Acrylic (Perspex) or Polycarbonate (Makrolon)?
Discussion
Which is the most resistant to scratching? Until yesterday Id have said 'polycarbonate; obviously!'; now Im not so sure. I visited The Deep in Hull, which for those unfamiliar is a very large fishtank, full of sharks. The water retaining walls and submerged windows were all made from 6" acrylic (Perspex) material and they were remarkably scratch free and retained quite impressive clarity. The hatch on my 944 track car, on the other hand, is made from polycarbonate (Makrolon), is as scratched as a b*stard and never manages to be much more than opaque, no matter how much I polish it.
Im familiar with the mechanical properties of both materials, but Im now wondering whether to replace the side windows with acrylic when the current polycarbonate becomes too marked: because it appears to be more resistant to scratching. Any thoughts?
Im familiar with the mechanical properties of both materials, but Im now wondering whether to replace the side windows with acrylic when the current polycarbonate becomes too marked: because it appears to be more resistant to scratching. Any thoughts?
Edited by GC8 on Tuesday 14th September 16:54
Uhura_Fighter said:
JD said:
Perspex is far too brittle for use as a car window, it will break and shatter and form nice dagger shaped pieces when you crash
refresh your polycarb, if you buy it from ebay, its as cheap as anything anyway!
refresh your polycarb, if you buy it from ebay, its as cheap as anything anyway!
That is nonsense, perspex can be made bullet proof.
Gizmo! said:
The rear screen in a car gets torsion forces going through it; over time I'd expect that to lead to 'crazing' at a very tiny level, which shows as cloudiness. Whereas the Perspex in the sealife centre is just resisting constant force.
You think the water in the tank is static? The tanks at the London Aquarium have sharks in them. I bet they cause some waves.Uhura_Fighter said:
JD said:
Perspex is far too brittle for use as a car window, it will break and shatter and form nice dagger shaped pieces when you crash
refresh your polycarb, if you buy it from ebay, its as cheap as anything anyway!
refresh your polycarb, if you buy it from ebay, its as cheap as anything anyway!
That is nonsense, perspex can be made bullet proof.
Normal glass can be laminated but it is no different to standard glass. The laminate layers make it tougher but it will still shatter into dangerous shards but the laminate interlayers hold it together. Bulletproof is usually between 5 and 30 layers of glass and laminate layers.
i have worked with all 3 products, macrolon is just another polycarb, which will scratch quite easily (even when cleaning with a soft cloth it will leave fine marks) though bash it with a hammer and it wont shatter like acrylic.
acrylic will stand up to scratching much better
acrylic will stand up to scratching much better
Edited by Viper on Friday 24th April 20:22
The part in question was Marguard... Im still tempted by acrylic sheet. Im aware of its physical properties (apart from scratch resistance / surface hardness evidently) and I feel that acrylics 'dangerous' propensity to shatter is exaggerated as its repeated. Its not too long ago that Perspex was commonly used for windows where it was regarded as being far safer and more durable than toughened glass...
I may line the 'glass' to calm the nerves of those who feel that itll turn into lethal daggers as soon as I have an 'event'. If the film will be durable on the outside then I may stay with PC.
I may line the 'glass' to calm the nerves of those who feel that itll turn into lethal daggers as soon as I have an 'event'. If the film will be durable on the outside then I may stay with PC.
Interesting topic
First of all you have to understand that Baths, aircraft canopies, viewing windows for aquariums and sheets of acrylic are all made from a different type of acrylic, baths are a sanitary grade of acrylic, often stretched formed then vacuum formed which changes its properties, Aircraft canopies, those made from acrylic (Perspex, Plexiglass, lucite) are made from a very very high grade of acrylic again stretched formed, Aquarium windows , thick ones are a specially made type of optically clear cast acrylic and a good old sheet of perspex is what everyone knows , can be used for all sorts and in the 60s , teams like BMC used perspex in place of glass because polycarb was not used back then..
As far as cars go in these days of safety comes first, polycarbonate has replaced perspex because perspex can sometimes shatter into dangerous pieces and this is not really what you need in a car accident (it is a lot stronger than glass though), theres two types of polycarbonate mainly used a standard grade (makrolon, Lexan, Arla) and a hard coated grade such as Lexan MARGARD, Makrolon AR, Arla Saphir as well as some cheapy stuffmade for bus shelters)
Std polycarbonate scratches pretty easy but you can look after it with the correct types of polish, the hardcoated versions resist scratches and have a harder surface than acrylic does - each type of material suits a specific job so you cant say one is better than the other, for race car windows a coated polycarbonate is the best.
Making plastic bullet proof is a tricky art, usally built from layers of glass, pvb, polycarb, pvb, polycarb,pvb, glass and so on, the amount of layers defining its class of resistance.
