High Char Yield Research Articles

Valorization of waste waxed corrugated cardboard via pyrolysis for recovering wax

AbstractCorrugated cardboard (CCB) comprises a substantial portion of municipal solid waste, of which ~5% is wax coated CCB (WCCB) to enhance its performance. WCCB cannot be recycled, making it a suitable resource to recover wax and produce char. The WCCB was characterized for its extractable wax, lignin, and carbohydrate contents and by thermogravimetric analysis to study its thermal degradation behavior. WCCB was preliminarily examined by pyrolysis‐gas chromatography–mass spectrometry to determine product composition. WCCB samples were then pyrolyzed in auger and tube reactors at 450, 500, and 550°C, and their pyrolysis wax‐oil and char products characterized. WCCB and char were subjected to proximate, ultimate, surface area, analyses. The highest char yield was 36% at 450°C, and the highest wax‐oil yield was 53% at 550°C in the tube reactor. The wax‐oil fraction contained mainly alkanes, alkenes, and dienes (C9–C36), and chain length decreased with pyrolysis temperature. This wax fraction could be recovered and used as bunker fuel (C12–C40) or further converted to diesel (C10–C20).

Aromatic dialdehyde-based bisbenzoxazines: The influence of relative position of oxazine rings

Polybenzoxazines are known to have superior thermal stability. Especially, the use of aromatic aldehydes instead of formaldehyde for the synthesis of benzoxazines monomers could improve this stability. However, the increase in aromatic content of the monomer can prevent the processability. The objective of this article is to understand the relationships between the conformation of an aromatic dialdehyde and its thermal properties. Two benzoxazine monomers were synthesized, based on salicylaldehyde, furfurylamine and respectively terephthalaldehyde (TPA, para configuration) and isophthalaldehyde (IPA, meta). Structural characterizations showed differences in intramolecular interactions between the two isomers. The melting transition of “meta” isomer was 50 °C lower than for “para” monomer, whereas polymerization temperatures and enthalpies were nearly the same. Volatile compounds released during the polymerization were the same in both cases, as investigated by mass spectrometry (Py-GC/MS). Curing kinetics using model-free kinetic methods revealed that the E-dependency follows the same trend for both monomers. Finally, thermal degradation monitored by thermogravimetric analysis under inert atmosphere was similar, with high degradation temperatures and high char yields (64%).

Structure-property relationships of cis-resveratrol cyanate ester blends

cis-ResCy is a relatively low melting cyanate ester monomer (<80 °C) derived from the renewable phenol, resveratrol. Thermal cross-linking of this material generates a high Tg polycyanurate network with a char yield >73% in air (600 °C). However, the monomer still presents processing challenges because it is a solid at room temperature and readily recrystallizes upon cooling below the melting point. In this study, cis-ResCy was blended with commercial cyanate ester resins (Primaset LeCy, PT15, and PT30) at loadings between 0 and 80% (by mass) to improve the processability of cis-ResCy and evaluate the structure-property relationships of the blends and corresponding networks. Blends with LeCy were low melting solids, while the PT15 and PT30 blends remained liquid after mixing. The cure chemistry of the blends was evaluated and the thermomechanical properties, thermal stability, moisture uptake, and hot/wet properties of the corresponding networks were studied. In general, the char yields of the blended networks increased with higher cis-ResCy loading. This result was most pronounced for the LeCy networks, which yielded much higher char yields (>70% in air) at ≥ 40% cis-ResCy loading compared to pure LeCy (<40% in air). The Tgs of the networks increased with increasing cis-ResCy content and reached temperatures as high as 391 °C after in-situ cure. Overall, the combination of cis-ResCy with various commercial cyanate esters allowed for the development of processable resins with higher Tgs, improved thermal stability, and lower moisture uptake than the monomer components.

