The world of plastics can be a maze of terminologies and types, often leaving the average person bewildered. One such conundrum presents itself when trying to understand the difference between acrylic and cast acrylic.
Both materials are popular for their durability, clarity, and versatility. However, there are distinct differences between the two that can influence their performance and application. This article aims to shed light on these differences.
Acrylic: The Basics
Acrylic, technically known as polymethyl methacrylate (PMMA), is a transparent thermoplastic often used as a lightweight or shatter-resistant alternative to glass. Acrylic sheets can be coloured, tinted, mirrored or made opaque, providing versatility in applications.
The material is known for its outstanding weatherability, clarity and optical properties. Because of these features, acrylic finds its use in a myriad of applications, including signage, displays, aquariums, skylights, and even medical devices.
How Is Acrylic Produced?
The creation of acrylic involves the polymerisation of methyl methacrylate (MMA) monomer. This is achieved through a process called bulk polymerisation, which can be initiated using heat, light or other chemical catalysts.
Cast Acrylic: A Specialised Method
Cast acrylic is a particular type of acrylic produced by casting the polymer between two layers of high-quality glass. The process offers the advantage of producing sheets with consistent thickness and superior optical properties.
Differences Between Acrylic and Cast Acrylic
1. Manufacturing Process:
- Extruded Acrylic: Commonly referred to simply as ‘acrylic’, this material is produced by continuously pushing acrylic mass through a form to yield an acrylic sheet. The extrusion process can result in variations in sheet thickness.
- Cast Acrylic: This type is manufactured by casting the acrylic mass in moulds, typically between two sheets of glass. This method allows for greater flexibility in sheet thickness and overall uniformity.
2. Physical Properties:
- Extruded Acrylic: Generally has a lower molecular weight, which means it’s easier to cut and work with. However, it can be less chemically resistant and more prone to scratching.
- Cast Acrylic: Boasts a higher molecular weight, making it more robust and resistant to chemicals. It is also more resistant to scratching and can be polished to restore its original clarity if scratched.
- Extruded Acrylic: Tends to be more cost-effective due to its simpler manufacturing process.
- Cast Acrylic: Is typically more expensive because of its labour-intensive casting process and superior qualities.
- Extruded Acrylic: Ideal for high-volume projects that don’t require the highest optical clarity, such as simple glazing or protective screens.
- Cast Acrylic: Preferred for projects demanding precision, high optical clarity and aesthetics, like high-quality signage, retail displays, and intricate designs.
5. Thermal Properties:
- Extruded Acrylic: Exhibits a lower melting point, making it more sensitive to heat and less suitable for certain fabrications or environments where high temperatures might be encountered.
- Cast Acrylic: Can withstand higher temperatures without deformation and is, therefore, more suitable for certain fabrications, such as thermoforming.
Which One To Choose?
The choice between acrylic and cast acrylic largely depends on the specific needs of a project. For applications that require precision, superior clarity, and durability, cast acrylic is the obvious choice. However, for projects where these factors are less critical, and the cost is a significant consideration, extruded acrylic can be an apt choice.
For those unsure about which type of acrylic to use for a particular application, seeking advice from manufacturers or suppliers is wise. They can provide guidance on the most suitable material based on the project’s requirements.
For more info on this topic, it might also be helpful to consult industry publications and forums dedicated to acrylic and its applications.
Understanding the difference between acrylic and cast acrylic is essential for making informed decisions in various applications, from architecture to design. By recognising the unique properties of each, individuals and businesses can ensure they select the right material for their specific needs.