Preparation of Environmentally Friendly Urea-Hexanediamine-Glyoxal(HUG)Resin Wood Adhesive

Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(UG)resins prepared by just using glyoxal instead of formaldehyde usually yields a lower degree of polymerization.This results in a poorer bonding performance and water resistance of UG resins.A good solution is to pre-react urea to preform polyurea molecules presenting already a certain degree of polymerization,and then to condense these with glyoxal to obtain a novel UG resin.Therefore,in this present work,the urea was reacted with hexamethylene diamine to form a polyurea named HU,and then this was used to react it with different amounts of glyoxal to synthesize hexamethylenediamine-urea-glyoxal(HUG)polycondensation resins,and to use this for bonding plywood.The results show that the glyoxal can well react with HU polyuria via addition and schiff base reaction,and also the HUG resin exhibits excellent bonding strength and water resistance.The shear strength of the plywood bonded with this HUG at 160°C hot press temperature as high as 1.93 MPa,2.16 MPa and 1.61 MPa,respectively,which meets the requirement of the China national standard GB/T 9846-2015(≥0.7 MPa),and can be a good choice as a wood adhesive for industrial application.

Research progress and application prospect of functional adhesive materials in the field of oil and gas drilling and production

By summarizing the composition,classification,and performance characterization of functional adhesive materials,the adhesion mechanisms of functional adhesive materials,such as adsorption/surface reaction,diffusion,mechanical interlocking,and electrostatic adsorption,are expounded.The research status of these materials in oil and gas drilling and production engineering field such as lost circulation prevention/control,wellbore stabilization,hydraulic fracturing,and profile control and water plugging,and their application challenges and prospects in oil and gas drilling and production are introduced comprehensively.According to the applications of functional adhesive materials in the field of oil and gas drilling and production at this stage,the key research directions of functional adhesive materials in the area of oil and gas drilling and production are proposed:(1)blending and modifying thermoplastic resins or designing curable thermoplastic resins to improve the bonding performance and pressure bearing capacity of adhesive lost circulation materials;(2)introducing low-cost adhesive groups and positive charge structures into polymers to reduce the cost of wellbore strengthening agents and improve their adhesion performance on the wellbore;(3)introducing thermally reversible covalent bond into thermosetting resin to prevent backflow of proppant and improve the compressive strength of adhesive proppant;(4)introducing thermally reversible covalent bonds into thermoplastic polymers to improve the temperature resistance,salt-resistance and water shutoff performance of adhesive water shutoff agents.

Removal of adhesive dusts from flue gas using corona discharges with spraying water

Effective removal of adhesive and fine dusts from flue gas is very difficult. A new method of electrostatic precipitation of the corona discharges with spraying water(CDSW) was introduced. A new electrode configuration and the circulation spraying of water were employed in the method. The efficient electrostatic precipitation for adhesive and fine dusts can be accomplished without any drain water during a long operating period. The fundamental structure, discharge characteristics, mechanism of spraying and precipitation principle of the electrostatic precipitation using CDSW were described and analyzed. The V I characteristics, spraying state, supplying water quantity, influence of temperature and clean of the electrodes were researched in series experiments. The treating effects of circulating spraying using the corona plasma at the same time of electrostatic precipitation were investigated. The fundamental theories and experimental data were proposed, in order to effectively remove the adhesive dusts from flue gas using CDSW in practice.

State of Research and Trends in the Development of Polyvinyl Acetate-Based Wood Adhesive

