Clay distribution and crystalline structure evolution in polyamide 6/montmorillonite composites prepared by activated anionic polymerization

Abstract

Nanostructured polymer composites (NPC) based on polyamide 6 (PA6) are prepared by activated anionic ring-opening polymerization (AAROP) of mixtures of e-caprolactam (ECL) and organically treated montmorillonite (o-MMT). The polymerization is performed in bulk, at 165 C, i.e., below the melting point of the resulting APA6, the reaction time being in the range of 10-15 min. The o-MMT content is varied in the 0.5-10% range. X-ray diffraction (XRD) and transmission electron microscopy (TEM) show that exfoliated NPC can be produced with clay loads of 0.5-1.0%. Larger clay amounts lead to various degrees of intercalation of the MMT layers. FT-IR imaging proves that all NPCs contain MMT aggregates with sizes in the 10-20 mm range. The formation of the matrix crystalline structure is followed directly by performing AAROP of an activated ECL/o-MMT blend in a synchrotron beamline. Irrespective of the o-MMT type and concentration, it is the a-PA6 that forms first and in larger amounts. The c-PA6 polymorph can be found in predominating amounts only after melting and recrystallization of the already produced polymer matrix.

Reactive microencapsulation of carbon allotropes in polyamide shell-core structures and their transformation in hybrid composites with tailored electrical properties

“…The viscometric average molecular weight M v of empty PAMC and PAMC loaded with 2% of CB are 33 700 and 37 500 g/mol, respectively. After compression molding of PAMC to plates the M v values remain unchanged being comparable to the M v of commercial granulated hydrolytic PA6 with M v = 37 200 g/mol and, at the same time, significantly lower than the anionic PA6 (M v = 88 500 g/mol) produced with the same initiator/activator system in the bulk at 165°C [43,44]. The higher M v in the latter case is because the bulk AAROP takes place at higher temperature, in the polar molten ECL and in strongly basic medium.…”

The reactive compatibilization effect of copolymer macroactivator for immiscible anionic polyamide 6/polystyrene blends via in situ polymerization

“…The pattern of the neat APA6 prepared under the same conditions is also presented for comparison. It can be seen that when the addition of IEM is less than 0.465 wt %, the peaks at about 20.3° and 23.9° which can be assigned to the (200) and (002) planes of the α‐phase formed between adjacent chains by van der Waals forces or H‐bonds are predominant, as is in the neat PA6 . When the addition of IEM is greater than or equal to 0.465 wt %, The peak around 21.4° which is characteristic of the γ‐phase [(200) and (101) planes] is observed .…”

Preparation and properties of polyamide‐6‐based thermoplastic laminate composites by a novel in‐mold polymerization technique

“…The activator C20 contains two preformed imide links C( O ) N C( O ), in the presence of which polymerization starts directly with the propagation reaction. The AAROP conditions, for example, composition of the catalytic system, reaction temperature, time duration of the NYRIM process, and cooling conditions, were optimized in previous studies toward the production of high‐molecular‐weight APA6 matrix with M v > 35,000 with an ECL conversion of 97–99% …”

“…It was established by many authors that the polymorph content of PA6 and the α/γ relationship were directly related to its mechanical behavior (Ref. and references therein).…”

“…The structure of DL is according to that given in Ref. . The structure of C20 is based on the current analyses.…”