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In the present work, the texturability of filament yarns produced from recycled bottle grade polyethylene terephthalate (R-PET) and new fiber grade PET (FG-PET) were investigated and compared experimentally. Yarn spun on a spin-draw spinning machine was draw-textured. Elongation at break in each fiber was set to reach 30 ± 5% in the texturing machine. The effect of the draw-texturing conditions on thermomechanical, structural, and crimp properties were examined. Draw-texturing behaviors of the fibers were analyzed using differential scanning calorimetry and measurements of intrinsic viscosity, mechanical and crimp properties, density, and X-ray diffraction. The results indicate that crystallinity of the textured yarn from R- PET and FG-PET has increased compared to the semi-drawn yarns. Further, the lateral dimensions of the R-PET crystals are relatively well developed. Crimp properties show nearly similar response for two polymer yarns for the texturing process. It was found that R-PET can be the premier feed supply for the draw-texturing process and that filaments with appropriate confidence could be obtained from the R-PET.

In this study, side-by-side bicomponent filaments from recycled poly(ethylene) terephthalate (R-PET) from post-consumer bottles, fiber-grade PET (FG-PET) and bottle-grade PET (BG-PET) successfully were extruded. The bicomponent fibers in the forms of FG/R, BG/R and FG/BG were produced in a spinning machine and drawn by a thermal drawing process to improve their mechanical properties using draw ratios between ‘2.5 and 2.8’. The effects of conditions on the fiber structure, physical properties and crimp formation of resultant fibers were evaluated. The birefringence, shrinkage and mechanical properties, such as tensile strength and tensile modulus, increased and elongation at break decreased for the drawn fibers, and this was attributed to the fiber orientation. Distinct crimp formation was observed from drawn bicomponent fibers after thermal treatment. There were significant birefringence and shrinkage difference between two components in drawn bicomponent fibers caused to severe crimp formation.

Side by side bicomponent filament from recycled poly(ethylene) terephthalate from post-consumer bottles and fiber grade PET was extruded. The bicomponent fibers were produced in a melt spinning machine and drawn to improve their mechanical properties. The effects of conditions on the fiber structure and physical properties of resultant fibers were evaluated by the following methods: differential scanning calorimetric (DSC), scanning electron microscopy (SEM), optical microscopy, intrinsic viscosity (IV) and tensile testing. The mechanical properties, such as tensile strength and initial modulus for bicomponent filament showed improvement compared to those for FG-PET. Furthermore, degradation of R-PET molecular structure leads that the viscosities of two polymers are of comparable value.

PLA hollow fibers with different internal diameters were produced as a media for liquid encapsulation via high-speed melt-spinning process, changing important parameters (e.g. material type, polyme...

There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate-polymer nanocomposites containing aerogel with extremely low density, large open pores, and high surface area are also an important class of polymer nanocomposites. Thus, this article provides an overview on the effect of aerogel on mechanical and thermal properties of polymer-based nanocomposites. Moreover, the preparation, history, classification, and characteristics of the aerogel are addressed. Among the polymer-aerogel nanocomposites, various categories including silica and carbon aerogel-polymer nanocomposites were discussed in detail. POLYM. COMPOS., 2017. © 2017 Society of Plastics Engineers

Cellulose has been used as a raw material for the manufacture of membranes and fibers for many years. This review gives the background of the most recent methods of treating or dissolving cellulose, and its derivatives to form polymer films or membranes for a variety of applications. Indeed, some potential applications of bacterial cellulose, nanofibrillar cellulose (NFC) for films showing enhanced barrier characteristics are reviewed as well as the utilization of cellulose nanonocrystals (CNC) for production of highly oriented super strong films or thin films is discussed. Because of the success of the Lyocell process as well as the amine/metal thiocyanate solvent blends of cellulose and other polysaccharides like starch, chitosan, and other natural polymers. Consequently, the use of cellulose (or its derivatives) and another polysaccharide dissolved as a blend is also elaborated. It is our hope that the reader will want to follow up and investigate these new systems and use them to develop end u...

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.