Effect of different pre-treatments and addition of plastic on the properties of bio-oil obtained by pyrolysis of greenhouse crop residue

The bio-oil properties and yields during pyrolysis at 400, 500 and 600 °C of the residues from the cultivation of the pepper in greenhouse (Capsicum annuum L.) were studied. Different solid samples were investigated: the biomass fraction of the residue, the water-washed biomass sample, the cobalt-loaded biomass sample and three mixtures made with the biomass and plastic fractions of the residue. Results showed that temperature of pyrolysis has a moderate impact on the products’ yields and bio-oil properties for all solid samples. In general, the highest bio-oil yield was achieved operating at 600 °C while the higher char yield was reached at 400 °C. The pH of all the bio-oil samples was low, specially bio-oil from the cobalt-loaded biomass sample. Density, viscosity, cetane number, average boiling temperature, flashpoint, elemental analysis and ash content of the samples were analyzed and compared.The highest higher heating value was achieved for bio-oil (4218.6 kcal/kg) obtained from pyrolysis of the cobalt-loaded biomass sample. Infrared spectra and chromatography analysis revealed the presence of numerous compounds. Acetic acid is the main acid component of the bio-oil samples obtained from the biomass, the water-washed biomass and the cobalt-loaded biomass, although there are some differences in relative area. Other compounds such as ketones, phenolic or furans were also found. In bio-oils obtained from biomass and plastic mixtures, in general there was a decrease in the content of oxygenated compounds and acidic compounds, favoring the presence of non-oxygenated compounds. This work shows the feasibility of the obtaining of bio-oil from the greenhouse crop residue at the temperature range between 400 and 600 °C.

Effect of oxidative torrefaction on high temperature combustion process of wood sphere

The present work studies the effects of oxidative torrefaction (OT) (200–290 °C, 0–8 vol% O2) on the combustion process of wood sphere in a single particle combustor (SPC, 1226 °C, 3.0 vol% O2, wet basis), together with such effects on the yield, reactivity and morphology of the high temperature produced char. Increased torrefaction O2 concentration and temperature both result in higher char yield and prolonged combustion time, and the SPC char yield can be described by a linear regression equation (R2 = 0.85) as a function of the decreased mass yield caused by the OT process. The correlation (R2 = 0.83) between the low heating rate char yield (i.e., fixed carbon content) and the torrefaction mass yield is also validated against literature data, indicating that mass yield is a good indicator for both the OT and traditional inert torrefaction. The TGA analysis suggests that the char reactivity is significantly reduced by raised OT temperature up to 290 °C, while is only limited influenced by the increase in O2 concentration (up to 8 vol% at OT temperature of 260 °C). The NMR analysis of the OT wood and the SEM observation of the OT char produce from SPC show some evidences that OT result in a more cross-linked aromatic structure, which may hinder the volatile release in the subsequent pyrolysis and thereby lead to less porous char surface and a denser and heavier char particle.

Novel Polysilicone Flame-Retardant Functionalized Carbon Nanotubes: Synthesis, Characterization and Flame Retardancy as Used in Epoxy-Based Composites

Carbon nanotubes (CNTs) were covalently functionalized by a four components polysilicone (PMDA) to obtain novel, flame-retardant, polysilicone-functionalized carbon nanotubes (CNTs-PMDA). The chemical structure and thermal stability of the CNTs-PMDA were characterized and measured. Then, epoxy resin (EP)/CNTs-PMDA and EP/CNTs nanocomposites were prepared by a solution method, and thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and cone calorimetry were used to evaluate the thermal stability, dispersion state, and flame retardancy of the nanocomposites, respectively. The results showed that the thermal stability of the EP/CNTs-PMDA was better than that of the EP/CNTs, with a higher char yield, and the CNTs-PMDA were dispersed well in the EP matrix. Furthermore, the CNTs-PMDA could improve the flame retardancy of the EP nanocomposites with 2 wt% loading due to the synergistic flame-retardant effect between the PMDA and CNTs, having better flame retardancy than either one alone.

High temperature stable conjugated polyazomethines containing naphthalene moiety: Synthesis, characterization, optical, electrical and thermal properties.

A series of azomethine diol monomers containing naphthalene moiety were synthesized and oxidatively polymerized in aqueous alkaline medium using NaOCl as oxidant. The structure of the monomers and polymers was characterized by using various spectroscopic techniques. PL spectra of polymers are exhibiting good emission with high Stokes shift values than the monomers due to their polyconjugated structure. The electrical conductivity of polymers was measured by a two-point probe technique, and it increases with an increase in iodine vapour contact time up to 144h. The electrical conductivity values were correlated with the charge density on azomethine nitrogen obtained from the Hückel calculation method. The dielectric properties of polymers were studied at different temperatures in the frequency range from 50Hz to 5MHz. The synthesized polyazomethines have recorded high thermal stability and are shown by carbon residue of around 50% at 800°C in the thermogravimetric analysis.

