Study On Preparation And Properties Of Millable Polyurethane Elastomer With Halloysite Nanotube Composites

MDI-based and TDI-based millable polyurethane (MPU)/halloysite nanotubes (HNTs) nanocomposites with high tensile strength, elongation at break and Young's modulus were prepared by solvent-free prepolymer and one-step method, respectively. In the synthetic linear MDI-based polyurethane elastomer nanocomposites, with only 1 wt% of HNTs incorporated, an 1.17-fold increase in tensile strength and 0.58-fold increase in elongation at break were achieved, respectively. Spectacularly, remarkable improvement of Young's modulus were obtained after curing using crosslinking agent including toluene diisocyanate dimer and DCP. Efforts have been made during the past few decades to replace expensive polyols with low cost natural vegetable oils or other derivatives in the production of urethane products. Among the vegetable oils, castor oil (CO) possessing hydroxyl groups appears to be a good polyol for the synthesis of urethane elastomers. In the synthetic linear TDI-based polyurethane elastomer nanocomposites, CO were used as a renewable resource polyol. With only 0.5 wt% of HNTs incorporated, an 0.35-fold increase in tensile strength and 0.63-fold increase in Young's modulus were achieved, respectively. The sharp decline in the tensile strength of the nanocomposites after adding 5 wt% HNTs was shown, which may due to agglomeration occuring in the polyurethane matrix with higher content of HNTs resulting in greatly declining the degree of hydrogen bonding between the hard segments, and thus to affect its mechanical performance.In this paper, inexpensive HNTs owing high strength, high modulus and other characteristics were used as materials for compounding nanocomposites. Moreover, benzene, toluene, N, N'-dimethyl acetamide, ethyl acetate and other harmful solvents were unused during the process of synthesis, which was complied with the environmental requirements.The HNTs hydroxyl is covalently bonded to the polyurethane molecular chain during the synthesis of the prepolymer, which is involved in the whole reaction, and thus to affect the degree of phase separation and hydrogen bonding between the segments of the polyurethane chain and the HNTs rather than a simple phyical mixing. The polyurethane elastomer nanocomposites owing a linear structure were prepared. In addition, the synthetic process with simple and inexpensive was proposed. HNTs will have an immeasurable impact throughout the field of polyurethane elastomer.