Effect Of CaCO₃ Particles On The Mechanical Properties Of Polyvinyl Chloride

In this paper, the effect of CaCO3 particles on the mechanical properties ofPVC/CPE/CaCO3 blends was investigated by means of SEM, FTIR and testingmaterial mechanical properties. The results show that the particle size of CaCO3 andtheir surface treatment agent have very important influence on the impact strength ofthe blends. When the CaCO3 particles with 1.36μm average particle size weremodified by a compounded coupling agent (ON337+NDZ), the Charpy notchedimpact strength of the PVC/CPE/CaCO3(100/10/10) blends reaches to 46.3kJ/m2,which is 1.75 times than that of the PVC/CPE blend. When the CaCO3 particles with1.79μm and 2.24μm average particle size were modified by the compounded couplingagent (ON337+NDZ), the Charpy notched impact strength of this blends is 23.6 and25.1 kJ/m2, respectively, which are close to that of the PVC/CPE(100/10) blend.Meanwhile, it was found that the Charpy notched impact strength of the blends isobviously increased with the increase in the molecular weight of the chloridepolyethylene (CPE).Additionally, when the CaCO3 content is 40(phr), the Charpy notched impactstrength of the blends is obviously increased only with the increase of CPE and DOPcontent in the blends, which is reaches to 65.7 kJ/m2 in thePVC/CPE/DOP/CaCO3(100/15/10/40) blend.The rheometric test with Brabender systems shows that the processability of theblends is improved by the extra fine CaCO3 particles that were treated with thecompounded coupling agent (ON337+NDZ).The Charpy notched impact strength of PVC/CPE/CaCO3 blends is alsoinfluenced with the processing conditions. When the blends were prepared under 150℃ of milling temperature and 170℃ of molding temperature, the Charpy notchedimpact strength of the blends reached to the highest. iMoreover, it is found that the cooling shrinkage stress in the blend moldingprocess has very important influence on the Charpy notched impact strength ofPVC/CPE/CaCO3 blends. The Charpy notched impact strength of 10 mm thick testingbar of the blends, which were prepared in a higher cooling rate, is 4 to 5 times thanthat of 4 mm thick of one.