REACTIVE EXTRUSION OF ACRYLIC-ACID GRAFTED POLYPROPYLENE WITH HEXADECYLAMINE

To study the possibility of the production of branched polypropylene ( PP) by a reactive extrusion (REX) route, side chains were introduced o n the backbone of a polypropylene material by reacting hexadecylamine with acrylic acid grafted PP. Experiments were carried out both in sol ution and in the melt, and the products were analyzed by FTIR, element al analysis, dynamic mechanical, and rheological techniques. Analysis of the FTIR spectra of the samples produced in the solution reactions, at an equal molar ratio of [- NH2]/[-COOH] without catalyst addition and without removal of the by-product, revealed that the formation of imide was increased with increasing the reaction time up to 10 h, whil e a further increase in reaction time resulted in a reversal of the re action. In the REX experiments, FTIR analysis showed that the imide fo rmation increased with the [-NH2]/[-COOH] molar ratio. At a molar rati o of one, more imide was present in the REX product than the in-soluti on one. Elemental analysis suggested that the nitrogen content in the products initially increased with [-NH2]/[-COOH] molar ratio and then reached an almost constant value at molar ratio values of about unity. The glass transition temperature (T(g)) was measured by dynamic mecha nical analysis (DMA), and it was found that the attachment of the alky l chains caused a reduction in T(g) of the products. Finally, rheologi cal measurements showed that the shear viscosity of the products incre ased with the amine/carboxyl molar ratio at low shear rates and that t heir moduli were enhanced as a result of the attachment of the alkyl s ide chains.