Differential Thermal Analysis Tests Research Articles

Effect of flame retardants and 1% stabiliser on thermal decomposition and physics properties of thermoplastic polymer due to TGA and DTA tests

This work introduces seven various polymer samples blended in a twin-screw extruder with flame retardants (FR), and an additive, which is a 1% Stabiliser, to investigate thermoplastic polymer melting, thermal decomposition, and melting moderates. The reduction method is used to analyze its melting points, physics and chemical properties, and thermal decomposition. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) tests are known as thermal analysis tests. It was established that halogenated flame retardants have little effect on reducing the rate of gas escape from polymer melt which affects the viscosity, as it was found. Thus, the APP and FR245 in Polymer help in some polymer leftovers. All samples were treated with flame retardants and no clay, melted completely, at the end of the test some samples did change. All these results investigated by (the XRD) test either, Scanning Electron Microscopic (SEM) or Digital images have been used also applied Limiting oxygen index (LOI) test, in the previous work for the same samples of polymers to verify the results and record a more precise outcome to draw the relationship between melting and dripping behavior via the following studies due to the furnace test which is modulated and calibrated. As a result, the addition of clay together with conventional flame retardants enhances the overall thermal stability forming the polymer. The compatibles help in improving the dispersion of the clay in polymer and reduce the rate of gas escape from polymer melt affecting the viscosity.

Sintering behavior of ceramic ethylene‐propylene‐diene rubber/pyrophyllite/zinc borate composites

AbstractCeramic polymer materials have great future applications in the field of fireproof materials. However, ceramic polyolefins have shortcomings such as few available inorganic fillers, high sintering temperature, and low flexural strength. Therefore, achieving rapid sintering of ceramic ethylene‐propylene‐diene rubber (EPDM) is an urgent problem that needs to be solved. Herein, we prepared ceramic EPDM materials using pyrophyllite as aggregate and zinc borate as flux. The materials were prepared using a mixer and sintered in a muffle furnace at 850 and 1000°C. The flexural strength of the sinter residue was tested by a material testing machine. The microstructure changes during the ceramification process were characterized using scanning electron microscopy (SEM), thermogravimetric analysis (TG), derivative thermogravimetric analysis (DTG), differential thermal analysis (DTA), and x‐ray diffraction (XRD). The results indicated that the EPDM filled with pyrophyllite and zinc borate had a flexural strength of 2.6 MPa after sintering at 850°C. After sintering at 1000°C, its flexural strength further increased up to 12.3 MPa. The SEM results indicated that as the temperature increased, the zinc borate melted and filled in the space among pyrophyllite particles, and the zinc borate and the pyrophyllite were sintered into a dense whole. The TG, DTG and DTA testing results indicated that the melting and decomposition behaviors of the pyrophyllite‐zinc borate mixture changed compared with pure pyrophyllite and zinc borate. The XRD results indicated that during the sintering process, the crystalline structure of the zinc borate and the pyrophyllite gradually transformed into a quartz‐based crystalline structure. It is promising that the ceramic polyolefin materials are prepared by the pyrophyllite/zinc borate combination.

How Pretest Temperatures Change the Cold Hardiness of Grapevine (Vitis Vinifera L. Cv. Karaerik) Dormant Buds?

ABSTRACT The aim of this study was to confirm the hypothesis that pretest temperature changes could alter the cold hardiness of the grapevine dormant buds and eventually the result of differential thermal analysis (DTA) test. For this reason, dormant buds of ‘Karaerik’ grape cultivar were collected at different times and tested using different DTA procedures. Dormant buds taken at nine different sampling temperatures (8, 6, 5, 3, −1, −3, −4, −5, and −9°C) were exposed to freezing test according to three DTA test approaches (TestA-A, TestA-4 and Test20-4, to represent ambient storage and ambient test, ambient storage and 4°C test, and 20 ± 2°C storage and 4°C test or standard DTA method, respectively) to verify our hypothesis in 2015–16 and 2016–17. The LTE (low temperature exotherm) temperatures were determined as the indicator of death of primary buds at grapevines’ dormant buds, tested according to TestA-A approach, TestA-4 approach and Test20-4 approach (the standard methodology). It was found that temperature changes such as rapid cooling, warming and thawing in the TestA-4 approach, and warming-cooling and melting-cooling in the Test20-4 approach altered LTE values of dormant buds depending on the test start temperature. It was determined that the LTE values of dormant buds tested according to TestA-4 and Test20-4 approaches were higher than that of the ones tested with TestA-A approach. Compared to TestA-A approach, the LTE values of dormant buds were between 0.00 and 4.00°C in the TestA-4 approach and 0.00 and 2.77°C in the Test20-4 approach based on temperature changes. As a result, to achieve reliable, and consistent LTE results at DTA tests, it was determined that dormant buds should be brought into laboratory by keeping the temperatures at the sampling time, prepared for test at these temperatures and to start DTA test from these temperatures is a right approach.

