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Increased knowledge on the correlation between pulp processing, fibre-properties and paper properties is required to improve fibre-based products. Part 1 of this investigation deals with the effects of HC and LC refining on fibre properties development. LC refining reduced curl and increased tensile index in a manner similar to hot disintegration whereas HC refining increased curl slightly. In this second part, the correlation between fibre curl and handsheet properties of thermomechanical pulp, subjected to low consistency (LC) refining and hot/cold disintegration is examined. Fibre curl decreased by laboratory disintegration and LC refining and showed a linear correlation with increased tensile index and tensile stiffness. Evaluation of fibre property distributions gave a more detailed description of the development of fibre properties. These revealed that disintegration and LC refining gave different fibre curl versus fibre length distributions, even when their average values were similar. These results confirm that analysing fibre property distributions contributes to a more detailed knowledge of the development of pulp quality. Hot disintegration before laboratory testing exaggerated pulp quality and increase internal fibrillation and can therefore be questioned. When hot disintegration is performed before pulp analyses, the impact of LC refining on paper properties may be misjudged. [ABSTRACT FROM AUTHOR]

Pressure to increase the renewable energy matrix motivates the search for new energy sources. Pulp and paper mills have been constantly expanding in Brazil, and to ensure their competitiveness, new processes should be established both in terms of reducing the waste discarded in landfills, as well as the substitution of fossil fuels used in the mills. The present work aims to evaluate the energy potential of primary sludge (PS), secondary sludge (SS), a mixture of primary and secondary sludge (MS) and tree bark (B) generated in a Brazilian TMP mill. Characterization of all biomasses was performed. Moisture content, higher, lower, and net heating value, elemental, structural, and immediate composition, thermogravimetric analysis and quantification of minerals and metals were determined The bark presented the highest higher heating value (HHV) (18.90 MJ kg−1), while the secondary sludge had the lowest HHV (12.45 MJ kg−1). The high concentration of ash in the sludges PS (26.58%), SS (40.46%) and MS (25.78%) negatively affected their heating value. The sludges also showed high moisture content, which made their burning without a previous drying stage unattractive. Nevertheless, the sludges and the bark are rich in carbon which makes them attractive for use as biomasses for energy generation. [ABSTRACT FROM AUTHOR]

Delignification and fractional pretreatments are essential for valorization of wood biomass in various bioproducts. Herein, lignocellulose wood fibers were exposed to a eutectic mixture (EM) of carvacrol and methanesulfonic acid for different times. The resulting structural and chemical alterations in biomass were explored in terms of the fiber morphology and fractional chemical composition through fiber image analysis, field-emission scanning electron microscopy, high-performance liquid chromatography, and a novel approach based on fluorescence-lifetime imaging microscopy (FLIM). The autofluorescence of the lignocellulose fibers, which was primarily due to lignin with contributions from cellulose and hemicellulose, enabled application of FLIM in lignocellulose compositional analysis in micro-scale. FLIM analysis revealed that EM treatment efficiently removed lignin from the outer fiber layers. Furthermore, the effective EM treatment time was 3 h (with a residual lignin content of ~ 7 wt%), after which defects were observed on the fibers and the cellulose chains started breaking. This degradation was also indicated by a shift of the lifetime spectra toward the fluorescence lifetime of cellulose with increasing treatment time. Overall, our findings provide valuable insights to the response of lignocellulose fibers to EM treatment, contributing to the important goal of wood biomass application in bioproducts. [ABSTRACT FROM AUTHOR]

Alkyl ketene dimers (AKDs) are known to efficiently react with cellulose with a dual polarity in their structure: a polar component and a nonpolar component. AKD of three different carbon chain lengths, 4, 10, and 16 carbons have been synthesized, and thermomechanical pulp (TMP) fibers were modified by them. The modification of TMP fibers with AKD resulted in an increased water contact angle, showing the presence of the AKDs on the TMP fibers and a new carbonyl peak in the IR spectra, suggesting modification of the TMP fibers with AKD groups. Calculating the Hansen solubility parameters of AKD and AKD conjugated to TMP in polypropylene (PP) indicates improved compatibility, especially of longer chain AKD and TMP AKD. The rheological studies of the composites showed that the AKD with the longest carbon chain decreases the melt viscosity of the PP‐TMP‐AKD composite, which combined with the shape and the color of the extruded composite filaments indicates improved flow properties and reduced stress build up during processing. The research findings demonstrate the ability of AKD to enhance the dispersibility and compatibility of natural fibers with PP. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) bleaching in ethanol-water media was used to improve the bleaching efficiency of the chemi-thermomechanical pulp (CTMP). The brightness of CTMP increased and the yellowness decreased when the ethanol ratio was increased to 50%. However, when more than 50% ethanol was added, the brightness decreased, and the yellowness increased. In general, H2O2 bleaching in ethanol-water media, except for 100% ethanol, improved the optical properties of CTMP compared to conventional H2O2 bleaching. Moreover, the chemical composition of CTMP did not alter significantly. The best bleaching condition for CTMP was observed in 50% ethanol at a bleaching temperature and time of 80 °C and 120 min, respectively. The brightness of CTMP under this condition increased by approximately 22% compared with conventional H2O2 bleached CTMP. Principal component analysis (PCA) revealed that the optical properties of bleached CTMP were affected by the structural changes of the aromatic ring and carbonyl group in lignin and carbonyl group in hemicellulose. Consequently, the specific optimal ratio of ethanol that could improve the optical properties of CTMP was determined. The results can serve as a reference for fabricating improved CTMP for its practical application in high-grade papermaking.