Suppression of tar and char formation in supercritical water gasification of sewage sludge by additive addition

This study explored the feasibility of char and tar formation inhibition during supercritical water gasification of sewage sludge (SS) by additive addition. Experiments were conducted in autoclave with 5 wt% additives at 400 °C for 30 min. The non-additive gasification of SS resulted in a higher char yield (12.6%) and tar yield (16.4%). In contrast, the five additives reduced the char yield (3.4–11.2%), the inhibition of char yield by additives was in the order of NaOH > K2CO3 > H2O2 > acetic acid > NiCl2. The inhibition of tar formation was limited, tar yield were 13.3–18.8% with additives. Fourier-transform infrared spectroscopy was used to determine the functional groups of char/tar, and it was observed that the spectra of char were more similar to those of hydrochar obtained in a low-temperature experiment. Model compounds of potential precursors was also tested to study the mechanism of action of additives, the results reveal that additives have different effects on char/tar formation from various components, the inhibitory effects of additives on the yield of char from humus and tar from lignin were limited. Finally, the effects of additives on gasification were also studied. The addition of additives will have an impact on the hydrogen yield and gasification efficiency, which also needs to be considered when use additive to reduce the by-products yield.

Effect of regeneration solvent on the characteristics of regenerated cellulose from lithium bromide trihydrate molten salt

Dissolution and regeneration of cellulose is of vital importance for its end use. In the present work, the effect of different regeneration solvents (i.e. water, ethanol, and N, N-dimethylacetamide (DMAc)) on the characteristics of the regenerated cellulose from lithium bromide trihydrate (LBTH) molten salt was comprehensively investigated. It was found that the regenerated celluloses displayed obvious changes in macro- and micro-morphologies compared with the original microcrystalline cellulose (MCC). Furthermore, after the dissolution and regeneration process, the crystalline structure of cellulose was changed from cellulose I to cellulose II or amorphous structure, and the crystallinity of cellulose clearly decreased due to the deconstruction and rearrangement of cellulose chains. Moreover, the regenerated cellulose with ethanol had a relatively higher degree of crystallinity (70.2%) than that with water (42.3%) and DMAc (33.2%). Both X-ray Diffraction (XRD) and Attenuated Total Reflection Flourier transformed Infrared Spectroscopy (ATR-FTIR) analysis results indicated that ethanol as a regeneration solvent could be more beneficial to rearrange cellulose molecular chains and rebuild a more ordered structure compared to water and DMAc. In addition, thermogravimetric analysis showed that regenerated cellulose from LBTH exhibited a lower decomposition onset temperature and a higher char yield (over 17.8%) compared with the raw MCC (2.8%). The obtained results verified that regeneration solvents could substantially affect the reconstitution of cellulose molecule chains during regeneration as well as the multiscale structures and properties of the regenerated cellulose.

Semi‐fluorinated polyarylenes: Microwave‐assisted synthesis and structure–property relationships

AbstractA series of three fluorine containing and three non‐fluorinated Diels–Alder step‐growth polyarylene polymers and copolymers was synthesized via conventional oil bath heating (days/weeks). A drastic time reduction was realized with a microwave‐assisted polymerization (hours). The polymers were characterized by multinuclear (1H, 13C, and 19F) NMR and attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, thermal analysis (thermogravimetric analysis [TGA], differential scanning calorimetry [DSC], and dynamic mechanical analysis [DMA]), gel permeation chromatography, X‐ray diffraction (XRD), water contact analysis, and refractive index (RI) measurements. The NMR spectra indicated a mixture of para and meta conformations through the polymer backbone increasing to more para with greater fluorine content. TGA revealed the fluorine‐containing polyarylenes possessed the highest char yields at almost 80% at 1000°C under nitrogen, and all the polyarylenes possessed onset of degradation temperatures above 550°C under nitrogen and air atmospheres. XRD analysis indicated more ordering for the fluorine‐containing polyarylenes which afforded the high char yields. DMA gave storage moduli values in the range of 1–10 GPa for the polyarylenes. Molecular weights for all samples were above 100 kg/mol. Water contact angles did not change with fluorine content due to the shielding effect of the pendant phenyl groups. However, the RI decreased to 1.6497 at 632.8 nm for the polyarylene with the highest fluorine content.

