Structures and flammability properties of polyethylene terephthalate(PET) fibers containing encapsulated carbon materials

In this paper, carbon nanotubes (CNTs) and carbon microspheres (CMSs) have been microencapsulated to obtain microencapsulated carbon nanotubes (MCNTs) and microencapsulated carbon microspheres (MCMSs). Moreover, a series of PET fibers with CNTs/CMSs or MCNTs/MCMSs were prepared by melt spinning. Morphologic structures, mechanical, thermal, and flame retardant properties of MCNTs/MCMSs /PET fibers have been studied by TEM, SEM, electronic tension meter, DSC, TG, limiting oxygen index (LOI), and vertical flammability instruments. The results show that the tensile strength of MCNTs/MCMSs/PET fibers are increased because of better dispersion and compatibility of MCNTs/MCMSs in PET and enhanced orientation degrees of fibers, compared with CNTs/CMSs/PET fibers. Moreover, the highest values of mechanical properties are observed with 0.4 wt% content. Meanwhile, the MCNTs/MCMSs/PET fibers have good thermal stabilities and their fabrics have higher LOI value of 25.3%, reaching B1 class of China standard GB 17591-2006. Overall, this method endowed the MCNTs/MCMSs/PET fibers with the good mechanical and flame-retardant properties.     

Numerical simulation of heat transfer in protective clothing with various heat exposure distances

This paper reports on a model of heat transfer through multi-layer firefighter protective clothing with an air gap under radiant heat flux of 8.5 kW/m². The model considers the dynamical changes of heat exposure distance due to human body movement. The predictive results were found in good agreement with the experimental measurements. Numerical model was employed to study the effects of heat exposure distance and moving speed on heat transfer in multi-layer fabric system. The results showed that the heat exposure distance had an significant impact on skin burn. The safe zones for firefighting operation were more than 0.3 m for 2nd degree burn and 0.15 m for 3rd degree burn when the fabric system was exposed to 8.5 kW/m² for 300 s. However, the moving speed could speed up the time to 2nd degree burn but alleviate the time to 3rd degree burn.     

Preparation and characterization of electrically semi-conductive polyfuran-coated poly(ethylene terephthalate) fibers

One of the most important textile materials, poly(ethylene terephthalate) (PET) fiber, was coated with a semi-conductive polyfuran (PFu) by in situ oxidative polymerization using FeCl₃ oxidant in solvent mixture of acetonitrile–chloroform. The effects of polymerization conditions such as volume ratios of acetonitrile/chloroform, monomer concentration, and oxidant/monomer mol ratio were investigated on PFu content (%) of the composites. It was observed that pretreatment of PET in dichloromethane increased PFu content and its coating continuity before polymerization. The highest PFu content (12.0%) was obtained using FeCl₃/furan mol ratios of 3.5 in acetonitrile/chloroform mixture (5/1). The density values of the composites with different PFu contents were measured. Composite fibers were also subjected to doping processes with HCl and I₂ vapors, separately, and it was observed that the surface resistivity of PFu/PET (10¹² Ω/cm²) reached to 53 Ω/cm² after doping with I₂. The structural, thermal, and morphological characterization was performed with FTIR, XRD, TGA, and SEM, respectively.     

Mechanical Behavior of Ensete ventricosum Fiber Under Tension Loading

The mechanical behavior of Ensete ventricosum fibers, expressed as the dependency of tension force in relation to the elongation, was determined for fibers with gauge length 50 mm and transformed into general linear mathematical model describing dependency of tension stress and strain. The average rupture force (10.88 ± 1.11) N, rupture stress (390.33 ± 21.96) MPa, rupture strain (0.021 ± 2 · 10^–5), and volume energy (3.39 ± 0.22) J m^?3 were also determined at this conducted study. Using image analyses, it was determined that the cross section of Ensete ventricosum fiber has circle shape and its dimension was specified. From the study, it implies that Ensete ventricosum fiber, with respect to its mechanical behavior under tension loading having regard to its density and to the fact that it is environmentally friendly, biodegradable and recyclable, could be used as a perspective construction material of the future. Determined model of mechanical behavior could be applied as background for further research focused on the Ensete fiber application.     

