Preparation And Properties Of Thermoplastic Polyurethane-based Nanocomposites

Thermoplastic polyurethane(TPU)has excellent low temperature resistance,wear resistance,oil resistance,high resilience and other advantages,showing great application prospects in national defense,national life,medical and other aspects.However,the mechanical strength,heat resistance and water resistance of TPU are still unsatisfactory,which limits its further application.Modification of TPU with nano materials is an important method to improve the comprehensive performance of TPU.In this paper,using 1.05 as R value,diphenylmethane diisocyanate(MDI)as isocyanate raw material,polyethylene adipate 2000(PEA2000),polytetrahydrofuran 2000(PTMG2000),phthalic anhydride polyester polyol 2000(APP2000)as oligomer polyol raw material,1,4'-butanediol(BDO),ethylene glycol(EG)and diethylene glycol(DEG)as chain extender and one-step method as synthesis method,a series of TPU materials with different hard segment contents(25%,30%and 35%)were synthesized.The synthesis parameters of TPU matrix were determined as follows:soft segment was PEA2000,chain extender was BDO and hard segment content was 30%.The tensile strength of TPU matrix was 18.94MPa,elongation at break was936.1%,water absorption was 1.19%(25?)and 7.06%(85?),and the comprehensive properties were preferably.On this basis,nano silica(SiO₂)and attapulgite(ATP)were modified by silane coupling agent KH550 to obtain modified nano silica(K-SiO₂)and modified ATP(K-ATP).TPU/K-SiO₂,TPU/K-ATP and TPU/K-SiO₂/K-ATP(TPU/KS/KA)composites were prepared by one-step in-situ polymerization.The composites were characterized by Fourier transform infrared spectroscopy(FT-IR),differential scanning calorimetry(DSC),field emission scanning electron microscopy(SEM),microcomputer-controlled electronic universal testing machine,static contact angle tester and water absorption test.The results showed that K-ATP enhanced the hydrogen bonding degree of TPU and decreased the glass transition temperature of TPU soft segment with 18.2?.When the K-ATP content was 2wt%,the 50%TGA temperature of TPU increased from 367.42?to 382.70?,and the tensile strength increased from 18.94MPa to 29.66 MPa;The surface hydrophobicity of TPU was enhanced by K-ATP and the water absorption decreased to 5.60%(85?).The introduction of K-SiO₂ slightly increased the number of hydrogen bonds in TPU and decreased the glass transition temperature of soft segment of TPU by 3.1?.The degree of microphase separation of TPU was improved.When the content of K-SiO₂reached 2wt%,the 5%thermogravimetric temperature of TPU increased from 285.78?to 289.47?,and the thermal stability was enhanced.TPU/K-SiO₂(2wt%)had the maximum tensile strength(49.59MPa)and elongation at break 1691.63%.The water absorption of TPU decreased to 3.66%(85?)The combination of K-SiO₂ and K-ATP increased the number of hydrogen bonds and the formation of microregions in hard segment in TPU.The combination of K-SiO₂ and K-ATP decreased the glass transition temperature in soft segment by 6.3?and improved the degree of microphase separation in TPU.The mechanical properties of TPU were enhanced by the cooperation of K-SiO₂ and K-ATP and the tensile strength of TPU/KS1/KA1 was the best with51.66MPa,showing a better synergistic modification effect of K-SiO₂ and K-ATP.The thermal stability of TPU was improved by introducing the K-SiO₂ and K-ATP,and the TPU/KS/KA thermal weight loss temperature of 5%and 50%increased by 6.7?and 6.9?,respectively,on the basis of pure TPU.The surface hydrophobicity of TPU/KS/KA was enhanced,and the water absorption rate of TPU/KS1/KA1 was the lowest,which decreased from 7.06%to 3.07%,indicating that K-SiO₂ and K-ATP had better synergistic modification effect.