This work focused on the evaluation of the kinetics of dyeing polyester fabrics with high molecular weight disperse dyes, at low temperature by solvent microemulsion. This study also compared the ...effect of two non-toxic agro-sourced auxiliaries (
-vanillin and coumarin) using a non-toxic organic solvent. A dyeing bath consisting of a micro-emulsion system involving a small proportion of
-butyl acetate was used, and the kinetics of dyeing were analysed at four temperatures (83, 90, 95 and 100 °C). Moreover, the dyeing rate constants, correlation coefficient and activation energies were proposed for this system. It was found that
-vanillin yielded higher dye absorption levels than coumarin, leading to exhaustions of 88% and 87% for Disperse Red 167 and Disperse Blue 79, respectively.
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values of dyed polyester were also found to be higher for dye baths containing
-vanillin with respect to the ones with coumarin. In terms of hot pressing fastness and wash fastness, generally no adverse influence on fastness properties was reported, while
-vanillin showed slightly better results compared to coumarin.
The objective of this research were to study hydrophobicity and antibacterial activity of polyester fibers before and after modification by using silver nanoparticles as antibacterial agent and ...hexadecyltrimethoxysilane (HDTMS) as self cleaning agent. The research was conducted in stages, chemical preparation of silver nanoparticles, deposit of silver nanoparticles on polyester fiber, modification of polyester fiber through the addition HDTMS, and characterization. Modification of polyester fibers with silver nanoparticles and HDTMS was conducted through dipping method, followed by curing. Characterization was conducted by testing the contact angle and antibacterial activity against Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 35218. Silver nanoparticles has been prepared by adding sodium citrate and polyvinylalcohol as stabilizer. The addition of silver nanoparticles decreased hydrophobicity of polyester fibers without and with modification. Modification with HDTMS increased hydrophobicity of polyester fibers. Modification with silver nanoparticles and HDTMS increased antibacterial activity of polyester fabrics. Statistic analysis showed that there were significant differences in the antibacterial activity of polyester fibers against Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 35218
Bu çalışmanın amacı farklı sterilizasyon metodlarının elektroçekim polyester lifleri üzerindeki etkisini incelemektir. PET lifleri; ağırlıkça %10,15 ve 20 oranında polietilen tereftalat (PET) içeren ...çözeltilerden elektroçekim yöntemiyle üretilmiş ve etilen oksit (EO), otoklav (AU) ve ultraviyole (UV) ile sterilize edilmiştir. Üretilen yüzeylerin yüzey karakterizasyonu taramalı elektron mikroskobu (SEM), atomik kuvvet mikroskobu (AFM), yüzey gözeneklilik boyutu analizleri ve temas açısı ölçümleriyle gerçekleştirilmiştir. Yüzeylerin termal özellikleri Diferansiyel taramalı kalorimetre (DSC) testleri; mikro yapısal özellikleri Fourier Transform Infrared spektroskopisi (FTIR) ile araştırılmıştır. SEM çalışmaları farklı sterilizasyon yöntemlerinin, polimer konsantrasyonuna bağlı olarak büyük değişikliklere neden olduğunu göstermiştir. Artan polimer konsantrasyonu ile yöntemlerin etkileri azalma gösterse de, lif yapısı -özellikle EO sterilizasyonunda oldukça zarar görmüştür. Temas açısı değerlerinde UV sterilizasyonu sonrası büyük düşüş görülmüştür.
A series of poly(butylene succinate) (PBS) ionomers containing up to 14 mol% of sulfonated succinate units have been synthesized by polycondensation in the melt-phase. The copolyesters were obtained ...with weight average molecular weights oscillating between 33,000 and 72,000 g·mol−1. All copolyesters were semicrystalline with melting temperatures and enthalpies decreasing and glass transition temperatures increasing with the content of ionic units. The thermal stability of PBS was slightly reduced by the incorporation of these units, and it was also found that the copolyesters were stiffer but also more brittle than PBS. The hydrolytic degradability of PBS was enhanced by copolymerization, an effect that was much more pronounced in basic media.
POY yarns are well know and commercialized since 1970s. On the other hand, air-jet textured yarns are very common due to their unique structure which looks like natural spun-staple yarns. In the ...air-jet texturing process, the yarn is textured by overfeeding into a high-pressure of air to create a looped and more natural yarn appearance and also the bulkiness level of the yarn is controlled by input speed and jet-take out speed. This process reassigns flat, continous synthetic yarns into entangled, convoluted, bulky, spun like structured yarns. They are of higher bulk, exhibits increased covering power, have a more subdued lustre and are warmer in hand. Therefore, air-jet textured yarns possess some unique properties that require investigation. Hence, in this study, first the texturing process is introduced briefly and its principle of manufacturing is illustrated, later four different types of yarns were produced with two different fibre cross-sections at the three different nozzle types and three different core yarn feeding. The produced yarn production details are given and their breaking strength, elongation and work of rupture are studied along with their morphological structures by using light microscope and SEM. The aim of this study is to investigate the effect of POY fibre cross-section on air-jet textured yarn mechanical properties. The overall results showed that coarser air-jet textured yarns with a round shape have higher breaking strength, elongation and work of rupture than the trilobal shaped yarns. On the other hand, half matted yarn which was applied TiO2 has also presented better breaking strength and elongation.
