Today's KNOWLEDGE Share : Acrylic (PMMA) vs. Polycarbonate (PC) :

Today's KNOWLEDGE Share 

Acrylic (PMMA) vs. Polycarbonate (PC) :

Acrylic offers greater tensile strength than polycarbonate, typically around 80 MPa, compared to polycarbonate at 60-70 MPa. That means it can stretch a bit more before breaking.

Similarly, acrylic wins the battle for flexural strength at 115 MPa vs. 90 MPa for polycarbonate, set a heavy object on unsupported sheets of each and PC will give way first (but not by much).

Both polymers are quite impact resistant, but where acrylic comes in around 17 times that of glass, polycarbonate boasts a whopping 250x increase.

However, polycarbonate is more prone to scratching than acrylic, but as many eyeglass wearers know, coatings are available to avoid this common problem.

There's little difference in transparency between acrylic and polycarbonate (92% light transmission for acrylic vs. 88% for PC). Glass straddles the two at 90% transparency.

Leave these two polymers outside for a few years, however, and you’ll have no problem determining which is polycarbonate, since it will have taken on a yellowish hue; acrylic is much more resistant to sun and UV-light. That said, stabilizers are available for its UV-challenged issues.

Put those same plastic parts in a hot oven and just the opposite will occur. Where acrylic has a maximum service temperature of 100 °C (212 °F), polycarbonate is good to 150 °C (300 °F).

Fire is a different matter. Polycarbonate has low flammability and tends to self-extinguish while acrylic burns slowly and releases carbon monoxide, so it is not recommended where flames may be present.

Chemical resistance is another important attribute. Polycarbonate is generally the winner here since it better withstands acids and alkalis and can be cleaned with ammonia-based products. Not so with acrylic. Both polymers, however, fare poorly around solvents (which are often used to join machined acrylic and polycarbonate parts)

source:www.protolabs.com