Previously it was shown that wood chip compression or enzyme impregnation prior to refining reduces energy consumption and improves pulp quality. This work characterizes the effect of different magnitudes and rates of compression on the extent of enzymatic hydrolysis. A laboratory compressor and a controlled uniaxial load set-up were used to apply different compression ratios and compression times to mixed-softwood wood chips. The chips were subsequently subjected to enzymatic hydrolysis with a high-yield exoglucanase preparation to demonstrate changes in cellulose hydrolysis. Enzymatic hydrolysis yield increased with compression ratio but was unaffected by compression time. Increasing compression ratio increased removal of soluble molecules such as sugars and acid-soluble lignin. Microscopy imaging showed increased cell wall buckling and fracturing with increased compression. The morphological changes led to improved enzyme diffusion and resulted in higher available surface area. The improved cellulose hydrolysis is due to changes in wood morphology as well as the removal of extractives. [ABSTRACT FROM AUTHOR]

Bio-based lightweight materials are promising replacements for petroleum-based foams in building and packaging applications. In this work, we developed a surfactant-assisted foam-forming method to manufacture lightweight materials based on lignocellulosic fibers (thermomechanical pulp (TMP), refined wood fibers (RWF) and pine flour (PF)) enabled by cellulose nanofibrils (CNFs). Sodium dodecyl sulfate (SDS) or cetyltrimethylammonium bromide (CTAB) at 1 g/L concentration was mixed with different concentrations of CNFs in a blender followed by the addition of a pre-determined amount of TMP, RWF or PF. The preparation of hybrid foams using TMP/PF, TMP/RWF, and TMP/PF/RWF at different weight fractions was also investigated. Results showed that among the three tested natural fibers, TMP was the best for the preparation of low-density foamed materials, with densities ranging from 11 to 45 kg/m3 in the case of foams made with SDS and 16–90 kg/km3 for those made with CTAB. Thermal conductivity of the prepared foams was between 0.031 W/m.K and 0.055 W/m.K depending on the density and the porosity of the foams. Foams made with high solids content (4–6 wt%) exhibited excellent sound absorption coefficients (0.96–1 at 3500 Hz). Water stability and mechanical properties of the resulting bio-foams were significantly improved when increasing CNF and solids contents. All foams exhibited antifungal properties against Trametes versicolor. Additionally, the hybrid foams exhibited good and competitive properties. These low-density foams enabled by the excellent bonding capability of CNFs could thus be potentially used to provide antifungal resistance as well as acoustic and thermal insulation. [Display omitted] • Foam forming method was used to develop ultra-low density TMP/CNF foams. • Anionic (SDS) and cationic (CTAB) foaming agents were used in foam formulations. • TMP/CNF foams provided antifungal resistance, acoustic and thermal insulation. • Hybrid foams from different fibers showed good and competitive properties. • Water stability and foams' strength were improved with CNF and solid contents. [ABSTRACT FROM AUTHOR]

A more efficient application of a dry strength agent (DSA) was investigated to improve the strength of thermomechanical pulp (TMP) blended paper. Strength improvement by DSA application was more effective for hardwood bleached kraft pulp (Hw-BKP) than TMP. The degree of strength improvement of DSA further increased with the increasing degree of refining of Hw-BKP. The strength of the paper was decreased by the fines fractionation of TMP, but the strength improvement efficiency of DSA for the fines fractionated TMP increased. In order to increase the strength of TMP mixed paper using DSA, it is expected that DSA should be adsorbed only to Hw-BKP with high strength improvement efficiency, not TMP fines. When the DSA was mixed with Hw-BKP before contact with other stocks, it was confirmed that the effect of improving the strength by the DSA is the best. The strength improving effect increased as TMP fines were removed. Therefore, to improve the strength of the paper containing TMP in Hw-BKP by adding a DSA, it is preferable to selective apply the DSA to Hw-BKP while blending only the fibers of TMP by fractionation. [ABSTRACT FROM AUTHOR]

