Isothermal crystallization behavior of PAR/PBT composite prepared by island-in-a-sea fiber method

The PAR fiber reinforced PBT composite was manufactured using the PAR/PBT island-in-a-sea fiber. The isothermal crystallization kinetics of the PAR/PBT composite and the neat PBT resin were investigated in the temperature range of 187–199 °C. To calculate the Avrami parameters for analyzing the crystallization behavior, crystallization peaks were measured and analyzed in terms of the crystallization temperature and the inclusion of the PAR fiber. The crystallization rate of the PBT is faster than that of the PAR/PBT composite from the analysis of their relative crystallinity. Consequently, it is considered that the PAR fiber interrupted the crystal nucleation and growth of the PBT matrix. It can be confirmed with the crystallization half time and the crystalline morphologies at the chosen isothermal temperatures.     

Preparation and crystallization behavior of polylactide nanocomposites reinforced with POSS-modified montmorillonite

We herein report the preparation and crystallization behavior of polylactide (PLA) nanocomposites reinforced with polyhedral oligomeric silsesquioxane-modified montmorillonite (POSS-MMT), which is prepared by exchanging sodium cations of pristine sodium montmorillonite (Na-MMT) with protonated aminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS-NH₃ ⁺). PLA nanocomposites with 1–10 wt% POSS-MMT contents are manufactured via melt-compounding, and their structures and melt-crystallization behavior are investigated. It is characterized that POSS-MMT nanoparticles in the nanocomposites have an exfoliated structure of MMT silicates with POSS-NH₃ ⁺ and partial POSS-NH₂ crystals. DSC cooling thermograms suggest that the overall melt-crystallization rates of the nanocomposite with only 3 wt% POSS-MMT are remarkably enhanced in comparison with the neat PLA. From the isothermal crystallization analysis based on the Avrami model, the overall melt-crystallization of PLA/POSS-MMT nanocomposites is found to be dominated by the heterogeneous nucleation and three-dimensional spherulite growth. Isothermal melt-crystallization experiments using a polarized optical microscope show that the spherulite nucleation density of PLA/POSS-MMT nanocomposites is much higher than that of the neat PLA, whereas the spherulite growth rates of all the nanocomposites are almost identical with the rate of the neat PLA. It is concluded that the highly enhanced melt-crystallization rates of PLA/POSS-MMT nanocomposites stem from the dominant nucleation effect of POSS-MMT nanoparticles for PLA crystals.     

Polyelectrolyte multilayer coated nanofibrous mats: Controlled surface morphology and cell culture

We reported the controlled surface morphologies and the cell culture of polyelectrolyte multilayer coated nylon 6 fibrous mats with different number of layers. Polyelectrolyte multilayer coated nylon 6 fibers were successfully prepared by an alternative deposition of alginic acid sodium salt and chitosan via a Layer-by-Layer (LbL) electrostatic self-assembly. The surface morphology, stiffness, and hydrophilicity of polyelectrolyte multilayer coated nylon 6 fibrous mats could be finely tuned by regulating the number of polyelectrolyte nanocoating. It was observed that the morphology of polyelectrolyte multilayer coated nylon 6 fibers was uniform and smooth, indicating a dense and harder nanocoating of polyelectrolytes onto nylon 6 fibers. Compared to pure nylon 6 fibrous mat (tensile strength ～10.6±1 MPa), the tensile strength of polyelectrolyte coated nylon 6 fibrous mats was largely increased to 35.2±2 MPa for 5 bilayers coated fiber mats. In addition, it was found that at an initial stage after 1 day of cell culturing, the electrospun nylon 6 fibrous mats coated with 5 bilayer of alginic acid and chitosan show the highest cell affinity (good adhesion), while the electrospun nylon 6 fibrous mats coated with 10 bilayer show the lowest cell affinity. After cell seeding for 3 days, it was observed that rate of proliferation is enhanced by increasing the number of bilayer up to 3 bilayers (good proliferation), and then drastically decreased with further increasing the number of bilayer.     

