Thermomechanical Analysis Techniques Research Articles

An Environmentally Friendly Mineral-Free Tanning of Animal Skins – Sustainable Approach with Plant Resources

An eco-friendly mineral-free process for tanning has been developed in the present investigation, which is based on replenishable plant resources. Significant reduction in total dissolved solids and chlorides compared to conventional tanning method was observed in the new process. Tara and jatropha seed oil were employed for tanning of animal skins. The thermal and morphological characteristics, resistance to fungal and organoleptic properties of the tanned leathers were analyzed by using shrinkage, differential scanning calorimetric and thermo-mechanical analysis techniques. It has been proved that the properties of the tanned leathers are better than that of conventional vegetable tanned and comparable to chrome tanned leathers. The cross section of fibre structure indicates uniform structure and fibre bundles seem to be less dispersed when analyzed through scanning electron microscope. The tanned leathers exhibited better physico-chemical and organoleptic properties. The new tanning system also exhibited cost advantages due to reduction in chemicals consumption and savings due to reduced effluent treatment costs. The developed tanning process reduces the generation of toxic waste compared to mineral tannages, which reduces the environmental impacts. Hence, this techno-commercial study provided a viable and versatile solution for mineral-free tanning for commercially sustainable processing through cleaner process options.

Total salinity elimination during preservation of animal skins: a sustainable approach through benign alternatives.

Use of sodium chloride to preserve animal skins and hides is becoming increasingly untenable due to stringent environmental regulations. In the present research work, a combination of sparingly soluble alkali and water-soluble polymer of ethylene oxide has been used to preserve skins with an objective of total elimination of common salt for preservation. A comprehensive study has been made for evaluating various parameters, such as dehydration and rehydration behaviours of skins, microbial growth, emission loads and physico-chemical characteristics of the cured skin to validate the salt-free preservation system developed. The shrinkage temperature, denaturation temperature and mechanical strength of tanned leather were analysed by using shrinkage, differential scanning calorimetric and thermomechanical analysis techniques. The new curing system has been found to be effective in preserving the skin as indicated by the various parameters studied and the final leather quality. The significant reduction in total solids content such as dissolved solids and suspended solids present in the effluent compared to conventional preservation method is evident from environmental impact assessment studies.

Effect of ash fraction and particle size on ash deposition during pulverized coal combustion

Coal is an important energy source to increase consumption continuously. However, the ash residues from coal combustion have produced ash deposition that causes slagging and fouling in boilers. The goal of this study is to examine the characteristics of ash deposits (i.e., the effects of the ash fraction and particle size) in pulverized coal combustion. For this study, five coals (Suek, Macqurie, Berau, Lanna and Vitol) are used, which have similar chemical components in the ash but differences in the ash fraction. A Thermomechanical analysis technique (TMA) and Drop tube furnace (DTF) are used to analyze the tendencies in the ash fusibility and deposition with temperature, respectively. Moreover, the size and morphology of the fly ash are analyzed for physical changes by using a particle-sizedistribution analyzer and Scanning electron microscopy (SEM), respectively. In the TMA results, all coal types have a similar fusibility because of the similar chemical components in the ash. The order of the deposited mass is Suek, Macqurie, Berau, Vitol and Lanna in accordance with the ash fraction in the DTF. The ash fraction in coal is a major factor in the ash deposit according to these results. The size of the fly ash changed compared to that of the raw coal according to the results of a particle-size analysis and SEM owing to physical processes such as fragmentation, shedding and coalescence during coal burning. On this basis, a deposition model is developed with the ash fraction and particle size. The model results are in good agreement with the measurements. The results demonstrate that the particle size and ash fraction influence the deposit.