Compression molded composites were prepared through a water‐assisted mixing of an aqueous suspension of poly(ethylene‐co‐acrylic acid), additive, and pulp fibers [thermomechanical pulp (TMP) or dissolving pulp (DP)]. The lubricating additives used were magnesium stearate (MgSt) and molybdenum disulphide (MoS2). The composite materials had dry pulp contents ranging from 30 to 70 wt% and 5 wt% additive relative to the weight of the pulp. The adsorption of the additives onto the fibers was confirmed by scanning electron microscopy and energy dispersive X‐ray analysis. DMA showed that MgSt and MoS2 gave similar interphase properties for the TMP samples at all loading contents, but the combination of MgSt and MoS2 improved the overall properties of the DP‐based composites. The tensile modulus, at 70 wt% fiber content (TMP or DP), increased compared to the matrix by a factor of 6.3 and 8.1, without lubricants, and by a factor of 8 and 10.7, with lubricants, respectively. The increase in melt viscosity observed for the lubricated samples was greater for the TMP‐based samples containing MoS2. At a lubricant content of 5 wt%, in 30 wt% TMP, the MoS2 behaved as both a lubricant and compatibilizer. [ABSTRACT FROM AUTHOR]

The biomass resources oil palm empty fruit bunch (EFB) and sugarcane bagasse, which are residues from the palm oil and sugar industries, continue to be investigated for more applications. With increasing concern for the environment, cleaner production has been a worldwide aim of researchers. In this study, thermomechanical pulp (TMP) from EFB and sugarcane bagasse was prepared with disc refining after steam pretreatment of the raw materials. Afterwards, refining and handsheet properties of TMP using various percentages of unbleached soda bagasse pulp (USBP) were studied. Fiber characterizations and handsheet properties showed that pulp of acceptable quality was obtained via thermomechanical pulping. Moreover, energy consumption during PFI refining of EFB TMP was higher than that of bagasse TMP. Physical properties were further enhanced through introduction of USBP. The results firmly support the feasibility of cleaner thermomechanical pulping of EFB and sugarcane bagasse. [ABSTRACT FROM AUTHOR]

The feasibility of incorporating purified kraft lignin, at different concentrations ranging from 5 to 29%, into fiberboards made from corn residues was studied. The lignin was obtained from black liquor, which is a residue of the paper industry. Corn stalk raw material and its thermomechanically produced fiber were characterized in terms of their chemical composition. The physical and mechanical properties of the resulting fiberboards were evaluated. The fiberboards produced following a wet process had good mechanical and water resistance properties that satisfied the requirements of the relevant standards. In addition, a Life Cycle Thinking (LCT) approach suggested that lignin-based fiberboards are environmentally preferable than those based on thermosetting resins.

TEMPO-oxidized thermomechanical pulp (TMP) prepared at low-oxidized and highly oxidized levels was compared with untreated TMP to observe the advantage of each pulp on paper properties. While the low oxidized pulp and non-oxidized pulp gave similar properties, highly oxidized TMP significantly increased tensile strength and decreased tear strength. Brightness was negatively affected by oxidation. In order to improve the paper optical properties, the use of a conventional mineral filler retention system was studied, using clay as filler. The high charge induced by the oxidized pulp significantly modified the pulp retention behavior. Moreover, paper made from pulp containing oxidized pulp and clay presented considerably better tensile strength with a loss in tear resistance for the same brightness target, which could be interesting for some paper applications. [ABSTRACT FROM AUTHOR]

4-Acetamido-TEMPO-mediated oxidation was carried out on thermomechanical pulp (TMP) to further investigate the extraction components of the oxidized pulp. Successive extractions on non-oxidized, bleached and oxidized TMP have shown that components were easier to extract from the oxidized pulp. The pulp lignin content demonstrated that the highest content of lignin was removed by sodium hydroxide extraction. Moreover, more than two times the amount lignin was extracted from oxidized pulp compared to non-oxidized pulp. The measured carboxylic groups showed that the highest amounts of the oxidized components were removed after the first extraction. However, after each extraction, reduced but still significant amounts of carboxylic groups were present in the extracted material. Thermogravimetric analysis showed that 4-acetamido-TEMPO oxidation treatment induced a decrease in the fibre degradation temperature caused by a weakening in the fibre structure. The results also demonstrated that some components of the highly oxidized pulp were more easily dissolved because of the critical extraction conditions. Furthermore, the recovered precipitate in the extraction solvent had different XPS characteristics according to the initial pulp treatment. The analysis of the oxidized TMP precipitate showed that the precipitate from hot water extraction was the most highly oxidized, while the precipitate from sodium hydroxide extraction approached pure lignin characteristics. [ABSTRACT FROM AUTHOR]

During mechanical defibration of wood, a minor fraction of the wood mass is dissolved in the process water. These dissolved substances represent an extra energy demand when they are treated in the mill's wastewater treatment plant. Galactoglucomannan, the main hemicellulose in spruce, can be recovered from thermomechanical pulp mill process water by a process based on microfiltration (MF) and ultrafiltration (UF). The purpose of this work was to study the scale-up of the process from laboratory scale to continuous industrial scale. MF was first studied in the laboratory, and then combined with UF in a continuous pilot process on-site at a pulp mill. The data obtained were used to estimate the cost of the membrane processes for galactoglucomannan recovery which was found to be about €1160 per ton hemicelluloses. [ABSTRACT FROM AUTHOR]

