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This study proposes that green composites using recycled plastic bags (PEr) extruded with pineapple fiber waste (PR) from a juice industry to increase pineapple’s economic value stimulate practices that prioritize recycling and development of new materials. PEr composites were prepared using PR as a filler, using different fiber loadings of 5, 10, and 15 wt%, and the use of a coupling agent, prepared via extrusion and injection molding. The samples were investigated by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis, inflammability, mechanical tests (tensile, impact, and shore hardness), scanning electron microscopy, and water absorption tests. FTIR results demonstrated that the addition of PR to the PEr caused a decrease in the characteristic bands of neat PEr, evidencing the chemical interactions. Thermal analysis showed that the addition PR decreased composites' thermal stability, causing relatively higher percentages of char compared to neat PEr, which increased the burning rate of composites, except for PEr/15PR and PEr/5PR-C. Green composites exhibited higher tensile modulus and hardness than PEr, but the impact tests presented a decrease in the fibers' addition to the PEr due to the reduction of toughness and resilience. SEM of fractured surface composites presented microcracks, voids, and fibers breakage in the interface. The composites showed low water absorption (up to 0.804%). The coupling agent’s use presented a low influence on the mechanical and thermal properties and a slight decrease in water absorption. These results demonstrate o potential of the reuse of plastic bags and industrial waste for green composites.

We developed polyurethane foams (PU) filled with eucalyptus charcoal residue (ECR) (5, 10, 20, and 30% by wt) for diesel sorption from seawater. The PU foams were characterized by FTIR, FT-Raman, SEM, density, TGA, contact angle, diesel S500 and S10 sorption, and recyclability. The ECR addition altered PU chemical structure, inducing new chemical bonds and probably altering cross-linking ability of the foams, as indicated by FTIR. FT-Raman spectra of PU-ECR foams showed shifts associated with filler dispersion and interaction with the matrix; besides, its addition decreased the foam pore size and density. The ECR addition did not significantly change the thermal behavior of PU foam and increased hydrophilicity in low ECR content and hydrophobicity in high ECR content samples. Experimental results showed adequate oil sorption capacity, and the optimal amount was 30% (by wt) ECR, which enhanced the diesel sorption from 4.1 and 5.9 g.g−1 to 9.6 and 8.8 g.g−1 for diesel S500 and S10, respectively. The Langmuir sorption isotherm was the best-fitting model to describe oil sorption. Reusability of the PU + 30% ECR was examined through 34 and 39 cycles for diesel S500 and S10, and about 50% of the initial sorption capacity remained at the end. The results indicated the success of developing a sustainable material and demonstrating feasibility in practical applications of PU-ECR foam for spilled oil removal from seawater or treatment of oily effluents.

This research describes the influence of fiber content from the banana peel waste used as a filler in castor oil polyurethane foam (PU), obtaining eco-sorbent for vegetal oil sorption. Biocomposite...

Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) is a biodegradable, biocompatible, and non-toxic biopolymer. The biopolymer properties can be improved using cellulosic-based materials, often derived from agro-industrial residues, and promoting reuse/re-significance of a by-product for bone tissue engineering applications. Biocomposites of PHBV filled with bleached fibers of palm residues (BFPR) (0–10 % wt/wt) for 3D-printing were prepared. The scaffolds were obtained by additive manufacturing (fused deposition modeling (FDM)). The samples were characterized by stereomicroscopy, SEM, TGA, nanohardness, wettability, FTIR, and biocompatibility. Biocomposites filaments revealed homogeneous diameters, suitable for FDM. Composite filaments had thermal stability at 100–250 °C (processing did not degrade the material). The -OH groups of cellulose (enhanced by bleaching treatment) BFPR added to PHBV had advantages: optimal cell viability, wettability improvement, and slight nanohardness increase. PHBV/BFPR1 % scaffolds had an interconnected porous structure with a pore size of ~900 µm and 60 % filling.

