Preparation of Particleboard Made from Wheat Straw with Low-Formaldehyde-Emission Composite Adhesive

2011 ◽  
Vol 181-182 ◽  
pp. 406-409
Author(s):  
Yan Hua Zhang ◽  
Ji You Gu ◽  
Xin Ying Lv ◽  
Ming Wei Di ◽  
Hai Yan Tan
Keyword(s):  
Wheat Straw ◽  
Reaction Temperature ◽  
Formaldehyde Emission ◽  
Blocking Agent ◽  
Blocking Agents ◽  
Uf Resin ◽  
Low Emission ◽  
Wheat Straw Particleboard

This research attempted to prepare the E0 type wheat straw particleboards with low emission formaldehyde composite adhesive. The composite adhesive combined UF resin and blocked polyisocyanate with low deblocked temperature was synthesized with sodium bisulphate as blocking agent. The effects of different blocking agents, mol ratio, reaction temperature and time on block reaction were studied. The influence of mixed ratio of composite adhesive on the performance of wheat straw particleboard was investigated.

Effect of Processing Parameters on Properties of Wheat-Straw Boards with FRW

2011 ◽  
Vol 250-253 ◽  
pp. 947-950
Author(s):  
Xiao Dong Zhu ◽  
Feng Hu Wang ◽  
Yu Liu
Keyword(s):  
Wheat Straw ◽  
Processing Condition ◽  
Fire Retardant ◽  
Physical And Mechanical Properties ◽  
Processing Parameters ◽  
Resin Content ◽  
National Standard ◽  
Appearance Time ◽  
Uf Resin ◽  
Peak Value

This paper explored the effect of MDI, UF and FRW content on the mechanical and fire retardant property of straw based panels with surface alkali liquor processing. In order to manufacture the straw based panel with high quality, low toxic and fire retardant, the interface of wheat-straw was treated with alkaline liquid under the optimal treating condition: alkaline liquid concentration was 0.4-0.8%, alkaline dosage was 1:2.5-1:4.5, alkaline-treated time was 12h-48h.The physical and mechanical properties of wheat-straw boards after treated could satisfy the China national standard. And the variance analysis of the fire retardant property of straw based panel showed that TTI, pkHRR and peak value appearance time were not affected by the MDI, UF and FRW content significantly. The results of orthogonal test showed that the optimized processing condition was MDI content as 4%, UF resin content as 7% and the FRW content as 10%.

Preparation and Characteristic of Urea Formaldehyde Modified with Hexamethoxymethyl Melamine

2010 ◽  
Vol 160-162 ◽  
pp. 1245-1252
Author(s):  
Zhen Zhong Gao ◽  
Li Tao Guan ◽  
Jin Sun ◽  
Deng Yun Tu
Keyword(s):  
Bond Strength ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Solidification Time ◽  
Uf Resin ◽  
Optimum Formulation ◽  
Chinese Standard

Hexamethoxymethyl melamine (HMMM) was used to modify UF resins to obtain good performance with low formaldehyde emission. The effect of urea to formaldehyde ratio, HMMM content on the properties of UF resin was studied in detail. The results suggested that urea to formaldehyde ratio to be 1:0.9 and 20% HMMM content is the optimum formulation to afford desired UF resin. The viscosity, solidification time, bond strength and formaldehyde emission of the modified UF resins were also studied. The results revealed that the performance of the modified UF achieved the chinese standard.

Fractionation of the motor unit: response to tetanus

1961 ◽  
Vol 200 (4) ◽  
pp. 689-693
Author(s):  
Simeon Locke
Keyword(s):  
Action Potential ◽  
Motor Unit ◽  
Nerve Terminal ◽  
Differential Effect ◽  
Blocking Agent ◽  
Single Motor Unit ◽  
Single Motor ◽  
Blocking Agents ◽  
Before And After ◽  
Post Tetanic Potentiation

The effect of a tetanus on the motor unit of the gastrocnemius of the rat has been studied before and after administration of blocking agents. Post-tetanic potentiation of action potential of the single motor unit occurs following depression of response by curare or decamethonium. Increased amplitude of unit potential results from partial resynchronization of subunit potential contributions which had been desynchronized by the differential effect of the blocking agent on subunit latency. Decline of unit potential subsequent to post-tetanic potentiation results from desynchronization of component contributions as had been observed with initial administration of blocking agent. The occurrence of these events in a single motor unit indicates that they take place at the nerve terminal or subterminal portion of the unit.