Dyeing properties of mixture of ultrafine nylon and polyurethane with different types of dye

The dyeing and color fastness properties of levelling type acid dye, milling type acid dye, metal complex dye and reactive dye on ultrafine nylon, polyurethane fiber/film and their mixtures were investigated. Ultrafine nylon was dyed well with four types of dye at pH 3-6, but levelling type acid dye showed low washing fastness. Amine-rich polyurethane fiber exhibited enhanced dyeability due to amino groups which acted as dyeing sites, compared to regular polyurethane fiber. In simultaneous dyeing with milling type acid dye and metal complex dye, amine-rich polyurethane fiber absorbed more dye molecules than ultrafine nylon, the color difference between two fibers were apparent. Polyurethane-impregnated ultrafine nylon was also prepared and its build-up properties were determined. It was found that polyurethane whose soft segment was composed of polytetramethylene glycol (PTMG) and polypropylene glycol (PPG) showed improved dyeing property and subsequently high color strength.     

Effects of Chemical Functionalization of MWCNTs on the Structural and Physical Properties of Elastomeric Copolyetherester-based Composite Fibers

Elastomeric copolyetherester (CPEE)-based composite fibers incorporating various neat and functionalized multiwalled carbon nanotubes (MWCNTs) were prepared through a conventional wet-spinning and coagulation process. The influence of functionalized MWCNTs on the morphological features, and the thermal, mechanical properties and electrical conductivity of CPEE/MWCNT (80/20, w/w) composite fibers were investigated. FE-SEM images show that a composite fiber containing poly(ethylene glycol)-functionalized MWCNTs (MWCNT-PEG) has a relatively smooth surface owing to the good dispersion of MWCNT-PEGs within the fiber, whereas composite fibers including pristine MWCNTs (p-MWCNT), acid-functionalized MWCNTs (a-MWCNT), and ethylene glycol-modified MWCNTs (MWCNT-EG) have quite a rough surface morphology owing to the presence of MWCNT aggregates. As a result, the CPEE/MWCNT-PEG composite fiber exhibits noticeably increased thermal and tensile mechanical properties as well as a faster crystallization behavior, which stems from an enhanced interfacial interaction between the CPEE matrix and MWCNT-PEGs.     

Crystallization and Luminescence Properties of Polypropylene Fiber Containing Rare Earth Aluminates and a Sorbital Derivative Nucleating Agent

Polypropylene (PP) fibers with a sorbital derivative nucleating agent (SDN) and rare earth aluminates (SrAl₂O₄:Eu²⁺,Dy³⁺) were prepared via melt compounding and melt-spinning. Non-isothermal crystallization kinetics and luminescence properties of PP and luminous PP fibers were studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and decay of the afterglow test. The crystallization temperature determined by DSC increased with the addition of the nucleating agent during the cooling process from 200 °C. The Jeziorny model successfully described the non-isothermal crystallization behavior of the luminous PP with various SDN contents. The crystal grain size and morphology of the sample with the SDN was different from that without nucleating agent. The luminous PP fabric having high initial brightness intensity, approximately 461 mcd g^-1m^-2, can be prepared with addition of 10 wt% of rare earth aluminates and 0.5 % of SDN.     

Processing and characterization of nickel-plated PBO fiber with improved interfacial properties

A new application of conventional electroless nickel plating to improve the interfacial properties of PBO fibers was reported. The relationship between surface morphology and interfacial properties of nickel-plated PBO fiber was explored. The continuous nickel coating consisted of nickel and phosphorus elements determined by Energy dispersive spectrometer (EDS) and transmission electron microscope (TEM), exhibiting high adhesive durability. The influence of bath temperature and plating time on the crystal structure, microstructure and mechanical properties of nickel-plated PBO fibers was systematically investigated. X-ray diffractometer (XRD) results revealed that the crystal structure among nickel-plated PBO fibers did not show differences. Scanning electron microscope (SEM) and Atomic force microscope (AFM) images showed that the process parameters had a great influence on surface morphology and roughness of nickel-plated PBO fibers, which could directly affect the interfacial properties of nickel-plated PBO fibers. Single fiber pull-out testing results indicated that the interfacial shear strength (IFSS) of PBO fibers after electroless nickel plating had a significant improvement, which reached maximum at 85 °C for 20 min. Single fiber tensile strength of nickel-plated PBO fibers was slightly lower than that of untreated one. Thermo gravimetric analysis (TGA) indicated that nickel-plated PBO fiber had excellent thermal stability.     

