This technical action was implemented to obtain Bulk Moulding Compound (BMC) formulation, with UP resins for replacing styrene monomer with DBI, synthesized by action B.1. The usual viscosity of UP used for BMC application is 1800-2000 mPas at 25°C. In order to prepare the UP resins, a specific synthesis of IA-based UP with the adapted viscosity was carried out in the action B3. For the BMC application mixtures, a further DEI were added up to 40% by wt to decrease the viscosity at room temperature. Unfortunately, the mixture reactivity with the DEI remained low, up to 10% by wt of a multifunctional acrylated monomer, such as trimethylolpropane-triacrylate (TMPTA), was added for increasing the crosslinking efficiency. The TMPTA addition in the thermo-curable mixture for BMC applications showed a curing time of 3’,43’’, which was very similar reactivity to that obtained when styrene monomer is used as reference material.
Finally, two reactive mixtures were prepared by using unsaturated biopolyester diluted with DBI, HPMA and TMPTA (35% by wt) for some prototype preparation. The effects on the thermo-mechanical properties in presence and absence of styrene for the same composition of the reactive diluents (DBI, DEI, TMPTA) and IA-based UP resin were studied for the following mixtures:
a) type A: UPR based on MPG and IA in Styrene; b)Type B: UPR based on MPG and IA dissolved in DBI, HPMA and TMPTA.
Two BMC mixtures for the BMC applications were prepared having the following compositions (% by wt):
i) unsaturated polyester (used as reference material with styrene) type A (21% by wt), Mineral filler (47% by wt) and chopped Glass fiber (19% by wt) and other additives (13% by wt).
ii) unsaturated polyester resin (without styrene) type B (24% by wt),Mineral filler (48% wt), chopped Glass fiber (20% by wt) and other additives (8% by wt)
BMC prototypes, having dimensions 220x200mm, were obtained by compression molded a 145°C for 120s applying a pressure of 200 Bar. The BMC prototype prepared by using the type A resin gave regular, good and homogeneous fully cured materials. The mechanical characterization tests according the quality control procedures for determining the linear shrinkage, flexural modulus and impact (Charpy-DIN16911).
The BMC produced using the type B resin without styrene showed poor mechanical properties, since the cured BMC materials seemed too soft for this application.