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Thermal properties and the decomposition path of more environmentally friendly polymers in both atmospheres: inert and oxidizing have been studied with a use of simultaneous TG/FTIR/QMS and DSC methods. The polymeric materials in the UV-polymerization process of cyclohexyl methacrylate and methacrylate monomer obtained from natural terpene alcohol: citronellol, using different compositions of monomers were prepared. The glass transition temperature (Tg) and thermal stability of these high solvent and chemical resistant materials were dependent on the composition and increased with increasing cyclic monomer content in the compositions. The Tg changed from 9.8˚C to 47.5˚C and a thermal stability from 195˚C to 222˚C (inert atmosphere) and from 160˚C to 217˚C (oxidizing atmosphere). The TG/FTIR/QMS analysis proved the emission of cyclohexyl methacrylate, citronellyl methacrylate and their lower molecular mass decomposition fragments, e.g., propene, cyclohexane, citronellol, citronellal, formic acid, methacrylic acid and CO, CO2 during heating of these materials in helium and air atmospheres. It indicated the same radical mechanism of their decomposition in both atmospheres which meant that the presence of oxygen did not affect the course of decomposition but reduced the initial decomposition temperature of the copolymers. [ABSTRACT FROM AUTHOR]

We have developed an analytical method to quantitatively analyze differential scanning calorimetry (DSC) experimental data. This method provides accurate determination of thermal properties such as equilibrium melting temperature, latent heat, change of heat capacity which can be performed automatically without intervention of a DSC operator. DSC is one of the best techniques to determine the thermal properties of materials. However, the accuracy of the transition temperature and enthalpy change can be affected by artifacts caused by the instrumentation, sampling, and the DSC analysis methods which are based on graphical constructions. In the present study, an analytical function (DSCN(T)) has been developed based on an assumed Arrhenius crystal size distribution together with instrumental and sample-related peak broadening. The DSCN(T) function was successfully applied to fit the experimental data of a substantial number of calibration and new unknown samples, including samples with an obvious asymmetry of the melting peak, yielding the thermal characteristics such as melting and glass transition temperature, and enthalpy and heat capacity change. It also allows very accurate analysis of binary systems with two distinct but severely overlapping peaks and samples that include a cold crystallization before melting. [ABSTRACT FROM AUTHOR]

The manufacture of flexible devices is of immense interest due to their eco-friendliness, economic prospects and wide range of applications in biocompatible devices. Therefore, this paper reports the characterization and properties of chlorinated natural rubber (Cl-NR)/polyindole (PIN) blend with different contents of nickel oxide (NiO) nanoparticles. The formation of blend nanocomposites was analysed by FT-IR, UV spectroscopy, XRD, FE-SEM, DSC and TGA. The FT-IR and UV spectra proved the effective interfacial interaction between nanoparticles and the blend matrix, with a shift in UV peak intensity with the attachment of NiO at 433 cm−1. The XRD pattern revealed the regular arrangement of the blend matrix due to the presence of nanofiller, resulting in the semicrystalline structure of the composite system. The SEM micrographs revealed a homogeneous distribution of NiO in the blend matrix. The increased degradation temperature in the TGA demonstrated the enhanced thermal stability of the NiO-filled Cl-NR/PIN blend. DSC results showed that the glass transition temperature of the composite increased with NiO content in the blend matrix. The dielectric properties and AC electrical conductivity increased significantly with increasing temperatures, as well as with the addition of nanoparticles up to 5 mass % loading. The inclusion of NiO improved the tensile strength and hardness while reducing the elongation-at-break of nanocomposites. The blend nanocomposite with enhanced thermal stability, glass transition temperature, tensile strength, AC conductivity and dielectric properties enables them to be used in highly flexible electronic applications where traditional elastomeric materials fall short. [ABSTRACT FROM AUTHOR]

In this work, the effect of uniaxial stretching on the crystallization and melting behaviors, miscibility, crystal structure, and mechanical properties of neat poly(L-lactide) (PLLA) and miscible PLLA/poly(vinyl acetate) (PVAc) blends was investigated. Stretching process could generate remarkable influence on thermal properties of neat PLLA and PLLA/PVAc blend. With stretching ratio increasing, macromolecular chains orientation and crystallization were promoted, resulting in a decrease in cold crystallization temperature and an increase in glass transition temperature, and a significant increase in crystallinity. In addition, after stretching process PVAc still inhibited the crystallization of PLLA. PLLA/PVAc blends were completely miscible blend system which had only one glass transition temperature before and after stretching process, and phase separation did not occur after stretching process. When stretch ratio increased, amorphous PVAc had greater influence on the tanδ transition peak and storage modulus increased markedly, which was benefit to the improvement of heat resistance. The α′ crystal form was produced in blends after stretching process. Stretching process with moderate stretch ratio can be utilized to improve the mechanical properties of PLLA with simultaneous enhancement of tensile strength, fracture strain and stiffness. The findings in this work provide an insightful understanding of the effect of stretching process on miscible PLLA blend and the improvement of toughness, which will facilitate the large-scale practical application of PLLA. [ABSTRACT FROM AUTHOR]

Present embodiment is an account of work done on impregnation of thermoplastic polyether imide (PEI) [ULTEM 1000] into high-temperature biphenyl-based phthalonitrile (PN) thermosetting resin to form a semi-interpenetrating network (s-IPN) in order to find an optimum composition with little compromise on glass transition temperature (Tg) and thermal stability of base resin system. The PEI has been cured with PN resin in varied ratios of 5–30 mass% in arithmetic progression to study its effect on thermal and physical properties. Fourier transform infrared spectroscopy, differential scanning calorimetry and thermos-gravimetric (TG) measurements of the s-IPN compositions were carried out to assess the extent of curing, curing enthalpy, glass transition (Tg), thermal stability and char yield, respectively. The dynamic mechanical analysis (DMA), measurements were done to ascertain the effect of PEI component in PN system on its storage modulus, Tg under dynamic load with respect to temperature. PN95 composition having PN/PEI ratio in 95:05 stoichiometry has demonstrated the best desirable properties with respect to PEI content with least compromise in Tg temperature. More than 5 mass% PEI has resulted in drastic change in Tg of s-IPN from > 673 K to 525 K in case of 10 mass% PEI as evaluated by DMA. The morphological analysis of 30% PEI-containing s-IPN showed interesting cross-linked patterns probably formed by the fibrillar orientation of the thermoplastic resin in the PN matrix. [ABSTRACT FROM AUTHOR]

