scholarly journals Topochemistry of heat-treated and N-methylol melamine-modified wood of koto (Pterygota macrocarpa K. Schum.) and limba (Terminalia superba Engl. et. Diels)

Holzforschung ◽  
2013 ◽  
Vol 67 (2) ◽  
pp. 137-146 ◽  
Author(s):  
Karl-Christian Mahnert ◽  
Stergios Adamopoulos ◽  
Gerald Koch ◽  
Holger Militz
Keyword(s):  
Cell Wall ◽  
Wood Species ◽  
Extractive Content ◽  
Chemical Changes ◽  
Heat Treated ◽  
Before And After ◽  
Terminalia Superba ◽  
Uv Microspectrophotometry ◽  
Modified Wood

Abstract To broaden the knowledge about the chemical changes at the cell wall level of differently modified tropical hardwoods, heat-treated and N-methylol melamine (NMM)-treated samples of koto (Pterygota macrocarpa) and limba (Terminalia superba) were prepared. UV microspectrophotometry (UMSP) was applied at 278 and 240 nm as specific wavelengths to analyze chemical alterations of the samples caused by heat and NMM treatment, respectively. The absorbance of koto exceeded that of limba before and after treatment, potentially due to the higher extractive content of the former. Regardless of the wood species, the absorbance of the samples increased with increasing intensity of the NMM treatment. Additionally, the absorbance of lignin within the spectrum of 230–350 nm was altered due to the NMM treatment. The functionality of applying specific wavelengths for the analysis of different modification methods of wood was proven. However, the comparison with literature did not show differences in the absorbance, which could be assigned to the characteristics of tropical hardwoods.

scholarly journals CHEMICAL CHANGES OF CELL WALL COMPONENTS OF HEAT-TREATED WOOD / ALTERAÇÕES QUÍMICAS DOS COMPONENTES DA PAREDE CELULAR DE MADEIRAS TRATADAS TERMICAMENTE

2020 ◽  
Vol 6 (10) ◽  
pp. 79151-79159
Author(s):  
Carolina Rodrigues Barroco ◽  
Danielle Affonso Sampaio ◽  
Renata Nunes Oliveira ◽  
Alexandre Miguel do Nascimento
Keyword(s):  
Cell Wall ◽  
Treated Wood ◽  
Chemical Changes ◽  
Cell Wall Components ◽  
Heat Treated ◽  
Wall Components

scholarly journals Measuring and Analysis Colour of Birch Wood in Digital Picture

2020 ◽  
Vol 28 (3) ◽  
pp. 162-167
Author(s):  
Mária Hrčková ◽  
Pavol Koleda ◽  
Peter Koleda
Keyword(s):  
Wood Species ◽  
Colour Measurement ◽  
Birch Wood ◽  
Colour Space ◽  
Water Steam ◽  
Matlab Program ◽  
Saturated Water ◽  
Heat Treated ◽  
Thermally Modified Wood ◽  
Modified Wood

AbstractThe aim of the research was to verify a new method of measuring the colour of wood. The method was designed to automate wood colour measurement. In the experiments birch wood was used, which was heat treated with saturated water steam. Nikon D3200 camera was used in conjunction with the MATLAB program to implement the method. The assessments were conducted in the colour space of CIE L* a* b*. The measured values confirmed the decrease in lightness from natural to thermally modified wood. The trends of the colour values a* and b* were the same as those reported by the authors who conducted experiments with birch wood. Differences were found in the magnitude of the measured chromatic component a* values. It will be necessary to verify the above facts and determine the reasons for these differences by measuring the colour of other wood species.

Fresh-cut Mango Fruit Slices

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 457b-457 ◽  
Author(s):  
Arunya Limbanyen ◽  
Jeffrey K. Brecht ◽  
Steven A. Sargent ◽  
Jerry A. Bartz
Keyword(s):  
Chilling Injury ◽  
Flesh Color ◽  
Mango Fruit ◽  
Heat Treated ◽  
Before And After ◽  
Yellow Flesh ◽  
Postharvest Life ◽  
Fresh Cut ◽  
Flesh Browning ◽  
Aseptic Conditions

Preparation and handling procedures for fresh-cut mango slices were developed using `Tommy Atkins', `Haden', and `Palmer' mangoes. Fruit with yellow flesh color (no green color remaining) were optimum maturity for fresh-cut in terms of maintenance of acceptable appearance, texture, and taste; riper fruit developed flesh breakdown and more browning. Postharvest life of fresh-cut mango at 5 °C was 8 to 10 d with no evidence of chilling injury and was limited by flesh browning and loss of firmness. Respiration rates ranged from 32 to 40 mg CO2/kg per hr and ethylene production was typically ≤0.1 μl·kg–1·hr–1. The SSC changed little during storage, while pH varied from 3.5 to 4.8 and TA typically declined by 30% to 40%. Peeling to a depth of at least 2 mm and trimming flesh near the stem scar was necessary to minimize browning. Imported fruit that had been heat-treated for insect quarantine showed more severe browning than Florida fruit that had not been heat-treated. Preparation in aseptic conditions and dipping fruit in a 100 ppm NaOCl solution at pH 7 before and after peeling protected against decay during storage but dipping in chlorine after slicing without removal of excess liquid resulted in flesh translucency and breakdown. Dipping in 1% CaCl2 solution had no effect on flesh firmness (Instron) or browning. Storage in an unvented plastic clamshell container, which developed an atmosphere of 2.25% CO2 plus 19% O2, did not improve shelf life, but a MA of 10% CO2 plus 10% O2 was subjectively judged to slow browning and softening and resulted in no off flavor compared to air storage.

