Enhancing morphology and compression properties of halloysite reinforced polyurethane nanocomposites using injection-moulding technique

Abstract

The traditional method of enforcing thermoplastic polyurethane (TPU) by halloysite nanotubes (HNTs) to create HNTs-TPU nanocomposite material has been modified aiming at producing better quality nanocomposite using compression injection techniques. This technique adds more options of using control parameters and much better estimation to the corresponding levels of these parameters. In this study, six controlled parameters of injection temperature, injection pressure, mould temperature, injection time, HNTs loading, and function HNTs at three levels were considered. Under such huge number of parameters and their corresponding levels, the number of required experiments is enormous; however, with the help of Taguchi method of orthogonal arrays, the number of experiments is reduced to only 27. These experiments are then used to examine the optimized conditions of modulus Young’s, compression strain, and compression extension (known as responses). In this study, Taguchi method is fortified by ANOVA since Taguchi method is not enough to provide a clear and full analysis. The responses of modulus Young, compression strain, and compression extension have shown maximum absolute variation based on the original and untreated material by 30%, 25%, and 37%, respectively. Further, the optimized modulus Young is optimized at 1 wt% HNTs, 4 bar of injection pressure, 28 °C of mould temperature, and 4 min of injection time. These results were confirmed statistically by ANOVA and experimentally by field emission scanning electron microscopy (FESEM) images where the agglomeration of HNTs was seen as an important factor of the absolute variation of the responses. This study serves another purpose where Taguchi method was tested for reliability in a very big scale of such control parameters. Keywords: Nanocomposites, Design of experiment, Taguchi method, Compression properties