The aim of this work was to improve mechanical properties of a biocomposite of polylactic acid (PLA) reinforcing with fibrillated methacrylate-silanized hemp fibre. The effect of hemp fibre on photo-oxidation and hydrolytic degradation of PLA was evaluated through a QUV accelerated weathering test. Incorporation of 20 mass% fibre filler into neat PLA matrix resulted in increased tensile and flexural modulus for 150% and 200%, respectively. The outdoor degradation of neat PLA and PLA biocomposites was simulated in a 30 days of QUV accelerated weathering test in accordance with ISO 11507 method B. Glass transition temperature (Tg) was periodically recorded to measure the rate of degradation. Differential scanning calorimetry (DSC) analysis indicated that the degradation rate of the PLA matrix of the biocomposites tended to decrease proportionally to exposure time. The statistical regression method revealed a linear relationship between ln(Mn) and lnTg (R2 = 0.96). The 20 mass% hemp/PLA biocomposite was mostly destroyed over neat PLA after 30 days. The rate of degradation tended to have a linear proportion with hemp content. The results of FTIR 13C-NMR analysis confirmed that the substantial degradation of hemp/PLA biocomposites was due to the lignin content of the hemp fibre. The sensitivity of the PLA biocomposite to UVB light and moisture absorption accelerated photo-oxidation and hydrolytic degradation to the lowest molecular weight of PLA. [ABSTRACT FROM AUTHOR]

Natural brightness of epoxy adhesives can be reduced by adding cork. Besides, when cork was magnetized, it was possible to move them depending on the properties required in each section of the adhesive bond (PAT354/2019). The main objective of this work was to study possible changes in the thermal properties of the adhesive due to the addition of magnetic cork particles. If changes were significant, the use of magnetic cork particles would be compromised. To this end, natural cork particles and magnetic cork particles, with two different particle size (53–38 and 250–125 μm) and percentage (1 and 5 v/v%), were compared as reinforcement material. Magnetic cork was obtained by co-precipitated coating, according to patent number WO2019025651. The thermal properties studied by Differential Scanning Calorimetry were activation energy of curing reaction, glass transition temperature (Tg) and thermal conductivity. Two different hardeners were studied and a factorial design (2k with k = 4) was carried out. It allowed to determine which variable or combination of variables had most impact on thermal properties. Results showed that the main parameter affecting thermal properties was the hardener, regardless of the kind of particle used. However, the presence of magnetic cork highlights further the differences found between hardeners. The conclusion of this study was that magnetic cork particles can be used as fillers in epoxy resin to make graded joints, since they do not affect the thermal properties of the resin. [ABSTRACT FROM AUTHOR]

The structural and thermal properties of sodium niobium phosphate glass are studied to analyse its suitability for immobilizing long-lived radioactive waste from nuclear reprocessing plants. Two series of sodium niobium phosphate glasses such as (A) xNb2O5–(50−x)Na2O–50P2O5 and (B) xNb2O5–(50−x/2)Na2O–(50−x/2) P2O5 (x = 0, 10, 20, 30, 40 mol.%) are prepared by the conventional melt–quenching technique. The influence of the incremental addition of Nb2O5 on the structural and thermal properties of the above two series is investigated. The FTIR and Raman spectra of these glasses revealed that the number of [NbO6] octahedral chain increases with Nb content and dominates as the major structural unit over the number of PO4 tetrahedra unit. The glass transition temperature (Tg), crystallization temperature (Tc) and melting temperature (Tm) are measured by using a differential scanning calorimeter (DSC). Other thermal stability parameters such as Hruby (KH), Angell (KA), Saad–Poulain (KSP) and Weinberg (KW), the total relaxation time of transformation and fragility are evaluated and compared between different composition of glasses. For both series A and B, the glass transition temperature increases with Nb content, suggesting the formation of a larger number of P–O–Nb or Nb–O–Nb linkages compared to the PO4 tetrahedra, resulting in a more rigid network. This is confirmed by Raman spectra which show an increase in the number of Nb–O–Nb bonds with Nb content. The major crystalline phases formed by devitrifying these glasses are identified by XRD and are found to be mainly NaPO3, NbOPO4, Na2Nb6P4O26 and Na4Nb8P4O32. [ABSTRACT FROM AUTHOR]

The study of the P3HT synthesis was carried out to investigate the effect of reaction time on thermal, optical, electronic, and morphological properties. It has been demonstrated that the variation in polymerization time over 30 min did not significantly affect the optoelectronic properties of polymers. Regarding the thermal properties, the P3HT synthesized in the shortest time presented a decomposition temperature of 20 K higher than the others. There was no difference in glass transition temperature or melting temperature, while both crystallization temperature and crystallinity content have slightly increased with polymerization time. The regioregularity of all polymers was 98%. The advantage is that a short reaction time is possible to obtain a polymer with suitable properties and, consequently, savings in the process. P3HT-30 was evaluated in a PSC active layer with the configuration of ITO/PEDOT: PSS/rrP3HT:PC71BM/Ca/Al, and PCE was 1.94%. [ABSTRACT FROM AUTHOR]

Epoxy asphalt bond coat (EABC) is one of the thermosetting polymer-modified asphalts, which has been widely employed as a strong waterproof bonding layer between the asphalt concrete and the orthotropic steel bridge deck. In the present work, the influences of asphalt content on the phase separation, viscosity, thermal stability, viscoelastic behavior, mechanical performance, pull-off strength, and adhesive performance of EABCs were characterized by various instruments. Laser scanning confocal microscopy observations showed that phase separation occurring in EABCs depended on the curing time. The asphalt merged to form large spherical particles in the continuous epoxy phase during the cure reaction. The size of asphalt particles increased in the asphalt content. Viscosities of EABCs were higher than that of the pure epoxy and increased with the asphalt content in the initial curing stage. However, the opposite trend was observed in the latter curing stage. The presence of asphalt slightly improved the glass transition temperature and the damping properties of the pristine epoxy. For EABCs, the damping behaviors slightly increased with the asphalt content. The thermal stability of the pristine epoxy was enhanced by the incorporation of asphalt. The addition of asphalt decreased the mechanical, adhesive properties, and pull-off strength of the pristine epoxy. What's more, these properties of EABCs decreased in the asphalt content. [ABSTRACT FROM AUTHOR]