Characterization of New Natural Cellulosic Fiber from Heteropogon Contortus Plant

Natural fibers are one of effective substitute for switching artificial fiber and concentrating to reinforce polymer matrixes due to their decomposable character. This study was implied to realize physico-chemical properties of bio fiber obtained from Heteropogon contortus (HC) plant. Heteropogon contortus fibers (HCFs) had cellulose (64.87 wt. %), hemicellulose (19.34 wt. %), lignin (13.56 wt. %), and low density (602 kg/m³). The chemical functional group of HCFs was established by Fourier transform infrared spectroscopy, thermal stability of the fiber up to 220°C discovered by thermogravimetric analysis. Further the assets of HCFs proved that it can act as an excellent reinforcement material as a bio composite. Finally, the tensile properties were carried out through single fiber tensile tests, such as tensile strength, tensile modulus and microfibrillar angle.     

Characterization of Thermal Properties of Pig Hair Fiber

Hair fiber is a key by-product of humane slaughter of pigs with considerable economic value. In the present study, we investigated the thermal properties of pig hair fiber using Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA). The DSC curve showed a broad endotherm (around 50–80°C) initially, followed by denaturation doublet peaks (229°C and 239°C) and finally a pyrolysis endotherm. The melting enthalpy of pig hair fiber was 9.93 J/g on dry basis. During TGA, distinct phases of initial weight loss due to loss of moisture and later through thermal degradation of protein around 238–240°C were observed. Mean thermal insulation and conductivity values of pig hair fiber were 0.068 ± 0.004 m²K/W and 0.029 ± 0.003 W/m/K, respectively. The thermal characteristics of pig hair fiber were similar to other keratin fibers of animal origin.     

Physicochemical Properties of New Cellulosic Fibers from Azadirachta indica Plant

This research study was aimed at examining newly identified natural fiber from the bark of Azadirachta indica (AI). The various properties were analyzed and compared with other available bark fibers. The chemical composition of Azadirachta indica fibers (AIFs), high cellulose (68.42 wt.%) content, and low lignin (13.58 wt.%) were discovered. The lower density of 740 kg/m³, and crystallinity index of 65.04% properties were identified. The maximum peak temperature obtained was 321.2 °C in Differential thermogravimetry (DTG) curve. Taken together, all the properties of AIFs indicated that they could be suitable to make green composites for various types of applications.     

Characterization of New Natural Cellulosic Fiber from the Bark of Dichrostachys Cinerea

The increasing environmental awareness has directed attention of the researchers towards the field of natural fiber composites. The aim of this investigation is to understand the physico-chemical properties of fibers extracted from the bark of the Dichrostachys Cinerea (DC) plant. Dichrostachys Cinerea fibers (DCFs) has cellulose (72.4 wt. %), hemicellulose (13.08 wt. %), lignin (16.89 wt. %), density (1240 kg/m³), crystallinity index (57.82%), and tensile strength (873 ± 14 MPa). Besides the cellulose degradation of DCFs at 359.3° vide by the thermo-gravimetric analysis and chemical groups are identified by Fourier transform analysis. Eventually the characterization results of DCFs strongly show the possibility of reinforcement in polymer matrices.     

Improving the flame retardancy of PET fiber by constructing the carbon microspheres based melamine polyphosphate powder

Abstract

Carbon microspheres (CMSs) as carbon source, melamine phosphate (MP) as acid source and gas source, the integrated CMSs based MP composites (SiMP-CMSs) was in-situ prepared to improve the flame retardancy of PET fiber. A series of SiMP-CMSs/PET fiber were prepared by the melt spinning method. By investigating the thermal stability, flame retardancy, flame-retardant mode, crystallization and orientation degree of PET composite fiber, the results showed that, with the addition of 0.9?wt% SiMP-CMSs, the LOI value and vertical combustion grade of SiMP-CMSs/PET composite fiber was 27.4% and B1 level. The main flame-retardant mode of SiMP-CMSs/PET fiber was 31.33% physical barrier, 36.04% flame inhibition and 11.12% catalytic charring. The thermal decomposition temperature was delayed, and the residual amount increased from 11.34% to 16.13%. With the accelerated crystallization rate and the increased grain orientation, the aggregated structure of SiMP-CMSs/PET fiber was also optimized.     

