scholarly journals Heterogenized Imidazolium-Based Ionic Liquids in Pebax®Rnew. Thermal, Gas Transport and Antimicrobial Properties

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1419
Author(s):  
Gabriele Clarizia ◽  
Paola Bernardo ◽  
Sabrina C. Carroccio ◽  
Martina Ussia ◽  
Cristina Restuccia ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Antimicrobial Activity ◽  
Ionic Liquids ◽  
Gas Transport ◽  
Gas Permeability ◽  
Bacterial Strains ◽  
Scanning Calorimetry ◽  
Neat Polymer ◽  
Practical Applications ◽  
Good Thermal Stability

Imidazolium-based ionic liquids (ILs) have interesting antimicrobial activity and their inclusion in a flexible film is ideal to take advantage of their properties in practical applications. Poly(ether-block-amide) (Pebax®Rnew) films were prepared by solution casting, loading two synthetized ILs (1-hexadecyl-3-methylimidazolium dimethyl-5-sulfoisophthalate [Hdmim][DMSIP], IL1 and 1-octyloximethyl-3-methylimidazolium hexafluorophosphate [OOMmim][PF6], IL2) up to 5 wt.%. The ILs were characterized by 1H NMR and MALDI-TOF spectroscopy. The films were investigated for miscibility, morphology, wettability, spectral properties and gas transport. The films display a good thermal stability (>200 °C). Differential scanning calorimetry (DSC) proves phase separation in the blends, that is consistent with FTIR analysis and with the island-like surface morphology observed in the micrographs. Gas permeability tests revealed that the IL-loaded films are dense and poreless, keeping the selectivity of the polymer matrix with a somewhat lessened permeability owing to the impermeable ILs crystals. The film antimicrobial activity, evaluated against Gram-negative and Gram-positive bacterial strains, was correlated to the structure of the incorporated ILs. The smaller IL2 salt did not modify the hydrophobic nature of the neat polymer and was readily released from the films. Instead, IL1, having a longer alkyl chain in the cation, provided a promising antimicrobial activity with a good combination of hydrophilicity, permeability and thermal stability.

High partial thermal conductivity of luminescence sites: a crucial factor for reducing the heat-induced lowering of the luminescence efficiency

2021 ◽  
Author(s):  
Ni Luo ◽  
Jing Xu ◽  
Xiyue Cheng ◽  
ZhenHua Li ◽  
Yidong Huang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Practical Applications ◽  
Good Thermal Stability ◽  
The Past ◽  
Luminescence Efficiency ◽  
Thermal Stability Of

The good thermal stability of a phosphor is crucial for its practical applications. Unfortunately, in the past decades, only Gurney-Mott equation was available to describe the relation between the luminescence...

scholarly journals Electrospun Silk-Boron Nitride Nanofibers with Tunable Structure and Properties

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1093
Author(s):  
Ye Xue ◽  
Xiao Hu
Keyword(s):  
Thermal Stability ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Environmental Research ◽  
Strong Interactions ◽  
Helical Structures ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Good Thermal Stability ◽  
Thermal Stability Of

In this study, hexagonal boron nitride (h-BN) nanosheets and Bombyx mori silk fibroin (SF) proteins were combined and electrospun into BNSF nanofibers with different ratios. It was found that the surface morphology and crosslinking density of the nanofibers can be tuned through the mixing ratios. Fourier transform infrared spectroscopy study showed that pure SF electrospun fibers were dominated by random coils and they gradually became α-helical structures with increasing h-BN nanosheet content, which indicates that the structure of the nanofiber material is tunable. Thermal stability of electrospun BNSF nanofibers were largely improved by the good thermal stability of BN, and the strong interactions between BN and SF molecules were revealed by temperature modulated differential scanning calorimetry (TMDSC). With the addition of BN, the boundary water content also decreased, which may be due to the high hydrophobicity of BN. These results indicate that silk-based BN composite nanofibers can be potentially used in biomedical fields or green environmental research.

scholarly journals Thermal characterization of novel aliphatic polyesters with ether and thioether linkages

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Soccio ◽  
N. Lotti ◽  
L. Finelli ◽  
A. Munari
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Chemical Structure ◽  
Room Temperature ◽  
Crystallization Rate ◽  
Thermal Characterization ◽  
Scanning Calorimetry ◽  
Aliphatic Polyesters ◽  
Good Thermal Stability

AbstractSeveral novel ether or thioether linkage containing aliphatic polyesters and poly(alkylene dicarboxylate)s were synthesized for comparison and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by thermogravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability, even though lower for the ether or thioether linkage-containing polyesters. The decrement of the thermal stability appears to be more relevant in the case of the presence of sulphur atoms. At room temperature the samples appeared semicrystalline, except PTTDG and PDEDG, which were viscous oils; the effect of the introduction of ether or thioether group was an increment of the Tgvalue, a decrement of the melting temperature and a significant decrease of the crystallization rate. The entity of the variations was found to be affected by the kind of group introduced, and the trend observed can be explained on the basis of atom electronegativity and dimensions

