Tolonate Synthesis

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Tolonate® HDB 75 BX, derived from hexamethylene diisocyanate was purchased by Perstorp. Acaí berry polyol powder was kindly provided by the Laboratory of Eco-composites from the Federal University of Pará, Brazil. The extraction method was previously described28 . 2.2 Polyurethane preparation PU was prepared by a two-step procedure in a nitrogen atmosphere. In the first step, the synthesis was carried out in a batch reactor by a mixture of polyol and HDB at a heating rate of 10 oC/min to 75 oC/min by stirring at 100 rpm and 4 kgf/cm2 of pressure in order to form an NCO-terminated prepolymer. At 75 oC, a sample of prepolymer was taken out of the reactor and placed in a high density polyethylene bottle for cooling. In the second step, the resulting mixture in the reactor …show more content…

2.5.3 Thermal characterization The investigation of the thermal composition of the PU was carried out using TGA, model TGA-50 (Shimadzu Instruments Kyoto, Japan). A sample mass of about 8 mg was heated under a flowing nitrogen atmosphere (50 mL/min) from 30 to 600 oC, at a heating rate of 10 oC/min. 7 2.6.1 Cell culture Human normal lung fibroblasts (a model cell line, MRC-5) were obtained from ATCC (Manassas, VA, USA). Cells were cultured in Dulbecco’s Modified Eagle Medium (DMEM) with 10% fetal bovine serum (FBS, Gibco). Growth media contained 100 units/mL penicillin and 50 μg/mL streptomycin and cells were cultured in a 37 oC, humidified, 5% CO2/95% air environment. Cells were used at population numbers below 5. 2.6.2 In vitro cell viability assays To determine the toxicity of the polyurethane and the nanocomposite, cells were seeded onto 96-well culture plates at 0.5×105 cells/mL and were incubated for 24 hours. After that, cells were incubated with 100 μL of the aforementioned cell culture medium for 24 hours. The amount of formazan crystals formed was measured after 2 hours of exposure to the MTT solution in dimethyl

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