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Polyethylene from renewable resources produced using sugarcane as raw material was modified with phosphonium ionic liquids. Tensile properties and thermal behavior of modified biopolyethylene in air and nitrogen atmosphere were studied. The thermal degradation of ionic liquids and their influence on thermal degradation of polyethylene from renewable resources were studied by thermogravimetric analysis (TGA). In general, modification of biopolyethylene with phosphonium ionic liquids resulted in improvement of tensile properties, i.e., tensile strength and Young's modulus. Thermal degradation of biopolyethylene modified with phosphonium ILs proceeds in one step in the range of 400–500 °C in nitrogen atmosphere. Modification of polyethylene with trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate ionic liquid resulted in increase in DTGpeaks and T10% temperatures toward higher temperature for modified polyethylene in comparison with unfilled PE sample both in air and nitrogen atmosphere. [ABSTRACT FROM AUTHOR]

Porous microspheres obtained from 2,3-epoxypropyl methacrylate (GMA) and 1,4-di(methacryloyloxymethyl) naphthalene (DMN) were modified by the reaction of active oxirane group with 1-(2-hydroxyethyl)-2-pyrrolidone (HP). Spherical shape of the copolymers was confirmed by scanning electron microscopy whereas low-temperature nitrogen adsorption–desorption method was applied to determine their porous structure. It was found that the modification process did not change noticeably the internal structure of the materials. The specific surface area for both types of materials ranged from 41 to 106 m2g−1 depending on the molar ratio of the monomers. Changes, however, were observed in reference to thermal properties. They were studied using differential scanning calorimetry and thermogravimetry coupled with FTIR in inert and oxidative conditions. The reaction with HP reinforced thermal stability of the modified microspheres in helium atmosphere. Their initial decomposition temperatures (IDTs) increased to 273–281 °C. In air atmosphere, the values of IDTs were at the same level (248–269 °C). The modified beads decomposed in three (helium) or two (air) stages. [ABSTRACT FROM AUTHOR]

The thermal features of potato, banana, corn and cassava starches were correlated with structural properties. These starches were characterized by SEM, XRD, FTIR-ATR, DSC and TG. The crystalline index of starches was evaluated, and the banana starch presented the highest. Infrared ratios of amorphous/crystalline regions were close to XRD data for potato and corn starches. The amylose ratio was correlated with Tg and gelatinization measurements by DSC, with some restrictions. TG experiments demonstrated that the crystalline array affects the thermal stability of starches, but the major component is the amylose ratio. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, silver nanoparticles were coated on different coir fibers to see their improvements in thermal behavior against the raw coir fiber. The fibers taken for the study are raw coir, parent coir (PC), modified coir-1 (MC1), modified coir-2 (MC2), silver nanoparticles (AgNPs)-coated PC and MC fibers. All the fibers were subjected to FESEM along with line scans of EDS, thermo gravimetry, differential thermal gravimetry and differential scanning calorimetry (DSC) analyses to observe the size of AgNPs and their responses to thermal behaviors, respectively. FESEM along with line scans of EDS shows the size of AgNPs varies from 40 to 210 nm in the coated fiber. The temperature of degradation (Tf (°C)) of AgNPs-coated coir increases significantly compared to PC and MCs. DTA and DSC analyses indicate higher thermal stability of silver-coated fibers over PC and MCs. In general, all the fibers show higher thermal stability over raw fiber and when coated fibers were compared, the thermal stabilities follow the order MC2 > MC1 > PC. It was also found that increase in the concentration of silver during coating further increases the thermal stability in all the cases without changing the order.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Hyperbranched poly(ester)s (HBPE) possess attributes for applications in a number of areas which include platforms for controlled release of actives and as rheology modifiers and coalescent agents in coatings. For the latter applications, properties such as the glass transition temperature and thermal stability are important. A number of HBPEs were produced with varying composition, molecular weight, degree of branching and end-group functionality in order to determine the effect of each on the HBPE thermal and rheological properties. These materials were synthesized from trimethylolpropane and the difunctional acids; adipic, phthalic and terephthalic. The chemical structure of the resulting HBPEs was fully characterized, particularly by SEC and NMR, and the thermal properties by DSC and TG. The glass transition temperature was found to depend primarily on HBPE composition and end-group functionality. The prominent feature of the thermal degradation for the hydroxyl-capped HBPE was dehydrative ether formation while that for carboxyl-capped polymers was decarboxylation. [ABSTRACT FROM AUTHOR]

