Polyurethane foams from oligomers derived from waste tire crumbs and polycaprolactone diols

Abstract

ABSTRACTThis work was an initial study on the synthesis of polyurethane foams (PUF) by using diols obtained from the controlled degradation of waste tire crumbs and from polycaprolactone (PCL) followed by examination of their biodegradability. Natural rubber (NR, cis−1,4 polyisoprene) and butadiene rubber (BR) chains contained in waste tire crumbs were chemically modified into carbonyl telechelic (CTWT) and successively into hydroxyl telechelic oligomers (HTWT). Four types of PUF were prepared with different molar ratios between the HTWT and the PCL diols. CTWT and HTWT were analyzed by 1H‐NMR, SEC, and FT‐IR to confirm their chemical structure. Formation of the urethane bond was demonstrated by FT‐IR spectra. The addition of the PCL diol increased the thermal degradation temperature of the PUF based on thermogravimetric analysis. According to scanning electron microscopy, polyhedral closed cells were obtained. The molar ratio of HTWT/PCL diols strongly affected the kinetic rate of foam formation and foam morphology. A low kinetic rate provided PUF with a high density, small cell size, and a broad cell size distribution. In order to assess biodegradation of PUF, the modified Sturm test was carried out for 60 days at ambient temperature (27–30 °C). The biodegradation of PUF containing only HTWT was 31.2% and 51.3% at 28 days and 60 days of testing, respectively whereas the PUF containing 1/0.5 HTWT/PCL diols (by mole) showed a higher biodegradation: 39.1% and 64.3% at 28 days and 60 days of testing respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44251.