Adriana Berenice Espinoza‐Martínez

This study investigates the effects of poly(lactic acid) (PLA), montmorillonite (MMT), and castor oil (CO) on the water vapor permeability (WVP) and tensile strength (TS) of poly(butylene adipate‐co‐terephthalate) (PBAT)/PLA films. A Box–Behnken experimental design is employed to generate experimental data for predictive modeling using response surface methodology (RSM) and artificial neural networks (ANN), validated using independent test samples. The ANN models exhibit superior predictive performance for both WVP and TS (correlation coefficient, R > 0.98), whereas the RSM model shows limited predictive accuracy for WVP ( R < 0.88). ANOVA and sensitivity analysis identify CO as the most influential factor affecting WVP, while PLA is the primary contributor to TS. Response surface analysis indicates that optimal WVP occurs at high CO (1.5 wt%) and intermediate MMT (1 wt%), whereas maximum TS requires high PLA (28.57 wt%) and MMT (1.5 wt%) with low CO (0.5 wt%), reflecting a trade‐off between barrier and mechanical reinforcement mechanisms. Furthermore, the ANN models are integrated as objective functions into a multi‐objective genetic algorithm (MOGA) to simultaneously maximize TS and minimize WVP, generating Pareto optimal solutions. These results demonstrate the effectiveness of combining RSM and ANN modeling with multi‐objective optimization for designing biodegradable packaging films with balanced barrier and mechanical properties.

Biodegradable packaging plastics combining good mechanical properties and low gas permeability is required to avoid environmental and food safety concerns. This study explores the impact of montmorillonite (MMT) and halloysite nanotubes (HNT), on the mechanical, optical, and oxygen permeability of blown film poly (butylene adipate‐co‐terephthalate) (PBAT) composites. The morphology of the films was evaluated by x‐ray diffraction (XRD), differential scanning calorimetry and scanning electron microscopy. Good distribution/dispersion of clays is found in the PBAT‐MMT films. Besides, there is an increase in the crystallinity of PBAT due to the nucleating effect of HNT. Improvement in the tensile strength and elongation at break in the machine direction is obtained up to a clay content of 1.5 vol%. The incorporation of 1.5 vol% of MMT and 1 vol% of HNT leads to a reduction in the oxygen permeability of the PBAT film by 29% and 38% respectively. Furthermore, the films remain transparent regardless of clay content. Finally, the feasibility of the films for food storage is tested in grapes, obtaining extended shelf life. The favorable mechanical, barrier and optical properties of the biodegradable films, along with the scalable production process, make them attractive for application in the storage and preservation of food products.

In recent years, alternatives have been sought for the reuse of lignocellulosic waste generated by agricultural and other industries because it is biodegradable and renewable. Lignocellulosic waste can be used for a wide variety of applications, depending on their composition and physical properties. In this chapter, we focus on the different treatments that are used for the extraction of natural cellulose fibers (chemical, physical, biological methods) for more sophisticated applications such as reinforcement in biocomposites. Due to the different morphologies that the cellulose can present, depending from sources, it is possible to obtain cellulose nanocrystals (CNCs), micro- nanofibrillated cellulose (MFC/NFC), and bacterial nanocellulose (BNC) with different applications in the industry. Among the different cellulose nanomaterials highlighted characteristics, we can find improved barrier properties for sound and moisture, the fact that they are environmentally friendly, increased tensile strength and decreased weight. These materials have the ability to replace metallic components, petroleum products, and nonrenewable materials. Potential applications of cellulose nanomaterials are present in the automotive, construction, aerospace industries, etc. Also, this chapter exhibits global market predictions of these new materials or products. In summary, lignocellulosic residues are a rich source of cellulose that can be extracted to obtain products with high value-added and eco-friendly characteristics.

Composite materials of polyethylene terephthalate with silanized halloysite nanoclay were prepared and characterized. Halloysite was first functionalized with benzoyloxypropyltrimethoxysilane and then incorporated it into the polymer matrix via melt extrusion at 0.5, 1, and 2 wt% clay load ratios. The modified clay was characterized by means of elemental carbon quantification, thermogravimetric analysis, X-ray diffraction, and nitrogen adsorption–desorption. The silanization was confirmed to have taken place with an approximate reaction yield of 5%. While the silanization did not significantly affect the crystal structure or the morphological properties of the clay, a mass loss starting from 190 °C attributed to the organosilane compound used to modify the clay was observed in the reacted samples, along with increased thermal stability. The composite materials exhibited an increase in Young’s modulus and a decrease in the ultimate strain, but not a significant change in the oxygen permeability of the composites with respect to the neat PET. Graphical abstract

A work was carried out in order to obtain a TPV based on HDPE and EPDM, studying the effect of three different peroxides. The effect of one mono- and two bifunctional peroxides was studied. In general, at equal wt% of peroxide, the bifunctional peroxides produced greater gel content, higher tensile stress, and higher elongation at break. Thereafter, the work was focused on studying the effect of this TPV, as well as a commercial TPO, on the tensile and flame retardant properties of composites based on blends of HDPE and a thermoplastic elastomer (either TPV or TPO), plus 130 phr of magnesium hydroxide (MH). The composites without the rubbery phase, but with 130 phr of MH, were highly brittle and fragile. The composites with the rubbery phase, on the other hand, (either TPO or TPV), were tougher and presented relatively much higher tensile properties. With regard to flame retardancy, the formulations containing the TPV showed better flame retardancy and passed as V-1 in the UL-94V. With respect to the cone calorimeter, those with TPO or TPV all generated a total of 80 MJ of heat energy. The compositions with TPV, however, generated this amount of heat over a larger period of time, i.e., showing less heat generated per second. In addition, the compositions with TPV presented a markedly lower pHRR, by an average of 15%. Thermogravimetric analysis (TGA) showed that the MH in the samples with a 40 wt% rubbery phase starts decomposing at 315°C. However, as the temperature increases, the MH in the TPV composite apparently decomposes at a slower rate than that in the TPO composite.

Nucleation mechanisms of poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), and poly(ethylene naphthalate) (PEN) on single‐wall carbon nanotubes (SWNTs) are proposed, based on experimental evidence, theoretical epitaxy analysis, and semiempirical quantum chemical calculations. In order to elucidate early nucleation stages polyester‐coated nanotubes were obtained from highly diluted solutions. High‐resolution transmission electron microscopy (HRTEM) revealed helical morphologies for PET/SWNTs and PEN/SWNTs and the formation of lobules with different orientations for PBT/SWNTs. To explain the morphological behavior one model was proposed based on crystallographic interactions, that is, epitaxy. Theoretical epitaxy calculations indicated that epitaxy is not possible from the strict epitaxy point of view. Instead, aromatic self‐assembly mechanism was proposed based on π‐π interactions and the chirality of the nanotube. It was proposed that the mechanism implies two steps to produce helical or lobular morphologies with different orientations. In the first step polymer chains were approached, aligned parallel to the nanotube axis and adsorbed due to electrostatic interactions and the flexibility of the molecule. However, due to π‐π interactions between the aromatic rings of the polymer and the nanotube, in the second step chains reoriented on the nanotube surface depending on the chirality of the nanotube. The mechanism was supported by semi‐empirical calculations.