Plexiglass or acrylic glass remains one of the top substitutes for transparent glass. Just like glass, different manufacturers can use it to make windows, aquariums, and so much more.

However, it’s a bit surprising that car manufacturers never use it to make car windows as an alternative material to transparent glass. It begs the question; why is plexiglass not used for car windows?

The answer is that the material doesn’t meet automative requirements to ensure safety for the occupants of the vehicle and durability for the windows. 

An In-Depth Explanation of Why Plexiglass Is Not Used for Car Windows

1. Plexiglass Is Flammable

Unlike glass, plexiglass or acrylic glass is flammable. Due to fire safety concerns, it’s forbidden by automotive standards. Some accidents can result in a fire, and it’s due to this reason that car makers will try as much as they can to use inflammable materials with a high burn resistance. 

2. Acrylic Glass Will Scratch More Easily than Than Normal Glass

It’s no secret that most of the time people drive their cars with the windows rolled up. This is to ensure safety and comfort. The windows block all the external elements such as wind, debris, insects, leaves, and tree branches that could otherwise cause injury to the vehicle’s occupants or even an accident.

Unlike glass, Plexiglass has low scratch resistance. That means it would sustain some serious scratches over time by blocking the external elements each time the car is in motion.

Consequently, this can lead to reduced visibility for the driver and an increased risk of an accident. 

3. Acrylic Glass Pauses a Serious Collision Risk

Another reason why plexiglass is not used for car windows is that it poses a huge risk during a collision. After discovering that shattering glass causes more injury than anything else during a crash, have found a way to make car windows safer.

They design the glass especially that for the windshield to shatter into small blunt pieces as opposed to large sharp ones during a head-on collision.

Unfortunately, they have never been able to design acrylic glass in the same manner as automotive glass. 

4. Toxic Gases and Substances

Sometimes a car accident can result in an inferno that would easily burn down the car if not put out quickly enough. The situation can be worsened if the car’s windows are made of plexiglass instead of normal glass.

That’s because this material will release some toxic substances when burning. These include PMMA(Poly(methyl methacrylate) and MMA(Methyl methacrylate).

If the vehicle’s occupants inhale these substances, they can suffer from serious health complications that include high blood pressure, lung problems, and allergic reactions.

5. Plexiglass Fogs Over Time

Ever wonder why some cars have headlights that look somewhat fogged and pitted? You probably conclude that they are made from poor-quality materials, which is true. Some manufacturers will use acrylic glass as opposed to auto glass for their headlights. 

While this material serves as a good substitute for glass, it has certain qualities that make it unsuitable for automotive engineering. For example, it will fog over time.

Acrylic headlights will fog from UV light after a few years of usage. That can mean reduced visibility and an increased risk for accidents. 

What Kind of Plastics Can You Use for a Broken Car Window?

It’s not a good idea to use plastic to fix a broken car window. If your window is damaged, you take the car to the mechanic to fix the problem.

But as a temporary measure, you can tape it up with the right plastic, which has almost similar characteristics to glass. Thermoset plastics can be a great choice as these plastics are almost similar to glass. For example, they;

• Are transparent.
• Have a high burning resistance. 
• Shatter into fine blunt particles.
• Are chemically resistant. 
• Are scratch or abrasion resistant. 
• Are flexible and rigid. 

Top thermoset plastics for automotive windows include PUR (Polyurethane), PE (Polyethylene), PC (Polycarbonate), and ABS (Acrylonitrile-butadiene-styrene copolymer)

Is There Any Type of Plastic Windows that Can Replace a Car Window and Work?

Currently, no plastic material can entirely replace the glass as a material for car windows. Even though some plastics such as the above are promising, they don’t fully meet the standards set for the best window material in cars. The research is still ongoing and maybe scientists will discover something in the future. 

Conclusion

Even though plexiglass looks much like glass to the naked eye, car manufacturers will never use this material in making windows.

That’s because of a few characteristics it has that make it unsafe in automotive engineering. For example, it’s flammable, scratches easily, and shatters into large sharp pieces, unlike glass. Also, it releases toxic substances when burning and fogs over time as opposed to glass.