Preparation And Properties Of Poly(Lactic Acid) Grafted With Butyl Acrylate

In the past few decades,PLA is the most commonly used raw material of plant-derived carbohydrate,such as starch in corn,etc.It is rich in source and renewable,and polylactic acid has biodegradability.Therefore,it has attracted great attention in environmental,biomedical and medical applications and alternative products of petroleum-based polymers.However,The inherent shortcomings of PLA such as low HDT(Heat Deflection Temperature)and high brittleness,restrict the application of PLA,so the researchers are committed to modifying PLA to meet the application needs.In this paper,butyl acrylate(BA)grafted poly(lactic acid)(PLA-gBA)was prepared by melting method with tributyl citrate(TBC)as plasticizer,in order to improve its flexibility.Firstly,the effects of reaction temperature and time on the grafting rate of PLA-g-BA were studied.The results showed that when the reaction time was 6 minutes and the reaction temperature was 180 ?,the highest grafting rate was 1.07%.Although the corresponding tensile strength decreased from 57.3 MPa(neat PLA)to25.3 MPa,the elongation at break was 484.2%,which was about 50 times of neat PLA(9.7%).The structure of PLA-g-BA was characterized by using infrared spectroscopy and nuclear magnetic resonance spectroscopy.Secondly,the effects of dicumyl peroxide(DCP),dibenzoyl peroxide(BPO),tert butyl peroxide(TBEC)on the mechanical properties were studied,the results showed that the tensile strength of PLA-g-BA was lower than that of neat PLA-g-BA,but the elongation at break of PLA-gBA was higher than that of neat PLA.The tensile strength of PLA-g-BA initiated by DCP,BPO and TBEC decreased from 57.3MPa(neat PLA)to22.5 MPa,23.7 MPa and 25.3 MPa,respectively,and the elongation at break increased from 9.7%(neat PLA)to 498.2%,360.1% and 484.2%,respectively.Therefore,the tensile strength of PLA-g-BA initiated by TBEC was the highest,and the elongation at break was also higher.Thirdly,the effects of the dosage of TBEC and BA on the grafting rate,thermal properties,mechanical properties and impact resistance of PLA-g-BA were studied.The results showed that the grafting rate of PLA-g-BA was the highest when the dosage of TBEC is 0.5 phr and BA is 10 phr,and its thermal stability was lower than neat PLA.With the addition of TBEC and BA increasing,the grafting rate of PLA-G-BA showed a trend of first increasing and then decreasing.And the tensile strength of PLA-g-BA decreased,but the elongation at break and notched impact strength increased significantly,indicating that the flexibility of PLA-g-BA was significantly improved compared with neat PLA.Finally,using neat polylactic acid and PLA-g-BA as 3D printing wire,the dumbbell-shaped sample was printed longitudinally.The test results of mechanical properties show that the interlaminar bonding strength of PLA-g-BA is 38.54 MPa,which is 19.6% higher than that of pure polylactic acid(32.22 MPa).