Influence analysis of test speed on technical filament yarns behaviour in tensile test

V prispevku sta predstavljena dva različna načina nateznega preizkušanja linijskih tekstilij: natezno preizkušanje pri standardnih pogojih preizkušanja s standardnim dinamometrom in natezno preizkušanje pri ve- likih hitrostih. Raziskovali smo obnašanje treh tipov tehničnih filamentnih prej: dveh poliamidnih (PA 6.6 in PA 4.6) in polietilenteraftalatnega (PET) multifilamenta visokih trdnosti. Na podlagi rezultatov raziskave sklepamo, da deformacijska hitrost ($dot{epsilon}$) pri vseh treh preizkuševalnih prejah vpliva na natezne lastnosti materiala. To pomeni, da se mehanskih lastnosti in nateznega obnašanja prej pri velikih hitrostih obremenitve ne da pojasnjevati zgolj s podatki, dobljenimi pri standardnih pogojih preizkušanja, temveč je treba uvesti ustrezno metodo z višjimi hitrostmi preizkušanja.Two different ways of tensile testing of liner textiles, namely the tensile testing under standard conditions with a standard dynamometer and high-speed tensile testing are presented in the article. Within this research, we studied the behaviour of three types of high-tenacity multifilament technical filament yarns, i.e. two polyamide yarns (PA 6.6 and PA 4.6) and polyethylene terephthalate (PET). Based on the results of the research, we can conclude that the strain rate ($dot{epsilon}$) in all three tested yarns affected the material tensile properties. This means that the mechanical properties and tensile behaviour of technical yarns cannot be explained only with the data obtained under standard test conditions. For better understanding of the behaviour of technical yarns, it is necessary to introduce an appropriate method with high-speed testin

Application of Spectrophotometric Methods in Assessing the Influence of Alkaline Treatment on the Degree of Crosslinking of Cotton Cellulose with BTCA

Polycarboxylic acids appear to be the most promising nonformaldehyde crosslinking agents to replace the traditional, mostly formaldehyde-based, compounds. The most effective among these acids is 1,2,3,4-butanetetracarboxylic acid (BTCA). In this study, a comparison was made of the crosslinking effect on mercerized and on unmercerized as well as with different BTCA mass fractions crosslinked cotton fibres using FT-IR spectroscopy, the methylene blue method and water retention determination. The main purpose of the research was to evaluate how the structural changes of mercerized cotton (transformation of cellulose I into cellulose II) influence the crosslinking of cellulose fibres

Sistem praznin v vlaknih

The macrovoid system of poly(ethylene terephthalate) (PET) and poly(propylene) (PP) fibres was studied by small-angle x-ray scattering (SAXS). Commercial PET textile fibres were treated in different media and the influence on fibre homogeneity was followd by SAXS. PP technical fibres were manufactured on a laboratory spin-drawing device and subsequently drawn at different drawing conditions on a laboratory drawing device. The influence of drawing on the pore system was followed.V prispevku smo z ozkokotnim rentgenskim sipanjem (SAXS) proučili sistem mikrovotlin v polietilentereftalatnih (PET) in polipropilenskih (PP) vlaknih. Komercialna PET tekstilna vlakna smo obdelali v različnih medijih in spremljali vpliv pogojev obdelave na homogenost vlaken s SAXS. Konvencionalno barvanje vlaken v vodnem mediju in in toplotna obdelava vlaken v vročem zraku povzročita spremembe v sistemu por vlakna. Na laboratorijski predilno-raztezalni napravi smo izdelali tehnična PP vlakna ter določili vpliv raztezanja na sistem por v vlaknu. Raztezanje vpliva na oblikovanje sistema praznin v vlaknu

Structure-properties relations of the drawn poly(ethylene terephthalate) filament sewing thread

This article presents research into draw ratio influence on the structure-properties relationship of drawn PET filament threads. Structural modification influence due to the drawing conditions, i.e., the birefringence and filament crystallinity, on the mechanical properties was investigated, as well as the shrinkage and dynamic mechanical properties of the drawn threads. Increasing draw ratio causes a linear increase in the birefringence, degree of crystallinity, filament shrinkage, and a decrease in the loss modulus. In addition, loss tangent and glass transition temperature, determined at the loss modulus peak, were increased by drawing. The observed structural changes influence the thread\u27s mechanical properties, i.e., the breaking tenacity, elasticity modulus, and tension at the yield point increase, while breaking extension decreases by a higher draw ratio