Extraction and Characterization of New Natural Cellulosic Chloris barbata Fiber

Natural swollen finger grass fibers being novel are botanically known as “Chloris barbata fibers (CBFs)” and are selected for this study in order to understand their morphological properties. The CBF has higher cellulose (65.37 wt%) content and lower density (634 kg/m³). Crystallinity Index (CI) of CBF was calculated from X-ray diffraction studies and is valued as 50.29%. The surface of CBF was examined using a Scanning Electron Microscope (SEM) for observing the surface morphology. Structural characterization and Chemical functional group were confirmed by Fourier transform infrared spectroscopy (FT-IR). The thermal behavior of CBFs was determined using TG and DTG curves from Thermo gravimetric (TG) analysis. Findings show that the fiber has a semi-elongated nearly circular cross-sectional shape, the fiber diameter is between 180 and 200 μm. TG analysis revealed that these fibers are thermally stable until 210°C. Thus the characterization results confirm the possibility of using CBF for the manufacture of sustainable fiber reinforced polymer composite.     

Optimization of chemical activation of cotton fabrics for activated carbon fabrics production using response surface methodology

Abstract

The preparation of activated carbon fabric (ACF) from cotton fabric treated with phosphoric acid (H₃PO₄) was optimized using the response surface methodology (RSM). Experimental activation variables including; impregnation ratio, heating rate, activation temperature, and activation time were optimized based on the responses evaluated (adsorption capacity, yield of the produced ACF). The operation conditions for obtaining the ACFs with the highest the adsorption capacity and process yield were proposed. Optimized conditions were: impregnation ratio of 2, heating rate of 7.5 °C min^?1, the activation temperature of 500 °C, and the activation time of 30 min. The ACFs produced under optimized conditions were characterized by scanning electron microscopy (SEM), X-ray energy dispersion spectroscopy (EDX). The surface area and pore volume of carbon nanostructures were characterized by nitrogen adsorption isotherm at 77 °K using BET method. The obtained results showed that the produced ACFs have developed porous structure, fabric shape, BET surface area (690 m²/g) and total pore volume (0.3216 cm³/g), and well-preserved fibers integrity.     

Manufacturing and properties of ultra-low density fiberboards with an unsaturated polyester resin by a dry process

Although ultra-low density fiberboards (ULDFs) have good sound and thermal insulation performance, formaldehyde emission in the manufacturing process and in the subsequent use of the products limits their field of application. The objective of this study was to employ an unsaturated polyester resin (UPR) in the manufacturing of the boards as a substitute of formaldehyde-based adhesives in order to develop environment-friendly ULDFs. The effects of UPR dosage, fiber treatment agent, press time and fiber consumption on the properties of fiberboards were studied. Sound absorption and thermal conductivity were also measured to ensure sound and thermal insulation properties of the fiberboards. Board density, modulus of rupture and thickness swelling in 2 h were 320 kg/m³, 4.14 MPa and 3.75%, respectively, under optimal conditions such as 12% UPR dosage, 1% fiber treatment agent, 400 g fiber consumption and 210 s press time. Noise reduction coefficient and thermal conductivity of the boards were found within a range of 0.68–0.58 and 0.038–0.048 W/(m K), respectively, while the density of boards ranged from 150 to 400 kg/m³. Therefore, sound absorption property of the fiberboards developed in this study satisfies the requirement of high-efficiency sound absorption materials, which is close to the value (0.67) of ULDF having a density of 56.3 kg/m³ obtained by a wet process. Thermal insulation property of boards was close to that of commonly used insulation materials such as rock wool [0.036 W/(m K)] and glass fiber [0.045 W/(m K)]. In conclusion, fiberboards can be used for non-structural furniture materials, sound and thermal insulation materials in buildings because of their environmental friendliness, good mechanical properties, and excellent sound and thermal insulation properties.     

