Final Degradation Temperature Research Articles

Thermal Degradation of Natural Rubber Vulcanizates Reinforced with Organomodified Kaolin Intercalates

In this study, Natural Rubber Vulcanizates (NRV) reinforced with organomodified kaolin was developed. The NRV were subjected to thermal degradation to ascertain its suitability for high-temperature automotive applications. Kaolin intercalation was achieved using derivatives of Rubber seed oil (Hevea brasiliensis) and Tea seed oil (Camellia sinensis) in the presence of hydrazine hydrate as co-intercalate. The developed Natural Rubber Vulcanizates were characterised using Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FTIR) Spectroscopy and Scanning Electron Microscopy (SEM). FTIR spectra obtained for the organomodified natural rubber vulcanizates revealed the presence of carbonyl groups at bands 1564cm-1 and 1553cm-1 which is an indication of organomodified kaolin intercalation within the Natural Rubber matrix for kaolin intercalates of Rubber seed oil and Tea seed oil respectively while no value was reported for the Natural Rubber vulcanizates obtained from the pristine kaolin filler. TGA results indicated that NRV developed from kaolin intercalates of Rubber seed oil (RSO) with onset degradation and final degradation temperatures of 354.2°C and 601.3°C were found to be the most thermally stable of the Natural Rubber Vulcanizates investigated. The SEM micrograph revealed that the kaolin nanofillers in Rubber Seed Oil modified Natural Rubber Vulcanizates were well dispersed as compared to that of Tea Seed Oil modified Natural Rubber Vulcanizates.

Dynamic-Mechanical and Decomposition Properties of Flax/Basalt Hybrid Laminates Based on an Epoxidized Linseed Oil Polymer.

This contribution focuses on the development of flax and flax/basalt hybrid reinforced composites based on epoxidized linseed oil (ELO) resin, exploiting the feasibility of different ratios of glutaric anhydride (GA) to maleinized linseed oil (MLO) in the hardener system (50:0, 40:10 and 30:20 wt.%) to provide crosslinked thermosets with balanced properties. The hybrid laminates have been manufactured by resin transfer molding (RTM) and subjected to dynamic–mechanical (DMA) and thermal gravimetry (TGA) analysis. The presence of glutaric anhydride (GA) resulted in hard and relatively brittle flax and flax/basalt laminates, whose loss moduli decreased as the number of basalt plies diminished. Furthermore, the increase in MLO content in the GA:MLO hardener system shifted the glass transition temperatures (Tg) from 70 °C to 59 and 56 °C, which is representative of a decrease in brittleness of the crosslinked resin. All samples exhibited two stages of their decomposition process irrespective of the MLO content. The latter influenced the residual mass content that increased with the increase of the MLO wt.% from 10 to 30 wt.%, with shifts of the final degradation temperatures from 410 °C to 425 °C and 445 °C, respectively.

Thermogravimetric Analysis of Densified Coco Peat Briquettes

The present work deals with the investigation of thermal decomposition of densified coco peat briquettes using the thermogravimetry method to elucidate the effect of finite size of the biomass briquette on the decomposition profile. The cylindrical samples are varied in term of its density and its shape (sphericity). The sample is heated in a nitrogen atmosphere at different heating rates, ranging from 5°C/min to 20°C/min. The TG curves show three distinct phases of decomposition, i.e. preheating and drying, devolatilization, and char reduction. For all samples, thermal decomposition shifts to higher temperatures with the increase in the heating rate. From the TG curves, it is shown that the initial degradation temperature varies from 181°C to 302°C and the final degradation temperature varies from 328°C to 608°C. The shift to higher temperatures is also observed for the less dense briquettes. The shape of the briquettes affects also the decomposition profile. The less spherical (less of contact area) sample will decompose at higher temperatures. From the DTG curves, it can be seen that the maximum thermal degradation rate takes place at varying temperature ranging from 243°C to 419°C. The peak temperatures depend on the heating rate. However, the density and the shape of the biomass have no appreciable effect on the peak temperature.

