Flammability properties and mechanical performance of epoxy modified phenolic foams

This work has been mainly focused on the development and optimization of the processing methodology to produce epoxy modified phenolic foams. This study analyzes the relation between the composition and the structure as well as the mechanical and flammability performance of epoxy‐phenolic (E‐P)‐based foams. Phenolic foams modified with different types and compositions of epoxy resin were successfully synthesized and characterized, showing uniform pore structure. Two epoxy resins were used for this approach. One is regular diglycidyl ether of bisphenol A (Epon 826) type and the other is a brominated bisphenol A (DER 542), which has halogen groups in the structure to improve the flammability properties of the resulting foams. Cone calorimeter (ASTM E 1354) was used to measure the heat release rate, the time to ignition, and other flammability properties of the E‐P foams with different types of epoxy resins, under well‐controlled combustion conditions. The mechanical performance of the system was studied and compared with competing foams, such us phenolic, epoxy, and polyurethanes, in aspects of compression, friability, and shear performances. Compared with conventional phenolic foams, E‐P foams exhibit significant improvement in mechanical performance, lower friability and similar resistance to flame. These results demonstrate the potential of the E‐P foam as a flame resistant and high performance core material for sandwich structure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1399–1407, 2007     

Flammability and mechanical properties of Al(OH)3 and BaSO4 filled polypropylene

The flammability and mechanical properties of Al(OH)₃/BaSO₄/polypropylene (PP) composites were investigated. The flow, morphological, and thermal properties were also analyzed by melt flow index (MFI), Scanning electron microscopy (SEM), and Differential scanning calorimeter (DSC) studies, respectively. Total filler amount was fixed at 30 wt % to optimize physical characteristics of the composites. In addition to the flame retardant filler Al(OH)₃, BaSO₄ was used to balance the reduction in impact strength at high filler loadings. Substantial improvement in mechanical properties was achieved for 20 wt % Al(OH)₃ (i.e., 10 wt % BaSO₄) composition while maximum flammability resistance was obtained for 30 wt % Al(OH)₃ composite. SEM studies showed that the presence of aggregated Al(OH)₃ particles led to low interfacial adhesion between them and PP matrix ending up with decreased mechanical strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Flammability of polyacrylonitrile and its copolymers II. Thermal behaviour and mechanism of degradation

Homopolymeric polyacrylonitrile and fibre-forming copolymers containing either vinyl acetate or methyl acrylate comonomer have been studied by thermal analysis (DSC, TGA and DTG) at various heating rates (10–100 K min^?1) and under air and nitrogen. Three well-defined pyrolysis stages have been observed which occur over the temperature ranges 250–350°C, 350–550°C and above 550°C. Each stage involves a competition between volatilisation and cyclisation or char-forming reactions which depends on heating rate and the presence or absence of oxygen. The well-established dominance of cyclisation in the 250–350°C temperature range obtained during carbon fibre production from acrylic precursors occurs only at low heating rates. At high heating rates, volatilisation dominates and this explains why acrylic polymers have high flammabilities when heating rapidly. The full pyrolysis mechanism has been semi-quantitatively analysed and the role that comonomers play discussed. This has enabled a fuller understanding of the potential burning behaviour of these polymers to be developed.     

基于微波破壁处理的超声提取桑叶中黄酮的工艺研究

以水为溶剂,超声波提取桑叶中的黄酮,取料液比为1∶8,微波破壁3次,每次30 s,pH为5.5时,超声提取30 m in(功率1 800 W),黄酮的提取率96.9%,得率为874 mg/100 g,纯度达95.13%。微波破壁结合超声提取与传统的煎煮法相比较,具有成本低、产物收率高、可显著降低提取液中杂质含量的优点。     

接骨木多糖的理化性质分析

以接骨木叶为原料,脱脂后,采用水提醇沉法来提取多糖,采用双氧水脱色,木瓜蛋白酶法-三氯乙酸正丁醇联合法进行除蛋白,得到接骨木精多糖。对接骨木多糖的含水量、灰分含量、糖含量、蛋白质含量等理化性质进行分析。结果为:接骨木多糖的蛋白质含量为5.38%,多糖含量为33.62%,水分含量为12.56%,灰分含量为1.7%。     

