Search

The melt spinning process of poly (trimethylene terephthalate) was modified by the inclusion of horizontal isothermal bath (HIB) in the extrusion line. Several parameters including liquid depth, liquid temperature, and take-up speed were utilized in this study. The structural and mechanical properties of the fibers were characterized by DSC, X-ray, SEM, optical birefringence, and tensile testing. The results showed that the bath treatment increased considerably the fiber birefringence up to 0.066 by 66% and increased the crystallinity up to 47.94% by 100% compared to the control (no HIB) fibers. Drawing the HIB fibers with a low draw ratio (DR) of 1.11 increased the tensile strength up to 4.76 g/d and reduced the tensile strain down to 51.76%. Such strength is greater than the maximum value of 3.3 g/d reported before. The obtained results can widen application of PTT fibers in technical woven/nonwoven fiber products.

In this study, PET (intrinsic viscosity of 1.05 dl/g) was melt processed with a horizontal isothermal bath (HIB) treatment. Tensile properties of PET fiber samples were highly increased by using the HIB. The process-structure-property relationship of control (no HIB) and HIB fiber samples were characterized by tensile testing, differential scanning calorimetry, birefringence measurement, scanning electron microscopy and hot-air shrinkage measurements. It was found that HIB fiber samples, which had been subjected to post-drawing process, had a high degree of molecular chain orientation, that is, a high birefringence, high crystallinity and a fibrillar structure. The best tensile property acquired from a HIB-drawn PET fiber sample was 10.24 g/d in tenacity, 114.17 g/d in modulus, and 13.49% in elongation at break. Applying the HIB in the melt spinning process was simple and required only small process space; hence, it is cost effective. In addition, acquiring HIB fiber samples was successful at a final take-up speed of 2,500 m/min. Hence, this HIB-assisted melt spinning technology has a high potential to be used in industries for technical textiles applications. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

β-Siklodekstrinler (β-CD), inklüzyon kompleksleri oluşturabilmektedirler ancak tekstil malzemeleriyle doğrudan kovalent birbağ oluşturamamakta ve bu nedenle bazı siklodekstrin türevleri çeşitli substratlara kimyasal olarak bağlanmalarını sağlamak içinreaktif gruplarla sentezlenmektedir. Bu araştırmada, itakonik asitli modifiye β-CD (CDI), plazma teknolojileri uygulanarak pamuklukumaş üzerine aşılanmıştır. Aşılama uygulaması için atmosferik basınç plazma reaktörü (APPJ) ve atmosferik basınç akkor deşarjı(APGD) olmak üzere iki plazma tekniği uygulanmıştır. Pamuklu kumaşın yüzeyinde reaktif siklodekstrin (CDI veya CDI / AkrilikAsit) aşılama kopolimerizasyonu incelenmiştir ve yüzey pamuk üzerine sabitlenmiş β-siklodekstrin'in performansı (molekülerkapsülleme için siklodekstrin boşluklarının erişilebilirliği) değerlendirilmiştir. Her bir plazma yönteminin, selülozik kumaşınözellikleri üzerindeki etkisi araştırılmıştır. Sonuçlar, selülozun yüzeyinde plazma aktivasyonunun meydana geldiğini ve serbestradikallerin, selülozun polimerik zincirlerinde herhangi bir bozulma olmadan CDI / AA'yla kolayca reaksiyona girebildiğinigöstermiştir. Liflerin yüzeyine bağlı CD nanoparçacıklarının varlığı ekli CD'lerin inklüzyon kompleksleri oluşturma kabiliyetinin yanısıra SEM kullanılarak da gösterilmiştir., -Cyclodextrin (β-CD) is capable of forming inclusion complexes, but it cannot form a direct covalent bond with textilematerials, hence some cyclodextrin derivatives have been synthesized with reactive groups to allow them to chemically bind tovarious substrates. In this research, the modified β-CD with itaconic acid (CDI) was grafted on to the cotton fabric by applying plasmatechnologies. Two methods of plasma techniques, atmospheric pressure plasma reactor (APPJ) and atmospheric pressure glowdischarge (APGD) were applied for the graft treatments. The grafting copolymerization of the reactive cyclodextrin (CDI orCDI/Acrylic Acid) on the surface of cotton fabric was studied and the performance (accessibility of cyclodextrin cavities formolecular encapsulation) of -cyclodextrin fixed onto the surface cotton was evaluated. The effect of each plasma treatment methodon the characteristics of the cellulosic fabric was investigated. The results showed that plasma activation was occurred on the surfaceof cellulose and free radicals can easily react to CDI/AA without any degradation on the polymeric chains of cellulose. The presenceof anchored CD nanoparticles on the surface of the fibers was demonstrated by using SEM as well as the ability of the attached CDsto form inclusion complexes.

