Sandwich Fibrous PEG Encapsulations for Thermal Energy Storage.

Phase change materials (PCMs) textiles have been developed for personal thermal management (PTM) while limited loading amount of PCMs in textiles reduced thermal buffering effect. In this work, we proposed a sandwich fibrous encapsulation to store polyethylene glycol (PEG) with PEG loading amount of 45 wt %, which consisted of polyester (PET) fabrics with hydrophobic coating as protection layers, polyurethane (PU) nanofibrous membranes as barrier layers and PEG-loaded viscose fabric as a PCM-loaded layer. The leakage was totally avoided by controlling weak interfacial adhesion between protection layer and melting PEG. The sandwich fibrous PEG encapsulations had an overall melting enthalpy value ranging from 50 J/g to 78 J/g and melting points ranging from 20 °C to 63 °C by using different PEGs. Besides, introduction of Fe microparticles in PCM-loaded layer enhanced thermal energy storage efficiency. We believe that the sandwich fibrous PEG encapsulation has a great potential in various fields.

Structural Analysis of Phase Change Materials (PCMs)/Expanded Graphite (EG) Composites and Their Thermal Behavior under Hot and Humid Conditions.

Expanded graphite (EG) has been used to store phase change materials (PCM) to enhance thermal conductivity and avoid leakage. However, systematic investigation on physical structure of various embedded PCMs in EG is not reported. Besides, the effect of environment on thermal behavior of PCM/EG composites has not been investigated yet. In this work, three common PCMs (including myristic acid (MA), polyethylene glycol (PEG) and paraffin wax (PW)) were embedded in EG and three PCM/EG composites were obtained. As a result, capillary force between EG and PCMs supported encapsulation of PCMs in EG. PCM/EG composites had narrower phase change range while supercooling degree values were different when various PCMs were used. Besides, the hot and humid environment had a side effect on thermal energy storage of PCMs and PCM/EG composites. The inherent hydrophilicity of PCMs was essential for resistance against side effect of moisture on thermal energy storage.

Incorporation of Cellulose-Based Aerogels into Textile Structures.

Given their exceptional attributes, aerogels are viewed as a material with immense potential. Being a natural polymer, cellulose offers the advantage of being both replenishable and capable of breaking down naturally. Cellulose-derived aerogels encompass the replenish ability, biocompatible nature, and ability to degrade naturally inherent in cellulose, along with additional benefits like minimal weight, extensive porosity, and expansive specific surface area. Even with increasing appreciation and acceptance, the undiscovered possibilities of aerogels within the textiles sphere continue to be predominantly uninvestigated. In this context, we outline the latest advancements in the study of cellulose aerogels' formulation and their diverse impacts on textile formations. Drawing from the latest studies, we reviewed the materials used for the creation of various kinds of cellulose-focused aerogels and their properties, analytical techniques, and multiple functionalities in relation to textiles. This comprehensive analysis extensively covers the diverse strategies employed to enhance the multifunctionality of cellulose-based aerogels in the textiles industry. Additionally, we focused on the global market size of bio-derivative aerogels, companies in the industry producing goods, and prospects moving forward.

Effects of ultrasonic-assisted nickel pretreatment method on electroless copper plating over graphene.

In this paper, copper deposited graphene was fabricated through electroless plating. A novel and facile pretreatment method is introduced based on ultrasonic treatment with nickel nano-particles as the catalytic core. This method abandons the sensitization and activation process in the traditional pretreatment that reduces the time and economic cost dramatically. The static contact angle was determined by an Olympus BX51M optical microscope. The surface morphology and plating composition were characterized via scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), the infrared radiation (IR) transmittance spectra of the copper plated graphene were measured by Fourier transform infrared spectroscopy (FTIR), the layer structure was measured by Raman spectrum, the phase identification was identified by X-ray diffraction (XRD), the thermogravimetric analysis (TGA) (Q5000 TA instruments, USA) was carried out to detect the thermal characteristics. The electrical resistivity of copper-plated graphene was performed in an especially designed apparatus. The results show that the surface of graphene is coarsened, and the size is reduced after ultrasonic treatment, which can facilitate the nucleation and fine particle distribution of metal. The electroless plated efficiency of copper of the nickel pretreatment copper-plated graphene is 64.27 wt%, higher than that of generic copper-plated graphene at 58.62 wt%. The resistivity decreases rapidly from 1.69 × 10-2 Ω cm of the original Gr to 0.79 × 10-2 Ω cm of Cu/Ni@Gr due to the large number of fine copper particles scattered around the graphene.