scholarly journals Flammability Characteristics of Thermally Modified Meranti Wood Treated with Natural and Synthetic Fire Retardants

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2160
Author(s):  
Milan Gaff ◽  
Hana Čekovská ◽  
Jiří Bouček ◽  
Danica Kačíková ◽  
Ivan Kubovský ◽  
...  
Keyword(s):  
Burning Rate ◽  
Flame Retardants ◽  
Thermal Modification ◽  
Positive Contribution ◽  
Spearman Correlation ◽  
Chemical Changes ◽  
Combustion Properties ◽  
Flammability Characteristics ◽  
Thermally Modified Wood ◽  
Modified Wood

This paper deals with the effect of synthetic and natural flame retardants on flammability characteristics and chemical changes in thermally treated meranti wood (Shorea spp.). The basic chemical composition (extractives, lignin, holocellulose, cellulose, and hemicelluloses) was evaluated to clarify the relationships of temperature modifications (160 °C, 180 °C, and 210 °C) and incineration for 600 s. Weight loss, burning speed, the maximum burning rate, and the time to reach the maximum burning rate were evaluated. Relationships between flammable properties and chemical changes in thermally modified wood were evaluated with the Spearman correlation. The thermal modification did not confirm a positive contribution to the flammability and combustion properties of meranti wood. The effect of the synthetic retardant on all combustion properties was significantly higher compared to that of the natural retardant.

Slip Casting Used as a Forming Technique for Hydroxyapatite Processing

2016 ◽  
Vol 720 ◽  
pp. 219-222 ◽  
Author(s):  
Rubens Lincoln Santana Blazutti Marçal ◽  
Daniel Navarro da Rocha ◽  
Marcelo Henrique Prado da Silva
Keyword(s):  
Slip Casting ◽  
Ceramic Materials ◽  
Processing Route ◽  
Ceramic Suspension ◽  
Polyethylene Glycol 400 ◽  
Density Measurements ◽  
Hydroxyapatite Powder ◽  
Heat Treated ◽  
Thermal Phase ◽  
Before And After

Ceramic materials have particular properties when compared to other classes of materials, exhibiting poor ductility as an example. Slip casting is a widely used ceramic forming technique, and already established in the literature and in the ceramic industry. This study aims to present slip casting as a processing route for producing hydroxyapatite (HA) struts, and show the thermal phase stability. The ceramic suspension was produced and stabilized with hydroxyapatite powder, deionized water and polyethylene glycol 400. The slip was poured into gypsum mold. The green bodies were heat treated at 900 and 1100°C. Hydroxyapatite was the only phase present in all samples, before and after heat treatments. Density measurements showed that the densification was higher for the ceramic bodies sintered at 1100°C, when compared to the ones calcined at 900°C.

Durability of five native Argentine wood species of the genera Prosopis and Acacia decayed by rot fungi and its relationship with extractive content

2010 ◽  
Vol 21 (5) ◽  
pp. 753-760 ◽  
Author(s):  
Carolina L. Pometti ◽  
Sabrina Palanti ◽  
Benedetto Pizzo ◽  
Jean-Paul Charpentier ◽  
Nathalie Boizot ◽  
...  
Keyword(s):  
Wood Species ◽  
Extractive Content

scholarly journals Enhancement of the physical and mechanical properties of wood using a novel organo-montmorillonite/hyperbranched polyacrylate emulsion

Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jianfeng Xu ◽  
Xiaoyan Li ◽  
Ling Long ◽  
Ru Liu
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Pinus Radiata ◽  
Wood Sample ◽  
Wood Cell Wall ◽  
Physical And Mechanical Properties ◽  
Radiata Pine ◽  
Compact Structure ◽  
Populus Cathayana ◽  
Modified Wood

