Development of Copolyamide-66/6 Cross-Linked Foams by a One-Step Reactive Extrusion Process

Abstract

The simultaneous chemical cross-linking and foaming of aliphatic copolyamide by one-step reactive extrusion using a bifunctional trialkoxysilaneimidazoline additive is studied. The aim was to reach efficient melt strength enhancing the cell growth without coalescence. From liquid NMR analyses, the cross-linked foam synthesis was evidenced resulting from both imidazoline ring opening (further reacting with the polyamide carboxylic acid endgroups) and alkoxysilane hydrolysis−condensation reactions (leading to cross-linking reaction and ethanol formation). From these chemical modifications, ethanol concomitantly released lead to the expansion of the cross-linked copolyamide. From the knowledge of this chemical mechanism, various extruder and formulation parameters have been modified and their impact scrutinized to optimize the foam morphology. With our optimized conditions, it was possible to synthesize rigid foam with mean pore size mainly below 90 μm and a density around 0.36 kg•m −3 while reaching reasonable compression properties (normalized modulus at 330 MPa). The maximum cell density obtained was 3 × 10 5 cells•cm −3 .

Biomass Thermoplastic (Co)polyamide Elastomers Synthesized from a Fatty Dimer Acid: a Sustainable Route toward a New Era of Uniform and Bimodal Foams

“…The 1 H NMR spectra traces, see Figures 1 & 2, were performed to ascertain the chemical structure of DFA-BDA X HMDA Y and DFA-BDA X HMDA Y (co)polyamides. 42 In the 1 3B and D). Generally, the amide groups of the PAs favor the formation of a H−bond while the introduction of shorter chain length diamines (EDA or BDA).…”

“…The M n , M w, and PDI of the PAs were determined by employing GPC. The M n , monomer feed ratio, and acid/amine values are also determined by 1 H NMR spectra and the data are summarized in Tables S2 and S3. It can be seen from Table S3 that the M w of the DFA-EDA X HMDA Y and DFA-BDA X HMDA Y range from 14,007 to 34, 243 g/mol and from 39, 533 to 44,191 g/mol.…”

“…The synthesis and dispensation of polymer foam materials have accelerated considerably since the mid of 20th century as the weight ratio/performance of the polymer is a virtue compromise for numerous applications. Demands of polymer foams were rapidly augmented owing to their large spectrum of benefits such as ease of design in diverse shapes, lightweight, high expansion rate, dielectric properties, thermal resistance, structural performance, and so forth . Hence, they are vastly deployed in daily lives, that is, aerospace, shoe midsoles, transportation, packaging, construction, furniture, electronics, automobiles, and biomedical materials. , Foamed polymer materials have become essential in current everyday life.…”

Thermoplastic matrix‐based composites produced by resin transfer molding: A review

“…Numerous copolymers have been studied in recent years, and their syntheses are well known, for example, lactam‐lactam, [ 87 ] lactam‐lactone, [ 88 ] and lactone‐lactone. [ 89 ] The production of copolyamides via manufacturing processes such as reactive extrusion [ 90 ] and casting [ 91 ] has also been reported in literature. To date, only one academic study has been reported on using copolymers as a matrix for the production of composites via TP‐RTM.…”

Lightweight, Highly Efficient, and Recyclable Absorption-Dominated Electromagnetic Interference Shielding Foams Based on Molecularly Designed Polyamide Elastomer/Carbon Nanotube Nanocomposites

“…9−11 However, traditional polyamide materials have a strong tendency to crystallize, which result in insufficient melt strength during high melting, thus seriously hindering the effective use of sc-CO 2 foaming in such systems. 12,13 Multiple methods, such as filler insertion, 14,15 chain extension, 16,17 and reactive crosslinking, 18 have been proposed to enhance the sc-CO 2 foaming performance of polyamides. However, despite effectively improving the properties of foaming materials, strategies involving the introduction of fillers or additives are often associated with process cost and dispersion problems.…”