Synthesis ofortho-methyltetrahydrophthalimide functional benzoxazine containing phthalonitrile group: Thermally activated polymerization behaviors and properties of its polymer

Two novel benzoxazine monomers, oHMTI-a and oHMTI-pn, have been obtained via the modified Mannich condensation from ortho-4-methyltetrahydrophalimide functional phenol, paraformaldehyde, and aniline/4-aminophthalonitrile, respectively. The chemical structures of both benzoxazine monomers have been studied by Fourier transform infrared (FT-IR) and1H and13C nuclear magnetic resonance (NMR) spectra. Their polymerization processes are investigated using in-situ FT-IR and different scanning calorimetry (DSC). Specifically, the phthalonitrile group in oHMTI-pn can react at a relatively lower temperature without adding any catalysts, which suggests the presence of the thermal synergistic polymerization effect in this benzoxazine monomer. In addition, the thermal and fire related properties of the resulting polybenzoxazines are evaluated by thermogravimetric analysis (TGA) and micro-scale combustion calorimetry (MCC). The polybenzoxazine derived from oHMTI-pn shows both high thermal stability and outstanding flame retardancy, with a Tgof 350°C, a Td10value of 417°C, a high char yield value of 65%, and a very low heat release capacity value of 35.2 J/(g·K).

Enhancement of Thermal and Mechanical Properties of Bismaleimide Using a Graphene Oxide Modified by Epoxy Silane.

A thermosetting resin system, based on bismaleimide (BMI), has been developed via copolymerization of 4,4′-diaminodiphenylsulfone with a newly synthesized graphene oxide modified using epoxy silane (ES-GO). The effect of ES-GO on the thermomechanical and mechanical properties of cured modified resin was studied. To evaluate the efficiency of the modified BMI systems, the composite samples using glass fiber cloth were molded and tested. Thermogravimetric analysis indicates that the cured sample systems displays a high char yield at lower concentrations of ES-GO (≤0.5 wt.%), suggesting an improved thermal stability. Using dynamic mechanical analysis, a marked increase in glass transition temperature (Tg) with increasing ES-GO content was observed. Analysis of mechanical properties reveals a possible effect of ES-GO as a toughener. The results also showed that the addition of 0.3 wt.% ES-GO maximizes the toughness of the modified resin systems, which was further confirmed by the result of analysis of fracture surfaces. At the same time, a molded composite with ES-GO showed improved mechanical properties and retention rate at 150 °C as compared to that made with neat resin.

An investigation on the pyrolysis of the main residue of the brewing industry

Brewer's spent grain (BSG) is the main by-product of the brewing industry. In this work, the pyrolysis of BSG using a fixed bed reactor was studied with respect to the valorization of this residue. The effects of the heating rate (10-50 °C/min) and temperature (450-650 °C) on the yields of pyrolysis products and on the physicochemical properties of the main products were quantified. The highest liquid yield (60.7%) was obtained at the pyrolysis temperature of 650 °C with a heating rate of 30 °C/min. The highest char yield (29.3%) was obtained at 550 °C and at heating rate of 10 °C/min. The results showed that high heating rates suppress dehydration reactions and favor bio-oil production. The produced biochar showed good potential for fuel application due to its high heating value (HHV) (27.1–28.3 kJ/g), moderate ash content (11.5%) and low sulfur content (<0.6%). The produced bio-oil contained phenols and ketones, which are precursors of several compounds used in the chemical industry, as well as pyrazines that are used in the pharmaceutical industry.

Advanced development of dairy farm waste-based biocarbon-reinforced unsymmetrical structured bio-phenolic polybenzoxazine composites

In the present work, an attempt has been made to develop cow manure carbon-reinforced hybrid biophenol-based benzoxazine composites for antifouling coating applications. Bio-based benzoxazine with unsymmetrical molecular structure was synthesized using the mixture of a combination of cardanol and eugenol with diaminodiphenyl methane and paraformaldehyde, and the hybrid-benzoxazine obtained was characterized using different analytical techniques, viz., Fourier transform infrared, nuclear magnetic resonance and MALDI mass. Bio-based benzoxazine was further reinforced with varying weight percentages (1, 3 and 5 wt%) of biocarbon derived from cow manure to obtain hybrid composite coatings. The hybrid benzoxazine matrix and composites were studied for their thermal behaviour, contact angle (CA), morphology, corrosion-resistant behaviour and antifouling character to utilize them as coatings materials for different industrial applications. Results obtained from different studies inferred that the biocarbon-reinforced composites possess an enhanced value of glass transition temperature (249°C), high char yield (38.4%), improved CA (105.6°), higher efficiency of corrosion protection against mild steel surface (98%) and improved antimicrobial activity.

