Polycarbonate is a high-performance, transparent material widely used in engineering and manufacturing. As a thermoplastic polymer, it can be repeatedly melted and reformed. Polycarbonate is accurately described as a hard and rigid material at room temperature, making it suitable for load-bearing applications.
Understanding Material Properties: Hardness vs. Toughness
Understanding polycarbonate’s nature requires differentiating between two distinct material characteristics: hardness and toughness. Hardness refers to a material’s resistance to scratching, indentation, or surface abrasion. Toughness, conversely, is the ability of a material to absorb energy and deform plastically without fracturing or breaking.
Polycarbonate exhibits moderately high hardness, contributing to its overall rigidity and stiffness. However, its surface hardness is relatively low, making it susceptible to scratching compared to materials like acrylic. The material’s defining characteristic is its outstanding toughness, which prevents it from shattering. This combination allows it to be rigid like a hard plastic but behave unlike a brittle material, such as glass.
The Remarkable Impact Resistance of Polycarbonate
Polycarbonate’s primary mechanical advantage is its exceptional impact strength, resulting directly from its inherent toughness. It is approximately 250 times more resistant to impact than standard glass and significantly stronger than clear plastics like acrylic. This ability stems from its molecular structure, which allows it to undergo large plastic deformations when struck, absorbing impact energy rather than failing catastrophically.
The material maintains its rigidity and shape due to its high glass transition temperature (Tg). For standard grades, this temperature is around 147 degrees C (297 degrees F), the point where the polymer transitions from a hard, glassy state to a softer one. Operating well below this point ensures the material retains its structural integrity and stiffness, maintaining its dimensions even when exposed to heat stress.
Where Polycarbonate’s Properties Shine (Applications)
Polycarbonate’s combination of rigidity and extreme toughness makes it an engineering material of choice for numerous applications. Its non-shattering characteristic is utilized in safety equipment, such as protective goggles, face shields, and helmet visors, where impact resistance is necessary for personal protection. Its strength and clarity also make it a common substitute for glass in architectural glazing and construction.
Polycarbonate is used for making compact discs (CDs) and digital versatile discs (DVDs) due to its optical clarity and dimensional stability. In the automotive industry, it is frequently used for headlamp lenses because it resists road debris without cracking. It is also laminated to create “bullet-resistant glass” for security applications, demonstrating its superior capability to withstand high-force impacts.