The Research On Preparation And Properties Of Nylon 6/Graphene Composites

Nylon 6(PA6)is one of the most important engineering plastics,which nas huge production and wide applications.With the rapid development of science and technology,the pure PA6 which has some disadvantages with high water absorption,dimensional unstability and poor heat resistance has become increasingly unable to meet the various needs of industry.Therefore,it is necessary to study the modification of PA6 to find a better performance of engineering plastics.Graphene has excellent thermal conductivity,electrical conductivity and mechanical properties,But graphene is not compatible with the polymer matrix,so it is necessary to modify the surface of graphene by add specific functional groups to improve the surface properties of graphene,which increasing the dispersion of graphene in PA6 matrix.The paper respectively using stearic acid and silane coupling agent to modify graphene,the inorganic phase of surfactants link with graphene through hydrogen bonds,while the organic phase has chain entanglement with PA6 matrix,which improves the compatibility with PA6 and graphene to get excellent performance of composite materials.(1)Modified graphene by stearic acid and silane coupling agent respectively.Studying the influence of the type and dosage of modified agent on the properties of PA6/graphene composite materials through mechanical properties,thermal conductivity,scanning electron microscopy(SEM)and so on.Results shows that when mass ratio PA6/graphene=85/15,m(graphene):m(silane coupling agent)=100:8,the melt flow rate,tensile strength,flexural strength,impact strength and thermal conductivity coefficient of the composite increased by 80.1%,14.2%,11.5%,34.5%and 14.6%respectively.It states modifier helps to improve the compatibility between graphene and PA6.SEM indicates that the dispersion of modified graphene in the composite is well and interface fuzzy.(2)Use 8 phr silane coupling agent to modify graphene and prepare the composites by melt-blending.Studying the influence of different content of modified graphene on processing properties,mechanical properties,water absorption performance,thermal conductivity,thermal stability and the microstructure of composites.Study shows that,with the increasing content of graphene,conglomeration increases while the melt flow rate and mechanical properties of the composites decline,but due to hydrophobic surfaces and high thermal conductivity of the graphene descend the water absorption rate and increase the thermal conductivity coefficient.When the content of graphene is 20 wt%,the water absorption of the composite decrease by 84.2%and the thermal conductivity is 9.4 times compared with pure PA 6.Therefore,the addition of graphene improves the thermal stability of composites.By microscopic appearance analysis is visible,with the increasing content of modified graphene,composite occurs interface gap and reunions is obvious.(3)Found in chapter two,as modified graphene content increases,mechanical properties of PA6/graphene composite materials decreases,so chapter three propose use glass fiber reinforce mechanical properties of composite.Early experiments found that when glass fiber joined more than 20 wt%,PA6/graphene composite materials can not be processed,in order to meet the needs of large-scale industrial production,fixed glass fiber content 10 wt%in this chapter,study the effect of different content of modified graphene on comprehensive properties of composite.Results show that with the increasing content of graphene,the melt flow rate,tensile strength and impact strength of the composites all decrease,while bending strength becomes firstly increased and then decreased.When the content of graphene is 10 wt%,the flexural strength of composites is increased by 2.5%compared with composites not added modified graphene.Compared to the PA6/graphene composite which not added glass fiber,the addition of glass fiber can improve the mechanical properties.With the increasing modified graphene the water absorption rate decreases and the thermal conductivity coefficient increases,it is consistent with the conclusions of the chapter 2.The TG and DSC analysis show that increasing graphene content can plays a role in improving the thermal stability of the composite.SEM analysis shows that each component in the composite dispersed uniformly,and the glass fiber has embedded in composite,which playing an enhanced role.