Plasma-Induced Fibrillation and Surface Functionalization of Cellulose Microfibrils

The classical production of microfibrillar cellulose involves intensive mechanical processing and discontinuous chemical treatment in solvent-based media in order to introduce additional chemical surface modification. By selecting appropriate conditions of a pulsed plasma reactor, a solvent-free and low-energy input process can be applied with the introduction of microcrystalline cellulose (MCC) and maleic anhydride (MA) powders. The plasma processing results in the progressive fibrillation of the cellulose powder into its elementary fibril structure and in-situ modification of the produced fibrils with more hydrophobic groups that provide good stability against re-agglomeration of the fibrils. The selection of a critical ratio MA/MCC = 2:1 allows separating the single cellulose microfibrils with changeable morphologies depending on the plasma treatment time. Moreover, the density of the hydrophobic surface groups can be changed through a selection of different plasma duty cycle times, while the influence of plasma power and pulse frequency is inferior. The variations in treatment time can be followed along the plasma reactor, as the microfibrils gain smaller diameter and become somewhat longer with increasing time. This can be related to the activation of the hierarchical cellulose structure and progressive diffusion of the MA within the cellulose structure, causing progressive weakening of the hydroxyl bonding. In parallel, the creation of more reactive species with time allows creating active surface sites that allow for interaction between the different fibrils into more complex morphologies. The in-situ surface modification has been demonstrated by XPS and FTIR analysis, indicating the successful esterification between the MA and hydroxyl groups at the cellulose surface. In particular, the crystallinity of the cellulose has been augmented after plasma modification. Furthermore, AFM evaluation of the fibrils shows surface structures with irregular surface roughness patterns that contribute to better interaction of the microfibrils after incorporation in an eventual polymer matrix. In conclusion, the combination of physical and chemical processing of cellulose microfibrils provides a more sustainable approach for the fabrication of advanced nanotechnological materials.

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Surface Modification of Polyamides by Gaseous Plasma—Review and Scientific Challenges

Polymers ◽

10.3390/polym12123020 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3020

Author(s):

Gregor Primc

Keyword(s):

Surface Modification ◽

Oxygen Concentration ◽

Treatment Time ◽

Plasma Reactor ◽

Prolonged Treatment ◽

Water Contact ◽

Static Water ◽

Nitrogen Concentrations ◽

Polar Functional Groups ◽

Almost All

A review of the most significant scientific achievements in the field of surface modification of polyamides by non-equilibrium plasma treatments is presented. Most authors employed atmospheric pressure discharges and reported improved wettability. The super-hydrophilic surface finish was only achieved using a low-pressure plasma reactor and prolonged treatment time, enabling both the nanostructuring and functionalization with polar functional groups. The average increase of the oxygen concentration as probed by XPS was about 10 at%, while the changes in nitrogen concentrations were marginal in almost all cases. The final static water contact angle decreased with the increasing treatment time, and the oxygen concentration decreased with the increasing discharge power. The need for plasma characterization for the interpretation of experimental results is stressed.

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Surface Modification of Fumed Silica by Plasma Polymerization of Acetylene for PP/POE Blends Dielectric Nanocomposites

Polymers ◽

10.3390/polym11121957 ◽

2019 ◽

Vol 11 (12) ◽

pp. 1957 ◽

Cited By ~ 3

Author(s):

Xiaozhen He ◽

Ilkka Rytöluoto ◽

Rafal Anyszka ◽

Amirhossein Mahtabani ◽

Eetta Saarimäki ◽

...

Keyword(s):