The research aims to demonstrate that mastering RP by lawstudents contributes to their advance in English-language interaction in
international environment. The relevance and novelty of the study lie
...in teaching (based on the interdisciplinary approach) RP skills to Law
Institute nonimmigrant students immersed in the nonlinguistic
intercultural environment. The data revealed that for 25% of
respondents, specific difficulties were caused by poly-stressed words
having no accentuation coincidence in Russian and English, in
particular, verbs with postpositive elements typical for the English
language. The research conclusions highlight the necessity for the law
students to master Received Pronunciation in using multisyllabic
words.
La investigación tiene como objetivo demostrar que el dominio
de la RP por los estudiantes de derecho contribuye a su avance en la
interacción del idioma inglés en el entorno internacional. La relevancia
y novedad del estudio radica en la enseñanza (basada en el enfoque
interdisciplinario) de habilidades de RP para estudiantes no
inmigrantes del Instituto de Derecho inmersos en el entorno
intercultural no lingüístico. Los datos revelaron que para el 25% de los
encuestados, las dificultades específicas fueron causadas por palabras
poli-estresadas que no tenían coincidencia de acentuación en ruso e
inglés, en particular, verbos con elementos postpositivos típicos del
idioma inglés. Las conclusiones de la investigación resaltan la
necesidad de que los estudiantes de derecho dominen la pronunciación
recibida al usar palabras multisilábicas.
A cyclic acetal of dimethyl l-tartrate (dimethyl 2,3-di-O-methylene l-threarate, Thx) was used as comonomer of dimethyl terephthalate (DMT) in the polycondensation with 1,6-hexanediol (HD) in the ...melt. Random copolyesters PHTxThxy with contents in tartrate units up to 50% were obtained with satisfactory molecular weights (Mw between 20,000 and 50,000) and dispersities slightly above 2, and without apparent discoloration. The copolyesters started to decompose above 300 °C. The Tg of the copolyesters oscillated between +9 and −9 °C with values steadily decreasing with increasing contents in Thx units. All the copolyesters as well as the homopolyester entirely made of tartrate units were semicrystalline with Tm falling from ∼145 °C for PHT to ∼70 °C for PHThx with intermediate values decreasing as the content in Thx increased. Copolyesters containing up to 30% of tartrate units were able to crystallize from the melt at crystallization rates that were delayed by the presence of tartrate units. The PHT70Thx30 copolyester displayed significant hydrodegradability when incubated in aqueous buffer and also certain biodegradability when subjected to the action of porcine pancreas lipases.
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Penelitian ini menggunakan serat alami pelepah sawit sebagai matriks dalam pembuatan bio composite dan resin poliester digunakan sebagai filler. Pembuatan bio composite dikempa menggunakan mesin ...hotpress pada suhu 70°C selama 20 menit dengan penekanan 30 kg/m2. Panjang serat divariasikan dengan ukuran 2, 4, 6, 8, dan 10 cm. Parameter berupa pengujian sifat fisis (densitas, porositas, dan daya serap air), pengujian sifat mekanik (kuat tekan, tarik, dan impak), dan analisa mikrostruktur menggunakan Scanning Electron Microscope (SEM). Hasil pengujian nilai optimum sifat fisis pada komposisi serat pelepah sawit yaitu 75%:25% dengan panjang serat pelepah sawit 10 cm yang memiliki nilai sifat fisis densitas 0,793 gr/cm3, porositas 0,134%, daya serap air 0,169% dan nilai sifat mekanik kuat tekan 19,234 MPa, kuat tarik 725,95 MPa, impak 1,1262 J/mm2. Hasil SEM, sifat fisis, dan sifat mekanik mendukung bio composite memenuhi kriteria "Medium Board" berdasarkan JIS A 5905:2003 dan dapat dimanfaatkan sebagai material alternatif pengganti bahan kayu.
Warp knitting technology combines the two properties of dimensional stability and elasticity which are provided from woven and knitted fabrics separately. These fabrics consist of several threads ...(warp) which are formed as loops via needles and run through the fabric mainly in a vertical direction. These fabrics may be produced on a flat or a circular warp knitting machines. This study aims to investigate the influence of washing cycles (1, 5 and 20) on stretching (%) and air permeability properties of the polyester warp knitted fabrics of different weight. In order to analyze the effect of washing process on stretching ratios (%) and air permeability of the samples; Fyrma fabric extensometer and SDL Atlas M021A model Air Permeability Tester devices were used respectively. Additionally, the changes in fabric weight according to washing cycles of 1, 5 and 20 were also evaluated. According to test results; the stretching properties and air permeability values of the polyester warp knitted fabrics produced in different weights varied according to the laundering cycle which emphasized that caring processes should also be considered during the evaluation of mechanical properties (such as stretching, air permeability properties) of polyester warp knitted fabrics.
The influence of the silk-like finishing process on the frictional properties of polyester fabrics was examined by assessing fibre-to-metal friction through parameter R in a 100% polyester woven ...fabric processed under variable conditions of NaOH concentration and vaporization time. The alkali concentration influenced static and dynamic friction in the fabric, whereas the vaporization time only affected static friction. Process variables can be used to predict the frictional performance of silk-like finished fabrics via parameter R for dynamic friction. Fabric weight loss by effect of the silk-like finishing treatment influences the coefficient of fibre-to-metal friction. Industrially, the silk-line finishing process is typically monitored through weight loss in the finished fabric. As shown here, however, it can also be monitored by assessing changes in fabric surface via the dynamic friction parameter R.
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