Blend biofibers with relatively high protein content were fabricated from cellulose and soy protein isolate (SPI) using an ethylenediamine–potassium thiocyanate solvent system. Due to the decrease in solution viscosity, the SPI loading was limited to a maximum of 40 %, considering the 100 % draw down ratio applied during fiber coagulation. The results obtained from chemical and X-ray analyses support the formation of interaction through mainly secondary bonding. Increasing the protein content resulted in fibers with slightly improved thermal stability. Electron microscopy images of the fibers revealed a homogeneous dispersion of protein without clear phase separation. The percent crystallinity and the tensile data revealed that the best compatibility was obtained for 20 % SPI ratio and that the fiber exhibited the same birefringence as control fiber. In addition, blending cellulose with protein resulted in fibers with faster biodegradation.

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.

Pure and blend films from chitosan (CH) and soy protein isolate (SPI) were produced in varying compositions (CH/SPI 75/25, 50/50, 25/75 w/w) based on the solvent type (acetic and formic acids). Glycerol was used as a plasticizer. The interactions between the two biopolymers was confirmed by FTIR and TGA, indicating miscibility and compatibility. Increasing the amount of soy protein decreased the tensile strength and absorptive properties, but improved the ability of the film to withstand thermal degradation. Blend films cast using acetic acid gave higher hydrophobicity, better internal blend miscibility, and better tensile properties than blend films cast from formic acid.

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

Cellulose and proteins are potential polymers for developing biodegradable materials for high value-added applications. A combination with these natural polymers could be useful to enhance the properties of final materials and to extend their application areas. In particular, blend biofibers that are degradable and sustainable can be engineered from a mixture of cellulose and proteins, such as soy protein, silk fibroin, collagen, etc. In a binary polymeric blend, the compatibility of cellulose and proteins is influenced by the characteristics of each polymer in the employed solvent system as well as processing conditions. Therefore, utilizing solvents that can dissolve cellulose and proteins, and coagulants that are non-solvents for both polymers is of importance. In this book chapter, the formation and characteristics of blend biofibers from these polymers will be discussed.

Nylon is one of the most important polymers for production of high-performance fibers. High tenacity, high elasticity, good adhesion to rubber, and resistance to heat, abrasion, and chemicals make it possible for nylon filaments/yarns to be used widely in various technical products such as tire cords, industrial threads, climbing ropes, and fishing nets. This chapter first reviews the recent developments in spinning and treatment methods of high-performance nylon fibers. These techniques affect different elements inside the fiber structure, improving the tensile, thermal, and chemical properties. To understand such effects the morphology and the physical and chemical characteristics of the filaments are explained in detail. Finally, this chapter provides some suggestions for future production of technical nylon fibers.

This chapter discusses various polymerization routes for major polyolefins such polyethylenes and polypropylene with emphasis on various catalysts. Ziegler–Natta catalysts as well as newer metallocene catalysts are reviewed. Major industrial polymerization processes are also discussed. This chapter finally describes the most important extrusion methods for polyolefins, which can create a variety of products from processes like melt spinning, film casting, film blowing, injection molding, blow molding, and rotational molding. Melt spinning of polyolefins is described in a great detail.

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

Summary Using the novel ethylenediamine/potassium thiocyanate (ED/KSCN) solvent system developed in our labs, a simpler, environmentally friendlier method was developed to produce membranes using cellulose, proteins, and other polymers. In contrast to current industrial methods that use processes that are relatively expensive with toxic or dangerous solvents, the new system eliminated majority of those concerns. In this study, soy protein concentrate and cellulose was used to develop a nonporous composite membrane with good physical properties. Glutaraldehyde was applied as the crosslinking agent to stabilize the molecular network structure of the blended membranes. Results showed that nonporous membranes were produced that were strong, flexible, and the exposure to the crosslinking agent shown structural and thermal improvement of the network membranes. This resulting blend of biopolymer membranes with improved physical abilities can be useful for food packaging, filtration systems, or even medical applications.

