Effect of Mannanase and Lipase on the properties of colloidal wood extractives and their interaction with mechanical pulp fines

The effects of enzymatic treatments of dissolved and colloidalsubstances (DCS) released from thermomechanical pulp (TMP) have beeninvestigated. A model dispersion of DCS was made by leaching several portionsofTMP in distilled water and separating the fibrous material. Some samples wereenriched in colloidal particles by removing dissolved substances usingultra-filtration. The DCS, which had been subjected to different enzymatictreatments, were added in a fixed quantity to TMP fines that had been madecationic, and were subsequently used to form handsheets. All DCS additionsincreased the content of lipophilic extractives in the sheets. Lipase gave acomplete hydrolysation of triglycerides into free fatty acids. The untreatedDCSgave no significant decrease in tensile strength, because of the relativelysmall addition. A treatment of the DCS with Lipase gave a higher extractivescontent and a tensile strength on the same level as the reference. A Mannanasetreatment gave a decrease in strength compared with the reference at the sameamount of extractives in the sheet. A combined treatment with Mannanase andLipase gave a more pronounced decrease in tensile strength. Two possiblereasonsfor the differences in strength at a given amount of extractives weresuggested:(i) the destabilisation of the colloidal wood extractivesdue to the Mannanase could affect the distribution of the colloid in the sheet,making it more detrimental to sheet strength compared with the stable colloid.This would account for the observation that Lipase did not affect sheetstrengthas such, but the combination with Mannanase gave the lowest tensilestrength; (ii) the decomposition of galactoglucomannans in aqueoussolution would diminish their positive effect on tensile strength and/or affectthe adsorption of the colloid. A reflectometry technique was used to quantifythe adsorption of the differently treated DCS onto a model surface of thecationic fines. Colloidal wood extractives were identified on the surfacesafteradsorption using staining and light microscopy. No variations in adsorbedamounts were found that could explain the differences in sheet strength, whichindirectly suggests that the distribution of the colloid over the surface wasaffecting the ability of a strong bonded joint to be formed between two suchsurfaces.     

The effect of chemical modification on the strength of wood and bonded wood joints

The effect of propionic, crotonic or methacrylic anhydride (MA) modification on the lab joint strength of monomer bonded veneer strips was investigated. Lap joints were formed by hot pressing veneers of modified wood with monomer in the presence of free radical initiator and bond strength was determined on an Automatic Bonding Evaluation System tensile tester. Test results indicated that chemical treatment improved bond quality between hydrophilic wood and hydrophobic monomer. Extremely strong bonds (wet and dry conditions) formed in the case of MA modified veneer strips. In addition, the effect of chemical modification on the mechanical properties of strips was also investigated. Chemical modification had a detrimental effect on the mechanical properties.     

The influence of ionic liquid's nature on free radical polymerization of vinyl monomers and ionic conductivity of the obtained polymeric materials

Various 1,3‐dialkylimidazolium and tetraalkylphosphonium ionic liquids (ILs), including novel ones, have been studied as reaction media for free radical polymerization of methyl methacrylate (MMA), acrylonitrile (AN) and 1‐vinyl‐3‐ethylimidazolium salts (ViEtIm⁺)Y^?. The influence of IL's nature upon the polymer formulation was investigated. The use of different ionic liquids allows not only to obtain the polymers with high molecular weight (PMMA, up to 5,770,000 g/mol; PAN, up to 735,000 g/mol and poly[(ViEtIm⁺)Y^?], up to 1,130,000 g/mol) in high yields, but also to control the polymerization rate and molecular mass. The physicochemical characteristics, including mechanical properties, thermal stability and heat‐resistance of the obtained polymers were studied in order to compare with those of polymers prepared in a traditional media. It was found that elongation, tensile modulus and strength of PAN, which was synthesized in ionic liquid, are reliatively higher. The influence of IL's nature upon their ionic conductivity and the formation of conductive polymers from molten‐salt‐type vinyl monomers was investigated. Molecular design of the polymers simultaneously with the influence of IL's nature in order to achieve higher ionic conductivity is discussed. Flexible, transparent polymer films, obtained in different ways, show relatively high ionic conductivity (of about 10^?5 S cm^?1 at 20°C). Copyright © 2006 John Wiley & Sons, Ltd.     