Surface Modification ◽

Photoelectron Spectroscopy ◽

Plasma Polymerization ◽

Silica Surface ◽

Plasma Reactor ◽

Charge Trapping ◽

Plasma Modification ◽

Modified Silica ◽

Depolarization Current ◽

X Ray

Novel nanocomposites for dielectric applications-based polypropylene/poly(ethylene-co-octene) (PP/POE) blends filled with nano silica are developed in the framework of the European ‘GRIDABLE’ project. A tailor-made low-pressure-plasma reactor was applied in this study for an organic surface modification of silica. Acetylene gas was used as the monomer for plasma polymerization in order to deposit a hydrocarbon layer onto the silica surface. The aim of this modification is to increase the compatibility between silica and the PP/POE blends matrix in order to improve the dispersion of the filler in the polymer matrix and to suppress the space charge accumulation by altering the charge trapping properties of these silica/PP/POE blends composites. The conditions for the deposition of the acetylene plasma-polymer onto the silica surface were optimized by analyzing the modification in terms of weight loss by thermogravimetry (TGA). X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray fluorescence spectroscopy (EDX) measurements confirmed the presence of hydrocarbon compounds on the silica surface after plasma modification. The acetylene plasma modified silica with the highest deposition level was selected to be incorporated into the PP/POE blends matrix. X-ray diffraction (XRD) showed that there is no new crystal phase formation in the PP/POE blends nanocomposites after addition of the acetylene plasma modified silica. Differential scanning calorimetry results (DSC) show two melting peaks and two crystallization peaks of the PP/POE blends nanocomposites corresponding to the PP and POE domains. The improved dispersion of the silica after acetylene plasma modification in the PP/POE blends matrix was shown by means of SEM–EDX mapping. Thermally stimulated depolarization current (TSDC) measurements confirm that addition of the acetylene plasma modified silica affects the charge trapping density and decreases the amount of injected charges into PP/POE blends nanocomposites. This work shows that acetylene plasma modification of the silica surface is a promising route to tune charge trapping properties of PP/POE blend-based nanocomposites.

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Gray optimization of process parameters of surface modification of coconut sheath reinforced polymer composites

Journal of Polymer Engineering ◽

10.1515/polyeng-2012-0151 ◽

2013 ◽

Vol 33 (7) ◽

pp. 665-672 ◽

Cited By ~ 2

Author(s):

Irullappasamy Siva ◽

Jebas Thangaih Winowlin Jappes ◽

Pandian Pitchipoo ◽

Sandro Campos Amico ◽

Erumaipatty Rajagounder Nagarajan ◽

...

Keyword(s):

Surface Modification ◽

Natural Fiber ◽

Treatment Time ◽

Natural Fibers ◽

Technical Information ◽

Interfacial Strength ◽

Bath Temperature ◽

Reinforced Polymer ◽

Optimization Of Process Parameters ◽

Selection Of

Abstract Surface modification of natural fiber may greatly enhance the mechanical interlocking between fiber and matrix. Although there are many reports on surface modification of natural fibers, little technical information is available to enable the selection of optimized surface modification conditions. In this work, treatment parameters, such as bath temperature, agent concentration, and treatment time, are optimized to achieve higher interfacial adhesion. The effect of these parameters on flexural and impact strength is investigated by applying gray relational techniques. Experimental results show that NaOH concentration and treatment time are significant variables which improve interfacial strength, while NaOH bath temperature appears less important.

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State-of-the-Art Recovery of Fermentative Organic Acids by Ionic Liquids: An Overview

Hungarian Journal of Industry and Chemistry ◽

10.1515/hjic-2017-0019 ◽

2017 ◽

Vol 45 (2) ◽

pp. 41-44

Author(s):

Konstantza Tonova

Keyword(s):

Ionic Liquids ◽

Organic Acids ◽

Experimental Studies ◽

Hydroxyl Groups ◽

Diverse Range ◽

Chemical Structures ◽

Liquid Liquid Extraction ◽

Method Of Extraction ◽

Selection Of

Abstract The main achievements of liquid–liquid extraction (LLE) of fermentative organic acids from their aqueous sources using a diverse range of ionic liquids are summarized since the first study appeared in 2004. The literature survey is organized in consideration of the distinct chemical structures of the organic acids. The acids discussed include mono– or dicarboxylic ones (butyric, L-malic and succinic acids), acids bearing both carboxyl and hydroxyl groups (L-lactic, citric and mevalonic acids), and volatile organic acids (mainly acetic acid). Information is given about ionic liquids applied in recovery, and the resultant extraction efficiencies and partition coefficients. As the topic is novel and experimental studies scarce, the selection of the ionic liquids that were tested still seems random. This may well change in the future, especially after improving the ecological and toxicological characteristics of the ionic liquids in order to bring about an “in situ” method of extraction without harming the microbial producers of the organic acids.

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Study on the Chemical Modification Process of Jute Fiber

TAPPI Journal ◽

10.32964/tj9.2.23 ◽

2010 ◽

Vol 9 (2) ◽

pp. 23-29 ◽

Cited By ~ 1

Author(s):

Wei-ming Wang ◽

Zai-sheng Cai ◽

Jian-yong Yu

Keyword(s):