The Effect of Mask Style and Fabric Selection on the Comfort Properties of Fabric Masks.

The purpose of fabric masks in the prevention of the spread of COVID-19 often requires that the masks be worn for extended periods without removal. The management of the conditions in the micro-climate inside the masks is important to keep the wearer comfortable and enhance user compliance. In this study, the effect of mask design and fabric type on the micro-climate was investigated using thermocron iButtons to record the temperature and humidity inside the masks. It was found that the mask style, and its effect on the amount of air incorporated in the micro-climate, had a significant influence on the factors that determine the temperature and humidity levels. In the shaped masks, the impact of the mask design on the results was stronger than the effect of fabric type. In the folded masks that fit snugly around the face, the effect of fabric type was significant, and both fibre composition and fabric structure contributed to the differences in the performance of the three fabrics tested. In the case of the masks with an inserted filter, a significant amount of trapped still air in the fabric layers and the increased mask stiffness had the strongest effect on the temperature and humidity inside the masks. Significant differences were also found in the temperatures recorded in the different time segments, highlighting the importance of conducting comfort evaluations over a long enough time to prevent false interpretations. The results of this study emphasize the importance of considering all the components of mask design, namely style, fibre type, and fabric structure, in the development of masks to enhance user compliance.

Hybrid Prepreg Tapes for Composite Manufacturing: A Case Study.

The aim of this research was the preparation and characterization of hybrid prepreg tapes from glass multifilament roving (circular cross-section). The fiber, roving, and tape strength distribution was characterized by exploratory data analysis tools (especially quantile-quantile plot) and modeled by the three parameters' Weibull distribution. For estimation of Weibull model parameters, the noniterative technique based on the so-called Weibull moments was used. It was shown that the prepared hybrid prepreg tapes prepared by controlled mechanical spreading technology developed by the authors improved mechanical tensile properties and can be used for the preparation of composites of complicated forms by robotic winding.

Unmasking the Mask: Investigating the Role of Physical Properties in the Efficacy of Fabric Masks to Prevent the Spread of the COVID-19 Virus.

To function as source control, a fabric mask must be able to filter micro-droplets (≥5 µm) in expiratory secretions and still allow the wearer to breathe normally. This study investigated the effects of fabric structural properties on the filtration efficiency (FE) and air permeability (AP) of a range of textile fabrics, using a new method to measure the filtration of particles in the described conditions. The FE improved significantly when the number of layers increased. The FE of the woven fabrics was generally higher, but double-layer weft knitted fabrics, especially when combined with a third (filter) layer, provided a comparable FE without compromising on breathability. This also confirmed the potential of nonwoven fabrics as filter layers in masks. None of the physical fabric properties studied affected FE significantly more than the others. The variance in results achieved within the sample groups show that the overall performance properties of each textile fabric are a product of its combined physical or structural properties, and assumptions that fabrics which appear to be similar will exhibit the same performance properties cannot be made. The combination of layers of fabric in the design of a mask further contributes to the product performance.

Sandwich Structures Reflecting Thermal Radiation Produced by the Human Body.

Far infrared (FIR) textiles are a new category of functional textiles that have presumptive health and well-being functionality and are closely related to human thermo-physiological comfort. FIR exerts strong rotational and vibrational effects at the molecular level, with the potential to be biologically beneficial. In general, after absorbing either sunlight or heat from the human body, FIR textiles are designed to transform the energy into FIR radiation with a wavelength of 4-14 µm and pass it back to the human body. FIR textiles can meet increased demand for light, warm, comfortable, and healthy clothing. The main aim of this research is to describe the procedure for creating the FIR reflective textile layer as part of multilayer textile structures that have enhanced thermal protection. To develop the active FIR reflecting surface, the deposition of copper nanolayer on lightweight polyester nonwoven structure Milife, which has beneficial properties of low fiber diameters, good shape stability and comfort, was used. This FIR reflective layer was used as an active component of sandwiches composed of the outer layer, insulation layer, active layer, and inner layer. The suitable types of individual layers were based on their morphology, air permeability, spectral characteristics in the infra-red region, and thermal properties. Reflectivity, transmittance, and emissivity were evaluated from IR measurements. Human skin thermal behavior and the prediction of radiation from the human body dependent on ambient conditions and metabolic rate are also mentioned. The FIR reflective textile layer created, as part of multilayer textile structures, was observed to have enhanced thermal protection.

