STUDIES ON PHASE STRUCTURES AND PROPERTIES OF POLYPROPYLENE/POLYAMIDE 1010\ BLENDS BY ANALYSIS OF MICROSCOPE PHOTOGRAPHS

Abstract

The phase structure and morphology of the blends of polypropylene (PP)/polyamide (PA1010) and a part-compatibility system (PP/PA1010/PP-g-MAH) were analyzed by graph technique using scanning electron microscope (SEM) images.The structure parameters,such as the average diameter,d,average chord lengths,,and distance between mass centers,D,of the dispersed phase,in PP/PA1010 and PP/PA1010/PP-g-MAH blends were calculated.The morphology,as well as the relationship between the structure parameters and the compositions of the two blend systems was discussed.These results showed that the variation of structure parameters depended upon the compositions of blends.Simultaneously,the mechanical properties of the blends were measured.They depended on the compositions of the blends.For PP/PA1010 blends,the relationship between the modulus and the composition was complex.When the content of PP increased from 10% to 20%,the modulus increased and the numerical value of the modulus of the blends was greater than that of PA1010.The modulus reached a minimum when the content of PP varied from 20% to 70%.This was because a double-continuous phase appeared in this region.The modulus was constant and was close to that of PP when the content of PP was greater than 70%.However,when PP was the dispersed phase,the yield strength had a linear relationship with the content of PP.The yield strength decreased with the increase of the content of PP in blends.For PP/PA1010/PP-g-MAH blends,the modulus changed linearly with the variation of the content of PP because of the existence of compatibilizer.The modulus increased when the content of PP increased.The yield strength changed linearly with the content of PP in PP/PA1010/PP-g-MAH blends.The yield strength decreased with the increase of the content of PP when PP was the dispersed phase whereas the yield strength increased when PA1010 was the dispersed phase.The relationship between the mechanical properties and the structure parameters,such as the ratio of average chord lengths,_1/_2,was discussed.For PP/PA 1010,_1/_2,showed linear relationship with the mechanical properties of the blends.Moreover,this relationship obeyed the same rule as that of the relationship between mechanical properties and the content of PP.For PP/PA1010/PP-g-MAH blends,_1/_2 was also linearly related with mechanical properties.The modulus increased while the yield strength decreased with the increase of _1/_2.The studies on the relationship between the mechanical properties and the average diameter of thedispersed phase showed that this relationship was complex for PP/PA1010 blends.The circumstance was different when average diameter was less than 4 μm and greater than 10 μm.However,for PP/PA1010/PP-g-MAH blends,the mechanical properties were linearly related with the average diameter.Both the modulus and the yield strength decreased when the average diameter increased.The experimental results also indicated that the mechanical properties had a linear relationship with the distance of mass centre,D,for both blends.In both cases,the modulus and the yield strength decreased slowly with the increase of the average diameter.Generally speaking,the phase structure parameter has a certain relationship with the mechanical properties of the blends.