Investigations On The Fabrication Of Multi-functional Polyoxymethylene Composites Based On Ionic Liquid

As one of the five important engineering plastics,polyoxymethylene(POM)has been widely used in automotive,electronic and electrical,medical equipment and other fields due to its excellent comprehensive properties.However,the performance of POM itself can no longer meet the industrial needs.Therefore,it's a hot issue to fabricate multi-functional POM composites.Focusing on the drawbacks of the high electrical insulation,low notched impact toughness and friction performance that needs to be further improved of POM,we innovatively used one kind of ionic liquid(IL),Tribuyl-(octyl)phosphonium Bis(trifloromethanesulfonyl)imide(TBOP-TFSI),as multi-functional modifier to improve the properties of POM,and the ionic liquid was compounded with traditional modifier,multi-walled carbon nanotubes(MWCNTs)and polytetrafluoroethylene micro-powder(PTFE),to fabricate POM composites with excellent comprehensive performance by simply melt mixing.It is hoped that the POM composites could be antistatic,and the crystallization and friction properties of POM can be improved as well.The effects of TBOP-TFSI,TBOP-TFSI with MWCNTs or PTFE on the structure and properties of POM were investigated systematically.The main contents and conclusions are as follows:(1)The study on the structure and properties of POM/IL blends: The POM/IL blends were fabricated through simultaneous melt-mixing and then the detailed structure and properties of the blends were characterized by FT-IR,SEM,DSC,and so on.It was indicated that TBOP-TFSI was partially compatible with POM due to the electrostatic interaction between anion of ionic liquid and C-H bond on POM,so that a trace amount of TBOP-TFSI could be evenly dispersed in POM matrix.At the meantime,TBOP-TFSI had nucleating effect on POM which means that the addition of TBOP-TFSI improved the crystallization temperature and crystallinity of POM,reduced its spherulites' size.What's more,a trace amount addition of TBOP-TFSI endowed POM good antistatic properties,and improved its notched impact strength and elongation at break while maintaining the good tensile strength.TBOP-TFSI is good for the fabrication of POM composites with excellent comprehensive properties.(2)The study on the structure and properties of POM/IL-MWCNTs composites: TBOP-TFSI was coated to the surface of MWCNTs by simply grinding because of the interaction between O=S=O bond on the anion of TBOP-TFSI and MWCNTs.Then,the modified MWCNTs(IL-MWCNTs)were melt-blended with POM to prepared POM/IL-MWCNTs composites.IL-MWCNTs dispersed well in the POM matrix.The ionic liquid and MWCNTs have a synergistic nucleation effect on POM,which can promote the crystallization and reduce the spherulite size of POM composites,resulting in the improvement of tensile strength while maintaining the notched impact toughness.Moreover,the incorporation of TBOP-TFSI and MWCNTs can further improve the antistatic property of POM composites.(3)The study on the structure and properties of POM/PTFE/IL composites: POM/PTFE/IL composites were fabricated by melt mixing.It was found that the ionic liquid had a certain interaction with both PTFE and POM,so that the interface between the POM matrix and PTFE was enhanced,and the interfacial adhesion was improved.At the same time,the ionic liquid and PTFE had a synergistic nucleation effect on POM,which promoted the crystallization and reduced the size of POM spherulites.Therefore,the addition of the ionic liquid and PTFE imparted good antistatic properties and improved the friction properties of POM.In conclusion,the preparation of multifunctional POM composites was achieved.