Concerns about health issues and environmental pollution stimulate research to find new health and hygiene related products with healing properties and minimum negative effect on the environment. Development of new, natural antibacterial agents has become one of the most important research areas to combat some pathogens such as Gram- positive and Gram-negative bacteria, fungi, algae, yeast, and some microorganisms which cause serious human infections. Lawsonia Inermis (henna) leaf extracts for preparation of antibacterial poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA) nanofibers via electrospinning technique were investigated. PEO and PVA based electrospun fibers containing henna extract were verified by the appearance of FTIR peaks corresponding to the pure extract. Our study demonstrates that 2.793 wt.% Li in PVA and PEO based solutions showed bactericidal effects against Staphylococcus aureus and bacteriostatic action to Escherichia coli. Concentrations of henna leaf extract strongly impacted antibacterial activities against both bacteria. Henna leaves have a great potential to be used as a source of a potent eco-friendly antimicrobial agent.

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.

Cellulose/collagen biofibers were produced from ethylene diamine/potassium thiocyanate binary solvent system, with methanol as a coagulant. The dynamic viscosity of the solutions decreased with the gradual increase in the collagen content up to 40%. The elemental analysis showed incorporation of collagen into cellulose matrix, thereby demonstrating some degree of interaction with the cellulose matrix. The chemical and thermal analysis further revealed an intermolecular interaction between cellulose and the protein and improved thermal stability, respectively. Furthermore, the electron microscopy images mostly exhibited fibrillar morphology with no visible phase separation, indicating compatibility between the two phases. Moreover, biofibers containing higher cellulose content showed higher crystallinity, tensile, and birefringence properties of the composite fibers.

Durable non-fluorine hydrophobic cotton surfaces were obtained by treating woven cotton fabrics using combinations of silica nanoparticles and multifunctional silanes. Both the hydrophobicity and durability of treated cotton surfaces were controlled by selectively adjusting the alkyl chain length of silane hydrophobes and the surface chemistry, surface area, and content of silica nanoparticles. It was found that with an increase in the alkyl chain length of the silane hydrophobes, the hydrophobicity of treated cotton surfaces increased: the maximum surface durability was obtained at an alkyl chain length of 12 carbon atoms. Hydrophilic silica nanoparticles significantly improved the hydrophobicity and durability of treated cotton surfaces, whereas the hydrophobic silica nanoparticles were found to reduce them. The surface area of the silica nanoparticles did not have a significant impact on the cotton fabric hydrophobicity, however, a larger silica surface area resulted in better durability. The highest h...

β-Cyclodextrin (β-CD) is capable of forming inclusion complexes but cannot form a direct covalent bond with textile materials; hence, some cyclodextrin derivatives have been synthesised with reactive groups to allow them to chemically bind to various substrates. In this study, β-CD was modified with itaconic acid containing carboxyl and vinyl groups because this bifunctional compound can be attached to β-CD via the esterification reaction and because its vinyl group can perform free-radical polymerisation. The synthesised cyclodextrin itaconate was characterised using elemental and thermal analyses, solubility testing and NMR, FTIR and Raman spectroscopy. In addition, the impact of the grafting of this vinyl monomer on the performance of cotton fabric was investigated. The presence of anchored CD nanoparticles on the surface of the fibres was demonstrated by using SEM and FTIR as well as the ability of the attached CDs to form inclusion complexes.

In this study, we investigated the effect of tensile properties of poly(ethylene naphthalate) (PEN) yarns on the ballistic performance of woven and nonwoven soft and composite armors. The results of ballistic tests of PEN armors were compared with Kevlar 49 armors as a reference. Based on these results, the Cunniff's equation was revised by removing the fiber elongation at break to predict the relationship between tensile properties and ballistic performances of PEN fibers. The calculations showed that by increasing tenacity of PEN fibers from 8.5 g/den (commercial product) to 12.5 g/den (strongest up to date PEN fibers produced by a novel melt spinning process discovered by our research group), the weight ratio of PEN to Kevlar 49 decreased from 1.8 to 1.35 with the same ballistic performance. Contrary to the results of the soft armors, composite armors made of high modulus PEN woven fabric showed a 17% lower ballistic resistance compared to the composite armor made of low modulus PEN woven fabric. The results of ballistic tests indicated that high tenacity PEN fibers produced in this research could have potential in soft and composite armors, and high velocity impact applications or improve performance of PEN in its current applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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.

