INVESTIGATION ON THE MORPHOLOGICAL AND THERMAL PROPERTIES OF POLYLACTIC ACID/POLYCAPROLACTONE LOADED WITH HALLOYSITE NANOTUBES AND BASALT FIBER

This paper is focused on the analysis of the morphological and thermal properties of the biomedical composites, polylactic acid (PLA) and polycaprolactone (PCL) matrix, reinforced with basalt fibers (BFs) and using halloysite nanotubes (HNT) as filler material. Four different composites, viz. PPHB 1, PPHB 2, PPHB 3 and PPHB 4, are obtained by varying the weight fractions of these materials using twin-screw extrusion followed by injection molding. The morphological characterization is performed on these composites using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. SEM reveals homogenous and strong bonding between the matrix, reinforcement and filler. The BF are well embedded in the matrix with a random orientation. No formation of voids and cracks is observed. The functional groups present and the types of vibration experienced by the chemical bonds were observed in the FTIR spectra. The composites are subjected to thermal testing such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The PPHB 2, which contains 80% PLA, 10% BF, 7% PCL and 3% HNT, has the highest degree of crystallinity, as revealed by DSC, and exhibits the most optimum thermal degradation characteristics as indicated by TGA.

Dry Cationic Friction Reducers: New Alternative for High TDS Slickwater

Currently, well stimulation in North America has evolved almost entirely to slickwater fracturing with friction reducers (FRs). Some parts of North America are notorious for their poor water quality, so wells are commonly treated using high total dissolved solids (TDS)-containing flow-back or produced water. Cationic FRs are usually applied in these systems due to their tolerance to multivalent cations in such waters. Additionally, dry friction reducers have gained momentum for better economics and logistics. In this paper, a dry cationic FR is systematically studied with respect to its "on the fly" hydration capability, friction reduction, mechanical stability, compatibility with other anionic chemical additives, and thermal stability in different levels of TDS brines. The cationic FR solution was subjected to varying shearing rates to understand its hydration capability, friction reduction, and mechanical stability. Its compatibility with anionic additives, such as a scale inhibitor, was also tested in a laboratory friction loop. Thermal stability of the cationic FR solution was studied at 150°F using a viscometer and Multi-Angle Laser Light Scattering (MALLS) method to obtain molecular weight information. The charge characteristics of the cationic FR, indicative of self-degradation properties, with exposure to heat, were also studied. Potential formation damage of the FR solution was evaluated with core flow tests in the absence of oxidizing breakers. Friction reduction and hydration tests show that the FR performs well in high TDS waters, even at low temperature, reaching its peak performance rapidly. The cationic FR possesses high mechanical stability even after being exposed to high pumping rates in the friction loop. It is well known that cationic FRs are not compatible with polyanionic scale inhibitors; in this study, a compatible scale inhibitor, SI-1, is identified. Additionally, there has historically been hesitation to use such cationic materials due to concerns of formation compatibility with negatively charged source rocks or flocculation in water treatment plants. Thermal testing with cationic FRs reveals that the material degrades to anionic without the aid of any other additive, which is confirmed by the fact that addition of polycationic additive, C1, caused coacervation in the heat-treated sample. As a result, concerns over effects of rock wettability or incompatibility with water treatment additives can be alleviated. No anionic FRs undergo similar change of the ionic charge. Thermal testing with cationic FR solutions also shows a significant viscosity drop, surprisingly without pronounced molecular weight loss (via MALLS). However, core flow testing of cationic FR fluids shows good regained permeability, even without breakers, further confirming self-cleaning capability. The degradation mechanism of these FRs will be shown. The self-cleaning capability of the dry cationic FR, even at relatively low bottomhole temperature (BHT), in combination with its high salt-tolerance, makes it an excellent friction reducer for multiple applications, especially with low quality water.

Flaw detection of tubural refractory products by the method of thermal testing

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Thermal and Flame Retardant Behavior of Neem and Banyan Fibers When Reinforced with a Bran Particulate Epoxy Hybrid Composite

Awareness of environmental concerns influences researchers to develop an alternative method of developing natural fiber composite materials, to reduce the consumption of synthetic fibers. This research attempted testing the neem (Azadirachta indica) fiber and the banyan (Ficus benghalensis) fiber at different weight fractions, under flame retardant and thermal testing, in the interest of manufacturing efficient products and parts in real-time applications. The hybrid composite consists of 25% fiber reinforcement, 70% matrix material, and 5% bran filler. Their thermal properties—short-term heat deflection, temperature, thermal conductivity, and thermal expansion—were used to quantify the effect of potential epoxy composites. Although natural composite materials are widely utilized, their uses are limited since many of them are combustible. As a result, there has been a lot of focus on making them flame resistant. The thermal analysis revealed the sample B was given 26% more short-term heat resistance when the presence of banyan fiber loading is maximum. The maximum heat deflection temperature occurred in sample A (104.5 °C) and sample B (99.2 °C), which shows a 36% greater thermal expansion compared with chopped neem fiber loading. In sample F, an increased chopped neem fiber weight fraction gave a 40% higher thermal conductivity, when compared to increasing the bidirectional banyan mat of this hybrid composite. The maximum flame retardant capacity occurred in samples A and B, with endurance up to 12.9 and 11.8 min during the flame test of the hybrid composites.

