Structure And Properties Of Different Shape Nano-TiO₂/Thermoplastic Polyurethane Composite Fibers

Compounding is one of the important strategies to improve the mechanical and functional properties of polyurethane,and the properties and distribution of fillers are the key factors in determining the various properties of polyurethane composites.Firstly,different shapes of filler particles form different interfacial properties with the polyurethane matrix.Secondly,different shapes of filler particles are dispersed differently inside the polyurethane matrix.Thirdly,different shapes of filler particles are arranged differently under the action of forces.All these factors are closely related to the final properties of polyurethane composites.Therefore,the study of filler shapes and distribution is of great research significance for the preparation of polyurethane composite fibers with high mechanical properties.In this paper,spherical titanium dioxide,titanium dioxide whisker,and spherical titanium dioxide/titanium dioxide whisker hybrid particle polyurethane composite fibers were prepared using the nonsolvent-induced phase separation(NIPS)method under N,Ndimethylformamide/toluene binary solvent,respectively,and the effects of filling amount and filler shape on the microstructure and mechanical properties of the composite fibers were investigated.The dominant factors of the three particles affecting the strength of the interfacial properties of the polyurethane matrix were further analyzed.The main conclusions are as follows.(1)Spherical titanium dioxide/polyurethane composite fibers(PTCF)with different particle sizes were prepared.The incorporation of spherical titanium dioxide particles promoted the microphase separation of PTCF.Compared with TPU,the PTCF composite fibers had superior mechanical properties.When the filling amount was 1%,the stresses of PT4CF-1 and PT10CF-1 were elevated by 46.8% and 25.7%,respectively,and the strains were decreased by only 6.7% and 5.5% compared with TPU,,and the cyclic mechanical properties of the composite fibers were also better.(2)Titanium dioxide whisker and titanium dioxide whisker/polyurethane composite fibers(PWCF)were prepared.The titanium dioxide whisker has a rutile phase with stable structure.Compared with TPU,the PWCF composite fiber has superior mechanical properties.When the filling amount was 1%,the stress and strain of PWCF-1 were 52.1 ± 3.1 MPa and 1307.8 ±49.8%,respectively,which indicates that the titanium dioxide whisker can play a role in enhancing the stress of polyurethane fiber.(3)Spherical titanium dioxide/titanium dioxide whisker/polyurethane composite fibers(TW)were prepared.The effects of the mixed particles on the structure and properties of the polyurethane composite fibers at different ratios were compared.Also,the mechanics of TW composite fibers were compared with those of PTCF and PWCF composite fibers.Compared with PT4CF-1 and PWCF-1,the TW-55 composite fibers had superior mechanical properties,the stress of TW-55 was increased by 5.1 MPa(6.7%)and 23.3 MPa(30.9%),and the strain was increased by 0.4% and 20.6%,respectively,compared with PT4CF-1 and PWCF-1.The analysis of stress,strain,and toughness of different polyurethane composite fibers shows that spherical titanium dioxide particles provide toughening effect on polyurethane composite fibers,titanium dioxide whiskers provide strengthening effect on polyurethane composite fibers,and a certain proportion of spherical titanium dioxide/titanium dioxide whiskers mixed particles provide strengthening and toughening effects on polyurethane composite fibers.This method provides a new way to select different strain composite fillers under special conditions.