Greener approach to leather tanning process: d-Lysine aldehyde as novel tanning agent for chrome-free tanning

A greener and eco-friendly method to leather tanning process has been developed in the present investigation, which is based on d-Lysine aldehyde complex. This can be considered as a substitute for chrome-free tanning process. The physico-chemical and morphological characteristics, resistance to collagenolytic activity and organoleptic properties of the d-Lysine glutaraldehyde tanned leather were evaluated in terms of environmental impact assessment. The shrinkage temperature, denaturation temperature and mechanical strength of tanned leather were analysed by using shrinkage, differential scanning calorimetric and thermomechanical analysis techniques. It has been shown that the above properties of the tanned leather are better than that of glutaraldehyde alone or equal to chrome tanned leather. The density of the fibre structure throughout the cross section indicates the even structure and fibre bundles seem to be less dispersed compared to glutaraldehyde alone; were analysed by using scanning electron microscopic and atomic force microscopic techniques. This tanning tanned leather demonstrated a higher resistance to collagenolytic activity than conventional tanned leather. The tanned leather exhibited good fullness, softness, smoothness, colour and general appearance compared to glutaraldehyde alone. The significant reduction in total solids content such as dissolved solids and suspended solids present in the effluent compared to conventional tanning method is evident from environmental impact assessment studies. This tanning process has the cost advantages due to the possible decrease in chemicals consumptions and net saving from the reduced effluent treatment costs. The improved tanning process reduces generation of toxic waste compared to chrome tanning process and can be regarded as eco-friendly, which reducing the environmental impacts and contributes to the development of greener or cleaner process.

05/02395 Investigation of coals and blends deposit structure: measuring the deposit bulk porosity using thermomechanical analysis technique

05/02395 Investigation of coals and blends deposit structure: measuring the deposit bulk porosity using thermomechanical analysis technique

Effect of pre-heat treatment on the static and dynamic thermo-mechanical properties of ultra-high molecular weight polyethylene

In the present work, a dynamic thermo-mechanical analysis technique has been used to investigate the effect of pre-heat treatments on the visco-elastic properties of Ultra-High Molecular Weight Polyethylene (UHMWPE) as a function of frequency and temperature. These properties include storage modulus ( E′) and loss modulus ( E″). The UHMWPE specimens were pre-heated at 50, 80 and 100 °C for periods of 2 and 4 h, respectively. The effect of these pre-heat treatments on the quasi-static mechanical properties (Young's modulus, yield strength, fracture strength, ductility and micro-hardness) has also been investigated. Finally, the degree of crystallinity of the UHMWPE has been measured as a function of pre-heat treatment time and temperature. The results show a strong dependence of most of these properties on the degree of crystallinity which is a function of pre-heat treatment temperature and duration.

Investigation of coals and blends deposit structure: measuring the deposit bulk porosity using thermomechanical analysis technique

This study investigated the deposit structure in terms of the bulk porosity for Australian bituminous coals and blends that were fired in a pilot-scale test furnace. The first part of this study estimated all the deposits bulk porosity using two indirect techniques: a density measurement technique and by scanning electron microscopy (SEM). The results showed a significant difference between the two techniques. The density measurement underestimated the bulk porosity of the deposit due to the closed pores within the deposit structure. The second part of this study proposed a novel experimental approach to measure the changes in the deposit bulk porosity at elevated temperatures using thermomechanical analysis technique (TMA). The TMA bulk porosity measurements were comparable with the SEM results.

Preparation and characterization of CaTiO3–(Li1/2Nd1/4Sm1/4)TiO3 microwave ceramics by a sol–gel combustion process

A novel sol–gel combustion process was adopted to synthesize reactive ceramic powder with composition of 0.25 CaTiO3–0.75 (Li1/2Nd1/4Sm1/4)TiO3, and microwave dielectric ceramics were prepared at different sintering temperatures using the synthesized powder. The combustion behavior of citrate gel and the sintering feature of the synthesized powder were evaluated by using differential thermal analysis–thermogravimetric analysis and thermo-mechanical analysis techniques, respectively. The citrate gel exhibits a self-propagating behavior after being ignited in air at room temperature. The as-burnt powder is so highly reactive that it can be transformed into single-phase perovskite at 900 °C and it can be sintered at 1100 °C. The effects of sintering temperature on the density, microstructure, and dielectric properties of the sintered ceramics were investigated. The maximum values of density, dielectric constant, and Q×f were achieved after sintering at 1200 °C. At 1200 °C, very dense ceramics with uniform grains and good dielectric properties with a dielectric constant of 123.8, a Q×f value of 5110 (at 3.7 GHz), and a τf value of +12.5 ppm/°C were achieved via the sol–gel combustion route.