The Effect Of Weight Fraction And Size On The Properties Of Sago Particles Urea Formaldehyde Particleboard

2015 ◽  
Vol 73 (1) ◽  
Author(s):  
Tay Chen Chiang ◽  
Sinin Hamdan ◽  
Mohd Shahril Osman
Keyword(s):  
Urea Formaldehyde ◽  
Great Influence ◽  
Single Layer ◽  
Weight Fraction ◽  
Solid Content ◽  
Wood Products ◽  
Density Level ◽  
Testing Method ◽  
Uf Resin ◽  
Low Emission

We live in a world where wood products are hard to ignore. The sheer flexibility in the number of applications where the wood is used means that it is one of the most sought resources in the world. The wood products industry faces challenges in promoting sustainable management of forest resources. Composite materials have advantage of having an optimized performance, minimized weight and volume, cost effectiveness, chemical resistance and resistance to biodegradation. The research in this paper is focused on sago particles with adhesive of low emission urea formaldehyde (UF) resin 51.6% solid content. The fabrication and testing method are based on JIS A 5908 standard. A single-layer particleboard by using the sago particles has been established at targeted density level 600kg/m3. Particles with weight fractions of 90%, 85%, 80%, 75% and 70% were used in the fabrication of sago composite boards. The results of the test demonstrated that the samples with different weight fraction and size have great influence on the mechanical properties like: MOR, screw test and internal bonding. The findings had demonstrated that the level of weight fraction and size had affects the performance of a board. At the next stage of the research the comparison between sago and wood particleboard will be carried out to identify the feasibility of these materials in the industrial application.

Preparation of Activated Carbon from Formic Acid Hydrolysis Residue by Chemical Activation of ZnCl2

2013 ◽  
Vol 860-863 ◽  
pp. 527-533
Author(s):  
Zhen Wu ◽  
Yong Sun ◽  
Lei Hu ◽  
Ning Xu ◽  
Ben Lin Dai
Keyword(s):  
Response Surface Methodology ◽  
Activated Carbon ◽  
Formic Acid ◽  
Acid Hydrolysis ◽  
Wheat Straw ◽  
Response Surface ◽  
Reaction Temperature ◽  
Preparation Conditions ◽  
Formic Acid Hydrolysis ◽  
Hydrolysis Residue

Utilization of wheat straw for bio-based chemicals production is a research focus. In this work, experiments were conducted to study the preparation conditions of activated carbon from formic acid hydrolysis residue of wheat straw applying response surface methodology. The effects of activation reaction temperature, retention time and activator quantity on the decolorizing capacity of activated carbon were dealt with in this paper. Optimal preparation conditions were abtained by response surface methodology as followed: the content of ZnCl2 solution was 14.2%, reaction temperature was 798°C and retained time was 30 mins with a decolorizing capacity of 15.8 mL methylene blue. Results indicated that the technology was available.

Potential of pulp and paper sludge as a formaldehyde scavenger agent in MDF resins

Holzforschung ◽  
2011 ◽  
Vol 65 (3) ◽  
Author(s):  
Sébastien Migneault ◽  
Ahmed Koubaa ◽  
Bernard Riedl ◽  
Hamid Nadji ◽  
James Deng ◽  
...  
Keyword(s):  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Length Distribution ◽  
Formaldehyde Emission ◽  
Buffering Capacity ◽  
Pulp And Paper ◽  
Adhesive Properties ◽  
Bending Performance ◽  
Fiber Length Distribution ◽  
Uf Resin

Abstract Sludge of pulp and paper mills have natural adhesive properties. The primary sludge (PS, contains fibers) and secondary sludge (SS, contains proteins) could also be suitable for manufacturing medium-density fiberboard (MDF). Protein in SS can react with formaldehyde (HCHO), and as an additive in urea-formaldehyde (UF) resins it can reduce formaldehyde emission. Thus, SS was investigated in the present study. PS and SS were collected from two mills and characterized in terms of chemical composition, fiber length distribution, pH, and buffering capacity. MDF samples were processed according to an experimental design, in which UF resin content was reduced from 12% to 8% and replaced by SS in the range of 5%–15%. Gel time measurement showed high SS reactivity with UF resin. The SS reduced HCHO emissions by up to 68% compared to control panels, without compromising internal bond strength. The bonding effect of SS was lower than expected due to the high pH, thus the buffering capacity reduced UF performance. Moreover, sludge reduced bending performance. Dimensional stability was the greatest disadvantage of sludge panels.