Modified Rice Straw as a Template in Syntheses of Nano TiO2 Loaded on Wool Fibers for Wastewater Treatment

Industrialization of textile produces large amounts of colored wastewater and recycling of that wastewater is recently under the scope. The current work is implemented to use rice straw as a template for preparation of nano TiO₂ to be applied in decolorization of wastewater of textile industries. Different treatments including silica removal and esterification were performed for rice straw to produce highly reactive nanotitanium dioxide. Size, morphological shape, and surface area of the so obtained TiO₂ nanoparticles were observed to be influenced by rice straw treatments. Percentage of anatase phase in titanium dioxide was increased from 41.6% to 75.0% after removing of silica and modification with citric acid of rice straw. The particle size of anatase was significantly reduced from 88.6 nm to 10.5 nm while the BET surface area of nanotitanium dioxide was enlarged from 41.2 m²/g to 84.7 m²/g. The prepared TiO₂ nanoparticles were loaded onto wool fibers and the photocatalytic properties of nano TiO₂ powder before and after loaded to fiber were measured against methylene blue dye. The dye removal percentage raised from 92.5 to 99.2 by using of nano TiO₂ powder-loaded wool fibers compared to nano TiO₂ powder.     

Density profile and microstructural analysis of densified beech wood (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.) plasticized by microwave treatment

This study was carried out in order to determine the efficacy of microwave (MW) plasticization for wood densification purposes. The plasticization process was carried out using a continuous feed laboratory MW at a frequency of 2.45 GHz. European beech (Fagus sylvatica L.) specimens measuring 50 mm?×?40 mm?×?8 mm were MW treated (plasticized) with an output of 3.5 kW at a conveyor speed of 0.4 m/min. Afterwards, MW plasticized specimens were densified with a ratio of 50%. Microscopic structure changes of densified wood were detected using a scanning electron microscope (SEM) and density profiles were measured using the X-ray densitography. An average density of 677 kg m^?3 and 771 kg m^?3 increased significantly to 951 kg m^?3 for radially densified and to 1194 kg m^?3 for tangentially densified specimens. X-ray densitography results show uniformity of density profiles through specimen thickness, which confirmed the evenly plasticized volume of wood. Microscopic structure observation revealed that the MW plasticization was not accompanied by any fractures, and deformations present in the densified wood were due to viscoelastic buckling of cell walls without crack propagation. Therefore, MW treatment can be considered as an effective method for wood plasticization.     

分子内阻燃PET纤维的结构性能

 以反应性无卤阻燃剂CEPPA为第三单体,通过共聚改性制备了分子内阻燃PET树脂,并经熔融纺丝纺制阻燃PET纤维。利用元素分析和核磁共振分析了阻燃PET树脂中的磷含量,结果表明大部分CEPPA聚合到PET分子链中。对阻燃PET纤维结晶性能、染色行为、力学性能及燃烧性能也进行了研究,结果表明阻燃PET纤维的结晶度随着磷含量的增加而降低,这导致了纤维染色性能的提高。阻燃PET纤维采用分散染料在常压沸染条件下上染率可达90%以上。此外纤维具有优异的阻燃性能,极限氧指数(LOI)值约为35%,并且抗熔滴性能得到了改善.     

Wood–water relations of chestnut wood used for structural purposes

Hygroscopic properties and water vapour permeability of chestnut (Castanea sativa Mill.) wood were studied using saturated salt solutions, and the results were analyzed using the Hailwood–Horrobin model. At 20 °C/65 % the equilibrium moisture content (MC _eq ) and density were 11.5 ± 0.1 % and 576.6 ± 10.2 kg m^?3, respectively, and the fiber saturation point was 20.83 %. The average water vapour permeability was 0.320 kg m^?1 s^?1 Pa^?110⁸, lower than that of Radiata pine (0.726 kg m^?1 s^?1 Pa^?110⁸). Furthermore, there was no difference in permeability between tangential and radial cuts. This low permeability is explained by the scant development of the multilayer of the Hailwood–Horrobin model. This is attributed to the wood extractives, which reduce the void space and hindered condensation. Chestnut wood has different vapour sorption and vapour permeability than conifers normally used in construction.     