Thermal Testing and Analysis Techniques for Wires and Wire Bundles

Determining wire and wire bundle amperage capacity (i.e., “ampacity”) currently relies on the use of standards to derate wire ampacity when in a bundle configuration. The feasibility of developing physics-based and regression thermal models of single wires and wire bundles to determine ampacity using a customized test apparatus was investigated during a pathfinder study. A test facility was developed and various wire and wire bundle articles were tested under a variety of temperature and pressure conditions using an efficient test matrix formulated using Design of Experiments (DOE) techniques. Physics-based models were developed and correlated to the test results. Regression models were formulated and compared to test results and standards.

Методи діагностування дефектів деталей авіаційних двигунів з композиційних матеріалів

The key priority in improving the technical and economic performance of gas turbine engines lays in the use of new composite materials. The use of composites in the components of critical load-carrying structures operating under static and dynamic loads during long service lives determines the need to predict the component lives. Also, in order to increase the safety of engine operation and improve the parts manufacturing process, timely defect detection in such structures is of great importance. This article is devoted to the detection of the composite parts defects and damages that occur at different stages of manufacturing and operation. The aim is to investigate the existing methods of non-destructive testing of composite materials, describe their functional concept, and determine the field of their application. The article considers acoustic, thermal, optical, and radiation testing methods. Among the acoustic methods, the phased array method is selected as the most informative and multipurpose. The acoustic emission method is also selected; it will allow real-time monitoring of defect growth during testing. Out of thermal methods, the vibrothermography method was selected as the most advanced among the thermographic sub-methods. It allows using the phenomenon of local defect resonance and thus ensures effective defect detection. Shearography is selected for investigation out of optical methods. The special aspects of the use of X-ray methods are considered through the example of X-ray computed tomography. It is concluded that the approach combining several methods can significantly increase the efficiency of defect detecting and help to assess their criticality. Active thermal testing is well suited for fast scanning of large-sized parts and searching for areas of defect accumulation. In the following, local methods, such as impedance, vibrothermography, or one of the ultrasonic, should be used. To measure deformations under static load, it is a good practice to use shearography. To identify progressive defects under static load, it makes sense to use the acoustic emission method.

Теплофизические характеристики теплозащитного пакета корпуса ракетного двигателя при программированном нагреве

An experimental determination of the temperature dependences of the thermophysical characteristics of the MFP-92 multifunctional coating in the operating temperature range under thermal loading, simulating standard flight conditions, has been carried out. Heating was carried out with a jet of an industrial oxygen-propane burner mounted on a tripod with the possibility of varying the distance to the surface of the sample. The programs of the material operating modes include two peaks of heating to a temperature of ~1400 ° C with a heating and cooling rate of 20 - 40 deg / s. Under such conditions, thermal degradation of the MFP-92 material occurs, which changes its phase composition, structure, and, accordingly, thermophysical characteristics (TPС). The main transformations in the MFP-92 material occur in the temperature range up to 1000 °C, therefore, the heat transfer in it for given heating programs can be described using a simplified TРС model. This model assumes the existence of material in two states - initial (phase A) and annealed with completely completed transformation processes (phase B), each of which is assigned its own set of TPC. To determine the TPC of the MFP-92 material in its samples during thermal testing, temperature fields were recorded, which were then processed using the method of solving the inverse (coefficient) problem of thermal conductivity on a computer model. As a result, the temperature dependences of the specific heat and the coefficient of thermal conductivity of phases A and B were obtained, as well as the value of the most powerful thermal effect of the phase transition at 110 °C in phase A. The remaining phase transitions were taken into account by the corresponding changes in the specific heat. During material testing, the emissive of the material is also determined. Verification of the two-phase model of the MFP-92 material and the obtained values of its TPC was carried out based on the temperature fields obtained during the thermal tests of the samples of the three-layer thermal protection package "MFP-92 material-thermal insulation-steel substrate" under heating conditions according to the operating mode program confirmed their adequacy.