Sequence Effects on Properties of the Poly(p-phenylene terephthalamide)-based Macroinitiators and their Comb-like Copolymers Grafted by Polystyrene Side Chains

2014 ◽  
Vol 67 (1) ◽  
pp. 39 ◽  
Author(s):  
Shuming Du ◽  
Jie Zhang ◽  
Yan Guan ◽  
Xinhua Wan
Keyword(s):  
Thermal Stability ◽  
Graft Copolymers ◽  
Side Chains ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Terephthaloyl Chloride ◽  
Discernible Effect ◽  
Sequence Effects ◽  
Concentrated Sulfuric Acid

Two poly(p-phenylene terephthalamide) (PPTA)-based macroinitiators with random and alternate sequences, i.e. poly(p-phenylene terephthalamide)-ran-poly[p-phenylene (2,2,6,6-tetramethylpiperidinyl-1-oxy)terephthalamide)] (CPPTA-ran) and poly(p-phenylene terephthalamide)-alt-poly[p-phenylene (2,2,6,6-tetramethylpiperidinyl-1-oxy)terephthalamide)] (CPPTA-alt), were prepared via copolycondensation of terephthaloyl chloride, 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)-functionalized terephthaloyl chloride, and p-phenylenediamine. The graft copolymers consisting of rigid PPTA backbones and polystyrene side chains were obtained by nitroxide-mediated radical polymerization. Both macroinitiators and graft copolymers were characterized by thermal gravimetric analysis, differential scanning calorimetry, wide-angle X-ray diffraction, and polarized optical microscopy. The regular incorporation of the TEMPO-containing co-unit gives rise to remarkable effects on the thermal stability, lyotropic liquid crystallinity, and macromolecular packing in bulk. CPPTA-alt shows better thermal stability and more ordered intermolecular structure than CPPTA-ran. The former generates a nematic phase at a concentration of 18 wt-% in concentrated sulfuric acid, whereas the latter does so at a concentration of 12 wt-%. For the graft copolymers, the alternative main chains exhibit sharper diffraction than the random ones. However, the sequence change exerts no discernible effect on other properties.

Thermal Stability and Crystallization Behavior of PP/Organoclay Phase Change Composites

2013 ◽  
Vol 785-786 ◽  
pp. 123-126
Author(s):  
Ying Ye ◽  
Kun Yan Wang ◽  
Ge Chang ◽  
Qian Ying Jiang
Keyword(s):  
Thermal Stability ◽  
Phase Change ◽  
Crystallization Behavior ◽  
Melt Blending ◽  
X Ray Diffraction ◽  
Nucleation Agent ◽  
Scanning Calorimetry ◽  
Blending Method ◽  
Phase Change Composites ◽  
Change Material

Polypropylene/organoclay modified by dodecanol phase change material were prepared by melt blending method. The thermal stability and crystallization behavior was studied by thermogravimetry (TG), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). TG results indicated the window of processing of PP could be improved by adding small amount organoclay modified by dodecanol to the blend. DSC showed the organoclay modified by dodecanol affected the crystallization behavior of PP as heterogeneous nucleation agent. XRD results show that the organoclay modified by dodecanol does not change the crystal structure in the blends but only decrease the intensity of the diffraction peak.

scholarly journals A Facile Method to Construct MXene/CuO Nanocomposite with Enhanced Catalytic Activity of CuO on Thermal Decomposition of Ammonium Perchlorate

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2457 ◽  
Author(s):  
Haifeng Zhao ◽  
Jing Lv ◽  
Junshan Sang ◽  
Li Zhu ◽  
Peng Zheng ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Catalytic Activity ◽  
Ammonium Perchlorate ◽  
Photoelectron Spectra ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Improved Performance ◽  
Calcination Method

In this work, a mixing-calcination method was developed to facilely construct MXene/CuO nanocomposite. CuO and MXene were first dispersed in ethanol with sufficient mixing. After solvent evaporation, the dried mixture was calcinated under argon to produce a MXene/CuO nanocomposite. As characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and X-ray photoelectron spectra (XPS), CuO nanoparticles (60–100 nm) were uniformly distributed on the surface and edge of MXene nanosheets. Furthermore, as evaluated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), the high-temperature decomposition (HTD) temperature decrease of ammonium perchlorate (AP) upon addition of 1 wt% CuO (hybridized with 1 wt% MXene) was comparable with that of 2 wt% CuO alone, suggesting an enhanced catalytic activity of CuO on thermal decomposition of AP upon hybridization with MXene nanosheets. This strategy could be further applied to construct other MXene/transition metal oxide (MXene/TMO) composites with improved performance for various applications.

scholarly journals Thermal behaviour study of solid state compounds of manganese (II), zinc (II) and lead (II) with cinnamic acid

1998 ◽  
Vol 23 (0) ◽  
pp. 09-16
Author(s):  
Marco Aurélio da Silva CARVALHO FILHO ◽  
Massao IONASHIRO
Keyword(s):  
Thermal Stability ◽  
Aqueous Solution ◽  
Differential Scanning Calorimetry ◽  
Cinnamic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Manganese Zinc ◽  
Behaviour Study ◽  
Derivative Thermogravimetry