Increased Sensitivity to Depolarizing and Nondepolarizing Neuromuscular Blocking Agents in Young Rat Hemidiaphragms

2001 ◽  
Vol 95 (2) ◽  
pp. 478-484 ◽  
Author(s):  
L. Philippe Fortier ◽  
Richard Robitaille ◽  
François Donati
Keyword(s):  
Neuromuscular Junctions ◽  
Relative Sensitivity ◽  
Optimal Dose ◽  
Blocking Agent ◽  
Neuromuscular Blocking ◽  
Neuromuscular Blocking Agents ◽  
Response Curves ◽  
Potency Ratio ◽  
Blocking Agents ◽  
Increased Sensitivity

Background Newborn neuromuscular junctions are more sensitive to d-tubocurarine than more mature preparations. It is unclear whether the same modifications occur with newer nondepolarizing agents and depolarizing agent succinylcholine. The purpose of this study was to determine the relative sensitivity of newborn neuromuscular junctions to succinylcholine and five nondepolarizing agents. Methods The phrenic nerve-hemidiaphragm preparation from 60 rats was used, 30 aged 9-12 days (newborn) and 30 aged 27-33 days (adult). Five rats from each group were exposed to one of six neuromuscular blocking agents (d-tubocurarine, cisatracurium, atracurium, vecuronium, rocuronium, and succinylcholine). Indirectly elicited twitch tension was measured during control conditions in the absence of blocking agent, followed by four concentrations of one of the six agents. Concentration-response curves were constructed and the EC50 (concentration required to produce 50% depression of twitch tension) was obtained. Potency ratios (EC50adult/EC50newborn) were derived for each agent. Results Newborn preparations were significantly (P < 0.001) more sensitive than their adult counterparts for all six agents tested. For nondepolarizing agents, the potency ratio was in the 6-12 range. The EC50adult/EC50newborn were as follows, in decreasing potency order: d-tubocurarine, 1.68/0.23 microM; cisatracurium, 2.73/0.47 microM; vecuronium, 5.47/0.59 microM; rocuronium, 9.7/0.78 microM; and atracurium, 12.3/1.9 microM. Succinylcholine was three times as potent in newborn rats, with an EC50adult/EC50newborn of 21.3/7.3 microM. The ratio for succinylcholine was significantly less than for all nondepolarizing drugs (P < 0.02). Conclusion The newborn neuromuscular junction of the rat shows an increased sensitivity to all neuromuscular blocking agents tested, including succinylcholine. However, the potency ratio was greater for nondepolarizing than depolarizing drugs. The optimal dose of these agents for certain situations such as cesarean section and anesthesia in neonates should be reassessed.

Effect of thiol blocking agents on the binding of T3 and T4 in rat liver nuclear extract

1981 ◽  
Vol 98 (1) ◽  
pp. 68-72 ◽  
Author(s):  
J. Knopp ◽  
J. Brtko
Keyword(s):  
Binding Sites ◽  
Specific Binding ◽  
Nuclear Extract ◽  
Blocking Agent ◽  
Binding Affinities ◽  
Structural Configuration ◽  
Blocking Agents ◽  
Nuclear Extracts ◽  
Liver Nuclei ◽  
Apparent Association

Abstract. Liver nuclei bind thyroid hormones (T3 and T4) with different binding affinities. In our studies it was estimated that the apparent association constant (Ka) in the liver nuclei for T3 was 8.8 × 1010 l mol−1 and for T4 was 4.1 × 109 l mol−1. We have found that the binding sites for T4 are also saturated by an excess of unlabelled T4 and that saturation was dependent on the purification step of liver binding proteins. In liver nuclear extracts with 0.4 mol l−1 KCl the specific binding of T3 and T4 was blocked with a typical -SH blocking agent N-ethylmaleinimide (NEM) and by new types of -SH blocking agents such as p-bromphenylisothiocyanate (p-BPI) and 2,3 dicyano-1,4-dithio-9,10 antrachinone (Delan). NEM and p-BPI increased the non-specific binding of T4 and completely abolished specific binding. All these agents blocked the specific binding of T3. These results demonstrate that T3 and T4 binding sites in the liver nuclei may not be altogether identical and that the different effects of -SH blocking agents on the binding of T3 and T4 is probably associated with the structural configuration of these drugs.

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