Photocatalytic degradation of dyes using one-step synthesized silica nanoparticles

Schematic route diagram of one step synthesis of Silica nanoparticles. • Synthesis of silicon oxide based employing sol–gel method. • Degradation of dye methylene blue and methyl orange. Silica nanoparticles are synthesized by one step simple, rapid and cost effective sol–gel method using methyltrimethoxysilane (MTMS) as precursor. Synthesized silica nanoparticles are characterized by UV–Visible spectroscopic techniques, XRD and FE-SEM. From UV curve the maximum absorbance observed was at the wavelength 297 nm which indicates formation of silica nanoparticles. The FE-SEM analysis showed the larger size of nanoparticles is due to agglomeration of silica nanoparticles. The X-ray diffraction pattern indicate the structure of the silica nanoparticles. FT-IR spectra of silica nanoparticles are indicative of the stretching vibration of Si-O-Si bonds and Si-OH vibration respectively. TGA indicates the final degradation temperature of silica nanoparticles are near about 515 °C temperature. Photo degradation process is carried out by employing different dyes along with UV irradiating at pH-7. Photodegradation of both (10 ppm) methylene blue and methyl orange with 1.5 g/dm 3 SiO 2 photocatalyst dose accomplished around 98 and 95% degradation in 90 min at 25 °C with pH-7. Finally, it can be concluded that silica nanoparticles support to the photo degradation of methylene blue and methyl orange. Hence nanoparticles synthesized using sol–gel method can be used for degradation of various industrial pollutants dyes.

Xanthate-modified silica as a novel multifunctional additive for properties improvement of natural rubber

Reinforcing agents and accelerators are the most important auxiliaries for rubber industry. In this paper, ceric ammonium nitrate (CAN), for the first time, worked as a catalyst for hydroxyl groups in silica to prepare silica grafted sodium xanthate (SSX), which was used as an in-situ modified multifunctional rubber additive in this work. Compared with sodium isobutyl xanthate (SIBX), SSX has enhanced the initial and final degradation temperatures, achieving the improvement of 103 °C and 277 °C, respectively. Notably, owing to the powerful interaction between each component, SSX can be homogeneously dispersed in the natural rubber (NR) matrix in contrast to the seriously aggregated silica. Meanwhile, NR/SSX composites exhibited superior curing properties and showed an increase of 29.1% and 33.4% in the tensile strength and tear strength, respectively, compared to that of traditional 2-mercaptobenzothiazole (MBT) system. Since high-performance rubber composites can be obtained by introducing SSX, we believe that this work can provide a novel and facile approach to prepare natural silicate minerals-based vulcanization accelerators.

Preparation of nanocapsules of palmitic acid with silica shells and their use as a phase change material within microcellular polyurethane foams

A new nanoencapsulated phase change material (PCM) filled polyurethane microcellular foams is reported in this work. Palmitic acid nanocapsules with silica shells (PA@SiO2) is a well-known phase change material synthesized by the sol-gel process are loaded at selected weight ratios into microcellular polyurethane foam. FT-IR spectra revealed successful PA@SiO2 nanocapsules formation and FE-SEM images showed successful core-shell formation with spherical shapes with a mean diameter approximately 350 nm. TGA thermograms showed superior heat resistivity of prepared PCM in comparison with pristine palmitic acid at the final degradation temperature. DSC thermograms showed the heat storage potential of prepared nanoencapsulated PCM as well as corresponding polyurethane nanocomposites. The polyurethane nanocomposites characterized by FT-IR, TGA, FE-SEM as well as DSC methods and data interpreted in detail in order to evaluate the thermal storage capabilities of newly developed nanocomposites.

Characterization of benzoyl treated sugar palm/glass fibre hybrid composites

This paper studies the influence of glass fibre addition and benzoylation treatment on the physical, mechanical and thermal properties of sugar palm composites. Glass fibre (GF) was added in various fibre ratios: 30%, 50% and 70%, related to the amount of sugar palm fibre (SPF). The results obtained revealed that the EP/30TSPF/70 G F composites exhibited the best tensile properties by increasing the tensile strength by 55.7%. For thermal analysis, the results show that EP/TSPF/GF composites had the most improvement in the initial and final degradation temperature. It can be concluded that, benzoylation treatment help improves the adhesion of the SPF to the GF and to the epoxy matrix. Glass fibre addition helps enhanced the characteristics of the SPF composites as the GF overcome the weakness of SPF. This hybrid composites show promising characteristics to be applied for non-structural application as example food tray table.