The Relationship Between Bud Size and Exotherm Formation in Dormant Buds of Grapevine

This study was conducted to determine the relationship between bud size and low temperature exotherm (LTE) formation in dormant period of grapevines. For this purpose, primary and secondary buds of Karaerik (Vitis vinifera L.) and 53 Pazar 01 (Vitis labrusca) genotypes which are known to have differences between the bud structure and size, were examined separately. In the study carried out in 2016-2017 and 2017-2018 dormant periods, low temperature exotherms were determined by Differential Thermal Analysis (DTA) method in order to determine the freezing point of the buds. Dormant buds of grapevine size were determined by microscopic imaging of the sections taken after histological procedures. It was demonstrated by the DTA test that the buds with different histological structures had different character and number of LTE. In this study, it was determined that bud samples belonging to Vitis vinifera L. form exotherm at lower temperatures than bud samples belonging to Vitis labrusca species. For both genotypes, it was determined by the histological determinations that the primary buds had a larger structure than the secondary buds. In the study, it was found that the buds with an area less than 0.010 mm2 did not produce LTE. As a result of the study, it was found that the bud structure and size were effective on LTE formation of grapevine dormant buds.

Preparation and Characterization of Conductive Plastics Using Cassava Peel Waste and Addition of CuSO4

This study investigated the characteristics of a conductive plastic based on root starch and CuSO4 filler. The mixture variation was (95:5)%; (90:10)%; (85:15)%; (80:20)% and (75:25)%. Glycerol is used to change the material as desired (plasticizer) which is called a plasticizer. The method used in the manufacture of this material is melt intercalation. Mechanical testing includes tensile strength (tensile strength) and elongation at break. Thermal testing was done using DTA (Differential Thermal Analysis) and material conductivity testing. The characterization results showed that the optimum starch composition: CuSO4 (75:25)% had a conductivity value of 7.3 x 10-2S.m-1, a thermal test value of 410ºC. The optimum tensile strength value occurs in the composition (80:20)% with a value of 4.606 MPa

Thermodynamic description, hardness and electrical conductivity of the Bi–Ni–Zn system: Experiment and modeling

Selected ternary systems are chosen due to the significant interest of nickel alloys in the different industry such as electronic, chemical, automotive, marine etc. Chosen ternary system up to this paper has not been studied. The ternary system Bi–Ni–Zn has been experimentally and analytically tested. Temperatures of phase transformation were determined by differential thermal analysis (DTA) on 12 ternary samples. Obtained results by DTA test were compared with calculated vertical sections Bi–NiZn, Ni–BiZn and Zn–BiNi. Hardness and electrical conductivity were measured for some alloys. By using experimental results of hardness and electrical conductivity tests, mathematical model has been proposed for calculation of those properties along all composition ranges. Composition of alloys and phases in alloys annealed at 400 and 700 °C were determined by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS). Obtained results by EDS were compared with calculated isothermal sections at 400 and 700 °C. X-ray powder diffraction (XRD) tests were used for phase identification in all ternary samples. Used analytical method was Calphad method. Calculation of phase diagrams (three vertical sections and two isothermal sections) was performed by using thermodynamic parameters for constitutive binary systems. Good agreements between calculated phase diagrams and experimental data have been reached without introducing ternary thermodynamic parameters. Based on this conclusion liquidus projection and invariant reaction were calculated without additional experimental tests.

