Polycarbonate (PC) is a versatile and durable thermoplastic polymer known for its unique balance of strength, transparency, and heat resistance. Its ability to maintain structural integrity while remaining lightweight makes it a popular material across many industries, from automotive components to consumer electronics. However, the material’s overall durability is complex and application-dependent, resting on a trade-off between its extraordinary strength against blunt force and its distinct vulnerabilities to surface damage and environmental exposure.
Resistance to Physical Force
The primary feature of polycarbonate’s durability is its outstanding resistance to impact, which sets it apart from traditional materials like glass and acrylic. Polycarbonate is often described as virtually unbreakable, possessing an impact strength up to 250 times greater than standard glass. This remarkable toughness stems from its amorphous molecular structure, which allows the material to absorb and dissipate energy across its polymer chains instead of propagating a crack.
When struck, the material exhibits high ductility and flexibility, meaning it tends to bend and deform rather than shatter. This characteristic makes it the material of choice for safety-critical applications, such as protective eyewear, riot shields, and machine guards. The ability to withstand sudden, high-rate loading conditions is formally measured through standardized procedures like the Notched Izod Impact Test.
This testing method quantifies the energy absorbed when a notched specimen is fractured by a swinging pendulum, providing a measure of the material’s toughness. Thinner sections typically yield in a ductile manner, demonstrating resistance to catastrophic failure. The inherent strength and shatterproof nature of polycarbonate make it a champion for applications requiring maximum physical resilience.
Vulnerability to Surface Damage
Despite its incredible impact strength, polycarbonate has significant limitations regarding its surface hardness and chemical resistance. The material has a comparatively low surface hardness, making it highly susceptible to abrasion, scratching, and marring compared to glass or acrylic. Even light contact with debris or cleaning equipment can easily compromise the surface integrity, leading to a reduction in optical clarity.
The material’s transparency can be diminished by surface imperfections that scatter light, which is why hard coatings are often applied to improve scratch resistance in high-traffic applications. Polycarbonate is chemically sensitive and can be readily attacked by a variety of common substances. Exposure to strong solvents, such as acetone, or certain household cleaners containing ammonia can cause the material to degrade, resulting in haze, cracking, or crazing.
This chemical vulnerability is particularly pronounced in areas of high stress or sharp corners within a molded part, where the combined effect of chemical exposure and material stress accelerates failure. Careful selection of cleaning agents and the use of protective surface treatments are necessary to maintain the material’s appearance and performance.
Long-Term Environmental Stability
Polycarbonate’s long-term durability is heavily influenced by its reaction to environmental factors, especially ultraviolet (UV) radiation. Unstabilized polycarbonate is naturally susceptible to photodegradation when exposed to sunlight, which causes a breakdown of the polymer’s molecular structure. This process manifests visibly as yellowing and hazing, reducing light transmission, and can eventually lead to embrittlement and a loss of mechanical toughness.
To mitigate this deterioration, polycarbonate intended for outdoor use, such as glazing or automotive headlamps, is manufactured with UV stabilizers or protective surface films. These additives absorb the harmful UV light, converting the energy into harmless heat and shielding the underlying polymer matrix. Polycarbonate also demonstrates good thermal durability, maintaining its performance across a wide temperature range.
The material’s strength and dimensional stability are preserved in extremely cold environments. It has a high glass transition temperature, meaning it resists softening and deformation up to approximately 147°C. This inherent thermal resistance makes it suitable for applications that must endure both high heat and freezing conditions.