Cost-effective strategies for integrating bio-oil production with biochar utilization in new sustainable platforms are needed to improve the economic viability of pyrolysis for energy applications. Recently, the use of biochar as filler in the preparation of polymer based composites received a great attention due to its ability to improve polymers mechanical, electrical and thermal properties. This work aims to expand knowledge on the effect of the heating rate and feedstock chemical composition on the on the biochar structural and chemical characteristics affecting electrical properties of the biochar at different pyrolysis temperatures. Biochars were produced from three feedstocks, namely walnut shells (WS), the lignin rich residue from bio-ethanol production (LRR) and sewage sludge (SS), under slow and fast heating rate at 500, 600 and 700°C. The three feedstock differ for both the organic components (i.e. high lignin content in WS and LRR and presence of proteins in SS) and ash content which is highest in SS. The produced biochars were characterized and the observed differences in their chemical and structural properties were discussed in relation to their effect on the measured electrical conductivity. The severity of the pyrolysis treatment improved biochars electrical conductivity. Heating rate and feedstock type affected the electrical conductivity only marginally at 500 and 600°C, whereas at 700°C any relevant effect was observed. WS biochars produced at 500 and 600°C exhibited the lowest electrical conductivity regardless of the heating rate of the production process. The biochars produced at 700°C were used to prepare epoxy resins composites. Despite their comparable conductive performance, the biochars lent different electrical conductivity to the composites depending on the biomass type and the heating rate experienced by the biomass samples during the pyrolytic treatment. The composite prepared with WS biochar produced under fast heating rate exhibited the highest electrical conductivity.

The structural and functional properties of polymer composite materials strictly depend on the spatial distribution of fillers, such as multiwalled carbon nanotubes (MWCNTs), inside the matrix. Herein, novel composites have been obtained by embedding MWCNTs into a modified polyvinyl alcohol (HAVOH) matrix, using the ionic liquid (IL) 1-Benzyl-3-methylimidazolium chloride (BenzImCl) as compatibilizer. The composites were prepared by solvent-wrapping carbon nanotubes onto HAVOH powders, followed by the melt-compounding approach to produce pellets for Fused Deposition Modelling technology (FDM). The efficacy of both the process and the IL on tailoring the spatial distribution of the MWCNTs into the HAVOH matrix is thoroughly studied and correlated with the electrical conductivity of the resulting composites. The sample printed by FDM, containing 6 wt % of MWCNTs and 0.6 wt% of IL exhibited a percolating morphology and led to an electrical conductivity (?) value of 1.2*10 S/m. Moreover, after annealing at 220 °C for 2 h the ? value increased up to 7.9*10 S/m. The thermal treatment in presence of the MWCNTs also induces the formation of crosslinked HAVOH molecules changing the composites from easily soluble to completely water insoluble materials. This revealed the potential of HAVOH-based composites as raw material for FDM technology to realize post-printing cross-linkable materials.

Currently, the increasing interest in polymer nanocomposites has been motivated by their potential to significantly improve the properties of obtainable products, thus accomplishing high design flexibility. In this work, experiments have been performed to analyze the filling ability of nanocomposite materials, in particular: Polyamide 6 (PA6) polymer matrix filled with Multi-wall carbon nanotubes (MWCNT) and Montmorillonite (MMT) as nanofillers. After compounding the pristine polymer, the resulting composite materials have been processed via micro injection molding. Different process conditions have been adopted to evaluate their filling ability in two mold designs, plates and ribs. The experimental results show that the compounded materials exhibit the same moldability characterizing the pristine polymer. This characteristic has been observed for all compounds regarding plate samples and only for MMT compounds regarding ribs. Moreover, a preliminary calorimetric characterization of PA6 plates and ribs has been also performed.

A simple and inexpensive method for the production of graphene-based masterbatch via polymer-assisted shear exfoliation of graphite in water was comprehensively investigated. In detail, a modified polyvinyl alcohol (mPVOH) characterized by surface energy comparable with that of graphene was used as surfactant for the production of graphene-like particles. The proposed approach allowed a yield in graphene-like particles higher than that obtained by using common surfactants, along with a narrower size distribution. A mPVOH-masterbatch containing 4.38 wt% of graphene-like particles was produced by removing the aqueous solvent from a dispersion and directly used for production of polymer nanocomposites by melt processing. Films prepared by blending the masterbatch with polyvinyl alcohol in order to have a graphene-like particles content equal to 0.3 wt% showed a 78% reduction in water permeability and a 48% increase in storage modulus as compared with pristine polymers. Improved barrier properties were also observed for polylactic acid (PLA) and low-density polyethylene (LDPE)-based composite films, whereas an increment of about 520% in the storage modulus was observed for the composite obtained with PLA. The obtained results are very relevant and the proposed process will open up a new pathway for using graphene-based masterbatch in the packaging industry.