Matrix-Material Fabrication Technique and Thermogravimetric Analysis of Banana Fiber Reinforced Polypropylene Composites

From the environmental consideration,it would be very interesting to use natural fibers such as banana,jute or coir as reinforcement materials instead of artificial fibers or any kind of synthetic materials.Natural fibers have many advantages over synthetic ones.Polypropylene banana fiber composites(PPBC)are prepared using untreated and alkali-treated banana fibers at 10-25%by weight of the fiber loading.The thermal properties of polypropylene natural fiber composites are very important for technological uses.Thermogravimetric measurements show that the incorporation of banana fiber into PP enhances the thermal stability of composites containing treated fibers,in comparison with untreated fibers.A composite of biodegradable polypropylene(PP)reinforced with short banana natural fibers was prepared by melt blending followed by a hot press molding system.The thermal properties of matrix materials were studied using thermogravimetric analyzers TGA units.It is observed that the introduction of short banana fibers slightly improved the thermo oxidative stability of PP-banana composites.Physical and chemical changes occurred through dehydration,phase transition,molecular orientation,crystallinity disruption,oxidation and decomposition,and incorporation of several functional groups.Systematic investigations of the thermal behavior of polymers in gas,vacuum or inert atmosphere give the knowledge of how change takes place in polymers.To understand such changes thermogravimetric analysis(TGA)and thermal analysis(TG)were performed.It is observed reinforcement of short banana fiber leads to little improvement in the thermooxidative stability of PPBC.Due to the enhancement of thermo-mechanical properties,such composites may be used as building materials namely roof materials,selling materials and many other engineering applications.

基于稀土掺杂上转换纳米材料NaYF_(4):Yb,Er@TGA直接对金属离子进行定量分析的方法探究

目的:基于荧光猝灭或增强机制,构建稀土掺杂上转换纳米材料NaYF_(4):Yb,Er@TGA直接对金属离子进行定量分析的方法,实现对金属离子快速、准确、灵敏检测。方法:通过溶剂热法制备出性能优良的稀土掺杂上转换纳米材料NaYF_(4):Yb,Er@TGA,并对其进行表征;通过测量14种常见的金属离子对NaYF_(4):Yb,Er@TGA荧光强度的影响,筛选能够引起NaYF_(4):Yb,Er@TGA荧光强度增强或下降,且与金属离子浓度呈线性关系的金属离子类型,进而建立检测新方法。结果:金属离子Mg^(2+)、Fe^(3+)分别在浓度范围为0~7.00μg/mL、0~6.00μg/mL与NaYF_(4):Yb,Er@TGA的荧光强度呈现良好的线性关系,其标准曲线方程的线性系数分别为0.9924、0.9982,检出限分别为1.79μg/mL、1.30μg/mL,加标回收率分别为95.5%~98.8%、92.5%~97.8%,方法相对标准偏差分别为4.05%、8.18%。结论:该方法检测限低、准确度较高、精密度较好,有望用于实际样品中Mg^(2+)、Fe^(3+)定量分析。

基于TGA-GC/MS结合化学计量学在食醋品牌鉴别中的应用

该文采用热重分析(thermogravimetry analysis,TGA)-气相色谱质谱联用(gas chromatography/mass spectrometry,GC/MS)技术结合化学计量学分析软件,建立了各品牌食醋的线性判别分析(linear discriminant analysis,LDA)模型。研究建立了TGA-GC/MS联机实验方法,采集5个品牌共103组食醋样本的TGA和GC/MS数据,形成了TGA-GC/MS多谱特征值组合,后经T-test处理、主成分分析(principal component analysis,PCA)及PCA特征提取,选择LDA模型进行建模分析。结果显示,该模型5个单一品牌和其他品牌之间区分正确识别率为:东湖87.63%、恒顺80.41%、宁化府96.91%、紫林80.41%、金山寺87.63%,5个品牌相互之间区分正确识别率为80.00%,聚类分堆和区分效果良好,各品牌食醋正确识别率较高,在食醋品牌鉴别中具有良好的应用前景。

Thermogravimetric Analysis of Swine Manure Solids Obtained from Farrowing, and Growing-Finishing Farms

