Neoprene Shrinkage 1

[Baheej]

I'm using a commercial quality adhesive backed neoprene rubber sheet to make sealing gaskets for an access panel. A week after assembling everything together, our QA noticed that the gasket had shrunk in size and that the corners of the access panel are no more sealed. The screw holes that were punched out in the gasket do not match with those in the access panel anymore (on an edge of 40” long, holes moved by as much as 31/16”). The supplier says that it is common for the rubber sheet to have some shrinkage (some of that due to shrinkage in the adhesive itself) but it shouldn't be that noticeable. Is this really common? Or did we stretch the gasket while applying it without knowing it? Are there are any readily available alternative? Suggestions? Regards.

 

[Baheej]

Correction: ..... panel anymore (on an edge of 40” long, holes moved by as much as 3/16”). The supplier says ....

 

[JIM317]

Place the sheet on a flat surface and make bench marks one meter apart on it. After 24 hrs check to see if their is shrinkage.,,If not you are stretching the adhesive coated sheet during application. Simplest solution would be to cut the holes 40 3/16" before fastening to panel to compensate for stretch

 

[corrosionman]

Baheej. Is your neoprene sheet very recently nanufactured. I vulcanise rubber sheets in a steam heate autoclave. If the Neo is not restrained it can shrink 10 % while curing. You must do simple tests to see what is going wrong. Regards CM

 

[JIM317]

I don't know of any compound that wont shrink after curing. In the case of sheet it should aged for the number of hours required to reach equilibrium, then proceed with the process
JIM KELLY

 

[Baheej]

Gentlemen, thanks for your responses. I did a test as JIM317 suggested and it turned out that the material shrinkage was negligible. It seems that the material was stretched when applied and that caused the apparent shrinkage.