Heat-resistant and photoluminescent indole-based poly(ether sulfone)s

2017 ◽  
Vol 30 (4) ◽  
pp. 475-479 ◽  
Author(s):  
Wenxuan Wei ◽  
Li Yang ◽  
Guanjun Chang
Keyword(s):  
Thermal Stability ◽  
High Performance ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Condensation Polymerization ◽  
High Glass Transition Temperature ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
High Performance Polymers ◽  
Good Agreement

Indole-based poly(ether sulfone)s (PINESs), as novel high-performance polymers, have been obtained by the condensation polymerization of 4-hydroxyindole and hydroquinone with activated difluoro monomers via a catalyst-free nucleophilic substitution reaction. The structures of the polymers are characterized by means of Fourier transform infrared and proton nuclear magnetic resonance spectroscopy, and the results show good agreement with the proposed structures. Differential scanning calorimetry and thermogravimetric analysis measurements exhibit that polymers possess high glass transition temperature ( Tgs > 245°C) and good thermal stability with high decomposition temperatures ( Tds > 440°C). In addition, due to their special structure, PINESs are endowed with significantly strong photonic luminescence in N, N-dimethylformamide.

Novel polyimides based on diamine containing thiazole units with thioether linkage and pyridine as pendent group

2017 ◽  
Vol 30 (7) ◽  
pp. 840-846 ◽  
Author(s):  
Jafar Rezania ◽  
Abbas Shockravi ◽  
Morteza Ehsani ◽  
Vahid Vatanpour
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Pyridine Ring ◽  
Polar Solvent ◽  
Nitrogen Atmosphere ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Good Thermal Stability ◽  
Pendent Group ◽  
High Yields

Three new organic-soluble polyimides (PIs) bearing flexible thioether linkages, thiazole, and pyridine ring units were synthesized from a novel thioether-bridged diamine monomer and commercially available aromatic dianhydrides (1–3) via chemical imidization method. The resulting polymers were obtained in high yields and possessed inherent viscosities in the range of 0.67–0.89. The PIs are characterized by Fourier-transform infrared (FTIR), nuclear magnetic resonance (NMR), differential scanning calorimetry, and thermogravimetric analysis (TGA). All of the PIs exhibited excellent solubility in polar solvent. The polymers showed good thermal stability with glass transition temperatures ( Tgs) in the range of 194–244°C, and decomposition temperatures ( T5%) exceeding 300°C were observed using TGA in nitrogen atmosphere for the current polymers.

Thermal properties of a series of tetrafunctional fluorene-based oxazines/P-a blends

2016 ◽  
Vol 29 (10) ◽  
pp. 1139-1147 ◽  
Author(s):  
Zi Sang ◽  
Tiantian Feng ◽  
Wenbin Liu ◽  
Jun Wang ◽  
Mehdi Derradji
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Mechanical Analysis ◽  
Proton Nuclear Magnetic Resonance ◽  
Primary Amines ◽  
Resonance Spectroscopy ◽  
High Glass Transition Temperature ◽  
Scanning Calorimetry ◽  
Good Thermal Stability

A new series of aniline and aniline-mixed tetrafunctional fluorene-based oxazine monomers were synthesized using 2,7-hydroxy-9,9-bis-(4-hydroxyphenyl) fluorene, paraformaldehyde, and primary amines (including aniline or aniline mixed with n-butylamine or n-octylamine composition). Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy were used to characterize the structure of the monomers. The copolymers were obtained by adding the monomers into a typical monofunctional polybenzoxazine (phenol-aniline-based benzoxazine). Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis were performed to study the thermal properties of the copolymers. The copolymers exhibited high glass transition temperature values (164–201°C). A good thermal stability was also obtained with a 5% weight loss temperature over 355°C and high char yields at 800°C (42–50%).

Synthesis and Thermal Stability of Unsaturated Polyamides

1992 ◽  
Vol 4 (2) ◽  
pp. 67-71
Author(s):  
N. R. Patel ◽  
N. Z. Patel ◽  
R. M. Patel
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Scanning Calorimetry ◽  
Aromatic Diamines ◽  
Good Thermal Stability ◽  
Kinetics Of Decomposition ◽  
Glutaconic Acid ◽  
Kinetics Of ◽  
Thermal Stability Of

Unsaturated polyamides were prepared by condensing /3(4-ethoxyphenyl) glutaconic acid with various aromatic diamines. The polycondensates were characterized by IR spectroscopy, vapor phase osmometry, thermogravimetric analysis, differential scanning calorimetry and elemental analysis. All resins were found to decompose in the range '-210-600 °C. The kinetics of decomposition were studied. The results indicated that the resins possess reasonably good thermal stability.

scholarly journals Gas Transport Phenomena and Polymer Dynamics in PHB/PLA Blend Films as Potential Packaging Materials

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 647 ◽  
Author(s):  
Valentina Siracusa ◽  
Svetlana Karpova ◽  
Anatoliy Olkhov ◽  
Anna Zhulkina ◽  
Regina Kosenko ◽  
...  
Keyword(s):  
High Performance ◽  
Gas Transport ◽  
Gas Permeability ◽  
Point Of View ◽  
Segmental Mobility ◽  
Scanning Calorimetry ◽  
Blend Films ◽  
Spin Resonance ◽  
Temperature Dependences

