Modifications Of Polypropylene Fiber And FIBC Model Blends With Halloysite Nanotubes

In this thesis, naturally occurring halloysite nanotubes (HNTs) were applied in the modification of polypropylene fiber (PP fiber) and a model blend for flexible intermediate bulk containers (PP/PET=90/10, FIBC-MB). The preparation, structure and properties of PP/HNTs nanocomposite fibers and FIBC-MB/SEBS-g-MAH/HNTs nanocomposites were investigated.A masterbatch method was optimized to prepare PP/HNTs nanocomposite fibers with better mechanical performance and spinnablity. This technology has been attempted industrially. The PP/HNTs nanocomposite fibers fabricated by this mothod exhibit uniform dispersion of HNTs and better spinnability compared with the direct blending method. Meanwhile, mechanical test results show that the tensile strength of PP/HNTs nanocomposite fibers is higher than the neat PP fiber at the same extension ratio. For instance, by incorporating 1 wt% of HNTs, the breaking strength of PP/HNTs have an increase of 18.6%. Moreover, HNTs has an effect in improving thermal stability, crystallinity and crystallization temperature.The modification of FIBC-MB with HNTs and elastomers were investigated. FIBC-MB/SEBS-g-MAH/HNTs nanocomposites were prepared by two-step process. HNTs and elastomer show synergistic effect in compatibilizing and toughening FIBC-MB. Under optimized composition, the impact strength is increased by 118% without sacrificing the tensile strength and stiffness. The present technology provides a unique insight in recycling FIBC waste industrially.The mechanical properties, crystallization behavior and morphology of FIBC-MB/SEBS-g-MAH/HNTs nanocomposites were investigated. Based on the morphological observations, a SEBS-g-MAH elastomer encapsulation model was proposed. HNTs were found dispered uniformly in the matrix by strong shearing and interaction between HNTs and the elastomer. Besides, the surfaces of HNTs were encapsulated by elastomer, which effectively improves the compatibilities among the components via interface overlapping. TEM observations show that part of HNTs are restricted in boundary layers, these HNTs can perform a role as"rebar"in the nanocomposites, which facilitates the transfering and absorbing of the stress. For instance, by incorporating of 5phr of HNTs, the tensile strength, impact strength, flexural strength and flexural modulus of FIBC-MB/SEBS-g-MAH/HNTs nanocomposites are improved by 4.2%, 14.1%, 16.1% and 12.2% compared with directly compound method, respectively. HNTs play a significant role as heterogeneous nucleation agent in the composite system. The crystallization temperature, cystallinity and crystallization rate of FIBC-MB/SEBS-g- MAH/HNTs nanocomposites are enhanced with the increasing of the content of HNTs.