Sodium Hydroxide ◽

Sodium Silicate ◽

Treatment Time ◽

Jute Fiber ◽

Process Conditions ◽

Silicate Concentration ◽

Sodium Hydroxide Concentration ◽

Liquor Ratio ◽

Degumming Process ◽

Selection Of

Degumming of pre-chlorite treated jute fiber was studied in this paper. The effects of sodium hydroxide concentration, treatment time, temperature, sodium silicate concentration, fiber-to-liquor ratio, penetrating agent TF-107B concentration, and degumming agent TF-125A concentration were the process conditions examined. With respect to gum decomposition, fineness and mechanical properties, sodium hydroxide concentration, sodium silicate concentration, and treatment time were found to be the most important parameters. An orthogonal L9(34) experiment designed to optimize the conditions for degumming resulted in the selection of the following procedure: sodium hydroxide of 12g/L, sodium silicate of 3g/L, TF-107B of 2g/L, TF-125A of 2g/L, treatment time of 105 min, temperature of 100°C and fiber to liquor ratio of 1:20. The effect of the above degumming process on the removal of impurities was also examined and the results showed that degumming was an effective method for removing impurities, especially hemicellulose.

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Properties and Applications of Modified Bacterial Cellulose-Based Materials

Current Nanoscience ◽

10.2174/1573413716999201106145528 ◽

2020 ◽

Vol 16 ◽

Author(s):

Munair Badshah ◽

Hanif Ullah ◽

Fazli Wahid ◽

Taous Khan

Keyword(s):

Surface Modification ◽

Bacterial Cellulose ◽

Degree Of Polymerization ◽

Biomedical Science ◽

Hydroxyl Groups ◽

Market Demand ◽

Ideal Candidate ◽

Fibrous Network ◽

Potential Applications ◽

Surface Modification Techniques

Background: Bacterial cellulose (BC) is purest form of cellulose as it is free from pactin, lignin, hemicellulose and other active constituents associated with cellulose derived from plant sources. High biocompatibility and easy molding into desired shape make BC an ideal candidate for applications in biomedical field such as tissue engineering, wound healing and bone regeneration. In addition to this, BC has been widely studied for applications in the delivery of proteins and drugs in various forms via different routes. However, BC lacks therapeutic properties and resistance to free movement of small molecules i.e., gases and solvents. Therefore, modification of BC is required to meet the research ad market demand. Methods: We have searched the updated data relevant to as-synthesized and modified BC, properties and applications in various fields using Web of science, Science direct, Google and PubMed. Results: As-synthesized BC possesses properties such as high crystallinity, well organized fibrous network, higher degree of polymerization, and ability of being produced in swollen form. The large surface area with abundance of free accessible hydroxyl groups makes BC an ideal candidate for carrying out surface functionalization to enhance its features. The various reported surface modification techniques including, but not limited to, are amination, methylation and acetylation. Conclusion: In this review, we have highlighted various approaches made for BC surface modification. We have also reported enhancement in the properties of modified BC and potential applications in different fields ranging from biomedical science to drug delivery and paper-making to various electronic devices.

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F/OH ratio in a rare fluorine-poor blue topaz from Padre Paraíso (Minas Gerais, Brazil) to unravel topaz’s ambient of formation

Scientific Reports ◽

10.1038/s41598-021-82045-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

N. Precisvalle ◽

A. Martucci ◽

L. Gigli ◽

J. R. Plaisier ◽

T. C. Hansen ◽

...

Keyword(s):

Supercritical Fluids ◽

Fluorine Content ◽

Minas Gerais ◽

Hydroxyl Groups ◽

Exchange Reactions ◽

Silicate System ◽

Mullite Phase ◽

Anomalous Water

AbstractTopaz [Al2SiO4(F,OH)2] is one of the main fluorine-bearing silicates occurring in environments where variably acidic (F)/aqueous (OH) fluids saturate the silicate system. In this work we fully characterized blue topaz from Padre Paraíso (Minas Gerais, Brazil) by means of in situ synchrotron X-Ray and neutron powder diffraction measurements (temperature range 298–1273 K) combined with EDS microanalyses. Understanding the role of OH/F substitution in topaz is important in order to determine the hydrophilicity and the exchange reactions of fluorine by hydroxyl groups, and ultimately to characterize the environmental redox conditions (H2O/F) required for mineral formation. The fluorine content estimated from neutron diffraction data is ~ 1.03 a.f.u (10.34 wt%), in agreement with the chemical data (on average 10.0 wt%). The XOH [OH/(OH + F)] (0.484) is close to the maximum XOH value (0.5), and represents the OH- richest topaz composition so far analysed in the Minas Gerais district. Topaz crystallinity and fluorine content sharply decrease at 1170 K, while mullite phase starts growing. On the basis of this behaviour, we suggest that this temperature may represent the potential initial topaz’s crystallization temperature from supercritical fluids in a pegmatite system. The log(fH2O/fHF)fluid (1.27 (0.06)) is coherent with the fluorine activity calculated for hydrothermal fluids (pegmatitic stage) in equilibrium with the forming mineral (log(fH2O/fHF)fluid = 1.2–6.5) and clearly different from pure magmatic (granitic) residual melts [log(fH2O/fHF)fluid < 1]. The modelled H2O saturated fluids with the F content not exceeding 1 wt% may represent an anomalous water-dominant / fluorine-poor pegmatite lens of the Padre Paraíso Pegmatite Field.