This work is mainly focused on study of thermal and thermomechanical properties of obtained bio-based polyurethane (coded as bio-PU) composites via using different types of bio-components (bio-glycol, modified soybean oil and sisal fiber) in the procedure. The chemical structure, morphology and mechanical properties were also investigated and described in this manuscript in order to know more perfect characterization of produced composites. The bio-based polyurethane matrix of composites was synthesized via prepolymer method. Bio-PU composites were produced by dispersing 5 and 15 mass% of sisal fibers into the polyurethane matrix during their synthesis. To investigate the thermal stability of sisal fibers and bio-PU composites, the thermogravimetric method (TG) was used. Thermomechanical tests were performed by means of dynamic mechanical analysis (DMA). Based on the results of thermomechanical analysis, it was found that the sisal fibers amount has the impact on storage and loss modulus. Chemical structure was confirmed by FTIR spectra. Mechanical results and scanning microscopy images of the composites showed good interfacial adhesion between sisal fibers and the bio-based PU matrix. [ABSTRACT FROM AUTHOR]

This study focused on preparation and thermal properties of poly(stearyl methacrylate) shell (PSMA) microcapsules containing n-octadecane as a phase change material (PCM). Pentaerythritol triacrylate (PETA) and divinylbenzene (DVB) were employed as crosslinking agents. The surface morphologies, particle sizes, and distributions of the microencapsulated phase change material (microPCM) were studied by scanning electron microscopy. The thermal properties, thermal reliabilities, and thermal stabilities of the microPCMs were investigated by differential scanning calorimetry and thermal gravimetric analysis. The microPCM with DVB exhibits higher phase change enthalpies of melting (87.9 J g) and crystallization (94.8 J g) and a greater thermal stability in comparison with the microPCM with PETA. The phase change temperatures and enthalpies of the microPCMs varied little after thermal cycles. Thermal images showed that the gypsum board with PSMA/ n-octadecane microPCM possessed temperature-regulated property. Therefore, microencapsulated n-octadecane with PSMA as shell has good thermal energy storage and thermal regulation potential. [ABSTRACT FROM AUTHOR]

The viscoelastic characterization and thermal stability property of some multifunctional epoxy/anhydride systems cured at different schedules were investigated by dynamic mechanical thermal analysis (DMTA) in single cantilever mode at fixed frequency, and by non-isothermal thermogravimetric (TG) analysis, respectively. According to the DMTA results, three obviously different glass transition temperatures ( T), were observed, among which TGDDM/MHHPA system exhibits the largest T. While from the TG curves, the results of the mass loss and thermal stability showed that, after cured for a prolonged duration, the TGDDM/MHHPA system possessed the most excellent performance in heat resistance. [ABSTRACT FROM AUTHOR]

Pristine multiwalled carbon nanotubes (MWCNTs) were impregnated in acrylonitrile butadiene rubber (NBR) using internal dispersion kneader and two roller mixing mill to investigate the effects of various nanotubes concentrations on the thermal transport/stability of rubber nanocomposites. Thermal conductivity ( λ) and thermal impedance ( R) measurement experimental setups were established according to ASTM E1225-99 and D5470-03. The 1 mass % addition of MWCNTs in the polymer matrix has enhanced R up to 44 % and reduced λ of the rubber nanocomposite up to 40 % compare to the base composite formulation. Thermal decomposition and differential thermal analyses of the fabricated composite specimens simulate that the thermal stability and endothermic capability are augmented with increasing the nanotubes contents in the host matrix. The progressive incorporations of carbon nanotubes into the rubber matrix have efficiently influenced the composite specimens regarding glass transition, crystallization, and melting temperatures including their specific enthalpies. Scanning electron microscopy along with the energy dispersive spectroscopy was used to analyze MWCNTs dispersion in NBR matrix, compositional analysis of the nanocomposite, and impregnated nanotubes. [ABSTRACT FROM AUTHOR]

It has been shown that introducing carbon nanotubes (CNT) into a polymer matrix has a beneficial effect on thermal stability of composites. While the specific effects noted differ depending on many parameters, the general trend is an increase in the degradation temperature and reduction in the degradation rate, quantified as the mass decline over time. The purpose of this study is to evaluate how CNTs influence the main degradation process of composites made with polystyrene containing 2, 3 and 5 % of CNTs. Thermogravimetric experiments are performed, with nitrogen purge, at multiple linear heating ramps. The effects of the nanotubes on the degradation of polystyrene are evaluated. Insightful kinetic parameters were obtained for the main process making use of a recently developed model, which is adapted to the thermogravimetric context. The model allows the means to separate the main process from other processes, which could interfere with the kinetic analysis, and also subtract the residual mass, which could produce an apparent stabilizing effect. The main degradation process is clearly stabilized by the presence of nanotubes, although the stabilization is more pronounced at the lowest of the filler contents considered. Clear effects of nanotubes on kinetic parameters were observed. [ABSTRACT FROM AUTHOR]

