Rheology, mechanical properties and peel adhesion of hot-melt adhesive based on thermoplastic polyurethane/nanosilica

A series of thermoplastic polyurethane hot-melt adhesive formulations have been synthesized by melt blending of polyether-based thermoplastic polyurethane and different nanosilica, C5, and C9 hydrocarbon loadings. Different analyses, including FESEM, tensile strength, rotational rheometry, T-peel strength with polyester fabric, and nitrogen gas permeability, are conducted to examine the properties of the prepared adhesive formulations. The results show that the addition of 0.25 wt% of nanosilica increased the tensile properties of the polyurethane slightly and improved the T-peel strength with the polyester fabric. On the other hand, adding 5 wt% of C5 hydrocarbon tackifier reduced the tensile properties a bit, reduced the storage and loss modulus, and increased the T-peel strength with the polyester fabric. On the other hand, adding the C9 tackifier reduced the tensile strength more than the counterpart formulation including C5, reduced the storage and loss modulus and increased the T-peel strength. A noteworthy result was that the addition of nanosilica in the presence of C5 or C9 tackifiers lowered the loss and storage modulus and complex viscosity Adhesive formulation with 5 wt% of C5 tackifier has the highest average and maximum peel strength with about 20 and 35% higher strength than neat TPU.