Macadamia is a nut widely used globally in food, personal hygiene products, and human health. After removing the nut, high amounts of the shell residual, which is an underutilized material with high economic interest. This work presents a sustainable alternative to revalorize the macadamia nutshell residues (MR) developing the green composites. Polypropylene (PP) composites were prepared using different MR content (5, 10, 15, 20, 25, and 30 wt%) as a filler. The samples were investigated by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis, scanning electron microscopy (SEM), mechanical tests (tensile and flexure) before and after water absorption tests, and Life Cycle Assessment (LCA). FTIR results indicated that the MR acted only by physical impediments, without chemical interactions between the filler and matrix. Thermal analysis showed a significant increase (~ 20 °C) in PP thermal stability after MR addition, probably due to the filler high lignin content, and SEM photomicrographs indicate that high MR contents resulted in little cracks and voids in the interface. However, the defects did not influence the mechanical performance, and the green composites showed superior elastic modulus (2401 MPa) than the pristine PP (1516 MPa) and similar tensile strength (~ 30 MPa), confirmed by the statistical analysis and corroborating with the theoretical percolation network (25 wt%). The composites showed low water absorption (up to 0.3%), reflecting in downward variations in the wet samples' mechanical behavior. It evidences the possibility to use these samples for water applications. LCA indicated that higher MR contents promoted lower environmental impacts than the classical handling of this residue, and the results indicated that 30 wt% MR is the better environmental option. However, the PP/MR-25% showed reduced environmental impacts and associated with other properties improvements, considered the better sample. This work shows the MR revalorization as a sustainable approach to expand green composites applications.

Fused deposition modeling (FDM) has been a widely applied technology as one of the most practical tools of additive manufacturing in terms of industry 4.0. Biopolymer filaments obtained by extrusion can be a promising material for scaffold manufacturing by FDM 3D printers. In this work, composite filaments of polyhydroxybutyrate-cohydroxyvalerate (PHBV) reinforced with ZrO2·nH2O particles were obtained (1–10% wt/wt.) and characterized aiming the production of scaffolds by FDM process. ZrO2·nH2O particles were prepared and mixed to the PHBV in a mini-extruder. The pristine PHBV and composite filaments (PHBV/ZrO2) were characterized by stereomicroscopy, scanning electron microscopy (particle analysis), thermogravimetric analysis (TGA and DSC), X-ray diffractometry, Fourier transformed infrared spectroscopy , Vickers microhardness test (HV), and relative density. The addition of ZrO2·nH2O particles altered the behavior of the PHBV matrix: increased the number of ZrO2·nH2O particles in the composite filament surface, enhanced the amorphous phase and the relative density. The PHBV/7.5%ZrO2 sample presented higher microhardness. It was possible to print the filaments by FDM and the appearance of the scaffolds obtained was a cylindrical structure with rounded inner pores, contributing to the future application in regenerative medicine.

This work prepared eco-friendly biocomposites of polyurethane (PU) and sheath palm residues, using castor oil as a polyol. PU composites filled with natural fibers were prepared at different loading rates: 0 to 20 wt.%. Results indicated that the sheath palm was hydrogen-bonded to PU chains and increased the foams' density. Pore size decreased with an increase in fiber content, from 256 to 116 µm. The fiber's addition improved the ductility of PU foams (compressive modulus from 4.74 to 0.26 MPa) and the foams' crystallinity index (from 5.4 to 15.4%). Compared to pristine PU, the composites showed high hydrophobicity (reaching 123° of contact angle for PU-15%) and thermal stability (Tonset from 96 to 96.3°), and high density (from 41 to 60 kg.m−3), making the developed composites an excellent option for environmental applications, such as oil removal and contaminant adsorption.