A Thermoplastic Polyurethane /Nanosilica Composite via Melt Mixing Process and its Properties

This investigation reports the preparation and properties of thermoplastic polyurethane/silica nanocomposite prepared via melt mixing process. In this case, nanosilica at different loading was mixed with a polyester-based thermoplastic polyurethane (TPU). The dispersion of nanofiller was studied by the SEM and TEM analyses. The nanocomposite with optimal dispersion of nanofiller has better filler-polymer interaction that has been confirmed by the FT-IR study. TPU with 1 phr of nanosilica loading showed better tensile properties. DSC study revealed that incorporation of fumed silica in the TPU matrix does not substantially affect the refinement of TPU crystallite, and thus resulted in an insignificant change in glass transition temperature (Tg) and crystalline melting temperature of the nanocomposite. TGA study also confirmed enhanced onset degradation temperature and maximum degradation temperature (Tmax) for optimal nanosilica composite. The final degradation temperature and char content also increased with an increase in fumed silica content. Water contact angle (WCA) study revealed that hydrophilicity of the nanocomposite increased with the incorporation of fumed silica.

An experimental and theoretical mechanistic analysis of thermal degradation of polypropylene/polylactic acid/clay nanocomposites

Polypropylene/polylactic acid (PP/PLA) blends containing 5 wt% of nanoclay in presence and absence of an ethylene‐butylacrylate‐glycidyl methacrylate terpolymer as compatibilizer were prepared by melt‐mixing process. A matrix‐droplet–type morphology confirmed by transmission electron microscope (TEM) and scanning electron microscopy (SEM) studies is formed in presence and absence of the compatibilizer in which the clay platelets were mainly localized in the polylactic acid (PLA) dispersed phase. Degradation studies by means of thermogravimetry analysis (TGA) and analysis of degradation activation energy (Ea), Tmax (maximum degradation temperature), and ΔT (difference between initial and final degradation temperatures) parameters for each polymer component of the system revealed that incorporation of less stable PLA phase to polypropylene (PP) decreases Ea and Tmax parameters, and hence, reduces the thermal stability of PP phase, while incorporation of clay nanoplatelets to the neat blend further reduces its thermal stability attributed to their lack of localization in PP phase. Compatibilization of the filled system results in migration of clay nanoplatelets toward PP and improves Ea and Tmax of PP phase. On the other hand, the Ea and Tmax of PLA phase of the blend were increased with incorporation of clay and its localization within that phase, while compatibilization of the filled system slightly reduces thermal stability of PLA phase due to migration of clay toward PP. A correlation was found between Ea and intensity of the thermogravimetry analysis Fourier‐transform infrared spectroscopy (TGA‐FTIR) peaks of the evolved products. Using the Criado method, a detailed analysis on degradation mechanism of each component was performed, and the changes in the degradation mechanism of the developed systems were determined.

Impact of ZnO Nanoparticles on Thermal Properties of Poly(3-hydroxybutyrate-co-10 mol % 3-hydroxyhexanoate) Copolymer