In hydrogen peroxide bleaching of thermomechanical pulp (TMP), reaction temperature and time are the main factors that can improve the bleachability of pulp fibers. However, high temperatures can induce some problems such as cellulose degradation, yield loss, low fiber strength, and high environmental load. These negative effects of high temperature are mainly caused by radicals formed from the decomposition of hydrogen peroxide. To avoid the adverse effects of high temperature, we used two-step thermal treatments during hydrogen peroxide bleaching of TMP. The temperatures used in the two-step thermal treatments were 80 and 45 ˚C for a total bleaching time of 1 hour. In H2O2 bleaching of TMP, two-step thermal treatments were found to have had positive effects on the optical and physical properties of the pulp. The ISO brightness of the pulp bleached by two-step thermal treatments with hydrogen peroxide was identical to that of pulp bleached by conventional hydrogen peroxide bleaching. The post color number (PC number) of TMP was sharply increased after bleaching at 80 ˚C for 40 minutes. The post color number of TMP bleached by two-step thermal treatments is lower than that of TMP bleached by a one-step thermal treatment. The zero-span tensile index was also improved by two-step thermal treatments.

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In this work, the thermomechanical pulp of Pinus massoniana was pretreated with a NaOH/thiourea/urea aqueous solution to promote fiber bonded area and to increase paper strength. The effects of pulp concentration, alkali dosage, dipping time, and freezing time were evaluated through single factor experiments. The optimum conditions were found to be 15% pulp consistency, 8% NaOH, a dipping time of 15 min, and a freezing time of 60 min. Under these conditions, the paper tensile and burst index of treated pulp increased nearly 100%, and the bulk also was reduced by 10%, but there were no significant effects on folding.

Thermomechanical pulp (TMP) is used for fiber production in binderless boards industries. Milled wood lignin (MWL) and enzymatic mild acidolysis lignin (EMAL) isolated from raw material and from binderless boards (BB) were comparatively analyzed to investigate the effects of chemical changes on the bonding performance in BB. The results showed that acid-insoluble lignin of the BB were increased during the sodium silicate solution pretreatment after hot-pressing. The lignin fractions obtained were characterized by gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) spectroscopy, and 1H-13C correlation heteronuclear single-quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy. Results showed that 31.1% of EMAL (based on Klason lignin) with low molecular weight (Mw=1630 g/mol) was isolated from the BB. The increased total phenolic OH groups (3.97 mmol/g) of EMAL from sodium silicate solution pretreated BB indicated that there was degradation of lignin and cleavage of lignin-carbohydrate linkages during hot-pressing. In addition, the content of β-O-4' aryl ether linkages of EMAL from the BB increased to 69.2%, which was higher than that of the untreated sample (60.1%). It was found that S units (syringyl-like lignin structures) were preferentially condensed by hot pressing over G (guaiacyl-like lignin structures) units, and the S/G ratio increased after the hot-pressing process.

This research identified suitable conditions to fabricate pulp fibers for paperboards and medium density fiberboards (MDF) from the bagasse of sugarcane ( Saccharum officinarum ) and the empty fruit bunch (EFB) of oil palm ( Elaeis guineensis ). First, the effects of chemical pretreatments at 121 °C and pressurized refining under steaming conditions were studied in regards to the thermomechanical pulps. The optimal conditions to achieve the highest paper strength properties of the EFB pulp involved pretreatment with 2% NaOH for 2 h and refining at 0.7 MPa of pressure at 165 °C. The sugarcane bagasse (SB) pulp properties could not be improved by chemical pretreatment, while the EFB pulp properties clearly benefited from such pretreatment. Second, the effects of dry and wet blowing methods after pressurized refining on the fiber properties were examined. The strength properties of the half-dried SB and EFB pulps with 55% solid content were slightly higher than those of their wet counterparts. These results clearly suggest that SB and EFB can be promising refined fibers for paperboard and MDF preparation. Third, MDF was made from dried EFB refined fibers with 92% solid content by dry processing, and suitable properties for actual use were obtained. [ABSTRACT FROM AUTHOR]

Thermomechanical pulp (TMP) was fabricated from the empty fruit bunch (EFB) of oil palm ( Elaeis guineensis ) by using a laboratory-scale pressurized refiner. The EFB TMP was separated by screens (850, 355, and 180 μm openings) into four fractions. Pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) indicated analogous chemical features of lignin in the TMP fractions by determining eight pyrolysis products from its syringyl (S) and guaiacyl (G) types. The amount of each pyrolysis product was quantitatively determined through a calibration line obtained by the conversion factor of the main ion intensity to an authentic compound weight. Moreover, S/G molar ratios obtained by Py-GC/MS provided a good correlation with the syringaldehyde/vanillin (S a /V a ) molar ratios obtained by nitrobenzene oxidation for raw EFB material and some hardwoods. The TMP fabrication process slightly changed the lignin structure. Py-GC/MS was found to be a reliable analytical method for the characterization of lignin in EFB TMP. [ABSTRACT FROM AUTHOR]