The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was used to prepare biocompatible composites modified by the hemp fibers. The aim of the study was to assess the structure and selected thermal and mechanical properties of the obtained biocomposites. The morphology of samples was analyzed using a scanning electron microscope and a computed tomography analysis. The phase transitions of composites and polymer matrix were investigated using differential scanning calorimetry. Moreover, the non-equilibrium and equilibrium thermal parameters of composites and the unfilled PHBV were established based on the thermal history. Knowing equilibrium parameters, i.e., the heat of fusion for the fully crystalline materials, ΔHf (100%), and the change of heat capacity at glass transition temperature (Tg) for the fully amorphous, ΔCp (100%), composites, the degree of crystallinity, mobile, and rigid amorphous fractions were estimated. The addition of hemp fibers to the PHBV matrix caused around a two-time increase in the degree of crystallinity in reference to the unfilled PHBV. It was also observed that the addition of hemp fibers caused a decrease in heat capacity for fully amorphous material for all the biocomposites obtained. A similar relationship was observed in case of values of the heat of fusion for fully crystalline material. Simultaneously, the decrease in amorphous phase contents was noted. It was also noted that the rigid amorphous fraction exists only for the unfilled polymer matrix. Some mechanical properties of investigated materials were also measured and presented. [ABSTRACT FROM AUTHOR]

Lignin-based polycaprolactone (PCL) graft copolymers with various graft ratios were prepared by ring-opening reaction in order to design new lignin derivatives. Molecular length of PCL side chain was varied in a wide range, i.e. caprolactone/hydroxyl group (CL/OH) ratio was varied from 3 to 100 mol mol−1. The effect of lignin on thermal properties of PCL was examined by differential scanning calorimetry (DSC) and thermogravimetry. In DSC heating curves of lignin-based PCL, glass transition, pre-melt crystallization and melting were observed. From DSC results, the phase diagram of lignin-based PCL was established. It was found that glass transition temperature (Tg) decreased until CL/OH ratio reached 20, and then, Tg was maintained at around 200 K. Tg slightly increased when CL/OH ratio became higher than 20. The above facts suggest that the random structure of lignin affects the molecular motion of copolymers in a limited length of PCL chains, and that with increasing PCL chain length, free molecular motion is restricted by crystallization. The amorphous region of lignin–PCL was reorganized at pre-melt crystallization, and crystallinity increased. When CL/OH ratio increased more than 20, two melting peaks were observed; the low-temperature side is PCL crystallite affected by lignin and the high-temperature side melting peak is attributed to melting PCL crystal. The effect of lignin on thermal decomposition is apparently observed for lignin-based PCL when CL/OH ratio is smaller than 20. The above results suggest that lignin-based PCL graft copolymers have the potential of an applicant of novel nature-friendly polymers. [ABSTRACT FROM AUTHOR]

Iron phosphate glasses are materials that can have many applications like durable matrixes in waste immobilization techniques, biomaterials, optoelectronic devices, etc. Their possible usage is related to their glass network and thermal properties. The influence of Na2O content on thermal properties and crystallization ability of iron phosphate glass of base composition 30 Fe2O3–70 P2O5 mol% were studied. Increasing the content of Na2O causes a decrease in transformation temperature and increase in ΔCp. Characteristic temperatures, thermal stability and crystallizing phases were determined. Increasing content of sodium causes depolarization of iron phosphate glass network which causes a continuous change in ΔCp and glass transformation temperature. Discontinuous change in some glass properties suggests structure rebuilding about 30 mol% of Na2O. [ABSTRACT FROM AUTHOR]

In this study, new thermoplastic sulfur-containing poly(carbonate-urethane)s (PCURs) were synthesized via a one-step melt polyaddition from diphenylethane-derivative diols with two or ten methylene groups in the aliphatic chain, i.e., 4,4′-(ethane-1,2-diyl)bis(benzenethioethanol) (diol E) and 4,4′-(ethane-1,2-diyl)bis(benzenethiodecanol) (diol D) as nonconventional chain extenders, 1,1′-methanediylbis(4-isocyanatobenzene) and 20–60 mol% poly(hexane-1,6-diyl carbonate) diol of M ¯ n = 860 g mol−1 as a soft segment. The PCURs were studied mainly to describe their thermal and mechanical behaviors by means of DSC, TG and TG coupled with FTIR, and Shore hardness and tensile tests. Moreover, their structure and physicochemical and adhesive properties were determined. The results of the study showed that the kind of the chain extender as well as soft-segment content had an impact on the properties of the polymers obtained. They were amorphous or semicrystalline high molar mass materials. The PCURs based on diol D exhibited lower glass transition temperatures in comparison with those based on diol E with shorter aliphatic chain (− 1–24 °C vs. 13–55 °C). Unfortunately, the former polymers revealed somewhat poorer tensile strengths (up to 45.0 MPa vs. 51.8 MPa). Nevertheless, these values were similar to or higher than those obtained for their commercial analogs. The PCURs being diol D derivatives also showed, in general, lower hardness and the modulus of elasticity but higher elongation at break. All the PCURs exhibited a relatively good thermal stability. However, the polymers derived from diol D revealed higher temperatures of 1, 10 and 50% mass losses compared with diol E-based ones (290–298 °C vs. 285–287 °C, 325–336 °C vs. 314–323 °C, 360–381 °C vs. 348–356 °C, respectively). The newly synthesized sulfur-containing PCURs showed better adhesive properties to copper than the analogous polymer based on butane-1,4-diol as a chain extender. [ABSTRACT FROM AUTHOR]