The modern trend of increasing the number of pigs at production sites led to a noticeable surplus of manure. Separation of manure solids provides an avenue of their utility via thermochemical conversion techniques. Therefore, the goal of this paper was to assess the physical and thermal properties of solid separated swine manure obtained from two different farms, i.e., farrowing, and growing-finishing, and to determine their pyrolysis kinetic parameters. Swine manure solids were dried and milled prior to assessing their properties. Differential and integral isoconversional methods (Friedman, and Flynn-Wall-Ozawa) were used to determine the apparent activation energy as a function of the conversion ratio. Significant differences were observed in the proximate, ultimate composition between both manure types. The higher heating value (HHV) for the manure solids from farrowing, and growing-finishing farms reached 16.6 MJ/kg and 19.4 MJ/kg, respectively. The apparent activation energy computed using Friedman and FWO methods increased with the increase in the degree of conversion. Between 10% and 40% degrees of conversion, the average activation energies, using Friedman method, were103 and 116 kJ/mol for the farrowing and growing-finishing manure solids, respectively. On the other hand, the same activation energies, calculated from FWO method, were 98 and 104 kJ/mol, for solid manure obtained from farrowing and growing-finishing farms, respectively. The findings in this study will assist in the effort to optimize thermochemical conversion processes to accommodate swine waste. This could, in turn, minimize swine production impacts on the surrounding ecologies and provide sustainable energy and biochar streams.

Evaluation of reliability of Coats-Redfern method for kinetic analysis of non-isothermal TGA

A critical examination was made on the reliability of kinetic parameters of nonisothermal thermoanalytical rate measurement by the widely applied Coats-Redfern(CR)equation.For this purpose,simulated TGA curves were made for reactions with different kinetic models,including chemical,diffusion(Janders)and mixed mechanism at different heating rates.The results show that,for reactions controlled kinetically by one mechanism,all solid state reaction models show linear trends by use of CR method and this method can not distinct the correct reaction model.For reactions with mixed mechanism,the CR method shows nonlinear trends and the reaction models and kinetic parameters can not be extracted from CR curves.The overall conclusion from this comparative appraisal of the characteristics of the CR approach to kinetic analysis of TGA data is that the CR approach is generally unsuitable for determination of kinetic parameters.

FTIR and Thermogravimetric Analysis of Three Kinds of Nutshells

The main components and pyrolysis characteristics of Camellia oleifera Abel hells, Castanea mollissima Blume shells, and Castanea mollissima Blume shells were analyzed by using FTIR and thermogravimetric methods. The experimental results indicated that the main components of the three kinds of raw materials consisted of cellulose, hemicellulose, and lignin. The highest contents of hemicellulose, cellulose, and lignin were in Camellia oleiferaAbel shells (49.34% ± 0.07%), Castanea mollissima Blume shells (27.34% ± 0.01%), and Carya cathayensis Sarg shells (49.78% ± 0.01%), respectively. The pyrolysis processes of three kinds of shells generally included three stages, namely dehydration, pyrolysis, and carbonization. The peak values and the appearance times of their pyrolysis rates were closely related to their compositions.

Pyrolysis and combustion kinetics of lycopodium particles in thermogravimetric analysis

Biomass is a kind of renewable energy which is used increasingly in different types of combustion systems or in the production of fuels like bio-oil. Lycopodium is a cellulosic particle, with good combustion properties, of which microscopic images show that these particles have spherical shapes with identical diameters of 31 μm. The measured density of these particles is 1.0779 g/cm2. Lycopodium particles contain 64.06% carbon, 25.56% oxygen, 8.55% hydrogen and 1.83% nitrogen, and no sulfur. Thermogravimetric analysis in the nitrogen environment indicates that the maximum of particle mass reduction occurs in the temperature range of 250-550 °C where the maximum mass reduction in the DTG diagrams also occurs in. In the oxygen environment, an additional peak can also be observed in the temperature range of 500-600 °C, which points to solid phase combustion and ignition temperature of lycopodium particles. The kinetics of reactions is determined by curve fitting and minimization of error.

基于TGA和Py-GC/MS不同成熟度煤的热解特征研究

采用热重分析(TGA)和热解–气相色谱/质谱(Py-GC/MS)联用技术对6个不同成熟度煤的热解过程及热解产物进行表征。TGA结果表明,不同成熟度煤的失重(TG)曲线具有相似性且在失重速率(DTG)曲线中有3个明显的失重速率峰;随着成熟度的增加,煤在最高热解温度时的总失重率(wt)减小,最大失重速率(−(dw/dt)max)降低,但最大失重速率峰温度(Tmax)升高,说明低成熟度煤中热不稳定结构的含量较高。Py-GC/MS结果表明,不同成熟度煤的热解产物均以芳香类化合物为主(47.4%~94.7%),且芳香类热解产物的含量随成熟度的增加逐渐升高,说明高成熟度煤热解过程中产生的芳香类化合物较多,而热解产物中酚类、呋喃类和脂肪烃类化合物的占比随煤样成熟度的增加逐渐降低,表明低成熟度煤在热解过程中释放出高含量的极性含氧化合物。研究结果对进一步了解煤炭资源的规模化开发和合理利用具有重要意义。

