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Kenaf polypropylene composites with high fiber load of 85 wt% were produced using glycerine as a processing aid and maleic anhydride-grafted polypropylene (MAPP) as a compatibilizer/coupling agent. Commercially available MAPPs with different molecular weights and anhydride contents were used to determine what properties of the MAPPs were important to achieve high mechanical properties of these highly filled composites. A homo-polymer and a random-polymer, were compared as matrix polymers. Composites were produced using a high-shear kinetic mixer followed by compression molding at pressures ranging between 345 and 5520 kPa. The data suggests that adding MAPPs with a low molecular weight and high anhydride content at concentrations of 5 wt% resulted in composites with the highest mechanical properties. The authors suggest that a combination of a high surface area, low viscosity and high anhydride content of the MAPP are resulting in a good stress transfer between fibers and matrix polymer.

The global production of coconut, mainly for food and oil production, exceeds 62 million tonnes per annum. Large quantities of coconut husk remain unutilized after industrial processing, giving rise to environmental problems. This fails to exploit the potential presented by the extraction of coir, which could have numerous applications. Traditional products such as textiles, mats, and brushes made from coir are increasingly being joined by new, high-value, non-traditional uses. This review article summarizes new fields of application for coir as reinforcing fibers in binderless fiberboards, natural fiber composites, construction materials, solid biofuels, and an absorbent for heavy metals and toxic materials. The use of coir in these new fields will reduce waste and increase sustainability.

Interior wood panel products (plywood, particle board, etc.), typically use urea-formaldehyde (UF) to bind wood pieces together. Conventionally, UF is used due to their fast-curing characteristics, easy workability, and low cost. However, these glues release carcinogenic formaldehyde and legislations are therefore aimed at decreasing the emitted amount. Proteins can be a biologically based and formaldehyde-free alternative. This work presents the first results of using Danish grass proteins as wood adhesives.

In this work, we aimed to analyze suspensions of cationic starch by adding 5 wt%, 7 wt%, and 10 wt% of bentonite as a bilayer coating on kraftliner paper (85 g/m2). The controls were doubly-wet-and-dry and uncoated kraftliner paper. In a coating machine, the formulations were applied until reaching a grammage of 15 g/m2 and then dried at 103 ± 2 °C. The test was carried out about pH, solids content, and viscosity of the suspensions. The physical characteristics of the coated papers were evaluated, as well as their ability to block water, water vapor, and oil/grease. We also analyzed with scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy. The packaging, having a water contact angle of up to 78° and 189 g/m² for Cobb, showed a low resistance to water, which is further responsible for decreased mechanical resistance. Nevertheless, the coating did not change the permeability to water vapor, however, bentonite promoted a decrease in wettability and Cobb value of the paper. The addition of 7 wt% bentonite to the cationic starch matrix promoted high oil resistance with 12 for kit-oil, while 10 wt% bentonite promoted greater pencil hardness, with a value of 8H. Bentonite strength and cationic starch showed good interaction, increasing oil resistance.

Sugars are a sustainable platform for producing chemicals and polymers, while cellulose nanofibers (CNF) are sustainable materials with high specific mechanical properties that have an important role to play in many applications. This study highlights the feasibility of producing sugars and CNF using high dry matter (DM) content of 20 %. A commercial enzyme cocktail at low dosage, 5 mg EP/g DM, and a high 15 mg EP/g DM, were used to hydrolyze the pulp cellulose to produce sugars and CNF. HPLC was used to evaluate the cellulose conversion rate and amount of sugar realized. The CNF were studied using TEM, the diameter of the CNF were measured and estimate the crystallinity. The cellulose conversion plateaued at about 48 h for both the low and high dosage, indicating inhibition due to higher sugar concentration and/or increased recalcitrance of the remaining CNF. The CNF obtained at low enzyme indicated the fibrils were insufficiently separated. At the high dosage, less clumps were observed and with smaller diameter than with the low enzyme dosage. The high dosage also produced CNF with significantly higher crystallinity index, confirming that amorphous cellulose portions readily underwent enzymatic hydrolysis and left more recalcitrant CNF.