The influence of blending ratio and trifluoropropyl polyhedral oligomeric silsesquioxane (POSS) on microstructure, melt and cold crystallization behavior, thermomechanical and thermal stability of melt-blended polylactic acid/thermoplastic polyurethane (PLA/TPU) blends was investigated using various techniques. Morphological observations (TEM and EDX) showed that POSS nanoparticles have a good dispersion state throughout the matrix and localize in both phases and also at the blend interface. POSS nanoparticles hindered the melt crystallization of PLA while enhancing the degree of cold crystallinity of PLA. In addition, the dispersed TPU droplets in PLA matrix induced a nucleation effect on melt crystallization of PLA, especially at low contents. On the contrary, the cold crystallization temperature of PLA shifted to a higher temperature in the presence of TPU phase, but the degree of crystallinity improved in the case of heating with a low rate. Although the addition of TPU to PLA resulted in a decrement in onset degradation temperature, the samples degraded in wider ranges than neat PLA. The onset degradation temperature of samples in inert ambient was declined by the addition of POSS due to its low thermal stability. These nanoparticles slightly enhanced the thermal stability of PLA-rich samples in air ambient but had no sensible effect on TPU-rich samples. The storage modulus values of the PLA/TPU blends gradually decreased with increasing TPU content. In addition, incorporation of POSS nanoparticles, generally, increased the values of storage modulus but reduced the glass transition temperature, proving the lubrication effect of POSS nanoparticles. [ABSTRACT FROM AUTHOR]

In this work, aliphatic starting reactants were used to prepare a series of polycarbonate-based polyurethane (PC-PU) nanocomposite films with a low amount of titanium dioxide (TiO2) nanoparticles (0.5, 1.0 and 2.0%) by one-step technique. The influence of nanoparticles on the structure and hydrogen bonding, as well as the microphase and topography of the obtained hybrid materials was followed by Fourier transform infrared spectroscopy, Atomic force microscopy and Scanning electron microscopy coupled with energy-dispersive X-ray Spectroscopy, respectively. Thermogravimetry was performed to study the effect of TiO2 on the thermal stability and the decomposition pattern of the obtained PC-PU films. The impact of TiO2 on the glass transition temperature, relaxation of soft domains as well as the melting of hard segments was determined by modulated differential scanning calorimetry. The significant enhancement of thermal stability and degradation of prepared hybrid materials were achieved, due to increased hydrogen bonding by addition of TiO2. The glass transition temperatures of all PC-PU films were found independent on the titanium dioxide mass fraction. The starting of physical cross-linking disruption of the obtained hybrids was registered at significantly higher temperatures, as a consequence of the achieved interaction between uniformly dispersed TiO2 nanoparticles and hard phase. [ABSTRACT FROM AUTHOR]

Zinc phosphate–germanate samples doped with Er3+ ions and co-doped with silver nanoparticles in the 59.7KPO3–0.3Ag(NPs)–20ZnO–(20 − x)GeO2–xEr2O3 system where x ≤ 5 mol% were prepared by melting–quenching technique. The mentioned system was studied by X-ray diffraction (XRD), differential thermal analysis (DTA) and ultraviolet–visible (UV–Vis) spectroscopy, too. XRD analysis shows the presence of amorphous state for low contents of erbium and the presence of the ErPO4 (tetragonal, body-centered lattice) crystalline phase beside the amorphous phase for high contents of erbium (x ≥ 3 mol%). DTA investigation permitted the identification of some thermal parameters such as glass transition temperature, crystallization temperature and melting temperature. From these data, other two important parameters were calculated: the fragility index and the activation energy of glass transition. In our case, the obtained data reveal a good thermal stability for the matrix of the studied system. The increase in the content of erbium ions leads to more fragile glasses and glass ceramic samples. The DTA results also show that the samples are obtained from KS liquids. The UV–Vis spectroscopy shows seven f–f electronic transitions for the studied system, due to the presence of erbium ions. From the obtained UV–Vis data, the bonding parameter that shows an ionic character of the bonds from the glass ceramic network was calculated. Also, the values of optical band gap energy ( E g opt ) show that when the erbium ions content increases, the E g opt values decrease due probably to the amount of non-bridging oxygen atoms from the network. [ABSTRACT FROM AUTHOR]

Different types of phosphorus containing halogen-free flame retardants (FRs) were added to an epoxy-dicyandiamide resin formulation in order to study to which extent they affect its glass transition temperature (Tg), tensile properties, thermal stability and burning behavior of the resin. For this purpose, an additive-type FR (ammonium polyphosphate encapsulated in melamine resin, MAPP) and two reactive-type FRs i) a commercial epoxy resin pre-reacted with 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide, (DOPO), and ii) a phosphorus containing hardener (poly(m-phenylene methylphosphonate), (PMP) were used. It was observed that the addition of additive-type FR did not affect in great extent the Tg and provided a V-0 rating in UL94 test at low loadings. The addition of reactive-type FRs (DOPO and/or PMP), however, modified the structure of the chain network resulting in lower crosslink density as a consequence of their higher equivalent mass, but achieving also with low PMP content V-0 rating. [ABSTRACT FROM AUTHOR]

Phase behavior of twenty-one synthesized salts of triethanolammonium(tris (2-hydroethyl)ammonium) has been studied by the methods of differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). It has been established that 18 of them are protic ionic liquids (PILs) with Tm < 100 °C, and 3 are molten salts with Tm > 100 °C. The PILs have been divided into three groups according to their phase behavior in the DSC experiment. The phase behavior of each of the studied ionic liquids has been analyzed. Multiple regression has been obtained between the ionic liquids characteristics (such as melting, glass transition and decomposition temperatures) determined experimentally and the properties of the anions of the acids forming the PILs calculated by the quantum chemistry methods. It has been shown that there is a linear compensation effect between the changes in the entropy and enthalpy caused by triethanolammonium salts melting. [ABSTRACT FROM AUTHOR]

Barium phosphate glasses of the composition (100 − x)Ba(PO3)2–xWO3 with 0–60 mol% WO3 were prepared and studied. Thermal studies of the glasses were carried out with DTA, dilatometry and hot-stage microscopy. Glass transition temperature in this glass series increases with increasing WO3 content from 461 °C (x = 0) to 623 °C (x = 60). Most glasses containing WO3 crystallize on heating within the range of 650–750 °C with the exception of glasses with 20–30 mol% WO3, which are thermally stable. Very high chemical durability of these glasses with dissolution rate of 1.4 × 10−8–6.2 × 10−9 g cm−2 min−1 was also revealed. Crystallization of glasses revealed the existence of a new compound Ba(WO2)2(PO4)2 in the studied compositional series. The compound Ba(WO2)2(PO4)2 possess hexagonal unit cell of dimensions a = 11.5191(1) Å and c = 6.3437(1) Å, and its melting point is 936 °C. Raman spectra of crystallized glasses confirmed the formation of crystalline compound in this glass series and revealed the presence of glass phase in some thermal-treated samples. 31P MAS NMR showed on only one coordination of phosphorus atoms in the Ba(WO2)2(PO4)2 compound. [ABSTRACT FROM AUTHOR]

