what happen to PVC materials when plasticiser migrate?,

A common problem with Polyvinyl chloride (PVC) is that plasticisers tend to migrate during use. When the plasticisers migrate the material gets stiffer, this can for example cause cracks in the PVC material. Some PVC tends to crack more easily than other; finding out what is causing this problem would bring answers to a number of questions.

We have done a study, with variable results have been executed trying to solve the problem with cracks. We wanted to design a new test method to see if we were able to provoke cracks. If we were able to provoke these cracks, we could see when and why cracks appear in the current PVC item.

During our work, we evaluated two different PVC coated materials; PVC foam type and PVC compact. Both materials had two different structures - with foam backing and without foam backing. We performed mechanical, thermal and chemical treatments on the materials and with help from those experiment we were able to provoke cracks in one of our PVC coated materials.

According to our results, PVC foam type shows a higher tendency to crack in comparison with PVC compact, which only developed wrinkles. In PVC foam type, we could see cracks in an early stage during our mechanical testing. We evaluated our result by using a microscope and we observed a pattern in the tendency to develop cracks. PVC with foam backing had a higher tendency to crack in comparison with PVC without foam. Materials that have been abraded before flexing also tend to crack more easily.

In order to see if the plasticisers migrated into the foam during our experimental work we performed an extraction of PVC foam type, according to the results the plasticisers might have migrated to the foam.

The major conclusion from this study of PVC foam type and PVC compact is that PVC foam type tends to crack more easily than PVC compact. The foam seems to have a negative effect on the PVC. The abrasion before ageing also have a negative effect on the PVC coated material. We could not see that the chemicals affected the materials.

One of the main purposes with this study was to find a new test method for PVC coated items. We think that our test method with the ageing of the material in combination with the mechanical tests as Martindale and Ballyflex is a suitable test method while testing PVC coated materials.