Noncovalently bonded crystalline inclusion compounds (ICs) have been formed by threading host cyclic starches, cyclodextrins (CDs), onto guest nylon-6 (N-6) chains. When excess N-6 is employed, nonstoichiometric (n-s)-N-6-CD-ICs, with partially uncovered and “dangling” N-6 chains, result. While the host crystalline CD lattice is stable to ∼300 °C, the uncovered, yet constrained, portions of the N-6 chains emanating from the CD-IC surfaces may crystallize below or be molten above ∼225 °C. We have been studying the constrained crystallization of the unthreaded N-6 chains “dangling” from (n-s)-N-6-CD-ICs, with comparison to bulk N-6 samples, as functions of N-6 molecular weights, lengths of uncovered N-6 chains (N-6:CD stoichiometry), and the CD host used. In the IC channels formed with host α- and γ-CDs containing 6 and 8 glucose units, respectively, single and pairs of side-by-side N-6 chains are threaded and included. In α-CD-ICs, the ∼0.5 nm channels produced by stacked α-CDs are separated by ∼1.4 nm, wh...

chinese acad sci, ningbo inst mat technol & engn, ningbo 315201, zhejiang, peoples r china.

Hydrophilic fumed silica (SiO 2 )/polyacrylonitrile (PAN) composite electrolyte membranes were prepared by electrospinning composite solutions of SiO 2 and PAN in N,N-dimethylformamide (DMF). Among electrospinning solutions with various SiO 2 contents, the 12 wt% SiO 2 in PAN solution has highest zeta potential (−40.82 mV), and exhibits the best dispersibility of SiO 2 particles. The resultant 12 wt% SiO 2 /PAN nanofiber membrane has the smallest average fiber diameter, highest porosity, and largest specific surface area. In addition, this membrane has a three-dimensional network structure, which is fully interconnected with combined mesopores and macropores because of a good SiO 2 dispersion. Composite electrolyte membranes were prepared by soaking these porous nanofiber membranes in 1 M lithium hexafluorophosphate (LiPF 6 ) in ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1 vol%). It is found that 12 wt% SiO 2 /PAN electrolyte membrane has the highest conductivity (1.1 × 10 −2 S cm −1 ) due to the large liquid electrolyte uptake (about 490%). In addition, the electrochemical performance of composite electrolyte membranes is also improved after the introduction of SiO 2 . For initial cycle, 12 wt% SiO 2 /PAN composite electrolyte membrane delivers the discharge capacity of 139 mAh g −1 as 98% of theoretical value, and still retains a high value of 127 mAh g −1 as 89% at 150th cycle, which is significantly higher that of pure PAN nanofiber-based electrolyte membranes.

Porous nylon-6 fibers are obtained from Lewis acid-base complexation of gallium trichloride (GaCl3) and nylon-6 using electrospinning followed by GaCl3 removal. DSC and FTIR results reveal that the electrospun fibers, prior to GaCl3 removal, are amorphous with no hydrogen bonds present between nylon-6 chains. GaCl3 being a Lewis acid interacts with the Lewis base sites (CdO groups) on the nylon-6 chains, thereby preventing the chains to crystallize via intermolecular hydrogen bonding. Subsequent removal of GaCl3 from the as-spun fibers by soaking the electrospun web in water for 24 h leads to the formation of pores throughout the fibers. While the average fiber diameter remains effectively the same after salt removal, the average surface area increases by more than a factor of 6 for the regenerated fibers. The dual use of a metal salt (Lewis acid) to (a) facilitate fiber formation by temporary removal of polymer interchain interactions and (b) act as a porogen provides a facile approach to obtain porous fibers via electrospinning.

Recently with the availability of monomers for poly(ethylene naphthalate) (PEN) at a large scale and low cost, much attention has been paid to develop PEN fibers, based on their superior mechanical and thermal properties, to compete with the most commercially important poly(ethylene terephthalate) fibers, especially in some performance‐driven markets. In this review, technical papers, product reports, and patents are reviewed to summarize the developments in the production of PEN fibers via melt‐spinning. Mechanical properties of PEN fibers are presented as a function of spinning and drawing parameters. Morphology of PEN fibers are also discussed to understand factors controlling the fiber properties.