Soybean oil-based polyurethane (PU)/epoxy (EP) interpenetrating polymer network (IPN) nanocomposites were prepared with natural attapulgite (N-ATT) and acid-treated attapulgite (A-ATT). The structure, glass transition, damping properties, thermal stability, mechanical properties and morphology of PU/EP IPN/ATT nanocomposites were characterized by X-ray diffraction (XRD), dynamic mechanical analysis (DMA), thermogravimetric analyzer, universal test machine and scanning electronic microscope (SEM). XRD showed that interaction with PU did not change the crystal structures of ATT. DMA results revealed the addition of ATT improved the glass transition temperature of the soybean oil-based PU/EP IPN, especially for A-ATT. However, the incorporation of ATT slightly decreased the damping properties of the soybean oil-based PU/EP IPN. Tensile tests confirmed that A-ATT had a significant reinforcement effect on the soybean oil-based PU/EP IPN. The tensile strength of the soybean oil-based PU/EP IPN increased by 56% with the addition of 4 mass% A-ATT. SEM demonstrated the relatively uniform dispersion of both N-ATT and A-ATT in the soybean oil-based PU/EP IPN matrix. [ABSTRACT FROM AUTHOR]

In this study, oleo-gum resin obtained from wild pistachio trees (Pistacia atlantica Desf. Subsp. kurdica), known as Saqez, was used as a biodegradable, biocompatible, natural, and edible chewing gum. Saqez was characterized by ash content, texture profile analysis, and differential scanning calorimetry (DSC). Furthermore, Saqez was also compared to commercial chewing gum samples. The total ash content was found highest in chewing gums followed by Saqez. Moreover, all texture parameter values of Saqez were lower than conventional chewing gums. The analysis of DSC in Saqez confirmed that the glass transition temperature was comparable to commercial chewing gums. Saqez gum was seen to be an ideal replacement for a synthetic gum base in the manufacturing of a commercial chewing gum. The present study offers new information on Saqez gum, which will be precious and useful for explaining its unique textural properties and thermal behavior in the area of food science and technology. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC), dilatometry and X-ray diffraction have been used to study thermal behavior and stability of glasses prepared simultaneously in Al2O3 or Pt crucibles in compositional series (40 − x)MgO-xFe2O3-60P2O5 within the concentration range of x = 0-40 mol% Fe2O3. Mössbauer spectra showed that all glasses with Fe2O3 contained both Fe(II) and Fe(III) ions. The contamination glasses from alumina crucibles ranged from 0.3 to 0.9 mol% Al2O3. The replacement of MgO by Fe2O3 resulted in a gradual decrease in glass transition temperature and dilatometric softening temperature, whereas thermal expansion coefficient did not change significantly. The DSC curves showed that all glasses crystallize on heating in the broad temperature range ≈ 560-900 °C. Crystallization temperature decreases with increasing Fe2O3 content. The highest tendency toward crystallization was found for the glass containing 40 mol% Fe2O3. X-ray diffraction measurements showed that the major compounds formed by glass crystallization were Mg(PO3)2, Fe(PO3)3, Fe3(P2O7)2 and FePO4. All thermoanalytical studies showed differences in thermal behavior of glasses prepared in Al2O3 or Pt crucibles. [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]

In the study, MDSC method was used to evaluate thermal properties of β-lactoglobulin-retinyl palmitate products enriched in disaccharides. Additionally, sorption behavior of powders was determined to define their stability. The obtained powders were also examined and visualized with scanning electron microscopy to find the relationship between food processing conditions and morphological changes in products. For the samples tested, a single glass transition was observed. The results have shown the impact of the composition of studied samples on the glass transition temperatures. The carbohydrate- β-lactoglobulin systems were characterized by higher T values than disaccharides alone. At low water activity, all powdered complexes showed typical sorption behavior of food systems with the sigmoidal shape of the curve. The present study has shown that spray-dried and freeze-dried powdered products with lactose or trehalose have different time-dependent crystallization behavior. Trehalose as a carbohydrate component of samples, in comparison with lactose, delayed the occurrence of crystallization. The obtained images presented the dependence of the shape of the particles on the drying method used. Spray-dried powders were characterized by a spherical or close to spherical structure with the surface of larger particles often deformed. In the case of freeze-dried particles, irregular structures were observed. [ABSTRACT FROM AUTHOR]

Several composites and nanocomposites based on a polymeric matrix and ceramic fillers are being pursued for use as multifunctional and innovative materials. Nevertheless, there is a series of challenges to be solved in this area such as the understanding of the role of interfaces and the synergy between matrix and fillers. In this work, vulcanized natural rubber nanocomposites were prepared with different concentrations of two kinds of ceramic nanoparticles, potassium strontium niobate (KSrNbO or KSN) and nickel-zinc ferrite (NiZnFeO or NZF), synthesized by a chemical method known as the modified polyol method. Morphological and thermal characterizations were carried out by AFM, TG/DTG, TG/FTIR and DSC. The thermal properties of nanocomposites were compared and discussed as functions of concentration, type and surface of nanoparticles. The results obtained suggest that the base concentration for both types of nanoparticles inside the polymer matrix volume greatly adds to the increase in thermal stability up to 11 % and the glass transition temperature up to 10 °C. A similar evolution for the glass transition temperature ( T ), thermal stability temperature ( T ) and dielectric permittivity ( ε′) was identified, suggesting that these phenomena are mainly dominated by the same mechanisms. These results point to the possibility for the thermal parameter modulation in magnetic and ferroelectric nanocomposites by means of a suitable control of concentration and properties of the KSN and NZF nanoparticles. [ABSTRACT FROM AUTHOR]

