| Toughening and modifying environmentally friendly material Poly(lactic acid)into antibacterial composites is an important direction of research at home and abroadnow. Judging from the research progress, many studies have proved that inorganicnanoparticles can enhanced the antibacterial property of PLA, while it’s useless forincreasing the mechanical properties and it costs a lot. So how to enhance theantibacterial properties and mechanical properties of the PLA nanocomposits underthe condition of low content of nano-ZnO is an significant which is also a full ofutility value subject.Based on that nano-ZnO particles can increase the antibacterial activity of PLA,for the first time, this work has taken the advantage of the theory that Chlorophyll canabsorption light energy, added the right amount of CCA to the composites ofPLA/nano-ZnO, expected that nanocomposits could absorb a large amount of lightenergy to achieve high photocatalytic antibacterial effect of nano-ZnO, which underthe condition of natural light and low levels of nano-ZnO, and realized the purpose oflow cost and better antimicrobial activity of composites.Utilizing PLA as the matrix resin, nano-ZnO as the antibacterial agent, CCA asthe light energy absorption agent, blending master batch was produced by the methodof melt blending. Using thermal mechanical of blending, the master batch, PLA andtributyl citrate (TBC) was blended into PLA/nano-ZnO/CCA which has differentformulations. The antibacterial properties, the mechanical properties, the rheologicalproperties, the thermal properties, the morphology and phase structure ofnanocomposites were studied through different kinds of instruments, such asuniversal testing machines, rotary rheometer, SEM, DSC, FTIR, TEM and so on. Theresults are concluded as follows:（1）There is an interaction between nano-ZnO and CCA, which has providedthe foundation for using CCA to enhance the photocatalytic antibacterial ofnano-ZnO. A moderate amount of CCA will obviously improved the antimicrobialactivity against E. Coli of PLA/nano-ZnO/CCA under visible light. PLA/nano-ZnO can show antibacterial (antibacterial rate≥90.0%) until nano-ZnO is more than1.5wt%. while after the addition of nano-ZnO=0.3wt%and nano-ZnO/CCA=18:6,the antimicrobial activity of nanocomposites against E. Coli was great, and hasincreased by9times. PLA/Nano-ZnO/CCA showed strong antibacterial propertiesagainst E. Coli when adding0.9wt%of nano-ZnO and nano-ZnO/CCA=18:6(antibacterial rate≥99.0%).（2）For the PLA/nano-ZnO composites, the impact strength, tensile strengthand bending strength were decreased as the existing of CCA, while the stress yieldbehavior was increased firstly then decreased. At the content of nano-ZnO is1.2wt%and the ratios of nano-ZnO/CCA is18/6, the antibacterial rate of the composites was99.5%; the elongation at break increased by18times, and92%,86%and76%of thetensile strength, bending strength and NIIS were still maintained.（3）The main viscoelastic behavior of composites was viscous, the system ofcomposites was poorly responsed to the frequency. Added nano-ZnO and CCA intocomposites can both reduce the storage modulus and Loss modulus.（4）The impact fracture morphologies of PLA/nano-ZnO/CCA observed byTEM showed that nano-ZnO particles were uniformly dispersed in the PLA matrixexcept for a low degree of aggregation which resulted in worsing of mechanicalproperties.（5）Adding a moderate amount of CCA can enhance the crystallization andreduce the thermal stability of composites. While after the addition ofnano-ZnO=0.9wt%and nano-ZnO/CCA=18:6, the initial thermal decompositiontemperature was decreased by16℃, and the crystallization of the composites wasincreased by8.4%. |
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