Surface Energy and Lewis Acid-base Characteristics of Lignocellulosic Fibers upon Modification by Chemical Vapor Deposition of Trichloromethylsilane: An Inverse Gas Chromatography Study

Supplemental data for this article can be accessed on the publisher’s website at http:// dx.doi.org/10.1080/02773813.2018.1454961The surface of a thermomechanical pulp (TMP), containing 26 wt% of lignin, was modified by silanization with trichloromethylsilane (TCMS) via chemical vapor deposition, and thoroughly analyzed for its physicochemical properties by inverse gas chromatography (attenuated total reflection-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy being used as complementary tools). For a 2-min TCMS-treated TMP, a decrease of the dispersive component of the surface energy from 38 to 14 mJ m−2 (at 40°C), and, at the same time, an increase of the Lewis acidic and Lewis basic characters were found. The surface of this sample, modified in a high extent, was similar to that of a bleached kraft pulp (<0.1 wt% of lignin) subjected to the same silanization process, which is suggested as being due, in both cases, to the formation of a methyl-silica coating on the fiber’s surface. The new silanized fibers obtained from cheap TMP can be used for the production of a new generation of biocomposites with a variety of matrices

New polyoxometalate-functionalized cellulosic fibre/silica hybrids for environmental applications

Cellulosic fibre/silica hybrid materials functionalized with Keggin-type polyoxometalates ([PV2Mo10O40]52, [PVMo11O40]42, ([PMo12O40]32 or [PW12O40]32) were prepared by a sol–gel method at room temperature. The novel materials are composed of ca. 56 wt% of polysaccharides, ca. 37 wt% of propylamine-modified silica, 2 wt% of polyoxometalate, and 5% of hydration water. The silica network of these hybrids exhibits relatively high degree of condensation being distributed mainly on the surface of the cellulosic fibres as a dense film. The functionalization of silica with polyoxometalates via electrostatic interactions with protonated propylamino groups of modified silica was unambiguously confirmed. Despite their high silica content cellulose/silica hybrids retained basic cellulosic pulp properties—supramolecular and fibrous structure, porosity, relatively low density, etc. The novel bio-based material functionalized with 2% of [PVMo11O40]42 shows particularly high activity towards the oxidation of volatile organic compounds (VOCs) present in urban air thus anticipating future environmental applications.publishe

Towards a natural classification : the taxonomy and evolution of Xanthorrhoea

The ability to increase the filler content of paper without significantly sacrificing its mechanical strength is of high interest for papermakers. In this work, three samples of ground calcium carbonate (GCC), differing in size and in brightness, modified with silica via the sol-gel method, were used as fillers in papermaking. Handsheets were produced using a eucalyptus kraft pulp furnish and with a filler amount near 20%. It was found that not only were the strength properties of the handsheets produced with the modified GCCs always significantly better than those obtained with the unmodified GCCs (e.g., the tensile index exhibited improvements of 16 to 20%), but bulk also was increased (by 7 to 13%). Some decreases in the light scattering and opacity values were noted when using the modified GCC, but the brightness was roughly the same. The enhanced fiber-to-filler bonding may be attributed to the hydrogen bonding between the cellulosic fibers and the hydroxyl groups of the silica coating the calcium carbonate particles

Impact of bacterial cellulose on the physical properties and printing quality of fine papers

Bacterial nanocellulose (BNC), due to its inherent nanometric scale and strength properties, can be considered as a good candidate to be used in papermaking. This work explored the possibility of using it in the production of fine paper as a wet-end component and for the paper coating. Filler-containing handsheet production was performed with and without the presence of common additives typically used in the furnish of office papers. It was found that, under optimized conditions, BNC mechanically treated by high-pressure homogenization could improve all the evaluated paper properties (mechanical, optical and structural) without impairing the filler retention. However, paper strength was improved only to a small extent (increase in the tensile index of 8% for a filler content of ca. 27.5%). On the other hand, when used at the paper surface, remarkable improvements in the gamut area of >25% in comparison to the base paper and of >40% in comparison to only-starch coated papers were achieved for a formulation having 50% BNC and 50% of carboxymethylcellulose. Overall, the present results highlight the possibility of using BNC as a paper component, particularly when applied at the paper substrate as a coating agent aiming at improving printing quality.Fundacão para a Ciência e a Tecnologia (FCT), Portugal is acknowledged by SFRH/BDE/108095/2015 grant and Strategic Research Centre Project (UIDB/00102/2020). This work was also carried out under the Project Inpactus - innovative products and technologies from eucalyptus, Project N.º 21874 funded by Portugal 2020 through European Regional Development Fund (ERDF) in the frame of COMPETE 2020 nº246/AXIS II/2017info:eu-repo/semantics/publishedVersio

On the morphology of cellulose nanofibrils obtained byTEMPO-mediated oxidation and mechanical treatment