Fibrillation of Lyocell fibres due to different treatment conditions

Razlike procesov pridobivanja različnih regeneriranih celuloznih vlaken povzročajo različno morfološko zgradbo vlaken, ki se kaže tudi v različnem nagnjenju k fibriliranju. Zaradi visoke orientacije in kristalinosti vlaken kažejo liocel vlakna močno težnjo k fibriliranju, t.j. cepljenju fibrilov vzdolž vlaken. Nabrekanje in mehanske obremenitve ta pojav pospešijo in ojačajo. Zelo tanki fibrili na površini vlaken in njihovo kodranje povzročijo povečano površino vlaken in s tem spremembo površine tkanin. Metoda, ki so trenutno na razpolago za ocenitev stopnje fibriliranja so še nepopolne. Spremembo površine vlakna kot funkcijo fibriliranja lahko zaznamo optično ali po spremembah otipa. V prispevku smo predstavili novo metodo zasledovanja fibriliranja s spremembo optičnih lastnosti tkanin, in sicer Tencel vlaken. Z obdelavo in kvantitativno analizo mikroskopskih slik smo določali spremembe oblike in velikosti por v tkanini, ki so nastale kot posledica različnih postopkov obdelane, n. pr. fibriliranje surove tkanine, encimatska obdelava in zamreženje liocel vlaken.The differences in the man-made cellulose fibre forming processes produce some varieties in the morphological structure of fibres, which shows in fibres\u27 different tendency to fibrillate, i.e. to split along the fibre axis. The basic parameters connected with the high degree of crystallinity and orientation of lyocell fibres are also the reason for lyocell fibres\u27 high tendency to fibrillate. Fibre swelling and mechanical stress promote this effect. Very fine fibrils on the fibre surface and their crimping increase the fibre surface and thereby influence the surface changes of the fabric. Some methods for following the formation of fibrils, their density and homogeneity have been proposed, but have proved to be insufficient. The changes of the fibre surface due to fibrillation can be followed optically or by handle changes. In the paper a new method for observing the changes of optical properties of lyocell fibres influenced by fibre fibrillation is given. The analyses were performed on Tencel fabrics. Processing and quantitative analysis of microscopic images was involved for studying the form and dimensions of fabric pores that were produced by different treatments, like raw fabric fibrillation, enzyme treatment and crosslinking of lyocell fibres

Elektropredenje

Electrospinning is a method based on the use of electrostatic forces for producing continuous fibres with the diameter from between ten nanometres to some micrometres. Such fine fibres cannot be produced with conventional methods for the production of nonwovens. The nanofibres formed with electrospinning have an exceptionally large active surface area per mass unit (fibre surface at diameter of 100 nm equals 40 $m^2$/g) and the spinning process itself enables a planned formation of the web structure (e.g. planned size of pores in the web by adjusting the nanofibre diameter and fibre thickness). Nanofibres can be electrospun from synthetic or natural polymers and their blends, from polymers with various nanoparticles (metal, ceramic etc), active substances etc. We can fabricate individual fibres, as well as webs with a random or planned fibre arrangement. Fibres with a complex structure, e.g. core shell or hollow fibres, can be produced with a special electrospinning method. Regarding the advantages demonstrated by the nanofibres fabricated with electrospinning, this procedure has become an important part of research in seve ral fields of use of technical textiles, e.g. shielding materials, air and oil filters in the car industry, agrotextiles and most of all medical textiles. The method can also be used in the production of batteries and photovoltaic cells. Apart from the apparatus designed for the research purpose in laboratories, pilot devices and the devices designed for the use in the industry can be found on the market. The paper comprises the introduction of the preparation procedure of nanofibres on an electrospinning apparatus, the morphological characteristics of fibres and the characteristics of electrospun webs in dependence of the conditions when forming fibres.Elektropredenje (electrospinning) je metoda, ki temelji na uporabi elektrostatskih sil za oblikovanje neskončnih vlaken s premerom med deset nanometri in nekaj mikrometri. Tako finih vlaken ni mogoče oblikovati s konvencionalnimi metodami izdelave netkanih tekstilij. Nanovlakna, oblikovana po postopku elektropredenja, imajo izjemno veliko aktivno površino na enoto mase (pri premeru 100 nm je površina vlaken 40 $m^2$/g), medtem ko sam postopek elektropredenja omogoča tudi načrtno oblikovanje strukture koprene (npr. načrtovanje velikosti por v kopreni z uravnavanjem premera nanovlaken in gostote vlaken). Po postopku elektropredenja lahko izdelamo nanovlakna iz sintetičnih ali naravnih polimerov in njihovih mešanic, polimerov z vključenimi različnimi nanodelci (kovinskimi, keramičnimi delci .), z vključenimi zdravilnimi učinkovinami itd. Oblikujemo lahko posamezna vlakna, kot tudi koprene z naključno ali načrtovano ureditvijo vlaken. Vlakna s kompleksno strukturo, kot na primer jedro-plašč ali votla vlakna, pa lahko proizvedemo po posebni metodi elektropredenja. Glede na prednosti, ki jih izkazujejo nanovlakna, oblikovana po postopku elektropredenja, je postal ta postopek zelo pomemben del raziskav na številnih področjih uporabe tehničnih tekstilij, kot so zaščitni materiali, zračni in oljni filtri za avtomobilsko industrijo, agrotekstilije in predvsem na področju medicine. Metoda je uporabna tudi za izdelavo materialov za baterije in fotovoltaične celice. Poleg naprav, ki so namenjene raziskavam v laboratorijskih obsegih, pa so na trgu že tudi pilotske naprave in takšne, ki so namenjene tudi industriji. V prispevku bomo predstavili pripravo nanovlaken na elektropredilni napravi, morfološke značilnosti vlaken in lastnosti izdelanih kopren v odvisnosti od pogojev oblikovanja vlaken

