Effect of maleic anhydride and oxygen functionalized carbon nanotube on polyamide 6 and polypropylene blend properties

This work aims to investigate how adding functionalized carbon nanotubes (CNTs) to a Polyamide 6/polypropylene blend influences its properties. CNT functionalization was carried on through plasma with oxygen (CNT_O2) or maleic anhydride (CNT_MA). CNT_O2 presented the highest amount of oxygen, but, as the treatment time in plasma was twice as long as that of the CNT_MA sample, the oxygenated groups, for the most part, tended to formed lactones. On the other hand, plasma treatment with maleic anhydride was more efficient to insert carboxylic groups onto the CNT surface. Adding non-functionalized CNT in the blend, an elongation of PP phase was observed. In the functionalized CNT nanocomposites, a significant decrease in phase size was observed. No improvement in adhesion between phases was observed. Crystallinity degree decreased when non-functionalized CNT was added and increased with functionalized CNT. Despite the greater interaction between amorphous and crystalline regions observed in nanocomposites with CNT_O2, the highest values of storage module came from CNT_MA nanocomposite. The COOH groups on the CNT surface reacted with the polyamide, improving tension transfer between phases and leading to a better performance in blend mechanical properties.