Borophosphate glasses of the BaO-BO-PO ternary system were prepared and studied within the large glass-forming region of the system. Fourteen investigated glass samples of barium borophosphate glasses were discussed for a comparison of the compositional trends in their properties in four compositional series such as A: (100 − x)Ba(PO)- xBO, B: 40BaO- yBO-(60 − y)PO, C: (50 − z)BaO- zBO-50PO, and D: (60 − w)BaO- wBO-40PO. Changes in glass density and molar volume primarily depend on the BaO content in the glasses. The thermal properties were studied with a differential thermal analysis, hot-stage microscopy, and dilatometry. Glass transition temperature increases with a rising BO content most rapidly in the glass series A and B. It reaches its maximum in these series for the glasses containing 20-30 mol%, where the glass network represents a 3D structure interlinked with P-O-B, P-O-P, and B-O-B bridges. The thermal expansion coefficient decreases, in contrast, with the increasing BO content in these ternary glasses as well as their chemical durability. The crystallization of these glasses, in the samples with a low BO content, results in the formation of barium metaphosphate BaPO. Certain crystallized samples also contain a small amount of BPO, and diffraction lines of ternary compounds BaBPO and BaB(PO) were revealed in a number of samples. A new compound of the composition BaBPO was identified in the crystallized glass 50BaO-10BO-40PO. [ABSTRACT FROM AUTHOR]

The thermal and mechanical properties of polystyrene (PS) modified with esters derivatives of 3-phenylprop-2-en-1-ol were investigated. The influence of the content of esters on the glass transition temperature, dynamic mechanical properties, flexural properties, hardness and thermal stability of PS has been examined. It was found that the PS/ester compositions were characterized by lower stiffness, lower values of T, lower hardness, lower stress at break, lower thermal stability and higher values of tg delta height and strain at break as compared to pure PS. The obtained results proved that esters derivatives of 3-phenylprop-2-en-1-ol can find their place as an environmentally friendly, external plasticizers of PS. [ABSTRACT FROM AUTHOR]

Polycarbonate (PC)/Zinc oxide (ZnO) nanocomposite films were prepared by a solution mixing method and irradiated by Swift heavy ion at various ions fluences ranging from 1 × 10 to 3 × 10. The surface morphological, structural, and thermal properties of untreated and irradiated PC/ZnO nanocomposite films were investigated by various characterizations techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry, Thermogravimetric (TG) and Thermally stimulated discharge current (TSDC). The XRD pattern reveals that the average crystallite size and percentage of crystallinity decreases with increase of ion fluences. TSDC measurement is an evidence of different type of relaxation process. The activation energy released charge and charge carrier mobility for α-relaxation peak decreases, while relaxation time and peak current increase. TG measurement shows thermal stability and mass loss decreases with ions fluences. FTIR spectra reveal the position of different bonds in PC and nanocomposite films. The glass transition temperature of nanocomposites is observed to be decreases with ion fluences. [ABSTRACT FROM AUTHOR]

A new series of four different linear aliphatic ether linked aromatic bismaleimides (AEBMIs) were synthesized from the respective linear aliphatic ether-linked aromatic diamines and maleic anhydride. Further, the POSS-AEBMI nanocomposites were developed by Michael addition reaction of bismaleimide with varying mass percentages of octa(aminophenyl)silsesquioxane and were characterized by the fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Data from thermal studies revealed that the POSS-reinforced AEBMI nanocomposites possesses higher glass transition temperature ( Tg), thermal stability, limiting oxygen index, and lower dielectric constant when compare to that of neat AEBMI. X-ray diffraction and transmission electron microscopy analysis confirmed the molecular level dispersion of POSS in the AEBMI matrix. [ABSTRACT FROM AUTHOR]

The paper concerns thermal properties of epoxy/nanotubes composites for aircraft application. In this work, influence of carbon nanotubes on thermal stability, thermal conductivity, and crosslinking density of epoxy matrix was determined. Three kinds of nanotubes were used: non-modified with 1- and 1.5-μm length, and 1-μm length modified with amino groups. Scanning electron microscopy observations were done for examining dispersion of nanotubes in the epoxy matrix. Glass transition temperature ( T) was readout from differential scanning calorimetry. From dynamic mechanical analysis, crosslinking density was calculated for epoxy and its composites. Also, thermogravimetric analysis was done to determine influence of nanotubes addition on thermal stability and decomposition process of composites. Activation energy was calculated from TGA curves by Flynn-Wall-Ozawa method. Thermal diffusivity was also measured. SEM images proved the uniform dispersion of carbon nanotubes without any agglomerates. It was found that nanotubes modified with amino groups lead to the increase of epoxy matrix crosslinking density. The significant increase in T was also observed. On the other hand, addition of carbon nanotubes leads to the decrease of thermal stability of polymer due to the increase of thermal diffusivity. [ABSTRACT FROM AUTHOR]

The thermo-physical properties of diglycidyl ether of bisphenol A (DGEBA)/isophoronediamine (IPDA) with iron nanoparticles were investigated using DSC, DMT, and TG analysis. Because of the higher values of the glass transition, it is recognized that the optimum behavior of the three-component system corresponds to the 10% loading level of iron nanoparticles. The addition of iron nanoparticles into the epoxy matrix resulted in a significant increment in the storage modulus and crosslink density. Also, the DGEBA/IPDA/10% iron nanoparticles showed an enhanced thermal stability owing to the introduction of iron nanoparticles as reinforcing filler. Curing reaction of DGEBA/IPDA with 10% iron nanoparticles was investigated by DSC at dynamic mode. Activation energy was calculated based on Kissinger method (66.52 kJ mol). Also, the advanced isoconversional method is utilized to describe the curing reaction process. In the dynamic DSC analyses, the curing kinetics could be successfully described with the two-parameter autocatalytic model (Sěsták-Berggren equation) and the overall reaction order was about 2.78. [ABSTRACT FROM AUTHOR]

Copolymers of p-nitrobenzyl acrylate and diisopropyl fumarate with different feed ratios were synthesized under microwave and thermal heating conditions, and then characterized by IR, H-, and C-NMR spectroscopy. Average molecular weights were analyzed by size exclusion chromatography (SEC). Monomer reactivity ratios were obtained from an extended Kelen-Tüdös method. Differential scanning calorimetry and thermogravimetry were used to evaluate the thermal behavior of all copolymers synthesized under microwave energy. Based on the products analyzed by SEC and gas chromatography-mass spectrometry, a possible mechanism of degradation is postulated. [ABSTRACT FROM AUTHOR]

