what is Acrylic plastic sheet (10 marks)

Do you mean acrylic glass or acrylic sheet?
Polymethyl methacrylate (PMMA) or poly (methyl 2-methylpropanoate) is the synthetic polymer of methyl methacrylate. This thermoplastic and transparent plastic is sold by the tradenames Plexiglas, Limacryl, R-Cast, Perspex, Plazcryl, Acrylex, Acrylite, Acrylplast, Altuglas, Polycast and Lucite and is commonly called acrylic glass or simply acrylic. The material was developed in 1928 in various laboratories and was brought to market in 1933 by Rohm and Haas Company.
The material is often used as an alternative to glass. Differences in the properties of the two materials include:
- PMMA is less dense; its density can range from 1150-1190 kg/m^3. This is less than half the density of glass which ranges 2400 to 2800 kg/m^3.
- PMMA has a higher impact strength than glass and does not shatter but instead breaks into large dull pieces.
- PMMA is softer and more easily scratched than glass. This can be overcome with scratch-resistant coatings.
- PMMA is typically processed at a lower temperature than glass, just 240-250 °C.
- PMMA transmits up to 93% of visible light (per metre). A simple comparison with glass is not possible as glass is not a substance with a single composition and is made with an extreme range of optical transmittances from 0% to practically 100% (at least 99.99% infrared in long distance optical fibers). Doped - PMMA can achieve transmittances of 91% to 98%, suitable for consumer fiber.
- Unlike glass, PMMA does not filter ultraviolet (UV) light. PMMA transmits UV light down to 300 nm. Some manufacturers add a coating to PMMA sheets to make them absorb UV light. PMMA molecules have great UV stability compared to polycarbonate.
- PMMA allows infrared light of up to 2800 nm wavelength to pass. IR of longer wavelengths, up to 25,000 nm, are essentially blocked. Special formulations of colored PMMA exist to allow specific IR wavelengths to pass while blocking visible light (for remote control or heat sensor applications, for example).
- PMMA can be joined using cyanoacrylate cement (so-called "Superglue"), or by using liquid di- or trichloromethane to dissolve the plastic at the joint which then fuses and sets, forming an almost invisible weld. PMMA can also be easily polished to restore cut edges to full transparency.
The refractive index of PMMA compounds usually ranges from 1.4893 to 1.4899 (a vacuum's is 1).
To produce 1 kg of PMMA, about 2 kg of petroleum is needed. In the presence of oxygen, PMMA ignites at 460° C and burns completely to form only carbon dioxide and water.
Related polymer poly(methyl acrylate)
The polymer of methyl acrylate, PMA or poly(methyl acrylate), is similar to poly(methyl methacrylate), except for the lack of methyl groups on the backbone carbon chain.[6] PMA is a soft white rubbery material that is softer than PMMA because its long polymer chains are thinner and smoother and can more easily slide past each other.

Uses
PMMA or Acrylic is a versatile material and has been used in a wide range of fields and applications.
- resistant substitute for glass
PMMA Acrylic glass is commonly used for constructing residential and commercial aquariums.
PMMA is used in the lenses of exterior lights of automobiles. [7]
The spectator protection in ice hockey stadiums is made of PMMA.
Motorcycle helmet visors
Police vehicles for riot control often have the regular glass replaced with acrylic to protect the occupants from thrown objects.
Acrylic is used for viewing ports and even complete hulls of submersibles, such as the Alicia submarine's viewing spheres and the Bathyscaphe Trieste's windows.
Polycast acrylic sheet is the most widely used material in aircraft transparencies (windows). In applications where the aircraft is pressurized, stretched acrylic is used.
I hope this can help your understanding. =)

Acrylic plastic sheet is sheet of plastic made of acrylic or sheet made of acrylic plastic.