Injection Overmolding of Virgin and Recycled PA6 Composites: Mechanical, Morphological, and Hygrothermal Characterization

ABSTRACT This research explores recycled polyamide (rPA6) from waste fishing nets as a matrix for UD PA6GF reinforced thermoplastics, compared with virgin PA6 (vPA6). Three glass fiber contents were evaluated for each matrix. Tensile testing revealed that unreinforced rPA6 was slightly harder than vPA6 (−3.7%) and that reinforced rPA6 composites exhibited higher modulus (+11% for first tape to +20% for second tape). Tensile strengths were reduced in rPA6‐based composites (−0.5% for first tape to −21% for third tape), while ductility decreased substantially (−84% to −53%). Moisture absorption tests revealed that vPA6 (10.20%) absorbed slightly more water than rPA6 (9.09%), reaching saturation on 61 days but with greater diffusion in rPA6 (7.85 × 10 −13 vs. 5.02 × 10 −13 m 2 /s). The volume of absorbed moisture is directly correlated with the composition of the group CONH of the polymer; in other words, with higher CONH/CH 2 group for the repeating subunit enhancing the solubility of water molecule. Fiber's addition accelerated the equilibrium moisture uptake (11.04% for vPA6GF, 10.34% for rPA6GF) and the saturation timespan to 54 days but lowered the diffusion coefficients to 1.96 × 10 −13 and 1.85 × 10 −13 m 2 /s, respectively. After 28 days of aging in water the mechanical properties of vPA6, rPA6, vPA6GF rPA6GF decreased by 83.46%, 82.44%, 44.91% and 52.39%, respectively. The results highlight the recycling effect on the hygroscopic and thermo‐mechanical behavior of reinforced PA6 and guide the design of tougher overmolded parts with longer service life.