Functionalization Modification of the Fischer-Tropsch Wax to Improve the Mechanical and Crystallization Properties of the Recycled Polypropylene/Attapulgite Composites

The attapulgite (ATP) with unique one-dimensional rod-like structure was used to improve the mechanical and crystallization properties of the recycled polypropylene (rPP). In order to increase the compatibility of the polar ATP and the non-polar rPP, the maleic anhydride (MAH) was grafted onto the fischer-tropsch wax (FTW) then reacted with ATP to prepare FATP. The tensile, flexural and impact strength of the composites were maximized at the FATP content was 3 wt%, increased by 13.09, 17.56, and 101.92% compared with rPP, and reaching the level of the PP. Due to the improved compatibility, the mechanical properties of the rPP/FATP composites were increased compared with the rPP/ATP composites at the same addition. Moreover, the differential scanning calorimetry (DSC) analysis proved that the addition of the ATP or FATP improved the crystallization properties of the rPP. The crystallization temperature (Tp) of the rPP, rPP/3 wt% ATP, and rPP/3 wt% FATP was 126.31, 127.86, and 129.37 ℃, respectively. The non-isothermal and isothermal crystallization kinetic results showed that the crystallization rate was increased with the addition of the ATP and FATP. Meanwhile, by reason of the synergistic effect of compatibility improvement and internal lubrication, the crystallization rate of the rPP/FATP composites was faster than the rPP/ATP composites. However, the ATP or FATP added in rPP had no effect on the spherulites growth mode of the composites. Above all, the scanning electron micrographs (SEM) results provided intuitive evidence which the compatibility between FATP and rPP was greatly improved.