Synthetic wood adhesives, consisting of urea-formaldehyde resins (UF), phenol-formaldehyde resins (PF), melamine-formaldehyde resins (MF), and polyurethane resins, are widely used. For UF and MF, most investigations are concerned with reducing free formaldehyde content;for PF, most studies focused on finding new alternative chemicals to replace phenol. These adhesives come under the Carcinogenic, Mutagenic, and Reprotoxic chemicals (CMR) category. Due to global energy issues and dependency on petroleum sources, the focus has shifted to look for alternative and renewable raw material sources for wood adhesives. Conventionally available wood adhesives are polyvinyl alcohol (PVA) stabilized, with drawbacks like poor water resistance, poor heat resistance, low-temperature workability, and it’s based on petroleum resources. Polyvinyl acetate (PVAc) is non-resistant to moisture polymer, and if such adhesive joints are exploited in a moist environment, its strength substantially decreases. Sufficiently moisture-resistant adhesive joints are obtained by modifying PVAc dispersion with special compounds like reactive comonomer, Silanes, and modified PVA. To improve the workability at low temperature, Vinyl acetate (VAc) is copolymerized with specific comonomers like butyl acetate without affecting the performance properties. Here, we aim to present an overview of the research trend of PVAc-based adhesives in the wood industry. The review summarizes the current state of research PVAc-based adhesives.

Adverse effects of metal exposure on chemotaxis towards water-soluble attractants regulated mainly by ASE sensory neuron in nematode Caenorhabditis elegans

Chemotaxis to water-soluble attractants is mainly controlled by ASE sensory neuron whose specification is regulated by che-1 in Caenorhabditis elegans. Our data suggested that exposure to high concentrations of metals, such as Pb, Cu, Ag, and Cr, would result in severe defects of chemotaxis to water-soluble attractants of NaCl, cAMP, and biotin. Moreover, the morphology of ASE neuron structures as observed by relative fluorescent intensities and relative size of fluorescent puncta of cell bodies, relative lengths of sensory endings in ASE neurons, and the expression patterns of che-1 were obviously altered in metal exposed animals when they meanwhile exhibited obvious chemotaxis defects to water-soluble attractants. In addition, the dendrite morphology could be noticeably changed in animals exposed to 150 μmol/L of Pb, Cu, and Ag. Furthermore, we observed significant decreases of chemotaxis to water-soluble attractants in Pb exposed che-1 mutant at concentrations more than 2.5 μmol/L, and in Cu, Ag, and Cr exposed che-1 mutant at concentrations more than 50 μmol/L. Therefore, impairment of the ASE neuron structures and functions may largely contribute to the appearance of chemotaxis defects to water-soluble attractants in metal exposed nematodes.

New insights into the deposition of natural gas hydrate on pipeline surfaces:A molecular dynamics simulation study

Natural gas hydrate(NGH)can cause pipeline blockages during the transportation of oil and gas under high pressures and low temperatures.Reducing hydrate adhesion on pipelines is viewed as an efficient way to prevent NGH blockages.Previous studies suggested the water film can greatly increase hydrate adhesion in gas-dominant system.Herein,by performing the molecular dynamics simulations,we find in water-dominant system,the water film plays different roles in hydrate deposition on Fe and its corrosion surfaces.Specifically,due to the strong affinity of water on Fe surface,the deposited hydrate cannot convert the adsorbed water into hydrate,thus,a water film exists.As water affinities decrease(Fe>Fe_(2)O_(3)>FeO>Fe_(3)O_(4)),adsorbed water would convert to amorphous hydrate on Fe_(2)O_(3)and form the ordered hydrate on FeO and Fe_(3)O_(4)after hydrate deposition.While absorbed water film converts to amorphous or to hydrate,the adhesion strength of hydrate continuously increases(Fe<Fe_(2)O_(3)<FeO<Fe_(3)O_(4)).This is because the detachment of deposited hydrate prefers to occur at soft region of liquid layer,the process of which becomes harder as liquid layer vanishes.As a result,contrary to gas-dominant system,the water film plays the weakening roles on hydrate adhesion in water-dominant system.Overall,our results can help to better understand the hydrate deposition mechanisms on Fe and its corrosion surfaces and suggest hydrate deposition can be adjusted by changing water affinities on pipeline surfaces.

