In order to obtain an unsaturated polyester (UP) suitable for the application of end users (i.e. such as flexible abrasives tapes, UV curable coatings and inks), the first aim of the action B3 is to define the right final viscosity of the biopolyester. So the fine-tuning of the UP viscosity had great importance for the subsequent action B5, B6 and B8. The viscosity measurements were determined in gardner scale and were strictly related to the molecular weight distribution measured by Gel Permeation Chromatography (GPC). The used monomers for the UP synthesis were IA and 1,2-propylen glycol (MPG) totally derived from renewable resources (see figure). The conversion degree of the monomer to polymer was measured by measuring the acid concentration residue and viscosity in the Gardner scale. After 3 h at 190°C the UP reached the expected final Gardner viscosity C with an average molecular weights (Mn) of 1.200Da (Daltons). This UP was diluted with DEI or DBI, but the final viscosity was too high to develop other technical actions. So, a second polymerization reaction were carried out in the same experimental conditions with a shorter reaction time providing a UP resin with lower Gardner viscosity A and Mn of 817Da showing at 25°C a viscosity of 170mPa.s. This viscosity of the diluted UP with other IA-based monomers, such as DBI and DEI, was studied for the subsequent technical actions (B5, B6 and B8).
The scale up of the UP synthesis in order to prepare the necessary amount to other project units were obtained with several batches of 50 Kg by using the experimental conditions adopted the final synthesis procedure. A synthesized UP sample (50kg) was diluted with 25% by wt DBI in order to prepare other technical actions.
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