Study On The Preparation, Morphology And Properties Of PA6/K Resin Blend

In this paper, the grafted copolymer Kresin-g-MAH, a new toughening agent for PA6, was prepared by twin-screw-extrusion machine. K-MAH was studied as a toughening agent for PA6 and as a compatilizer for PA6/Kresin blend. Infrared (FITR)> Molau experiment scanning electron microscopy (SEM)^ differential scanning calorimetry(DSC)> dynamic mechanical thermal analysis (DMTA) and the impact testing were used in my study. The structure of K-MAH was researched, the FITR spectragram indicated that MAH has been grafed on K rensin because there was a special peak (1779cm'1) of MAH on FITR spectragram of K-MAH .In K-MAH, it was confirmed that the MAH was about 0.54wt% by chemical titration. Molau experiment showed that in the solution of formic acid of PA6/Kresin blend, some of the blend were not dissolved , there were two layers and the interface was very clear. However, in the solutions of PA6/K-MAH blend and PA6/K-MAH/Kresin blend, all the blends were dissolved, the solutions were very turbid, the interface was too dim to divide. So we can come to a conclusion that K-MAH not only has a good compatibility with PA6, but also can improve the compatibility of PA6/Kresin blend. The morphology of blends has been studied by SEM, the SEM figures showed that the disperse phase of K resin in PA6/Kresin blend was large and not average, but in the blend of PA6/K-MAH, the K-MAH phase was very average and small. We can see clearly that there was a grave deformation on the surface of crack face .In the blend of PA6/K-MAH/Kresin, we found that the phase of K resin became smaller than in PA6/Kresin blend. The DSC data indicated that when K-MAH was acceded into PA6, the temperature of melting (Tm), the percent of crystal (Xc) and the temperature of crystallize peak (Tc) of PA6 decreased. The glass translation temperature (Tg) of PA6 and K-MAH in PA6/K-MAH were anear each other. The mechanism properties of blends were researched especially. The results demonstrated that the impact strength of PA6 in dry condition or in dry and low temperature condition increased with the increasing of K-MAH content, when K-MAH content reached to 5wt%, the impact strength of blend improved, however, the yield strength and flexural strength changed a little. The blend had good properties when K-MAH content reached to 20wt%. There was a great influence on the MFR of PA6 when K-MAH toughened PA6. In my study, there was a better effect for PA6 with a low MFR than with a high MFR. To PA6, which MFR was 0.335g/10min, when K-MAH got to 20wt% in PA6/K-MAH blend, the impact strength of blend got to 161.9 kJ/m , which was as 14.6 times as pure PA6 in dry condition; the impact strength of blend got to 46.3 kJ/m2, which was as 4.3 times as pure PA6 in dry and low temperature condition, however, the yield strength and flexural strength only decreased 17.9% and 14.8% respectively. DMTA data showed that in dry condition the tan 8 peaks of PA6 and Kresin were anear each other. Store modulus of blend had a little change with the increasing of K-MAH , but the loss modulus was larger than pure PA6 when K-MAH was acceded into PA6 below room temperature, it showed that the material should make a large distortion in the interior of material and a part of energy translate into heat, when exterior power acted on the blend. The studying demonstrated that the MFR and the property of heat-resistent of blends all descended with the increasing of K-MAH. The water absorbability had a similar relation with K-MAH content: X=AXK-MAH+BXPA6 X: the water absorbability in blend, XK-mah: the water absorbability in K-MAH, XPA6: the water absorbability in PA6, A: percent of K-MAH in blend ,B:percent of PA6 in blend.