高效复合类发泡剂的制备及其性能研究

泡沫混凝土具有容重轻、自立性强及防渗性好等特点,是一种新型港口码头挡土墙回填材料,其中发泡剂的研制对泡沫混凝土的性能起着至关重要的作用。本文制备的发泡剂是以浓度为0.8%的α-烯基磺酸钠溶液为发泡剂母液,选取稳泡物质A、B、C和D对母液进行稳泡改性,并对泡沫性能进行分析研究。该发泡剂制备的泡沫表面光泽细腻,稳定性较好,其中发泡倍数为46.7倍,1 h沉降距为1.2 mm,1 h泌水量为15.7ml,将该发泡剂应用于挡土墙回填用泡沫混凝土,产品表现出了较好的力学性能和抗渗性能。     

Development of a green foaming agent and its performance evaluation

With a view to replace synthetic foaming agents in the production of foam concrete, renewable and naturally available soapnut (SN) fruit has been studied as a foaming agent. Soapnut foaming solutions are prepared in two ways, viz., water soaking for 24 h without heating and with heating of soapnut pericap over a range of temperature (i.e.70 °C–90 °C). The foam generated from the above foaming solutions are studied for properties such as initial foam density and foam stability. However, the use of this foam from soapnut led to cement setting problem, which is caused by the compounds present in soapnut. The setting problem is resolved by using alum as an accelerator. The addition of alum resulted in the formation of additional ettringite and enabled the concrete to set, which is confirmed through powder XRD. The properties of foam concrete produced with water soaked SN with heating is noted to be marginally better compared to those of concrete prepared by water soaked SN without heating. The pore size and shape are analysed using an image analysis technique, which gives good correlations with density and strength of foam concrete.     

石墨泡沫混凝土的吸波性能研究

多功能化和低成本有利于建筑吸波材料的应用。在频率8～18GHz范围内,采用弓形反射法测试了掺加石墨的水泥基泡沫混凝土的吸波性能,研究了石墨掺量、发泡剂用量和试件厚度对石墨泡沫混凝土吸波性能的影响。结果表明,掺加石墨后,泡沫混凝土吸波性能逐渐增强,石墨泡沫混凝土吸波材料中石墨的逾渗阈值为水泥质量的15%;随着发泡剂用量增加,石墨泡沫混凝土反射率逐渐降低。厚度为30mm时,泡沫混凝土吸波性能最佳,当石墨掺量和发泡剂用量分别为水泥质量的15%和2.5%时,反射率降低至-15.64dB,<-10.0dB的带宽可达3.0GHz,导热系数低至0.083W/(m.K)。石墨泡沫混凝土具有良好的保温和吸波性能,可以浇注施工建筑物的屋面和墙体,同时实现建筑电磁辐射防护和建筑节能的目标。     

微纳技术在泡沫混凝土中的应用进展

微纳技术可从多方面提升泡沫混凝土的性能,使二者性能达到完美结合。从泡沫混凝土气孔结构、泡沫混凝土强度、发泡催化剂以及泡沫混凝土电磁屏蔽效应4个方面综述了近年来微纳技术在泡沫混凝土中的应用,分析并展望了泡沫混凝土的前沿技术。     

泡沫混凝土的研究及应用现状

论述了国内外泡沫混凝土的研究应用现状以及取得的一些成果。从泡沫剂的种类,泡沫剂的性能评定,泡沫的制备技术等方面回顾了泡沫剂的研究及应用。探讨了泡沫混凝土中存在的一些缺陷,对泡沫混凝土今后的发展进行了展望。     

原状脱硫石膏泡沫混凝土的制备与性能研究

原状脱硫石膏泡沫混凝土是在自主研发的原状脱硫石膏高强胶凝材料体系的基础上,以H2O2为化学发泡剂,同时在催化剂MnO2的作用下,利用反应后产生的O2达到自主发泡的目的,并掺入一定量的聚丙烯纤维和稳泡剂硬脂酸钙分别起到增强增韧和稳定气泡的作用。实验研究了不同组分对原状脱硫石膏泡沫混凝土各项性能的影响,包括干密度、抗压强度、导热系数、气孔率、线性收缩率、吸水率等性能,并利用扫描电子显微镜观察了不同发泡剂掺量时孔结构的微观形貌,最终确定了最佳配合比:胶凝材料体系组分为1(所包含组分质量比为:m(原状脱硫石膏)∶m(矿渣)∶m(水泥)∶m(石灰粉)∶m(水玻璃)∶m(减水剂)=60∶31∶9∶6∶0.7∶1.8),发泡剂掺量为2.5%、硬脂酸钙为3.2%、纤维为0.15%、水胶比为0.38,均外掺(质量比)。原状脱硫石膏泡沫混凝土各项性能均满足标准JC/T 266-2011《泡沫混凝土》的相关要求。本研究大大扩大了工业废石膏的应用范围,有效节约了自然资源,具有重要的社会现实意义。     