Synthesis and properties of wholly aromatic phosphorus-containing thermotropic liquid crystal copolyesters with excellent fibre formation ability

ABSTRACT In this study, wholly aromatic phosphorus-containing thermotropic liquid crystal polymers (TLCP) derived from 6-hydroxy-2-naphthenic acid (HNA), terephthalic acid (TA) and 10-(2,5-Dihydroxypheny)-10 h-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO-HQ) are successfully synthesised via one pot melt polymerisation method. Although, the resulted copolyesters are amorphous, high glass transition temperature (182–196 °C) is observed due to the existence of kinked DOPO-HQ unit and crankshaft HNA monomer. The nematic liquid crystal behaviour is found for all of the copolyesters under POM at relatively low temperature (190–207 °C). The copolyesters show good thermal stability and high char yield under both nitrogen and air atmosphere, which of the initial degradation temperature (T5%) and char yield are above 450 °C and 50%, 439 °C and 29%, respectively. Dynamic rheology results show that viscous modulus of the obtained copolyesters are much more prominent under both frequency and temperature sweeping mode, indicating have excellent processing ability. The fibres can be easily drawn from the melt, and exhibit well oriented fibrillated structure. The convenient polymerisation method, excellent thermal stability and fibre formation ability of the phosphorus-containing TLCP endow them much potential use in the safety protection field.

Sulfonic-functionalized graphene oxide reinforced polyethersulfone nanocomposites with enhanced dielectric permittivity and EMI shielding effectiveness

We have explored the sulfonic-functionalized graphene oxides (S-GOs) as an efficient conductive reinforcement to enhance the dielectric permittivity and electromagnetic interference (EMI) shielding effectiveness of the polyethersulfone (PES). The S-GOs having numerous terminal -SO3− groups not only promote the homogeneous dispersion for achieving the low percolation threshold, but also induce strong H-bonding and dipole–dipole interactions at the interfaces. As-prepared S-GO nanosheets showed uniform dispersion in PES matrix with strong adhesion with the polymer matrix via non-bonding interactions. The remarkable enhancement of dielectric permittivity of PES upon inclusion of S-GOs could be attributed to the interfacial polarization effect and microcapacitor model. As-prepared nanocomposites exhibited low conductive percolation threshold. The well-wrapped graphene nanosheets by thin PES layer prevented direct contact of graphene nanosheets and consequently decreased the dielectric loss by suppressing the current leakage. The PES/S-GO nanocomposites exhibited significant improvement in thermal stability with high char yield in N2 atmosphere compared to pure PES. A high EMI shielding effectiveness of 23.5 dB was achieved for the nanocomposite film with 5 wt% graphene loading, which might be originated from the development of conductive network at higher graphene loading. Overall, the as-prepared PES/S-GO hybrid nanocomposite could be used in DC and radiofrequency electronics.

Tuning the architecture and performance of multifarious benzoxazine resin based on guaiacol and polyethylenimine

Molecular designing flexibility offered by benzoxazine chemistry, has been utilized to synthesize side-chain benzoxazine functionalized resins, in one-step approach via reaction of polyethylenimine (PEI) and guaiacol. The functionalization of polyethylenimine bearing amine functionalities, with benzoxazine groups as side-chains, is expected to confer a densely cross-linked network in the resulting thermoset. In the present work, guaiacol has been chosen as bio-based phenol, and polyethylenimine enriched with primary, secondary, tertiary amine groups, has been employed as an amine co-reactant. The reactants stoichiometry (phenol: amine: paraformaldehyde) has been varied from 2:1:4 to 20:1:40 molar ratio, resulting in a series of side-chain type guaiacol based benzoxazine-functionalized polyethylenimine resins (G-pei), which differ in percentage of oxazine functionalization. All the resins prepared have been characterized using FTIR, 1H, 13C NMR spectroscopies, and the evolution of oxazine functionalization in the resins has been monitored via 1H NMR spectroscopy. The polymerization behaviour in resins has been evidenced using non-isothermal DSC studies, which reveals that G-pei resins exhibit peak polymerization temperature (Tpeak) below 200 °C. Temperature sweep rheological experiments have been performed to obtain flow behaviour and processing window of the developed resins, where an evident reduction in the viscosity of resins has been observed around 100 °C, thereby making it an appropriate temperature for processing. The influence of polar groups on the surface property of thermosets has been investigated by performing contact angle measurements, which reveals the hydrophilic nature of prepared thermosets. Thermal degradation behaviour of the multifarious bio-based thermosets, has been studied using thermogravimetric analysis, where maximum degradation temperature (Tmax) for the cured specimens has been found to be above 300 °C, with a high char yield (30–50%). The influence of dense network on the glass transition temperature of thermosets, has been additionally studied by DSC experiments. The adhesive performance of side-chain type benzoxazine-functionalized polyethylenimine resins, enriched with oxazine functionalities as well as polar groups, has been evaluated by lap shear strength values, which have been observed in the range of 22 to 49 Kg/cm2.

