Stability of the HPC/PU polymeric blends in accelerated weathering and biological environments

: Polymeric blends of Hydroxypropyl cellulose (HPC) and Polyurethane (PU) 9 (PU/HPC_20/80; PU/HPC_50/50; PU/HPC_80/20) have been prepared by solvent (DMF) 10 casting method and investigated after exposure to accelerated ageing conditions by using a 11 mercury lamp (200 < λ < 700 nm), at 60% humidity and 40 o C for 600 h. Their hydrolytic 12 stability was evaluated after immersing them for 48 h in different pH (2.6 and 7.4) 13 Phosphate-Buffered Saline (PBS) media. The structural changes in the composition of blends 14 during the accelerated weathering and hydrolysis processes have been investigated by means 15 of FT-IR (Fourier Transform Infrared) spectroscopy and DSC (Differential Scanning 16 Calorimetry) analysis. FT-IR spectra of the blends after 600 h of irradiation and 48 h 17 hydrolysis in PBS solutions revealed a major degradation process especially in the HPC 18 component and in the soft segment of PU. The changes in the crystallinity of the blends have 19 been also evaluated by FT-IR (by determination of Total Crystallinity Index (TCI) and 20 Lateral Order Index (LOI)) and DSC that evidenced the reduction of the melting enthalpy 21 (( ∆ H m ) and of its corresponding crystallization ( Tc ) on heating/cooling runs indicated that 22 ageing strongly affects the crystallinity of the PU/HPC blends.