This article addresses the effect of nano-SiO₂ on the morphology, crystallization and dynamic mechanical properties of polyamide 66. The influence of nano-SiO₂ on the tensile fracture morphology of the nanocomposites was studied by scanning electron microscopy (SEM), which suggested that the nanocomposites revealed an extensive plastic stretch of the matrix polymer. The crystallization behaviour of polyamide 66 and its nanocomposites were studied by differential scanning calorimetry (DSC). DSC nonisothermal curves showed an increase in the crystallization temperature along with increasing degree of crystallinity. Dynamic mechanical properties (DMA) indicated significant improvement in the storage modulus and loss modulus compared with neat polyamide 66. The tan ä peak signifying the glass-transition temperature of nanocomposites shifted to higher temperature.

In recent years, foam materials have attracted people’s attention in many fields. This study reveals the onestep preparation of polypropylene (PP) foam material with very low carbon nanotubes (CNTs) content via laser irradiation technology. A low-energy near-infrared (1064 nm) laser beam is used to scan the laser-sensitive PP/CNTs composite prepared in the air. The controllable instantaneous thermal energy generated by laser irradiation decomposes CNTs and PP, and forms a foaming layer in situ on the surface of the composite material. CNTs content, laser power and laser scanning rate are key parameters for controlling laser-induced foaming. The results show that the rich carbonized structure induced by the laser envelops the gas generated by thermal degradation to form a porous structure, and form a 3D white pattern with the naked eye. This study can provide a positive reference for directly writing 3D foamed structures on the surface of composite materials on a large scale through a simple and efficient one-step laser irradiation method.