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.

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.

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 ℃ 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 ℃, 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.

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.

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.

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.

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.

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。

Spontaneous combustion liability between coal seams: A thermogravimetric study

The spontaneous combustion liability of coal can be determined by using different experimental techniques.These techniques are well-known in their application,but no certain test method has become a standard to prove the reliability of all of them.A general characterisation which included proximate and ultimate analyses,petrographic properties and spontaneous combustion tests(thermogravimetric analysis(TGA)and the Wits-Ehac tests)were conducted on fourteen coal and four coal-shale samples.The spontaneous combustion liability of these samples collected between coal seams(above and below)were predicted using the TGA and the Wits-Ehac tests.Six different heating rates(3,6,9,15,20 and 25
C/min)were selected based on the deviation coefficient to obtain different derivative slopes and a liability index termed the TGspc index.This study found that coal and coal-shale undergo spontaneous combustion between coal seams when exposed to oxygen in the air.Their intrinsic properties and proneness towards spontaneous combustion differ considerably from one seam to the other.The Wits-Ehac test results agreed with the TGspc results to a certain extent and revealed the incidents of spontaneous combustion in the coal mines.

Thermogravimetric study of the effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal

Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss activation energy, oxidation activation energy and combustion activation energy were calculated by an integral method using the Coats-Redfen formula. The results show that the tendency for spontaneous combustion of three coal samples (judged by the activation energy) falls in the order: CYW>YJL>SW. The oxidation activation energy and combustion activation energy of coal protected by the PVA oxygen-insulating barrier increased. A significant increase in the combustion activation energy was noted, especially for the CYW coal where the in-crease was 28.53 kJ/mol. Hence, oxidation of the protected coal samples was more difficult. The PVA oxygen-insulating barrier helps to prevent spontaneous combustion of the coal.

Thermal analysis of olive tree pruning and the by-products obtained by its gasification and pyrolysis: The effect of some heavy metals on their devolatilization behavior

In this work, the effect of the presence of nickel and lead in thermal decomposition of olive tree pruning (OTP), OTP-char and OTP-ashes was studied by thermogravimetry. Experiments were conducted in two kinds of atmosphere (nitrogen atmosphere and oxidizing atmosphere with 20% of O2) at a heating rate of 10 ℃/min. This investigation describes the chemical, physical and fuel properties of the OTP, which shows a similar composition to other lignocellulosic materials such as hazelnut husk and wood sawdust. In addition, SEM analysis indicated that OTP-char surface is higher than OTP surface with plenty of holes and channels. It makes the char an ideal support for metal retention specially for Pb metal (OTP retained 8.55 mg/g whereas OTP char retained 11.57 mg/g). On the other hand, metal retention occurred by adsorption or ion exchange, according to the IR spectrum of the samples. The results of thermogravimetric tests proved that the presence of lead did not have a strong effect on the decomposition of the samples, since TG and DTG curves were very similar. However, nickel increased the mass loss rate, accelerating the decomposition process, showing higher peaks in DTG curves. Additionally, for temperatures higher than 360 ℃, the volatilization of the samples was improved in the nickel-polluted sample, achieving a higher mass loss, getting more energy from the biomass and reducing the quantity of residues left after the process.

Thermal decomposition analysis of coal-waste sludge and coal-sunflower seed husk blends

The thermal decomposition analysis of coal-pharmaceutical waste sludge,coal-sewage waste sludge blends and coal-sunflower seed husk blends are studied by TG dynamic runs at the heating rate of 20 ℃/min within the temperature range of 25 ℃-900 ℃.The effect of different kinetic models on the determination of kinetic parameters of thermal decomposition has been investigated.Results show that for coal-pharmaceutical sludge blend,coal-sewage sludge blend and coal-sunflower seed husk blend the optimal model functions are the three-dimensional diffusion reaction,2-dimensional and 3-diemensional nucleation and growth reactions,respectively.The Arrhenius kinetic parameters of the pre-exponential factor and activation energy of blends,as well waste sludge and sunflower seed husk only are proposed.

