Chain extension behavior and thermo-mechanical properties of polyamide 6 chemically modified with 1,1′-carbonyl-bis-caprolactam

Abstract

A chain-extender based on 1,1 0 -Carbonyl-Bis-Caprolactam (CBC) was melt compounded with a commercial Polyamide 6 (PA6) by using a twin screw extruder. Rheological, thermal, and mechanical tests were performed on the resulting materials to evaluate the chain extension capability of CBC. Rheological tests on the compounded pellets and relative viscosity measurements on solubilized samples evidenced an increase of the viscosity values with the chain-extender amount, while the opposite trend was determined increasing the high temperature residence time. Terminal group analysis confirmed the increase of the molecular weight with the CBC content and highlighted a preferential reactivity of the chain-extender with aminic end groups. Differential scanning calorimetry (DSC) tests showed how both melting and relative crystallinity of the up-graded samples decreased with the CBC amount. Elastic and yield properties of chain-extended PA6 were similar to those of neat PA6 grades at different molecular weight, while crystallinity drop due to chain extension was responsible of an increase of the strain at break values. POLYM. ENG. SCI., 54:158-165, 2014. ª

Chain extension of recycled PA6

“…The chain extenders slightly decreased the crystallinity of PA6 suggesting the packing of PA6 chains to form a crystal lattice is hindered by the chain extension and/or branching. Similar observations regarding the effect of chain extender on the crystallization behavior of polymers were previously reported . The recycled PA6 showed a lower T g than the virgin PA6 and this can be explained by the larger free volume of chain ends enabling higher segmental mobility .…”

“…Taking as a base line, 0.1 Hz frequency, we observe the following values of η *: 2584 Pa s for pPA6, 1321 Pa s for the rPA6, 1653 Pa s (25%increase) for rPA6/EPOX, and 4037 Pa s (306% increase) for rPA6/ANHY. Thus, Joncryl ® ADR 3400, the chain extender with the multiple anhydride functionalities, not only rebuilds rPA6, it actually extends it beyond the structure of the pristine pPA6, suggesting that only end‐to‐end coupling is happening, the amide functionality being the most reactive as observed by Bucella et al . Joncryl ® ADR 4300, the chain extender with the epoxy functionalities does rebuild rPA6 but not even back to the level of the pristine pPA6.…”

Controlled synthesis of crosslinked polyamide 6 using a bis-monomer derived from cyclized lysine

“…Following a different approach, one can add the use of caprolactam dimer, i.e. 1,1 0 -carbonyl-bis-caprolactam, as chain extender, improving in particular the strain at break of PA6 [29,30]. Recently, Mathias and co-workers proposed the synthesis of vinyl monomers from a-amino-ε-caprolactam for the preparation of new vinyl polymers and supramolecular assemblies [31].…”

Simple and feasible strategy to fabricate microcellular poly(butylene succinate) foams by chain extension and isothermal crystallization induction

“…In the foaming process, PBS samples with higher T c will crystallize earlier than other PBS samples during the cooling process. The formed micro‐spherocrystals in various PBS samples could be served as physical crosslinking points to increase the melt strength as well as the interface between crystalline region and amorphous region could be acted as the heterogeneous cell nucleation sites, which were beneficial to increase cell density and decrease cell size during their foaming process …”

“…On the one hand, the branching points in PBS/PE‐ g ‐GMA samples could be acted as the heterogeneous nucleation sites, which could promote PBS crystallization nucleation . On the other hand, the movement of molecular chains of various PBS samples into the crystal lattice was restricted by the existence of branching and/or micro crosslinking structures in PBS, which was adverse to its crystallization growth …”