Preparation And Performance Study Of 3D Printing PLA/PBSA/HA Composites

The number of patients with bone defects is increasing year by year due to congenital monstrosity,traumatic tumor diseases and accidental traffic accidents.However,the bone tissue living organ donors are limited,the matching is difficult,and there is a contradiction between supply and the huge demand of many patients for tissue grafts.Therefore,bone tissue engineering has promising development prospects.As a new type of additive manufacturing process,3D printing has the advantages of no need for custom molds,low development cost,short production cycle and high molding accuracy.It can be customized according to different conditions of different patients,and has great advantages compared with traditional manufacturing methods.In recent years,it has gradually received attention in the medical field.Polylactic acid(PLA)has the advantages of high strength,high modulus,and easy processing,which is a hot spot in the research of biodegradable materials.However,wide application of PLA has limited by the disadvantages of poor toughness and slow crystallization rate.Polybutylene succinate-butylene succinate copolymer(PBSA)is a degradable aliphatic polyester with good toughness.Mixing PBSA with PLA can improve the impact strength of PLA,and does not affect the degradation performance of the material.Hydroxyapatite(HA)is the main inorganic component of bone.HA can increase the strength and biological activity of the composites,which makes it to be a good bone repair material.In this paper,PLA/PBSA/HA composites of different proportions were prepared by melt blending method,and the properties of PLA/PBSA composites of different proportions and the printing properties of PLA/PBSA/HA composites were investigated.The main contents and conclusions are as follows:(1)A series of PLA/PBSA composites were prepared by melt blending method.The structure and properties of PLA/PBSA composite swere studied by Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry(DSC),polarizing microscope(POM),thermal weight loss analysis(TGA),and atomic force Microscopy(AFM)and so on.The results show that the PLA crystal morphology changes from radial spherulites to ring-shaped spherulites with the addition of PBSA,and the size of the spherulite ring-strip increases.The DSC and TG test results show that the cold crystallization temperature of PLA increases first and then decreases due to the addition of PBSA.The composite has good thermal stability and the crystallinity decreases with the increase of PBSA.The results of mechanical tests show that the toughness of PLA /PBSA composites increases with the addition of PBSA.When the PBSA content is 20%,the elongation at break and the impact strength are the highest,which are 559% and 107% higher than those of pure PLA,respectively.The fracture surface morphology of the composites confirmed that the composites changed from brittle fracture to ductile fracture.(2)PLA / PBSA composite material with PBSA added at 20% was selected as the research object,and HA with 1%-15% content was added to prepare PLA/PBSA/HA ternary composite material.The effect of the introduction of HA on the composite material was studied.The results show that HA plays the role of heterogeneous nucleation.As the amount of HA added increases,the size of the spherulites decreases and the number of spherulites increases.The addition of HA improves the bending performance of PLA/PBSA/HA composite materials.When the HA content is 15%,the flexural strength and flexural modulus of the composites are increased by 7.29% and 36.79%,respectively.The analysis of AFM test results indicated that HA was mainly distributed at the PBSA phase and the interface between PLA and PBSA phase.(3)Samples were successfully prepared using fused deposition molding(FDM),and the effects of process parameters such as print substrate temperature,print layer thickness,and print speed on the samples were explored.The results show that the best quality of the sample is obtained when the temperature of the printing substrate is 70 ℃,the thickness of the printing layer is 0.1 mm and the printing speed is 60 mm/s.When PBSA content is 30% and below,it acts like a lubricant in the printing process,and the print quality is improved.The mechanical properties test show that the specific strength of the printed sample of the composite is slightly lower than that of the injection molded sample,but the impact strength of the printed sample is significantly higher than that of the injection molded sample.The specific impact strength of the printed PLA/PBSA/5%HA sample was 40.5% higher than that of the injection sample.The AFM test results show that the microphase structure of the composite material is affected by the molding process.The PBSA phase is elliptical in the extruded samples,long rods with obvious orientation in the injection samples,and thin strips with smaller diameters in the printed samples.It was found that the two-phase interface in the printed sample was more blurred,indicating that the printing improved the compatibility of PBSA and PLA to a certain extent.(4)The quality and p H rate of PLA/PBSA/HA composites were slowed down because HA reduced the autocatalytic effect of PLA.The degradation rate of all samples showed a trend of slow and then fast.During the degradation period,the p H value of all samples was above 7.0 and the weight loss rate was below 5%,indicating that the material performance was stable.The biosafety test showed that the PLA/PBSA/HA composite had no toxicity,no thermogenesis,no sensitization and no hemolysis effect,which can meet the basic requirements of bio-scaffold materials.