原位聚合法PS／蒙脱土复合材料燃烧性能的研究

采用原位聚合法分别制备了聚苯乙烯／有机蒙脱土（PS／OMMT）复合材料和聚苯乙烯／无机蒙脱土（PS／MMT）复合材料、用锥形量热仪测量测试了复合材料的燃烧性能，结果发现复合材料的热释放速率、质量损失速率、生烟速率等均显著降低，说明复合材料具有阻燃性。通过分析材料的燃烧性能和燃烧残余物，探讨了其可能的阻燃机理。还考察了原位聚合法对聚合转化率的影响。研究表明原位聚合法制备的PS／蒙脱土复合材料是一种阻燃效能高、环境友好且实际可行的阻燃体系。     

硅烷交联聚乙烯无卤阻燃材料燃烧性能的研究

采用极限氧指数、锥形量热计和热分析等手段，研究了氢氧化镁(MH)和其他类型的无卤阻燃剂在硅烷交联聚乙烯(SXPE)体系中的阻燃协效作用。氧指数实验结果表明，硅烷交联的聚乙烯／氢氧化镁(SXPE／MH)体系的氧指数高于未交联的PE／MH体系的氧指数，若在SXPE／MH阻燃体系中添加适量的其他无卤阻燃剂，如磷氮类化合物(NP-28)和氮类化合物[三聚氰胺氰尿酸盐(MCA)]氧指数都有提高。锥形量热计实验结果表明，在SXPE／MH阻燃体系中添加适量的NP一28或MCA，体系的着火时间有所延长，热释放速率和发烟量也有不同程度的降低。热分析实验结果显示，NP-28或MCA对SXPE／MH体系的热分解特性有一定的影响。     

Study on the Flammability,Crystal Behaviors and Mechanical Performance of Polyamide 11 Composites by Intercalated Layered Double Hydroxides

Sulfamic acid-intercalated MgAl-LDH (SA-LDH) was prepared by an anion exchange method, and its structure was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). SA-LDH was introduced into polyamide 11 (PA11) by melt blending and to enhance the flame retardancy and mechanical properties. The scanning electron microscope (SEM) and XRD data showed that the lamellar structure of SA-LDH was partly disrupted. The cone calorimeter (CCT) results demonstrated that SA-LDH could effectively decrease the value of heat release rate, which may be ascribed to the better distribution of SA-LDH compared to LHD in the PA11 matrix. The effects of SA-LDH on the crystal behaviors of PA11 were investigated by XRD and differential scanning calorimetry (DSC), indicating that SA-LDH could induce the formation of new crystal forms and served as a heterogeneous nucleating agent. The mechanical progress caused by the incorporation of SA-LDH was correlated with compatibility improvement between SA-LDH and PA11.     

熟料物理性能的数值分析

通过建立熟料化学成分与物理性能之间的回归分析,研究了熟料矿物组成和熟料率值等与强度、凝结时间、需水量、强度增长率等物理性能的相关性系数。结果表明,不同的矿物种类对熟料的性能影响不同,单个矿物对熟料某一性能影响较大的,但在与其他矿物相互作用后能够促进或者降低其对性能的相关性系数。这表明熟料矿物之间有很复杂的作用关系,而熟料率值在许多时候对熟料物理性能影响十分有限,因此采用熟料率值控制、监测和预测熟料的物理性能有时是不合适的。     

Probabilistic monitoring of chemical processes using adaptively weighted factor analysis and its application

As a probabilistic statistical method, factor analysis (FA) has recently been introduced into process monitoring for the probabilistic interpretation and performance enhancement of noisy processes. Generally, FA methods employ the first several factors that are regarded as the dominant motivation of the process for process monitoring; however, fault information has no definite mapping relationship to a certain factor, and useful information might be suppressed by useless factors or submerged under retained factors, leading to poor monitoring performance. Weighted FA (WFA) for process monitoring is proposed to solve the problem of useful information being submerged and to improve the monitoring performance of the GT² statistic. The main idea of WFA is firstly building a conventional FA model and then using the change rate of the GT² statistics (RGT²) to evaluate the importance of each factor. The important factors tend to have larger RGT² values, and the larger weighting values are then adaptively assigned to these factors to highlight useful fault information. Case studies on both a numerical process and the Tennessee Eastman process demonstrate the effectiveness of the WFA method. Monitoring results indicate that the performance of the GT² statistic is improved significantly compared with the conventional FA method.     