Biopolymer composites using poly(3-hydroxybutyrate-co-10 mol % 3-hydroxyhexanoate) (P(3HB-co-10 mol % 3HHx)) and ZnO nanoparticles (NPs) were prepared by solution casting method and the effect of ZnO NPs on thermal properties of the prepared biopolymer composites (P(3HB-co-10 mol % 3HHx)/ZnO NPs) were studied using DSC, TGA, GPC, and thermal conductivity analyzer. DSC analysis revealed the dual melting behavior of both neat P(3HB-co-10 mol % 3HHx) and its composites. It also showed that the incorporation of ZnO NPs into P(3HB-co-10 mol % 3HHx) decreased the melting temperature Tm, but increased the melting enthalpy ΔHm and degree of crystallinity Xc of the composites. Compared to neat P(3HB-co-10 mol % 3HHx), the initial degradation temperature T99 of the prepared composites was decreased and vice versa for final degradation temperature due to the addition of ZnO NPs which was revealed from TGA results. The observed thermal conductivity value of neat P(3HB-co-10 mol % 3HHx) and its composites were in between ~5.6 × 10–2 and ~7.9 × 10–2 W m/K with the very high value noticed for 30% ZnO NPs reinforced P(3HB-co-10 mol % 3HHx) composites. Overall P(3HB-co-10 mol % 3HHx)/ZnO NPs composites exhibited high thermal diffusivity and thermal effusivity compared to neat P(3HB-co-10 mol % 3HHx) with very high value noted for 30% ZnO NPs and 5% ZnO NPs reinforced P(3HB-co-10 mol % 3HHx) composites respectively which is essential for thermal related applications.

Phosphorus-containing reactive agent for UV-curable flame-retardant wood coating

An attempt to develop a phosphorus-based flame-retardant UV-curable agent (UV-RA) for coating application led to the synthesis of a reactive compound which can be used as crosslinker along with UV-curable epoxy acrylate oligomer to form a coating. UV-RA was characterized via FTIR, NMR, hydroxyl, and iodine values. Study based on the effects of varying amount of UV-RA incorporated in the formulation was investigated by checking thermal, mechanical, and flame-retardant properties. An enhancement in all the properties was observed with an increase in concentration of UV-RA and each coating containing UV-RA successfully portrayed flame-retardant properties. The highest loss on ignition (LOI) value obtained was 27 while the initial and final degradation temperatures increased along with the char yield. The mechanical properties did not vary much except for the low values for 20UV-RA.

Development of novel bio-based epoxides from microalgae Nannochloropsis gaditana lipids

The objective of this research was to investigate the development of novel bio-based epoxides from microalgae Nannochloropsis gaditana lipids, which were extracted using hexane, petroleum ether and methanol:chloroform (2:1 v/v). In lipids epoxidation, conversions of 90.9%, 99.3% and 87.6% of epoxidized microalgae lipids (EML) were obtained for lipids extracted using these solvents. The mechanical properties of EML in blends with bisphenol A diglycidyl ether (DGEBA) show that the elongation at break increases and tensile strength decreases. Moreover, an increasing in the final maximum degradation temperature and a decrease in the glass transition temperature (Tg) were observed in the blends.

Ammonium zeolite and ammonium phosphate applied as fire retardants for microcrystalline cellulose filled thermoplastic composites

In this study, mechanical, thermal, fire and morphological properties of thermoplastic composites filled with fire retardants (FRs) and microcrystalline cellulose (MCC) were investigated in detail. The composites were produced through the extrusion + injection molding methods using MCC, FRs and high density polyethylene (HDPE). Based on the composites dry-weights, 10%wt. of mono ammonium phosphate (MAP), ammonium zeolite (AZ) or natural zeolite (NZ) were incorporated into polymer matrix for improving reaction of fire of the composites, and their effects on technological properties were evaluated. MAP had a positive effect on tensile and flexural moduli of the composites whilst tensile strength, elongation at break and impact strength properties of the composites were decreased. The highest tensile and flexural strength values were obtained from HDPE/MCC/AZ samples, respectively, 22.13 MPa and 29.93 MPa. The minimum value for impact strength was obtained from HDPE/MCC/MAP5/AZ5 composite (1.68 kJ/m2) whereas the maximum value for impact strengths were achieved from control HDPE composite (5.15 kJ/m2) and HDPE/MAP10 (3.30 kJ/m2). Flexural strength and flexural modulus values of all HDPE composites were higher than the requirement by the ASTM D 6662 standard for polyolefin based plastic lumber decking boards. As the MCC content increased, the initial, maximum and final degradation temperatures of HDPE composites have not been influenced greatly. Thermogravimetric and differential scanning calorimetry analyses showed that the maximum rate weight loss temperature and the crystalline features of HDPE have not been significantly influenced by addition of MCC. Limiting Oxygen Index (LOI) level and charring increased when FRs were incorporated into polymer matrix. In addition, the burning rates of HDPE/MAP10 and HDPE/MCC/MAP5/AZ5 composite were slowed down by 64% and 62%, respectively. It was found that no burning in HDPE/MCC/MAP10 was observed composite during the horizontal burning test. Especially; HDPE/MCC/MAP samples can be used for building products because they meet the CC1 (plastic materials that have a burning extent of 25 mm or less where tested at a nominal thickness of 1.5 mm, or in the thickness intended for use, in accordance with ASTM D 635) class requirements of international building code which means a model building code improved by the International Code Council. In the light of obtained results, it was specified that use of FRs improved morphological, thermal and reaction of fire of the MCC filled HDPE composites.