Determination of the viscosity of an amorphous drug using thermomechanical analysis (TMA).

To evaluate thermomechanical analysis (TMA) as a technique for determining the viscosity of amorphous pharmaceutical materials. This property of amorphous drugs and excipients is related to their average rate of molecular mobility and thus to their physical and chemical stability. Indomethacin was selected as a model amorphous drug whose viscosity has previously been reported in the literature. A Seiko TMA 120C thermomechanical analyzer was utilized in isothermal penetration mode to determine the viscosity of the amorphous drug over the maximum possible range of temperatures. Using a cylindrical penetration geometry it was possible to accurately determine the viscosity of amorphous indomethacin samples by TMA over the temperature range from 35 to 75 degrees C. The results were consistent with those reported in the literature using a controlled strain rheometer over the range 44-75 degrees C. The limiting lower experimental temperature for the TMA technique was extended to significantly below the calorimetric glass transition temperature (Tg approximately 42 degrees C), thus allowing a direct experimental determination of the viscosity at Tg to be made. Thermomechanical analysis can be used to accurately determine the viscosity of amorphous pharmaceutical materials at temperatures near and above their calorimetric glass transition temperatures.

A precision capacitance cell for measurement of thin film out-of-plane expansion. II. Hygrothermal expansion

The data reduction techniques necessary for utilizing the capacitance cell described previously by us for thickness measurements [C. R. Snyder and F. I. Mopsik, Rev. Sci. Instrum. 69, 3889 (1998)] in a humid environment are presented. It is demonstrated that our data reduction techniques provide thicknesses that are equivalent to those measured under dry conditions within the expected experimental uncertainty. The utility of this technique is demonstrated by the measurement of the hygrothermal expansion (swelling) of a bisphenol-A based epoxy with novolac hardener and fused silica filler. Our technique is shown to have a higher sensitivity than most current thermomechanical analysis techniques and is readily amenable to humid conditions.

Curing conditions effects on the characteristics of thermosetting adhesives-bonded wood joints

Thermomechanical analysis (TMA) results indicate that simple post-treatment (such as some postcuring) conditions capable of improving the mechanical performance of aminoplastic resins-bonded particleboard without any degradation do indeed exist. A model to describe the decrease in temperature under different conditions of a particleboard after hot pressing has been developed and shown to correlate well with experimental results of board temperature variation after pressing, both on cooling and during postcuring under different conditions. From this, conditions of temperature and time favourable to improve panel performance by postcuring treatments were also determined. The validity of the improvements forecasted under such conditions was then confirmed at molecular level for urea-formaldehyde (UF) adhesive/wood joints by TMA testing, and finally confirmed by testing the mechanical performance of laboratory UF-bonded boards prepared under the postcuring treatment conditions identified. Noticeable improvements in several UF-bonded board properties such as internal bond (IB) strength, thickness swelling, MOE and MOR were observed by implementing short postcuring periods at temperatures much lower than pressing temperature. The panels performance improvements observed were explained on the basis of the shifts in relative importance of already described and well-known molecular level rearrangements of the cured adhesive network in modern, lower formaldehyde content UF adhesives. The conclusion was that modern, lower formaldehyde content UF adhesives can considerably benefit from short, hot postcuring periods as regards board performance, a trend in clear contrast with the degradation and loss of performance this practice was known to induce in the older, very much higher formaldehyde content aminoplastic resins of the past. The coupling of the simple and very rapid TMA technique with the developed model allows the rapid scan of many other post-treatment schedules and thus to forecast other still possible improvements in the performance of UF-bonded and other-adhesives-bonded particleboard.

