Today, there are many options for clear plastic sheet, and many people do not know the difference between the two main options: Perspex® cast acrylic sheet and polycarbonate sheet. Each sheet is made differently and with different materials, hence the difference in characteristics and price.
Acrylic sheet, which is also known as polymethyl methacrylate sheet (PMMA), is made from a derivative of natural gas and trades under the name Perspex® along with other brand names. Polycarbonate is sold under the trade names Lexan® and Makrolon® and is used in various applications. Polycarbonate is more expensive, with extremely high impact strength and good resistance to fire ignition being its primary benefits, hence its association with bullet-proofing, since it is the material used for armoured car windows, vandalism protection and making electronic instrument housings.
On the face of it, these two clear materials seem similar, but it is important to understand their difference for you to choose the best one for the project you are working on. Due to their specific characteristics, one may favour your needs while the other may not fully serve your purposes. Here are some qualitative differences between these two common materials:
Both these materials are half the weight of regular glass but are stronger than glass by far. Perspex® acrylic sheet can resist impacting 17 times more than glass whereas polycarbonate can manage to resist impact 250 times more than glass. Polycarbonate is more flexible than acrylic, but will bend more under load bearing application. Acrylic is more rigid and can crack under extreme impact.
Light and clarity
Continuous exposure of standard polycarbonate to sunlight will make it yellow though the sheets can be treated to give a UV-resistant product to minimise yellowing. UV resistant polycarbonate sheet has a typical product outdoor guarantee of up to 10 years whereas clear cast Perspex® acrylic sheet is guaranteed for 30 years outdoors.
Polycarbonate sheet has 89% transmission of light, compared to 92% for acrylic. Acrylic sheet has the advantage that it can be more easily polished to restore its clarity, whereas this is more difficult with polycarbonate.
Working temperature range
Perspex® cast acrylic sheet has a wide range of temperature within which it can be used with a working temperature range from -40to 190 degrees F. It can expand and contract with temperature changes but will not shrink permanently over time. Polycarbonate, on the other hand, can handle temperatures up to240 degrees F.
It is possible to cut both materials using conventional tools like routers and saws. Perspex® acrylic sheet is easier to cut than polycarbonate, which is known to resist the initial push of the saw when starting the cutting process. When you cut polycarbonate sheet with a laser, it becomes yellow, and this, therefore, is not fully recommended. On the other hand, clear Perspex® acrylic sheet gives a high gloss edge directly on laser cutting.
When you drill Perspex® acrylic near to its edge or with a drill bit not recommended for plastics, then there is a risk it will crack. Polycarbonate, on the other hand, when drilled with a standard drill, even near the edge, will not crack.
Polycarbonate offers a flexibility of use with machining where its impact resistance means it is less susceptible to breakage during machining than acrylic. Intricate machining of Perspex® cast acrylic sheet is also very common with many users producing complex designs.
When you want to polish the edges of acrylic for a smooth appearance, then you are in luck– flame or buff polishing of acrylic sheet easily gives a gloss polished edge. Polycarbonate does not allow for such easy polishing and will not give as clear an edge.
When working with Perspex® cast acrylic sheet, heat bending works well to give very tight product radii. Polycarbonate sheet can also be cold bent / cold forming without heating, but only to a shallower radius.
Acrylic gives a final cleaner joint than polycarbonate when you cement it with recommended glue.
Cleaning Perspex Sheet
Both materials are easy to clean using 100% cotton cloth or microfiber and simple soapy water. It is not recommended that either of these materials should be cleaned with an organic solvent, as this could cause damage.
Polycarbonate sheet scratches more easily than Perspex® cast acrylic sheet. Also, Perspex® cast acrylic sheet has much better chemical resistance than polycarbonate to a wide range of acids, alkalis, alcohols and hydrocarbon products (e.g. petrol).
Both products may be guaranteed for outdoor use, although care needs to be taken to ensure the right polycarbonate product is used.
Polycarbonate is typically two to three times more expensive than acrylic.
Color selection of Perspex Sheet
Polycarbonate sheets have limited color selection while perspex sheet is available in a wide variety of colours.
Therefore these two materials have different uses depending on their characteristics as listed above.
Perspex® cast acrylic sheet finds uses in areas where optimal weather and in-service resistance are required, since it can withstand weather, sunlight and general handling better than polycarbonate. It finds applications in areas such as corporate signage, ice hockey spectator protection, helicopter windows, motorcycle wind-deflectors, caravan glazing and automotive rear lights. Other specialist applications include large aquariums and swimming pool windows.
Polycarbonate, on the other hand, is very resistant to impact force and is not that easy to shatter, hence its use in anti-riot shields and visors, bulletproof glass when the layers are thick enough, DVDs, sunglasses, safety glasses, vehicle headlamps, off-road vehicle glazing, and drinking bottles, amongst other uses.