Surface modified ployacrylonitrile nanofibers and application for metal ions chelation

Ployacrylonitrile (PAN) nanofibers were formed by electrospinning. Amidoxime ployacrylonitrile (AOPAN) nanofibers were prepared by reaction with hydroxylamine hydrochloride, which were used as the matrix for metal ions chelation. FTIR spectra of the PAN nanofibers and AOPAN nanofibers were recorded for analysis of the surface chemical structures. The AOPAN conventional fibers were also prepared for comparison, and surface morphologies of the modified PAN conventional fibers and PAN nanofibers were observed by FESEM. Metal ions concentrations were calculated by AAS. The chelated isothermal process and kinetics parameters of the modified PAN nanofibers and PAN conventional fibers were studied in this work. Results indicated that the saturated coordinate capacity of AOPAN nanofibers to Cu²⁺, Cd²⁺ was 3.4482 and 4.5408 mmol/g (dry fiber) respectively, nearly two times higher than that of AOPAN conventional fibers. Besides, the desorption rate of Cu²⁺ and Cd²⁺ from metal chelated AOPAN nanofibers was 87 and 92 % respectively in 1 mol/l nitric acid solution for 60 min. The isothermal processes were found to be in conformity with Langmuir model.     

Preparation and characterization of (POSS/TiO2)n multi-coatings based on PBO fiber surface for improvement of UV resistance

The application of poly (p-phenylene-2, 6-benzobisoxazole) (PBO) fiber as reinforcement in composite material was restricted by its photo-degradation, therefore, some measures should be considered to protect PBO fiber against UV aging. In this study, A series of multilayer coating for (POSS/TiO₂)_n was prepared on PBO fiber surface via LbL assembly technique for enhancement of UV resistance. TiO₂ as UV absorbing material was used to relieve UV-degradation of PBO. Surface elemental composition, surface morphology, mechanical and interfacial properties, and UV resistance of uncoated and coated PBO fibers were investigated. These experimental results show multilayer coating of (POSS/TiO₂)_n was uniform deposition on fiber surface after treatment, tensile strength decreased to certain extent, interfacial shear strength increased in a small range and UV resistance is obvious enhanced. After the same accelerated aging time under UV irradiation, the retention of tensile strength and intrinsic viscosity of coated PBO fibers were much better than that of untreated PBO fibers.     

Mechanical and thermal properties of recycled poly(ethylene terephthalate) reinforced newspaper fiber composites

This study presents the mechanical and thermal properties of environment-friendly composites made from recycled newspaper fibers reinforced recycled poly(ethylene terephthalate) (rPET) resin with the addition of styrene-ethylene-butylene-styrene grafted maleic anhydride (SEBS-g-MA) as compatibilizer. The effect of SEBS-g-MA addition (i.e., 10 phr) by using a twin-screw extruder to the rPET resin, followed by different fiber content (5, 10 and 15 wt.%) on the tensile, flexural and impact properties of the composites were determined. Stiffness of composites increased significantly compared to those of rPET/SEBS-g-MA blend. Fiber addition resulted in moderate increases in both tensile and flexural strength of the composites. Scanning electron microscope (SEM) photomicrographs of the impact fracture surfaces demonstrate good adhesion at 5 and 10 % fiber content. Differential scanning calorimetry (DSC) showed that the presence of newspaper fibers enhanced the nonisothermal crystallization kinetics and crystallinity. Thermal stability of the composites was improved as indicated by thermogravimetric analysis (TGA).     

Effect of surface treatment on the structure and properties of para-aramid fibers by phosphoric acid

The surface of para-aramid fiber was modified by phosphoric acid solutions (H3PO4) based on an orthogonal experimental design and analysis method. Statistical results indicate that treatment temperature is the most significant variable in the modification processing, while treatment time was the least important factor. The structure and morphology of the modified fiber were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction instrument (XRD), and scanning electron microscope (SEM). The results showed that some polar groups were introduced into the molecular structure of aramid fibers and the physical structure of the treated fibers was not etched obviously. The interfacial properties of aramid fiber/epoxy composites were investigated by the single fiber pull-out test (SFP), and the mechanical properties of aramid fibers were investigated by the tensile strength test. The results showed that the interfacial shear strength (IFSS) of aramid/epoxy composites was remarkably improved and the breaking strength of aramid fibers was not affected appreciably after surface modification.     

