相变过程对等规聚丙烯/炭黑复合材料中填料网络的影响

采用柔和混合方法制备出炭黑(CB)填充等规聚丙烯(iPP)复合材料,CB在iPP熔体中可以进行团聚而形成填料网络,采用动态流变-电阻同步测试的方法,研究原位结晶-熔融过程对所形成网络的影响.实验结果表明,经历原位结晶-熔融后复合材料中可以被动态流变实验检测到的填料网络消失,这是由于结晶和熔融过程中都会影响填料网络结构,而熔融过程中网络的破坏更为显著.相变后网络的重建过程说明,相变过程不能完全破坏熔体中形成的团聚结构,填料网络容易重新形成.

INFLUENCE OF PHASE TRANSITION ON THE FILLER NETWORK IN ISOTACTIC POLYPROPYLENE/CARBON BLACK COMPOSITES

The influence of phase transition on the filler network in the isotactic polypropylene/carbon black(iPP/CB)composite was studied.The combination of dynamic rheological and electrical measurements was used to monitor the evolution of the conductive resistivity and storage modulus of the composite during melt annealing and in situ crystallization and melting.In order to obtain a composite with a good filler dispersion state and with a strong tendency of filler aggregation,the mild blending method was used to fabricate the composite.An iPP/CB composite containing 6 wt% CB was used.The results suggest that the CB particles can aggregate and form a filler network in the composite during melt annealing,while the formed filler network could be affected by the phase transition(crystallization and melting) of the polymer matrix.In the crystallization process,the resistivity of the composite increases slightly,indicating that the growing lamellae can maneuver the filler particles and break some weak linkages in the filler network.In the melting process,the resistivity of the composite increases significantly,revealing the expansion of the polymer matrix leads to the significant breakdown of the filler network.After in situ crystallization and melting,the filler network which can be detected by the dynamic rheological experiment disappears,demonstrating that the phase transition breaks the filler network.The different developments of the storage modulus before and after phase transition show that the phase transition process cannot destroy all the aggregation structure which has formed in the previous melt annealing process.The filler network can be reconstructed quickly after in situ crystallization and melting.