Design of Porous Banana Foam Mat to Resist Moisture Migration Using a 2-D Stochastic Pore Network and Its Textural Property

The high porosity of dried banana foam allows it to quickly adsorb moisture from the air during storage, leading to a loss of quality and textural properties. Therefore, the main purpose of this research was to design and study banana foam structure at the pore level to limit moisture migration using a 2-D stochastic pore network. A 2-D network formed by the interconnection of cylindrical pores was used to represent the voids inside the banana foam and the moisture movement inside the individual pore segments during adsorption was described by Fick's law. The pore network was divided into two layers with different banana foam densities and the top surface of the network was exposed to humid air. The upper layer was assigned with pore sizes from the banana foam density of 0.31 g/cm³, having a void area fraction of 0.22, or from a density of 0.21 g/cm³, having a void area fraction of 0.31; the lower layer was assigned specifically with the pore sizes from the banana foam density of 0.26 g/cm³, having a void area fraction of 0.26. The predictions agreed well with the experimental results, with an R² value above 0.95. The two-layered banana foam mat with high banana foam density (characterized by mostly small pores) on the upper layer could limit the transport of moisture, with a rate relatively lower than that of a single-layered banana foam mat, and also exhibited more crispiness than the single banana foam. However, when the low banana density was in the upper layer, the two-layered sample adsorbed moisture quickly and its texture was less crispy.     

Influences of Pretreatments and Drying Process Including Fluidized Bed Puffing on Quality Attributes and Microstructural Changes of Banana Slices

Healthy snacks have received more attention because of their low fat content. Color and texture are important to snack quality. Effects of chemical pretreatment, thickness, blanching, and puffing temperature on quality of banana slices were therefore investigated. Banana slices (2.5 and 3.5 mm thickness) were chemically treated by citric acid and sodium metabisulfite, blanched, and dried at a temperature of 90°C to an intermediate moisture content of 25% db. They were then puffed in a fluidized bed dryer at 160 and 180°C for 2 min and dried again at the same drying temperature as the first drying step. Blanching, puffing temperature, and thickness strongly affected the degree of shrinkage, effective moisture diffusivity, morphology, textural properties such as hardness and crispiness, and color, but the chemical treatment did not affect those qualities. Blanching can improve the product appearance; the color was uniform and shiny throughout the surface and golden yellow. However, the textural attributes of the blanched sample had higher hardness and less crispiness than those of unblanched sample.     

改性条件对聚氨酯硬质泡沫冲击性能影响研究

将纳米二氧化硅（SiO2）和玄武岩纤维与聚氨酯复合制备了聚氨酯硬质泡沫材料,研究了异氰酸酯指数,水、纳米SiO2和玄武岩纤维的添加量及玄武岩纤维的长度等因素对其冲击性能的影响。结果表明,当异氰酸酯指数为1.05、纳米SiO2的添加量为3.0 %、5.0 mm玄武岩纤维的添加量为3.0 %时,材料的冲击强度达到最佳值。     

Modeling of Diffusion with Shrinkage and Quality Investigation of Banana Foam Mat Drying

A diffusion model including shrinkage has been developed for predicting the change of moisture content in banana foam mats during drying. Two solution methods, moving boundary using variable grid and immobilizing boundary using the Lagrangian referential coordinate, were used in exploring their capabilities to predict the moisture change. Banana foam mats with initial foam densities of 0.3, 0.5, and 0.7 g/cm³ were dried at 60, 70, and 80°C and superficial air velocity of 0.5 m/s. The qualities of the final products in terms of texture and microstructure were determined. The moving boundary method can predict the moisture content more accurately than the immobilizing boundary method especially in the case of low-density foam. The quality determinations showed that the initial foam density strongly affected hardness, crispness, and morphology of dried banana foam mats, whereas the drying temperature had no significant effect on those qualities.     

Fixed‐Bed Adsorption of Allura Red Dye on Chitosan/Polyurethane Foam

The potential of a chitosan/polyurethane foam (CTS/PU) fixed‐bed column for the removal of Allura Red dye (AR) from aqueous solutions was evaluated. Breakthrough curves were constructed under different conditions and optimized using response surface methodology (RSM). The empirical models Thomas, Yoon‐Nelson, and Bed Depth Service Time (BDST) were fitted to the experimental data. The dynamic models of Yoon‐Nelson and BDST accurately fitted the experimental data. As a result, CTS/PU can be successfully applied in a fixed‐bed adsorption operation to remove AR dye.     

