Material Drying Issue

Material Drying Issue

A customer called in with issues with their final part. They were seeing silver streaking throughout the part and could not get rid of this problem. They dried the material overnight at 80°C using a desiccant drying system, but the silver streaking would not go away. The material being used was Santoprene™ brand TPV 101-87. I asked the customer how old the material was, and the customer said they have had a gaylord of material for about 7-8 years opened.

Since this resin was hydroscopic, I responded that the material may have bound moisture, which can not be removed when drying. This can happen when the material is left exposed to the elements for long periods of time or extreme humidity. Two solutions were given to the customer. The first solution would be to put vents on the screw or to process, regrind and reprocess the material. During the melt phase, the bound moisture will escape. This is what causes the silver streaking issue. The other solution was to purchase new material and ensure that it is stored at the recommended storage conditions so that the problem would not come back later.

Posted on 2008-04-17 2:10 PM