Hydrothermal Carbon as Reactive Fillers to Produce Sustainable Biocomposites with Aromatic Bio-Based Epoxy Resins

Abstract

Thiswork is focused on the development of sustainable biocomposites based on epoxy bioresin reinforced with a natural porous material (hydrochar, HC) that is the product of spruce bark wastes subjected to hydrothermal decomposition. To identify the influence of hydrochar as a reinforcing material on the designed composites, seven formulations were prepared and tested. An aromatic epoxy monomer derived from wood biomass was used to generate the polymeric matrix, and the formulations were prepared varying the filler concentration from 0 to 30 wt %. The reactivity of these formulations, together with the structural, thermal, and mechanical properties of bio-based resin and biocomposites, are investigated. Surprisingly, the reactivity study performed by differential scanning calorimetry (DSC) revealed that HC has a strong impact on polymerization, leading to an important increase in reaction enthalpy and to a decrease of temperature range. The Fourier Transform Infrared Spectroscopy (FT-IR) investigations confirmed the chemical bonding between the resin and the HC, while the dynamic mechanical analysis (DMA) showed increased values of crosslink density and of storage moduli in the biocomposites products compared to the neat bioresin. Thermogravimetric analysis (TGA) points out that the addition of hydrochar led to an improvement of the thermal stability of the biocomposites compared with the neat resorcinol diglycidyl ether (RDGE)-based resin (T5% = 337 °C) by ≈2–7 °C. Significantly, the biocomposites with 15–20 wt % hydrochar showed a higher stiffness value compared to neat epoxy resin, 92SD vs. 82SD, respectively.

Preparation and Properties of Hydrogels Based on Lignosulfonate and Its Efficiency of Drug Delivery

“…The results were showed in Figure 2. Briefly, the broad peaks at 1589 cm −1 and 1427 cm −1 were ascribed to benzene ring in LS, [19,20] and the absorption at 1119 cm −1 was assigned to C−O and C−H stretching where aliphatic ether was believed to have interactions with benzene ring structures [21] . The one centred at 1226 cm −1 was noticed for bending vibration of phenol hydroxyl groups, and 1049 cm −1 for S=O stretching.…”

Use of covalent dynamic networks as binders on epoxy‐based carbon fiber composites: Effect on properties, processing, and recyclability

“…Although in this research, the focus has been placed on the binder and its capacity to link together fiber and resin. It is important to consider all the components and research that surrounds the carbon fiber thermoset composites which are aiding the transition of CFRP toward the circular economy, 30 such as the development of bio‐based carbon fiber, 31,32 development of biobased epoxy resins 33 . And, research based on the optimization of recycling strategies: pyrolysis 34 and solvolysis 35 .…”

“…It is important to consider all the components and research that surrounds the carbon fiber thermoset composites which are aiding the transition of CFRP toward the circular economy, 30 such as the development of bio-based carbon fiber, 31,32 development of biobased epoxy resins. 33 And, research based on the optimization of recycling strategies: pyrolysis 34 and solvolysis. 35 The issue in all these cases in the inability to separate and treat properly the different components of the composite.…”

A Sustainable Approach on Spruce Bark Waste Valorization through Hydrothermal Conversion

“…This study is focused on spruce bark (Picea abies) decomposition through a hydrothermal process with the main goals: (i) to produce hydrochar from spruce bark (SB) wastes, (ii) to study the process and highlight the relevant influence of process parameters, (iii) to reveal the chemical, structural, and thermal characteristics of the HC in order to prove the use of this material as a reactive filler in composite design [53,54]. To the best of our knowledge, none of these aspects have been studied before.…”