Evaluation of oxygen uncoupling characteristics of oxygen carrier using micro-fluidized bed thermogravimetric analysis

Oxygen uncoupling characteristics of a natural manganese ore and a perovskitetype oxide CaMn_(0.5)Ti0_(37)5Fe_(0.125)O_(3)were studied by using a microfluidized bed thermogravimetric analysis(MFBTGA)technology which is based on a realtime mass measurement of fluidizing particles inside a bubbling bed reactor.The chemical stability,kinetics of the oxygen release and uptake reactions and fluidization property were investigated and the experimental data measured by MFBTGA were compared with the results in a regular TGA instrument(TGA Q500).The regular TGA Q500 results show the reactivity of both the manganese ore and perovskite oxide are stable for multi cycles,and the oxygen uncoupling capacity of the manganese ore is~1.2%(mass)which is~2 times higher than that of the perovskite oxide.However,the experimental results from the MFBTGA indicated that there is a serious agglomeration for the manganese ore.A very important finding is that the reaction rate of oxygen release and oxygen uptake of the perovskite oxide measured by the MFBTGA are~2 and~4 times faster than that of testedby the TGA Q500.We can conclude that MFBTGA is a very useful tool to measure the reactivity stability and kinetics of oxygen carriers in highthroughput analysis instead of the regular TGA.

玉米TGA转录因子家族全基因组鉴定及盐胁迫相关表达分析

[目的]TGA基因家族是玉米中的一类转录因子,是植物生长发育、响应生物胁迫和非生物胁迫的关键调控因子。玉米是我国重要粮食作物,其胁迫响应分子机制的研究对于玉米生产具有重要理论意义。[方法]利用生物信息学方法对玉米TGA基因家族的理化性质、亚细胞定位、进化关系、染色体定位与共线性、基因结构和基因表达进行分析。利用高通量转录组数据,明确各基因在玉米不同组织、不同发育时期的表达水平以及盐胁迫条件下的响应,利用qRT-PCR对盐胁迫响应的TGA基因进行表达验证。[结果]通过同源比对在玉米全基因组中共筛选到21个TGAs同源序列,都包含bZIP结构域和DOG1结构域,蛋白定位的预测均定位于细胞核。进化分析显示ZmTGA家族基因可划分为5个群组。共线性分析显示ZmTGA家族成员中有7对基因在进化过程中存在共线性关系,玉米ZmTGA家族与单子叶植物(水稻)TGA基因组成共线性基因数量大于其与双子叶植物(大豆和拟南芥)对比的数量。转录组数据分析结果显示,ZmTGAs在不同组织中表达模式不同,ZmTGAs家族基因普遍在根中表达。基因表达分析显示ZmTGA7和ZmTGA11受盐胁迫诱导表达。[结论]利用生物信息学等方法在玉米全基因组中共筛选到21个ZmTGA同源序列,并分析了基因、蛋白结构及理化性质等。共线性分析也发现7对基因在进化过程中存在共线性关系。组织特异性表达分析表明在不同组织中表达模式不同,暗示ZmTGAs在玉米生长发育过程中对不同组织起调控作用。盐胁迫转录组及表达水平分析结果显示ZmTGA7和ZmTGA11其表达受高盐胁迫诱导,可能参与玉米盐胁迫响应调控。

Use of Thermogravimetric Analysis for Moisture Determination in Difficult Lyophilized Biological Samples

Residual moisture is a key quality control parameter for lyophilized biologicals, as high moisture can correlate with poor stability. Coulometric Karl Fischer titration is the most widely used technology to determine residual water content;some chemicals are known to cause problems with Karl Fischer titration, but these chemicals do not usually occur in biologics. Three biological samples, of fibrinogen, heparin and Haemophilus influenza b polysaccharide, have caused particular issue in our hands by routine Karl Fischer analysis, illustrating different limitations with this method. The use of thermogravimetric analysis, with evolved gas mass spectrometric monitoring, is described here as a successful alternative for moisture analysis in these materials.

