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

Abstract

In this work, a method for preparation of polyamide-6 (PA6) based laminates reinforced by glass fiber-(GFL) or polyamide-66 (PA66) textile structures (PL) via reactive injection molding is disclosed. It is based on in-mold anionic polymerization of e-caprolactam carried out at 165 C in the presence of the respective reinforcements performed in newly developed prototype equipment whose design concept and operation are described. Both composite types were produced for reaction times of 20 min, with conversion degrees of 97-99%. Initial mechanical tests in tension of GFL samples displayed almost twofold increase of the Young's modulus and stress at break values when compared with the neat anionic PA6. The improvement was proportional to the volume fraction V f of glass fiber fabric that was varied in the 0.16-0.25 range. A 300% growth of the impact strength was registered in PL composites with V f of PA66 textile of 0.1. Removing the surface finish of the latter was found to be a factor for improving the adhesion at the matrix-fiber interface. The mechanical behavior of GFL and PL composites was discussed in conjunction with the morphology of the samples studied by optical and electron microscopy and the matrix crystalline structure as revealed by synchrotron X-ray diffraction.

Polymers and Related Composites via Anionic Ring-Opening Polymerization of Lactams: Recent Developments and Future Trends

“…This was attributed to the following effects: (i) impeded movement of CL toward the growth center within the reinforcing textile, and (ii) presence of H 2 O and –COOH groups on the PA-6 reinforcement surface which consumes –NCO groups of the activator used. Dencheva et al manufactured PA-6 matrix based SPCs using PA-6 monofilament [ 193 ] and PA-6,6 textile [ 194 ] reinforcement, respectively. The content of the PA-6 fibers and PA-6,6 textile (plain weave), namely <20 wt % at <15 wt %, respectively, was quite low.…”

“…To study the effect of sizing, they were removed by washing with acetone. The AROP of CL was performed between 160 and 170 °C [ 193 ] or at constant 165 °C [ 194 ]. The CL conversion measured was in the range 97%–99% and the M v of the final PA-6 was ≥35 kDa.…”

Anionic Polymerization of ε-Caprolactam under the Influence of Water: 2. Kinetic Model

“…The most commonly investigated reactive thermoplastic material is anionic polyamide 6 (aPA6). The advantages of aPA6 are its low viscosity during processing [1,2] and good material properties due to its high crystallinity and high molecular weight [3][4][5].…”

Dually reinforced all-polyamide laminate composites via microencapsulation strategy

“…Recently, PA6‐based laminate composites reinforced by glass fiber and PA66 textile structures were obtained by means of reaction injection molding (RIM) via in situ AAROP of ECL employing prototype equipment with a mold of constant thickness . The tensile strength and Young modulus values of the glass fiber laminates with volume fractions of reinforcements up to 0.27, as well as the impact strengths were found to be with up to 300% higher than the neat anionic PA6 produced at the same conditions.…”