Compounds of cinnamic acid with manganese, zinc and lead have been prepared in aqueous solution. Thermogravimetry, derivative thermogravimetry (TG, DTG), differential scanning calorimetry (DSC), X-ray diffraction and complexometry have been used in the characterization as well as in the study of the thermal stability and interpretation concerning the thermal decomposition.

scholarly journals Development and In-Vitro Evaluation of pH Responsive Polymeric Nano Hydrogel Carrier System for Gastro-Protective Delivery of Naproxen Sodium

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Rai Muhammad Sarfraz ◽  
Muhammad Rouf Akram ◽  
Muhammad Rizwan Ali ◽  
Asif Mahmood ◽  
Muhammad Usman Khan ◽  
...  
Keyword(s):  
Drug Release ◽  
Naproxen Sodium ◽  
Research Work ◽  
Entrapment Efficiency ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Swelling Behaviour ◽  
X Ray

Current research work was carried out for gastro-protective delivery of naproxen sodium. Polyethylene glycol-g-poly (methacrylic acid) nanogels was developed through free radical polymerization technique. Formulation was characterized for swelling behaviour, entrapment efficiency, Fourier transform infrared (FTIR) spectroscopy, Differential scanning calorimetry (DSC), and Thermal Gravimetric Analysis (TGA), Powder X-ray diffraction (PXRD), Zeta size distribution, and Zeta potential measurements, and in-vitro drug release. pH dependent swelling was observed with maximum drug release at higher pH. PXRD studies confirmed the conversion of loaded drug from crystalline to amorphous form while Zeta size measurement showed size reduction. On the basis of these results it was concluded that prepared nanogels proved an effective tool for gastro-protective delivery of naproxen sodium.

The Influence of Calcination Temperature on Quantitative Phase of Hematite from Iron Stone Tanah Laut

2015 ◽  
Vol 1112 ◽  
pp. 489-492
Author(s):  
Ali Mufid ◽  
M. Zainuri
Keyword(s):  
Particle Size ◽  
Calcination Temperature ◽  
Thermo Gravimetric Analysis ◽  
Precipitation Method ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Particle Size Analyzer ◽  
Co Precipitation

This research aims to form particles of hematite (α-Fe2O3) with a basis of mineral iron ore Fe3O4 from Tanah Laut. Magnetite Fe3O4 was synthesized using co-precipitation method. Further characterization using X-ray fluorescence (XRF) to obtain the percentage of the elements, obtained an iron content of 98.51%. Then characterized using thermo-gravimetric analysis and differential scanning calorimetry (TGA-DSC) to determine the calcination temperature, that at a temperature of 445 °C mass decreased by 0.369% due to increase in temperature. Further Characterization of X-ray diffraction (XRD) to determine the phases formed at the calcination temperature variation of 400 °C, 445 °C, 500 °C and 600 °C with a holding time of 5 hours to form a single phase α-Fe2O3 hematite. Testing with a particle size analyzer (PSA) to determine the particle size distribution, where test results indicate that the α-Fe2O3 phase of each having a particle size of 269.7 nm, 332.2 nm, 357.9 nm, 412.2 nm. The best quantity is shown at a temperature of 500 °C to form the hematite phase. This result is used as the calcination procedure to obtain a source of Fe ions in the manufacture of Lithium Ferro Phosphate.

scholarly journals Effect of Sr2TiMnO6 fillers on mechanical, dielectric and thermal behaviour of PMMA polymer

2015 ◽  
Vol 05 (03) ◽  
pp. 1550018 ◽  
Author(s):  
P. Thomas ◽  
B. S. Dakshayini ◽  
H. S. Kushwaha ◽  
Rahul Vaish
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Thermo Gravimetric Analysis ◽  
Mechanical Analysis ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Transition Formula ◽  
Thermal Stability Of ◽  
Pmma Polymer

Composites of poly(methyl methacrylate) (PMMA) and [Formula: see text] (STMO) were fabricated via melt mixing followed by hot pressing technique. These were characterized using X-ray diffraction (XRD), thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), thermo mechanical analysis (TMA) and impedance analyser for their structural, thermal and dielectric properties. The coefficient of thermal expansion (CTE) was measured between 40°C and 100°C for pure PMMA is 115.2 ppm/°C, which was decreased to 78.58 ppm/°C when the STMO content was increased to 50 wt.% in PMMA. There was no difference in the glass transition ([Formula: see text]) temperature of the PMMA polymer and their composites. However, the FTIR analysis indicated possible interaction between the PMMA and STMO. The density and the hardness were increased as the STMO content increased in the PMMA matrix. Permittivity was found to be as high as 30.9 at 100 Hz for the PMMA+STMO-50 wt.% composites, indicating the possibility of using these materials for capacitor applications. The thermal stability of polymer was enhanced by incorporation of STMO fillers.