The aim of this research was to investigate sugarcane bagasse (SCB) particleboards, using two kinds of particles, from pith and fibers, reinforced with cellulose nanocrystals (NCC). The NCCs were dispersed in the adhesive urea formaldehyde (UF) using a sonificator in two proportions (0 and 1%). The NCCs and UF were applied in the SCB particles using a rotary blender. The particleboards were produced in three layers using two kinds of particles: pith and fibers. After dispersion of the adhesive, the mixture was compressed to produce the particleboards, which were characterized by physical, mechanical and thermal properties. The anatomical and chemical features relating to pith and fiber were very similar. The particleboards made with and without NCCs did not differ statistically for most properties: modulus of elasticity (MOE), modulus of rupture (MOR), water absorption (WA) thermal conductivity (TC), and the volume heat capacity (VHC). Particleboards made only with fibers and without NCCs showed higher internal bond (IB). In the other hand particleboards made only with fibers in the face and pith in the core (without NCCs) showed lower thickness swelling after 24 hours (TS24h). Probably, the NCCs did not improve the particleboards performance, because less links were available for SCB to interact with the adhesive. For the others properties the particleboards made with pith and fibers did not showed statistical difference (MOE, MOR, TC, WA, TC and VHC), demonstrating that separation of pith and fiber are not significant and does not affect the final properties of particleboards.

Nanoparticles are often added to coatings in order to improve their mechanical properties. However, nanoparticles can also influence the cross-linking reaction of polymers and overall curing kinetics, and from this follows that properties of interest are further impacted. In research studies on alkyd-based coatings, only the physical drying stage during the first 24 h has been studied in this respect until now. In this study, it was shown with the use of Raman spectroscopy that colloidal nano-silica can change the rate of alkyd autoxidation and how this effect is reflected on the tensile properties of the coating. One of the consequences of the influence of nano-silica on curing kinetics is that, contrary to implicit assumptions of common testing methods, the real effect of nanoparticles on mechanical properties can emerge much later in the coating lifetime.

Wood has been used for thousands of years and remains an important material in the construction industry, most often protected with coatings. Development of nanotechnology allows further improvements or new performance properties to be achieved in wood coatings. Increased UV protection with nanometal oxides that allow wood texture to remain seen and higher resilience to scratch and abrasion with use of different nanoparticle shapes are some of the applications that are reviewed here. A variety of possible applications together with a high level of improvements, alongside commercial factors like a low level of loading, have already established nanoparticles in some areas of wood coatings. This article is a comprehensive scientific review of the published work in the use of nanofillers in wood coatings.

Lignin is an abundant plant polymer usually regarded as waste material. In the present work, antioxidant properties of lignin preparations with differing lipid solubility were studied using biodiesel as a convenient lipid test substrate. In place of formerly used assays, we used attenuated total reflectance (ATR) FT-IR spectroscopy to follow in situ biodiesel autoxidation on a heated ATR crystal as a function of time. The study demonstrates that a complex balance between intrinsic (chemical) efficiency, solubility, and particle formation controls the antioxidant efficiency of differently prepared lignin fractions. It was found that solubility and particle formation of lignin preparations strongly modulate its antioxidant efficiency and that these properties might depend on the presence of lipid components within the original lignin source.