EPR改性PP微穿孔板吸声性能的研究*

用自行研制的 Ｅ Ｐ Ｒ 改性 Ｐ Ｐ基阻燃泡沫材料制成微穿孔板,研究其吸声特性及规律,并与 Ｅ Ｐ Ｒ 改性 Ｐ Ｐ基阻燃非泡沫材料微穿孔板进行对比。结果表明,泡沫材料微穿孔板吸声体在中、低频率区域的最大吸声因数可达０９８ 以上;在１２５ ～２ ０００ Ｈｚ 范围内平均吸声因数可达０５２ 以上。     

泡沫掺量对泡沫混凝土孔结构及铅离子吸附性的影响

以P·O42.5硅酸盐水泥为主要原材料,采用压缩空气发泡方式制备了泡沫混凝土,通过立体显微镜观察并表征不同泡沫掺量下泡沫混凝土孔结构,基于不同孔结构研究了泡沫混凝土对Pb2+的吸附作用.研究结果表明,当泡沫掺量为3.77％～ 5.28％时,随泡沫掺量增加气孔的圆度逐渐增大,平均弦长和气孔间距系数均随泡沫掺量增加而逐渐增大,小于0.2 mm的孔含量逐渐减少,0.2～2 mm的孔含量增加,2～4 mm的孔含量显著增加.泡沫混凝土对Pb2+的吸附在动力学上符合准二级动力学模型,等温吸附符合Langmuir吸附等温式,以化学吸附为主.泡沫混凝土对Pb2+的吸附容量高,吸附速率较快,可广泛应用于含Pb2+废水的处理.     

烷基糖苷的制备与性能

介绍了以对甲基苯磺酸为催化剂 ,以葡萄糖和醇为原料合成APG的方法。确定了较佳工艺条件为 :正丁醇与高碳醇之比为 1∶1(mol/mol) ,醇糖比为 3∶1(mol/mol) ,用H2 O2 脱色 ,反应温度为 110～ 115℃ ,反应时间为 1 5h ,葡萄糖的转化率达到 98% ,合成出的产品性能好 ,特别适用于餐具洗涤剂和洗发香波     

软质聚氨酯泡沫塑料隔热性能研究

研究了软质聚氨酯泡沫塑料隔热性能的影响因素,讨论了泡沫压缩率、泡沫密度、温度及泡沫吸水率与导热系数的关系,结果表明,温度、密度及吸水率是影响泡沫隔热性能的主要因素。     

泡沫对工业发酵的影响及控制

从泡沫的形成和消长规律出发,介绍泡沫对工业发酵的影响和泡沫的控制方法,并提出控制泡沫的措施。     

轻质环氧树脂微孔发泡材料的力学及隔热性能

通过添加不同含量的化学发泡剂,制备了较小密度(0.5 g/cm~3)的环氧树脂基微孔发泡材料,研究了发泡剂含量(0.25%~2%)对环氧复合发泡材料发泡行为的影响,并讨论了材料的力学性能及隔热性能的变化规律。结果表明,随着发泡剂含量的增加,材料的表观密度不断降低,但泡孔尺寸不断增大,泡孔密度则不断降低。力学性能及隔热性能测试表明,随发泡剂含量的增加,材料的压缩屈服强度和压缩弹性模量不断降低,但是材料的隔热性能不断提高。     

就地CO2泡沫体系的静动态吸附特征研究

研究了体系中起泡剂和稳泡剂的吸附量并通过岩心流动实验,测定了起泡剂和稳泡剂在含油、不含油条件下的滞留量。研究结果表明,稳泡剂的吸附等温线呈“L”型,油砂上的饱和吸附量小于石英砂上的饱和吸附量;起泡剂的吸附等温线呈典型的“S”型,油砂表面上的吸附量总是小于在石英砂表面上的吸附量;稳泡剂和起泡剂的动态吸附量都小于在岩心砂上的静态吸附量,化学剂在含油岩心中的滞留量小于不含油岩心中的滞留量。     

磁性石墨烯泡沫的制备及对Cu2 的吸附性能研究 ?

本文以氧化石墨烯为前驱体,采用溶剂热法制备了磁性石墨烯泡沫 (MGF) 复合物。用X-射线衍射(XRD)、透射电镜 (TEM) 及场发射扫描电子显微镜 (FESEM) 等对其进行了表征。在不同的实验参数 (铜离子初始质量浓度、反应时间和温度)下,研究了复合物对水溶液中铜离子的吸附性能。结果表明：Fe3O4成功复合到了石墨烯上且为三维泡沫结构;复合物对铜离子吸附量可达49.20 mg⁄g;吸附过程符合准二级动力学模型。磁性复合物可以借助外部磁场实现快速磁分离。     

匀泡剂对硬质聚氨酯泡沫孔径及冲击性能的影响

通过改变配方中匀泡剂的用量,制备了一系列具有相同密度的硬质聚氨酯泡沫塑料(RPUF)。使用二维图像分析方法对其孔径进行了表征,结果显示其孔径分布在210～624μm范围。研究了冲击性能与孔径之间的关系,发现材料的冲击强度随孔径增大呈线性下降的趋势,同时其脆性增大而韧性降低。     

聚氨酯软泡叔胺催化剂用量及化学动力学研究

通过对软质聚所酯泡沫塑料发泡反应中水与ＴＤＩ反应机理的探讨，运用化学动力学和热力学理论推导出理不同水和物理发泡剂用量时叔胺催化剂用量的计算公式。生产实践表明，计算值与经验值相符，从而证明了公式对生产配方中叔胺催化剂的用量的确定有指导作用。     

