A Review of Bio-Oil Production through Microwave-Assisted Pyrolysis

The issue of sustainability is a growing concern and has led to many environmentally friendly chemical productions through a great intensification of the use of biomass conversion processes. Thermal conversion of biomass is one of the most attractive tools currently used, and pyrolytic treatments represent the most flexible approach to biomass conversion. In this scenario, microwave-assisted pyrolysis could be a solid choice for the production of multi-chemical mixtures known as bio-oils. Bio-oils could represent a promising new source of high-value species ranging from bioactive chemicals to green solvents. In this review, we have summarized the most recent developments regarding bio-oil production through microwave-induced pyrolytic degradation of biomasses

Novel bioplastic from single cell protein as a potential packaging material

Microbial treatment of biodegradable wastes not only ensures neutralization of harmful substances such as volatile organic compounds but also enables valorization and bio-circularity within the society. Single cell protein (SCP) is a value-added product that can be obtained from biodegradable waste materials such as food waste via microbial fermentation. In this article, SCP derived from potato starch waste was demonstrated as a viable alternative to existing plant/animal proteins used in the production of films, for example, packaging applications. Flexible glycerol-plasticized SCP films were prepared through compression molding, and tensile tests revealed strength and stiffness similar to other plasticized protein films. The oxygen barrier properties were significantly better compared to the common polyethylene packaging material, but as with other highly polar materials, the SCP material must be shielded from moisture if used in, for example, food packaging. The biodegradation test revealed a similar degradation pattern as observed for a household compostable bag. The results showed that SCP-based bioplastic films can be considered as potential alternative to the existing plant/animal protein films and certain synthetic polymers. An important advantage with these protein materials is that they do not cause problems similar to microplastics

Influence of large-scale asperities on the stability of concrete dams

For concrete dams founded on rock, there are only a few options in the common analysis methods to account for large‐scale asperities. However, previous research alludes that they have a significant impact on the behaviour of interfaces under shear. This study investigates the behaviour of concrete dam scale models with varying interface geometries, under a realistic set of eccentric loads. The outcome of the scale model tests shows that not only the capacity of the scale models was significantly impacted by the asperities, but also the type of failure in the scale models.Influence of large-scale asperities on the stability of concrete damspublishedVersio

The Effect of Carbon Black on the Properties of Plasticised Wheat Gluten Biopolymer

Wheat gluten biopolymers generally become excessively rigid when processed without plasticisers, while the use of plasticisers, on the other hand, can deteriorate their mechanical properties. As such, this study investigated the effect of carbon black (CB) as a filler into glycerol-plasticised gluten to prepare gluten/CB biocomposites in order to eliminate the aforementioned drawback. Thus, biocomposites were manufactured using compression moulding followed by the determination of their mechanical, morphological, and chemical properties. The filler content of 4 wt% was found to be optimal for achieving increased tensile strength by 24%, and tensile modulus by 268% along with the toughness retention based on energy at break when compared with those of glycerol-plasticised gluten. When reaching the filler content up to 6 wt%, the tensile properties were found to be worsened, which can be ascribed to excessive agglomeration of carbon black at the high content levels within gluten matrices. Based on infrared spectroscopy, the results demonstrate an increased amount of beta -sheets, suggesting the formation of more aggregated protein networks induced by increasing the filler contents. However, the addition of fillers did not improve fire and water resistance in such bionanocomposites owing to the high blend ratio of plasticiser to gluten

A Novel Way of Adhering PET onto Protein (Wheat Gluten) Plastics to Impart Water Resistance

This study presents an approach to protect wheat gluten (WG) plastic materials against water/moisture by adhering it with a polyethylene terephthalate (PET) film using a diamine (Jeffamine®) as a coupling agent and a compression molding operation. The laminations were applied using two different methods, one where the diamine was mixed with the WG powder and ground together before compression molding the mixture into plates with PET films on both sides. In the other method, the PET was pressed to an already compression molded WG, which had the diamine brushed on the surface of the material. Infrared spectroscopy and nanoindentation data indicated that the diamine did act as a coupling agent to create strong adhesion between the WG and the PET film. Both methods, as expected, yielded highly improved water vapor barrier properties compared to the neat WG. Additionally, these samples remained dimensionally intact. Some unintended side effects associated with the diamine can be alleviated through future optimization studies

Effects of pretreatments on the yield and composition of bio-oil from the auger pyrolysis of woody biomass

