The Effect Of Doping Boron Nitride, Zirconia And Graphene On The Properties Of Polyhydroxyalkanoate Based Composites

Petroleum-based polymers,as a kind of traditional polymeric materials,have been applied in various areas.However,due to difficulty in recycling and reuse,they have brought enormous burden to the environment.To solve this problem,researches have focused on the study of natural polymeric materials as a substitute.Polyhydroxyalkanoate（PHA）,which has superior biodegradability and bio-compatibility,has received high attention and been widely applied as packaging,textile and injection mold materials,especially in the bio-medical field.Nevertheless,PHA also has some shortcomings in performance,such as limited mechanical property and thermal stability,which restrain its further application.Therefore,overcoming these defects will create a broader application potential for PHA material.In the current study,PHA was chosen as matrix,boron nitride（boron nitride micropaltes（BNMPs）,boron nitride nanospheres（BNNSs）and boron nitride nanofiber（BNNFs））,zirconia（ZrO₂）and graphene（GR）were used as fillers to prepare multiple series of PHA based composites,with different percentages of fillers.The effects of morphology,surface modification and filling content on the mechanical,thermal and hydrophilic properties of PHA have been investigated extensively.It was shown that boron nitride materials improved the tensile strength but decreased the elongation at break of PHA.Compared with BNMPs and BNNSs,BNNFs increased the tensile strength of PHA most significantly and maintained its original toughness best.Z-BNNFs,modified by ethyl nitrate,enhanced the tensile strength of PHA most significantly,by increasing the tensile strength to 39.56 MPa at the 6 wt%filling content,which is 90.28%compared to the neat PHA.The thermal stability and hydrophily of PHA were also improved largely.The addition of zirconia or graphene materials improved the tensilestrength of PHA,but weakened its toughness.The modified K-ZrO₂ and K-GR enhanced the tensile strength of PHA more remarkably.In the meantime,zirconia and graphene also promoted the thermal stability and hydrophily of PHA.