Preparation of microencapsulated carbon microspheres coated by magnesium hydroxide/polyethylene terephthalate flame–retardant functional fibers and its flame retardant properties

In order to improve the compatibility between the flame retardants of carbon microspheres coated by magnesium hydroxide (MH@CMSs) and the PET matrix and improve the spinnability of the masterbatch, MH@CMSs have been microencapsulated by PET to obtain microencapsulated carbon microspheres coated by magnesium hydroxide flame retardants – MMH@CMSs.Morphologies and structures of MMH@CMSs have been studied by scanning electron microscope (SEM), transmission electron microscopy (TEM), and FTIR, which showed that an organic shell layer of PET as capsule wall was coated on the surface of MH@CMSs. A series of MMH@CMSs/PET fibers with different MMH@CMSs contents were successfully prepared through the melt-spinning method. The morphology and structure of MMH@CMSs/PET fibers were characterized by SEM and FTIR. The flame retardancy of MMH@CMSs/PET fibers was determined via limiting oxygen index (LOI) test and cone calorimeter. Results showed that the MMH@CMSs/PET fibers possessed optimum flame retardancy when the MMH@CMSs content is 0.6 wt.%, at which the LOI reached a maximum of 25.8, and the pk-HRR, total heat release, and total smoke release were reduced by 27.4, 20, and 13.6%, compared with pure PET fibers, respectively. Moreover, the flame-retardant mechanism was studied by thermogravimetric analysis, thermogravimetric analysis-infrared spectrometry, and the SEM of the residue char, which disclosed that MMH@CMSs enhanced the thermal stability of PET fibers, and promoted PET fibers to form a dense and continuous protective char layer that effectively blocked heat transfer and combustible gas release.     

Physical Characterisation of an Alginate/Lysozyme Nano-Laminate Coating and Its Evaluation on ‘Coalho’ Cheese Shelf Life

This work aimed at the characterisation of a nano-laminate coating produced by the layer-by-layer methodology and its evaluation on the preservation of ‘Coalho’ cheese. Initially, five alternate layers of alginate and lysozyme were assembled in an aminolysed/charged polyethylene terephthalate (A/C PET) and physically characterised by UV/VIS spectroscopy, contact angle, water vapour (WVTR) and oxygen (OTR) transmission rates and scanning electron microscopy. Afterwards, the same methodology was used to apply the nano-laminate coating in ‘Coalho’ cheese and its shelf life was evaluated during 20 days in terms of mass loss, pH, lipid peroxidation, titratable acidity and microbial count. UV/VIS spectroscopy and contact angle analyses confirmed the layers’ deposition and the successful assembly of nano-laminate coating on A/C PET surface. The coating presented WVTR and OTR values of 1.03?×?10^?3 and 1.28?×?10^?4 g m^?2 s^?1, respectively. After 20 days, coated cheese showed lower values of mass loss, pH, lipidic peroxidation, microorganisms’ proliferation and higher titratable acidity in comparison with uncoated cheese. These results suggest that gas barrier and antibacterial properties of alginate/lysozyme nanocoating can be used to extend the shelf life of ‘Coalho’ cheese.     

A new study on characterization of Pithecellobium dulce fiber as composite reinforcement for light-weight applications

ABSTRACT

A bio-fiber, Pithecellobium dulce is abundantly available in all over the world. It has a higher cellulose content (75.15 ± 0.26 wt.%) and low density (865 ± 26 kg/m³). To acquire fundamental knowledge about Pithecellobium dulce Fibers (PDFs), its physicochemical, crystalline, tensile, and morphological properties were examined and compared with other plant fibers. The chemical functional groups and crystallinity index (49.2 ± 2.45%) of the PDFs were obtained via Fourier transform-infrared analysis and X-ray diffraction, respectively. The Thermogravimetric analysis results of PDFs exhibit thermal stability up to 170°C. The surface morphology of PDF was analyzed by scanning electron microscopy. The attained results conclude that PDFs are appropriate fibers for acting as reinforcement in manufacturing of green composite product.