In this research, poly(lactic acid) (PLA) nanocomposites with multi-walled carbon nanotubes (MWCNT) were produced by extrusion, injection, and compression molding, focusing on electromagnetic shielding. Various amounts of carbon nanotubes (MWCNTs) were tested in PLA matrix, specifically ranging from 1 to 4 parts per hundred resin (phr). The resulting nanocomposites were analyzed before and after undergoing annealing heat treatment. It was observed that as the MWCNT content increased, the melt flow index of PLA decreased. This reduction indicates that the nanotubes were effectively accommodated into the PLA chain. The PLA/MWCNT (2 phr) formulation presented the greatest balance of properties, with potential for electromagnetic shielding application. Scanning electron microscopy (SEM) demonstrated that incorporating 2 phr of carbon nanotubes in PLA promoted good distribution, favoring high electrical conductivity and electromagnetic shielding between 20–22 dB (8.2–18 GHz), corresponding to approximately 99% attenuation. Furthermore, its properties, such as elastic modulus (3156 MPa), tensile strength (65.1 MPa), hardness (77.8 Shore D), and heat deflection temperature (55.3 °C), increased compared to pure PLA. After annealing, the PLA/MWCNT (2 phr) nanocomposite underwent a molecular reordering, resulting in an increased crystalline fraction, as confirmed by X-ray diffraction (XRD). However, the electrical conductivity maintained the same order of magnitude, while the electromagnetic shielding varied from 19.7 to 20 dB. The results indicate that these nanocomposites are promising for electromagnetic shielding applications and can be manufactured in the molten state.

In this paper, the crystallization, fusion, and activation energy (Ea) of PBT/TiO₂ were thoroughly evaluated using DSC. Increasing the rates shifted the peaks of melt crystallization to lower temperatures while the fusions were almost unaffected. TiO₂ hindered the melt crystallization of PBT and lower crystallization rates, i.e., CMAX and K’ were acquired, in general, the crystallinity degree (Xc) was 4% higher in PBT/TiO₂ which is in the marginal error. Pseudo-Avrami and Mo models were applied to evaluate the melt crystallization kinetics; both fitted the melt crystallization quite well; deviations were observed at the beginning and the crystallization end most due to the nucleation and spherulites impingement during the secondary crystallization. Ea was evaluated using the Friedman model, considering the values of Ea less energy has to be removed from PBT/TiO₂ when compared to PBT, specifically at 1% of TiO₂.

The impact of adding 1%, 3%, and 5% by mass of kaolin residue (KR) was investigated regarding the mechanical, thermomechanical, and morphological properties, as well as the non-isothermal crystallization and melting kinetics of poly(ε-caprolactone) (PCL). The processing to obtain the PCL/KR composites was carried out through extrusion in a twin-screw extruder, followed by injection molding. This study investigated the events of first melting, fusion crystallization, and second melting using differential scanning calorimetry (DSC), with heating rates ranging from 5 to 25 °C/min. Additionally, models for the expanded Prout–Tompkins equation (BNA), the nth-order reaction with m-power autocatalysis by product (Cnm), and the Sestak and Berggren equation (SB) were tested. The PCL/KR composites exhibited an increase in the elastic modulus and the heat deflection temperature (HDT) compared to the pure PCL. Furthermore, high ductility was observed, as evidenced by the impact strength and elongation at break. The good distribution of KR in the PCL matrix was confirmed by scanning electron microscopy (SEM), which contributed to a more efficient crystallization process. The increase in KR content in the PCL matrix shifted the crystallization sigmoids to higher temperatures, acting as a nucleating agent, which reduced the energy barriers and increased the crystallization temperature by up to 5 °C. The melting events did not show significant changes with the addition of the KR. The results are important for the plastics processing industry, mainly due to the opportunity to add value to the waste and use it as an additive.