Influencing Factors of Fabric-Skin Adhesion Based on Gray Correlation Analysis Method

Fabric-skin adhesion was objectively described by the indices of the maximum adhesion force F_(max) , the maximum separation distance L_(max) ,and adhesion work W as well as the adhesion force-separation distance curve. Firstly,gray correlation analysis method was adopted to investigate the correlation levels between adhesion indices,and secondly the relative importance of fabric structural parameters to fabric-skin adhesion,as well as the correlation levels between skin adhesion, water absorption, and wicking properties of the fabric. The results prove that W exhibits clear correlations with both F_(max) and L_(max) , yet the relevance between F_(max) and L_(max) is weak. Fabric adhesion indices are most associated with fabric mass and least with fabric thickness,whereas fabric wicking and water absorption present closest correlation with fabric thickness. Therefore, it is concluded that the relevance between fabric wicking, water absorption, and skin-adhesion properties are rather comprehensive than straight.

渗透胁迫对春小麦根质膜H^+-ATP_(ase)活力的影响及其与脯氨酸积累的关系

以会宁 18、陇春 17、陇春 8139、定西 35四个春小麦品种为材料 ,用不同浓度的PEG6 0 0 0溶液模拟干旱胁迫 ,结果发现 :干旱胁迫下 ,抗旱性不同的品种其脯氨酸积累的水分临界点不同 ,脯氨酸的积累对膜结构的完整性具有一定的保护作用 ;抗旱性不同的春小麦品种其根系的H+ ATPase活性在干旱胁迫下的变化趋势也不同 ,抗旱性弱的品种 ,H+ ATPase活性随着胁迫程度的加剧呈降低趋势 ;抗旱性强的品种 ,H+ ATPase活性呈升高趋势 .分析表明 ,H+ ATPase活性与脯氨酸的积累之间呈现显著相关性 ,且H+ ATPase对脯氨酸的积累有一定的正调控作用 .

Prediction of suitable water content in granulation of sintering mixture based on Litster's model

Suitable water content plays a decisive role in the granulation of sintering mixtures.Herein,a method was proposed to predict the suitable water content for effective granulation on the basis of Litster's granulation model.The granulation effectiveness of a sintering mixture was predicted by the model,with the allowance error of±10%.The effects of the water absorption properties,particle size composition and content of adhesive particles on the suitable water content were studied.The results showed that the allowable error of prediction was within±0.5%compared to the experimentally determined suitable water content.With an increase in adhesive powder content of mixtures with higher water absorption,the suitable water content increased to achieve similar granulation effectiveness.Moreover,as the amount of concentrates increased,the suitable water content first increased and then remained steady.The influence of the water absorption characteristics of the adhesive particles on the suitable water content was less than that of their particle size composition in the mixture.

Adhesion forces for water/oil droplet and bubble on coking coal surfaces with different roughness

Surface roughness plays a significant role in floatability of coal.In the present paper,coking coal surface was polished by three different sandpapers and the surface properties were characterized by contact angle and roughness measurements.The effect of surface roughness on floatability was investigated by adhesion force measurement system for measuring interaction forces between droplets/bubbles and coking coal surfaces with different roughness.The results showed that the contact angle decreased with increasing roughness yet the adhesion force between the water droplet and coal surface increased owing to the increased contact line and the appearance of line pinning.Maximum adhesion forces between water and surfaces were 111.70,125.48,and 136.42μN when the roughness was 0.23,0.98,and 2.79 μm,respectively.In contrast,under a liquid environment,the adhesion forces between air bubble/oil droplet and coal surfaces were decreased with increasing roughness because of the restriction by water.Maximum adhesion forces of increasing roughness were 97.14,42.76,and 17.86 μN measured at interfaces between air bubble and coal surfaces and 169.48,145.84,and 121.02 lN between oil droplet and surfaces,respectively.Decreasing roughness could be beneficial to the spreading of oil droplets and the adhesion of bubbles which is conducive to flotation separation.

快速溶剂萃取技术(ASE)在水环境监测中的比较研究及展望

萃取技术是一种样品前处理方法,可以用于水环境等领域的监测。其中较为受推崇的主要是快速萃取技术和固相萃取技术。本文通过快速萃取技术原理的简单分析,重点将其与传统的几种萃取技术进行了比较,并对未来的发展趋势作了简要展望。

Molecular simulation study of the adhesion work for water droplets on water monolayer at room temperature

The wetting phenomenon of water droplets coexisting with the ordered water monolayer termed an unexpected phenomenon of“water that does not wet a water monolayer”at room temperature has been found on several solid surfaces.Although the hydrogen bond saturation inside the monolayer can qualitatively describe this phenomenon,whether the Young-Dupre equation still holds under this unconventional wetting framework is still not answered.In this work,we have´calculated the contact angle values of the droplets as well as the work of adhesion between the droplets and the monolayer based on an extended phantom-wall method.The results show that similar to the conventional solid-liquid interface,classical Young-Dupre equation is also applicable for the interface of liquid water and ordered water monolayer.

