scholarly journals Pretreatment of kraft lignin by deep eutectic solvent and its utilization in preparation of lignin-based phenolic formaldehyde adhesive

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3103-3120
Author(s):  
Xiteng Xian ◽  
Shubin Wu ◽  
Wenguang Wei ◽  
Fengshan Zhang
Keyword(s):  
Bond Strength ◽  
Phenol Formaldehyde ◽  
Control Sample ◽  
Deep Eutectic Solvent ◽  
Kraft Lignin ◽  
National Standard ◽  
Experimental Conditions ◽  
Substitution Degree ◽  
Coniferous Wood ◽  
Methoxy Content

To improve the reactive sites of kraft technical lignin, a deep eutectic solvent (DES) composed of ZnCl2 / lactic acid was used to pretreat kraft lignin from coniferous wood. The modified and unmodified lignin were used to replace different proportions of phenol (50%, 60%, and 70%) to prepare the lignin-phenol-formaldehyde (LPF) adhesive. The phenolic hydroxyl content of DES-treated lignin increased from 3.12 wt% to 3.93 wt% and methoxy content decreased from 11.83 wt% to 6.64 wt% under optimized experimental conditions. The bond strength of LPF adhesive prepared by DES reagent activated lignin was higher than that of the control sample. When the substitution degree of modified lignin for phenol reached 70%, the bond strength of the plywood prepared by the DES-pretreated lignin was 0.79 MPa and the free formaldehyde content was 0.28%, which met the requirements of the Chinese national standard GB/T 9846 (2015). However, the viscosity was higher than the control sample, and results indicate that DES reagent modification cannot improve the viscosity of LPF resin.

scholarly journals Orthodontic bracket bonding without previous adhesive priming: A meta-regression analysis

2015 ◽  
Vol 86 (3) ◽  
pp. 391-398 ◽  
Author(s):  
Aline Segatto Pires Altmann ◽  
Felipe Weidenbach Degrazia ◽  
Roger Keller Celeste ◽  
Vicente Castelo Branco Leitune ◽  
Susana Maria Werner Samuel ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Bond Strength ◽  
Shear Bond Strength ◽  
Outcome Measurement ◽  
Orthodontic Brackets ◽  
Experimental Conditions ◽  
Adhesive Resin ◽  
Meta Regression ◽  
Meta Regression Analysis

ABSTRACT Objective:  To determine the consensus among studies that adhesive resin application improves the bond strength of orthodontic brackets and the association of methodological variables on the influence of bond strength outcome. Materials and Methods:  In vitro studies were selected to answer whether adhesive resin application increases the immediate shear bond strength of metal orthodontic brackets bonded with a photo-cured orthodontic adhesive. Studies included were those comparing a group having adhesive resin to a group without adhesive resin with the primary outcome measurement shear bond strength in MPa. A systematic electronic search was performed in PubMed and Scopus databases. Results:  Nine studies were included in the analysis. Based on the pooled data and due to a high heterogeneity among studies (I2  =  93.3), a meta-regression analysis was conducted. The analysis demonstrated that five experimental conditions explained 86.1% of heterogeneity and four of them had significantly affected in vitro shear bond testing. The shear bond strength of metal brackets was not significantly affected when bonded with adhesive resin, when compared to those without adhesive resin. Conclusions:  The adhesive resin application can be set aside during metal bracket bonding to enamel regardless of the type of orthodontic adhesive used.

Tack and shear strength of hybrid adhesive systems made of phenol-formaldehyde, dextrin and fish glue, and acrylic pressure-sensitive adhesive

Holzforschung ◽  
2012 ◽  
Vol 66 (1) ◽  
Author(s):  
Amir Sahaf ◽  
Karl Englund ◽  
Marie-Pierre G. Laborie
Keyword(s):  
Shear Strength ◽  
Bond Strength ◽  
Phenol Formaldehyde ◽  
Curing Temperature ◽  
Pressure Sensitive Adhesive ◽  
Pressure Sensitive ◽  
Initial Adhesion ◽  
The Subject ◽  
Block Test ◽  
Shear Block

Abstract The development of adhesives that have good initial adhesion (tack) that provides improved mat integrity during shape-forming of wood composites has been the subject of recent research. Hybrid adhesives were made based on thermosetting phenol-formaldehyde (PF), to which three tacky adhesives were added: high tack fish glue (FG), dextrin glue (DX) and a commercial acrylic, pressure-sensitive adhesive (PSA). Tacky adhesives were blended with PF at weight levels of 25%, 50% and 75%. The time-dependent tack development of the resulting hybrid adhesives was evaluated by means of a texture analyzer. The bond strength of adhesives was measured after curing by shear block test. PF/DX blends exhibited the highest tack during longer open times, while blends of PF and FG had low tack during shorter times. PF/PSA blends lost their bond strength completely after being heated at the curing temperature of PF. PF/FG blends did not show a significant decrease in bond strength compared to pure PF. The addition of DX had no effect on shear strength at ratios <75%.