Multi-step sol-gel process and its effect on the morphology of polyethylene oxide (PEO)/SiO2 anion-exchange hybrid materials

Polyethylene oxide (PEO)/SiO₂ anion-exchange hybrid materials were prepared through the sol-gel process of alkoxysilane functionalized PEO-1000 (PEO-[Si(OCH₃)₃]₂) and N-[3-(trimethoxysilyl)propyl] ethylene diamine (A-1120). The influence of the multi-step sol-gel processing procedure, i.e. the pre-hydrolysis of either of the two precursors on the homogeneity of the hybrid materials was investigated. Results showed that the sol-gel reaction of A-1120 and PEO-[Si(OCH₃)₃]₂ from the same time would result in hybrid materials with the highest homogeneity, and pre-hydrolysis of A-1120 or PEO-[Si(OCH₃)₃]₂ could only decrease the materials’ compatibility.     

Synthesis and characterization of novel phenolic resins containing aryl‐boron backbone and their utilization in polymeric composites with improved thermal and mechanical properties

In the present study, a novel aryl‐boron‐containing phenolic resin named as PBPR has been synthesized from phenol and formaldehyde in the presence of phenylboronic acid. The chemical structure of the PBPR was confirmed by Fourier transform infrared, nuclear magnetic resonance and X‐ray photoelectron spectroscopy. The molecular weight, viscosity and curing behavior were examined to demonstrate that PBPRs have better processability than common boric acid‐modified phenolic resin. The thermal stability and fracture toughness of the cured PBPRs were greatly enhanced, where the char yield at 1000°C (nitrogen atmosphere) and the glass transition temperature reached 70.0% and 218°C, respectively. The excellent mechanical and ablative properties of the PBPR composites may have benefited from the good interfacial adhesion between the resin matrix and the reinforced fiber. The flexural strength and the linear ablative rate are 436.8 ± 5.2 MPa and 0.010 mm/sec, respectively. This study opens a new window for the preparation of high‐performance ablative composites by designing a resin matrix containing an aryl‐boron backbone. Copyright © 2013 John Wiley & Sons, Ltd.     

The effect of Trichoderma reesei cellulases and hemicellulases on the paper technical properties of never-dried bleached kraft pulp

Four purified cellulases, a xylanase and mannanase from Trichoderma reesei were used to treat never-dried bleached pine kraft pulp prior to refining, and the effects on pulp properties were evaluated. The enzymatic treatments hydrolysed up to 0.8% of pulp dry weight. The results demonstrated that the individual cellulases have profoundly different modes of action in modifying pulp carbohydrates. This is especially clear when comparing their effects at the same level of hydrolysis. Pretreatment with cellobiohydrolases I (CBH I) and II (CBH II) had virtually no effect on the development of pulp properties during refining, except for a slight decrease in strength properties. On the contrary, endoglucanase I (EG I) and endoglucanase II (EG II) improved the beatability of the pulp as measured by Schopper--Riegler value, sheet density and Gurley air resistance. Of the endoglucanases, EG II was most effective in improving the beating response. The combinations of CBH I with EG I and EG II had similar effects on the pulp properties as the endoglucanases alone, although the amount of hydrolysed cellulose was increased. Pretreatments with xylanase or mannanase did not appear to modify the pulp properties. The same enzyme treatments which improved the beatability, however, slightly impaired the pulp strength, especially tear index at the enzyme dosages used. When compared at a given level of cellulose hydrolysis, the negative effect of EG II on strength properties was more pronounced compared with EG I. Thus, the exploitation of cellulases for fibre treatments requires careful optimization of both enzyme composition and dosage. Since the endoglucanases had no positive effect on the development of tensile strength, it is suggested that the explanation for the increased beating response is increased fibre breakage and formation of fines, rather than improved flexibilization. This revised version was published online in August 2006 with corrections to the Cover Date.     

The effect of radiation on the physical and chemical properties of polyethylene containing an antioxidant and/or other additives

This paper describes the effect of an antioxidant, a monomer and fillers (silica or carbon black), alone or in certain combinations with each other, on the mechanical and chemical response of a low density polyethylene to exposure to ionizing radiation. If chain scission is a significant factor in the radiolysis of a polymer, then the relation between sol fraction and Young's modulus or ultimate elongation (both at 160°C) should change depending on whether an additive inhibits or enhances crosslinking. Such additives do not significantly or consistently alter the relation between these properties in a low density polyethylene, indicating that chain scission is not a significant feature of the radiolysis of this polymer.     

