Rui Miguel

Abrasion Kinetics of Wool and Blended Fabrics

The abrasion resistance of different wool and blended fabrics is measured with the Martindale wear and abrasion tester, the abrasion kinetics is identified by the shape of the mass loss curve versus abrasion cycles up to yarn breakage. A concave kinetic curve shows a low initial weight loss rate, which continues to increase throughout the process up to the end. A convex kinetic curve begins with a high initial weight loss rate, which continues to decrease throughout the process. The third kinetic curve shows an almost linear relationship between mass loss and abrasion cycles up to yarn breakage. Due to the long time required for the abrasion test to yarn breakage, a simplified method is used based on the determination of mass loss up to 5000 abrasion cycles. The initial mass loss rate and the mean value of this rate throughout the 5000 abrasion cycles (i.e., the mean abrasion gradient) seem to be good estimates of the surface and structural abrasion degradation of the fabrics, and they show a strong relationship with the structural parameters of the fabrics.

Optical Estimation of a Set of Pilling Coefficients for Textile Fabrics

This paper presents the results obtained using an experimental system, based on optical triangulation, which enabled topographic reconstructions of textile fabric surfaces. Consequently, one could evaluate and quantify the pilling formation through the optical estimation of a set of pilling coefficients. The proposed method was found to be precise, robust and systematic, and may constitute an alternative and/or complementary approach to quantify the pilling formation.

Virtual subjective pilling evaluation: an alternative

This paper reports an alternative approach for the evaluation of fabric pilling. On this approach, orthogonal projections of the three-dimensional (3D) fabric images are used directly to virtually evaluate the pilling formation of the fabrics. The 3D images of the fabrics are obtained through the reconstruction of the topography of the real textile fabrics. For that, a dual-scanning optical system (triangulation system) was used, which was developed and implemented by our research team. This evaluation approach is performed by comparing the appearance of the orthogonal projections of the 3D fabric images with the same photographic standard sets used in the conventional subjective method. For the validation of the obtained results with this methodology, a comparison was carried out relative to a reference subjective evaluation. This reference evaluation corresponds to a subjective evaluation of the fabrics originally performed by a panel of experts. A comparison was also performed between the results obtained with this methodology and those obtained by an objective evaluation. This objective evaluation corresponds to the automatic attribution of the equivalent pilling grade to the fabrics, based on the calculation of the total volume of pilling formed in their surfaces. The final results obtained with the described methodology were showed to be globally in agreement with both the reference subjective and the objective evaluations. Subsequently, this method shows potential as an alternative approach for the virtual subjective evaluation of fabric pilling.This paper reports an alternative approach for the evaluation of fabric pilling. On this approach, orthogonal projections of the three-dimensional (3D) fabric images are used directly to virtually evaluate the pilling formation of the fabrics. The 3D images of the fabrics are obtained through the reconstruction of the topography of the real textile fabrics. For that, a dual-scanning optical system (triangulation system) was used, which was developed and implemented by our research team.This evaluation approach is performed by comparing the appearance of the orthogonal projections of the 3D fabric images with the same photographic standard sets used in the conventional subjective method.For the validation of the obtained results with this methodology, a comparison was carried out relative to a reference subjective evaluation. This reference evaluation corresponds to a subjective evaluation of the fabrics originally performed by a panel of experts. A comparison was also performed between the results obtaine...

Synthesis of poly(3, 4-ethylenedioxythiophene) coating on textiles by the vapor phase polymerization method

In this article, plain weave fabrics of polyester were functionalized by means of a polymeric coating synthesized for high conductivity, using the vapor phase polymerization method. The method is considerably more efficient and sustainable than traditional wet methods and has been previously applied to synthesize poly(3, 4-ethylenedioxythiophene) in yarns and fabrics, using oxidant agents with organic solvents. In this article, aqueous oxidant solutions were used in addition to those based in ethanol, providing textile substrates with high electrical conductance. The effect of the concentration of the oxidant solution on the electrical and mechanical characteristics of the samples was investigated and correlated to their morphology, analyzed by electron microscopy imaging. A strong decrease of the sheet resistivity of the samples with the concentration of oxidant increase was obtained, while the fabrics’ original mechanical tenacity remained unchanged. The sheet resistivity of the samples could be further decreased by a factor of 5 by the application of multiple polymerization layers and was a function of the conjugated polymer content. The effect of washing/drying cycles on the electrical conductance of the samples is presented. The electrical and mechanical characteristics obtained have potential for smart textile applications such as electromagnetic shielding and physiological sensing.