A Review of Impact of Textile Research on Protective Face Masks.

COVID-19, classified as SARS-CoV-2, is causing an ongoing global pandemic. The pandemic has resulted in the loss of lives and has caused economic hardships. Most of the devices used to protect against the transmission of the novel COVID-19 disease are related to textile structures. Hence, the challenge for textile professionals is to design and develop suitable textile structures with multiple functionalities for capturing viruses, passivating them, and, at the same time, having no adverse effects on humans during the complete period of use. In addition to manufacturing efficient, biocompatible, and cost-effective protective face masks, it is also necessary to inform the public about the benefits and risks of protective face mask materials. The purpose of this article is to address the concerns of efficiency and efficacy of face masks by primarily reviewing the literature of research conducted at the Technical University of Liberec. The main focus is on the presentation of problems related to the specification of aims of face mask applications, mechanisms of capture, durability, and modes of sterilization. The recommendations, instead of conclusions, are addressed to the whole textile society because they should be leading players in the design, creation, and proper treatment of face masks due to their familiarity with the complex behavior of textile structures and targeted changes of structural hierarchy starting from polymeric chains (nano-level) and ending in planar textile structures (millimeter level) due to action by mechanical, physical and chemical fields. This becomes extremely critical to saving hundreds of thousands of lives from COVID-19.

Electromagnetic Interference Shielding of Metal Coated Ultrathin Nonwoven Fabrics and Their Factorial Design.

Electromagnetic (EM) radiation is everywhere in this world and galaxy in different forms and levels. In some cases, human beings need to protect themselves from electromagnetic radiations and the same thing is also recommended for electronic devices as well. Lots of studies are there on the shielding of electromagnetic radiation interference using metals, polymers, and minerals. For protecting the human being, textile structures are playing the main role. In the textile material structure itself many types are there; each one is having its unique geometrical shape and design. In this work, the copper/nickel-coated ultrathin nonwoven fabric is prepared like a strip. The 3, 6, and 9 mm thick strips are prepared and laid at different gaps, angles, and layered to study the effect of factors on EM shielding effectiveness as per ASTM D4935-10 standard. The design of experiment has been done to analyze the three factors and three levels of the strip properties having an influence on electromagnetic shielding results. From the findings of the design of experiment (DoE) screening design, the factors are the thickness of the strips, the gap between the strips, and the strips laid angle having a statistically significant effect on electromagnetic shielding effectiveness.

Preparation and Characterization of Electrosprayed Aerogel/Polytetrafluoroethylene Microporous Materials.

This paper presents the preparation of aerogel/polytetrafluoroethylene (PTFE) microporous materials via needleless electrospray technique, by using an aqueous dispersion of polytetrafluoroethylene as the basic spinning liquid. Different contents of aerogel powders were applied to the spinning liquid for electrospraying to investigate the effect on the structural characteristics and various properties of the materials. Cross-section, surface morphology, and particle size distribution of the electrosprayed materials were examined. Surface roughness, hydrophobicity, and thermal conductivity were evaluated and discussed. The results showed that the electrosprayed aerogel/PTFE layers were compact and disordered stacking structures composed of spherical particles with a rough surface. As the aerogel content increased, the electrosprayed materials demonstrated increased surface roughness and improved surface hydrophobicity with a contact angle up to 147.88°. In addition, the successful achievement of thermal conductivity as low as 0.024 (W m-1 K-1) indicated a superior ability of the prepared aerogel/PTFE composites to prevent heat transfer. This study contributes to the field of development of aerogel/PTFE composites via electrospray technique, providing enhanced final performance for potential use as thermal and moisture barriers in textiles or electronic devices.

Transport Properties of Electro-Sprayed Polytetrafluoroethylene Fibrous Layer Filled with Aerogels/Phase Change Materials.

This work is the first attempt to prepare microporous polytetrafluoroethylene (PTFE) fibrous layers embedded with aerogels/phase change materials. For preparation of this layer, the needle-less electrospray technology of water dispersion of individual components is used. Microstructure characteristics, including surface morphology and particle size distribution, and various properties of the prepared materials were investigated and explained. Transport performance of the fibrous layers embedded with aerogels/phase change materials, such as the transmission of heat, air, and water vapor was evaluated and discussed in details. It was found that the electro-sprayed materials composed by spherical particles with rough surface had compact disordered stacking structure. Aerogels and phase change materials (PCMs) play different roles in determining structural parameters and transport properties of the materials. Those parameters and properties could be flexibly adjusted by optimizing the spinning parameters, changing the content or proportion of the fillers to meet specific requirements.