Characterization by Thermogravimetric Analysis of Polymeric Concrete with High Density Polyethylene Mechanically Recycled

This paper presents the results of the characterization by thermogravimetric analysis of a new composite material called polymeric concrete. The polymeric concrete contains micro-particles obtained from High Density Poly-Ethylene (HDPE) mechanically recycled (post-consumer bottles);the official Mexican standard NMX-E-232-SCFI-1999 considers the HDPE as the recyclable plastic material. Thermo-grams based on weight lost were obtained from the raw material (HDPE) and the polymer concrete in order to obtain the glass transition temperature (Tg) and melting temperature (Tf). The analysis conditions were defined from 20°C to 180°C and the heat rate of 1°C/minute. The results show that the glass transition temperature of polymeric concrete is 46°C and the HDPE is 38°C. These results mean that the polymeric concrete is more resistant to decomposition. With respect to the melting temperature, the results show that the 2°C difference between polymeric concrete and HDPE is not significant. The polymeric concrete with HDPE recycled can be considered as composite material thermoplastic. The new material melts when it is heated to 146°C and has the ability to be softened, processed and reprocessed with temperature and pressure changes, which make it possible to obtain molded pieces in the desired shape.

鲍鱼脏器碱提多糖的分离纯化、结构表征及抗氧化活性研究

目的:分离纯化鲍鱼脏器碱提多糖(alkali-extracted abalone vscera polysaccharides,Aavp),并研究其结构和抗氧化活性,以期为鲍鱼脏器碱提多糖的开发及应用提供参考。方法:通过热碱提醇沉获得鲍鱼脏器碱提粗多糖,经DEAE Sepharose Fast Flow和Sephacryl S-400 HR纯化得到高纯度多糖,并利用气相色谱、高效液相色谱、红外光谱和热重分析仪等工具分析其结构及抗氧化活性。结果:粗多糖纯化后得到四个组分,包括Aavp Ia、Aavp Ib、Aavp IIa和Aavp IIb,其中Aavp IIa得率较高,选择其进一步进行结构分析。分析发现,Aavp IIa由木糖和半乳糖组成,分子量为166513 Da;糖苷键构型为α型,组成如下:半乳糖1→4糖苷键摩尔百分比为11.81%,半乳糖1→3糖苷键为34.14%,半乳糖1→2糖苷键为10.14%;木糖1→3糖苷键摩尔百分比为33.85%,1→2和1→4糖苷键共占10.06%。热重分析显示,Aavp IIa在226.4-332.6℃下断裂分解,热失重率为43.65%。抗氧化实验显示Aavp IIa对O2-·的清除率为85.89%,对DPPH·的清除率为62.17%,具有一定的抗氧化活性。结论:提取的鲍鱼脏器碱提多糖是一类杂多糖,并具有一定的抗氧化活性。

硼砂煅制工艺优化及质量评价

目的 优化硼砂煅制工艺,并对其进行质量评价。方法 以铺设厚度、煅制温度、煅制时间为影响因素,失水率、蓬松度、粉碎率、四硼酸钠含量为评价指标,星点设计-效应面法优化硼砂煅制工艺。采用扫描电镜(SEM)、热重分析(TG)、拉曼光谱、X射线衍射(XRD),比较硼砂煅制前后质量差异。结果 最佳条件为铺设厚度2 cm,煅制温度365℃,煅制时间100 min。煅制后,硼砂微观形态、成分组成、晶型结构发生变化,失去全部结晶水而转变为非晶体状态。结论 该方法稳定可行,可用于工业大批量生产煅硼砂。

咖啡渣和去油咖啡渣热解特性的试验研究

【目的】研究咖啡渣(spent coffee grounds,SCG)和去油咖啡渣(defatted coffee grounds,DCG)的热解特性并计算其热解动力学参数,分析两者在不同温度下热解三相产物的变化规律,实现废弃咖啡渣的二次利用。【方法】采用管式炉、热重(thermogravimetry,TG)试验和热裂解-气相色谱-质谱联用仪(pyrolysis-gas chromatography mass spectrometer,Py-GC-MS)开展了热解产物分布和热解特性的研究,采用Flynn-WallOzawa(FWO)法计算了热解动力学参数。【结果】热重分析结果表明,SCG和DCG热解可分为4个阶段,主要热解温度范围为200~400℃,并且在300℃左右时失重率最大,升温速率可促进热解反应的进行。动力学计算结果表明,当转化率由0.1提高至0.7时,SCG和DCG的活化能均随之不断升高,转化率由0.7提高至0.9时,两者活化能均随之有所下降;SCG和DCG的平均活化能分别为293.58和307.86 kJ/mol。Py-GC-MS分析表明,SCG主要热解产物包括芳香族、酚类、醛类等化合物,DCG主要热解产物包括醛类、酚类、杂环类、酯类等化合物,在热解阶段,随着热解温度的升高,芳香族、酚类、杂环类化合物相对含量减少,醛类化合物相对含量先增加后减少。管式炉热解试验结果表明,SCG的热解产物中生物油产率较高,DCG的热解产物中焦炭产率较高。【结论】SCG和DCG在合适的温度下进行热解,有利于酚类、芳香族化合物等重要工业原料的回收,实现其高值化利用。

