Needleless electrospun polyacrylonitrile nanofibers mats - Preparation, stabilization, carbonization and composite formation

The publications have been structured thematically, starting with basics such as the investigation of optimal electrospinning parameters for nanofiber mats. Subsequently, more complex topics such as the formation of composites such as the mixing of PAN with gelatin and experimental investigations of metal-carbon composites are carried out. Fecha de lectura de Tesis Doctoral: 18 diciembre 2018.This dissertation deals with NEEDLELESS ELECTROSPUN POLYACRYLONITRILE NANOFIBER MATS - PREPARATION, STABILIZATION, CARBONIZATION AND COMPOSITE FORMATION and consists of a total of nine thematic chapters. At the beginning of the work, the first chapter gives an overview of the research as well as short descriptions of important research results. In addition, theoretical frameworks of the work are presented and the state of the art is examined, with a focus on electrospinning technology and the influences of parameters in the electrospinning process. Subsequently, the oxidation and stabilization processes of nanofiber mats are presented. The second chapter focuses on the methodology of the investigations and describes materials, devices and research methods used in this work. This chapter begins with an overview of the materials used. Then, the structure and principle of the needleless electrospinning machine is vividly illustrated. In addition, special attention is paid to the sample preparation and also to the fixing methods of nanofiber mats during the stabilization process. Several attempts to fix nanofibers during the stabilization process are illustrated and explained in more detail. In addition, experimental framework conditions for stabilization and carbonization parameters are presented and clearly described. This chapter concludes with various materials characterization methods that will be used during the research work in this dissertation. The research results can be found in chapters three to eight, where they are presented as a compendium of publications. In total, these chapters are based on six publications that have already been published, accepted or submitted

New testing device for air permeability

Air permeability is used to characterize textile fabrics with respect to their usability as a garment or filter, airbag or parachute. It depends on the fabric’s porosity, air voids in the fabric, yarn specifications, thickness and other parameters, making it hard to calculate it reliably from other parameters. At the same time, measuring air permeability requires relatively expensive and complex equipment that cannot simply be built by everybody. Here, we suggest a simple device, which can be built from inexpensive components and correlates air permeability to a time measurement. We show that these values are highly correlated with the results gained by the frequently used standard EN ISO 9237

Low-cost test setup for motorcycle protective clothing abrasion examination

The personal protective equipment and protective clothing for motorcyclists reduce physical injuries to victims of road accidents. Therefore, it is important that the protective clothing complies with a number of test standards, which must be taken into account during the manufacturing process. However, the EN17092-1 to 6 standard does not necessarily correspond to a real accident situations and these testing procedures are time consuming. In this study, a simple and inexpensive self-constructed device for testing the abrasion resistance of motorcycle protective clothing was developed and evaluated. Different types of textiles and leather with and without coating were tested and compared. According to the results of this study, not only leather but also textiles offer good abrasion resistance results. The results show that the strength of an impact significantly changes the abrasion resistance. The developed test method can provide a good alternative as a low-cost and simple test method of abrasion resistance of motorcycle protective clothing

Applications of Smart Clothing – a Brief Overview

Smart clothing is the next evolutionary step in wearable devices. It integrates electronics and textiles to create functional, stylish and comfortable solutions for people's daily needs. The concept includes not only clothing, which is a covering mechanism for the body but also has the function of tracking body indicators in certain situations. The review introduces the classification and concept of smart clothing, the application areas such as sports, workwear, healthcare, military and fashion. It will also outline the current state of smart clothing and the latest developments in the field, and discuss future developments and challenges

New Polymers for Needleless Electrospinning from Low-Toxic Solvents.