Use of Thermomechanical Analysis To Quantify the Flux Additions Necessary for Slag Flow in Slagging Gasifiers Fired with Coal

Coals with high ash fusibility temperatures are utilized in slagging gasifiers with the addition of a flux in order to lower ash melting temperatures and slag viscosity. Recently, thermomechanical analysis (TMA) has emerged as a technique that can characterize coal ash and slag behavior. The progressive shrinkage of heated coal ash samples mixed with calcium flux (CaO) has been measured using TMA. The resulting shrinkage has been correlated with the viscosity measured in a rotating bob viscometer for the same samples in order to quantify flux levels necessary for the viscosity required for coal fired slagging gasifiers (15−25 Pa·s). For this viscosity range, shrinkage levels in the range of 10−95% were obtained, indicating that the TMA technique has the potential to quantify the necessary flux additions.

The measurement of the glass transition temperature of mesophase pitches using a thermomechanical device

A thermomechanical analysis (TMA) technique is presented for the measurement of the glass transition temperature ( T g) of glassy pitch materials. Pitches with varying mesophase content have been used for the T g determination. In this technique, the linear expansion of a mesophase pitch sample with respect to temperature is determined by means of a dilatometer. The change in the coefficient of thermal expansion (CTE) of the pitch materials was found to be significant at the glass transition temperature. Therefore, the measurement of the CTE of the specimen with respect to temperature revealed the glass transition temperature. This technique was found to be very sensitive and easily executable. Results from the TMA technique show good agreement with those from differential scanning calorimetry (DSC). The TMA technique was found to reproduce the T g value for the mesophase pitch samples within ± 2 °C. In many cases, the value of T g from the dilatometer was much more definitive than that obtained from DSC, especially for the mesophase pitch samples. A linear correlation for T g as a function of Mettler softening point temperature ( T s) is developed and compared with that in the literature.

Evaluation of aging characteristics of bituminous roof coverings by thermo-mechanical analysis (TMA)

Four bituminous roof coverings have been subjected to various aging procedures including heat, UV irradiation and temperature/rain cycling. A specially modified TMA technique has been used for evaluation, depending on measurements of softening temperature. A comparison with mechanical test data has also been made. Some conclusions have been drawn with respect to influence of heat and UV radiation on the rate of degradation.

Thermomechanical analysis of linear aromatic polyesters

AbstractThe thermomechanical properties of linear aromatic polyesters, studied using thermomechanical analysis techniques, have been related to the chemical structure and methylene chain length. An increase in the number of methylene groups, the use of an asymmetric diacid, or random copolymerization of the repeating units of these polyesters, resulted in a lower linear thermal expansion coefficient α, a lower Vicat softening temperature Ts, a lower heat deflection temperature Td, and a lower glass transition temperature Tg. With longer methylene sequence lengths, the influence of the methylene groups on the thermomechanical properties is predominant, the data are closer together. The values are generally highest for the terephthalate series and lowest for the copolymer series. Glass transition temperatures calculated from group contributions and measured experimentally agreed. The deflection temperatures approximated the glass transition temperatures and the Vicat softening points the melting temperatures.

The Response of Textured Yarn Properties to Process Variables in Relation to Barré

A thermomechanical analysis technique has been used to characterize a set of false-twist pin-textured polyester yarns. These yams were generated under a wide range of texturing conditions from two distinct lots of fully-drawn feed yarn which differed in orientation. The analysis yielded a variety of thermomechanical yarn parameters. One set of parameters had some of the properties of an “effective yarn-texturing temperature.” A different set of parameters correlated with the tensile, shrinkage, or crimp parameters of the yarns and were sensitive to the effects of feed-yarn orientation differences. Other parameters correlated with textured yarn dyeability. Measurements of this type should prove valuable in the quality control of textured yarns and in the diagnosis of yarn faults.