Differential Thermal Analysis of ‘Elberta’ and ‘Flavorich’ Peach Flower Buds to Predict Cold Hardiness in Georgia

Differential thermal analysis (DTA) has great potential as a quick and convenient cold hardiness determination method in plants. It measures freezing events inside of plant samples by detecting exotherm(s) produced when water changes from liquid to solid phase. DTA is highly sensitive to the experimental conditions and it has been reported to be ineffective among different fruit crops after acclimation of floral buds has occurred. The objective of this project was to establish DTA as a rapid and accurate method to predict peach floral bud cold hardiness from acclimation to deacclimation as compared with the traditional standard artificial freezing test. Floral buds of ‘Elberta’ and ‘Flavorich’ peach cultivars were subjected to DTA and artificial freezing tests throughout the winters of 2015–16 and 2016–17. Before deacclimation, two distinct exotherms, low-temperature exotherms (LTE) and high-temperature exotherms (HTE), were normally detected from floral bud DTA analyses. After deacclimation, DTA tests yielded only a few LTEs. However, incubation of floral buds at −2 °C overnight before the cooling process of DTA tests yielded an increased number of LTEs for both seasons in comparison with samples directly run using DTA without incubation. Similarly, after deacclimation started, the temperature in which LTE occurred was correlated (r = 0.59–0.86) with LT50 (lethal temperature that damaged 50% of floral buds) when DTA samples were treated overnight at −2 °C. In our study, pretreatment of floral buds at −2 °C overcame the inability of DTA to detect LTEs after deacclimation, which improved the ability and reliability of DTA to detect LTEs for more than 50% of the buds used per date per cultivar. DTA is a promising method to predict cold hardiness of peach plants.

Silica-Kaolin Mix Effect on Evaporative Pattern Castings Surface Roughness

Abstract The influence of the refractory coating which is a mixture of silica flour and kaolin on the surface roughness of the plate castings produced using evaporative patterns had been considered in this work. The kaolin was used as a binder and ratio method was employed to form basis for the factorial design of experiment which led to nine runs of experiments. Methyl alcohol at 99% concentration was used as the carrier for the transfer of the coating to the surface of the patterns. Pouring temperature was observed as a process parameter alongside the mix ratios of the coating. Attempts were made to characterize the refractory coating by using two methods; differential thermal analysis (DTA) and X-ray diffraction. Attempt was also made to characterize the casting material. Gating system design was done for the plate casting to determine the correct proportions of the gating parameters in order to construct the gating system properly to avoid turbulence during pouring of liquid metal. A digital profilometer was used to take the measurements of the surface roughness. It was observed that the mix ratio 90% silica flour-10% kaolin produced the lowest value of the surface roughness of the plate castings and had the lowest material loss in the DTA test. The pouring temperature of 650°C produced best casting.

Study on the ZnO-B<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> Glass-Ceramic with DTA, XRD and SEM

The ZnO-B2O3-SiO2 base glass was prepared with high temperature melting method. The base glass powder was investigated by differential thermal analysis (DTA) and the glass-ceramic was investigated by X-ray diffraction (XRD) analysis and scanning electron microscope (SEM). The results indicated that the structure adjustment of the base glass appeared around 595°C and the exothermic peaks turned up around 740°C and 860°C in the DTA testing. But the strength of the structure adjustment and the exothermic peaks was weak. The XRD results showed that the non-crystal glass was amorphous form without diffraction peaks appearing. The crystallization glass obviously contained crystals, which were more amount of ZnAl2O4 crystal and a small amount of NaAlSiO4 crystal. Through the SEM, the surface morphology of the glass-ceramic showed that the amount of the crystal was dense.

Thermal Study on Light Crude Oil for Application of High-Pressure Air Injection (HPAI) Process by TG/DTG and DTA Tests

High-pressure air injection (HPAI) in light oil reservoirs has proven to be a valuable improved oil recovery (IOR) process and aroused more attention worldwide. In this research, laboratory experiments were performed to study the potential of HPAI application in Keke Ya oilfield (Tarim Basin, China). Test oil and actual reservoir core samples were taken from Keke Ya oilfield, and rock composition was prior analyzed through X-ray method. The thermal behaviors of oil-only, cuttings, and oil-cuttings were studied by thermogravimetry/derivative thermogravimetry (TG/DTG), differential thermal analysis (DTA) tests, and also, rock composition and clay mineral type/relative content effects on light crude oil oxidation behavior were systematically investigated. The results show that Keke Ya oil has a favorable exothermic behavior, exhibiting apparent low-temperature oxidation (LTO), fuel deposition, and high-temperature oxidation (HTO) stages. An extended fuel deposition stage was observed by addition of cuttings. Smectite present in illite/smectite plays a positive role of catalyzing effects for oil oxidation in different reaction regions. In this study, it revealed that smectite is ranked first, illite or chlorite is ranked second, followed by kaolinite, in the aspect of catalytic ability for crude oil oxidation. The Arrhenius model was introduced for kinetics analysis. How these findings will provide guidelines to achieve high-performance HPAI projects is also discussed.