In recent years, there has been steady progress in developing new polymers and functional polymer fibers. The objectives of this issue are to provide readers an overview of significant advances for the production of high performance fibers such as Kevlar, PBO, Spectra and Dyneema fibers and to describe new super strong M5 fibers, highly elastic XLA™ fibers and self‐crimping T‐400, T‐800, and other fibers. Additional goals are to present futuristic technologies such as shape memory fibers and compare them with innovative spandex fibers as well as to describe unique nanofibers from biopolymers by using novel electrospinning methods. Finally new, high performance poly(ethylene naphthalate) fibers will be reviewed.

A nylon 6,6 complex with GaCl 3 in nitromethane (4–5 wt% nylon 6,6) was prepared at 50–70 °C over 24 h for the purpose of disrupting the interchain hydrogen bonding between nylon 6,6 chains, resulting in amorphous nylon 6,6, and increasing the draw ratio for improving the performance of nylon 6,6 fibers. After drawing, complexed films and fibers were soaked in water to remove GaCl 3 and regenerate pure nylon 6,6 films and fibers. FTIR, SEM, DSC, TGA, and mechanical properties were used for characterization of the regenerated nylon 6,6 films and fibers. The amorphous complexed nylon 6,6 can be stretched to high draw ratios at low strain rates, due to the absence of hydrogen bonding and crystallinity in these complexed samples. Draw ratios of 7–13 can be achieved for complexed fibers, under low strain rate stretching. This study indicates that nylon 6,6 fibers made from the GaCl 3 complexed state, using a high molecular weight polymer, can reach initial moduli up to 13 GPa, compared to initial moduli of 6 GPa for commercial nylon 6,6 fibers. Lewis acid–base complexation of polyamides provides a way to temporarily suppress hydrogen bonding, potentially increasing orientation while drawing, and following regeneration of hydrogen bonding in the drawn state, to impart higher performance to their fibers.

The photodegradation of isotactic polypropylene (PP) films containing a monoazo pigment and hindered amine light stabilizers (HALS) has been undertaken. PP films were exposed to medium pressure mercury lamp radiation in the laboratory for periods of up to 8 weeks and the degree of degradation (oxidation/deterioration) was examined using FTIR spectroscopy and differential scanning calorimetry (DSC) as well as by measuring changes in the mechanical properties, contact angle, and density. The results of these measurements indicate that unstabilized PP films degraded after only 240-h irradiation. By adding an organic pigment to PP films along with antioxidant and HALS, the photostability of PP films increased to the 1500-h level. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

In the present study, the morphology and mechanical properties of nylon-6 nanofibers were investigated as a function of molecular weight (30,000, 50,000, and 63,000 g/mol) and electrospinning process conditions (solution concentration, voltage, tip-to-collector distance, and flow rate). Scanning electron micrographs (SEM) of nylon-6 nanofibers showed that the diameter of the electrospun fiber increased with increasing molecular weight and solution concentration. An increase in molecular weight increases the density of chain entanglements (in solution) at the same polymer concentration; hence, the minimum concentration to produce nanofibers was lower for the highest molecular weight nylon-6. The morphology of electrospun fibers also depended on tip-to-collector distance and applied voltage concentration of polymer solution as observed from the SEM images. Trends in fiber diameter and diameter distribution are discussed for each processing variable. Mechanical properties of electrospun nonwoven mats showed an increase in tensile strength and modulus as a function of increasing molecular weight. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

High-strength poly(ethylene terephthalate) (PET) fibers were obtained using low molecular weight (LMW) polymervia horizontal isothermal bath (hIB), followed by postdrawing process. We investigated the unique formations of different precursors, which differentiated in its molecular orientation and crystalline structures from traditional high-speed spinning PET fibers. Sharp increase in crystallinity was observed after drawing process even though the fibers showed almost no any crystallinity before the drawing. Properties of as-spun and drawn hIB and control filaments at different process conditions were compared. As would be expected, performances of resulted treated undrawn and drawn fibers have dramatically improved with developing unique morphologies. Tenacities more than 8 g/d for as-spun and 10 g/d for drawn treated fibers after just drawn at 1.279 draw ratio were observed. These performances are considerably higher than that of control fibers. An explanation of structural development of high-strength fibers using LMW polymer spun with hIB is proposed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42747.

