Preparation And Properties Of Super Tough PA11/LLDPE Alloy Materials

PA 11 has excellent properties such as heat resistance,low water absorption and chemical resistance,and has been widely used in military,electronic and automotive industries.Although PA11 has incomparable advantages in performance compared with traditional macromolecule materials,the single PA 11 performance can not meet the further application in these fields.Plus,the high price of PA 11 material greatly limits the application field and depth of PA11.Therefore,toughening modification of PA11 has been an important direction of PA 11 modification in recent years.Firstly,LDPE and LLDPE were added into PA11,respectively,and toughened by melt blending extrusion.Comparing the mechanical properties of the two blends,it was found that LLDPE had better toughening effect on PA11.The optimum content of LLDPE was 10%.The impact strength and elongation at break reached 41.4KJ/m2 and 25.9%respectively.SEM images show that the dispersed phase particles of LLDPE/PA11 system are smaller and more uniform,and there is a typical "sea-island"structure.The storage modulus,loss modulus and complex viscosity of LLDPE/PA11 system increase obviously.The melt flow rate of the system will decrease slightly with the increase of LLDPE content.Secondly,PE-g-MAH was selected as compatibilizer,and the effect of Compatibilizer on the properties of LLDPE/PA 11 blends was investigated.The mechanical properties test showed that the toughness of PE-g-MAH was the highest when the content of PE-g-MAH was 8%.The impact strength and elongation at break were 51.4KJ/m2 and 80.4%respectively.SEM shows that the addition of PE-g-MAH makes the dispersed phase particles smaller and the interface blurred,which enhances the interfacial cohesion and improves the compatibility of the blend system.It shows that the acid anhydride group in PE-g-MAH reacts with the amide group in PA 11 to form chemical bonds and improve the compatibility of the blend system.The rheological properties test showed that when the addition of PE-g-MAH was 8%and 10%,the storage modulus and complex viscosity of the blends reached the maximum,and the melt flow rate decreased by about 20%.PEG-1000 and N-BBSA were selected as plasticizers to investigate the effect of plasticizers on the properties of LLDPE/PE-g-MAH/PA11 blends.Mechanical properties test showed that the toughness of PEG-1000 and N-BBSA was the best when the addition of PEG-1000 and N-BBSA was 2%and 5%,respectively.The impact strength and elongation at break were increased by 187%and 184%respectively,and the elongation at break was increased by 5.1 and 5.4 times,respectively.SEM images show that the addition of toughening agent makes the dispersed phase particles smaller and the interface between the two phases blurred,but the excessive addition of toughening agent makes the dispersed phase particles fall off easily.The melt flow rate diagram shows that the addition of PEG-1000 and N-BBSA increases the melt flow rate by 1.7 and 1.9 times.The rheological properties test showed that the complex viscosity of the blends decreased obviously with the addition of two plasticizers,which indicated that the addition of PEG-1000 and N-BBSA increased the lubrication between the molecules and reduced the entanglement between the molecular branches,thus reducing the complex viscosity of the blends.The results show that when the mass ratio of N-BBSA/LLDPE/PE-g-MAH/PA11 is 5/10/8/90,a super-tough and high fluidity PA 11 alloy material can be prepared.Its impact strength is 57.7 KJ/m2,elongation at break is 91.5%,MFR is 6.7 g/10 min.