Effective Diffusivity and Evaporative Cooling in Convective Drying of Food Material

This article presents mathematical models to simulate coupled heat and mass transfer during convective drying of food materials using three different effective diffusivities: shrinkage dependent, temperature dependent, and the average of those two. Engineering simulation software COMSOL Multiphysics was utilized to simulate the model in 2D and 3D. The simulation results were compared with experimental data. It is found that the temperature-dependent effective diffusivity model predicts the moisture content more accurately at the initial stage of the drying, whereas the shrinkage-dependent effective diffusivity model is better for the final stage of the drying. The model with shrinkage-dependent effective diffusivity shows evaporative cooling phenomena at the initial stage of drying. This phenomenon was investigated and explained. Three-dimensional temperature and moisture profiles show that even when the surface is dry, the inside of the sample may still contain a large amount of moisture. Therefore, the drying process should be dealt with carefully; otherwise, microbial spoilage may start from the center of the dried food. A parametric investigation was conducted after validation of the model.     

Adsorption kinetics of 3-hydroxybenzaldehyde on native and activated bentonite

In this study, the adsorption kinetics of 3-hydroxybenzaldehyde dissolved in ethanol on native and activated (acid/heat activation) bentonites were examined. The specific surface areas, pore size and pore-size distributions of the samples were fully characterized. The cation exchange capacities (CEC) of the native and activated bentonites were found as 65 and 97 meq/100 g, respectively. The adsorption efficiency of 3-hydroxybenzaldehyde onto the native and activated bentonites was increased with increasing initial bentonite amount and temperature. Also, it was found that the adsorption efficiency with activated bentonite was greater than native bentonite. The kinetics of adsorption of 3-hydroxybenzaldehyde was discussed using three kinetic models, the pseudo-first-order, the pseudo-second-order and the intra-particle diffusion model. The experimental data fitted very well the pseudo-second-order kinetic model and also followed the intra-particle diffusion model up to 20 min. The rate constants of pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics and the amount of the solute sorbed at equilibrium were determined. The initial sorption rate and the activation energy were also calculated. The activation energy of the sorption was calculated using the pseudo-second-order rate constant, and it was found to be 53.36 kJ mol^− 1 and 14.03 kJ mol^− 1 for native and activated bentonites, respectively.     

用锥形量热仪研究聚氨酯泡沫的阻燃性能

在50 kW/m2辐射功率下,利用锥形量热仪研究了氢氧化铝、卤系阻燃剂、氮系阻燃剂和磷系阻燃剂阻燃聚氨酯泡沫(PUF)的阻燃特性,获得了点燃时间、最大热释放速率、总热释放、比消光面积及质量损失速度等参数。结果表明,将热释放速率、燃烧总释放热和烟气释放量作为材料阻燃性能好坏的评价指标,阻燃剂聚磷酸铵（APP）和三聚氰胺磷酸盐（MP）是PUF的理想阻燃剂。     

Adsorption of biomolecules on mesostructured cellular foam silica: Effect of acid concentration and aging time in synthesis

Mesostructured cellular foam (MCF) silica was synthesized using a non-ionic surfactant template-directed method without ammonium fluoride; the acid concentration and aging time were varied to determine the effects of these parameters on the final material. Increasing the acid concentration and aging time resulted in larger window size, which is critical in gating of biomolecule access to the interior of the MCF silica. In particular, when the acid concentration was changed from 1.6 to 3.5 M the window pore dimension approximately doubled, although the pore size distribution was broader. In this study, the optimal synthesis conditions to produce large, narrowly distributed window pores are 3.5 M HCl with an aging time of 20 h. The loadings of l-tryptophan (Trp), lysozyme (LYS) and bovine serum albumin (BSA) on the MCF samples were measured using batch adsorption. Adsorption data followed a Type I isotherm. The monolayer adsorption capacity of Trp on acid-washed MCF was several times higher than that of LYS and BSA, because of the smaller size of Trp. Protein adsorption onto MCF silica showed minimal size exclusion until the window size of the silica was barely larger than the largest protein dimension.     

粉体对泡沫灭火剂发泡能力和热稳定性影响研究

研究了纳米二氧化硅、硅微粉、石墨、纳米级铜粉对于蛋白泡沫的发泡能力及热稳定性的影响,并且测试了形成的复合泡沫的热稳定性,结果表明：将耐烧粉体直接添加进灭火泡沫中有望增强其抗烧能力和灭火性能。在常温下纳米二氧化硅以及纳米级铜粉能与蛋白泡沫较好的结合为复合泡沫,添加测试粉体后复合泡沫的热稳定性均有明显增强,其中添加纳米二氧化硅和纳米级铜粉的复合泡沫整体性能良好,无泡沫排液和聚并现象,可以起到良好的隔热作用。