Polycarbonate and acrylic are transparent plastics often used as alternatives to traditional glass due to their lighter weight and increased strength. While they appear similar, these materials have fundamentally different chemical structures—polycarbonate is a thermoplastic polymer, and acrylic is polymethyl methacrylate (PMMA)—which results in distinct performance characteristics. Understanding these differences is crucial for selecting the right material, as one may excel in impact resistance while the other is superior in optical clarity. Both materials are less than half the weight of glass, but their suitability depends entirely on the required properties.
Fundamental Mechanical Properties
The most significant distinction between these two materials lies in their resistance to physical force. Polycarbonate possesses an impact resistance about 250 times greater than standard glass and approximately 30 to 40 times stronger than acrylic. This exceptional resilience means polycarbonate is virtually unbreakable, absorbing shocks and impacts without cracking or shattering, making it the preferred material for high-stress environments.
Polycarbonate is more flexible, enabling it to be cold-formed or bent into shape without heating. This elasticity ensures that the material absorbs energy rather than fracturing, which is why it is used in safety equipment like riot shields and machine guards. Acrylic, in contrast, is characterized by greater rigidity and stiffness, giving it a more glass-like feel.
While acrylic is significantly stronger than glass—up to 17 times more impact resistant—it is inherently more brittle than polycarbonate. High-impact forces can cause acrylic to crack or shatter, similar to glass, though it does not splinter into dangerous shards. This rigidity makes acrylic suitable where a firm, unyielding structure is necessary, but it limits its use in environments prone to heavy physical abuse.
Practical Use and Workability
Acrylic’s inherent rigidity makes it relatively easy to cut cleanly, often utilizing laser cutters to achieve sharp, polished edges. However, drilling acrylic requires specific techniques to prevent cracking, especially when holes are placed near the edges of a sheet.
Polycarbonate’s toughness makes it more challenging to machine precisely, as it tends to gum up or melt if processed too quickly. Conversely, polycarbonate is much easier to drill without the risk of cracking or splintering, and it can be cold-formed into complex curves.
Acrylic demonstrates superior resistance to scratching, maintaining its aesthetic appeal in display applications. Standard polycarbonate is a softer material and is highly prone to surface scratches, though this can be mitigated by purchasing versions with a specialized hard coating. Acrylic surfaces can also be easily polished to remove minor scratches and restore clarity, a process that is less effective for polycarbonate.
Chemical resistance dictates cleaning methods. Polycarbonate can be damaged by certain cleaning agents containing ammonia or harsh solvents. Acrylic has a lower chemical resistance overall and is best cleaned with mild soap and water or specialized plastic cleaners. While polycarbonate generally resists a broader range of chemicals like acids and gasoline, neither plastic should be exposed to harsh solvents.
Optical Characteristics and Thermal Resistance
Acrylic boasts superior optical clarity, often transmitting up to 92% of visible light, which is even higher than some glass types. This exceptional transparency makes acrylic the preferred choice for high-end displays, aquariums, and picture framing where maximum clarity is desired.
Polycarbonate transmits slightly less light, typically around 88%, and can sometimes possess a slight tint or haziness. In terms of long-term clarity outdoors, acrylic naturally resists UV radiation and maintains its transparency better over time without treatment. Polycarbonate naturally blocks UV rays, but it tends to yellow or degrade under prolonged sun exposure if it is not manufactured with a UV-stabilizing layer.
Polycarbonate has a distinct thermal advantage, with a higher heat deflection temperature that allows it to withstand continuous exposure to temperatures up to approximately 120°C (248°F). This stability prevents the material from softening or deforming in heat-exposed environments. Acrylic begins to soften at much lower temperatures, typically around 85°C (185°F), which limits its use in applications near heat sources or requiring fire-rated performance.
Cost, Longevity, and Ideal Applications
Acrylic is consistently the more economical choice, with prices often being 35% or more lower than polycarbonate. The higher cost of polycarbonate is primarily due to the specialized manufacturing process required to achieve its superior impact strength and thermal stability.
For longevity, the environment dictates the better material. Acrylic is often chosen for outdoor signage and architectural glazing because of its natural resistance to weathering and clarity retention. Polycarbonate’s durability makes it last longer in high-impact situations, while its inherent flexibility helps it withstand temperature fluctuations in colder environments without cracking.
Polycarbonate is the optimal material when safety and strength are paramount, such as in safety glazing, machine guards, and high-performance applications like motorcycle windshields. Acrylic is best utilized where visual appeal, high clarity, and cost-effectiveness are the main priorities, making it ideal for retail display cases, picture frames, and large-scale public aquariums. The final selection depends on whether the project requires the unmatched strength of polycarbonate or the superior optical quality and lower price of acrylic.