Perforative silica microsphere-modified phenolphthalein-based poly(arylene ether sulfone) composites: tensile and thermal properties

Perforative silica microspheres (PSMs) were prepared by an emulsion method coupled with sol–gel technology and phase separation. Next, phenolphthalein-based poly(arylene ether sulfone)/PSM composites (PES-C/PSM) were fabricated. PSM was characterized by scanning electron microscopy (SEM) and the Brunauer–Emmett–Teller (BET) method. The as-synthesized PSM exhibited a spherical shape with an external diameter of 2–10 µm, surface area of 166.5 m2/g and pore volume of 1.35 cm3/g. SEM and energy-dispersive spectroscopy (energy-dispersive spectroscopy) were used to characterize the morphology and the composition of the composite, respectively. Both SEM and energy-dispersive spectroscopy results revealed that the PES-C polymer chains penetrated into the PSM pores. In addition, the effect of PSM weight content on the mechanical properties and thermal stability of the composites was characterized by tensile tests and thermal analysis, respectively. A 19% increase in tensile strength and a 29% increase in breaking elongation of PES-C were achieved by the addition of 0.50 wt% PSM. Moreover, the thermal oxidative stability of PES-C was remarkably improved with the incorporation of PSM. Compared with pristine PES-C, the final degradation temperature was enhanced by 42 °C at 1.0 wt% PSM loading. Our studies have indicated that PSM is a kind of promising reinforcement for improvement of tensile and thermal properties of engineering plastics.

INFLUENCE OF NANOFILLER ON THERMAL DEGRADATION RESISTANCE OF HYDROGENATED NITRILE BUTADIENE RUBBER

ABSTRACT Studies on the degradation of elastomers and their prevention have become increasingly important in recent years because of stringent environmental conditions in many industrial applications. The reactive atomistic simulation was executed on a hydrogenated acrylonitrile-butadiene rubber (HNBR40) model compound composed of 40 monomer units. The reactive simulation was used to study the decomposition behavior of HNBR40, to visualize different pyrolysis products, and also to analyze the degradation mechanism of HNBR40. Ethylene, propylene, and acrylonitrile were observed as dominant products at lower temperature, and 1-butene was found at higher temperature. Pyrolysis–gas chromatography–mass spectrometry was used to verify the decomposition products obtained from the prediction of atomistic simulation. In this study, nanofillers, especially nanoclays and nanosilicas, were used to prevent degradation significantly. Restricted degradation by the nanofiller-reinforced rubber prolonged the durability. Furthermore, the reactive simulation was performed to understand thermal decomposition characteristics of the model compound in the presence of the nanofiller. The initial decomposition temperature, the final degradation temperature, and the rate of degradation improved to a great extent on the addition of the model nanosilica compound as obtained from the simulation studies. Moreover, the lifetime of nanoclay- and nanosilica-reinforced hydrogenated acrylonitrile–butadiene rubber was calculated by using thermogravimetric analysis, and its useful lifetime was compared with that of the pristine polymer in the application temperature range of 150 °C.