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Morphology Controlled Synthesis of γ-Al2O3 Nano-Crystallites in Al@Al2O3 Core–Shell Micro-Architectures by Interfacial Hydrothermal Reactions of Al Metal Substrates

Nanomaterials ◽

10.3390/nano11020310 ◽

2021 ◽

Vol 11 (2) ◽

pp. 310

Author(s):

Dohyeon Han ◽

Doohwan Lee

Keyword(s):

Electrostatic Interactions ◽

Heterogeneous Catalysts ◽

Metal Substrate ◽

Inorganic Anions ◽

Core Shell ◽

Hydroxyl Groups ◽

Hydrothermal Reactions ◽

Fine Control ◽

Reaction Processes

Fine control of morphology and exposed crystal facets of porous γ-Al2O3 is of significant importance in many application areas such as functional nanomaterials and heterogeneous catalysts. Herein, a morphology controlled in situ synthesis of Al@Al2O3 core–shell architecture consisting of an Al metal core and a porous γ-Al2O3 shell is explored based on interfacial hydrothermal reactions of an Al metal substrate in aqueous solutions of inorganic anions. It was found that the morphology and structure of boehmite (γ-AlOOH) nano-crystallites grown at the Al-metal/solution interface exhibit significant dependence on temperature, type of inorganic anions (Cl−, NO3−, and SO42−), and acid–base environment of the synthesis solution. Different extents of the electrostatic interactions between the protonated hydroxyl groups on (010) and (001) facets of γ-AlOOH and the inorganic anions (Cl−, NO3−, SO42−) appear to result in the preferential growth of γ-AlOOH toward specific crystallographic directions due to the selective capping of the facets by adsorption of the anions. It is hypothesized that the unique Al@Al2O3 core–shell architecture with controlled morphology and exposed crystal-facets of the γ-Al2O3 shell can provide significant intrinsic catalytic properties with enhanced heat and mass transport to heterogeneous catalysts for applications in many thermochemical reaction processes. The direct fabrication of γ-Al2O3 nano-crystallites from Al metal substrate with in-situ modulation of their morphologies and structures into 1D, 2D, and 3D nano-architectures explored in this work is unique and can offer significant opportunities over the conventional methods.

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Effect of Na- and Organo-Modified Montmorillonite/Essential Oil Nanohybrids on the Kinetics of the In Situ Radical Polymerization of Styrene

Nanomaterials ◽

10.3390/nano11020474 ◽

2021 ◽

Vol 11 (2) ◽

pp. 474

Author(s):

Ioannis S. Tsagkalias ◽

Alexandra Loukidi ◽

Stella Chatzimichailidou ◽

Constantinos E. Salmas ◽

Aris E. Giannakas ◽

...

Keyword(s):

Essential Oil ◽

Radical Polymerization ◽

Food Packaging ◽

In Situ Polymerization ◽

Average Molecular Weight ◽

Monomer Conversion ◽

Hydroxyl Groups ◽

Modified Montmorillonite ◽

Kinetics Of

The great concern about the use of hazardous additives in food packaging materials has shown the way to new bio-based materials, such as nanoclays incorporating bioactive essential oils (EO). One of the still unresolved issues is the proper incorporation of these materials into a polymeric matrix. The in situ polymerization seems to be a promising technique, not requiring high temperatures or toxic solvents. Therefore, in this study, the bulk radical polymerization of styrene was investigated in the presence of sodium montmorillonite (NaMMT) and organo-modified montmorillonite (orgMMT) including thyme (TO), oregano (OO), and basil (BO) essential oil. It was found that the hydroxyl groups present in the main ingredients of TO and OO may participate in side retardation reactions leading to lower polymerization rates (measured gravimetrically by the variation of monomer conversion with time) accompanied by higher polymer average molecular weight (measured via GPC). The use of BO did not seem to affect significantly the polymerization kinetics and polymer MWD. These results were verified from independent experiments using model compounds, thymol, carvacrol and estragol instead of the clays. Partially intercalated structures were revealed from XRD scans. The glass transition temperature (from DSC) and the thermal stability (from TGA) of the nanocomposites formed were slightly increased from 95 to 98 °C and from 435 to 445 °C, respectively. Finally, better dispersion was observed when orgMMT was added instead of NaMMT.

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