Experimental investigation of the effect of initial fuel particle shape, size and bed temperature on devolatilization of single wood particle in a hot fluidized bed

Considerable amount of investigation on the subject of devolatilization of wood is found in the open literature. However, a systematic study of the effect of initial particle size and shape, and bed temperature on devolatilization time and char yield of wood in a hot fluidized bed is still missing. This paper attempts to fill this gap through a systematic experimental investigation to determine the devolatilization time and char yield of a typical woody biomass, “Casuarina equisetifolia” particles of different initial sizes and shapes at various fluidized bed temperatures. Experiments are conducted using 10, 15, 20, and 25 mm Casuarina wood particles of three shapes, namely, cube, cylinder, and sphere at bed temperatures of 1023, 1123, and 1223 K.It is found that the initial wood particle size has the strongest influence on devolatilization time followed by the shape of initial wood particle and the bed temperature. Correlation for devolatilization time (τ_d) as a function of initial wood particle size (d_eq), sphericity (?), and bed temperature (T_b), is developed using 573 experimental data points exhibiting a correlation coefficient of 0.96 and predictions falling well within a deviation band of ±20%. The predictions of the present correlation are compared with the predictions of the existing correlations in literature for conditions also out of the present study and the deviation is found to be ±30%.Char yield, defined as the ratio of the residual mass at the end of devolatilization process to the initial mass of the wood particle is found to be in the range of 9-14% for all sizes, shapes, and bed temperatures. Char yield does not depict any definite trend with the variation of initial particle size, shape and bed temperature.     

Influence of surface modified graphene oxide on the mechanical performance and curing kinetics of epoxy resin

In this study, the hyperbranched polyester were successfully grafted onto graphene oxide (GO). The mechanical performance and curing kinetics of epoxy resin (EP), EP/ graphene oxide (EP/GO), and EP/ hyperbranched polyester grafted GO (EP/GO‐B) were investigated by means of mechanical tests and differential scanning calorimetry (DSC). Results revealed that the presence of GO lowered the cure temperature and accelerated the curing of EP, and the addition of GO‐B exhibited a stronger effect in accelerating the cure of EP compared with GO. Activation energies were calculated using Kissinger approach, and Ozawa approach, respectively. Results revealed lowered activation energy after the addition of GO or GO‐B at low degrees of cure, indicating that GO had a large effect on the curing reaction. The presence of GO facilitated the curing reaction, especially the initial epoxy‐amine reaction. Moreover, GO‐B exhibited better performance. Related mechanism was proposed.     

Synthesis of novel thermosetting imide compounds having phenylethynyl carbonyl groups at both terminal ends and production of new network polymers based on the imide compounds

A novel thermosetting imide compound having a respective phenylethynyl carbonyl group at both terminal ends was newly synthesized from an acid anhydride having a phenylethynyl carbonyl group and various diamine compounds. The thermosetting behavior of the obtained novel thermosetting imide compound having phenylethynyl carbonyl groups was analyzed through differential scanning calorimetry measurements and infrared spectroscopic analysis. As a result, it became clear that a curing reaction of phenylethynyl carbonyl groups proceeds at approximately 200°C and that the curing reaction thereof proceeds at a temperature that is lower by 150°C or more compared with that of phenylethynyl groups. Examination of the polymerization reaction of the imide compounds having phenylethynyl carbonyl groups using model compounds revealed that a reaction that imparted an alkene C=C and polycyclic aromatic structure progressed. Moreover, a network polymer obtained from a thermosetting imide compound having respective phenylethynyl carbonyl groups at both terminal ends exhibited extremely superior heat resistance and thermal decomposition resistance. These superior thermal properties are thought to be due to the strong molecular interaction (molecular packing) that results from the polycyclic aromatic structures and alkenes produced through polymerization of the phenylethynyl carbonyl groups and to the suppression of the movement of the molecular chains.     

Morphology and properties of globular polymeric materials in the solid state: A composite material of DNA with a cationic surfactant

The aim of the present study was to control entanglements in order to regulate the properties of polymeric solids. Initially, fabrication of polymeric solids with few entanglements was attempted. Films of the DNA–cationic surfactant, cetyltrimethylammonium bromide (CTAB) (DNA–CTA), were cast from ethanol solution at room temperature. Morphological examination of DNA–CTA complex films using atomic force microscopy (AFM) revealed that these films were constructed by particle‐like substances. Geometrical analysis of AFM images showed that the particle‐like substances were the aggregates of several DNA–CTA globules. Mechanical characterization suggested that there were fewer entanglements than with normal plastic films. Small angle X‐ray scattering experiments during annealing indicated that molecular motions were highly excited in the surface region of each particle. In conclusion, a globular polymeric film with fewer entanglements was fabricated. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 730–738     

