Energy absorption from composite reinforced with high performance auxetic textile structure

The objective of this study is to analyze the impact behavior on the basis of energy approach of weft knitted structures, namely a jersey composite and an auxetic composite using high performance yarns. Weft knitted fabrics were produced with the same structural and machine parameters, using 100% para-aramid and hybrid (47% para-aramid and 53% polyamide) structure. Composite fabrication was achieved through hand lay-up using epoxy resin. Negative Poisson ratio of the reinforcing auxetic fabric was transferred from the fabric to the composite developed. Results obtained by drop weight dart impact test show that the impact experiment with different impact loads confirmed the auxetic composites, regardless de material composition, have an increase in the total energy absorption compared to jersey reinforced composite, approximately 2.5 and 4 times more for para-aramid and hybrid composite, respectively. Auxetic composites developed within this work present great potential for applications in different areas, mainly where energy absorption is a key factor to be considered, such as in protection, sports among others

Plasma technology applied in textile industry

Plasma technology applied to textiles is a dry, environmentally and worker friendly method to achieve surface alteration without modifying the bulk properties of different materials. In particular, atmospheric non-thermal plasmas are appropriate because most textile materials are heat sensitive polymers and applicable in a continuous processes. In the last years plasma technology has become a very active, high growth research field, assuming a great importance among all available material surface modifications in textile industry. The main objective of this work is to present an update on the current state of art relating plasma technologies applied to textile industry. The main effects obtained by the application of plasma discharge and all the textile production chain such as: desizing, mercerization, dyeing, printing, composite and finishing will be superficially discussed

Reuse of effluent from dyeing process of polyamide fibers modified by double barrier discharge (DBD) plasma

Published online: 27 Feb 2015Low-temperature plasma technology becomes more and more attractive compared with traditional wet processes in textile preparation and finishing due to its high efficiency and low environmental impact. The objective of this study was to investigate the influence of dielectric barrier discharge plasma treatment on the trichromic dyeing process of polyamide 6.6 (PA66) and the reuse of the generated effluents for new dyeing processes. Chemical and physical characterization of the plasma-treated polyamide fibers was studied by means of static and dynamic contact angle, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy micrographs, and atomic force microscopy (AFM). Plasma treatment greatly increases the hydrophilicity and adhesion of PA66, due to the increase of polar groups and roughness on the fibers surface as confirmed by XPS and AFM. The kinetics of dyeing is quicker but leveled with high rubbing, light, and washing fastness quality. The reuse of the effluent obtained after dyeing of the plasma-treated fabrics showed excellent results of reproducibility, uniformity, and washing fastness. It was possible to reproduce the standard color for three dyeing cycles using the same effluent reducing the effluent load with a significant diminution in costs and environmental impact.Andrea Zille (C2011- UMINHO-2C2T-01) acknowledges funding from Programa Compromisso para a Ciencia 2008, Portugal

Functionalization of textile materials by double barrier discharge plasma

The pre-treatment of textile materials by non-thermal plasma technologies can offer many advantages over conventional chemical processes used to surface modification. This technology doesn’t involve the use of water and chemical reagents, resulting in a more eco-friendly and economical process. In this study air atmospheric pressure plasma treatment at normal ambient conditions was applied in various textile materials, namely: polyamide, polyester, acrylics and wool. The pre-treated textile materials were characterized using advanced instrumental techniques including X-ray photoelectronic spectroscopy (XPS), differential scanning calorimetry (DSC) atomic force microscopy (AFM) and scanning electron microscopy (SEM). Wettability analysis with different liquids was conducted to study static contact angle as well as surface energy and adhesion work of the plasma-treated fibrous materials. Chemical and physical characterization of the fabric confirmed significant surface alteration. Surface modification concerning the improvement of adhesion regarding a functionalizing substance, i.e. phase change materials (PCM) microcapsules was also investigated

Potential use of nonwoven for acoustic absorption/ Uso potencial de não-tecidos para absorção acústica

The use of nonwoven for technical implementation has increased considerably in recent years in most areas, not as a simple replacement for other materials, but as a product with specific properties which can be used for various purposes. It’s specific structure, resulting from the interaction between the raw materials and the manufacturing process, has been successful in several applications, providing, in according to the field, resistance, comfort, acoustic absorption and structure lightness. Therefore, from a brief review of the literature, the objective of this paper is to present the main techniques of web bonding and web forming for the production of nonwoven and present its potential for application in acoustic absorption when applied in civil area

Screen printing of cotton fabric with hydrochromic paste: evaluation of color uniformity, reversibility and fastness properties

Smart textiles are promising for the future of the textile industry, providing natural fibers with attractive and interactive features. Within this context, it is possible to emphasize the chromic materials, as, for example, the hydrochromic, which alter their visual properties (color) through an external stimulus (water). The purpose of this work is to functionalize and characterize cotton knitted fabric with hydrochromic agent studying the reversibility and fastness properties of the print. It was observed that the particles are well dispersed and adhered to the natural fiber surface and did not display significant changes in the color after subsequent washing and rubbing fastness cycles.智能纺织品为纺织工业的未来带来了希望, 它提供了具有吸引力和互动功 能的天然纤维. 在这种情况下, 可以强调铬材料, 例如水变色材料, 通过外部 刺激（水）改变其视觉特性（颜色）. 本研究的目的是利用水致变色剂对 棉针织物进行功能化和表征, 研究印花的可逆性和牢度性能. 经观察, 这些 颗粒在天然纤维表面分散良好, 粘附在纤维表面, 在随后的洗涤和摩擦牢度 循环后, 颜色没有明显变化