Improved interfacial adhesion with the help of functional polyhedral oligomeric silsesquioxanes in silicone rubber/rayon fiber composites: Physical, mechanical, thermal, and morphological properties

AbstractThe aim of this article is to improve the interfacial adhesion between silicone rubber (SR) and Rayon fiber by the help of functional hybrid POSS nanoparticles. Two POSS types were compared, octavinyl‐POSS (O‐POSS) and methacryl‐POSS (M‐POSS), having reactive CC double bonds that can impart in peroxide crosslinking. O‐POSS is nonpolar, whereas M‐POSS is polar and is able to make H‐bond with Rayon fibers. POSS type and their concentrations were examined as the experimental parameters. H‐adhesion tests indicated that both POSS types enhanced the adhesion of SR composites to Rayon fibers compared with control recipe. Specifically, slightly higher values were obtained with the use of M‐POSS. It was observed that both O‐POSS and M‐POSS slowed down the curing rate but increased the degree of crosslinking. The cure extent of O‐POSS containing composites was found to be higher than that of M‐POSS containing ones. Thermal gravimetric analyses revealed that thermal stability of SR composites was significantly improved by the addition of POSS particles. Higher char yield and degradation temperatures were obtained with O‐POSS at higher loadings with respect to M‐POSS. The POSS distribution at lower loading levels was found to be homogenous for both POSS types as observed from scanning electron microscope and transmission electron microscope.

Study of Electron Beam Pre-Irradiation on Char Yields of Polyacrylonitrile

Thermal treatment of polyacrylonitrile (PAN) with different molecular weights pre-irradiated by electron beam was prepared to study the radiation effects on thermal behaviors. Thermal properties were characterized by thermogravimetric analyses. Char yields (800 oC) of PAN samples are increased remarkably with the increase of irradiation dose, and all samples can obtain the similar high char yields (~57 %) at the dose of 300 kGy. FTIR and UV-visible absorption spectra of pre-irradiation PAN illustrate the formation of –HC=N-N=CH-crosslinking conjugation across the polymeric chains, which can improve PAN’s thermal behaviors. Char yields of pre-irradiated PAN samples are mainly dominated by their gel contents, and they are almost independent of the molecular weights of PAN samples.

Torrefaction of biomass and plastic from municipal solid waste streams and their blends: Evaluation of interactive effects

This paper investigated the interactive effects between biomass and plastic, derived from municipal solid wastes, during co-torrefaction of their mixtures. Mango branches (MBr), waste newspaper (Np), low-density polyethylene (LDPE) and their blends were torrefied at 300 °C at a constant heating rate of 10 °C/min for 30 min using a bench-scale reactor. Statistically significant interactions were found between MBr and Np during torrefaction of MBr-Np and MBr-Np-LDPE blends. The synergistic behaviour in torrefied MBr-Np accounted for its improved energy density, reduced volatile matter content, increased carbon content and higher fuel ratio than expected. During co-torrefaction with plastic, melted LDPE limited mass transfer, which resulted in higher char yield and energy content. Analysis of combustion indices revealed that waste blending ratio of torrefied biomass-LDPE blends should be limited to 5 wt%, due to the high volatile matter content of LDPE. This study elucidates that among the different torrefied blends, synergistic interactions during co-torrefaction of waste biomass (MBr-Np) generated a char with improved fuel characteristics that allowed co-firing of biomass at higher blending ratios (20 wt%).