Non-isothermal degradation kinetics of virgin linear low density polyethylene (LLDPE) and biodegradable polymer blends

The thermal degradation kinetics of several polymers, including biodegradable blends were investigated in non-isothermal thermogravimetry using several analytical methods. Virgin linear low density polyethylene (LLDPE) and LLDPE blends with polystarch-N (PSN), a prodegradant starch additive material used in 20 and 40 wt%., were investigated to determine the degradation behaviour of such materials in pyrolysis conditions. The results were compared to those obtained with virgin low (LDPE) and high density polyethylene (HDPE). An analytical solution model was also developed to assess the two degradation steps of the biodegradable blends which enabled the assessment of the apparent activation energy (Ea) of each material in the blend on its own based on the initial and final degradation temperatures. It was observed that the thermal behaviour and Ea value didn’t change significantly with the increase of biodegradable prodegradant, which shows that biodegradable blends can be treated with similar conditions regardless of the content of the biodegradable masterbatch present in the blend.

Reactive molecular dynamics simulation for analysis of thermal decomposition of oligomeric polyacrylicester model nanocomposite and its experimental verification

Molecular dynamics simulation was performed for the first time on oligomeric poly(ethylene-co-ethylacrylate-co-n-butylacrylate) (ACM) chains, consisting of ten repeating monomer units in presence and absence of model silica particle to investigate the influence of nanosilica on high-temperature degradation characteristics of ACM nanocomposite. The initial decomposition temperature and the final degradation temperature were increased while the rate of degradation of ACM decreased with the introduction of silica molecules. Alkyl radicals, alkenes and carbon dioxide as the dominant products were detected during the reactive simulation. Other small molecular products including carbon monoxide and alkoxy radicals were discovered in the eventual products as well. Furthermore, pyrolysis gas chromatography-mass spectrometry (py-GC-MS) was used to identify the decomposition products obtained from the degradation of ACM at high temperature and the results were compared with the prediction from atomistic modelling. The activation energy of degradation for ACM was also calculated from the reactive simulation as well as from the thermogravimetric analysis and gel permeation chromatography (GPC). The results of the ReaxFF molecular dynamics simulations were consistent with all the experimental observations. The current study would help in understanding and improve the thermal stability of various polymers in industrial applications.

Nanocomposites containing polyvinyl alcohol and reinforced carbon-based nanofiller: A super effective biologically active material.

A new class of biologically active polymer nanocomposites based on polyvinyl alcohol and reinforced mixed graphene/carbon nanotube as carbon-based nanofillers with a general abbreviation (polyvinyl alcohol/mixed graphene–carbon nanotubes) has been successfully synthesized by an efficient solution mixing method with the help of ultrasonic radiation. Mixed graphene and carbon nanotubes ratio has been prepared (50%:50%) wt by wt. Different loading of mixed graphene–carbon nanotubes (2, 5, 10, 15, and 20 wt%) were added to the host polyvinyl alcohol polymer. In this study, polyvinyl alcohol/mixed graphene–carbon nanotubesa–e nanocomposites were characterized and analyzed by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, and the thermal stability was measured by thermogravimetric analysis and derivative thermal gravimetric. Fourier transform infrared and X-ray diffraction spectra proved the addition of mixed graphene–carbon nanotubes into polyvinyl alcohol matrix. X-ray diffraction patterns for these nanocomposites showed 2θ = 19.35° and 40° due to the crystal nature of polyvinyl alcohol in addition to 2θ = 26.5° which attributed to the graphite plane of carbon-based nanofillers. Thermal stability of polyvinyl alcohol/mixed graphene–carbon nanotubes nanocomposites was enhanced comparing with pure polyvinyl alcohol. The main degradation step ranged between 360° and 450°C. Moreover, maximum composite degradation temperature has appeared at range from 285°C to 267°C and final composite degradation temperature (FCDT) displayed at a temperature range of 469–491°C. Antibacterial property of polyvinyl alcohol/mixed graphene–carbon nanotubesa–e nanocomposites were tested against Escherichia coli bacteria using the colony forming units technique. Results showed an improvement of antibacterial property. The rate percentages of polyvinyl alcohol/mixed graphene–carbon nanotubesb, polyvinyl alcohol/mixed graphene–carbon nanotubesc, and polyvinyl alcohol/mixed graphene–carbon nanotubesd nanocomposites after 24 h are 6%, 5%, and 7% respectively. However, polyvinyl alcohol/mixed graphene–carbon nanotubese nanocomposite showed hyperactivity, where its reduction percentage remarkably raised up to 100% which is the highest inhibition rate percentage. In addition, polyvinyl alcohol and polyvinyl alcohol/graphene–carbon nanotubesa–d showed colony forming units values/ml 70 × 106 and 65 ± 2 × 106 after 12 h. After 24 h, the colony forming units values/ml were in the range of 86 × 106–95 × 106.