Subjective and Objective Pilling Evaluations of Textile Fabrics: A Comparison

This paper addresses a comparison between three different approaches used to evaluate a set of different textile fabric samples in terms of pilling formation. Originally, the set was subjectively evaluated by a panel of experts, being that, our reference evaluation. Then, the same set of fabrics was analysed by a dual-scanning optical system which has been implemented by our team to reconstruct 3D images of the topography of the fabrics. With the obtained range data, an objective evaluation of the pilling formation was carried out based on the total pilling volume and the results showed to be in agreement with the original subjective evaluation. In this paper, our purpose is to establish a correspondence model in order to automatically attribute the equivalent pilling grade. Furthermore, the same set of fabrics was then subjectively reevaluated by different observers for comparison with the reference evaluation, and the results obtained by the correspondence model.

Garment abrasion strength evaluation: a comparative methods study

Purpose – The breaking strength compromises fabric wearing out during wear of garments and is a determining parameter in their useful life. Thus, it is intended to compare the efficacy of each method concerning the understanding of results, which is, the explanation of the phenomenon, namely through statistical models which characterize abrasion strength, measured by each method, as a function of fabric assurance by simple testing (FAST) parameters.Design/methodology/approach – The simulation of abrasion mechanism was done on Martindale wear and abrasion tester, following two ways: the weight loss and two yarns breakage methods. The average weight loss of a fabric was determined among four specimens (in mg/5,000 cy). Fabric abrasion was done against a standard wool fabric under a 12 KPa pressure. In the two yarns breakage method, the number of abrasion cycles required to break two yarns is determined according to Woolmark Company TM 112 test standard.Findings – In general, no better models to explain abra...

Fabric design considering the optimisation of seam slippage

Purpose – The dependence of seam slippage values on fabric construction parameters makes this property an interesting case for study.Design/methodology/approach – In this study, made on a significant wool and blended fabrics sample, the seam slippage was measured, either in warp direction (weft yarns slip), or in weft direction (warp yarns slip), using a specially equipped load‐elongation tester. Testing was done following the TM 117 Woolmark Company test method.Findings – For most fabrics, the conventional variables that impact seam slippage most seriously are opacity, polyamide content, finish type and cover factor.Research limitations/implications – Since this research does not deal with the variable of yarn crimp in fabrics, it is the cover factor that plays the central role, as the property determining seam slippage. The yarns with lower cover factor (less crimped) are in less danger of slipping between the perpendicular yarns (more crimped) and vice versa.Practical implications – Based on the equati...

Texturing, Stretching and Relaxation Behaviour of Polylactide Multifilament Yarns

Polylactide multifilament yarns were textured in order to be endowed with properties of natural staple fibre yarns for textile applications. Texturing promotes the formation of stable secondary links between the macromolecular chains. A polylactide 167/68 dtex multifilament yarn was textured under different conditions. Relaxation experiments at yield, strain softening, strain hardening and just before breaking were performed. The relaxation behaviour was studied by the application of the generalized Maxwell model. The initial stress induced when stretched, the final non-relaxed stress after relaxation and the stress relaxed at different times were determined. Variations in the relaxation behaviour were related to texturing conditions and stretching.

Lightweight portable sensors for health care

In this article, textile electrodes and semiconductor thin film piezoresistive sensors on plastic substrates were manufactured and fabricated with CMOS processes, respectively. An armband made of plain weave fabric, integrating embroidery textile electrodes of stainless steel (SS) and elastics to conform to human forearms were manufactured. The textile electrodes with an area of 1cm2 were made of two stitching layers for ease of manufacture and electrode robustness and connected through snap fasteners and SS/cotton threads to a signal processing electronic module. Piezoresistive sensors, consisting of n-type hydrogenated nanocrystalline silicon thin films patterned into rectangular bars and having metallic thin leads connecting the sensor to large pads were fabricated on 25µm thick flexible (polyimide) substrates. The textile and thin film piezoresistive sensors were connected to a small lightweight signal processing electronic module of a wireless portable unit for real-time monitoring and recording of the sensors signals. Surface electromyography signals of the forearms of a volunteer wearing the armband with textile electrodes exhibit amplitudes and baseline noise levels comparable to those obtained with standard Ag/AgCl electrodes. The piezoresistive sensor on plastic substrate was stuck with grease to the neck of a volunteer and small front/back neck movement monitored and recorded.

Dual-scanning System for Optical Estimation of Pilling Formation

In this paper we present and fully describe an experimental system, based on optical triangulation, for fabric quality control purposes in the textile industry, namely for the objective quantification of pilling formation. The chosen settings, together with the criteria used for each parameter of the system, are boarded and were fixed in order to optimize the performance of the implemented dual-scanning system. Four different experiments were carried out to test and characterize the implemented system. Regarding the application of this system, the experimental results obtained for the optical estimation of the pilling formation, on a set of five different fabrics, have been shown to be in agreement with the subjective grade classification, meaning that the implemented dual-scanning system can be used to objectively quantify this parameter.