化学分析分馏过程对生物质焦炭物理化学结构的影响

化学分析分馏过程广泛应用于碱金属及碱土金属对生物质焦炭活性影响的研究。针对化学分析分馏过程对生物质热解焦炭物理化学结构产生的影响展开深入研究。通过压汞仪、扫描电子显微镜(SEM)对化学分析分馏过程中焦炭的孔径分布、孔隙率、比表面积及颗粒表面形貌等物理结构的变化进行了分析,结果表明该过程对焦炭的孔隙率影响显著,对比表面积影响不大,对热解焦炭多孔状表面形貌影响较为突出。利用X射线光电子光谱法(XPS)和拉曼光谱法(Raman)对焦炭表面碳氧活性官能团结构及焦炭芳香环结构等化学结构特征展开了研究,结果表明化学分析分馏过程对生物质焦炭表面碳氧活性官能团结构的破坏作用较小,化学分析分馏对焦炭的芳香环结构影响不大,水洗过程对焦炭内部的交联结构影响不明显,醋酸铵溶液、盐酸对焦炭内部的交联结构破坏明显。     

Flammability and thermal properties of epoxy/glass/MWNT Composites

The aim f this work is to study the effect of nanotubes on flammability properties of epoxy/glass composites. Multiwalled carbon nanotubes (MWNT) and its functionalized derivative (amino functionalized nanotubes) were incorporated into epoxy resin. To disperse MWNTs in the epoxy resin, different ways were employed. Microscopic observations showed that, the best dispersion state was gained by using ultrasonication method and high shear flow simultaneously. Thermal resistance of cured epoxy resins containing various amounts of nanotubes (0.25–0.7 wt %), was investigated by thermo gravimetric analysis (TGA). Introducing MWNTs and amino‐MWNTs to samples increased the initial thermal decomposition temperature for about 32 and 37°C, respectively. LOI measurements of composite samples showed an increase up to 32. Cone calorimetry test was carried out on epoxy/glass and epoxy/glass containing 0.5% MWNT. The results showed that, introducing 0.5% MWNTs decreases maximum average rate of heat emission for about 26%. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39849.     

Evaluation of physical and chemical properties of carrots dried by Refractance Window drying

The Refractance Window? (RW) technique was used to dry carrot slices (3?cm diameter; 0.2 and 0.4 cm thickness) at 74 and 94°C. Moisture loss, texture, color, total polyphenol content (TPC), and antioxidant activity (AA) were evaluated as response variables and were compared with the values of a control (fresh carrot) and the slices dried via convective drying (C) at the same temperatures. The RW method produced a reduction of drying time of 26–51% (p < 0.05) when compared to convective drying. The color, TPC, and AA values for the RW treatment did not differ (p > 0.05) compared with the control. The texture values showed a difference with respect to the control for the two drying methods used. However, between the two drying methods there was no difference in the texture (p > 0.05). The results suggest that the RW technology can be used to develop products with better functional properties compared with those obtained via conventional air-drying methods.     

烷基木糖苷物化性能研究

分别对不同长度碳链和平均聚合度(DP)的烷基木糖苷(AX)进行性能评价,结果表明,AX可将水的表面张力降低到26 mN/m以下,随碳链长度增加,AX临界胶束浓度(cmc)减小,饱和吸附量(Гmax)降低,且Гmax高于相同碳链的烷基葡糖苷(APG),AX的发泡力、泡沫稳定性、抗硬水能力及润湿性能均优于相同碳链的APG。随DP的增大,AX平衡表面张力(γcmc)及cmc均增大,Гmax呈降低趋势,DP对发泡力的影响有限,DP的降低使得AX的抗硬水能力、润湿力和乳化能力有所提高。     

Electrochemical and physical chemical properties of sp carbon microrods

We investigated sp² carbon microrods resulting from the reaction of lithium with hexachlorobenzene. The material exhibits high surface area (200-340 m²/g, depending on heat treatment) and a reversible lithium storage capacity in excess of 500 mA h/g. The discharge/charge behavior of the material resembles that of high specific capacity non-graphitic carbon. Without distinguishable plateaus, the reversible intercalation of lithium occurs at a broad potential window below 1 V vs. Li/Li⁺. A possible mechanism for the rod formation, based on SEM results, is briefly considered.     