Structure-mechanical properties relationship of poly(ethylene terephthalate) fibers

The correlation between the fiber structure and mechanical properties of two different poly(ethylene terephthalate) fiber types, that is, wool and cotton types produced by three producers, was studied. Fiber structure was determinedusing different analytical methods. Significant differences in the suprastructure of both types of conventional textile fibers were observed, although some slight variations in the structure existed between those fibers of the same type provided by different producers. A better-developed crystalline structure composed of bigger, more perfect, and more axially oriented crystallites was characterized for the cotton types of PET fibers. Crystallinity is higher, long periods are longer, and amorphous domains inside the long period cover bigger parts in this fiber type in comparison with the wool types of fibers. In addition, amorphous and average molecular orientation is higher. The better mechanical properties of cotton PET fiber types, as demonstrated by a higher breaking tenacity and modulus accompanied by a lower breaking elongation, are due to the observed structural characteristics

Raman spectroscopic studies of structural changes in polyethylene terephthalate fibres

Polietilentereftalatna (PET) vlakna so med procesom njihovega oblikovanja in preoblikovanja, med barvanjem, plemenitenjem in med drugimi procesi izpostavljena visokim temperaturam. Toplotna obdelava pri temperaturah nad temperaturo steklastega prehoda vpliva na kristaliničnost, dimenzije kristalitov, strukturno periodičnost, kristalino in amorfno orientacijo, itd. Strukturne spremembe PET vlaken, ki jih povzroči toplotna obdelava v vodnem mediju ali vročem zraku, smo proučili z ramansko spektroskopijo, ki postaja zelo pomembna tehnika za karakterizacijo kemijskih in fizikalnih lastnosti polimerov v tekstilni kemiji. Osredotočili smo se na določitev strukturnih sprememb, ki izvirajo iz konformacijskih prehodov etilenglikolnega dela PET. Rezultati kažejo, da toplotna obdelava povzroči spremembe v trans/gauche konformacijskem razmerju. Ugotovili smo, da ima temperatura močnejši vpliv kot uporabljeni medij.Poly(ethylenterephthalate) PET fibres are exposed to high temperatures during the fibre formation process, dyeing, finishing and other processes. The thermal treatment of PET fibres above the glass transition temperature changes the crystallinity, crystals\u27 dimensions, structure periodicity, crystal and amorphous orientation, etc. We have studied the structural changes of PET fibres depending on different treatment media (water, air) using Raman spectroscopy. Raman spectroscopy is becoming one of the most significant techniques for characterization of the chemical and physical properties of polymers in textile chemistry. We focused on structural changes due to conformational transitions of ethylene glycol in PET fibres. The results show that thermal treatment causes an increase of trans/gauche conformational ratio with annealing temperature. The presented results show that the annealing temperature has greater influence on structural changes in PET samples than the used treatment medium