Study On The Preparation And Properties Of PA6-g-MWNTs Composite Fibers

Nylon6(PA6)is a kind of excellent performance of polymer material,which has many advantages such as high strength,good processing flowability,good wearability,good corrosion resistance etc.,and some disadvantages such as poor thermal stability,strong water-absorbing,low impact strength at dry state and low temperature environment etc.at the same time,making its application is restricted.CNTs is a very kind of reinforcement in polymer matrix composites,and it is used to study of modified nylon,but the research is less in nylon grafting CNTs.At present,the methods of grafting multi-walled carbon nanotubes(MWNTs)on the surface of PA6 mainly includes anionic ring-opening polymerization and microwave irradiation polymerization.PA6 grafting MWNTs(PA6-g-MWNTs)prepared by the former method is difficult to spinning due to the small molecular weight of PA6 in PA6-g-MWNTs,and large amount of highly toxic substances need to be use in this method;in the latter method,the preparation condition is rigorous,at the same time,the internal and surface temperature of the reactants is uneven distribution,so this is hard to approach for industrial production.To solve above problems,this paper gives an idea to give full play to the performance of MWNTs to improve the mechanical properties of PA6,PA6 grafting polystyrene maleic anhydride(SMA)(PA6-g-SMA)are prepared by PA6 and SMA through a grafting reaction firstly,then amino-functionalized MWNTs(MWNTs-NH2)are prepared by MWNTs through ammoniation processing,PA6-g-SMA composite fibers are prepared by PA6-g-SMA and MWNTs-NH2 through melting reaction and spinning at last.In this paper,firstly,PA6-g-SMA were prepared by PA6 and SMA through a grafting reaction,the effect of the preparation process on the properties of PA6-g-SMA were studied via weighing method,including the mass ratio of SMA and PA6,the reaction temperature and reaction time;the structure and properties of PA6-g-SMA were characterized by FT-IR,DSC and TGA.Then,oxidized MWNTs(MWNTs-COOH)were prepared by an oxidization,and then MWNTs-NH2 were prepared by MWNTs-COOH reacting with ethylenediamine(EDA)through a composite catalytic system including N'N-dicyclohexylcarbodiimide(DCC)and 4-dimethylaminopyridine(DMAP),the structure and properties of MWNTs-NH2 were characterized by FE-SEM,FT-IR,TGA,XRD and Raman.Finally,PA6-g-MWNTs composite fibers were prepared by PA6-g-SMA and MWNTs-NH2 through amidation reaction and spinning,the effect of the preparation process on the properties of PA6-g-MWNTs composite fibers were studied via fiber strength tester,including the mass fraction of MWNTs-NH2,the reaction time,the spinning temperature,the winding speed,the draw ratio and temperature;the structure and properties of PA6-g-MWNTs composite fibers were characterized by FE-SEM,FT-IR,TGA,XRD and fiber strength tester.The results of the effect of the preparation process on the properties of PA6-g-SMA indicated that with increasing of the mass ratio of SMA and PA6,the grafting ratio of SMA in PA6-g-SMA increased firstly then decreased;with increasing of the reaction temperature and reaction time,the grafting ratio of SMA in PA6-g-SMA all increased firstly,then remain unchanged.The results of the structure and properties of PA6-g-SMA indicated that PA6-g-SMA was prepared by PA6 and SMA through an amidation reaction;the melting point of PA6-g-SMA was 190?,shorter than PA6;the thermal decomposition temperature range of PA6-g-SMA were 398.5?-463.7?.The results of the structure and properties of MWNTs-NH2 indicated that through oxidization functionalized,MWNTs were linked with carboxyl groups,the length of MWNTs-COOH were shorter than raw MWNTs,and the structure of the MWNTs-COOH had a certain extent destruction compared with raw MWNTs;through ammoniation functionalized,MWNTs were linked with amino groups on its surface,7.46wt%EDA was grafted onto the surface of MWNTs,and the structure of the MWNTs-NH2 were only a little changed compared with MWNTs-COOH.The results of the effect of the preparation process on the properties of PA6-g-MWNTs composite fibers indicated that with increasing of the mass fraction of MWNTs-NH2,the breaking strength of PA6-g-MWNTs composite fibers increased firstly then decreased,the breaking elongation decreased;with increasing of the reaction time,both of the breaking strength and the breaking elongation of PA6-g-MWNTs composite fibers increased firstly then remain unchanged;with increasing of the spinning temperature,both of the breaking strength and the breaking elongation of PA6-g-MWNTs composite fibers increased firstly then decreased;with increasing of the winding speed,the draw ratio and temperature,the breaking strength of PA6-g-MWNTs composite fibers all increased,the breaking elongation all decreased.The results of the structure and properties of PA6-g-MWNTs composite fibers indicated that MWNTs in the composite fibers were winded and surrounded by PA6 macromolecular chain;PA6-g-MWNTs were prepared by A6-g-SMA and MWNTs-NH2 through an amidation reaction;the thermal decomposition temperature range of the composite fibers were 411.7??466.1 ?,and MWNTs content in the composite fibers was 1.37wt%;the crystal form of the composite fibers was fairly similar to PA6's,and the crystalline degree of the composite fibers was 67.73%;the breaking strength and breaking elongation of composite fibers were 6.59 cN/dtex and 24.32%.