Preparation And Properties Of PLA-based Multifunctional Fluorescent Composites

Rare earth luminescent polymer composites are widely used in anticounterfeiting,luminescence,display and other fields.In this paper,PLA based fluorescent composites with fluorescence effect were prepared by melting processing of rare earth doped fluorescent materials and polylactic acid(PLA)matrix,and their rheological,crystal and mechanical properties were studied in detail.In addition,high toughness poly(adipic acid)-butylene terephthalate(PBAT)was used to toughen PLA.On this basis,PLA/PBAT/ fluorescent powder composite was further prepared.The fluorescence,mechanical,crystallization and thermal properties of composites were studied.At the same time,a preliminary experiment on the color of fluorescent composite was carried out.The specific research contents are as follows:(1)The fluorescent composite material with green light at 365 nm excitation wavelength was prepared by melt processing and the related properties were characterized.The fluorescence test showed that the fluorescence effect of the composite increased with the increase of the fluorescent powder content.DSC curves showed that fluorescent powder promoted the crystallization process of PLA,and the addition of fluorescent powder effectively improved the crystallization capacity of PLA.The rheological curves showed that PLA appeared shear thinning with the addition of fluorescent powder.The mechanical properties test showed that the addition of fluorescent powder had a certain degree of toughening effect on PLA.Four dispersants were added on the basis of 10% fluorescent powder content.It was found that the addition of dispersants made it have better fluidity and enhanced the fluorescence intensity of the fluorescent composite.At the same time,it was found that the fluorescence intensity of the composite obtained by double-rotor mixing process was slightly higher than that obtained by twin-screw extrusion compounding process.(2)In order to improve the toughness of PLA matrix composites,PBAT was firstly used to blend PLA.With the addition of PBAT,the entanglement ability between molecular chains of binary blend system was enhanced,and the complex viscosity was improved.The viscosity of the blend system was stronger than the elastic properties.The mechanical properties test results showed that the addition of PBAT effectively improved the toughness of PLA,slightly reduced its tensile strength.It was found that the fluorescence intensity of PLA/PBAT/ fluorescent powder system increased with the increase of fluorescent powder content.In addition,the mechanical properties test showed that with the addition of fluorescent powder,PBAT and fluorescent powder had a synergistic toughening effect on PLA.DSC showed that the addition of fluorescent powder effectively improved the crystallinity of PLA.The thermal deformation temperature test showed that the addition of fluorescent powder effectively improved the thermal deformation temperature of the binary blend system.(3)In order to enrich the color properties of the fluorescent composite,a red fluorescent composite was prepared,and the color properties and rheological properties of the red fluorescent composite were studied.In addition,in order to make the fluorescent composite material have better fluorescence anti-counterfeiting effect,the dual-wavelength fluorescent anti-counterfeiting material was explored and prepared,and its luminous effect under different light sources was studied.