Enhancing the strength of pre-made foams for foam concrete applications

Chemical and mechanical foaming techniques are commonly used in foam concrete technology for developing lightweight construction materials. The characteristics of the foam before the lightweight structure sets and maintains its shape has a great impact on the properties of foamed concretes. The tendency of the foams to coalesce and collapse during the preparation process brings some challenges in controlling the properties of cellular structures. Consequently, it is critical to improve the stability of fresh foams in order to produce high quality cellular structures using a predictable and reliable approach. Aggregating the liquid film around bubbles is known to be effective in improving the stability of foams, but the impact of this stabilizing method has not been investigated for foam concrete applications. In this paper, Xanthan gum (with a thickening capacity) has been utilized as the foam stabilizer to aggregate the liquid film. This stabilizing method is shown to significantly enhance the pore size distribution of foam concretes. The resulting pre-made foams are remarkably more stable than the control foam, and the mechanical properties of the final cellular structure are considerably improved (about 34% in mechanical foaming and 20% in the chemical foaming technique).     

基于复配发泡剂的纸纤维发泡缓冲包装材料制备工艺

以纸质纤维为主料制得的植物纤维基发泡制品,是近年来出现的一种新型缓冲材料。设计了3个单因素试验,以废纸纤维和淀粉类胶黏剂为主要原料,将2种不同种类的发泡剂以3种组合方式施加到混合物中,采用微波发泡的方法制备了纸纤维发泡材料。通过测定样品成型后的密度、发泡倍率、发泡失重率和干燥失重率,比较了3种不同的发泡剂配方对样品性能及制备过程的影响程度。结果表明:利用各种发泡剂分解温度相异的特点将发泡剂复配,使纸纤维材料在加热过程中分段发泡,具有较好的发泡效果,而且后期干燥的能耗也少。     

Competitive adsorption of surfactant foaming agents to nanoclays added to cement foams for enhanced strength

The adsorption affinity of a surfactant foaming agent (SFA), α-olefin sulphonate (AOS)—used for generation of foam for low density concrete—to organically-modified montmorillonite (OMMT) has been investigated. OMMT has been proposed as an additive to cement and concrete for improved strength and durability. Similar thermodynamic processes are involved in the generation and stabilisation of foam and in the compatibilisation and stabilisation of organic particles in aqueous environments, so interaction between SFA and OMMT particles is likely. Association of foaming agent molecules with organoclay may lead to poor foaming performance and potential instability of the nanoparticles due to displacement of dispersants from the particle surface by foaming agent. Adsorption isotherms determined using a combination of ion-pair reverse phase high performance liquid chromatography (RP-HPLC) and gravimetric methods revealed that there is a relatively high affinity of AOS for the organoclay particles. This is a dynamic process, with smaller molecules adsorbing quickly but being displaced by larger molecules at higher surfactant loading. From the adsorption isotherm it was possible to calculate the minimum AOS addition that will ensure the full foaming performance in the cement formulation. Relative adsorption affinity and competitive adsorption at the particle surface of AOS with non-ionic and anionic surfactants commonly used as wetting and dispersing agents, was studied. The dispersants displayed considerably higher relative adsorption onto the organoclay than AOS, particularly in the case of the anionic species. There is evidence that some AOS adsorption takes place in particle systems stabilised by non-ionic dispersants; displacement of high adsorption affinity dispersants by the lower affinity AOS from the OMMT particle surface was not observed.     