飞机客舱饰面型防火涂料的防火阻燃性能研究

为研究飞机客舱饰面型无机复合膨胀型阻燃体系,首先提出并制备了三种不同配比的防火涂料,接着对涂料的干燥时间、涂层厚度及涂层黏度进行了测试分析,然后对其进行了模拟大板实验,得出并分析了三种试样的升温速率曲线,分析了燃烧后的炭层,最后通过热重分析(TG)、差热分析(DTA)两种热分析手段对三种试样进行了热特性分析,得出试样2的防火阻燃效果最佳。结果表明:季戊四醇、聚磷酸铵、三聚氰胺三者协同作用,在火场中不仅可产生难燃气体,起到气相阻燃作用,同时可分解产生无机物,从而在可燃物表面形成一层致密的氧化物薄膜,使新型涂料具有良好的防火阻燃效果;当苯丙乳液、硅溶胶、聚磷酸铵、三聚氰胺、季戊四醇、氯化石蜡、二氧化钛的质量配比为380∶95∶336∶183∶56∶46∶69时,涂料的防火阻燃性能最佳。

西藏三种木材生物质的燃烧特性及动力学分析

为了探讨西藏地区丰富的藏川杨、高山松和川滇高山栎3种木材生物质在燃烧过程中的反应机理,采用热重分析了三种木材的燃烧特性,通过Coats-Redfern积分法研究了其动力学特性。结果表明:3种木材生物质燃烧过程总体趋势一致,可分为失水干燥、生物质燃烧、焦炭燃烧和生物质燃尽共4个阶段,其中挥发分燃烧阶段失重占比最大。根据综合燃烧特性指数,川滇高山栎的燃烧特性最好,其次是藏川杨、高山松;随着升温速率增大,木材生物质的综合燃烧特性指数增大,燃烧速率增大,DTG曲线峰值增大,峰形变宽;藏川杨、高山松和川滇高山栎的最佳反应级数分别为1、2、2,相关系数均大于0.95。燃烧反应活化能从低到高分别为:藏川杨46.10 kJ/mol、高山松70.05 kJ/mol、川滇高山栎85.59 kJ/mol;频率因子从低到高依次为:藏川杨2.25×10^(4)min^(-1)、高山松3.99×10^(6)min^(-1)、川滇高山栎2.14×10^(7)min^(-1),该研究为优化燃烧过程和提高能源利用效率提供了理论依据。

生物质热解的TGA-FTIR分析

基于TGA-FTIR联用技术,在线分析研究稻壳、稻秆及麦秆3种典型生物质在不同升温速率下的热解特性。分析生物质种类及升温速率对生物质的热解动力学参数及热解产物的影响。研究表明:由于生物质组成不同,其热失重特性也不同,生物质热解反应的活化能较低,为40～60 kJ·mol^(-1);红外分析表明试验用生物质热解过程中产物的析出规律相似,热解初始阶段先析出游离水,随后发生解聚和脱水反应,生成各种烃类、醇类、醛类和酸类等物质。随后,这些大分子物质又二次降解为一氧化碳为主的气体产物。

应用TGA-FTIR研究不同来源污泥的燃烧和热解特性

在空气气氛下，利用热重分析方法研究了三种不同来源的污泥燃烧特性。探讨水处理工艺和污泥处理工艺对污泥中有机物的分布影响和燃烧特性影响。研究发现，污水厌氧工艺和污泥厌氧工艺均导致结构复杂、燃烧温度高的有机物生成。在氮气气氛下利用热重红外联用技术，对比研究了同种污泥的热解和燃烧特性，污泥热解主要发生有机物裂解成小分子和小分子的挥发，氧气的存在加速了污泥的裂解。污泥热解温度200℃～500℃，主要气体H2O、CO2、CO以及甲烷等烃类，CO2在高温750℃还存在一个析出峰，由于无机碳酸盐的分解。

钙基固硫剂高温固硫反应特性的TGA试验研究

燃煤固硫过程中,要求固硫剂具有良好的高温固硫性能。该文通过热重分析方法对钙基固硫剂的固硫反应特性进行了试验研究,其中着重研究了固硫剂的种类、添加剂含量及反应温度对固硫剂钙利用率的影响。结果发现人工配制的复合钙基固硫剂及新型的天然固硫剂-贝壳具有较好的高温固硫性能,与纯CaO相比,其最佳固硫温度向高温区移动约100℃。在1180℃下,添加剂的加入可使固硫剂的钙利用率提高15个百分点。所得试验结果为燃烧中固硫剂的选择并提高其利用率提供了依据。