Actually, in order to replace traditional fossil-based polymers, many efforts are devoted to the design and development of new and high-performance bioplastics materials. Poly(hydroxy alkanoates) (PHAS) as well as polylactides are the main candidates as naturally derived polymers. The intention of the present study is to manufacture fully bio-based blends based on two polyesters: poly (3-hydroxybutyrate) (PHB) and polylactic acid (PLA) as real competitors that could be used to replace petrol polymers in packaging industry. Blends in the shape of films have been prepared by chloroform solvent cast solution methodology, at different PHB/PLA ratios: 1/0, 1/9, 3/7, 5/5, 0/1. A series of dynamic explorations have been performed in order to characterize them from a different point of view. Gas permeability to N2, O2, and CO2 gases and probe (TEMPO) electron spin resonance (ESR) analyses were performed. Blend surface morphology has been evaluated by Scanning Electron Microscopy (SEM) while their thermal behavior was analyzed by Differential Scanning Calorimetry (DSC) technique. Special attention was devoted to color and transparency estimation. Both probe rotation mobility and N2, O2, and CO2 permeation have monotonically decreased during the transition from PLA to PHB, for all contents of bio-blends, namely because of transferring from PLA with lower crystallinity to PHB with a higher one. Consequently, the role of the crystallinity was elucidated. The temperature dependences for CO2 permeability and diffusivity as well as for probe correlation time allowed the authors to evaluate the activation energy of both processes. The values of gas transport energy activation and TEMPO rotation mobility are substantially close to each other, which should testify that polymer segmental mobility determines the gas permeability modality.

scholarly journals Thermal Stability Analysis of the Mg/TeO2 Ignition Composition after 180 °C Exposure

2020 ◽  
Vol 10 (22) ◽  
pp. 8122
Author(s):  
Xiang He ◽  
Yaokun Ye ◽  
Nan Yan ◽  
Feng Ding ◽  
Chaozhen Li ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Environment ◽  
Exothermic Reaction ◽  
Pressure Rise ◽  
Optical Microscope ◽  
Main Reaction ◽  
Scanning Calorimetry ◽  
Change Analysis ◽  
Good Thermal Stability ◽  
Thermal Stability Of

In order to satisfy the performance requirements of the pyrotechnic ignition composition of a space mission under an extreme thermal environment, it is necessary to analyze and verify the thermal stability of magnesium/tellurium dioxide (Mg/TeO2) ignition composition at a temperature of 180 °C. The thermal stability of the ignition composition of Mg/TeO2 and its components after exposure to 180 °C for 2–10 days was studied by means of apparent morphology analysis, differential scanning calorimetry (DSC), X-ray diffraction (XRD), content change analysis, and the P-t curve test. The results showed that after exposure to 180 °C for 2–10 days, no obvious changes, such as ruptures, expansion, or shrinkage, were found by optical microscope, and no changes in morphology and surface details were found by scanning electron microscope (SEM). XRD showed that no other new substance was found in the mixture except magnesium hydroxide (Mg (OH)2). DSC showed that the main reaction peak temperature of the ignition composition of Mg/TeO2 was after 500 °C and that no endothermic/exothermic reaction occurred before 380 °C. The exothermic pre-reaction took place at 381 °C to 470 °C, the weight loss ratio was within 0.71%, the content of the magnesium component varied from 0.49% to 0.90%, the peak pressure attenuation of the ignition composition of 360-mesh Mg/TeO2 was 8.07%, and the pressure rise time was basically unchanged. The results showed that the ignition composition of Mg/TeO2 had good thermal stability after exposure to 180 °C temperatures.

Extraction of Collagen from Catfish (Clarias gariepnus) Waste and Determination of its Physico-chemical Properties

2012 ◽  
Vol 9 (1) ◽  
pp. 29
Author(s):  
Normah Ismail ◽  
Nurul Asyiraf Abdul Jabar
Keyword(s):  
Thermal Stability ◽  
Food Industry ◽  
Chemical Properties ◽  
White Crystal ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
Physico Chemical ◽  
Pale Colour ◽  
Increasing Temperature

Collagen was extracted from catfish (Clarias gariepnus) waste using 0.5M acetic acid and its subsequent precipitation in 2.6M NaCl. The resultant collagen was analysed with respect to its moisture content and physico­chemical properties including yield, pH, protein content, colour, odour and thermal stability. A yield of 16. 4% and positive collagen attributes indicate that catfish waste has potential as a collagen source. The snowy white, crystal-like and light textured collagen comprises of 5.97% protein and 0.46% moisture, and exhibits a pH of 4.75. Sensory evaluation indicates that the collagen has a slight fishy odour. Viscosity analysis indicates a steady decrease with increasing temperature over the range considered (20-50°C). The pale colour exhibited and limited odour emitted by the extracted collagen indicate that catfish waste collagen could be applied in the food industry without resulting in any undesirable food products attributes. Differential Scanning Calorimetry (DSC) analysis indicated that the collagen exhibits good thermal stability and denatures at a high temperature in a similar manner to mammalian collagen.

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