1.  PMMA (Polymeric Methyl Methacrylate) contains polar side-chain methyl, so it has hygroscopicity in some degree.  Its water absorption is about 0.3%-0.4%, thus, before forming, the PMMA should be dry for 4-5 hours under 80℃-85℃. 

2.  During the forming processing temperature range, PMMA has apparent non-Newtonian fluid property: the melt viscosity  will be decreased obviously with the increase of shear rate, and be sensitive facing with the temperature change. Therefore, when processing PMMA, improving the forming pressure and temperature can significantly reduce the melt viscosity for better fluidity.