Influence of Single-Walled Carbon Nanotubes on the Performance of Poly(Azomethine-Ether) Composite Materials

ABSTRACTThe present work is aimed to fabricate a new set of composite materials containing conducting poly(azomethine-ether) reinforced with single-walled carbon nanotubes in the form of single-walled carbon nanotube/poly(azomethine-ether)1–5 for excellent enhanced thermal as well as conducting behavior of poly(azomethine-ether). Single-walled carbon nanotubes of variable loading have been embedded into conducting poly(azomethine-ether) using in situ polymerization technique. Before attempting the polymerization, 1,3-thiazole established poly(azomethine-ether) and its conformable monomers have been prepared and their chemical structures have been correlated by spectral analyses. Furthermore, ηinh and Mw values for poly(azomethine-ether) were found 0.89 dL g−1 and 39723.6, respectively. The fabricated single-walled carbon nanotube/poly(azomethine-ether)1–5 composites were specified and characterized by wide-angle X-ray diffraction patterns, Fourier transform infrared spectroscopy, thermal behavior, scanning electron microscopy, and transmission electron microscopy characterization techniques. A perfect indicative response for this composite material was estimated by Fourier transform infrared spectra and X-ray diffraction as well. Both techniques displayed all intensive characteristic peaks regarding single-walled carbon nanotubes and poly(azomethine-ether) in the spectra or diffraction pattern for single-walled carbon nanotube/poly(azomethine-ether)1–5. The role of single-walled carbon nanotubes on the performance of poly(azomethine-ether) was considerably examined. Single-walled carbon nanotube/poly(azomethine-ether)1–5 showed relatively higher thermal stability. Single-walled carbon nanotube/poly(azomethine-ether)1 displayed the lowest final composite degradation temperature value (552°C), whereas single-walled carbon nanotube/poly(azomethine-ether)5 displayed the highest value (621°C). T10 and T25 values showed a gradual temperature increased while single-walled carbon nanotubes increased. Single-walled carbon nanotube/poly(azomethine-ether)1 showed the lowest thermal stability and single-walled carbon nanotube/poly(azomethine-ether)5 showed the highest thermal stability between all fabricated products. Furthermore, transmission electron microscopy images showed a prominent increase in single-walled carbon nanotubes diameters (40–60 nm). The conductivity values were significantly increased while single-walled carbon nanotubes content was increased and reached to the semiconductors. ε′ values were also increased in both single-walled carbon nanotube/poly(azomethine-ether)4,5 which have higher single-walled carbon nanotubes content.

The efficacy of electrospun polyurethane fibers with TiO2 in a real time weathering condition

This study focuses on the behavior of electrospun polyurethane fibers filled with nano, micro spheres and nanotube TiO2, thus nTiO2, mTiO2 or TiNT, under real time ultraviolet (UV) radiation. Analyses were conducted using scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis and differential scanning calorimetry (DSC) techniques. Significant changes of thermoplastic polyurethane (TPU) + 0.5% nTiO2 and TPU + 0.5% mTiO2 fibers morphology, that is, agglomerated TiO2 particles, were observed on material surfaces due to TPU fiber degradation, also supported by FTIR spectra given as reduction in the peaks intensities after UV radiation, especially in the case of TPU + 0.5% nTiO2. Further, after UV radiation, the initial degradation temperature reduction of the hard segment for all materials was up to 40℃. A significant reduction in the final degradation temperature (from 397.8℃ to 274.1℃) was noticed for the mTiO2 filled fibers, suggesting their photocatalytic activity, while Tg was increased up to 20℃ for almost all fillers added to TPU, thus indicating lower molecular chain mobility upon UV radiation.