Commercial polyesters have been manufactured via condensation polymerization and contain small quantities of small cyclic molecules along with the much higher molecular weight linear chains. The cyclic oligomers create problems during fiber processing, such as spinning and dyeing. Recently the cyclic oligomers and their ring-opening polymerization have become of interest. The cyclic oligomers can be prepared as major products by using high-dilution methods, polymer-supported techniques, and cyclo-depolymerization. The cyclic oligoesters can then be used as feedstock for their ring-opening polymerization. Ring-opening polymerization has some advantages over the conventional polymerization method. The conventional method produces a small molecule by-product, whose removal requires high temperature and high vacuum. The overall reaction is long, varying from 5 to 10 h. On the other hand, ring-opening polymerization does not produce any by-product and the reaction occurs at atmospheric pressure. Furthermore, the process is very rapid. Polyesters like poly(ethylene terephthalate) and poly(butylene terephthalate) have been increasingly used due to their good physical properties. Among these is their ability to act as a gas barrier, so polyester film is widely used as a packaging material. The characteristics of polyesters depend on their structures, symmetries, and conformational features. Polyesters with collinear attachment of ethylene glycol diesters to the phenyl rings, like PET and PBT, allows for flipping of their phenyl rings. However, the phenyl rings in polyesters with non-collinear attachment of ethylene glycol diesters, like poly(ethylene 2,6-naphthalate) and poly(ethylene isophthalate), cannot be flipped. The flipping of phenyl rings may allow gases to permeate, as the gas molecules may use them much like a trap door or valve, so polyesters with non-collinear ethylene glycol diester linkages have improved gas barrier properties.

Poly(trimethylene terephthalate) (PTT) was prepared by the ring-opening polymerization of its cyclic dimer. Antimony(III) oxide, titanium(IV) butoxide, dibutyltin oxide, and titanium(IV) isopropoxide were used as catalysts. Among the catalysts, titanium(IV) butoxide was the most effective for the same reaction conditions. A weight-average molecular weight of 63,500 g/mol was obtained from ring-opening poly merization at 265 °C for 2 h in the presence of 0.5 mol % titanium(IV) butoxide. The PTTs obtained from the polymerization catalyzed with increasing amounts of antimony(III) oxide showed increasing weight-average molecular weights and reaction conversions. When 1 mol % antimony(III) oxide was used, the weight-average molecular weight was 32,000 g/mol and the conversion was 82% after 1 h of polymerization at 265 °C. In the case of the polymer catalyzed by titanium(IV) butoxide under the same conditions, the weight-average molecular weight and conversion were 40,000 g/mol and 77% when 0.25 mol % was used, whereas 0.5 mol % catalyst produced a weight-average molecular weight of 27,000 g/mol and a conversion of 95%. To get an acceptable molecular weight and relatively high reaction conversion, a catalyst concentration of at least 0.5 mol % was found to be necessary, in contrast to conventional condensation polymerizations, which require only about one-tenth of this amount of the catalyst. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6801–6809, 2006

Amorphous poly(ethylene isophthalate) (PEI) was synthesized, and was used for preparing an inclusion compound (IC) with γ-cyclodextrin (γ-CD). Coalesced polymer was produced by washing the PEI-γ-CD-IC with hot water. Wide angle X-ray diffraction, Fourier transform infrared, and differential scanning calorimetry analyses were employed to verify formation of PEI-γ-CD-IC and to compare the as-synthesized and coalesced PEI samples. These observations suggested that the conformations and morphology/chain-packing of PEI were changed via coalescence from its γ-CD inclusion compound. The glass-transition temperature of the amorphous coalesced PEI is 15–20°C higher than the Tg observed for the as-synthesized sample, even when observed in the second heat after cooling from well above Tg at 260°C. The amorphous as-synthesized PEI retains its randomly-coiling structure, while coalesced PEI has at least partially retained, the highly extended and parallel chains from the narrow channels of the inclusion compound, resulting in better/tighter packing among the PEI chains manifested by a higher Tg. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6049–6053, 2006

Super high modulus polyethylene fibers can be created by converting high molecular weight flexible PE chains into highly oriented and extended chain conformations. However, unlike polyethylene, aliphatic polyamides have very high cohesive energy and therefore cannot be easily drawn and highly oriented. This review addresses this fundamental problem by analyzing various novel approaches that can be used to suppress hydrogen bonding in these types of polyamides. Plasticization of such polymers with ammonia, iodine, salts, and Lewis acids, as well as dry spinning, wet spinning, and gel spinning, are discussed. Specialized techniques that involve vibrational zone drawing and annealing as well as laser heating zone drawing and annealing are also reviewed. Some of these methods definitely lead to remarkable improvements in initial modulus and other mechanical properties. The development of recombinant spider silk proteins as well progress in spinning these materials is also reported. The advantages and disadvan...

