrylic is estimated to have a modulus of elasticity within the range of 2,400 to 3200 MPa which indicates moderate to good rigidity while having enough flexibility for structural use. It is a relatively easy process to convert acrylic into a thermoformed item as it requires 160 degrees Celsius (320 degrees Fahrenheit) to most easily mold it.

Because of the low moisture absorption of acrylic materials, around 0.2 – 0.3 % at equilibrium, they are highly stable dimensionally and resistant to warping. Moreover, this material has good UV stability as well as weathering resistance which makes it useful for outdoor applications for a longer period. In addition to those properties, Acrylic is also resistant to a wide range of chemicals such as acid and alkali as well as being easily machinable and customizable to various shapes and finishes. All of these properties make acrylic the preferred material for many industries such as automotive, construction, and consumer goods.

Impact of polymer composition on melting temperature

A polymer’s melting temperature corresponds with its molecular composition and structure. Amorphous regions of a polymer that result from a more random molecular configuration frequently have lower melting temperatures than polymer crystalline regions that result from ordered molecular chains. For instance, linear polymers such as polyethylene which have low levels of branching, have higher crystalline content, and thus, higher melting temperatures.

Copolymers also have an important effect on the melting temperature. The introduction of comonomers containing different chemical groups disrupts the uniformity of molecular order, leading to lower melting temperatures. The incorporation of ethylene comonomers into polypropylene results in a random copolymer that is more flexible and easier to process due to lower melting temperatures.

Moreover, functional groups and additives can further change the thermal performance of the polymer by modifying the intermolecular forces. For example, polymers containing polar groups such as polyamide (nylon) are known to hydrogen bond to one another more strongly than nonpolar polymers such as polyethylene which makes their melting point higher.

Experimental studies indicate that the molecular weight also has a significant impact. An increase in molecular weight is usually associated with a slight increase in melting temperature as stronger van der Waals forces act between longer polymer chains. However, after a certain molecular weight is reached, there is no further increase in melting temperature.

These arguments illustrate the need to design polymer compositions with accurate control of chain length, branching, and the incorporation of comonomers or functional side groups to achieve target thermal characteristics for particular industrial purposes.

How methyl methacrylate affects acrylic performance

Methyl methacrylate, or MMA, serves a significant purpose with regard to acrylic materials exhibiting performance characteristics. As a primary monomer in the production of polymethyl methacrylate (PMMA), MMA integrates optical clarity, weather resistance, and mechanical strength in the material. One of the most noticeable characteristics of acrylic MAA is its unparalleled transparency, in which the light transmission rate is roughly 92%, exceeding that of glass. Additionally, combined with outstanding UV resistance, these acrylics are perfect for outdoor applications such as signage, glazing, and even automotive parts.

Acrylic polymers tend to incorporate methyl methacrylate, which aids in increasing impact resistance and tensile strength. It is known that, on average, PMMA has a tensile strength of 50 to 75 MPa, based on the formulation and processing conditions. Other than that, changes to MMA ratios or copolymerization with other monomers can serve specific needs such as flexibility or better chemical resistance.

MMA’s impact on structural acrylics goes beyond composition. Thermal stability is also an important consideration. Standard PMMA grades have a high glass transition temperature of around 105°C, which can allow for the use of acrylics in environments with drastic temperature changes. Plus, MMA’s chemical structure provides high resistance to degradation from prolonged exposure to sunlight and other environmental factors which ensures enduring performance.

Performance efficiency, in combination with their lightweight factor, makes MMA-based acrylics more applicable. Their density is almost half that of glass, which decreases material costs and improves the ease of handling the acrylics. This, coupled with the recyclability of MMA-based acrylics, contributes to the increased usage of acrylic materials in different industries, ranging from architecture to consumer goods.

How do acrylic and polycarbonate compare?

Difference between acrylic and polycarbonate in terms of melting point

Acrylic (polymethyl methacrylate) and polycarbonate are both widely used thermoplastics, however, these two have great differences especially when it comes to their thermal properties; for example, their melting point. Acrylic does not have a true melting point, but rather, softens within the range of 160°F to 220°F (70°C to 105°C), depending on the specific formulation. Such a range of softening makes acrylic less applicable in other fields that require resistance to very high temperatures.

In contrast, polycarbonate exhibits superior thermal performance. It also has a higher softening temperature and much higher glass transition temperature of about 297°F (147°C), which is critical when considering temperatures in the context of different plastics. This much higher limit makes polycarbonate exceptionally more thermally stable as it can endure extended exposure to elevated temperatures without losing structural integrity. This makes polycarbonate ideal for use in highly demanding applications such as automotive components, electronic device housings, and various protective gear.

These differences when it comes to thermal acrylic and polycarbonate thermoplastics are critical because when selecting materials based on the required operational environment temperature requirements, polycarbonate is the more reliable choice in instances of elevated heat.

