Preparation And Properties Of Microcrystalline Cellulose And Nano-montmorillonite Reinforced Poly (?-caprolation) Composites

Poly(?-caprolactone)(PCL)is an important biodegradable plastics,with great prospects in the fields of biomedicine and tissue engineering.However,PCL exhibits the drawback of low modulus,restricting its wider applications.Adding rigid fillers is an important means to enhance PCL.In this paper,the effects of microcrystalline cellulose(MCC)and organically modified montmorillonite(OMMT)on the properties of PCL were investigated,respectively.In order to improve the interfacial adhesion between PCL and fillers or reduce the costs,biodegradable cellulose ester derivative,cellulose acetate butyrate(CAB),was introduced as the third component in this work.The main results are as follows:(1)The preparation and properties of PCL composites reinforced by MCC.PCL/MCC composites and relevent PCL/MCC composites compatibilized by three different grades of CAB were prepared by melt mixing.The nonisothermal crystallization behavior of PCL and its composites was investigated by using differential scanning calorimetry(DSC).The results show the crystallization temperature of PCL moves to higher temperature with the addition of MCC,promoting the crystallization of the matrix.Further addition of CAB inhibits the crystallization of PCL,evidenced by the observation that the crystallization temperature moves to lower temperature.The Avrami equation was used to analyze the crystallization kinetics of the DSC data.The results show that the introduction of MCC and CAB does not change the crystallization mechanism of PCL apparently.The isothermal crystallization results from polarizing microscope(POM)show that the addition of MCC increases the nucleation density of PCL.Further addition of CAB decreases its nucleation density.Wide angle X-ray diffraction(WAXD)results show that the introduction of MCC and CAB does not change the crystal structure of PCL.The thermogravimetric analyses(TGA)show that the introduction of low content of MCC(?10 wt%)significantly improves the thermal stability of the PCL matrix,while further addition of CAB hardly promotes the thermal stability of the matrix.The tensile testing results show that the addition of MCC enhances the tensile modulus of PCL,with a maximum improvement of 40% compared with that of PCL,while further addition of CAB has little effect on the tensile modulus of the matrix.(2)The preparation and properties of OMMT reinforced PCL/CAB nanocomposites.The nanocomposites were prepared by melt mixing.The WAXD and transmission electron microscopy(TEM)results show that the polymer segments enter the organically modified montmorillonite interlayers,and the intercalated nanocomposites are obtained.Moreover,the WAXD results indicate that the introduction of OMMT and CAB does not change the crystal structure of PCL.The nonisothermal and isothermal crystallization behavior of the nanocomposites was investigated by DSC,and the crystallization kinetics was analyzed with the Avrami equation.The results show that CAB inhibits the isothermal crystallization of PCL.Further addition of OMMT improves the crystallization of PCL.The introduction of OMMT and CAB does not alter the nonisothermal and isothermal crystallization mechanism of PCL.The isothermal crystallization results from POM show that CAB reduces the nucleation density and decreases the crystallization rate of PCL,while the effects of OMMT are in contrast.TGA analyses show that the introduction of OMMT does not improve the thermal stability of the PCL/CAB matrix.The tensile testing results show that the introduction of OMMT enhances the tensile modulus of PCL/CAB blends by 45% without sacrificing the toughness of the matrix.