New branched polymethylvinylborosiloxanes (PMVBSs) with random structures were prepared, and their chemical structures were studied by spectroscopic methods (FTIR, H-, Si-, and B-NMR) and elemental analysis (% C, % H, % Si, and % B). Average molecular weights M and M were determined by a size exclusion chromatography (SEC), and dynamic viscosities were measured in Brookfield cone-plate reoviscometer HBDV-II+cP. Thermal properties of PMVBSs were studied under air and under nitrogen atmosphere. Thermal curves were interpreted from the point of view of physical and chemical transitions, taking place during the heating process of PMVBSs. Parameters of their thermal stabilities and glass transition temperatures ( T) were determined. The synthesized PMVBSs are characterized by low glass transition temperatures ( T: from −122 to −137 °C) which depend on their chemical structures. It was concluded that gaseous products (such as volatile siloxanes, silanes, CO, HO, CHO, methanol, and formic acid), which could be liberated during the heating process of PMVBSs, promote ceramization processes, leading to the formation of the ceramics of a type SiBCO-a borosilicate glass and silica. [ABSTRACT FROM AUTHOR]

The effect of TeO additions on the thermal behaviour of zinc borophosphate glasses were studied in the compositional series (100 − x)[0.5ZnO-0.1BO-0.4PO]- xTeO by differential scanning calorimetry, thermodilatometry and heating microscopy thermal analysis. The addition of TeO to the starting borophosphate glass resulted in a linear increase of glass transition temperature and dilatometric softening temperature, whereas the thermal expansion coefficient decreased. Most of glasses crystallize under heating within the temperature range of 440-640 °C. The crystallization temperature steeply decreases with increasing TeO content. The lowest tendency towards crystallization was observed for the glasses containing 50 and 60 mol% TeO. X-ray diffraction analysis showed that major compounds formed by annealing of the glasses were ZnPO, BPO and α-TeO. Annealing of the powdered 50ZnO-10BO-40PO glass leads at first to the formation of an unknown crystalline phase, which is gradually transformed to ZnPO and BPO during subsequent heating. [ABSTRACT FROM AUTHOR]

The 4,4,-oxydiphthalic anhydride-chitosan (ODAC) filler at composition of 2-12 wt/v% was selected to reinforce the Cs matrix by solution casting method. The thermal properties of the bio-composites were then evaluated by thermogravimetry analysis, differential scanning calorimetry, and dynamic mechanical analysis. The addition of ODAC filler in Cs matrix up to 10 wt/v% had increased the thermal stability of the bio-composites by increasing the thermal degradation ( T) and glass transition temperature ( T) of the bio-composites. Good interfacial bonds of electrostatic interactions and inter-hydrogen bonds of the bio-composite components significantly influenced the thermal properties of the bio-composites. [ABSTRACT FROM AUTHOR]

Thermal properties and degree of conversion (DC%) of two composite resins (microhybrid and nanocomposite) and two photo-activation methods (continuous and gradual) displayed by the light-emitting diode (LED) light-curing units (LCUs) were investigated in this study. Differential scanning calorimetry (DSC) thermal analysis technique was used to investigate the glass transition temperature ( T) and degradation temperature. The DC% was determined by Fourier transform infrared spectroscopy (FT-IR). The results showed that the microhybrid composite resin presented the highest T and degradation temperature values, i.e., the best thermal stability. Gradual photo-activation methods showed higher or similar T and degradation temperature values when compared to continuous method. The Elipar Freelight 2 LCU showed the lowest T values. With respect to the DC%, the photo-activation method did not influence the final conversion of composite resins. However, Elipar Freelight 2 LCU and microhybrid resin showed the lowest DC% values. Thus, the presented results suggest that gradual method photo-activation with LED LCUs provides adequate degree of conversion without promoting changes in the polymer chain of composite resins. However, the thermal properties and final conversion of composite resins can be influenced by the kind of composite resin and LCU. [ABSTRACT FROM AUTHOR]

The effect of a low profile additive, poly(ε-caprolactone) (PCL), on the thermal and mechanical properties of unsaturated polyester resins (UP) was investigated by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile tests. The morphology of the systems has been studied by scanning electronic microscopy (SEM). Two PCL molecular mass were selected (PCL2: M = 2000 g mol and PCL50: M = 50000 g mol) to analyze the influence of the molecular mass and the content of PCL on the UP resins and to establish the relation between thermomechanical behavior and morphology. DSC and DMTA glass transition temperatures ( T) of the UP cured samples containing PCL indicate that PCL2 is miscible with UP whereas for UP + PCL50 system, T values are very close to the ones corresponding to neat UP. Besides in UP + PCL2 systems, one phase morphology is observed in which PCL2 would act as solvent of the reacting mixture along curing process; however, UP + PCL50 systems present phase-separated morphology. The presence of PCL2 and PCL50 in UP resin leads to a decrease of the tensile strength and the Young′s modulus as much notorious as the PCL concentration increases. For UP + PCL2 system the elongation at fracture increases in relation to neat UP, increasing as well with the PCL content. [ABSTRACT FROM AUTHOR]

The results of thermal analysis of speciality elastomers CSM with different chlorine and sulphur contents is presented in the article. The thermal curves obtained under the atmosphere of inert gas have been interpreted from the point of view of phase transitions and chemical reactions of the examined polymers during their heating. It has been stated that from among the investigated chlorosulphonated polyethylenes, only CSM24, which has the lowest chlorine content, contains a crystalline phase, clearly influences on its T temperature. Results of the thermal analysis obtained under inert gas atmosphere have been compared with results obtained under termooxidative atmosphere. Irrespective of the research atmosphere, the thermal decomposition of investigated CSM takes place in three stages. The maximum rate of thermal destruction of modified by heating elastomers, d m/d t, decreases with the increase in chlorine content in the sample having been heated. [ABSTRACT FROM AUTHOR]

Epoxidized palm oil (EPO) (0–12 wt%) was added into petrochemical-based epoxy blends (diglycidyl ether of bisphenol-A (DGEBA)/cycloaliphatic epoxide resin/epoxy novolac resin) to develop a thermal curable bio-based epoxy system. The thermal behaviors of the EPO, epoxy blends (EB), and bio-based epoxy blends (EB/EPO) were characterized using differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMT) and thermo-mechanical analysis (TM). The glass transition temperature ( T) and storage modulus ( E′) of the EB/EPO system was reduced with the increasing of the EPO loading. This is attributed to the plasticizing effect of the EPO. It was found that epoxy blends with higher loading of EPO possessed higher coefficient of thermal expansion (CTE) and tan δ value. This is due to the increase of the free volume and chain flexibility in the three-dimensional network of the epoxy blends. The internal thermal stresses of the EB/EPO were decreased as the increasing loading of EPO, owing to the reduction of crosslink density, modulus of elasticity, and T in the epoxy blends. [ABSTRACT FROM AUTHOR]