Hot-water extraction of hemicelluloses, especially galactoglucomannans, from fractions of ground spruce wood with different particle sizes was studied at 170°C with extraction times up to 60 min. Extraction of spruce sapwood, heartwood, and thermomechanical pulp (TMP) was also compared at 160 to 180°C. Static batch extractions were carried out in an accelerated solvent extractor (ASE). The extracted hemicelluloses were characterized by sugar unit analysis and determination of acetyl groups and molar masses. The particle size significantly affected the extraction of ground wood. The total extraction yield, as well as the yields of hemicelluloses and monosaccharides, was the highest from the finest ground wood fraction (< 0.1 mm). The release of acetic acid, average molar mass of extracted hemicelluloses, and end-pH of the extracts were also dependent of the particle size, although to a lower extent. Irrespectively of the ground wood particle size, the yield of hemicelluloses reached a plateau after 40 min extraction at 170°C. The results indicate that extraction of hemicelluloses is limited mainly by the diffusion in the fiber wall, and for coarse wood shives also by the mass transfer in the wood matrix. There were only small differences in the hot-water extraction yields of hemicelluloses from spruce sapwood, heartwood, and TMP, considering both poly- and monosaccharides.

In order to improve the properties of thermomechanical pulp (TMP), the influences of the TEMPO (2,2,6,6-tetramethylpiperidyl-1-oxyl radical)-mediated oxidation on recycled TMP properties were investigated, and the impacts of recycling process on TEMPO-mediated oxidized TMP properties were studied as well. The results showed that TEMPO-mediated oxidation is an effective way to enhance the recycled TMP inter-fiber bonding dependent properties due to the introduction of carboxylic acid groups onto pulp, while the oxidation had some negative impacts on the tear index, zero span tensile index, and brightness. The oxidation-recycling (O-R) process had remarkable adverse impacts on TMP compared with the recycling-oxidation (R-O) process. The tensile, burst, tear strengths, as well as the zero-span tensile strength dropped sharply when oxidized TMP was recycled, and the physical strength properties decreased with the increasing recycling times. The opacity was improved after the O-R treatment, although the O-R treatment had an adverse impact on the pulp brightness.

A layer-by-layer (LbL) self-assembly technique using polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) was employed to build up polyelectrolyte multi-layers on pretreated thermomechanical pulp fibres. These pretreated fibres previously had been oxidized by means of a 4-acetamido TEMPO-mediated process in order to create carboxylic functions. These allow the subsequent formation of amide bonds between PAH and fibres. X-ray photo-electronic spectroscopy (XPS) analyses confirmed the formation of amide bonds between the carboxylic function on the fibres and the primary amine function of the PAH. Besides, the surface charge intensity of the coated fibres was determined by measuring the zeta potential after each treatment step.

For the thermomechanical pulping (TMP) process both wood chip quality and the refining process have important effects on the resulting pulp and paper quality. Properties of wood raw material give a framework for final pulp properties. During TMP refining the specific energy consumption and refining intensity strongly impact fibre and pulp qualities. Increasing specific energy consumption benefits the development of fibres and improves their properties. However, high intensity refining tends to shorten the fibres and produces more fines content when compared with low intensity refining. This review focuses on the influence of key variables of chip qualities and the refining process on TMP pulp and paper qualities.

The purpose of this study is to develop an analytical method to quantify the nitrogen present at the surface of paper by using X-ray photo-electronic spectroscopy (XPS). A sample of softwood thermomechanical pulp (TMP) was treated with a cationic starch containing primary amines, while another one was treated with a cationic polymer containing quaternary amines. We also grafted monomers containing a quaternary amine to the fiber. Sheets were prepared and analyzed by XPS. The technique used allowed us to identify the type of amine and to give a semi-quantitative evaluation.

The purpose of this work was to improve the quality of jack pine TMP long fibers, particularly with respect to the strength properties, by alkaline peroxide treatment. This paper reports the chemical characteristics of the treated long fibers and the spent liquors originating from various treatments. It was observed that, in comparison with hydrogen peroxide, the alkalinity of the treatment solutions had a greater influence on most fibre characteristics and spent liquor properties.

[Display omitted] • Facile, scalable production of hyperbranched wood fiber using mild disc milling. • Air dried foam assembled from hyperbranched wood fiber with no binder use. • Sub-fibrous structures of wood fiber improved foam's mechanical properties. • Natural, high melting point wax allowed enhanced water/moisture repellency. • Woody foam demonstrated better thermal insulation than commercial glass fiber mat. Demand for sustainable building thermal regulation is driving the development of low carbon-intensive, renewable, and safe-to-use materials to substitute the dominant synthetic polymers and inorganic mats. This study proposes a novel mild mechanical pretreatment strategy to fabricate high-performance, self-strengthening thermal insulation board in a low cost and scalable approach from chemi-thermomechanical pulp (CTMP), a type of high-yield wood pulp. CTMP fibers, after subject to a short period of disc milling, were found to gain abundant sub-fibrous structures at multiple scales. After foaming and air-drying, such micro-fibrillated fibers (MF-CTMP) formed robust, binder-free foam under capillary force with remarkedly stronger physical entanglement between fibers compared to that of pristine CTMP, achieving 3.7 folds Young's modulus, 2.9 folds ultimate stress, and 1.9 folds toughness with respect to the latter. Palm wax coating further provided a sustainable hydrophobic protection for the foam (contact angle of ∼ 110°). The high porosity and structural tortuosity endowed the hydrophobic MF-CTMP foam with excellent thermal insulation property (thermal conductivity of 33.1 ± 2.3 mW/(m∙K)), demonstrating significantly better performance than a commercial glass fiber thermal insulator. Compared to other lignocellulosic boards prepared using freeze-drying or supercritical drying operations, the hydrophobic MF-CTMP foam represents a novel low cost, binder-free, and scalable technology for commercial sustainable thermal insulation applications. [ABSTRACT FROM AUTHOR]

