Window panes of aeroplanes are normally made of

ANS:A - perspex (PMMA)

Perspex, also known as polymethyl methacrylate (PMMA), is a transparent thermoplastic material commonly used in a variety of applications due to its optical clarity, lightweight nature, and impact resistance. Here's an explanation of Perspex (PMMA):

1. Chemical Composition: PMMA is a synthetic polymer made from the polymerization of methyl methacrylate monomer molecules. It consists of long chains of repeating methyl methacrylate units.
2. Optical Clarity: Perspex is known for its excellent optical properties, offering high transparency and clarity comparable to glass. It allows for the transmission of light without significant distortion or coloration, making it suitable for applications where visibility is important, such as windows, lenses, and displays.
3. Lightweight: PMMA is much lighter than glass, which makes it advantageous for applications where weight is a concern, such as in aircraft windows and automotive glazing. Its lightweight nature contributes to fuel efficiency and improved performance in transportation applications.
4. Impact Resistance: Despite being lightweight, Perspex exhibits high impact resistance, making it more durable and less prone to shattering than glass. This property is particularly important in safety-critical applications such as aircraft windows, where the material must withstand the forces exerted during flight and potential impacts from debris.
5. Weather Resistance: PMMA is resistant to weathering, UV radiation, and chemicals, which enhances its longevity and suitability for outdoor applications. It maintains its optical clarity and mechanical properties over time, even when exposed to harsh environmental conditions.
6. Ease of Fabrication: Perspex can be easily molded, machined, and thermoformed into various shapes and sizes, allowing for versatile design options and customization. It can also be bonded, welded, or glued using compatible adhesives, facilitating assembly and installation processes.

Due to these favorable properties, Perspex (PMMA) is widely used in diverse applications, including aircraft windows, signage, lighting fixtures, aquariums, medical devices, and consumer electronics, among others. Its combination of optical clarity, lightweight construction, and impact resistance makes it a popular choice for applications where performance and aesthetics are paramount.