DTA of Rare-Earth Fe-Based Matrix Composites for Diamond Tools

Research focused mainly on Fe-based matrix composite (the wrapped diamond), used Fe powder to replace the expensive cobalt powder (Co-based matrix composite), and add the rare earth (RE) elements to reinforce the related physical properties of this Fe-based matrix composite for diamond tools. Conducted on the related matrix composite differential thermal analysis (DTA), in particular Fe-based matrix composite containing 35% iron powder (with RE or without RE) Were discussed for DTA and the package insert forces. DTA and the analysis is consistent with the empirical formula. By hot pressing the composite with diamond as the research object, having researched the relationship among the heat capacity (CP) at constant pressure and other related physical parameters （the package inserts force and E etc.）. Take 35%Fe-based powder composite materials for diamond tools (with RE or without RE) as the research objiect, combining analysis of the problem for the porosity, and the densification, and the package inserts force, and the DTA tests, which the addition manner of rare earth, add form , and quantity are determined, so that the changes laws of DTA curve and heat capacity (CP) of Fe-based composite containing 35% iron powder( with the RE) are similar to the that of pure Co composites. Apply these laws to improve the hot pressing technology and mechanical properties of the diamond tools (bending strength, impact toughness, hardness and porosity) and so on

Preparation and Catalytic Activity of Fe<sub>2</sub>O<sub>3</sub>/CNT to Thermal Decomposition of Ammonium Perchilorate

CNT (Carbon nanotube)-supported Fe2O3 combustion catalyst was prepared via a sol-gel method in order to promote the thermal decomposition of ammonium perchilorate (AP). XRD (X-ray diffraction) analysis proved that the product was nanosized hexagonal α-Fe2O3 loading on carbon substrate. TG (Thermogravimetry) and DTA (Differential Thermal Analysis) tests showed that Fe2O3/CNT could accelerate AP thermal decomposition at relatively low temperature. It was suggested that the improvement of the catalytic activity was associated with the dispersion of Fe2O3 nanoparticles and the enlargement of active region.

Pulsed laser deposition of corrosion protective Yttrium Oxide (Y 2O 3) coating

Among ceramics and oxides, Yttria (Y 2O 3) films have been widely investigated as potential corrosion protective coatings largely on account of their wear resistant and non-wettable properties. Results presented here describe successful use of pulsed laser deposition (PLD) technique for deposition of thin film Yttria coating on stainless steel substrates. Deposited Yttria coatings have been characterized in terms of their microstructure, crystalline phase and hardness using Scanning Electron Microscope (SEM), X-ray diffraction (XRD) and scratch test techniques, respectively. Characterization tests of these coatings of thickness up to 50 μm have shown strong bonding with substrate surface and a high degree of homogeneity and compaction. Resistance of these PLD based Yttria coatings to molten uranium have also been studied via Differential Thermal Analysis (DTA). Our results on DTA tests evaluating compatibility of the Yttria coatings with molten uranium have established the excellent corrosion resistance property of such Y 2O 3 coatings when exposed to molten uranium.

Influence of Alloying Elements on the Thixoformability of a Chromium Steel

This paper deals with the examination of the influence of alloying elements on the thixoformability of a chromium steel. It focuses on the liquid fraction curves of various chromium steels with and without modification of composition. The liquid fraction versus temperature has been obtained by MTData, a thermodynamic prediction package, and by Differential Thermal Analysis (DTA), limited to low heating rates. The correlation between liquid fraction and temperature has been studied. The effect of modifications of composition and of heating rate was observed. First, the thermodynamical calculations allow the study of the influence of alloying elements with variations in chemical composition. Secondly, the DTA tests offer the possibility to observe the influence of heating rate on liquid fraction curve parameters. All these results lead to the identification of the initial parameters necessary to perform inductive heating and quenching tests, and so to approach the industrial process.