The morphological properties of cellulose nanofibrils obtained from eucalyptus pulp fibres wereassessed. Two samples were produced with the same chemical treatment (NaClO/NaBr/TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation), but distinct mechanical treatment intensities duringhomogenization. It was shown that the nanofibrils production yield increases with the mechanicalenergy. The effect of mechanical treatment on the yield was confirmed by laser profilometry of air-driednanocellulose films. However, no significant differences were detected regarding the nanofibrils widthas measured by atomic force microscopy (AFM) of air-dried films. On the other hand, differences in sizewere found either by laser diffraction spectroscopy or by dynamic light scattering (DLS) of the cellulosenanofibrils suspensions as a consequence of the differences in the length distribution of both samples.The nanofibrils length of the more nanofibrillated sample was calculated based on the width measured byAFM and the hydrodynamic diameter obtained by DLS. A length value of ca. 600 nm was estimated. TheDLS hydrodynamic diameter, as an equivalent spherical diameter, was used to estimate the nanofibrilslength assuming a cylinder with the same volume and with the diameter (width) assessed by AFM. Asimple method is thus proposed to evaluate the cellulose nanofibrils length combining microscopy andlight scattering methods

Filmes de Celulose Nanofibrilada com Incorporação de Minerais como Substitutos de Plásticos em Embalagens Alimentares: Potencialidades e Dificuldades

Celuloses nanofibriladas (CNF) são nanomateriais com propriedades promissoras para produção de embalagens alimentares, sendo substitutos lógicos de polímeros de base petroquímica, especificamente plásticos. Contudo, estes materiais apresentam algumas limitações, como o seu elevado custo. A combinação de CNF com minerais argilosos representa uma excelente abordagem para a produção de materiais de elevado valor acrescentado com custos aceitáveis, possibilitando ainda a melhoria de algumas propriedades dos materiais, como por exemplo o efeito barreira a gases. Para a produção de filmes compósitos podem ser seguidas duas estratégias: evaporação de solvente ou filtração seguida de prensagem a quente. Os filmes obtidos por filtração apresentam propriedades mecânicas superiores às dos obtidos por evaporação de solvente e são preparados mais rapidamente. Assim, esta técnica apresentase como a mais apropriada e eficiente para a produção de filmes compósitos com boas propriedades mecânicasN/

Filmes de celulose nanofibrilada com incorporação de minerais: uma nova geração de materiais para embalagens alimentares e eletrónica impressa

O trabalho de investigação foi realizado no âmbito do projeto “FILCNF-New generation of composite films of cellulose nanofibrils with mineral particles as high strength materials with gas barrier properties” (PTDC/QUI-OUT/31884/2017, CENTRO 01-0145-FEDER-031884), financiado pelo Programa Operacional Regional do Centro na sua componente FEDER e pela Fundação para a Ciência e Tecnologia (FCT). Agradece-se ainda ao RAIZ pelo fornecimento da pasta branqueada de Eucalyptus globulus e pelo acesso ao homogeneizador de alta pressão, assim como ao centro de investigação CIEPQPF (UIDB00102/2020) pelas condições disponibilizadas.info:eu-repo/semantics/publishedVersio

New modified filler obtained by silica formed by sol–gel method on calcium carbonate

This study focus on the modification of the particles of precipitated calcium carbonate (PCC) with silica formed in situ by sol–gel method. The new materials were characterized by several spectroscopic, analytical and microscopic techniques. A dense film of highly branched silica was formed at the surface of the scalenohedral PCC crystals. The amount of silica deposited at the PCC surface, as determined by thermogravimetric analysis, reached up to 25 wt% under appropriate experimental conditions. Particle size distributions obtained by laser diffraction spectroscopy of the new modified PCC’s were close to the distribution of the original PCC, even considering that some variation in the average size of the particles was noted. This result is of great interest regarding the application of these materials, for instance, as fillers in the paper industry since the coating of silica may contribute to the fibre-to-fibre bonding, thus improving paper strength

Paper making behaviour of a modified filler obtained by layer-by-layer technique

One way of increasing the filler content in paper without sacrificing the mechanical properties is based on the modification of the filler surface with compounds that promote a better bonding with the cellulosic fibres. In this context, sodium alginate was deposited at the surface of precipitated calcium carbonate (PCC) as a first layer and alternated successive layers of Cationic poly(diallyldimethylammonium) chloride – polyDadmac and alginate were applied using a layer-by-layer (LbL) procedure. The analysis of the synthesized new materials showed that there is a deposition of the negative and positive polyelectrolites at the surface of PCC. In fact by XPS it was confirmed that small amounts of the polyelectrolytes are present at the surface of PCC. Papermaking tests were carried out using the new composites. An improvement of the handsheets strength properties was observed when comparing to handsheets produced with the unmodified PCC