Meta-aramid Fibers Research Articles

Dyeing and fastness properties of vat dyes on meta-aramid woven fabric

meta-Aramid fibers have an excellent heat-resistant property and are widely used for protective clothings such as fire-fighter suit and racing suit. They can also be used as military uniforms such as flight suit or army uniform. Vat dyes are specially used for military uniforms owing to outstanding fastness properties, earth tone shade, and near infrared (NIR) camouflage. In this study, 100 % meta-aramid woven fabric was dyed with three vat dyes using an exhaustion method and their dyeing and fastness properties were investigated. Color yields of the vat dyes on the meta-aramid fabric were found to be dependent upon dyeing temperature, liquor ratio, amount of reducing agent, and amount of salt. Dyeing behavior of the vat dye on the meta-aramid fiber was very similar to that on cellulose fibers. It was found that the meta-aramid fabric dyed with 1% owf of C.I. Vat Green 1 satisfied the tolerance of the reflectance spectrum of forest green color in the Korean military standard. Thermal stability and mechanical property of the meta-aramid fabric did not significantly affected by the vat dyeing process. Wash and perspiration fastness was generally good but rubbing and light fastness was unsatisfied.

Synthesis and Characterization of a Novel Aramid Fiber Liquid Crystalline Polymer

The-NH2 groups, as grafting initiators, are introduced to the surface of meta-aramid fibers by treating the fiber surface with dilute sodium hydroxide solution. A kind of new aramid fibers liquid crystalline polymer were synthesized by interfacial polymerization of mesogenic monomer DDBA, main-chain LCI containing sulfonate ionic monomer BY, sebacoyl dichloride and aramid fibers hydrolysed. The structure and properties of aramid fibers before and after modification were characterized by SEM, FTIR, and POM.

아라미드 종이의 특성에 대한 표면 개질 과정 조건의 영향

Surface modification of meta-aramid fibers was performed by phosphoric acid treatment. Surface morphology and element composition of untreated and treated fibers were analyzed by scanning electron microscope (SEM) and X- ray photoelectron spectroscopy (XPS). Effects of surface modification on the mechanical strength of aramid papers made from meta-aramid fibers and fibrid were investigated. Surface modification conditions were optimized by response sur- face analysis (RSA). Results show that phosphoric acid treatment increases the surface roughness and oxygen content of aramid fibers. They improve the interface bonding strength between aramid fibers and fibrid, which improves the tensile strength of aramid papers. The results of response surface analysis indicate that the tensile strength of aramid papers increases by 47.5% and reaches the maximum when meta-aramid fibers are treated with 21.1wt% phosphoric acid solu- tion at 39.3 o C for 36.7 min.

Fabrication of meta-aramid fibrid by precipitation

“Fibrid”, a type of fibrous particle used for binding, and the meta-aramid fibrids were successfully prepared by injecting the meta-aramid solution into the high shearing coagulation bath in this paper. The meta-aramid solution was prepared by dissolving the meta-aramid fibers in LiCl/DMAc solving system, and the mixture of water and DMAc was used as coagulation bath. The rotating speed, concentration of meta-aramid solution and the concentration of water in the coagulation bath were the main factors on effecting the formation and morphology of fibrids. The results showed that the length of meta-aramid fibrid decreased with the rotating speed and the content of water in coagulation bath increasing, and increased with the concentration of meta-aramid solution increasing. The morphology of meta-aramid fibrid were observed by optical microscope, a lower thermal property of meta-aramid firbid than meta-aramid fiber was observed in TGA which was mainly due to the breaking of hydrogen bonding and crystalline structure of meta-aramid fiber during the dissolving process, the results in TGA were consistent with the XRD, and the XRD curves showed that the non-crystalline structure were observed in meta-aramid fibrid.

Factors Affecting the Thermal Insulation and Abrasion Resistance of Heat Resistant Hydro-Entangled Nonwoven Batting Materials for Use in Firefighter Turnout Suit Thermal Liner Systems

This paper describes a study on heat resistant nonwoven batting materials used as components in the construction of thermal liners systems in firefighter turnout suits. It examines relationships between the fiber composition and construction of hydroentangled nonwoven battings and properties that can affect their performance when used in this application. Relationships between batting porosity, weight, thermal insulation, bulk and abrasion resistance are examined in hydroentangled constructions made with oxidized PAN, para-aramid and meta-aramid fibers. Correlations observed between the insulation of batting materials components and the thermal protective performance of integrated multilayered fabric systems used in firefighter turnout suits are described.

Fabrication of electrospun meta-aramid nanofibers in different solvent systems

Meta-aramid fibers were dissolved in four different solvent systems (DMAc, DMF, NMP, and DMSO) and two kinds of salts (LiCl and CaCl2) were also introduced in this paper. Meta-aramid fibers had a limited solubility in above four solvents, however, fast dissolution could be obtained after adding a certain amount of salt (LiCl or CaCl2). The concentration of salts was found to be an important role in affecting meltaging, dissolving time and viscosity of electrospun solution. Electrospun meta-aramid nanofibers mats were successfully prepared. A series of characterizations had been carried out by using SEM. The results shows the diameter of meta-aramid nanofibers ranging from 100 to 500 nm. The average diameter of the nanofibers increased with the concentration of meta-aramid fiber solution and the salt solution. A preferable morphology of meta-aramid nanofibers could be obtained under LiCl/DMAc system. While the electrospun nanofibers made in CaCl2/DMAc solvent system had a better performance in thermal stability than that prepared in LiCl/DMAc system. Among the four kinds of prepared nanofibers, the nanofibersmat electrospun in LiCl/DMAc system with a concentration of meta-aramid solution at 11 wt% exhibit the best mechanical properties.

Acid dyeing properties of meta-aramid fiber pretreated with PEO45-MeDMA derived from [2-(methacryloyloxy)ethyl] trimethylammonium chloride

A diblock copolymer (PEO45-MeDMA) derived from [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MeDMA) was synthesized and applied to the dyeing of the meta-aramid fibers with some acid dyes. This copolymer created positive charges on meta-aramid fiber surface and a strong attraction with anionic groups of acid dyes. Meta-aramid fabric was pretreated using the synthesized copolymer and then dyed with two commercial acid dyes. The dyeability was found to be directly dependent on the concentration of PEO45-MeDMA, pH in the dyebath as well as dye concentration. The color fastness of the copolymer pretreated dyed fabric was also evaluated.