Abstract
In the previous paper, the physical anchoring principle was proposed to obtain scummingless SMC moldings. When the styrene (ST)-divinyl benzene (DVB) loosely cross linked polymer is applied for the low profile additive to SMC, it is desirable to use the additive polymers having particle size under 50μm to avoid the growth of waveness at the surface of the moldings. To spread the allowable range of particle size of the polymer, it was suggested by the authors that the glass transition temperature of the polymers must be low to near the room temperature. The main purpose of this paper is to confirm the supposition. The experiments were carried out on methyl acrylate (MA), MA-ST and MA-ST-DVB. As the results, it has been revealed that the supposition is quite right, MA monomer has a property to give the loosely cross linked polymer without any cross linking agent but a cross linking one, such as DVB, for MA-ST monomer system is an essential component to obtain the scummingless additive polymers and small addition of the DVB into MA-ST mixed monomer bears an important role to prevent the growth of two types of polymer with different Tg.