This paper is an initial study of the implementation of two new enzymes, an endoglucanase and a concoction of hemicellulases and pectinases to obtain cellulosic nanoparticles. In this study, curauá and sugarcane bagasse were dewaxed and bleached prior to enzymatic action for 72 h at 50 °C, and then followed by sonication. The concentration between these two enzymes was varied, and for the concentrations and time of enzymatic treatment used, subsequent sonication was necessary for cellulose nanoparticle release. It was easier to extract cellulose nanofibers from sugarcane bagasse which resulted in nanoparticles without damage of cellulose chains. On the other hand, curauá fibers needed a higher concentration of enzymes and the nanofibers obtained displayed a decrease of crystallinity suggesting that the cellulose structure was compromized. For both fibers, cellulose nanocrystals (single crystals) and larger diameter nanofibers were attained after the sonication. Look Inside Share

The purpose of the study was to investigate the influence of torrefaction on the grindability of wheat straw. Straw samples were torrefied at temperatures between 200 °C and 300 °C and with residence times between 0.5 and 3 h. Spectroscopic information obtained from ATR-FTIR indicated that below 200 °C there was no obvious structural change of the wheat straw. At 200–250 °C hemicelluloses started to decompose and were totally degraded when torrefied at 300 °C for 2 h, while cellulose and lignin began to decompose at about 270–300 °C. Tensile failure strength and strain energy of oven dried wheat straw and torrefied wheat straw showed a clear reduction with increasing torrefaction temperature. In addition, Hardgrove Grindability Index (HGI) of wheat straw torrefied at different conditions was determined on a standard Hardgrove grinder. Both results showed an improvement of grindability in the torrefaction temperature range 250–300 °C, which can be well explained by the findings from FTIR analysis. At a torrefaction temperature of 260 °C and with a residence time of 2 h, wheat straw samples produced similar HGI values as coal (RUKUZN) with 0% moisture content. Under this condition, the Anhydrous Weight Loss (AWL%) of the wheat straw sample was 30% on dry and ash free basis (daf), and the higher heating value of the torrefied wheat straw was 24.2 MJ kg−1 (daf). The energy loss compared to the original material was 15% (daf).

The utilization of wheat straw as a renewable energy resource is limited due to its low bulk density. Pelletizing wheat straw into fuel pellets of high density increases its handling properties but is more challenging compared to pelletizing woody biomass. Straw has a lower lignin content and a high concentration of hydrophobic waxes on its outer surface that may limit the pellet strength. The present work studies the impact of the lignin glass transition on the pelletizing properties of wheat straw. Furthermore, the effect of surface waxes on the pelletizing process and pellet strength are investigated by comparing wheat straw before and after organic solvent extraction. The lignin glass transition temperature for wheat straw and extracted wheat straw is determined by dynamic mechanical thermal analysis. At a moisture content of 8%, transitions are identified at 53°C and 63°C, respectively. Pellets are pressed from wheat straw and straw where the waxes have been extracted from. Two pelletizing temperatures were chosen—one below and one above the glass transition temperature of lignin. The pellets compression strength, density, and fracture surface were compared to each other. Pellets pressed at 30°C have a lower density and compression strength and a tendency to expand in length after the pelletizing process compared to pellets pressed at 100°C. At low temperatures, surface extractives have a lubricating effect and reduce the friction in the press channel of a pellet mill while no such effect is observed at elevated temperatures. Fuel pellets made from extracted wheat straw have a slightly higher compression strength which might be explained by a better interparticle adhesion in the absence of hydrophobic surface waxes.

Attenuated Total Reflectance (ATR) FT-IR spectroscopy gives in situ information on molecular concentration, organization and interactions in plant cell walls. We demonstrate its potential for further developments by a case study which combines ATR-FT-IR spectroscopy with a recently published DFT method for polysaccharide IR band assignments. Palm kernel cake is enzymatically hydrolyzed and fermented, which targets cellulose and mannan in particular. The DFT method helps to identify their spectral changes and gives new knowledge on their spectral signatures. This method thus provides a prerequisite for FT-IR analysis. The removal of mannan is identified and correlates with positional shifts of both the mannan glycosidic linkage vibration at 1180 cm-1 and the 896 cm-1 cellulose exocyclic C6H2 vibration. This indicates a cellulose environment change, and for mannan the theoretical results show a decreasing degree of polymerization to be a plausible cause, although others may interfere. Keywords: Cellulose; Mannan; FT-IR; DFT; Molecular modelling; Palm kernel