Research Progress of Soybean Protein Adhesive:A Review

Traditional formaldehyde-based adhesives rely excessively on petrochemical resources,release toxic gases,and pollute the environment.Plant-derived soybean protein adhesives are eco-friendly materials that have the potential to replace the formaldehyde-based adhesives used to fabricate wood-based panels.However,the poor water resistance,high brittleness,and poor mildew resistance of soybean protein adhesives limit their industrial applications.This article reviews recent research progress in the modification of soybean protein adhesives for improving the bonding performance of adhesives used for wood-based panel fabrication.Modification methods were summarized in terms of water resistance,solid content,and mildew resistance.The modification mechanisms and remaining problems were also discussed.Finally,the current industrial applications and the future research direction of soybean protein adhesives are discussed.

Correlation between Coating Adhesion and Damage Threshold: Simple Method of Reliability Assessment for Optoelectronic Applications

It is demonstrated that inherent coating adhesion and damage threshold are correlated for Ta2O5 and HfO2 coatings widely used in optoelectronic devices. By utilizing a newly proposed 1-h boiling water test combined with the optical aging under high-power laser irradiation, we show that an optical coating that survives the 1-h boiling water test withstands the damage threshold, ensuring the field service life even in harsh environments. Besides the standard evaluation methods, which may have limitations for applications required in harsh environments, the 1-h boiling water test can serve as an alternative method of reliability assessment for optical coatings. A heuristics herein can be used as a gating item for qualification of optical coatings for various applications.

玉米秸秆刨花板压制工艺优化及吸水厚度膨胀率

农作物秸秆用作人造板原材料,可减少环境污染,缓解木材供需紧张,秸秆中纤维素与木质素含量可以满足人造板生产要求。以玉米秸秆刨花为原料,在一定热压压力、热压时间、刨花密度、热压温度下,采用不同施胶量无机胶黏剂压制玉米秸秆刨花板,探索最优工艺参数及玉米秸秆刨花板吸水厚度膨胀率变化规律。结果显示:压制玉米秸秆刨花板的最优工艺参数为刨花含水率12%、热压压力1.6MPa、热压时间9min、刨花密度1.0g/cm^(3)、施胶量20%、热压温度90℃;影响玉米秸秆刨花板吸水厚度膨胀率的因素依次为刨花含水率>热压压力>热压时间>刨花密度>施胶量>热压温度。试验结果表明:在吸水厚度膨胀率合格的前提下,玉米秸秆刨花板的内结合强度、弹性模量、静曲强度均符合国家标准规定的性能要求。

一种新型义齿粘结剂使用效果观察及性能分析

为提高牙科用粘结剂的粘接效果和抗菌性能,试验通过树脂基质、纳米氟化钠和二癸基二甲基氯化铵,制备了一种具有抗菌性能的新型义齿粘结剂,并对二癸基二甲基氯化铵添加量和应用效果进行研究。结果表明,二癸基二甲基氯化铵的添加可以使义齿粘结剂亲水性能和抗菌性能提高,粘接性能下降。当二癸基二甲基氯化铵添加量从1.5%增大到7.5%时,水接触角从80.3°减小到60.5°,剪切粘接强度从15.3 MPa降低到12.2 MPa。二癸基二甲基氯化铵添加量为1.5%或3.0%比较适宜。在应用效果方面,含有3%二癸基二甲基氯化铵和3%纳米氟化钠的新型义齿粘结剂有着良好的粘接性能和抗菌性能。

