The Relationship Between Mechanical Properties And Interfacial Strength Of PP And POE In PP/POE Blends

The huge market of plastics has played an important role in promoting social development.Plastics are used in a wide range of applications including packaging,agriculture,construction,and automotive.Plastics,one of the pillar industries of the light industry,also have many shortcomings that limit their use.Whether it is general-purpose plastics or engineering plastics,although its strength is high,but the notched impact strength is low that can not meet the conditions of use in engineering.Toughening of plastics with rubber is a most simplest and effective way for a long time to deal with the defects of plastic in use.In the research process of long-term rubber toughened plastic system,the toughening theory is enriched.There is a contradiction in the rubber-plastic blending system:the rubber properties are changed while the rubber particle size is controlled.In order to control the particle size of the rubber,the metal coordination bond is introduced into the rubber,and the coordination bond can be broken during the rubber stress that can improve the tensile properties of the rubber,and the metal coordination bond can also open under high temperature conditions.The opening does not affect the processing fluidity,so that the modified rubber can maintain the same particle size as the unmodified rubber in the matrix,so as to discuss the effect of rubber properties on the mechanical properties of polymer blends under the condition of constant rubber particle size.In this paper,PP/POE was used as the research system.Tetravinylpyridine(4-VP)was grafted onto POE to prepare POE-g-VP,and then added zinc chloride(Zn Cl₂)in the POE-g-VP molecular chain.The metal coordination bond is formed.POE,POE-g-VP,POE-g-VP/Zn Cl₂were blended with PP respectively.The tensile yield strength of the three blended alloys was found without improvement.Since the residual free radicalsexist in POE-g-VP(grafting time is 5 minutes),the grafting reaction between the PP molecular chain and the POE-g-VP molecular chain can be initiated,resulting in an increase in the strength of the interface.The deformation of the dispersed phase particles is larger.The grafting time was extended to 30 minutes.The tensile strength of POE-g-VP₃₀(grafting time was 30 min)was the same as that of POE-g-VP.At this time,the impact strength of PP/POE-g-VP₃₀blend was reduced obviously,meanwhile,the impact cross section of the alloys has a small phase deformation variable.The improvement of the interface strength is more obvious for the impact strength of the polymer blends.The particle size distribution of the dispersed phase of the quenched section of all the blended alloys was observed by SEM to be 1.3±0.5um.Under the premise of the rubber particle size and the strength of the interface are same,the tensile yield strength of the blended alloy is not significantly improved by increasing the tensile strength of the rubber;under the same conditions of the dispersed phase particle size and rubber tensile properties,Increasing the strength of the two-phase interface The impact strength of the blended alloy is significantly improved.In order to further study the effect of the improvement of the interfacial strength on the impact strength of the blend,the interfacial strength of the rubber-plastic blending system was regulated by metal coordination bonds.The 4-VP was grafted onto PP molecular chain,and then the masterbatch A(PP-g-VP/POE-g-VP)and the masterbatch B containing,0.25mol of Zn Cl₂(PP-g-VP/POE-g-VP/Zn Cl₂),0.5mol Zn Cl₂masterbatchC(PP-g-VP/POE-g-VP/Zn Cl₂)were prepared.And due to the steric hindrance effect,Zn Cl₂has no complete conjugated action when adding 0.25mol Zn Cl₂.When it is 0.5mol,it can ensure that the grafted 4-VP is completely involved in the coordination,thereby changing the interface strength.The masterbatch and POE were blended with PP according to different ratios.It was found that the impact strength of PP/POE alloy was increased by 80%,102%and167%,respectively,when the masterbatch A,B and C was all 6wt%.Rheological tests show that the interfacial strength of the blend increases with the increase of ZnCl₂ content,and the impact strength of the blend increases with the increase of interfacial strength.The rheological test proves the interface strength of the blends,and the higher the interface strength,the higher the impact strength of the blends.Due to the serious degradation of PP during grafting,the performance cannot be further improved.No matter how the interfacial strength between the two phases is changed,the tensile yield strength of the blend is not effectively improved,which is similar to the above experimental results.