Impact of diverse diols and diisocyanates on thermosetting bio-based polyurethane films

Abstract

Polyurethanes (PUs) are highly versatile polymers utilized in a wide range of applications. However, conventional PUs typically depend on petroleum-derived polyols, which present notable environmental and health challenges. To mitigate these issues, bio-based polyols have been developed as sustainable substitutes. Among these, vegetable oil (VO) based polyols have garnered significant attention for their potential to diminish dependence on fossil fuels. Even though bio-based PUs are better for the environment, they nevertheless have problems with good mechanical strength. Improving the mechanical properties of bio-based PUs is the goal of this research. To do this, several diols with aliphatic and aromatic nature are used as cross-linkers, including 1,3 propanediol (PR),1,5-pentanediol (PN), and hydroquinone (HQ). The effects of different aromatic and aliphatic diisocyanates on the thermosetting PU production process are being investigated. By adjusting the cross-linkers and diisocyanates, the mechanical strength and stiffness of the PU films are anticipated to increase. Samples containing methylene diphenyl diisocyanate (MDI) exhibited a tensile strength of approximately 40 MPa, up from 6 MPa in the control samples when crosslinked with HQ (10 wt%). For hexamethylene diisocyanate (HDI) based PU films, the sample with the maximum tensile strength of 9 MPa was PR-15 wt% (H). Also, elongation was better in films containing HDI than in films having MDI. Further evaluation of the cross-linking and stiffness of these PU films was performed using thermal experiments, examination of gel content, and degree of swelling.