Applications of acrylic and polycarbonate based on temperature range

Acrylic

• Moderate Temperature Applications (up to 190°F/88°C)
• Display Cases and Shelving: With rivalry between acrylic and polycarbonate stands out for both materials. Other comparations suggest that Acryl and its low cost, and competitiveness make it ideal for indoor display cases and shelving with stable temperature fluctuations microwave ovens, and refrigerators.
• Signage and Lighting Fixtures: It is also used to make decorative signs and for lighting lamps, where used are not subjected to very high temperatures.
• Aquariums and DIY Projects: For low heat creating applications and readily for accessory-based construct designs.

Polycarbonate

• High-Temperature Applications (up to 297°F/147°C)
• Automotive Components: Polycarbonate is common for use on headlight lenses, instrument panels, and engine covers because of the high operating temperature they need to withstand
• Electronic Device Housings: Used for enclosures of laptops, smartphones, and industrial equipment because the electronic devices generate heat.
• Protective Equipment: Used in goggles, face shields, and helmets due to the thermal resistance and impact strength.
• Construction Materials: For roofing panels or skylights that are constantly exposed to sunlight heat and changes in temperatures.

The application of acrylics and polycarbonates is influenced by their unique thermal properties, reinforcing the need for aligning operational temperature requirements with the appropriate material.

Choosing the right clear plastic for your needs

When picking the most suitable type of clear plastic, I take into consideration the exact requirements of my use case. In case I require a material that has a polycarbonate melting and has very high impact resistance and long wear durability, I usually choose polycarbonate. Conversely, in some outdoor applications where better UV resistance and optical clarity is required, I prefer acrylic. Besides these two, cost, weight, and thermal characteristics are also important for the intended application, and these factors must be analyzed as well. Knowing these attributes and how to relate them to the operational parameters of my project is critical.

What are the practical applications of acrylic with its melting point?

Using acrylic sheets in different environments

Acrylic sheets can serve many functions depending on the environment. Their outstanding UV resistance and weathering make it effective for outdoor use, where it is often used as a protective barrier, signage, and windows, especially in the UK where it comes with a 20-year warranty of any kind. Indoors, they are extensively used for display cases, furniture, and light furnishings due to their clarity and lightweightness. Acrylic melting point of approximately 320F means it can sustain moderate heat, but is unsuitable for high-temperature applications, which means that usage conditions have to be adapted to its thermal restrictions.

Considerations for CNC machining acrylic

With CNC machining of acrylics, tooling, and cutting parameters must be done with care to prevent chipping or cracks. For polished finishes and clean cuts, Sharp, high-grade carbide or diamond-coated tools are recommended. Chipping is common with overheating, thus, higher spindle speeds and lower feed rates provide a smooth and efficient machining operation. Furthermore, proper cooling techniques like mist or air cooling need to be implemented to prevent melting or deformation. Secured clamping further reduces vibrations and improves accuracy in the machining process. These are the most basic practices and with accurate preparation, the performance of CNC machines along with the quality of the products is greatly improved.

Advantages of acrylic in impact resistance scenarios

Impact strength plays an important role when choosing polycarbonate or acrylic for different applications.

As an example, acrylic is still much more plastic and apt for certain uses as it shatters with approximately ten times the impact resistance of standard glass. This quality makes acrylic a superb option in scenarios where durability is of utmost importance. Knowing this, by shattering, acrylic’s ability to withstand force minimizes risk while increasing application longevity.

Lightweight Durability

Acrylic polymers are also pretty lightweight compared to glass of the same and have even lower impact resistance, as they are routinely approximately 50% lighter. This quality makes acrylic ideal for applications like automotive, aerospace, and portable devices, where weight is a critical factor.

Crack Propagation Resistance

Acrylic thermoplastic can resist crack propagation, which allows it to endure minor structural damage without losing integrity. This property makes it extraordinary in harsh environments where reliable performance is essential like protective barriers and even structural glazing.

Temperature Dependence of Impact Strength in Different Plastics

Several studies have been conducted on acrylic and it is proven that, as opposed to other plastics, acrylic retains intact sturdiness through all climatical temperatures – making it ideal for indoors and outdoors, with some recording range of -20 degrees celcius and going all the way up to 60 degrees, showcasing good performance through most environmental conditions.

Compatibility of Materials

Acrylic plastic is durable enough to withstand UV light along with the common chemicals that typically break down impact-resisting materials. These factors enhance its reliability and usability in various industrial and commercial settings.

Flexibility in Shapes

Because of its excellent machinability and ability to be molded into complex shapes, acrylic is custom molded for impact-resistant features such as safety shields, guards for machines, and sporting equipment without loss of structural integrity.

Acrylic boasts a unique combination of impact strength, lightweight, and durability which makes the material superior across a wide range of demanding applications. Such characteristics make acrylic a reliable substitute in safety-critical situations when compared to materials such as polycarbonate or glass.

Frequently Asked Questions (FAQs)

Q: What is the melting temperature of acrylic?