Synthesis and thermal stability studies of polyaniline/silver nanocomposite based on reduction of silver ions using polyaniline

2011 ◽  
Vol 23 (7) ◽  
pp. 513-517 ◽  
Author(s):  
Mohsen Ghorbani ◽  
Mohammad Soleimani Lashkenari ◽  
Hossein Eisazadeh
Keyword(s):  
Thermal Stability ◽  
Chemical Structure ◽  
Aqueous Media ◽  
Silver Ions ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Stability Studies ◽  
Scanning Calorimetry ◽  
Chemical Polymerization ◽  
Silver Nanocomposite

This study investigated the preparation and properties of polyaniline/silver (PAn/Ag2O) nanocomposite in aqueous media by chemical polymerization of aniline in the presence of ammonium peroxydisulphate as an oxidant. The products were investigated in terms of morphology, chemical structure, thermal stability and thermal degradation using scanning electron microscopy, Fourier transform infrared, thermal gravimetric analysis and differential scanning calorimetry, respectively. The results indicated that the properties of products were dependent on the nanocomposite structure.

Study of the structure and thermal characteristics of nanocomposites based on polyvinyl alcohol and intercalated montmorillonite

2019 ◽  
pp. 089270571987919
Author(s):  
Volodymyr Krasinskyi ◽  
Ivan Gajdos ◽  
Oleh Suberlyak ◽  
Viktoria Antoniuk ◽  
Tomasz Jachowicz
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Acrylic Acid ◽  
Polyvinyl Alcohol ◽  
Thermal Characteristics ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
The Degree Of Crystallinity

The structure and thermal characteristics of nanocomposites based on polyvinyl alcohol (PVA) and montmorillonite (MMT) intercalated with polyvinylpyrrolidone were investigated by X-ray diffraction analysis and differential scanning calorimetry. The modification of PVA with intercalated MMT reduces the degree of crystallinity of the resulting nanocomposites but significantly increases their thermal stability. Under ultrasound, the intercalated MMT was completely distributed in a PVA solution and formed a monocrystalline structure. Films based on PVA with modified MMT were cross-linked at 110°C in the presence of 5 wt% acrylic acid and 0.5 wt% Ferrous(II) sulfate as an initiator. The formed films have a homogeneous cross-linked structure.

scholarly journals Lipase mediated synthesis of polycaprolactone and its silica nanohybrid

2019 ◽  
Vol 91 (6) ◽  
pp. 957-965
Author(s):  
Meltem Akkulak ◽  
Yasemin Kaptan ◽  
Yasar Andelib Aydin ◽  
Yuksel Avcibasi Guvenilir
Keyword(s):  
Average Molecular Weight ◽  
Proton Nuclear Magnetic Resonance ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structural Investigations ◽  
Crystallinity Degree ◽  
Molecular Weights ◽  
H Nmr

Abstract In this study, rice husk ash (RHA) silanized with 3-glycidyloxypropyl trimethoxysilane was used as support material to immobilize Candida antarctica lipase B. The developed biocatalyst was then utilized in the ring opening polymerization (ROP) of ε-caprolactone and in situ development of PCL/Silica nanohybrid. The silanization degree of RHA was determined as 4 % (w) by thermal gravimetric analysis (TGA). Structural investigations and calculation of molecular weights of nanohybrids were realized by proton nuclear magnetic resonance (1H NMR). Crystallinity was determined by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Scanning Electron Microscopy (SEM) was used for morphological observations. Accordingly, the PCL composition in the nanohybrid was determined as 4 %, approximately. Short chained amorphous PCL was synthesized with a number average molecular weight of 4400 g/mol and crystallinity degree of 23 %. In regards to these properties, synthesized PCL/RHA composite can find use biomedical applications.

Ultrasonic Degradation Performance of the CeZrMo Heteropoly Salt with Keggin Structure

2012 ◽  
Vol 518-523 ◽  
pp. 2965-2968
Author(s):  
Zhi Hong Zhang ◽  
Feng Xue
Keyword(s):  
Thermal Stability ◽  
Degradation Rate ◽  
Keggin Structure ◽  
Molecular Formula ◽  
Ultrasonic Frequency ◽  
Gravimetric Analysis ◽  
Ultrasonic Power ◽  
X Ray Diffraction ◽  
Crystal Water ◽  
Good Thermal Stability

A new heteropoly salt with Keggin structure of the 1:1:11 series had been synthesized, and characterized the structure by the foruier transform infrared spectroscopy (IR), ultraviolet spectra (UV) and X-ray diffraction (XRD).The thermal stability and the number of the crystal water was analyzed by the thermal gravimetric analysis/differential thermal analysis (TG/DTA). It was showed the molecular formula was Na5[Ce(ZrMo11O39)]•16H2O( Abbrev.CeZrMo),it possessed Keggin structure and had good thermal stability. The influences on the degradation rate, such as the amount of the CeZrMo, the initial concentration of the AGB dye wastewater, the ultrasonic frequency and power, were investigated. The results showed that the degradation rate could reach 88.01% after 60min irradiation, when the amount of the CeZrMo was 0.8g•L-1, the concentration of the AGB was 10mg•L-1, the ultrasonic frequency was 45kHz and the ultrasonic power was 100W.

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