双马来酰亚胺泡沫的微观形貌与结构控制研究

以偶氮二甲酰胺(AC)为发泡剂制备了改性双马来酰亚胺(BMI)泡沫,用扫描电镜(SEM)对泡沫的微观形貌进行观察,研究泡沫的发泡过程及不同条件下泡沫的泡孔结构,包括密度、孔径、单位体积的泡孔数目、发泡倍率等。结果表明:改性的BMI泡沫是一种闭孔结构泡沫,其构型为排泄型十二面体。可通过发泡体系的黏度、温度和发泡剂含量控制BMI泡沫的结构,随发泡体系黏度的增加,泡沫密度,成核密度N0和单位体积的泡孔数目Nf增加,泡孔直径减小,均匀性变好。泡沫密度随发泡剂AC含量提高而降低,当AC含量超过7%(质量分数)时,泡沫密度反而上升。随发泡温度提高,泡沫密度降低,孔径增大,泡沫成型稳定性变差。     

改性偶氮二甲酰胺/水复合发泡在硬质聚氨酯发泡中的应用研究

目的 通过偶氮二甲酰胺(AC)热分解反应释放出发泡用气体,用改性偶氮二甲酰胺/水复合发泡制备无卤素硬质聚氨酯泡沫(RPUF)。探讨改性偶氮二甲酰胺在聚氨酯发泡中的可行性。方法 通过改变体系中改性偶氮二甲酰胺的用量,探讨改性偶氮二甲酰胺对聚醚发泡体系黏度、聚氨酯泡沫力学性能和导热系数的影响。结果 发泡剂的加入能显著降低聚醚体系的黏度,提高发泡物料的流动性,随着改性AC用量的增加,体系黏度逐渐增加,当改性AC的添加量为0.3 g时,体系黏度最低为2 080 mPa.s。当改性AC用量为0.75 g时,聚氨酯泡沫的表观密度为78.65 kg/m³,压缩强度为539.35 kPa,改性AC的加入使得聚氨酯泡沫的导热系数增高,导热系数为0.023 51 W/mK。结论 改性AC的加入能显著提高硬质聚氨酯泡沫的压缩强度,相比纯水发泡,二者复合发泡性能更优异,可以作为无卤素发泡剂应用于聚氨酯发泡。     

生物质全降解材料微观组织结构与性能关系研究

以采用植物纤维(稻草纤维)、淀粉为主料,通过发泡成型工艺制成的生物质全降解材料为研究对象,研究了该材料在成型过程中气泡孔的生长机理,并采用扫描电子显微镜微区化学分析技术对4种植物纤维、淀粉、发泡剂不同含量的生物质全降解材料微观组织结构进行实验研究。结果表明生物质全降解材料中的植物纤维的连接形式是相互交叉的立体网状结构;发泡剂含量为1.0%时,生物质全降解材料形成的气泡孔为封闭结构且分布比较均匀,这种均匀的结构保证了材料良好的抗冲击性、反弹性和隔热保温性。     

镁合金表面TaC/TaC-Mg/Mg梯度涂层的 残余热应力分析

采用间歇式挤出发泡工艺制备淀粉/PVA复合发泡材料。在淀粉含量固定、甘油作为增塑剂的情况下,研究偶氮二甲酰胺（AC发泡剂）与聚乙烯醇（PVA）的含量对发泡材料的表观密度、发泡倍率、相对硬度、吸水性能、回弹性能以及压缩性能等的影响。结果表明：随着PVA含量的升高,复合材料的表观密度和压缩模量减小,回弹性能变好。PVA含量对吸水率影响不明显,吸水率稳定在20%左右。吸水至饱和状态后,相对硬度随着PVA含量的增加而不断增加。随AC发泡剂含量的升高,复合材料的表观密度减小,相对硬度降低,发泡倍率和回弹率增加,材料的泡孔孔径逐渐增大但是发泡孔径的均匀性变差。当PVA、AC发泡剂的添加质量分数分别为30%, 1%时,复合材料性能最优。     

药用植物剩余物发泡缓冲包装材料的制备及性能研究

以药用植物剩余物纤维为主要原料,淀粉 / PVA 胶黏剂为基体,添加一定量发泡剂及相关助剂,在密闭模具内热压成形了发泡缓冲包装材料。 通过实验与分析,确定了制备材料的工艺与实验条件,研究了药用植物纤维粒度、发泡剂用量、发泡温度及淀粉 / PVA 配比对材料性能的影响。     

