The Effect Of The SMA-g-PA6 Architectures On The Formation Of Co-continuous Morphology In Reactive Compatibilized PS/PA6 Blends

All components of polymer blends with co-continuous morphology are continuous and penetrate into three-dimensional network.As to co-continuous polymer alloys,they can combine excellent properties of each component.What's more,there are quantities of potential applications in the fields of the preparation of porous materials,self-supporting materials and controlling drug delivery,and so on.Recently,as the inorganic nanoparticles has been investigating and developing,particularly great attentions has been paid on the study of graphene,compounding inorganic nanoparticles with polymer blends to obtain nanocomposites with outstanding properties(such as,electric conduction,thermal conduction,flame retardant,electromagnetic interference shield,and so forth)has attracted a lot of interests.Consequently,it is important that keep on investigating co-continuous morphology of polymer blends.Previously,an unique theory of compatibilising by dual compatibilizers had been put forward by our research group.The theory goes that the compatibilizer with high molecular weight trunk chain does favor to transfer stress and promote the minor phase to be stretched into fibroid structure,in the same time,it can stabilize these fibroid structures.On the orther hand,the other compatibilizer with low molecular weight trunk chain tends to form an interface with large radius of curvature,which does favor to promote minor phase to form fibroid structures on it.In this thesis,the immiscible system of polystyrene(PS)and nylon 6(PA6)had been selected as research object.And dual copolymers had been used as compatibilizers,namely,hSMA with large molecular weight trunk chains and lSMA with low molecular weight trunk chains.In our experiment,the molecular weight and content of maleic anhydride of lSMA have been fixed at Mw =1 1,500g/mol and 16wt%,respectively.Meanwhile,the molecular weight and content of maleic anhydride of hSMA have been changed.There are two type of hSMA used in our experiment,namely,hSMA-1 whose molecular weight is Mw = 250,000g/mol and content of maleic anhydride was 8wt%;hSMA-2,whose molecular weight is Mw=110,000g/mol and the content of maleic anhydride was 23wt%).The emphasis had been stressed on the effect of the architectures of the in-situ formed hSMA-g-PA6 on the stress transfer between to phases.In particular,when PA6 serves as matrix phase,the viscosity of bulk phase is relatively low,which does harm for transferring stress from PA6 matrix phase to PS minor phase.Consequently,increasing the content of maleic anhydride of hSMA can form hSMA-g-PA6 with more PA6 graft chains.These abundant PA6 graft chains stretch into PA6 matrix phase,which tremendously promote stress to transfer.Moreover,it can lead to the formation of co-continuous morphology.All kinds of experimental results show that PS/PA6 blends can gain co-continuous morphology only when PA6 serves as minor phase in the case that the dual compatibilizers are hSMA-1 ? lSMA.However,when the dual compatibilizers are hSMA-2?lSMA,the blends possess perfect co-continuous phase no matter which component serves as matrix phase.The co-continuous morphology obtained in our experiment only coarsens and remains co-continuous morphology after annealing for 25 min at 240 ?.However,no matter which method was used to get co-continuous morphology,it was unstable thermodynamically.As long as it underwent enough annealing,the co-continuous morphology would change into droplet-in-matrix morphology.In order to certify this view of point,the experiment of varying blending time had been carried out.In this section,the blending time was varied from 1.5min to 5.5min.Ii was shown that the perfect co-continuous morphology had been obtained only when the blending time was 2.5min.As the blending time increased,the co-continuous morphology gradually coarsened.Eventually,the co-continuous morphology would change into droplet-in-matrix morphology.Besides,the influence of several kinds of relevant experimental conditions on the morphology of PS/PA6 blends had been investigated.According to experimental results,the optimal process parameters for preparing PS/PA6 blends with co-continuous morphology had been verified.As we all know,the rotate speed was closely related to the shear strength which polymer blends went thorough during the process of compounding.The rotate speed was setting within the range from 80 rpm to 150rpm to study the effect of it on the morphology of PS/PA6 blends with component ratio of 70/30.In the light of the variation of torque,the result of selective solvent extraction and the SEM micrographs,a conclusion had been given that the minor phase(PA6)was stretched into fibroid structures rather than sea-island structure when the rotate speed was set at 105rpm.Subsequently,the content of hSMA was adjusted from 6.44wt%to 16.1wt%.By the means of selective solvent extraction and SEM,the results showed that the PA6 minor phase of all PS/PA6 blends had been stretched into fibroid structures among the range of content of hSMA.What's more,as the content of hSMA increased,the quantity of PA6 with fibroid structures increased,but the phase size increase as well.As a result,the content of hSMA was set at 6.44wt%because it made the polymer blend possess stretched PA6 phase and the phase size not large at this point.In addition,the component ratio of blends had a great effect on the morphology.In order to study this effect,the content of PA6 of PS/PA6 blends had been changed from 30wt%to 70wt%.By virtue of selective solvent extraction and SEM,it had been shown that PS/PA6 polymer blends with component ratio at 60/40 and 50/50 obtained perfect co-continuous morphology.Unfortunately,as to the system of uncompatibilized PS/PA6,a co-continuous morphology can be obtained as well.