Resistance against Penetration of Electromagnetic Radiation for Ultra-light Cu/Ni-Coated Polyester Fibrous Materials.

Resistance against penetration of various rays including electromagnetic waves (EM), infrared rays (IR), and ultraviolet rays (UV) has been realized by using copper (Cu)-coated fabrics. However, the corrosion of the Cu on coated fabrics influenced the shielding effectiveness of the various rays. Besides, the metal-coated fabrics have high density and are unbreathable. This work aims to solve the problem by incorporating nickel (Ni) into the Cu coating on the ultra-light polyester fibrous materials (Milife® composite nonwoven fabric-10 g/m2, abbreviation Milife) via electroless plating. The electromagnetic interference (EMI), IR test, ultraviolet protection factor (UPF), water contact angle, and air permeability of the Cu/Ni-coated Milife fabric were measured. All the samples were assumed as ultra-light and breathable by obtaining the similar fabric density (~10.57 g/m2) and large air permeability (600-1050 mm/s). The Cu/Ni deposition on the Milife fabrics only covered the fibers. The EM shielding effectiveness (SE) decreased from 26 to 20 dB, the IR reflectance (Rinfrared) decreased from 0.570 to 0.473 with increasing wNi from 0 to 19.5 wt %, while the wNi improved the UPF from 9 to 48. Besides, addition of Ni changed the Cu/Ni-coated Milife fabric from hydrophilicity to the hydrophobicity by observing WCA from 77.7° to 114°.

Preparation of Electrosprayed, Microporous Particle Filled Layers.

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer known for its excellent hydrophobic properties. In this work, samples from PTFE dispersions with different combinations of water and carbon microparticles were prepared using an electrospraying method. The morphologies and sizes of carbon particles were investigated and the properties of layers including roughness, hydrophobicity and electrical resistivity were investigated. The non-conductive carbon microparticles were selected as a model particle to check the compatibility and electrospraying ability, and it had no effect on the hydrophobic and electrical properties. Carbon microparticles in polymer solution increased the degree of ionization and was found to be beneficial for the shape control of materials. The results showed that PTFE dispersion with the composition of water and carbon microparticles produced fine sphere particles and the layer fabricated with increased roughness. It was also found that the electrical resistivity and hydrophobicity of all the layers comparatively increased. The fabricated microporous layers can be used in various applications like interlining layer in multilayer textile sandwiches.

Influence of Nanoparticles on Thermal and Electrical Conductivity of Composites.

This review analyzes thermal and electrically conductive properties of composites and how they can be influenced by the addition of special nanoparticles. Composite functional characteristics-such as thermal and electrical conductivity, phase changes, dimensional stability, magnetization, and modulus increase-are tuned by selecting suitable nanoparticle filler material. The conductivity of composites can be related to the formation of conductive pathways as nanofiller materials form connections in the bulk of a composite matrix. With increasing use of nanomaterial containing composites and relatively little understanding of the toxicological effects thereof, adequate disposal and recyclability have become an increasing environmental concern.

Progress in Sol-Gel Technology for the Coatings of Fabrics.

The commercial availability of inorganic/organic precursors for sol-gel formulations is very high and increases day by day. In textile applications, the precursor-synthesized sol-gels along with functional chemicals can be deposited onto textile fabrics in one step by rolling, padding, dip-coating, spraying or spin coating. By using this technology, it is possible to provide fabrics with functional/multi-functional characteristics including flame retardant, anti-mosquito, water- repellent, oil-repellent, anti-bacterial, anti-wrinkle, ultraviolet (UV) protection and self-cleaning properties. These surface properties are discussed, describing the history, basic chemistry, factors affecting the sol-gel synthesis, progress in sol-gel technology along with various parameters controlling sol-gel technology. Additionally, this review deals with the recent progress of sol-gel technology in textiles in addressing fabric finishing, water repellent textiles, oil/water separation, flame retardant, UV protection and self-cleaning, self-sterilizing, wrinkle resistance, heat storage, photochromic and thermochromic color changes and the improvement of the durability and wear resistance properties.