Investigated in the present study are the physical properties, morphology, and structure of PP/N6 alloy filaments (10, 20 wt % N6) made with or without PP-g-MAH as compatibilizer. The alloy filaments produced at the take-up speeds of 300 and 800 m/min were drawn with draw ratio of 3.5 and 2, respectively. Stress–strain curves of PP and alloy filaments show ductile and brittle behavior, respectively. It is suggested that the brittle behavior of alloy filaments is due to the presence of microvoids or micropores at the interface of PP and N6; these lead to stress concentration and thus to a decrease in tenacity, modulus, and elongation at break. Effects of the blending of N6 with PP on birefringence and crystalline and amorphous orientation factors of the composite filaments are studied. The amorphous orientation factor, fam, of PP was found to increase with an increase in the amount of N6. The alloy filaments behaved like isostrain materials and most of the force in spinning and drawing was born by the PP phase. The presence of N6 fibrils helped to orient PP chain molecules in amorphous regions. However, the crystalline factor, fc, of PP decreased with the increase in nylon fraction. This means the presence of the crystals of N6 caused a decrease in the orientation of the PP crystals. LSCM micrographs of the filament showed the presence of matrix–fibril morphology with the N6 fibrils oriented along the axis. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 532–544, 2005

3-(Trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (AEM 5700) is a trifunctional monomer that can be polymerized under acidic conditions at temperatures greater than 100 °C. Under such conditions, coatings based on AEM 5700 formed on PET substrates are relatively hydrophobic and exhibit rewetting times higher than 100 min. Hydrophilic coatings exhibiting a rewetting time of 2.8 min can be also formed when AEM 5700 is initially hydrolyzed under alkaline conditions and then polymerized under acidic conditions. This effect could be related to the accessibility of unreacted hydroxyl groups and quaternary ammonium groups for interaction with water. Excellent antimicrobial action was demonstrated for all coatings based on AEM 5700 on PET substrates. Polyester fabrics having AEM 5700 coating can be dyed with direct dyes. The loss of hydrophilic properties for AEM 5700 coatings is observed after dyeing with direct dyes.

Polyamide 66 (PA66) has been complexed with the Lewis acid GaCl 3 for the purpose of disrupting the interchain hydrogen bonded network. FTIR and 13 C-NMR observations indicate that Ga metal cations form a 1:1 complex with the carbonyl oxygens of the PA66 amide groups. PA66–GaCl 3 films are amorphous and rubbery with a single relaxation, attributable to the glass transition temperature, at ∼−32 °C and a structure that appears by X-ray diffraction to be thermally stable to at least 200 °C. The complexed films could be drawn at room temperature to draw ratios (DR) up to ∼30, and could then be decomplexed, or regenerated, by soaking in water. GaCl 3 complexation and subsequent regeneration of PA66 was accomplished without changing its molecular weight, and all but ∼5 mol% of the amide groups in the regenerated PA66 were uncomplexed. The undrawn regenerated films regain levels of crystallinity much lower than possessed by the uncomplexed PA66 reference film. However, up to a DR of 8, drawing prior to regeneration increases the crystallinity, reaching crystallinity levels that are high for PA66, that has not been heat treated, and that are almost twice higher than in the uncomplexed (undrawn) reference film. It is intriguing that, in this DR regime, crystallinity increases quite sharply as the film is extended, despite the fact that molecular orientation does not appear to be increasing. For DR>8, the crystallinity decreases, but remains above that of the reference film. The level of crystallinity in PA66 can be controlled over a much wider range by the complexation-drawing-regeneration process than by conventional drawing processes.