Hemicelluloses dissolved in thermomechanical pulp (TMP) mill process streams can be used to manufacture high-value-added products. The molecular mass of the dissolved hemicelluloses is about 10 kDa. In some applications, it would be beneficial with larger molecules. It was therefore investigated whether it is possible to increase the size of hemicelluloses isolated by microfiltration and ultrafiltration from TMP process water using enzymatic treatment with laccase. No significant increase of the size of hemicelluloses was achieved, probably due to only a small percentage of lignin carbohydrate complexes in the process water. The molecular mass of lignin increased however markedly from a peak molecular mass of 1 kDa to about 60 kDa. Diafiltration was used to purify large molecules after the enzymatic treatment. Low-molecular-mass sugar and lignin molecules in the diafiltration permeate were concentrated by nanofiltration. The retention of sugars and lignin was about 98% during nanofiltration to a volume reduction of 80%. Average flux during nanofiltration was 49 l/m 2 h. [ABSTRACT FROM AUTHOR]

The feasibility of employing chemical methods for enhancement of cellulose-based materials is dependent on the availability, price, and green index of the modifying agent. This study details the use of iodomethane, an inexpensive organo halide, to increase the hydrophobicity of thermo mechanical (TMP) samples, which renders them better structural elements for composite materials. For this system, we studied the influence of various concentration of iodomethane, concentration of caustic, and reaction time. Infrared spectroscopy suggested reaction of the organo halide with the hydroxyl groups of cellulose and lignin components of TMP. Pulp samples treated for 4 h or at low caustic concentration showed the least improvements plausibly due to pulp degradation or poor pulp swelling, respectively. On the other hand, pulp treated at 3 h using high concentrations of caustic were characterized with surfaces that were more hydrophobic. Thus, this study outlines a fast and organic solvent-free (clean up) method that can be used to enhance pulp samples for composite applications. [ABSTRACT FROM AUTHOR]

A method is proposed for producing fatty acid esters of thermomechanical pulp (TMP) using fatty acids of intermediate chain length (C6-C12). The end objective is to use a stream of fatty acids produced via refining tall oil from Alberta's pulping mills. Depending on the degree of modification, these treated materials can serve either as reinforcement or as copolymers in composite applications. The effect of reaction conditions—reaction time, reaction temperature, fatty acyl concentration, and fatty acid chain length—on the degree of substitution of the pulp samples was studied. The reaction conditions were applied for each fatty acyl chloride and the pulp samples were characterized using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, force tensiometry, time-of-flight secondary ion mass spectroscopy, atomic force microscopy, and thermal gravimetric analysis. The degree of substitution (DS) plateaued after two hours at a concentration of 0.25 M of hexanoyl chloride. These conditions were used for the other systems studied. The esterification of the pulp samples was heterogeneous as evident from both the AFM and SIMS images, because of the presence of lignin on the surface. Nevertheless, based on adhesion forces measured using AFM, the surface of the modified pulp samples was less polar. This was also confirmed via contact angle measurements. Also, the changes in chemical functionality were studied using FTIR and XPS with the appearance of peaks characteristic of C˭O (esters) and an increase in intensity of the alkyl shifts, respectively. Finally, it was found that esterification significantly improved the thermal properties of the pulp samples. [ABSTRACT FROM PUBLISHER]

Galactoglucomannan is the major hemicellulose in process water from thermomechanical pulping of spruce. The recovery of hemicelluloses from this process water would both reduce the load on pulp mill water treatment plants and yield a biopolymer suitable as a raw material for renewable products. One method of recovering these hemicelluloses is two-stage filtration employing microfiltration to remove large contaminants, such as suspended matter and colloidal extractives, followed by ultrafiltration to concentrate and purify the hemicelluloses from low molecular mass contaminants. This investigation shows that a microfiltration membrane with a pore size of 0.1 μm removes colloidal extractives while still maintaining a high amount of high molecular mass hemicelluloses in the microfiltration permeate. The removal of extractives resulted in an increase in the initial flux during the subsequent ultrafiltration step from 90 L/m 2 h to over 200 L/m 2 h. [ABSTRACT FROM AUTHOR]

