A New Strategy for the Use of Post-Processing Vacuum Bags from Aerospace Supplies: Nucleating Agent to LLDPE Phase in PA6/LLDPE Blends

Abstract

In the aerospace industry, many composite parts are manufactured by processes using plastic vacuum bags made of polyamide 6 (PA6) as a consumable material. This implies that after demolding the part, this plastic material should be discarded, generating a considerable amount of waste. Tons of vacuum bags are discarded and incinerated per month by several companies in this sector, which highlights the need to recycle and/or reuse this material. PA6/linear low-density polyethylene (LLDPE) blends are of great technological interest because they can combine the excellent thermo-mechanical and oxygen barrier properties of the PA6 with high impact strength, good processability, and low cost of LLDPE. The replacement of neat PA6 by the post-processing vacuum bags residue PA6 may be a new strategy for the recycling of this material. In this work, PA6/LLDPE/maleic anhydride-grafted LLDPE (LLDPE-g-MA) (90/5/5) blends were prepared using a co-rotational twin-screw extruder and the neat PA6 was replaced by different contents of post-processing PA6 (5, 10, 15 and 20 wt.%). The mechanical, thermal, and morphological characterization was evaluated. The increase in the content of post-processing PA6 caused an increase in the crystallinity degree of the LLDPE phase, acting as a nucleating agent to the LLDPE phase, reducing the toughening effect of this phase in the blends and, therefore, providing this phase to act as a reinforcing agent.

Correlation of structure, rheological, thermal, mechanical, and optical properties in Low Density Polyethylene/Linear Low Density Polyethylene blends in the presence of recycled Low Density Polyethylene and Linear Low Density Polyethylene

“…The fact that no other characteristic peaks were visible in the spectra confirmed the purity of recycled material, indicating that no other chemical reaction has occurred during the recycling process and no contamination exists inside the material. 39,40 T A B L E 1 The blown film compositions. These parameters include temperature, shear, and oxidation levels, leading to competitive and simultaneous chain scission and crosslinking phenomena.…”

Recent advances in the use of Polyamide-based materials for the automotive industry

“…According to the authors, it was possible to verify the feasibility of recycling end-of-life multi-material polymeric products to replace neat polymers such as PU. The study by Souza et al [93] used vacuum bags of PA6 discarded after the curing process in an autoclave in the aerospace sector to produce PA6/LLDPE (linear low-density polyethylene) blends. According to the authors, this process demonstrated a new strategy for PA6 recycling, contributing to the reduction of waste from the aerospace industry.…”

Recycling of carbon fiber-reinforced thermoplastic and thermoset composites: A review

“…8,9 The growing demand for high-performance materials combined with the reduction of CO 2 emissions and, consequently, the need to reduce the structural weight of vehicles caused the global CFRP market to present annual growth of 6%. It was estimated that in 2025 the annual consumption would reach $27 billion, 10,11 already estimating a drop in 2020 and 2021 due to the global economic recession led by the pandemic (COVID- 19). This means, consequently, an increase in the demand for carbon fiber (CF) of approximately $2.8 billion by 2025 to obtain the CFRP and estimated demand of approximately 194 kt for CFRP in 2022.…”

“…In this case, it can be cited the reuse and recycling to reduce the disposal of waste destined for landfills and/or incineration, such as prepreg scraps, 15,16 protective prepreg packages, 17,18 and post-processing vacuum bags. 19 In addition to generating tailings from the production system, product residues, after their useful life, such as aircraft and automobiles, need to be properly disposed of. [20][21][22] In the aerospace sector, it is estimated that by 2050 all companies and suppliers will propose a system aimed at the reuse, remanufacturing, and recycling of their products at their Endof-Life (EoL) through the development of economically sustainable techniques and disposal management for CFRPs to obtain a circular economy.…”

“…In this case, it can be cited the reuse and recycling to reduce the disposal of waste destined for landfills and/or incineration, such as prepreg scraps, 15,16 protective prepreg packages, 17,18 and post-processing vacuum bags. 19…”