Highly functional biobased polyols based on lactic acid ring-opened epoxidized soybean oil applied to rigid polyurethane foams

LEONEL MATÍAS CHIACCHIARELLI; RODRIGO HERRÁN; JAVIER IGNACIO AMALVY

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Año: 2019

0021-8995

Polyols with high hydroxyl functionality (FOH), between 9.0-12.6, where synthesized andcharacterized with DSC, TGA and SEC after studying parametrically the ring opening reaction(ROR) of epoxidized soybean oil (ESO) with lactic acid (LA) as a function of reactiontemperature and LA equivalent fraction (fLA). An increase of only 20°C in reaction temperature(from 80°C to 100°C) caused a change of hydroxyl number (+17.8%), hydroxyl functionality(FOH, -25%), viscosity (-14.0%) as well as oligomeric content (-24.1%). The fLA affected mostlythe ring opening yield (ROY) and only for fLA values above 0.4 it was possible to achieve valueshigher than 80%. Thermal transitions of the soybean-polyols (DSC) demonstrated a lesscompact structure with less pronounced transitions centered at higher temperatures. RPUFswere synthesized and characterized with SEM, DMA as well as compressive mechanical tests. RPUFs with very high specific compressive strength (7.8 kPa.kg-1.m3) were attained using solelythe biobased soybean oil. DMA analysis revealed a compromise relationship between thespecific compressive strength and its temperature dependence. To increase the first one, themost relevant aspect was to increase the FOH. Instead, to increase the latter one, the OH# hadto be maximized.