Several techniques and treatments have been developed for the production of high-performance nylon-6 fibers. The inherent problems of low productivity, high production cost, and high energy consumption, complexity of chemical reaction, mass transfer, and waste recovery systems make most of them inappropriate for industrial application. Horizontal isothermal bath (hIB) is an alternative ecofriendly simple treatment that can be used during melt spinning process for production of technical textile fibers. The efficacy of hIB in improving the mechanical properties of multifilament nylon-6 yarn is studied in this research. The results showed that such treatment can increase the molecular orientation of the amorphous and crystalline functions up to 0.54 and 0.983, respectively, and raised both the amorphous isotropy and fiber birefringence by 67 and 45%, respectively. Hot drawing of the yarn at a very low draw ratio of 1.38, increased the tenacity and modulus up to 10 and 43.9 g/den, respectively, and decreased the elongation to 27%. POLYM. ENG. SCI., 55:2457–2464, 2015. © 2015 Society of Plastics Engineers

A detailed study was conducted to investigate the effects of horizontal isothermal bath (hIB) on the production of ultra-high performance polypropylene filaments. Two different commercial PP polymers were used with the melt flow rate of 4.1 and 36 g/10 min. The optimum process conditions depended on polymer molecular weight. Fibers showed distinct precursor morphology for each at each optimum process condition. However, two sets of filaments demonstrated similar fiber tenacity and modulus of about 7 and 75 g d−1, respectively, for as-spun and more than 12 g d−1 for tenacity and more than 190 g d−1 for modulus values of drawn fibers after just 1.49 draw ratio. The mean value for the modulus after the drawing process for the high melt flow rate was 196 g d−1. The theoretical modulus of PP is 35–42 GPa19, (275–330 g d−1), shows the hIB fiber's modulus performance is approaching its theoretical maximum value. Fibers had greatly improved thermal properties, degree of crystallinity, crystalline and amorphous orientation factors. The hIB spinning system produced highly oriented and predominantly amorphous structure for as-spun fibers and a well-defined, highly oriented crystalline fibrillar and amorphous structure after drawing process with the draw ratios lower than 1.5. POLYM. ENG. SCI., 55:327–339, 2015. © 2014 Society of Plastics Engineers

A number of production methods have been developed for high-performance fibers; however, most processes use toxic solvents or generate a lot of unwanted by-products. Our research resulted in the development of a new family of high-performance polypropylene (PP) fibers by utilizing a simple, ecologically friendly bath (ECOB). Various commodity polymers can be used with ECOB melt spinning system at high throughputs and performance benefits. Our treated as-spun PP fibers had a highly oriented, but not crystalline precursor morphology with fa up to 0.6 generating superior mechanical properties. After drawing at draw ratios of 1.49 at 120 °C, highly oriented crystalline and amorphous phases were achieved for the drawn fibers with fc and fa values of 0.95 and 0.87, respectively. This fine structure for ECOB-treated fibers resulted in tenacity close to 12 g/d, initial modulus higher than 150 g/d, and ultimate elongation at break of 20 %. The polymer melting point of the new fibrillar PP fibers increased by 9 °C.