Analyses of color emotion for color pairs with independent component analysis and factor analysis

Semantic‐differential data of color emotions for color pairs were collected and examined with factor analysis (FA) and independent component analysis (ICA). The axial orientations of factors cannot be identified by FA, whereas they can be determined by ICA with the intrinsic statistical properties of data such as kurtosis. Three factors or components were extracted by FA and ICA. The factors extracted by FA with the varimax method were consistent with the primary factors: evaluation, activity, and potency. When ICA extracted components with positive kurtosis, the components did not match any of the primary factors. However, the independent components extracted by ICA for negative kurtosis were consistent with the primary factors, and similar to the factors obtained by FA. The results of ICA suggest that the evaluation, activity, and potency factors are independent dimensions in psychological space of color emotions for color pairs. The distributions of the factor scores in FA and the scores of the independent components obtained by ICA for negative kurtosis were not Gaussian, but they had negative kurtosis. These support the use ofICA instead of FA. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 297–308, 2013     

甲醇汽油的理化性能研究

通过对甲醇汽油馏程、蒸汽压、实际胶质、抗相分离性能等关键理化性质的进一步分析,提出了目前调制甲醇汽油所存在的主要技术问题。     

Correlating chemical structure and physical properties of vegetable oil esters

The influence of FA ester chemical structures on the rheology and crystallization temperature of those compounds was evaluated using methyl, n-butyl, n-octyl, and 2-ethyl-1-hexyl FA esters with different chain lengths and different degrees of unsaturation. The rheological properties were analyzed in a high-precision rheometer at various temperatures, and the crystallization temperatures were determined by DSC. Esters produced from the esterification of pure FA and from the transesterification of vegetable oils (i.e., soybean, corn, linseed, and babassu coconut oils) were evaluated. The length of the FA chain was shown to have a marked influence on the viscosity and crystallization temperature of the systems, whereas branching affected only the crystallization temperature to a significant extent. The viscosity and crystallization temperature of the systems were also influenced by the degree of unsaturation. One double bond was shown to increase viscosity, whereas two or three double bonds caused a decrease in the viscosity of the systems. Unsaturation lowered the crystallization temperature in all cases, regardless of the number of double bonds. From all the oils studied, methyl esters from babassu coconut oil presented the lowest crystallization temperatures.     

Optimizing the deformation properties of ceramic pastes by evaluating relevant physical and chemical mechanisms

The peculiarities of the boundary layers in silicate dispersions are described as the factors that control the interactions between the solid particles, and thus determine the structural, mechanical and deformation properties. The importance of surfactants and regularities of the structure formation are also discussed. The usefulness of elastic-plastic-viscous constants for elaboration of the optimized technology in ceramic industry is shown and the preparation of ceramic dispersions (slips) with various contents of solids, plastic pastes, semidry masses, and highly concentrated powders are analyzed.     

近红外光谱技术在中药栀子渗漉液理化指标快速分析中的应用研究

用声光可调滤光器(AOTF)-近红外(NIR)光谱法在线分析栀子渗漉液密度及栀子苷含量。在线收集栀子渗漉液样品,建立栀子渗漉液的含量、比重数据库,同时采集近红外光谱图谱,用偏最小二乘(PLS1)法分别建立NIR光谱与含量、比重数据之间的校正模型,并对在线过程中收集的预测集样品进行含量预测来验证所建模型。结果表明,渗漉液NIR光谱与含量、比重数据之间的校正模型相关系数R2分别为0.956 0和0.978 2,外部样品预测平均相对偏差分别为0.09%,2.84%;该方法精密度RSD分别为0.06%,2.96%;稳定性RSD分别为0.63%,1.89%;预测回收率分别为100.0%,99.9%。近红外光谱技术在栀子渗漉液密度及淫羊藿苷含量分析中具有快速、直接、多成分同时测定,并能实现现场分析。