H 2 O 2 was used in the final stage of a multistage bleaching process to increase ISO brightness by 2–3%, because of the poor selectivity and bleachability. However, concerns about the environmental load of the bleaching process have led to the efficient use of oxygen-derived compounds, with a concomitant decrease in the quantity of chlorine-derived compounds consumed. In this study, thermomechanical pulp (TMP) and unbleached kraft pulp (UKP) were bleached with H 2 O 2 and ultrasonicated in order to increase the bleaching efficiency, and the effects of some bleaching conditions such as treatment time, treatment concentration, and temperature were determined. The best bleaching efficiency of pulp was obtained using H 2 O 2 with ultrasonication (at 20 kHz) of the pulp mixture at 45 °C for 30 min. The ISO brightness of the bleached pulp increased up to 1.9%, although the bleached pulp yield was slightly reduced to 1.5%. Magnesium sulfate was used as a bleaching stabilizer to increase the bleached pulp yield and viscosity. As a result, the bleached pulp yield and viscosity increased by 2.1% and 10%, compared with fully bleached pulp at the end of the process, respectively, despite a decrease in ISO brightness. [ABSTRACT FROM AUTHOR]

A new concept for topochemical activation of mechanical pulp fibres was investigated. The activation concept was based on attachment of precursors of peracids onto the surface of the fibres prior to hydrogen peroxide bleaching. The activators used in this work were: tetraacetylethylenediamine (water soluble), lactose octaacetate (LOA, colloidal particles, and low water solubility) and sucrose octaacetate (partially soluble in water). LOA showed promising results for application in the surface activation concept due to attachment of colloidal particles on the outmost surface of the fibres, simultaneously contributing to a brightness increase. Surface coverage by lignin on fibres had decreased after the bleaching process with activators, which was detected by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. [ABSTRACT FROM AUTHOR]

Darkening of the fines and fiber fraction of peroxide-bleached thermo-mechanical pulp (TMP) was studied on a laboratory scale using a device that simulates the short circulation of a paper machine. Selected chemicals were dissolved in the circulation water to study the effect of different cations and anions. Ferrous ions darkened the fines and fiber fraction by increasing the light absorption. It is very important to keep the iron content of the pulp and white water as low as possible because even low contents of iron have a negative effect on the brightness of produced paper. Also, chloride ions decreased the brightness by increasing the light absorption of the fines and fiber fraction. Calcium ions increased both the light absorption and light scattering of the fines fraction. The increased light absorption dominated and the brightness decreased. Calcium chloride is used very commonly as a model chemical for calcium ions in laboratory tests, but the use of it is not recommended, if the darkening phenomena are studied, because chloride ions decrease the brightness. Aluminum ions increased the brightness of the fines fraction by increasing the light scattering. Manganese, sodium, sulfate, or carbonate ions did not affect the optical properties. [ABSTRACT FROM AUTHOR]

This work explores the use of mechanical (MP), thermomechanical (TMP), and chemi-thermomechanical (CTMP) pulps from orange tree pruning fibers (OPF) as reinforcing elements of polypropylene (PP) composites. Due to the nature of the natural fibers, the use of a coupling agent is needed to attain a good interface and to prevent fiber slippage from the matrix. The main objective of the present work was to investigate the orientation factor, the interfacial shear strength, and the intrinsic strength of the OPF. Coupled and non-coupled composites were formulated and tested, optimizing the coupling agent content with the objective of maximizing the tensile strength of the composites. Hirsch and Kelly-Tyson models and the Bowyer-Bader methodology were used to compute the micromechanic properties. The contribution of subcritical, supercritical fibers, and matrix were also calculated. [ABSTRACT FROM AUTHOR]

Abstract: The influences of various factors in 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation on delignification, lignin aromatic ring and side chain structures of thermomechanical pulp (TMP) were investigated. The results indicate neither TEMPO nor NaBr alone can provoke changes in lignin content or lignin structure under weakly alkaline conditions. However, NaClO and NaClO–NaBr were able to remove lignin effectively, causing remarkable changes in lignin structure. Delignification was promoted when TEMPO was used with NaBr and NaClO. In contrast to NaClO alone, an additional 15% lignin was removed when TEMPO-mediated oxidation system was used, but it did not induce further changes on lignin structure. Increased doses of oxidizing agent and reaction time also improved the oxidation of cellulose and delignification, but they did not have a significant impact on lignin aromatic and side chain structures. [Copyright &y& Elsevier]

Abstract: Bleached thermomechanical pulp (TMP) has been applied in the production of newsprint and supercalendered (SC) paper or other paper products. Recent studies on the alkaline peroxide bleaching with magnesium-based alkalis indicated that the bulk and optical properties can be improved, and effluent load can be reduced. In this work, MgO was partially used in alkaline peroxide bleaching process of pine (Pinus massoniana) TMP to investigate the effect of MgO substitution for NaOH on the pulp properties and effluent characteristics. The present research showed that partial substitution of MgO for NaOH could decrease the dissolution of chemical components in pulp fibers, thus, improving the pulp yield and decreasing the effluent load. When the substitution percentage of MgO for NaOH increased from 0% to 50% at 3.5% alkali charge, the bulk of the bleached pine TMP increased from 3.45cm3/g to 3.69cm3/g, while the opacity was improved from 84.7% to 89.1%, the cationic demand and CODCr of the effluent decreased by 31% and 22%, respectively. However, the MgO substitution had decreased the brightness and tensile index of the bleached TMP. [Copyright &y& Elsevier]