Thiazole based disperse dyes for nylon and polyester fibers

Nine disperse dyes have been synthesized by diazotization of 2-amino-4-(p-nitrophenyl)-5-nitrothiazole and coupled to substituted N-alkylanilines. Spectral properties in the IR and visible range of the dyes obtained were investigated. The dyeing performance of these dyes was assessed on nylon and polyester fibers. These dyes were found to give reddish brown to bluish violet shades on dyeing with very good depth, brightness and levelness on nylon and polyester fibers. The dyed fibers showed fairly good light fastness, very good to excellent fastness to wash, rubbing, perspiration and excellent fastness to sublimation. The dyebath exhaustion and fixation on the fiber were found to be very good.     

Structure and properties of syndiotactic polystyrene fibers prepared in high-speed melt spinning process

High-speed melt spinning of syndiotactic polystyrene was carried out using high and low molecular weight polymers, HMs-PS and LMs-PS, at the throughput rates of 3 and 6 g/min. The effect of take-up velocity on the structure and properties of as-spun fibers was investigated. Wide angle X-ray diffraction (WAXD) patterns of the as-spun fibers revealed that the orientation-induced crystallization started to occur at the take-up velocities of 2–3 km/min. The crystal modification wasα-form. Birefringence of as-spun fibers showed negative value, and the absolute value of birefringence increased with an increase in the take-up velocity. The cold crystallization temperature analyzed through the differential scanning calorimetry (DSC) decreased with an increase in the take-up velocity in the low speed region, whereas as the melting temperature increased after the on-set of orientation-induced crystallization. It was found that the fiber structure development proceeded from lower take-up velocities when the spinning conditions of higher molecular weight and lower throughput rate were adopted. The highest tensile modulus of 6.5 GPa was obtained for the fibers prepared at the spinning conditions of LMs-PS, 6 g/min and 5 km/min, whereas the highest tensile strength of 160 MPa was obtained for the HMs-PS fibers at the take-up velocity of 2 km/min. Elongation at break of as-spun fibers showed an abrupt increase, which was regarded as the brittle-ductile transition, in the low speed region, and subsequently decreased with an increase in the take-up velocity. There was a universal relation between the thermal and mechanical properties of as-spun fibers and the birefringence of as-spun fibers when the fibers were still amorphous. The orientation-induced crystallization was found to start when the birefringence reached — 0.02. After the starting of the orientation-induced crystallization, thermal and mechanical properties of as-spun fibers with similar level of birefringence varied significantly depending on the processing conditions.     

Improved interfacial properties of carbon fiber/unsaturated polyester composites through coating polyhedral oligomeric silsesquioxane on carbon fiber surface

Carbon fibers were coated with E51 plus Methacryl-POSS together in an attempt to improve the interfacial properties between carbon fibers and unsaturated polyester resins matrix. Atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were performed to characterize the changes of carbon fiber surface. AFM results show that the coating of E51 plus POSS significantly increased the carbon fiber surface roughness. XPS indicates that silicon containing functional groups obviously increased after modification. Dynamic mechanical analysis was carried out to investigate the surface energy of carbon fiber. Force modulation atomic force microscopy (FMAFM) and Interlaminar shear strength (ILSS) were used to characterize the interfacial properties of the composites. ILSS was increased by 21.9 % after treatment.     

Effect of collector temperature and conductivity on the chain conformation of nylon 6 electrospun nanofibers

Electrospinning is a versatile process used to prepare micro- and nano- sized fibers from various polymer solution. Here, we dealt with the variation in the morphology of nylon 6 electrospun nanofibers and their polymorphism depending on the type and physical state of the collectors. SEM study showed that the fiber diameter was increased from 80 to 103 nm while it was collected in water bath. Similarly the fiber diameter and bonding was increased 103 to 115 nm with the temperature whereas it was linearly decreased 103 to 90 nm with the conductivity of the water bath. Spectroscopic analysis (FT-Raman, FT-IR) showed that the polymorphism of nylon 6 depended on the types of collector (aluminum sheet and water bath). Nylon 6 electrospun nanofibers display theγ-phase while collected in aluminum sheet andα-phase while collection in water bath. The extent of transformation fromγ- toα-phase was linearly increased with temperature and conductivity of the water bath.     

