| Poly(butylene succinate)(PBS)is a green polymer material that can be biodegraded completely with excellent mechanical strength and thermal resistance,but its disadvantages of poor notch impact strength and slow degradation rate have limited its further application.Blending modification is a common modification of PBS,but it is difficult for the traditional blending modification to improve the mechanical properties,crystallization properties and degradation properties of PBS at the same time.In this study,variety of biodegradable polyester elastomer particles(BEP)with controllable particle sizes and rich in hydroxyl,carboxyl and sodium carboxylate respectively were prepared,and then some PBS/BEP composites were fabricated by using the simple melt-blended method.The effects of particle sizes,rich groups and loading of the BEPs on mechanical properties,crystallization properties and degradation properties of PBS composites were investigated specially.1.Preparation of some PBS/BEP composites.Two kinds of unsaturated polyester with hydroxyl and carboxyl terminal groups were prepared from aliphatic diol,dibasic acid(or acid anhydride)and polyethylene glycol 400.Two types of BEPs rich in hydroxyl(HBEP)and two types of BEPs rich in carboxyl(CBEP)were prepared by emulsification,radiation crosslinking and spray drying of unsaturated polyester,and the particle sizes of HBEPs were 70 nm and 150 nm respectively,the particle sizes of CBEPs were 100 nm and 190 nm respectively.Then the Na HCO3 was used to neutralize two types of CBEPs to prepare saline BEPs(SBEP).Then the BEPs were melt-blended with PBS respectively to prepare some PBS/BEP composites.2.Study on mechanical properties of the PBS/BEP composites.The results of mechanical performance test of PBS/BEP composites show that the elongation at break and the notched impact strength of PBS/BEP composites can be increased obviously by adding BEPs.Moreover,the CBEPs have the best effect on the increasing of mechanical properties of PBS.The CBEP with the particle size of 190 nm can increase the elongation at break of PBS/BEP composites from 265% of pure PBS does to 483%,and increase the notched impact strength to the double of pure PBS.Scanning electron microscope(SEM)images show that the roughness of the impact and tensile fracture surfaces of PBS/BEP composites increase after adding BEPs,however,the BEPs in the matrix appear obvious agglomeration phenomenon,when the loading of BEPs attain 10 phr.3.Study on the crystallization properties of the PBS/BEP composites.Differential scanning calorimeter(DSC)results show that the crystallization properties of PBS could be improved by adding no more than 5 phr content of HBEPs or SBEPs,but the CBEPs could hinder the crystallization of PBS.The crystallization properties of PBS are best improved by adding the SBEP with small particle size.The half crystallization time of PBS at isothermal crystallization(95 °C)is shortened 41%,and the crystallization rate constant is increased to 18 times of pure PBS with 5 phr loading of SBEP(100 nm).X-ray diffraction(XRD)results show that BEPs can’t change the crystal form of PBS/BEP composites,but increase the degree of crystallinity of PBS at isothermal crystallization.4.Study on degradability and cell compatibility of the PBS/BEP composites.BEPs can increase the degradation rate of PBS in lipase environment,water solutions with different p H and soil environment,and the degradation rate increase with the increasing of BEP content and the decrease of particle size.The weight loss rate of PBS/BEP composites with 10 phr loading of SBEP(100 nm)is 9 times of pure PBS in lipase environment after degradation of 15 days,40 times of pure PBS in Na OH solution(p H=13)after degradation of 25 days,and 2.3 times of pure PBS in soil environment after degradation of 4 months.The results of Thiazole Blue(MTT)colorimetry assay tests show that PBS/BEP composites have no obvious cytotoxicity,and the relative growth rates are all above 75%. |
PDF Full Text Request