AbstractIn this work, a novel waterborne hyperbranched polyacrylate (HBPA) dispersed organo-montmorillonite (OMMT) emulsion was synthesized and used for the treatment of wood in a vacuum environment in order to enhance the physical and mechanical properties of the wood. The sapwood of Cathay poplar (Populus cathayana Rehd.) and Radiata pine (Pinus radiata D.Don) were used as the samples for experimentation. The results showed that the physical and mechanical properties of the wood improved significantly due to the successful penetration of the OMMT and HBPA into the wood cell wall. From it was also observed that OMET completely exfoliated from the HBPA matrix and formed a hydrophobic film covering on the inside walls of the cell lumen. Further, it was observed that the poplar sample displayed better mechanical properties than the pine sample because the pine has a more compact structure when compared to poplar and contains rosin. Furthermore, it was also observed that the mechanical properties of the modified wood sample gradually improved with an increase in the concentration of the emulsion. However, excessive concentration (>4 wt%) did not lead to further improvement.

scholarly journals Safety and Effectiveness of Additional Apical Preparation using a Rotary Heat-treated Nickel–Titanium file with Larger Diameter and Minimum Taper in Retreatment of Curved Root Canals

2021 ◽  
Author(s):  
Jader Camilo Pinto ◽  
Fernanda Ferrari Esteves Torres ◽  
Airton Oliveira Santos-Junior ◽  
Marco Antonio Hungaro Duarte ◽  
Juliane Maria Guerreiro-Tanomaru ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Continuous Wave ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Filling Material ◽  
Root Canals ◽  
Filling Materials ◽  
Heat Treated ◽  
Before And After ◽  
Curved Root Canals

Abstract Objective The aim of this study was to investigate the effect of additional apical preparation using the ProDesign Logic (PDL) 50/.01 rotary heat-treated nickel–titanium (NiTi) file with a larger diameter and minimal taper for retreatment of curved root canals. Materials and Methods Mesial curved root canals of 12 mandibular molars were prepared using PDL 25/.06 and filled using the continuous wave of condensation technique and AH Plus sealer. After retreatment using ProDesign S (PDS) 25/.08, PDL 25/.06 and PDL 35/05, a complementary procedure was performed with PDL 50/.01. Microcomputed tomography (micro-CT) scanning was performed before and after retreatment procedures. The cyclic fatigue resistance of unused PDS 25/.08, PDL 25/.06, PDL 35/.05 and PDL 50/.01 instruments (n = 12) was evaluated in a stainless-steel device. Statistical Analysis Data on the volumes of the root canals and the remaining filling materials were submitted to the paired t-test. Cyclic fatigue resistance data was submitted to one-way ANOVA and Tukey’s tests (α = 0.05). Results Use of PDL 50/.01 decreased the remaining filling materials in the apical third (p < 0.05). The root canal volume was similar in the cervical and middle thirds before and after preparation using PDL 50/.01 (p > 0.05). PDL 50/.01 presented the highest cyclic fatigue resistance (p < 0.05). Conclusions Use of the PDL 50/.01 instrument as an additional apical preparation for retreatment of curved root canals improved filling material removal in the apical third, while maintaining the dentin in the cervical and middle thirds. In addition, PDL 50/.01 presented high-flexural resistance.

Colour stability of surface finishes on thermally modified beech wood

2021 ◽  
Vol 114 ◽  
pp. 116-124
Author(s):  
Gabriela Slabejová ◽  
MÁRIA ŠMIDRIAKOVÁ
Keyword(s):  
Surface Finish ◽  
Beech Wood ◽  
Surface Finishing ◽  
Colour Stability ◽  
Colour Difference ◽  
Surface Finishes ◽  
Before And After ◽  
Thermally Modified Wood ◽  
Wood Surfaces ◽  
Modified Wood

Colour stability of surface finishes on thermally modified beech wood. The paper deals with the influence of the type of transparent surface finish on the change of colour of the surfaces of native beech wood and thermally modified wood. At the same time, the colour stability of three surface finishes on the surfaces of native and thermally modified beech wood was monitored. Beech wood was thermally modified at temperature of 125 °C for 6 hours. The thermal treatment was performed in a pressure autoclave APDZ 240, by the company Sundermann s.r.o in Banská Štiavnica. Three various types of surface finishes (synthetic, wax-oil, water-based) were applied onto the wood surfaces. The colour of the surfaces of native wood and thermally modified wood was measured in the system CIELab before and after surface finishing; the coordinates L*, a*, b*, C*ab and h*ab were measured. From the coordinates measured before and after surface finishing, the differences were calculated and then the colour difference ∆E* was calculated. Subsequently, the test specimens with the surface finishes were exposed to natural sunlight, behind glass in the interior for 60 days. The surface colour was measured at specified time of the exposure (10, 20, 30, 60 days). The results showed that the colour of the wood surfaces changed after application of the individual surface finishes; and the colour difference reached a change visible with a medium quality filter up to a high colour difference. The wax-oil surface finish caused a high colour difference on native wood and on thermally modified wood as well. On native beech wood, the lowest colour difference after exposure to sunlight was noticeable on the synthetic surface finish. On the surface of wood thermally modified, after exposure to sunlight, the lowest colour difference was noticeable on the surface with no surface finish.

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