The influence of the structure properties relationships of silicone incorporated polyimide (PI) on thermal stability was investigated by using single scan thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) in nitrogen. Four systems have been synthesized based on monomer 4-(4-(1-(4-(4-aminophenoxy) phenyl)-1-methylethyl) phenoxy) aniline (BAPP)/3,3′,4,4′-Biphenyltetracarboxylic dianhydride including parent PI (S-1), PI siloxane copolymer (S-2 and S-3), and PI siloxane hybrid (S-4). The derivative thermogravimetric analysis (DTG) and DSC curves indicate a double and single stage decomposition process and glass transition temperature ( T), respectively. While the PI, PIS, and PSH showed distinctive features towards thermal analysis, it was found that the rate of degradation (δα/δ t) was influenced by the flexibility of Si-O-Si in the backbone and in Si-O-Si itself. These results revealed that the presence of Si-O-Si in either the backbone or matrix indicates its stability with regard to high thermal service applications. [ABSTRACT FROM AUTHOR]

A series of silicon containing poly(ester imide)s [PEIs] were synthesized using novel vinyl silane diester anhydride (VSEA) and various aromatic and aliphatic dimines by two-step process includes ring-opening polyaddition reaction to form poly(amic acid) and thermal cyclo-dehydration process to obtain poly(ester imide)s. VSEA was synthesized by using dichloro methylvinylsilane and trimellitic anhydride in the presence of K2CO3 by nucleophilic substitution reaction. The PEIs were characterized by FTIR spectroscopy. The thermal properties of PEIs were investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) methods. The prepared PEIs showed glass transition temperatures in the range of 320–350°C and their 5% mass loss was recorded in the temperature range of 500–520°C in nitrogen atmosphere. These had char yield in the range of 45–55% at 800°C. [ABSTRACT FROM AUTHOR]

Thermal properties of control phenol formaldehyde (cpf) adhesive and lignin substituted phenol formaldehyde (lpf) adhesives have been investigated in detail. The effect of varying lignin mass percent of phenol and source of lignin like bagasse, eucalyptus bark, coconut coirpith and coffee bean shell on the thermal stability have been studied using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). 50 mass% of lignin loading in cpf adhesive shows better bond strength, whereas lignin incorporation up to 25 mass% yields a resin of thermal stability comparable to cpf. Loading of lignin in cpf delays the first thermal transition event. The mass loss in this event was found to increase with increasing lignin content. Lignin source has significant effect on the thermal stability of lpf resins. Rate of curing is enhanced by incorporation of lignin into cpf. [ABSTRACT FROM AUTHOR]

Thermal analysis of fusion and decomposition processes were carried out on recently synthetized pharmaceutical compounds in order to establish thermal stability criteria. This study was carried out using thermogravimetry, TG, and differential scanning calorimetry, DSC. Degradation and fusion temperatures have been produced as thermal data with the aim of to study the thermal stability of the compounds. Relationship is found among stability and a series of effects of structure of the compounds. The compounds which present an amide functional group in the central molecule are more stable because they have a comparatively higher fusion and degradation temperature. In addition, the stability of this type of compounds depends on the position of the electrophilic substitution (in ortho, meta or para). Likewise, the groups linked to the aromatic ring with high electronic density give stability, and therefore are able to delocalize the charge in a greater spacial interval. Therefore, criteria for the selection of substituents have established that improve the stability of compounds [ABSTRACT FROM AUTHOR]

The present paper discusses the results of assessing thermal properties of nitrile rubber, Perbunan NT 3945 and its peroxide vulcanizates, before and after their swelling in solvents such as benzene, toluene and dimethylformamide. The measurements were carried out by means of differential scanning calorimetry (DSC) and thermogravimetry (TG) under nitrogen. It has been found that a slight rise in the glass transition temperature due to the elastomer cross-linking is clearly revealed under the influence of its vulcanizates swelling in solvents whose solubility parameters considerably differ from the solubility parameters of the polymer. The thermal curves of swollen samples reveal processes resulting from polymer-solvent interactions and thermodesolvation processes, which accompany the initial stage of solvent evaporation. [ABSTRACT FROM AUTHOR]

The paper presents the thermal properties of fibres made of a modified polyimideamide. The effects of as-spun draw ratio and deformation during the fibre drawing stage on the structure, thermal properties, moisture absorption and tenacity of the obtained fibres have been determined. Based on the findings obtained by the DTA and DSC methods, it has been found that the modification of the polymer under investigation causes its glass transition temperature to decrease through the increase of molecular mobility. At the same time, the heat-resistant fibres with the amorphous oriented structure are characterized by a tenacity of 16 cN/tex, good absorption properties and increased porosity. The thermal stability indices of the examined fibres have been determined on the basis of thermogravimetric curves obtained both under air and inert gas. [ABSTRACT FROM AUTHOR]