Effect of surface treatment of jute fibers on the interfacial adhesion in poly(lactic acid)/jute fiber biocomposites

Jute fibers have immense potential to be used as natural fillers in polymeric matrices to prepare biocomposites. In the present study jute fibers were surface treated using two methods: i) alkali (NaOH) and ii) alkali followed by silane (NaOH+Silane) separately. Effects of surface treatments on jute fibers surface were characterized using fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) analyses. Further, the effects of surface treatments on jute fibers properties such as crystallinity index, thermal stability, and tensile properties were analyzed by X-ray diffraction method (XRD), thermo gravimetric analysis (TGA), and single fiber tensile test respectively. The effects of surface treatment of jute fibers on interphase adhesion between of poly(lactic acid) (PLA) and jute fibers were analyzed by performing single fiber pull-out test and was examined in terms of interfacial shear strength (IFSS) and critical fiber length.     

Inherently Flame Retardant Nylon 6 Nanocomposite Fibers

In this study, inherently flame retardant nanocomposite nylon 6 fibers infused with nanoclay and intumescent additives were compounded and melt-spun. Two approaches were adopted to mitigate the loss of mechanical properties typically observed nanocomposite fiber systems: (a) additive particle size reduction; and (b) elastomer toughening of the nanocomposite system. As a result, the ductility of the FR nanocomposite formulations was improved significantly. Structural and morphological characterization of the melt-spun fibers using TEM and XRD demonstrated good dispersion of the additives and exfoliation of the nanoclay platelets. Microscale Combustion Calorimetry analysis demonstrated effective reduction of heat release capacity and thus significant enhancement of flame retardant performance of the compounded fibers.     

硅烷处理对Henequen纤维／PHBV树脂可生物降解复合材料界面粘结性能的影响

本文通过对Henequen纤维表面进行硅烷化改性，使得纤维与树脂间存在化学键合，提高了Henequen纤维与聚羟基丁酸与戍酸酯（PHBV）树脂复合材料界面剪切强度。Henequen纤维/PHBV复合材料界面剪切强度的大小用微粘结法（Microbond)测试，结果表明纤维经硅烷处理后可使界面剪切强度从未处理情况下的5.05Mpa提高6.34Mpa。     

Crystallization behaviour of PP and carbon nanofibre blends

Crystallization behaviour of blends of different MFI isotactic polypropylenes (PP), and blends of PP with carbon nanofibre have been investigated by DSC and polarizing optical microscope. Both higher MFI PP component and the carbon nanofibre in the blend influence the nucleation activity of the melt during non-isothermal crystallization. In presence of carbon nanofibre, the sherulitic growth rate is highly disturbed. The calculation of nucleation activity indicates that carbon nanofibres act as active substrate for heterogeneous nucleation.     

Effects of nanoclay and short nylon fiber on morphology and mechanical properties of nanocomposites based on NR/SBR

Natural rubber and styrene butadiene rubber (NR/SBR) reinforced with both short nylon fibers and nanoclay (Cloisite 15A) nanocomposites were prepared in an internal and a two roll-mill mixer by a three-step mixing process. The effects of fiber loading and different loading of nanoclay (1, 3 and 5 wt. %) were studied on the microstructure and mechanical properties of the nanocomposites. The adhesion between the fiber and the matrix was improved by the addition of a dry bonding system consisting of resorcinol, hexamethylene tetramine and hydrated silica (HRH). This silicate clay layers was used in place of hydrated silica in a HRH bonding system for SBR/NR-short nylon fiber composite. Nanoclay was also used as a reinforcing filler in the matrix-short fiber hybrid composite. The cure and scorch times of the composites decreased while cure rate increased when the short fiber and nanoclay were added. The mechanical properties of the composites showed improvement in both longitudinal and transverse directions with increasing short fiber and nanoclay content. The structure of the nanocomposites was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM). X-ray diffraction results of nanocomposites indicated that the interlayer distance of silicate layers increased. The mechanical properties of nanocomposites (tensile, hardness and tear strength) are examined and the outcome of these results is discussed in this paper.