Redefining polyamide property profiles via renewable long-chain aliphatic segments: Towards impact resistance and low water absorption

Abstract

A series of renewable, long-chain, fatty acid-derived polyamides (PA) ranging from PA 6,14 to PA 6,18 were synthesized via polycondensation, yielding very high molecular weights and a remarkable property profile distinct from short-chain commercial grades. Most notably, synthesized polyamides exhibited good impact resistance, excellent stiffness-to-toughness balance and very low water absorption yet high oxygen and water vapour permeability; with this property profile being exemplified by PA 6,18. The increased repeating unit length and reduced number of amide linkages able to participate in interchain hydrogen bonding imparted a strong influence on material properties. The data highlights the benefits and technical advantages of utilising long-chain polyamides, while also significantly expanding the repertoire, knowledge and property profile of the long-chain aliphatic polyamide family, and providing a basis for further development of polyamides from renewable sources.

Optically transparent bio‐based polyamides with microcellular foaming properties derived from renewable difunctional aminoamides

“…The NH bond density of the PA chain reduced with an augment in alkylene chain lengths, consequently in a debilitate of intermolecular H‐bonding; therefore, T m and T c values of bio‐based PAs decreased with an increase in the length of alkylene carbon chains (Figure 6c,d). These results were in full agreement with the findings reported by Nguyen et al 39 and Kolb et al 47 All integrated bio‐based PAs showed clear T m and T c peaks screening their semicrystalline like structure. Like the DAA monomer, this behavior was believed to be triggered by the H‐bonding interaction created chiefly amid the DAA monomers.…”

“…So their IV is also increased with the increase of DAA chain length. This points out the correlation between polymerization reaction time and the degree of polymerization 25,39 …”

“…This was in unambiguous contrast to the decrease in T m and T c values. Despite this contradiction, an increase in X C% with increasing methylene unit length has been reported by both Nguyen et al 39 and Pagacz et al 45 …”

Highly Stretchable Fully Biomass Autonomic Self-Healing Polyamide Elastomers and Their Foam for Selective Oil Absorption

“…Figure 9a displays the percentage of water uptake of PA36,IA and PA36,36 after being submerged in water for 24 h compared with other PAs reported in previous literature [51]. PA36,IA displays a water absorption value of 0.2%, and PA36,36 displays water absorption of zero percent after 24 h of water submersion, representing hydrophobicity.…”

“…The T g of PA is associated with the monomers' chain length and the amide group concentration in the polymer chains. Therefore, longer monomer chains result in greater mobility of PA36,36, meaning it is much softer [50], so the synthesized bio-based PAs possess much lower T g values than the traditional rigid PAs, i.e., PA11 (T g = 68 • C), PA6,6 (T g = 80 • C), and PA6 (T g = 78 • C) [51]. Due to the existence of a rigid pyrrolidone ring in PA36,IA, it exhibits a higher storage modulus value than PA36,36.…”