What type of plastic used in laptop casings?
Thanks 
I searched on this topic a while ago and found then:
“the most common plastics used in collected PCs were: Acrylonitrile Butadiene Styrene (57%), Polyphenylene Oxide (36%), High-Impact Polystyrene (5%), and Polycarbonate/Acrylonitrile Butadiene Styrene Blend (2%).6 PVC plastic is not present in PCs in significant amounts.”
I do not know if the same goes for laptops but it might give you some indication on what is used.
If you are looking for information, check out the industry application section at GE Plastics website. A lot of companies work with them to design casings and custom materials/colors. Here is a small search result from their website:
Application: Electronics
Materials: LNP Thermocomp* Compounds, Lexan* Resin, Geloy* Resin, LNP Starflam* Compounds, Noryl* Resin, LNP Faradex* Compounds.
How bout titanium? juz read bout titanium and they also use it in laptops. im not sure though. is it good too? or too expensive? thanks.
ABS is a good bet for most consumer appliances. Nearly all x86 laptops (windows-based) are ABS or a similar styrene compound. Apple laptops are made of either a light metal (aluminum, magnesium or titanium in various alloys), or polycarbonate (Lexan, Makrolon).
Titanium is way too expensive to make an entire case out of, except in the highest-end computers. The metal is expensive, but not unreasonably so; the problem is working with it. I understand it’s basically impossible to cast (plus you wouldn’t want to waste that much titanium), and it eats up tools like crazy. It also has the tendency to react explosively with some cleaning (chlorine-containing) compounds. Add that to the fact that it’s brittle as hell, and large sheets will shatter if dropped…
FWIW, the titanium G4 Powerbooks weren’t actually titanium all through. I believe they were a plastic or light metal (alu/mag alloy most likely) frame with thin sheets of titanium cladding on the ouside, about 1/64" thick.