Australian palm residues are generated by palm heart industry in large quantities and are considered an underused material with a composition rich in lignocellulosic structures. This residue is generally utilized as briquettes for energy or sheep feed; however, few works investigate this residue as composite fillers. This work aimed to revalue Australian palm residues (PR) by preparing polypropylene composites through melt mixing, using different fiber contents (0, 5, 10, 20, and 30 wt%), and evaluate the statistical influence of fibers (residues) alkali treatment (MPR) in composites mechanical properties. PR and MPR were evaluated by FTIR, XRD, SEM, TGA, and composites were assessed using thermal and mechanical analysis, in which ANOVA statistical analysis was applied. The residues addition increased the mechanical properties and their treatment enhanced the stiffness of the composites compared to pristine PP. However, ANOVA demonstrated that at low residues contents, surface treatment does not increase fiber-matrix interactions effectively, then tensile properties were statistically similar to PP. Considering tensile properties, 20% MPR showed statistically distinct properties, with significative enhancements; no filler contents dependence was verified. Flexural properties were more sensitive to residue loading, and composites with 30% PR and MPR presented superior mechanical performance. This difference is associated with a higher sensitivity of tensile stress towards fiber-matrix interactions, which was improved with fiber treatment. Also, the residues content and treatment influenced the composites' thermal stability, with better results for PP-MPR. Results indicate that palm residue is an excellent filler for improving composites' thermal and mechanical properties, with a greener character.

Polymer nanocomposites are a promising area of research due to quite superior to the conventional composites. However, obtaining a homogeneous distribution of the nanoparticles in the matrix has been a great challenge. Standard processing techniques of nanocomposites are non-practical, requiring longer periods and can affect both mechanical and thermal properties of the final product. The thermokinectic mixer is an interesting alternative due to its high-speed rotation leading to a better dispersion of the nanoparticle without compromising the polymer properties. This paper reports for the first time a nanocomposite of high-density polyethylene (HDPE)/Al2O3 processed by the thermokinetic mixer. The addition of Al2O3 nanoparticle (0 to 4% wt) to the HDPE led to an increase in both the melting and crystallization temperature. It was also observed an improvement of the mechanical properties due to the increase in the crystallinity degree, which is a consequence of the multiple nucleation sites of Al2O3 nanoparticles. An optimal composition was obtained at 4% wt of Al2O3. Thus, the nanocomposites processed by the thermokinetic mixer demonstrated a significant enhancement of the mechanical and thermal properties.

Surface modification of palm fibers has been made by different methods. This work, cellulose fibers from palm were bleached and modified by zirconium oxychloride. Cellulose fibers were coated with ZrO2·nH2O particles with different amount of zirconium oxychloride in acidic medium in the presence of cellulose fibers using ammonium hydroxide as the precipitating agent. The coating of hydrous zirconium oxide on cellulose fibers was carried out by scanning electron microscopy, X-ray diffraction, themogravimetric analysis, attenuated total reflectance Fourier transform infrared spectroscopy and atomic emission spectrometry with inductively coupled plasma were also techniques used to characterize the materials. Dichromate ion was adsorbed on the Cell/ZrO2·nH2O by immersing this solid in an aqueous solution of potassium dichromate. The analyses to determine the concentration after the adsorption were made using UV–Vis spectrum, in a wavelength of 349 nm. The results were satisfactory showing that the Cell/ZrO2·nH2O materials obtained presented good adsorption capacity. Results showed that the amount ZrO2·nH2O particles coated on cellulose fibers influenced in the sorption capacity of dichromate ions.

Continuous advances in 3D printing technology, associated with the development of sustainable materials, have driven the manufacture of new biofilaments compatible with numerous applications, such as automotive, robotics, food, and biomedical. In this work, sustainable filaments of PHB and PHBV filled with 5 wt% of pullulan were prepared, and its chemical, thermal, and morphological properties, crystallinity, 3D printing capability, and cytotoxicity were evaluated. Two PHBV samples were compared with different valerate concentrations: 6 and 8 wt%. Raman and FTIR results indicated that pullulan altered the polymeric chain organization, impacting the polymer crystallinity as corroborated by DSC analysis. The composites showed higher heat resistance in the range of 5–30% of mass loss, and all samples showed adequate thermal stability for fused deposition modeling (FDM) processing. pullulan increased the PHB and PHBVs crystallinity due to the nucleation effect and shifted melting temperatures to lower temperatures due to the dispersed phase/matrix interface. While PHB composites showed an irregular surface with large agglomerates, PHBVs composites showed good dispersion and filler/matrix interaction, which slightly impacted the filaments diameters, but classified these materials as a potential for 3D filaments printing. PHBV filaments were printed into biomedical scaffolds, and the results indicated the influence of valerate and filler dispersion, in which 8 wt% valerate is the adequate concentration for 3D printing. The printed scaffolds represent a novel biocomposite to the tissue regeneration field, confirmed by the cell viability values above 80%, being appropriate for biomedical and other 3D printing applications.