Study on on-Line Detecting of Total Phosphorus by Nano-TiO2-UV Photoelectron-Catalysis Oxidation Method

2011 ◽  
Vol 694 ◽  
pp. 298-303 ◽  
Author(s):  
Mo Jie Sun ◽  
Peng Wang ◽  
Yu Han Shan ◽  
Chun Biao Zhang
Keyword(s):  
Ph Value ◽  
Raw Materials ◽  
Sol Gel ◽  
Computer Application ◽  
National Standard ◽  
Tetrabutyl Titanate ◽  
Experimental Conditions ◽  
Conductive Glass ◽  
On Line ◽  
Organophosphorous Compounds

In this paper, we made the nano-TiO2/glass composite electrode through the sol-gel method by using tetrabutyl titanate and anhydrous alcohol as the raw materials and the ITO conductive glass as the carrier. With the help of the photoelectric catalytic effect of TiO2 and the strong oxidation of Na2S2O8 as well as the computer application technology, we decomposed rapidly of the organophosphorous compounds and detected the total phosphorous (TP) on-line accurately. And then we characterized the TiO2 particles by SEM and analyzed the factors which influenced the decomposition and detection of TP by this method. The results show that the optimum experimental conditions of this method should be as follow: the concentration of Na2S2O8 is 0.03mol/L, UV illuminating time is 10 min, electrode voltage is 8V and the pH value should be in the alkaline zone. At last, it is validated the method is reliable and accurate for the decomposition of the organophosphorous by the recovery experiments and the comparative experiments between this method and national standard method.

Synthesis of 5-Hydroxymethylfurfural-Acetone Resins

2021 ◽  
Vol 887 ◽  
pp. 17-22
Author(s):  
Ekaterina A. Shabliy ◽  
Victor A. Klushin ◽  
Nina V. Smirnova
Keyword(s):  
Renewable Resources ◽  
Water Resistance ◽  
Raw Materials ◽  
Phenol Formaldehyde ◽  
Condensation Reaction ◽  
Agricultural Waste ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Experimental Conditions ◽  
Synthesis Conditions

5-hydroxymethylfurfural-acetone (5-HMFA) resins are obtained on the basis of 5-hydroxymethylfurfural (5-HMF) and acetone, that is, from monomers whose source of raw materials is renewable resources (agricultural waste). The 5-HMFA condensation reaction was carried out under various experimental conditions. The synthesis conditions for 5-HMFA were selected with a yield of the desired product of 51%. The resulting resins were pressed at various curing temperatures and tested for compressive strength and absorption of water. The optimum pressing temperature was set to 180 ° C. The resulting composites have a strength not inferior to the strength of phenol-formaldehyde resin composites, but have a 3 times higher water resistance.

scholarly journals Modeling and Optimization of Phenol Formaldehyde Resin Sand Mould System

2017 ◽  
Vol 17 (2) ◽  
pp. 162-170 ◽  
Author(s):  
G. R. Chate ◽  
M. G. C. Patel ◽  
M. B. Parappagoudar ◽  
A. S. Deshpande
Keyword(s):  
Phenol Formaldehyde ◽  
Desirability Function ◽  
Process Analysis ◽  
Statistical Significance ◽  
Setting Time ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Experimental Conditions ◽  
Sand Mould ◽  
Green Sand Mould System

AbstractChemical bonded resin sand mould system has high dimensional accuracy, surface finish and sand mould properties compared to green sand mould system. The mould cavity prepared under chemical bonded sand mould system must produce sufficient permeability and hardness to withstand sand drop while pouring molten metal through ladle. The demand for improved values of permeability and mould hardness depends on systematic study and analysis of influencing variables namely grain fineness number, setting time, percent of resin and hardener. Try-error experiment methods and analysis were considered impractical in actual foundry practice due to the associated cost. Experimental matrices of central composite design allow conducting minimum experiments that provide complete insight of the process. Statistical significance of influencing variables and their interaction were determined to control the process. Analysis of variance (ANOVA) test was conducted to validate the model statistically. Mathematical equation was derived separately for mould hardness and permeability, which are expressed as a non-linear function of input variables based on the collected experimental input-output data. The developed model prediction accuracy for practical usefulness was tested with 10 random experimental conditions. The decision variables for higher mould hardness and permeability were determined using desirability function approach. The prediction results were found to be consistent with experimental values.