Quantification of the surface morphologies of lactose carriers and their effect on the in vitro deposition of salbutamol sulphate

Application of the scanning probe microscopy technique for quantitative measurement of the surface roughness of lactose carriers was evaluated. The roughness values of four different lactose carriers were related to the in vitro deposition results of the drug, salbutamol sulphate. The rugosity values of the lactose carriers were represented by Ra values which were in the order of DCL-40>DCL-11>lactose 325M>lactose 200 M. In vitro deposition results using a twin impinger showed that rougher carrier surfaces generally allowed more drug particles to be emitted from the capsules and inhaler but the availability of the drug to stage 2 was reduced, as detachment of drug particles from the carrier surfaces was more hindered. There was an optimum Ra value for greater delivery of the drug particles to stage 2 of the twin impinger. A balance between adherence and detachment of the drug from the carrier surface was needed in order to optimize the delivery of a drug to the desired target sites using a dry powder inhaler.     

Synthesis of polymethacrylamides having a sugar moiety with an aliphatic hydrocarbon spacer and their application to control adhesion of hepatocytes cancer cells on the materials

Polymers having a sugar moiety in the side group have been utilized as artificial matrices for cell adhesion in tissue engineering. In this study, methacrylamide ‐ based polymers having lactose and maltose derivative structures in the side group with various aliphatic hydrocarbon spacers were synthesized, and their cell adhesion properties were examined. Methacrylamide monomers were prepared by two step amidation of a spacer diamine, first with a sugar lactone and then with a methacrylic anhydride. These monomers were radically polymerized in aqueous media using 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) as radical initiator to give the corresponding polymethacrylamide. Specific interaction between these polymers and animal cell was investigated by adhesion of proliferated human liver cancer cell (WRL) to the polymethacrylamides. WRL interacted with polymers having a lactose structure with a hexamethylene or 1,4‐cyclohexylene spacer by a specific manner and was promoted typical spheroid formation, while it did not interacted with polymers having a maltose structure. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4003–4010     

Formation of coordination polymeric structures on the basis of 4,4"-dipyridylethylene and Ag+ in solutions

The formation of coordination polymeric chain structures in which silver ions alternate with dipyridylethylene (DPyEt) ligands was studied. In a homogeneous ethanol solution, complex formation of DPyEt with silver cations takes place. The outcome of this reaction depends on the ligand/cation molar ratio, the initial ligand concentration, and the counter-ion type. Conditions were identified under which the coordination polymer is formed as a microdispersed solid precipitating from the solution. The precipitates formed in the DPyEt—AgNO₃ and DPyEt—AgClO₄ systems were investigated by various experimental techniques. The counter-ion was found to be incorporated in the polymer and to influence the structure of the precipitate particles.     

Synergistic effect of bismuth oxide and mono‐component intumescent flame retardant on the flammability and smoke suppression properties of epoxy resins

A novel mono‐component intumescent flame retardant named pentaerythritol phosphate melamine salt (PPMS)‐hybrid bismuth oxide (PPMS‐Bi₂O₃) was synthesized and carefully characterized by FTIR, ¹H NMR, ³¹P NMR, SEM‐EDS, and TG analyses. Then, PPMS‐Bi₂O₃ was utilized as flame retardant for epoxy resins (EPs), and the thermal stability, flame retardancy, and smoke suppression properties of EP composites were investigated. TG results show that PPMS‐Bi₂O₃ is more conducive to enhance the thermal stability and char forming ability of EP composites compared with the same addition of PPMS or the mixture of PPMS and Bi₂O₃, and this positive effect is enhanced with the increasing Bi₂O₃ content. Cone calorimeter test reveals that the PPMS‐Bi₂O₃ can effectively reduce the heat release and smoke production in comparison with PPMS or the mixture of PPMS and Bi₂O₃ due to the formation of a more compact and intumescent char against fire, as judged by digital photographs and SEM images. EDS analysis indicates that the combination PPMS and Bi₂O₃ by hydrogen bonds promotes to generate more phosphorus‐rich and aromatization structures in the condensed phase that enhance the barrier effect and anti‐oxidation ability of the char, thus imparting higher flame retardant and smoke suppression efficiencies to EP composites.     

