A SUSTAINABILITY APPROACH: INTEGRATION OF A MICROENCAPSULATED PHASE CHANGE MATERIAL TO A RECYCLED PES NONWOVEN FABRIC TO DEVELOP A HEAT STORING RECYCLED MATERIAL

Phase change materials (PCMs) are thermal energy storing materials which are adopted in various industries including textiles. They provide temperature regulation by absorbing the heat from the ambiance or releasing the latent heat that they store. PCMs are widely integrated into textiles in microencapsulated form where the core PCM is covered by the microcapsule shell and protected during phase change. This form also provides a higher thermal conductivity. In this work, a blend of organic coconut oil and n-octadecane were used as phase change material in core, and melamine formaldehyde was used as shell material to develop microencapsulated PCM for heat storage. The microcapsules were produced by using in situ polymerization method. The developed microcapsules (MPCMs) were integrated to a recycled PES (polyester) nonwoven fabric, generated from PET (polyethylene terephthalate) fibres, and manufactured by combing and needle punching technique. The MPCMs were implemented to the fabric by coating method. The core PCM, MPCM, and the coated nonwoven fabric were assessed by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). SEM results indicated that spherical and uniform microcapsules were obtained with a particle size of 3-9 μm. DSC results revealed that MPCM and the MPCM coated nonwoven fabric possessed a remarkable melting enthalpy of 111 J/g and 30.9 J/g, respectively at peak melting temperatures of 28.1°C and 27.4°C.

Особенности конструирования углерод-углеродных композитов фрикционного назначения, изготовленных аэродинамическим методом, на основе дискретных волокон

The designing of carbon-carbon composites (СCС) for friction use is an important problem, since the existing approaches are applicable only to technologies for obtaining materials using continuous fiber in the form of tapes and fabrics and are not suitable for products with chaotic reinforcement by short fibers, the use of which improves the mechanical characteristics of ССС both under static and dynamic influences. Also, this technology has economic advantages due to the use of cheaper raw materials and a significant reduction in the time of the molding stage in the presence of comparable physical, mechanical and frictional properties with CCC based on needle-punching and needle-piercing. To ensure the strength of discretely reinforced friction products, it is necessary to ensure the required effective length of the carbon fiber in the bundles distributed in the volume of the material, due to their evaluation by the degree of separation of the filaments. This article shows the dependence of the critical length of the bundle on the number of its fibers, from which it is found out that the critical length of the bundle sets the minimum threshold value at which the material is able to realize high strength characteristics. These ratios allow us to estimate the minimum necessary rate of separation of the bundle for a given fiber length. this will allow you to realize the maximum strength of the material, taking into account the technological limitations in the rate of separation. Models are also proposed that allow us to evaluate the technological prospects for the manufacture of discretely reinforced carbon-carbon materials for friction purposes and to predict their properties. The effect of additional reinforcement of the inter-joint spaces of the composite material on its wear resistance at high specific friction energies is shown

Development of Needle-Punched Nonwoven Fabrics from Natural Fibers for Sound Absorption Behavior

: The natural fibers prepared from plant waste have parameters like fiber strength, length, and chemical composition which are suitable to fabric and the fibers into nonwoven. The selected plants were identified from their botanical names by comparing the collected samples with those of known identity in the herbarium of a botanical survey in India with their names as Sesbania grandiflora, Mutingia Calabura, and Bauhinia Purpurea. A novel Portable multi-fibre decorticator machine was fabricated and used to extract the fibers from the plant stem and barks. The extracted fibers are done physical characterization and their properties are investigated. The extracted fibers are blended with other natural fibers like jute and flax in appropriate proportions 45:45:10 and nonwoven fabrics were prepared by the needle-punching method. Three and four-layer nonwovens are produced using a needle punching machine. The developed nonwovens are tested using standard apparatus and the effect of natural fibers in areal density, thickness; bulk density, porosity, and air permeability are analyzed. In addition, thermal conductivity and sound absorption behaviour are also investigated. The sound absorption property increases concerning areal density and fabric thickness. The thermal conductivity increased by increasing the fiber layer in the fabric to evaluate its potential as a protective barrier material in non-woven face masks.

Influence of Needle-punching Parameters for the Preparation of Polypyrrole-coated Non-woven Composites for Heat Generation

This work deals with the preparation and characterization of electrically conductive needle-punched non-wo¬ven composites for heat generation. Electro-conductive non-woven composites were prepared through the in situ chemical polymerization of pyrrole with FeCl3 (oxidant) and p-toluene sulfonic acid (dopant). A two-stage double-bath process was adopted for the in situ chemical polymerization of pyrrole. The effect of parameters such as fibre fineness, needle-punching density and depth of needle punching on a polypyrrole add-on, and surface resistivity were studied by employing the Box-Behnken response surface design. It was observed that fibre fineness was the most influential parameter of the polypyrrole add-on. The lowest surface resistivity of the polypyrrole coated sample (200 g/m2, prepared with a punch density of 200 punch/cm2, a punching depth of 6 mm and fibre fineness of 2.78 dtex) was found to be 9.32 kΩ/ with a polypyrrole add-on of 47.93%. This non-woven composite demonstrated good electrical conductivity and exhibited Joule’s effect of heat gener¬ation. Due to the application of a 30 V DC power supply, the surface temperature of the non-woven composite rose to 55 °C from a room temperature of 37 °C. Optical and electron microscopy images of the non-woven composites showed that PPy molecules formed a uniform coating on the non-woven surface. FTIR studies evi¬denced the coating of PPy on a polyester surface. These coated non-woven composites were highly electrically conductive and practically useful for the fabrication of heating pads for therapeutic use.

3D Thermal Network Supported by CF Felt for Improving the Thermal Performance of CF/C/Epoxy Composites

The heat generated by a high-power device will seriously affect the operating efficiency and service life of electronic devices, which greatly limits the development of the microelectronic industry. Carbon fiber (CF) materials with excellent thermal conductivity have been favored by scientific researchers. In this paper, CF/carbon felt (CF/C felt) was fabricated by CF and phenolic resin using the “airflow network method”, “needle-punching method” and “graphitization process method”. Then, the CF/C/Epoxy composites (CF/C/EP) were prepared by the CF/C felt and epoxy resin using the “liquid phase impregnation method” and “compression molding method”. The results show that the CF/C felt has a 3D network structure, which is very conducive to improving the thermal conductivity of the CF/C/EP composite. The thermal conductivity of the CF/C/EP composite reaches 3.39 W/mK with 31.2 wt% CF/C, which is about 17 times of that of pure epoxy.

Force kinematic analysis of the process of needle punching of woven preforms

Описан процесс трансверсального армирования плетеных преформ иглопробивкой. Определен процесс взаимодействия иглы с оплеточными жгутами с учетом деформационных процессов изменения амплитуды переплетения и проскальзыванием жгутов плетеной структуры материала при введении иглы. Приведены экспериментальные данные сопротивления проникновению иглы в преформу и подложку. The process of transverse reinforcement of woven preforms with needle punching is described. The process of interaction of the needle with the braiding cords is determined, taking into account the deformation processes of the change in the weave amplitude and the slippage of the cords of the woven structure of the material when the needle is inserted. Experimental data on resistance to penetration of the needle into the preform and substrate are presented.