HEOS治疗宫腔粘连术后预防再粘连3种方法的对比研究

目的 比较3种不同方法在HEOS系统治疗不同程度宫腔粘连术后预防再粘连疗效的研究。方法 分析昆明市妇幼保健院收治的284例的轻中重度宫腔粘连患者,使用HEOS系统治疗后,分为3组,A组(节育环组)放置宫内节育环+透明质酸钠凝胶、B组(球囊组)放置Foley水囊管+透明质酸钠凝胶、C组(对照组)仅放置透明质酸钠凝胶。比较3组术后宫腔粘连恢复情况、月经改善情况、子宫内膜厚度以及术后不良反应。结果轻度宫腔粘连组,月经改善情况中3组比较,差异有统计学意义(P<0.05),A组比C组月经改善率高(对R×C卡方检验两两比较,校正显著水平,P<0.017),其他疗效指标中无显著差异(P>0.017),但A组不良反应率较C组高(P<0.017)。在中度宫腔粘连组,B组的宫腔粘连改善率与其他两组比较有显著差异(P<0.017)。在月经改善率、子宫内膜厚度、不良反应方面,A、B组均较C组增加(P<0.017)。重度宫腔粘连组中,A组各疗效指标均较其他组高(P<0.017)。结论 综合疗效指标和不良反应率分析,对轻、中、重度宫腔粘连,术后依次为放置透明质酸钠凝胶、Foley水囊管+透明质酸钠凝胶、宫内节育环+透明质酸钠凝胶为各程度粘连的最佳选择。达到个体化及分层管理,可取得良好临床效果,值得推广。

不同厂家水基胶挥发性物质的GC-IMS差异分析

目的快速分析不同厂家水基胶中的挥发物特性。方法采用气相色谱-离子迁移谱(GC-IMS)联用技术对各种水基胶中的挥发性物质进行定性分析;结合生物指纹图谱、主成分分析(PCA)法以及欧式距离分析法对不同水基胶样品进行差异对比分析。结果水基胶中共识别出88种挥发性化学物质,涵盖酯类、酮类、醇类、醛类、杂环类、酸类、芳香类、醚类、萜类、酰胺类和腈类等11大类别,其中酯类物质占据显著比例,达26种,占总挥发性物质的38%~46%。结论采用GC-IMS技术结合生物指纹图谱、PCA以及欧式距离分析,能够有效区分不同厂家水基胶样品,同时同一厂家不同规格样品之间显示出较高的相似性;GC-IMS技术为不同厂家水基胶的快速溯源鉴别及挥发性物质差异分析提供了有力工具。

瓷砖胶粘剂在浸水条件下的应用及拉伸胶合性能研究

瓷砖胶粘剂是建筑施工场所常用的材料之一,具有便捷、耐用、安全等优点,为更加合理的添加最优比例的瓷砖胶粘剂的组成配料。分析了浸水条件下外界环境、施工工艺、原料成分等因素对瓷砖胶拉伸胶粘性能影响,分别对比了纤维素醚、级配砂、早强剂、再生砂用量、可再分散乳胶粉等添加剂对瓷砖胶的拉伸粘合性能影响,对瓷砖胶的拉伸胶粘性研究进行综合分析,最后对目前瓷砖胶的性能进行总结和展望。为进一步推动建筑施工用瓷砖胶在浸水条件下的应用制备提供参考。

基于分子动力学聚合物改性沥青黏附性能研究

为了增强基质沥青与集料之间界面黏附性,选取PE、SBS、SBR、PU 4种代表性聚合物对其进行改性,采用分子动力学模拟法对沥青-集料和沥青-水-集料模型进行不同工况模拟,并通过室内试验验证模拟结果。通过分析相对浓度分布曲线得到沥青极性组分的变化规律,研究不同温度下各改性沥青混合料黏附性并根据相对浓度参数对其机理进行分析,通过聚合物改性性能对比,得出其适用条件。结果表明:PE与沥青相溶性好,但PE改性沥青混合料水稳定性较差;SBS改性沥青能在温差较大的环境中保持较高的黏附性;SBR改性沥青低温条件下黏附性突出,且水稳定性优越,适用于低温多雨的地区;PU改性沥青综合性能较好,在高温多雨等气候条件复杂的环境中适用性较强。