The effect of three commercial inorganic additives supplied by Ciba Speciality Chemicals, Germany namely, Irgaguard B 5000 (carrier of Ag/ Zn zeolite), Irgaguard B7000 (carrier of Ag / Zn glass) and Irgaguard 1000 (triclosan) on the properties of polypropylene fibers was studied. These additives 0.1- 2 %(w/w) concentrations were well mixed to preheated isotatic PP chips and added into the hopper tanks of a Fourne’ double extruders machine together with purged nitrogen gas and melt extruded at 250oC to produce the continuous fibers. Characterization of the produced PP / Irgaguard composite fibers was carried out by Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimeter (DSC) to follow up the thermal stability of fibers, determination of the melting point and the percentage crystallization of the spun fibers. Mechanical properties of the composite fibers including count number, tensile strength, elongation, modulus and tenacity were analyzed and compared to the PP control. Transmission scanning electron microscopy (TEM) was studied to investigate the morphology of the composite fibers. These PP⁄ Irgaguard composite fibers have shown permanent antibacterial activity which was tested against E.coli, S.aureus and the antistatic property was determined.

Biomaterial nerve cuffs are a clinical alternative to autografts and allografts as a means to repair segmental peripheral nerve defects. However, existing clinical biomaterial constructs lack true incorporation of physical guidance cues into their design. In both two- and three-dimensional systems, it is known that substrate geometry directly affects rates of axon migration. However, the ability to incorporate these cues into biomaterial scaffolds of sufficient porosity to promote robust nerve regeneration in three-dimensional systems is a challenge. We have developed fibrin constructs fabricated by a sacrificial templating approach, yielding scaffolds with multiple 10-250 μm diameter conduits depending on the diameter of the template fibers. The resulting scaffolds contained numerous, highly aligned conduits, had porosity of ∼ 80%, and showed mechanical properties comparable to native nerve (150-300 kPa Young's modulus). We studied the effects of the conduit diameters on the rate of axon migration through the scaffold to investigate if manipulation of this geometry could be used to ultimately promote more rapid bridging of the scaffold. All diameters studied led to axon migration, but in contrast to effects of fiber diameters in other systems, the rate of axon migration was independent of conduit diameter in these templated scaffolds. However, aligned conduits did support more rapid axon migration than non-aligned, tortuous controls.

Article in Press, Oligomers and polymers (film, fabrics) of the linear aromatic polyester poly(trimethylene terephthalate) (PTT) were treated with polyesterases from Thermomyces lanuginosus, Penicillium citrinum, Thermobifida fusca and Fusarium solani pisi. The cutinase from T. fusca was found to release the highest amounts of hydrolysis products from PTT materials and was able to open and hydrolyse a cyclic PTT dimer according to RP-HPLC–UV detection. In contrast, the lipase from T. lanuginosus also showed activity on the PTT fibres and on bis(3-hydroxypropyl) terephthalate (BHPT) but was not able to hydrolyse the polymer film, mono(3-hydroxypropyl) terephthalate (MHPT) nor the cyclic dimer of PTT. As control enzymes inhibited with mercury chloride were used. Surface hydrophilicity changes were investigated with contact angle measurements and the degree of crystallinity changes were determined with DSC.

Polyesters were synthesized from 4′-acetoxyphenyl-4-acetoxybenzoate and dibasic acids having 6–12 methylene units using the transesterification procedure described by van Luyen and Strzelecki. These polymers are designated Sn, where n is the number of methylene units in the diacid. The transition temperatures of our polymers stand in reasonable agreement with those reported by Strzelecki and Liebert. The nematic phase extends over a broad temperature range (70–100°), and the biphasic region spans an additional 50°. The texture of the nematic phase is normal for S7-1 having ηinh = 0.30 dl/g, but the other polymers show bright nematic droplets on a darker background. The density of droplets decreases with increasing ηinh in the S7 series, and as η is increased for the other polymer homologues. Only S7-1 exhibits Williams domains on application of an electric field. Quite different properties are found for the polyester having ηinh = 0.80 dl/g prepared from 4′-hydroxyphenyl-4-hydroxybenzoate and the diacid chloride. It melted sharply 24° higher, and its nematic phase showed a normal texture. Moreover, its nematic-isotropic transition appears in the DSC as a sharp peak, and the biphasic region spans only 9°. We believe the transesterification reaction occasionally involves the internal ester linkage in the monomer unit, producing a polymer with no definite repeating unit structure and a distribution of hard segment lengths.