Adam Puszkarz

Simulations of Heat Transport Phenomena in a Three-Dimensional Model of Knitted Fabric

Abstract The main goal of the current work is to analyse the three-dimensional approach for modelling knitted fabric structures for future analysis of physical properties and thermal phenomena. The introduced model assumes some simplification of morphology. First, fibres in knitted fabrics are described as monofilaments characterized by isotropic thermal properties. The current form of the considered knitted fabric is determined by morphological properties of the used monofilament and simplification of the stitch shape. This simplification was based on a particular technology for the knitting process that introduces both geometric parameters and physical material properties. Detailed descriptions of heat transfer phenomena can also be considered. A sensitivity analysis of the temperature field with respect to selected structural parameters was also performed.

The study of knitted fabric thermal insulation using thermography and finite volume method

The article concerns the widespread issue of thermal comfort; investigations into textiles and thermal insulation problems are presented. Materials that were tested include double-layer knitted fabrics with potential application in multi-layer garments addressed to a specific group of users. The investigated materials were constructed with the following raw materials: cotton, polypropylene, polyester, polyamide, bamboo, and viscose. The textiles with a comparable geometric structure and different composition were tested for their thermal insulation. In the experimental section the temperature gradients in specific constant ambient conditions using a thermal imaging camera were obtained. In the simulation section three-dimensional models of actual textiles were designed and the temperature gradients on the basis of performed simulations were calculated. Both measurements and simulations yielded comparable results and showed that the comparatively thick knitted fabrics’ thermal insulation strongly depends on the raw materials from which they were made and less on the parameters of the yarn.

Effect of Accelerated Ageing on Ballistic Textiles Modified By Plasma-Assisted Chemical Vapour Deposition (PACVD)

The functionalisation of textile products and materials using the low temperature plasma technique is increasingly used in industrial practice, mainly because of the many benefits, often unattainable with the use of other techniques. The study focused on the modification of the composite textile materials - sheets of Ultra High Molecular Weight Polyethylene (UHMWPE) fibres (Dyneema ® SB51) by applying the surface deposition of silicone-like polymer in an environment of low temperature plasma. The aim of this study was to evaluate changes in the mechanical and physical properties of modified ballistic textiles un der simulated storage conditions in accelerated time. Based on experiences in planning the research on accelerated aging, a test programme was developed for the assessment of changes during the aging process in ballistic fibrous materials under various environmen tal conditions. The process of low temperature plasma modification affected the mechani cal properties of the ballistic composite textile materials during the accelerated ageing using temperature or temperature and humidity. The effect of the modification varied with the mechanical properties investigated.

The surface modification of ballistic textiles using plasma-assisted chemical vapor deposition (PACVD)

This paper describes studies on the surface modification of so-called ballistic materials (materials commonly used to protect the human body against firearms, i.e. fragments or bullets). Two materials, an ultra-high molecular weight polyethylene (UHMWPE) composite and aramid fabric, were investigated. The surfaces of these fibrous materials were modified using plasma-assisted chemical vapor deposition (PACVD) to examine the effects of the modification on the material properties, which are important for designing ballistic protections. Accordingly, both the mechanical strength and water resistance of the modified materials were tested. The results clearly show the impact of the modification on both parameters.

Study of Multilayer Clothing Thermal Insulation Using Thermography and the Finite Volume Method

The article concerns the wide issue which is thermal comfort. In the paper investigations on the textile thermal insulation problem are presented. Materials tested were multi-layer systems with potential application in uniforms addressed to firefighters. Thermal insulation was tested both experimentally (using a thermal imaging camera) and by modelling (by means of simulations of heat transfer phenomena on 3-D models of real textiles). The materials investigated were constructed with the following raw materials: Kevlar, Nomex, ePTFE, PU and carbon fiber. Textiles with a comparable geometric structure and similar composition were tested for their thermal insulation. In the experimental part temperature, the change in specific constant ambient conditions was obtained using a thermal imaging camera. In the simulation part 3-D models of actual textiles were designed and the temperature change was calculated on the basis simulations of the real experiment performed . For each multi-layer system two models were designed, with varying degree of mapping the structure of the yarn in the fabrics. The main goal of the work was experimental verification of both models. As a result of the simulation performed on a model characterised by a more accurate mapping of the yarn structure, comparable results were obtained with experimental data and a strong relationship of thermal insulation textiles from the composition of raw materials and the geometric structure was confirmed.