scholarly journals Bond Strength of a Bisphenol-A-Free Fissure Sealant With and Without Adhesive Layer under Conditions of Saliva Contamination

2016 ◽  
Vol 27 (3) ◽  
pp. 309-312
Author(s):  
Késsia Suênia Fidelis de Mesquita-Guimarães ◽  
Iliana Ferraz Sabbatini ◽  
Cintia Guimarães de Almeida ◽  
Rodrigo Galo ◽  
Paulo Nelson-Filho ◽  
...  
Keyword(s):  
Bond Strength ◽  
Testing Machine ◽  
Adhesive Layer ◽  
Adhesive System ◽  
Human Saliva ◽  
Experimental Conditions ◽  
Fissure Sealant ◽  
Carious Lesions ◽  
Saliva Contamination ◽  
System F

Abstract Dental sealants are important for prevention of carious lesions, if they have good shear strength. The aim of this study was to evaluate the shear bond strength (SBS) of two sealants to saliva-contaminated and non-contaminated enamel with and without an intermediate adhesive layer underneath the sealant. Ninety flat enamel surfaces from human third molars were randomly assigned to 6 groups (n=15): F (control): Fluroshield(tm) sealant; EWB (control): Embrace(tm) WetBond(tm); SB/F: Single Bond adhesive system + F; SB/EWB, s-SB/F and s-SB/EWB. In the s-SB/F and s-SB/EWB groups, the acid-etched enamel was contaminated with 0.01 mL of fresh human saliva for 20 s. Sealant cylinders were bonded to enamel surface with and without an intermediate adhesive system layer. The shear tests were performed using a universal testing machine (0.5 mm/min). Data were analyzed statistically by Kruskal-Wallis and Mann-Whitney tests (α=0.05). F presented higher mean SBS than EWB in all experimental conditions. The lowest SBS mean was obtained for EWB on contaminated enamel (p<0.05). In conclusion, an adhesive system layer should be used prior to sealant placement, in both dry and saliva-contaminated enamel. F had the best performance in all experimental conditions. EWB sealant showed very low results, but an adhesive layer underneath the sealant increased its SBS even after salivary contamination.

scholarly journals A selective laser melted Co-Cr alloy used for the rapid manufacture of removable partial denture frameworks: Initial screening of biocompatibility

2011 ◽  
Vol 76 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Danimir Jevremovic ◽  
Vesna Kojic ◽  
Gordana Bogdanovic ◽  
Tatjana Puskar ◽  
Dominic Eggbeer ◽  
...  
Keyword(s):  
Mtt Assay ◽  
Control Sample ◽  
L929 Cell ◽  
Cell Number ◽  
Experimental Conditions ◽  
Removable Partial Denture ◽  
Partial Denture ◽  
Agar Diffusion ◽  
Agar Diffusion Test ◽  
Rapid Manufacture

The aim of this study was to determine the cytotoxicity of a Co-Cr alloy used for the rapid manufacture of removable partial denture frameworks using murine fibroblasts L929 cell lines and three test methods: the MTT assay, the agar diffusion test (ADT) and the dye exclusion test (DET). Two groups of disc specimens (5 mm diameter, 1 mm thick) were fabricated. The first group was cast using a conventional method (CM) in a Nautilus CC casting. The second group was fabricated using selective laser melting (SLM) in SLM Realiser The total cell number and viability of cells pre-incubated with CM and SLM alloys were comparable to the control sample. Differences between the growth inhibitory effects of the CM and SLM alloys in the MTT assay were below 30 %. Results of two independent agar diffusion tests with CM and SLM alloys showed neither detectable discoloration around or under the discs nor a detectable difference in staining intensity. As the cell response for both CM and SLM alloys was 0/0, the discs can be rated as noncytotoxic. The results suggested that the F75 Co-Cr alloy used for the SLM process did not release harmful material that could cause acute effects against L929 cells under the given experimental conditions.

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