Test Methods for Shrinkage of Knitted Fabric
2016-10-10 09:07 | writer: admin
The structure feature of knitwear makes it difficult to control the rate of shrinkage. So at first, we need to understand the relaxed state or relaxation steady state of knitwear, which is the steady state of size after the disappearance of the internal stress of knitwear. They can be divided into four states:
1. Static dry relaxed state: put knitwear onto the flat floor under the unstressing condition, make it natural relaxed so that reach to the relaxed state within a limit time.
2. Static wet relaxed state: put the knitwear into the immersion liquid, dehydrated after some certain time, and lay down under the unstressing condition so that it can reach to the state of relaxation after drying .
3. Dynamic wet relaxed state: scroll washing the fabric and dehydrated it, make it lay down and dry under the unstressing condition, in the end reach to the relaxed state after a limit time.
4. Completely relaxed state: scroll washing the fabric and dehydrated it, then dry it in the scroll state, in the end reach to the relaxed state after a limit time.
In order to test kinds of relaxed state of knitwear, it is necessary to deal with the change of sample size in pre-post processing, so the difference of measure percentage is [ shrinkage ], and it also act as a indicator for fabric dimensional stability. The shrinkage of fabric can divide into positive value and negative value. If transverse shrink while longitudinal growth, shrinkage rate of transverse is positive value and longitudinal is negative value. The shrinkage of fabric is depended on the material of fabric, structure of fabric and methods of dyeing and finishing. For many factors, if we want steady, we must strictly concern and control every process from the beginning to the end.