A layer-by-layer (LbL) self-assembly technique using polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) was employed to build up polyelectrolyte multi-layers on pretreated thermomechanical pulp fibres. These pretreated fibres previously had been oxidized by means of a 4-acetamido TEMPO-mediated process in order to create carboxylic functions. These allow the subsequent formation of amide bonds between PAH and fibres. X-ray photo-electronic spectroscopy (XPS) analyses confirmed the formation of amide bonds between the carboxylic function on the fibres and the primary amine function of the PAH. Besides, the surface charge intensity of the coated fibres was determined by measuring the zeta potential after each treatment step. [ABSTRACT FROM AUTHOR]

Micro- and nanocelluloses are typically produced using intensive mechanical treatments such as grinding, milling or refining followed by high-pressure homogenization to liberate individual nano- and microcellulose fragments. Even though chemical and enzymatic pretreatments can be used to promote fiber disintegration, the required mechanical treatments are still highly energy consuming and very costly. Therefore, it is important to understand the kinetics and factors affecting the disintegration tendency of cellulose. In this study, the disintegration tendency of three different wood cellulose pulps with varying chemical composition processed in a PFI mill was examined by analyzing the fractional composition of the microparticles formed. The fractional compositions of the microfibrils and microparticles formed were measured with novel analyzers, which fractionated particles using a continuous water flow in a long tube. The hydrodynamic fractionators used in this study gave valuable information about different size of particles. Results showed that the amount of lignin and hemicelluloses clearly affected the kinetics and the mechanics of cellulose degradation. The P and S1 layers were peeled off from the Kraft fibers, causing the S2 layer to be cropped out. The thermomechanical pulp (TMP) fibers were first degraded by comminution and delamination from the middle lamella and the primary wall. As the refining process progressed, the fibers and fiber fragments began to unravel. Surprisingly, the semi-chemical pulp (SCP) fibers degraded more like Kraft fibers than TMP fibers despite their high lignin and extractive content. [ABSTRACT FROM AUTHOR]

The driving force for pulp and paper industry is to develop new technologies with less impact to the environment. In this context, the successful approach in the present paper was the substitution of sodium hydroxide during peroxide bleaching of thermomechanical pulp (TMP) by magnesium hydroxide or magnesium carbonate. Looking at brightening development, thioacidolysis showed that Mg-based processes eliminated less coniferaldehydes than NaOH-based bleaching. Moreover, 19F NMR analysis showed slightly more residual quinone in lignin isolated from NaOH-based bleached pulp than lignin extracted after Mg-based bleaching. Replacing NaOH by Mg-based compounds affected the strength properties of the paper: tensile index was 10% lower than conventional bleached paper, probably due to Mg2+ adsorption on the acid groups of fibers. However, the brightness reversion of Mg-based bleached paper decreased by about two ISO points during photoageing under sunlight. X-ray photoelectron spectroscopy supported the conclusion that Mg-based bleaching caused less re-deposition of lignin and extractives onto the fiber surface compared to the conventional process resulting in less light-induced yellowing. [ABSTRACT FROM AUTHOR]

For the thermomechanical pulping (TMP) process both wood chip quality and the refining process have important effects on the resulting pulp and paper quality. Properties of wood raw material give a framework for final pulp properties. During TMP refining the specific energy consumption and refining intensity strongly impact fibre and pulp qualities. Increasing specific energy consumption benefits the development of fibres and improves their properties. However, high intensity refining tends to shorten the fibres and produces more fines content when compared with low intensity refining. This review focuses on the influence of key variables of chip qualities and the refining process on TMP pulp and paper qualities. [ABSTRACT FROM AUTHOR]

Abstract: Several valuable substances are released from wood during the production of thermomechanical pulp. These substances can be isolated and purified for use as value-added chemicals. The hemicellulose galactoglucomannan (GGM) has attracted a great deal of interest because of its possible applications as an oxygen barrier film in packaging materials, as a hydrogel in biomedical products and as an emulsion stabilizer in food and feed. In order to exploit GGM in pulp mill process water, it must be recovered at a high concentration and high purity. The first step in the purification process is the separation of GGM and dispersed substances. In this work, the influence of membrane pore size, cross-flow velocity and backpulsing on membrane performance during the microfiltration of thermomechanical pulp process water was investigated. The flux of 0.4 and 0.8μm membranes was lower than the flux of a 0.2μm membrane, and it was not possible to recover the pure water flux of the 0.4 and 0.8μm membranes. Increased cross-flow velocity and backpulsing had a positive effect on the flux, but only a minor influence on the retention. The mean molecular mass of GGM in the process water was 9kg/mol. The retention was therefore expected to be <10%. However, the retention of GGM was >50%, irrespective of the operating conditions. [Copyright &y& Elsevier]