The effect of different pretreatments (hot water, thermal pretreatment and the use of additives: 0.3 mass % H2SO4 and 0.3 mass % NH4H2PO4) on the production of pyrolytic sugars (Levoglucosan and hydrolysable sugars) from Douglas fir and Hybrid Poplar were studied. Treated and untreated biomasses were characterized to understand the effect of pretreatment conditions on their overall chemical makeup. The thermal behavior and the pyrolysis activation energy for each of the untreated and pretreated samples were studied by Thermogravimetry. The use of NH4H2PO4 as additive significantly increases pyrolysis activation energy most likely due to the modification of lignin thermal degradation mechanism. Douglas fir samples (as received and after pretreatment) were pyrolysed in an Auger Pyrolysis Reactor and the yield of products was determined. The chemical composition of bio-oil produced was characterized by KF-titration, GC/MS, TG, Cold water precipitation and IEC. The use of H2SO4 as additive increased the bio-oil yield by 10 mass %. The other treatments do not have an important impact on oil yields. Although H2SO4 and NH4H2PO4 increases the content of levoglucosan in the oils by 6 and 4 mass % respectively, none of the pretreatments studied have any important effect on the content of total fermentable sugars. An important finding of this thesis is a reduction in the content of pyrolytic lignin in the oil by 6 and 12 mass % when using H2SO4 and NH4H2PO4 as additives. This finding suggests that these additives modify the thermal degradation of lignin and consequently its interactions with cellulose. The use of these additives may be recommended if the end use of the oil is to develop high value products from levoglucosan

Comparison of tension wood and normal wood for oxidative nanofibrillation and network characteristics

Cellulose nanofibrils (CNFs) are top-down nanomaterials obtainable from abundant lignocelluloses. Despite recent advances in processing technologies, the effects of variations in the lignocellulose structure and composition on CNF isolation and properties are poorly understood. In this study, we compared the isolation of CNFs from tension wood (TW) and normal wood (NW) from Populus tremula (aspen). The TW has a higher cellulose content, native cellulose fibrils with a larger crystalline diameter, and less lignin than the NW, making it an interesting material for CNF isolation. The wood powders were oxidized directly by 2,2,6,6-tetramethylpiperidin-1-oxyl, and the morphology and mechanical behaviors of the nanofibril suspensions and networks were characterized. The TW was more difficult to fibrillate by both chemical and mechanical means. Larger nanofibrils (5-10 nm) composed of 1.2 nm structures were present in the TW CNFs, whereas the NW samples contained more of thin (1.6 nm) structures, which also comprised 77% of the solid yield compared to the 33% for TW. This difference was reflected in the TW CNF networks as decreased transmittance (15% vs. 50%), higher degree of crystallinity (85.9% vs. 78.0%), doubled toughness (11 MJ/m(3)) and higher elongation at break (12%) compared to NW. The difference was ascribed to greater preservation of the hierarchical, more crystalline microfibril structure, combined with a more cellulose-rich network (84% vs. 70%). This knowledge of the processing, structure, and properties of CNFs can facilitate the breeding and design of wood feedstocks to meet the increasing demand for nanoscale renewable materials.[GRAPHICS]

Special issue “recent advances in flame-retardant polymers and composites”

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Thermal History Effects on Decomposition Behavior and Pyrolysis Mechanism of Cellulose Nitrate

Nitrocellulose is an important kind of energetic material produced by replacing hydroxyl of cellulose molecule to nitro, which has a wide application range in social life. During transportation and storage, inevitably the quality of the nitrocellulose will be affected due to external ambient heating. In this study, two kinds of NC samples, original and heated ones, were used as research objects and taken into DSC experiments under several constant heating rates to explore thermal history effects on its decomposition and combustion behavior. A series of calculation methods based on model fitting were main ways for research, so were model free methods. Numerical results by model fitting method showed that decomposition reaction of NC follows n-th reaction model. The comparison between experimental results of two kinds of samples claimed that thermal history had positive influence on heat flow, and increased the reaction order of decomposition process, and decreased the characteristic temperatures. So the thermal history made the decomposition reaction more difficult to take place and more stable. This study is obviously meaningful for the research of thermal pyrolysis process of NC after thermal history.Funder: National Natural Science Foundation of China (NSFC, Grant 51806208); Postgraduate Research &amp; Practice Innovation Program of Jiangsu Province (Grand KYCX19_0333)Licens fulltext: CC BY 3.0</p

Response to the comments made by Vytenis Babrauskas on “the curious case of the second/end peak in the heat release rate of wood: A cone calorimeter investigation”

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