Poly(ethylene isophthalate) (PEI) was synthesized for this research with essentially a condensation polymerization of isophthalic acid and ethylene glycol catalyzed by zinc acetate and antimony trioxide. Several samples were obtained, and their characteristics were observed and compared with poly(ethylene terephthalate) (PET). The synthesized PEI samples were chemically identified by 1H NMR. Thermal analysis with differential scanning calorimetry (DSC) yielded results that indicate the samples were primarily amorphous, with a glass-transition temperature of 55–60 °C. Molecular weights of these PEI samples were also obtained through intrinsic viscosity measurements (Mark–Houwink equation). Molecular weights varied with conditions of the polymerization, and the highest molecular weight achieved was 21,000 g/mol. Finally, the diffusion coefficient, solubility, and permeability of CO2 gas in PEI were measured and found to be substantially lower than in PET, as anticipated from their isomeric chemical structures. This is because in PET the phenyl rings are substituted in the para (1,4) positions, which allows for their facile flipping, effectively permitting gases to pass through. However, the meta-substituted phenyl rings in PEI do not permit such ring flipping, and thus PEI may be more suitable for barrier applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4247–4254, 2004

Polypropylene fibres which can be conventionally dyeable using disperse dyes have been prepared by alloying with nylon 6 and a polypropylene grafted maleic anhydride compatibiliser during extrusion. The dyeing performance of fibres containing various amounts of these components has been assessed.

Ternary blends of polypropylene (PP), nylon 6 (N6) and polypropylene grafted with maleic anhydride (PP/N6/PP-g-MAH) as compatibilizer with up to 50 wt% of N6 were investigated. PP-g-MAH content was varied from 2.5 to 10%. Blends of the two polymers PP/N6 (80/20) without the compatibilizer were also prepared using an internal batch mixer and studied. The ternary blends showed different rheological properties at low and high shear rates. The difference depended on the amount of N6 dispersed phase. Co-continuous morphology was observed for the blend containing 50% N6. This blend also exhibited higher viscosity at low shear rate and lower viscosity at high shear rates than the value calculated by the simple rule of mixture. At higher shear rates, viscosity was lower than that given by the rule of mixture for all blend ratios. An increase in viscosity was observed in the 80/20 PP/N6 blend after the concentration of the interfacial agent (PP-g-MAH) was increased. Polyblends containing up to 30% N6 could be successfully melt spun into fibers. DSC results showed that dispersed and matrix phases in the fiber maintained crystallinity comparable to or better than the corresponding values found in the neat fibers. The dispersed phase was found to contain fibrils. By using SEM and LSCM analyses we were able to show that the N6 droplets coalesced during melt spinning which led to the development of fibrillar morphology.

The purpose of this study was to investigate the effects of reaction media, composition, and temperature on the rate of the alkaline depolymerization of poly(trimethylene terephthalate) (PTT). The alkaline depolymerization of PTT was carried out at 160–190°C in ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), ethylene glycol monobutyl ether (EGMBE), diethylene glycol monoethyl ether (DEGMEE), and a mixture of these solvents. During the reaction, PTT was quantitatively converted to disodium terephthalate and 1,3-propanediol. The alkaline depolymerization reaction rate constants were calculated based on the concentration of sodium carboxylate, which was equivalent to the molar amount of sodium hydroxide. The depolymerization rate of PTT was increased by increasing the reaction temperature and by adding ethereal solvents. Moreover, the depolymerization rate was significantly accelerated in the order of EG < DEG < TEG < EGMBE < DEGMEE. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 99–107, 2001

Polypropylene is a leading commercial, fiber-forming polymer due to its low cost and potential for making high strength fibers. As the polymer of choice in the biomedical field, polypropylene contains only two elements, namely carbon and hydrogen. As a result, it is very hydrophobic and bio-inert lacking biodegradability in the landfill. Meltblown and spunbond polypropylene nonwovens were exposed to γ-radiation doses up to 25 kGy. The changes in morphology, chemical, thermal, and tensile properties were characterized by various analytical techniques. Following γ-radiation, the FTIR spectrum illustrated an increase in carbonyl groups suggesting radio-oxidation. Additionally, there was a decrease in thermal and tensile properties indicating deterioration of the polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39917.

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.