A: Polymethyl methacrylate, or acrylic, has a melting temperature between 160 °C and 180 °C. As a thermoplastic, it softens before it melts which allows it to be used in many different ways.

Q: How does the melting point of acrylic compare to other plastics?

A: Acrylic, or PMMA, has a lower melting temperature than another type of plastics such as polycarbonate or Lexan. For example, Polycarbonate has a melting temperature of about 155 °C – 160 °C which makes it relatively easy to deform acrylic with heat.

Q: What types of acrylic are most common?

A: Cast and extruded acrylic are the most common types. Both types of acrylic have differences in their physical properties and way of production that can impact how they melt as well as how they can be used.

Q: Can acrylic be used in high UV environments?

A: Yes, acrylic can withstand high levels of UV radiation due to having good UV resistance. That being said, some types of acrylic may yellow after being exposed to UV light for a long time which is something that should be looked at depending on how the acrylic is to be used.

Q: In what ways does the glass transition temperature of acrylic influence its use?

A: Acrylic indeed has a glass transition temperature of about 105 °C. This is the temperature at which the material begins to soften, which is vital to know concerning the polycarbonate melting point. The glass transition temperature is significant for thermally resistant applications since it determines how an acrylic piece can be utilized.

Q: Is it possible to utilize acrylic in 3D printing?

A: Certainly, specific forms of acrylic can be utilized for 3D printing. Acrylic filament is used in FDM 3D printers and offers great finish and clarity, although its specific temperature along with physical properties makes it necessary to handle with care.

Q: How does the melting point of acrylic affect its processing?

A: Acrylic’s melting point changes the ways it can be processed since it controls the melting and setting temperature ranges of the material. It is important to control temperatures to not exceed desired values which may result in unwanted softening or reshaping of the plastic.

Q: What are the effects of solvents on acrylic?

A: Depending on the type of solvent, and its duration of exposure, solvents can soften or even dissolve acrylic. While this can help in fulfilling some applications, handling is sensitive to maintaining the integrity of acrylic material.

Q: How can a temperature chart assist in working with acrylic?

A: The chart can be used to assist with optimal melt-to-heat cycles or cooling periods of acrylic helping to eliminate the chances of plastic material melting ensuring the best results when working with this type of plastic.

Q: In what ways does Xometry assist in acrylic projects?

A: Xometry’s support in acrylic projects includes recommending the appropriate material, processing custom manufacturing capabilities, and offering design support so the correct type of acrylic and processing are applied.

Reference Sources

1. The Research of Melting and Heat Transfer Phenomenon of Urea Water Solution With Respect To Operating Conditions of A Heating Module In A Frozen Urea Tank

• Author(s): Byeong-Gyu Jeong and others.
• Date Published: 06 December 2021
• Citing: The melting and heat transfer phenomenon is examined with an emphasis on its operating conditions ((Jeong et al, 2021) ).

Overview:

• The frozen urea water solution (UWS) melting study encompasses the process of a heating device’s operation and is integral for the practical realizations of the melting point shifts.

Important Developments:

• The melting features depend on the design of the heating module and the UWS’s initial values.
• Gives detail for improving the melting process in urea-selective catalytic reduction systems or onboard systems that have battery electric vehicles.

Research Design:

• The researchers designed a tank for a urea solution and investigated the melting features by changing the heating module’s parameters and recording the time evolution of the temperature fields.

2. Hydrogel that contains acrylic coumarin and acrylic Pluronic F-127 and its release properties photo and thermally responsive

• Authors: D. Yoon, Jin-Chul Kim
• Publication Date: 09.09.2017 (not within the last 5 years, but relevant)
• Citation Token: (Yoon & Kim, 2017, pp. 481–488)

Summary:

• This article deals with the properties of a hydrogel formed from acrylic constituents and its melting point together with the hydrogel’s responsiveness towards changes in the surrounding environment.

Key Findings:

• The hydrogel showed remarkable alterations in its melting point and release characteristics under certain conditions, which suggests the possibility of utilizing this for drug delivery systems.

Methodology:

• The experiment consisted of the hydrogel synthesis and the testing of its thermal and photo-responsive properties.

3. Mechanistic Studies and Kinetic Analysis of By-Product Formation in the Storage of Pure and Aqueous Acrylic Acid. 

• Authors: C. Pfeifer et al.
• Publication Date: 2017-04-01 (dated, yet relevant)
• Citation Token: (Pfeifer et al., 2017, pp. 755–759)

Summary

• The research examines the problem of by-product formation during the storage of acrylic acid, which as an acid is relevant in understanding the melting point and stability of acrylic materials.

Conclusions:

• In this study was evidence that water is important for the by-product formation, which in turn influences the melting point and quality of the acrylic acid.

Methodology

• Kinetic measurements of the by-products were measured at different temperatures to study the by product formation mechanisms.

4. Poly(methyl methacrylate)

5. Plastic