aging plastic parts 1

[Bob456]

I need to run a test on a pump that has 4 hard plastic feet and two soft plastic motor supports. These two parts have the same dimensions, just different materials. The test is to see if the soft motor supports can be replaced with the harder material. The goal is to have fewer parts in stock.
The first step is to see if there is a difference in the noise between the two parts with new out of the box parts.
The second step is to rapidly age the material 3-5 years and to perform the noise test again comparing the two materials.
The only thing I know about the material is that the are listed as white pvc hard and white pvc flex. A black color is added at the mold. I assume that its some form of pvc.
I am trying to contact the vendor to find out excatly what it is as no one here knows.
Can anyone tell me how to age this material. I thought about cooking it in the oven but I don't know what temperature and how long.

 

[patprimmer]

Accelerated ageing is not a very exact science, and many unknowns can distort the results.

Heat is the obvious way to accelerate degradation. It accelerates oxidation, chain shortening and cross linking.

It can have an annealing effect and effect shrinkage, distortion and frozen in stress.

Heat will accelerate the rate at which rigid PVC goes brown, hard and brittle.

It will also increase the rate of plasticiser migration in flexible PVC.

If the part is subject to load, heat will be quite non linear in its effect on creep.

Heat will not accelerate the effects of fatigue when a part is subject to vibration.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
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[TheAnswerGuy]

BOB,

You can try contacting Northview Laboratories.
They do accelerated aging studies.

You can reach them at:

http://www.northviewlabs.com/

theanswerguy@tr-usa.com

 

[dwightdixon]

Flexible PVC changes with time and enviromental exposure. It can get harder due to plasticizer evaporation or extraction. The hardness also changes greatly with temperature so the sound dampening changes dramatically with the product use temperature. If the product is currently made from PVC and its performance is acceptable, the specification or expectation must be very broad. Have you tested a current product that is 5 years old for performance acceptability? If that is ok, then another PVC that is slightly harder that performs acceptable when new, will likely change the same amount as it ages as the current product that starts out with a higher amount of plastizier. If the current product just barely is acceptable after being around 5 years the new higher hardness product will most likely not be successful.