高温高盐油藏常用起泡剂研究进展

泡沫流体以其低密度、高粘度和独特的流变性在油田开采中被广泛应用,然而形成泡沫的必要组分是起泡剂,其最重要的性能就是起泡性能和稳泡性能。但在国内一些高温、高盐油藏中,地下泡沫的起泡性能和稳泡性能与室内实验相比均有所下降,未能达到预期的原油采收率。论述了高温、高盐条件下导致泡沫消泡的微观机理;介绍了目前高温、高盐油藏常用的单组分起泡剂、复合/复配型起泡剂的基本类型和苛刻的储层条件对不同类型起泡剂泡沫性能的制约性;同时综述了国内外高温、高盐油藏常用起泡剂的研究进展及油田应用现状;以分子结构、有效官能团、复配微观规律和绿色环保为主要研究方向,展望了我国高温、高盐油藏起泡剂研究发展趋势。     

Process Stability in Serial Production of Aluminium Foam Panels and 3D Parts

Powder Metallurgy (PM) technology is emerging as one of the most promising techniques for the manufacture of net shape components and panels of aluminium foam. Control of the stability of the aluminium foaming process is one of the key issues in a serial production. Since there are many different parameters to be controlled in the raw material, the precursor and the finished foam part, the best solution is to keep all these factors in one centre of competence to exclude external influences and transporting problems. The latest material for the foaming tools plays also a decisive role concerning a high surface quality and a constant heat generation within the foam. New developments such as a precursor testing equipment or a foaming optimized furnace construction guarantees constant production conditions to be equipped for a more and more demanding market.     

交联聚氯乙烯泡沫塑料泡体生长的可视化研究

通过水煮发泡制备了交联聚氯乙烯泡沫塑料,讨论了泡沫塑料泡孔结构随着水煮时间的变化,研究了卸模温度、发泡剂以及成核剂对模压块及泡沫塑料泡孔尺寸的影响,通过光学体视显微镜(OM)和电子扫描显微镜(SEM)观察了泡沫塑料的宏观和微观结构,通过热机械分析仪(TMA)分析了模压块的玻璃化转变温度。结果表明,模压块中含有大量圆球形气泡核,水煮后气泡生长并相互挤压形成具有多边形结构的泡体,得到的泡沫塑料具有闭孔结构;模压块的玻璃化转变温度约为51.4℃,模压后适宜的卸模温度为35～50℃;发泡剂偶氮二异丁腈(AIBN)与偶氮二甲酰胺(AC)用量为1.5∶1(质量比)时制备的模压块中气泡核较小且分布均匀;发泡剂AC还兼具成核剂的作用,体系中无需额外添加成核剂。     

杂交狼尾草发泡缓冲材料的制备及性能研究

为了拓展杂交狼尾草作为植物基发泡缓冲材料在包装领域的市场,减少发泡聚苯乙烯材料对环境的污染,以杂交狼尾草为主要材料,玉米淀粉为胶粘剂,异氰酸酯为发泡剂制备缓冲材料。正交试验结果表明,发泡成型的优化条件为:主料狼尾草与胶粘剂玉米淀粉、聚乙烯醇的质量比为1∶0.3∶0.15;每100 g狼尾草内添加30 mL发泡剂异氰酸酯;微波发泡时间为7 min。狼尾草发泡成型材料在含水率为14.4%时,其密度为0.30g/cm3,每平方厘米的泡孔数为19.7;狼尾草发泡成型材料在应变为15%时,其应力值为76.3 MPa,回弹率为80.99%。研究表明,狼尾草发泡成型材料为偏硬性缓冲材料,适合包装质量大、体积大的产品。     

硬质聚氯乙烯用复合发泡剂的研究

采用活化剂(尿素、碳酸锌)和碳酸氢钠对偶氮二甲酰胺(AC)改性制备硬质聚氯乙烯(R-PVC)用复合发泡剂,并用热分析和放气量检测对复合发泡剂进行了表征。结果表明当AC、NaHCO3、尿素和碳酸锌的质量比为10:10:2.5:2.5时所得的复合发泡剂分解温度处于R-PVC成型加工范围内,吸-放热基本平衡,放气量大且无突发性。采用这种复合发泡剂制备的硬质聚氯乙烯发泡材料具有较好的力学性能和微孔结构。     

泡沫SiC颗粒增强铝基复合材料的制备工艺和拉伸强度

介绍了一种新的泡沫金属材料－泡沫SiC颗粒增强铝基复合,泡沫的孔隙率为60％－85％。用TiH2作发泡剂,采用直接发泡工艺制备。由于复合材料熔体自身粘度较大,不需要采用任何增粘措施,发泡工艺简单,易于操作,该泡沫材料比普通泡沫铝或铝合金具有更高的抗拉、抗压强度。