revitalizing 40 year old plastic lenses

[Tmoose]

I've several plastic tail light lenses that used to be nearly unbreakable that are now down right brittle. Is there something I could soak them in to restore some of the resilience?

I figure I better ask before soaking them in a Tupperware container filled with Oil of Olay or neatsfoot oil.

thanks,

Dan T

 

[Compositepro]

Some plastics, like PVC, contain plasticizers to soften them. Plasticizers are oily, high boiling, solvents that swell the plastic and make it rubbery rather than stiff. PVC pipe has no plasticizers while PVC upholstery in a car does. Plasticizers do slowly evaporate, so products like Armor All will restore the plasicizer. The plastic used in tail lights is probably polystyrene and it is getting brittle because the polymer is breaking down to lower molecular weight due to environmental oxidation (mainly due to sunlight). It cannot be restored.

 

[Demon3]

Compositepro is right. Despite what the environmentalists are telling everyone, plastics readily break down.

Chris DeArmitt PhD FRSC
President

Plastic materials consultant to the Fortune 100
Creating New Materials - Problem Solving - Innovation Keynotes - Expert Witness

http://www.phantomplastics.com

 

[Pud]

Here in he UK, tail light lenses were traditionally made from PMMA, which has excellent UV resistance as it is transparent to UV. Sounds like yours were possibly polycarbonate.

www.tynevalleyplastics.co.uk

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[3DDave]

I think the problem is cutting of cross-links. Better start looking for new-old stock or reading up on making molds.

From this:

http://read.nxtbook.com/wiley/plasticsengineering/january2015/consultantscorner.html

, if the plastic is not clouded then either UV driven chain scission or hydrolysis seem like they fit.