Evaluation of phase equilibria in the Nb-rich portion of Nb–B system

The phase equilibria in the Nb-rich portion of Nb–B system have been evaluated experimentally using metallographic analysis, differential thermal analysis (DTA) and X-ray diffraction. It showed that Nb ss (solid solution) and NbB are the only two primary phases in the 0–40 at.% B composition range, and the eutectic reaction L ↔ Nb ss + NbB exists, instead of the generally accepted reaction L ↔ Nb ss + Nb 3 B 2 , as indicated in the Nb–B phase diagram. The Nb 3B 2 phase, however, forms by the peritectoid reaction Nb ss + NbB ↔ Nb 3 B 2 . DTA tests were conducted on annealed Nb–14B, Nb–16B, Nb–18B and Nb-40B alloys, and temperature and heat of phase transition were determined. The eutectic reaction ( L ↔ Nb ss + NbB ) temperature was determined to be 2104 ± 5 °C, and the heat of phase transition was estimated as 22–30 kJ/mol, depending on the method of calibration used. The thermal event associated with peritectoid reactions was not observed in DTA curves due to sluggish solid state transformation, but the thermal annealing experiments show that peritectoid temperature is above 1900 °C.

Nucleation and crystal growth of glasses produced by a generic plasma arc-process

The feasibility to crystallise a glass prepared by thermal plasma vitrification of hospital wastes to produce a glass-ceramic suitable to be used as a construction material was investigated by using differential thermal analysis (DTA) and X-ray diffraction (XRD). Two crystallisation exotherms in DTA were attributed to the formation of wollastonite and a crystalline phase belonging to the melilite group (gehlenite or akermanite). DTA tests have shown that the glass is not suitable for bulk crystallisation and must be converted into a glass-ceramic by using the sintering process route through a single crystallisation step at 1000 °C for 10 min.

Freeze Tolerance of `Braeburn' Apple Shoots

Differential thermal analysis (DTA) and tetrazolium triphenyl chloride (TTC) were done on shoots of 4-year-old `Braeburn' apple trees for 3 years. The trees acclimated slowly in autumn. If cold temperatures last long enough in winter, shoots will acclimate as low as –40C. Shoots are sensitive to warm temperatures and deacclimated rapidly. An attempt to run a controlled test on freeze resistance of `Braeburn' did not respond to DTA. Moisture samples indicated trees were freeze dried. Different sets of trees were rehydrated and showed an exotherm pattern. Exotherms could be seen after 3 days at 26C, 14 days at 10C, and 21 days at 4C. Another controlled freeze test was performed on 1-year-old `Braeburn' trees. Trees were acclimated outdoors. An exotherm pattern could be seen upon DTA analysis. After artificial freezing, DTA and TTC tests showed pith killed at –24C, primarily xylem at –28C, and all tissue at –35C. After freezing, trees were placed in a greenhouse and warmed over 2 months. Upon dissection, we found xylem produced before freezing was dead, but a large amount of new xylem was generated. Trees appeared to have normal leaf and shoot growth for about a month, but eventually wilted and died. Dissection of these showed the same results as the first set dissected. New xylem evidently was not enough to carry the growth of the trees.

Relation between melting behavior and physical structure in polymers

AbstractThe phenomenon of double melting, as manifested by two characteristic endotherms in the melting region on a differential thermal analysis (DTA) scan, has been studied in nylon 66 and polystyrene as a function of sample treatment by annealing or drawing. A variety of techniques were used in these studies including DTA, x‐ray diffraction, electron microscopy, and mechanical testing. It is shown that the two endotherms are not caused by a bimodal crystal size distribution, by recrystallization, by orientation changes, or by phase changes. It is proposed that one endotherm is caused by the melting of foldedchain crystals, while the other is due to the melting of less perfect bundle crystals. This view is well supported by the results, especially by the DTA measurements made at different heating rates. Published data on the thermal behavior of annealed and drawn poly(ethylene terephthalate) and on polyethylene crystallized at various pressures may also be explained on this basis if it is allowed that in polyethylene the chains may be more extended.