Wortmann M, Frese N, Sabantina L, et al. New Polymers for Needleless Electrospinning from Low-Toxic Solvents. Nanomaterials (Basel, Switzerland). 2019;9(1): 52

Self-healing materials for potential use in textile and clothing applications

Self-regenerating, polymer-based textiles emulate living organisms’ ability to heal broken skin and other lesser injuries. To achieve this effect, either intrinsic or extrinsic methods of having polymeric compounds mend these damages can be employed. Depending on the method used, the handling and results of the self-regenerating effect differ. This allows for different areas of application. The focus of this paper is to discuss some of these potential textile applications as well as related research and developments in the area of self-healing materials

Fixing PAN Nanofiber Mats during Stabilization for Carbonization and Creating Novel Metal/Carbon Composites

Polyacrylonitrile (PAN) is one of the materials most often used for carbonization. PAN nanofiber mats, created by electrospinning, are an especially interesting source to gain carbon nanofibers. A well-known problem in this process is fixing the PAN nanofiber mats during the stabilization process which is necessary to avoid contraction of the fibers, correlated with an undesired increase in the diameter and undesired bending. Fixing this issue typically results in breaks in the nanofiber mats if the tension is too high, or it is not strong enough to keep the fibers as straight as in the original state. This article suggests a novel method to overcome this problem by electrospinning on an aluminum substrate on which the nanofiber mat adheres rigidly, stabilizing the composite and carbonizing afterwards either with or without the aluminum substrate to gain either a pure carbon nanofiber mat or a metal/carbon composite

Electrospinning of Chitosan for Antibacterial Applications—Current Trends

Chitosan is a natural biopolymer that can be suitable for a wide range of applications due to its biocompatibility, rigid structure, and biodegradability. Moreover, it has been proven to have an antibacterial effect against several bacteria strains by incorporating the advantages of the electrospinning technique, with which tailored nanofibrous scaffolds can be produced. A literature search is conducted in this review regarding the antibacterial effectiveness of chitosan-based nanofibers in the filtration, biomedicine, and food protection industries. The results are promising in terms of research into sustainable materials. This review focuses on the electrospinning of chitosan for antibacterial applications and shows current trends in this field. In addition, various aspects such as the parameters affecting the antibacterial properties of chitosan are presented, and the application areas of electrospun chitosan nanofibers in the fields of air and water filtration, food storage, wound treatment, and tissue engineering are discussed in more detail

Nonclassical Attack on a Quantum Key Distribution System

The article is focused on research of an attack on the quantum key distribution system and proposes a countermeasure method. Particularly noteworthy is that this is not a classic attack on a quantum protocol. We describe an attack on the process of calibration. Results of the research show that quantum key distribution systems have vulnerabilities not only in the protocols, but also in other vital system components. The described type of attack does not affect the cryptographic strength of the received keys and does not point to the vulnerability of the quantum key distribution protocol. We also propose a method for autocompensating optical communication system development, which protects synchronization from unauthorized access. The proposed method is based on the use of sync pulses attenuated to a photon level in the process of detecting a time interval with a signal. The paper presents the results of experimental studies that show the discrepancies between the theoretical and real parameters of the system. The obtained data allow the length of the quantum channel to be calculated with high accuracy

Electrospun Carbon Nanofibers from Biomass and Biomass Blends—Current Trends

In recent years, ecological issues have led to the search for new green materials from biomass as precursors for producing carbon materials (CNFs). Such green materials are more attractive than traditional petroleum-based materials, which are environmentally harmful and non-biodegradable. Biomass could be ideal precursors for nanofibers since they stem from renewable sources and are low-cost. Recently, many authors have focused intensively on nanofibers’ production from biomass using microwave-assisted pyrolysis, hydrothermal treatment, ultrasonication method, but only a few on electrospinning methods. Moreover, still few studies deal with the production of electrospun carbon nanofibers from biomass. This review focuses on the new developments and trends of electrospun carbon nanofibers from biomass and aims to fill this research gap. The review is focusing on recollecting the most recent investigations about the preparation of carbon nanofiber from biomass and biopolymers as precursors using electrospinning as the manufacturing method, and the most important applications, such as energy storage that include fuel cells, electrochemical batteries and supercapacitors, as well as wastewater treatment, CO2 capture, and medicine