Retomando a medição no ensino médio : uma experiência didática

Apresentamos neste trabalho uma experiência em sala de aula realizada no Colégio de Aplicação da UFRGS, na disciplina de Enriquecimento Curricular intitulada “Que medida é esta?”, na qual os alunos desenvolveram atividades, experimentais e de outros tipos, envolvendo a medição como um processo de aquisição de dados. Foram elaborados guias de atividades, com tarefas e desafi os, que orientaram o trabalho dos alunos, primeiro em pequenos grupos (dois ou três alunos por grupo), nos quais realizaram medições, análise de dados qualitativos e quantitativos, responderam a questões específi cas e a questionamentos sobre os dados e resultados por eles obtidos. As descobertas, os conceitos trabalhados e os resultados obtidos eram sempre confrontados e socializados ao fi nal do encontro, envolvendo os alunos em discussões, complementadas ou não pelo professor. O aumento do interesse e participação dos alunos na execução das tarefas e questionamentos propostos, na prontidão e pré-disposição positiva para iniciar novas atividades, sem contar a qualidade dos registros, a satisfação na realização das atividades e na socialização dos resultados validaram o trabalho desenvolvido e os objetivos gerais e aspirações por nós vislumbrados no planejamento inicial.In this work is presented a classroom experience realized at “Colégio de Aplicação da UFRGS” (Public Rio Grande Do Sul Federal High School), at the curricular enrichment discipline entitle “What measure is this?”, in which the students developed experimental activities involving the measurement as an acquisition process of data. Were elaborated activities guides, based on challenges, guiding the students tasks, fi rst in reduced groups (two or three students by group), collecting measurements, qualitative and quantitative data analysis, answering specifi c questions and questions about the collected information. The discoveries and concepts were always discussed and worked in the end of the meeting, involving the students in the discussion, supplemented or not by the teacher. The increased interest and participation of the students about the tasks execution and question proposed, in the readiness and positive pre-disposition to start new activities, in addition to the quality of the records, the satisfaction in the activities achieved and socializing resolutions validated the work and the general goals and aspirations projected in the planned activities

A Review of Target Mass Corrections

With recent advances in the precision of inclusive lepton--nuclear scattering experiments, it has become apparent that comparable improvements are needed in the accuracy of the theoretical analysis tools. In particular, when extracting parton distribution functions in the large-x region, it is crucial to correct the data for effects associated with the nonzero mass of the target. We present here a comprehensive review of these target mass corrections (TMC) to structure functions data, summarizing the relevant formulas for TMCs in electromagnetic and weak processes. We include a full analysis of both hadronic and partonic masses, and trace how these effects appear in the operator product expansion and the factorized parton model formalism, as well as their limitations when applied to data in the x->1 limit. We evaluate the numerical effects of TMCs on various structure functions, and compare fits to data with and without these corrections.Comment: 41 pages, 13 figures; minor updates to match published versio

Prevention of hypertension in patients with pre-hypertension: protocol for the PREVER-prevention trial

<p>Abstract</p> <p>Background</p> <p>Blood pressure (BP) within pre-hypertensive levels confers higher cardiovascular risk and is an intermediate stage for full hypertension, which develops in an annual rate of 7 out of 100 individuals with 40 to 50 years of age. Non-drug interventions to prevent hypertension have had low effectiveness. In individuals with previous cardiovascular disease or diabetes, the use of BP-lowering agents reduces the incidence of major cardiovascular events. In the absence of higher baseline risk, the use of BP agents reduces the incidence of hypertension. The PREVER-prevention trial aims to investigate the efficacy, safety and feasibility of a population-based intervention to prevent the incidence of hypertension and the development of target-organ damage.</p> <p>Methods</p> <p>This is a randomized, double-blind, placebo-controlled clinical trial, with participants aged 30 to 70 years, with pre-hypertension. The trial arms will be chlorthalidone 12.5 mg plus amiloride 2.5 mg or identical placebo. The primary outcomes will be the incidence of hypertension, adverse events and development or worsening of microalbuminuria and of left ventricular hypertrophy in the EKG. The secondary outcomes will be fatal or non-fatal cardiovascular events: myocardial infarction, stroke, heart failure, evidence of new sub-clinical atherosclerosis, and sudden death. The study will last 18 months. The sample size was calculated on the basis of an incidence of hypertension of 14% in the control group, a size effect of 40%, power of 85% and P alpha of 5%, resulting in 625 participants per group. The project was approved by the Ethics committee of each participating institution.</p> <p>Discussion</p> <p>The early use of blood pressure-lowering drugs, particularly diuretics, which act on the main mechanism of blood pressure rising with age, may prevent cardiovascular events and the incidence of hypertension in individuals with hypertension. If this intervention shows to be effective and safe in a population-based perspective, it could be the basis for an innovative public health program to prevent hypertension in Brazil.</p> <p>Trial Registration</p> <p>Clinical Trials <a href="http://www.clinicaltrials.gov/ct2/show/NCT00970931">NCT00970931</a>.</p