Research On 4D Printing Technology Of CF/PLA Shape Memory Polymer

With the continuous development of science,intelligent materials,as a new type of material,open a new era of material application.Among them,shape memory polymer is a kind of mature intelligent material.Under external stimulation,it can produce response.Shape memory polymer has many advantages,such as good biocompatibility,biodegradability,design of driving mode,light weight and low price.Poly(lactic acid,PLA),also known as poly(lactide),is a polyester polymerized from lactic acid.It is a kind of biodegradable material,which has good mechanical and physical properties,and has the use requirements of the space station cabin environment.It is an important material for the use of the space station cabin environment.Carbon fiber(CF)is a kind of high strength and high modulus fiber with carbon content of 90%.The mechanical properties of PLA modified by carbon fiber are improved,which can make PLA deform under control.Through the 4D printing of CF/PLA,it can realize the high density folding structure and functional devices.The thermal properties of PLA were studied by TGA and DSC.The dynamic thermomechanical analysis(DMA)was used to study the thermomechanical properties of PLA.The polylactic acid prepared in this paper is a thermotropic shape memory polymer.The shape memory properties of polylactic acid,single channel CF/PLA and cross channel CF/PLA were studied by three parameters of shape fixation rate,shape recovery time and shape recovery rate.The experimental results show that PLA has good shape memory performance and fast recovery speed,and the fixation rate of PLA is very high,reaching more than 99%;the recovery rate is also high,reaching more than 99%.In the shape memory test of single CF/PLA specimen,the specimen will be bent due to heating.Compared with PLA,the recovery speed of single CF/PLA specimen is obviously faster.At last,the single CF/PLA specimen is slightly bent to one side,which can not completely return to its original shape,and the recovery rate is generally above 85%.The fixation rate of single CF/PLA specimen is very high,reaching over99%.In the experiment of shape memory performance of cross CF/PLA specimen,the recovery speed is obviously faster than that of PLA specimen.Finally,the cross CF/PLA specimen bends slightly to one side.Compared with the single CF/PLA specimen,the bending radian of cross CF/PLA specimen is smaller,which can not completely return to the original shape,and the recovery rate is higher,reaching more than 88%.The fixation rate of single CF/PLA specimen is very high,reaching over 99%.Due to the different thermal expansion coefficient between the polylactide layer and the carbon fiber layer of CF/PLA,the expansion size is also different,which makes the material bend.When the CF/PLA specimen is heated,due to the small thermal expansion coefficient of PLA,one side of carbon fiber expands gradually,and the bending direction changes gradually.When the temperature increases,the specimen bends towards the carbon fiber side;when the temperature decreases,the specimen bends towards the polylactic acid side.In recent years,origami is also becoming a technical tool.At present,computational origami is a field of computer science,which has many practical applications.The origami structure derived from Miura ora unit and Miura ora unit has been widely used in the field of engineering and architecture.In this paper,we use SolidWorks to build three-dimensional models of Miura ora unit structure and the first derivative structure of Miura ora unit,import the established models into Cura software in turn,then import the sliced models into 3D printer,and print them out with polylactic acid as raw material.The recovery performance of Miura ora cell structure and the first level derivative structure model of Miura ora cell are tested.By testing the shape memory performance of Miura ora unit structure and the first derivative structure of Miura ora unit,it can be concluded that the shape fixation rate and shape recovery rate of Miura ora unit structure and the first derivative structure of Miura ora unit are above99%,and the shape memory performance of Miura ora unit structure and the first derivative structure of Miura ora unit is good,which can be based on the structure It can be used in 4D printing.Based on origami technology,this paper designs a grabbing structure.Using SolidWorks drawing software to make three-dimensional model of the designed grabbing structure,import the established model into Cura slicing software,slice it,print the grabbing structure with 4D printing technology,test the recovery ability of the grabbing structure by printing the grabbing structure with different crease thickness,and analyze the impact of the crease thickness on the recovery performance of the grabbing structure;Verify the deformation ability of grab structure under temperature stimulation.It can be concluded that the fixed rate of the grabbing structure is very high,reaching over 96%;the recovery rate is also high,reaching over 92%.The recovery rate of the grab structure with 0.4mm crease thickness is the best,96.23%.Through the experiment,it can be concluded that the higher the temperature is,the higher the recovery rate is.The CF/PLA grabbing structure is printed by 4D printing technology,and the recovery performance of CF/PLA grabbing structure model is tested.The recovery rate of CF/PLA grabbing structure is very high,over 98%.Through the experiment,it can be found that the recovery speed of CF/PLA grabbing structure is obviously faster,and the recovery speed of carbon fiber adding end is faster than that of carbon fiber adding end,and the fixed rate and recovery rate of CF/PLA grabbing structure are also higher than that of grabbing structure.