Influence of hydrophilic and hydrophobic low-molecular-weight additives on the thermoresponsiveness of star-shaped poly-2-isopropyl-2-oxazoline in solution

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Size effect in the titanium/diamond‐like carbon bilayer films: effect of relative thickness on their structure and mechanical properties

Titanium/diamond‐like carbon (Ti/DLC) bilayer films with different relative thickness were fabricated by direct‐current and pulsed cathode arc plasma method. Microstructure, morphological characteristics, and mechanical properties of the films were investigated in dependence of the thickness of Ti and DLC layers by Raman spectroscopy, atomic force microscopy, Knoop sclerometer, and surface profilometer. Raman spectra of Ti/DLC bilayers show the microstructure evolution (the size and ordering degree of sp²‐hybridized carbon clusters) with varying the thicknesses of Ti interlayer and DLC layer. Nano‐scaled Ti interlayer of 12–20 nm thickness presents the largest size effect. The catalytic effect of the sublayer is most pronounced in the carbon layer of less than 106 nm. In these thickness ranges, the bilayer films possessed the highest micro‐hardness and reactivity between atoms at interface. Internal stress in the bilayer monotonically decreases, with the thickness of Ti interlayer increasing to 30 nm and then becomes stable with the thickness. These results are associated with the occurrence of atomic diffusion process at Ti/C interface, and they are of cardinal significance to optimize the structure and mechanical properties of carbon‐based multilayer films. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of preparation of titania sol on the structure and properties of acrylic resin/titania hybrid materials

Acrylic resin/titania organic–inorganic hybrid materials were prepared by mixing titania sol produced by the sol–gel process with synthesized thermoplastic acrylic resins. The effects of the amounts of water and acid on hydrolysis and condensation of the sol–gel precursor (titanium n‐butoxide) were characterized by nuclear magnetic resonance, and their corresponding influences on the structure and properties of the hybrid films were investigated by small‐angle X‐ray scattering (SAXS), atomic force microscopy, dynamical mechanical analysis, an Instron testing machine, and ultraviolet–visible spectroscopy. SAXS indicated an open structure and nanoscale size for the titania phase of the hybrids. Higher titania content and a greater amount of water or acid in the sol–gel process resulted in titania domains that were larger size and had a more compact structure. The mechanical and UV‐shielding properties of the organic polymer obviously were improved with titania embedded. As the amount of water or acid in the sol–gel process increased, integrative mechanical properties decreased, with the amount of water having a greater impact than the amount of acid on the structure and optical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3682–3694, 2004     

A study on the ink-fiber interfacial interaction in waste printed paper I. The effect of a custom-designed polymeric additive on flotation de-inking of solvent-treated wastepapers

The effect of interaction between solvent and three different kinds of printed wastepaper has been studied. The solubility parameter of the solvent was found to be among the most important in order to obtain an optimum ink-fiber interfacial swelling, necessary for de-inking wastepaper. The degree of ink-fiber interfacial swelling was qualitatively estimated by examining the dispersity of ink particles using an optical microscope. FT-IR analyses were carried out to correlate the degree of dispersion and the ink composition in the printed wastepapers studied. The effect of a selective swelling solvent on the de-inking characteristics of a mixture of old wastepapers was investigated. The solvent treatment of these wastepapers prior to flotation de-inking failed to add any positive effect on the brightness of the de-inked pulp. On the other hand, the incorporation of a custom-designed polymer additive improved the pulp brightness without any solvent treatment. The same additive played a negative role in the presence of a swelling solvent. The function of the polymer additive in the flotation de-inking process is also described.     

Gram-negative bacteria viable in ultrapure water: identification of bacteria isolated from ultrapure water and effect of temperature on their behavior

This study describes the effect of temperature on the behavior of bacteria viable in ultrapure water and the contamination of ultrapure water by bacteria. Three species of bacteria were isolated from ultrapure water (total organic carbon, 60 ppb and 5 ppb; effluent resistivity > 18 MΩ cm at 25°C) and identified by morphological and physiological characteristics. The three isolates were incubated in water for injection and PYG broth to check the growth profile at various temperatures. In PYG broth, temperature influenced the behavior of bacteria directly; however, it did not in water for injection. By checking both viable and non-viable bacterial numbers and endotoxin concentration in pure water, the water was found to be contaminated with non-viable bacteria and newly generated endotoxins besides viable bacteria. A column treatment, a mixed bed of fully regenerated strong acid cation exchange resin (SACER) and strong base anion exchange resin (SBAER), was used to remove bacteria from pure water. Bacteria could not grow on the surfaces of ion exchange resins in the mixed bed. The removal of bacteria was more effective as pure water was circulated through the mixed bed more rapidly.