This work aimed to prepare surfactant modified-PBAT (poly(butylene adipate-co-terephthalate)) sheets with superior properties to increase the PBAT applicability and be a possible solution for plastic disposal environmental problems. Three different surfactant contents (0, 1, 5, and 10 wt%) were investigated, and their effects on PBAT chemical structure, mechanical and morphological properties, wettability, and water absorption were investigated. Modified-PBAT samples showed high hydrogen bond coefficients (0.57) than the pristine PBAT (0.54), indicating an excellent electrostatic interaction between both components and the formation of a rigid hydrogen-bonded network, as confirmed by mechanical tests, where the elastic modulus values for PBAT and PBAT+10% surfactant were 44 and 60 MPa. SEM images and roughness measurements showed changes in PBAT morphology after surfactant addition, improving the roughness and wettability by the voids and polar groups presence, altering the water absorption (WA) behavior. The higher water affinity resulted in high water absorption for PBAT-10%S (17%) compared to the pristine PBAT (2%), which improves hydrolysis tendency, which is the initial step to biodegradation. Biodegradation results indicated that the roughness and WA behavior influenced the biodegradation rate, facilitating hydrolysis and microbial attack, and accelerating modified samples weight loss. Our results suggested developing a material with superior mechanical properties, mainly for PBAT-10%S, that can be applied in several applications, such as packaging and furniture. After discharge, it is not an environmental problem, being a biodegradable material with a green character.

In this work, we prepared PU-composites with Australian palm residues (PR) in different contents (5, 10, 15, and 20 wt%) and granulometry (28 and 35 mesh) to improve the oil (crude oil and S500 Diesel) sorption capacity. The foams were characterized by life cycle assessment (LCA), scanning electron microscopy, oil sorption, desorption, and Langmuir, Freundlich, and Temkin sorption isotherms. LCA indicated that higher PR contents decreased the foam environmental impacts than the classical residue handling, indicating that 20 wt% PR is the better environmental option, independent of the residues granulometry. The PR incorporation into PU foams resulted in smaller pore sizes, with a higher number of homogeneous open-cells. The PU composites exhibited higher oil adsorption capacity than the pristine foam. The PU sample showed maximum absorption capability of 6.1 and 6.7 g g−1 for diesel S500 and crude oil, and the composites showed increased values of ∼18 g g−1 and ∼24 g g−1. The Langmuir model presented the best fit and predicted a maximum adsorption capacity of 30.39 and 25.57 g g−1 for PU-20% PR 28 and 35 mesh, respectively. The composites presented excellent reusability with PU-20% PR (28 mesh) and PU-20% PR (35 mesh), showing removal efficiency after 16 and 9 cycles, respectively. The results classify the developed foams as excellent materials to sorb spilled crude oil in marine accidents.

This chapter is focused on the development of palm fiber reinforced polypropylene (PP) composites by using thermokinetic mixer followed by injection molding. The effect of concentration (5 wt%) of coupling agent, Epolene (MA-g-PP) and pre-treatment with alkaline solution (10% w/v) was studied in details on palm fiber reinforced PP composites. Mechanical testing (tension and flexural) was carried out to determine the effect of fiber contents, treatment and compatibilizer. The chemical, physical and morphological properties of the fibers were examined by SEM, chemical composition, XRD and FTIR. The results showed that compatibilized composites have increased stiffness due to enhanced interfacial adhesion between the fibers and the matrix, as well as better homogeneity (better fiber dispersion) due to chemical bonding.