You can also manufacture glass / poly or poly / poly laminates for front windscreens or security glass
I own a company that manufactures polycarbonate windows for motorsport, marine, Aerospace and security applications,We have also done development work for Lexan and I have 20 + years as an acrylic fabricator so ive made all the stuff talked about here - PS never believe a sales rep from a plastics company, i have never yet met one that knows what he is talking about.
Happy to answer any other questions - Ive got a few youtube links as well so you can see how stuff is stretched and formed etc..
First of all you have to understand that Baths, aircraft canopies, viewing windows for aquariums and sheets of acrylic are all made from a different type of acrylic, baths are a sanitary grade of acrylic, often stretched formed then vacuum formed which changes its properties, Aircraft canopies, those made from acrylic (Perspex, Plexiglass, lucite) are made from a very very high grade of acrylic again stretched formed, Aquarium windows , thick ones are a specially made type of optically clear cast acrylic and a good old sheet of perspex is what everyone knows , can be used for all sorts and in the 60s , teams like BMC used perspex in place of glass because polycarb was not used back then..
As far as cars go in these days of safety comes first, polycarbonate has replaced perspex because perspex can sometimes shatter into dangerous pieces and this is not really what you need in a car accident (it is a lot stronger than glass though), theres two types of polycarbonate mainly used a standard grade (makrolon, Lexan, Arla) and a hard coated grade such as Lexan MARGARD, Makrolon AR, Arla Saphir as well as some cheapy stuffmade for bus shelters)
Std polycarbonate scratches pretty easy but you can look after it with the correct types of polish, the hardcoated versions resist scratches and have a harder surface than acrylic does - each type of material suits a specific job so you cant say one is better than the other, for race car windows a coated polycarbonate is the best.
Making plastic bullet proof is a tricky art, usally built from layers of glass, pvb, polycarb, pvb, polycarb,pvb, glass and so on, the amount of layers defining its class of resistance.
You can also manufacture glass / poly or poly / poly laminates for front windscreens or security glass
I own a company that manufactures polycarbonate windows for motorsport, marine, Aerospace and security applications,We have also done development work for Lexan and I have 20 + years as an acrylic fabricator so ive made all the stuff talked about here - PS never believe a sales rep from a plastics company, i have never yet met one that knows what he is talking about.
Happy to answer any other questions - Ive got a few youtube links as well so you can see how stuff is stretched and formed etc..
There is a feature of polycarbonate that acrylic shares only to a limited degree and that is notch sensitivity. This phenomenon can be seen in the material that very 'crackly' bags that some snacks come in: Bombay Mix and Japanese rice crackers for example. You find that they're difficult to start a tear to open them but once a tear is established it's very hard to stop it propagating all the way down the bag. That is notch sensitivity and compare it with a normal polyethylene film and you'll get the idea.
When PC is smooth its impact resistance is legendary, but scratch it to any degree or cut it to a vee shaped indent and the notch at the root of the scratch or root of the cut-out will concentrate the stress to the point that a previously almost unbreakable moulding or sheet will become very brittle in that local area. Radiusing any shapes helps a lot, and polishing out scratches will help too. Beware though, because whilst acrylic is quite easily attacked by organic solvents, polycarbonate is even more susceptible and even the fumes of a solvent can cause crazing of a stressed polycarb moulding. Finally, pure polycarbonate has quite poor ultraviolet resistance and has to be compounded with uv stabilisers but acrylic is extremely uv resistant naturally. Use the correct grade of PC and don't notch it or let solvents get near it and it's probably the better material for your purpose.
When PC is smooth its impact resistance is legendary, but scratch it to any degree or cut it to a vee shaped indent and the notch at the root of the scratch or root of the cut-out will concentrate the stress to the point that a previously almost unbreakable moulding or sheet will become very brittle in that local area. Radiusing any shapes helps a lot, and polishing out scratches will help too. Beware though, because whilst acrylic is quite easily attacked by organic solvents, polycarbonate is even more susceptible and even the fumes of a solvent can cause crazing of a stressed polycarb moulding. Finally, pure polycarbonate has quite poor ultraviolet resistance and has to be compounded with uv stabilisers but acrylic is extremely uv resistant naturally. Use the correct grade of PC and don't notch it or let solvents get near it and it's probably the better material for your purpose.
Interesting stuff. What would you use to make an aeroscreen for a Caterham or similar car? I have a smoked aero which I believe is perspex but would like a clear one made. Does anyone know anybody who could make one for me (preferably not too far from Slough) using the one I have as a template? What sort of price should I expect to pay?
Id make a pattern and make it out of 4mm polycarbonate. When it scratches (and it will, even if you stump up for Margard - which I mentioned in an earlier post), then you can cut and finish a replacement. Expect to pay about £30-£40 a square metre for the material and even one square metre will make several parts.
The above posts make interesting reading, but the thought of a front screen made from PC makes me shudder... Do you have any pictures?
The above posts make interesting reading, but the thought of a front screen made from PC makes me shudder... Do you have any pictures?
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