Structural Changes in Fibrous Ballistic Materials During PACVD Modification

During PACVD Modification. FIBRES & TEXTILES in Eastern Europe 2015; 23, 6(114): 102-115. DOI: 10.5604/12303666.1167426 102 Researches focused on improving the adhesion of UHMWPE fibres with resin or low-molecular polyethylene forming the destination matrix of the final ballistic material, inter alia by increasing the surface energy. This enables better and more durable blending of modified fibres with the matrix material [4 12]. The effect of plasma assisted chemical vapour deposition (PACVD) polymer deposition onto textile ballistic materials on the physicalmechanical behaviour was described in detail in [4, 13]. ,5,6,7,8,9,10,11,12 The aim of the research was to optimise PACVD modification of two types of unpurified technical textile materials: p-aramid fabric and UHMPWE fibrous materials, to directly obtain a functionalized surface with a highly reproductive deposited polymer.

Modeling of Air Permeability of Knitted Fabric Using the Computational Fluid Dynamics

Abstract This article concerns the widespread matter of biophysical comfort. In this work, 10 double-layer knitted fabrics with potential application in multilayer garments addressed to a specific group of users, such as newborns, were investigated. The materials were constructed with the following raw materials: cotton, polypropylene, polyester, polyamide, bamboo, and viscose. The textiles with a comparable geometrical structure and different composition were tested for their air permeability. In the experimental part, the materials were tested in specific constant ambient conditions using an air permeability tester. In the simulation part, 3D models of actual textiles were designed and air permeability based on the performed simulations using finite volume method was calculated. Both measurements and simulations yielded comparable results and showed that the air permeability of the knitted fabric strongly depends on the thickness and geometrical parameters of yarn.

Structural Changes in the PACVD -Modified Para-Aramid, Ballistic Textiles During the Accelerated Ageing

The process of textile modification using Plasma Assisted Chemical Vapour Deposition (PACVD) results in significant changes in surface properties with high effectivity. However, the main problem of the above-mentioned modification is to obtain a stable modification effect during standard use and storage. The aim of the study was to determine the stability of structural properties of PACVD-modified para-aramid ballistic woven fabrics during accelerated ageing using temperature or simultaneously temperature and humidity as the accelerated ageing factors. For identification of potential changes in the textile surface modified by PACVD with deposition of the polymer formed based on tetradecafluorohexane, the ATR-FTIR and SEM/EDS techniques were applied. The PACVD-modified textiles showed insignificant changes in structural properties after accelerated ageing using the above-mentioned ageing factors. This confirms the stability of the PACVD-resulted modification during simulated conditions of standard use.

Structural Changes in Plasma Assisted Chemical Vapour Deposition-Modified Ultra-high Molecular Weight Polyethylene, Ballistic Textiles During Accelerated Ageing

The aim of this study was to compare the susceptibility of the plasma assisted chemical vapour deposition (PACVD) surface modification of ultra-high molecular weight polyethylene (UHMWPE) fibrous composite to conditions of use and storing simulated by accelerated aging. Aspects of heksametylodisiloksan (HMDSO) implementation as donor for deposited during PACVD modification nanolayer as well as the selection of a new textile carrier were discussed. For the identification of potential changes in PACVD modified UHMWPE, with, the Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) and Scanning Electron Microscopy with X-ray microanalysis (SEM/EDS) techniques were applied. The PACVD surface modification of UHMWPE showed insignificant changes in structural properties after using temperature or simultaneously temperature and humidity ageing factors. The process of accelerated ageing confirmed the time-stable presence of silicon contained in the polymer layer in both cases: when temperature or simultaneously temperature and humidity were used as accelerated aging factors. No significant changes in the morphology nor topography of the fibrous materials tested were found, subjected or not to the process of PACVD modification using the HMDSO as a substrate for the surfacedeposited polymer.

Performance Stability of Ballistic Para-Aramid Woven Fabrics Modified by Plasma-Assisted Chemical Vapour Deposition (PACVD)

Plasma-assisted chemical vapour deposition (PACVD) is often used for the modification of the surface properties of a wide range of materials. The resulting effect of PACVD modification considerably changes the behaviour of the material. The process of surface modification by PACVD of a textile is significantly complex due to the topography resulting in the fabric structure. Taking ecology and economy into account, PACVD modification is more efficient as compared with traditional finishing processes. However, the stability of the PACVD effect gets lost during usage of the textile under standard conditions. The aim of the research was to verify in an enhanced accelerated ageing test the stability of PACVD modification of para-aramid woven fabrics applied for designing of soft ballistic inserts in body protectors. The simulated ageing yielded a significant change in the mechanical properties of non-modified textiles, whereas PACVD-modified samples showed prolonged stability of the properties obtained.