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。

Pyrolytic and kinetic analysis of coastal plant Xanthium sibiricum

The fuel properties of coastal plant Xanthium sibiricum were investigated in thermogravimetrics.The distributed activation energy model was employed in the kinetic analysis and a simplified mathematical model that can predict the thermogravimetry curves was proposed.The results show that the initial decomposition temperature tends to increase with the heating rate.The distributed E values ranged from 169.08 to 177.43 kJ/mol,and the frequency factor values ranged from 6.59× 10~8 to 1.22×10^(12)/s at different conversion rates.Furthermore,the prediction made with the simplified mathematical model perfectly matched the experimental data,and the model was found to be simple and accurate for the prediction of devolatilization curves.

Characterization of the Thermo-Microstructural Analysis of Raffia Palm Fibers Proposed for Roofing Sheet Production

Raffia fibres are made from fibrous branches and leaves of Raffia palm. The membrane on the underside of each individual frond leaf is taken off to create a long thin fiber. They are usually waste materials which cause a great environmental degradation. The characterization of Raffia palm fibers/ particles was investigated through X-ray diffractometer (XRD), thermogravimetric analysis (TGA/DTA), Fourier transform infrared spectrometry (FTIR), Scanning electron mi croscope with energy dispersive spectrometer (SEM/EDS) and Atomic force microscope (AFM). The various results obtained are equivalent to those of other agro-waste materials generally used in roofing sheets composites production. Hence, this work shows that Raffia palm fibers/particles can be a useful material for cement mortar composites production which can be used for production of roofing sheets.

Comparative Evaluation of Thermogravimetric and Refractive Index Techniques in Determining Biodiesel Yield

Biodiesel is a clean and renewable resource that consists of mono-alkyl esters of long chain fatty acid, which could be obtained from the transesterification reaction of vegetable oils and animal fats with alcohols and catalysts. Biodiesel yield has typically been determined using expensive and laborious techniques. The attempt of this study was to examine the potential of quantifying the biodiesel conversion in real time using refractive index in transesterification process of canola oil with methanol and KOH. Biodiesel yields at five different mixing intensities and reaction times were measured using a refractometer. The measured results were then compared with analytical data obtained from thermogravimetric analysis (TGA) technique over a temperature range of 25℃ - 600℃. Experimental results indicated that the FAME conversions at different mixing intensity and reaction time measured from refractometer correlated well to the relative weight losses from TGA method with R2 = 0.93 (p ≤ 0.05);however, the refractometer may over-estimate the biodiesel yield when the reaction rate was too low. Overall, the refractometer technique is cheaper and easier to manage and could provide a reliable prediction of biodiesel yield in real time.

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。

Dielectric and Thermal Analysis of a Shrub Leaf for the Modeling of Forest Fire

Most Mediterranean regions face a high risk to forest fires, estimation and anticipation of this risk modeled as a stochastic propagation process reproduces well some fire properties. This model needs information on the behavior of the bio-physical properties of vegetation associated to combustion. An experimental study to analyze the structure of a leaf of Laurel shrub at different biological stages is presented; it allows following the structural exchanges induced on the leaf by the effect of increasing temperature. For this purpose, both dielectric and TGA （Thermogravimetric Analysis）/DTA （Differentialthermal Analysis） was performed to a better understanding of the pyrolysis phenomenon. The results obtained provide information on the process of thermal degradation caused by fire. The evolution of the leaf impedance as a function of the applied frequency characterizes the moisture loss in plant species during pyrolysis. The dielectric response confirms the proposition to the equivalent circuit of the leaf as a composite of liquid and solid parts. The TGA/DTA results detected the behaviour of the solid parts in the fire under a constant heating rate, and were able to show all the transformation subjected by the Laurel leaf until ignition and all the gases released during it.