Is UV curing a shrinking violet?

摘要

Polymerisation shrinkage is a common occurrence in radiation curing, especially for free radical polymerisation of (meth)acrylate-based formulations, and is often cited as the cause of performance problems. The shrinkage arises due to a reduction in volume during the polymerisation process. Before irradiation, the (meth)acrylate groups associate together at Van der Waals distances apart (about 4A), but after curing the (meth)acrylate groups are covalently bonded together through C—C bonds (about 1.9 A). This can lead to volume shrinkage of 20% or more. In general, methacrylates exhibit lower levels of shrinkage than acrylates.