Thermal behaviour and structure of glasses from the SiO–PO–KO–MgO–CaO system modified by FeO addition were studied by DSC, XRD and FTIR methods. It has been found that the replacement of MgO and CaO modifiers by FeO in the structural network of silicate–phosphate glass results in decrease of the glass transition temperature ( T) and heat capacity change (Δ C) accompanying the glass transformation. Simultaneously, the ability for crystallization, its course and the type of the forming phases depend on the relative proportions between iron and phosphorus as components forming the silicate–phosphate structure. The type of the crystal phases forming in the course of heating the considered glass has been found to be in agreement with the character of the domains occurring in this glass, confirmed by FTIR examinations. [ABSTRACT FROM AUTHOR]

Thermal properties of industrial hydrolysis lignin (HL) obtained from bio-ethanol production plants were investigated by thermogravimetry and differential scanning calorimetry. Thermal decomposition of HL was observed in two stages suggesting coexisting carbohydrates. Glass transition temperature ( Tg) was observed in a temperature range from 248 to 363 K. Tg values were lower than that of other industrial lignins, such as kraft lignin or lignosulfate. Enthalpy relaxation was observed as sub- Tg, which is not as prominent as other industrial or laboratory scale isolated lignins. Tg of HL decreased in the presence of water and saturated at water content ( Wc) of 0.18 (mass of water/mass of dry HL). The amount of bound water calculated from melting enthalpy of water and Wc was ca. 0.18. Thermal decomposition and molecular motion of as obtained industrial HL are affected by coexisting carbohydrates. [ABSTRACT FROM AUTHOR]

Temperature modulated differential scanning calorimetry (TMDSC) and dynamic mechanical analysis (DMA) are used to calculate cooperative rearranging region (CRR) average sizes for drawn poly(ethylene terephthalate) (PET) with different draw ratios (λ) ranging from λ=1 to 4, according to Donth’s approach. It is shown for both studies that the CRR size decreases when increases, due to the amorphous phase confinement by the crystals generated during the drawing. However, differences observed between the values calculated from TMDSC and DMA investigations are explained by the differences between a mechanical uniaxial dynamic solicitation (DMA) or a thermal solicitation (TMDSC) in terms of cooperative rearrangements at the glass transition. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) were used to study the thermal behaviour of (50- x)Na2O- xTiO2-50P2O5 and 45Na2O-yTiO2-(55- y)P2O5 glasses. The addition of TiO2 to the starting glasses ( x=0 and y=5 mol% TiO2) resulted in a nonlinear increase of glass transition temperature and dilatation softening temperature, whereas the thermal expansion coefficient decreased. All prepared glasses crystallize under heating within the temperature range of 300–610°C. The contribution of the surface crystallization mechanism over the internal one increases with increasing TiO2 content. With increasing TiO2 content the temperature of maximum nucleation rate is also gradually shifted from a value close to the glass transition temperature towards the crystallization temperature. X-ray diffraction measurements showed that the major compounds formed by glass crystallization were NaPO3, TiP2O7 and NaTi2(PO4)3. The chemical durability of the glasses without titanium oxide is very poor, but with the replacement of Na2O or P2O5 by TiO2, it increases sharply. [ABSTRACT FROM AUTHOR]

A thermal analysis of a series of polylactides (PLA) was carried out based on the number of average molecular mass ( Mn), and the nature of isomer ( D, L and DL). It is confirmed that the glass transition temperature ( Tg) of PLA increased as a function of molecular mass irrespective of isomer type except sample with a high polydispersity index. The melting temperature ( Tm) and enthalpy of crystal fusion (Δ Hf) of L-isomer increased as the Mn was increased from 1100 to 27500. The degree of crystallinity (χc%) increased as a function of molecular mass. However no crystallization peak was detected in the lower molecular mass range (550–1400). The non-isothermal crystallization behavior of the PLA melt was significantly influenced by the cooling rate. Both D and L isomers exhibited insignificant difference in thermal properties and DL lactides exhibited amorphous behavior at identical molecular masses. Change in microstructure showed significant difference between two isomers. Analysis of the FTIR spectra of these PLA samples in the range of 1200–1230 cm−1 supported DSC observation on crystallinity. [ABSTRACT FROM AUTHOR]

DTA was used to study thermal properties and thermal stability of (50- x)Li2O- xTiO2-50P2O5 ( x=0–10 mol%) and 45Li2Ot- yTiO2-(55- y)P2O5 ( y=5–20 mol%) glasses. The addition of TiO2 to lithium phosphate glasses results in a non-linear increase of glass transition temperature. All prepared glasses crystallize under heating within the temperature range of 400–540°C. The lowest tendency towards crystallization have the glasses with x=7.5 and y=10 mol% TiO2. X-ray diffraction analysis showed that major compounds formed by annealing of the glasses were LiPO3, Li4 P2O7, TiP2O7 and NASICON-type LiTi2(PO4)3. DTA results also indicated that the maximum of nucleation rate for 45Li2O-5TiO2-50P2O5 glass is close to the glass transition temperature. [ABSTRACT FROM AUTHOR]

In this study, the thermal properties of bio-flour-filled, polypropylene (PP) bio-composites with different pozzolan contents were investigated. With increasing pozzolan content, the thermal stability, 5% mass loss temperature and derivative thermogravimetric curve (DTGmax) temperatures of the bio-composites slightly increased. The coefficient of thermal expansion (CTE) and thermal expansion of the bio-composites decreased as the pozzolan content increased. The glass transition temperature ( T g), melting temperature ( T m) and percentage of crystallinity ( X c) of the bio-composites were not significantly changed. The thermal stability, thermal expansion and X c of the maleic anhydride-grafted PP (MAPP)-treated bio-composites were much higher than those of non-treated bio-composites at 1% pozzolan content due to enhanced interfacial adhesion. X-ray diffraction (XRD) analysis confirmed the crystallinity of pozzolan-added bio-composites. From these results, we concluded that the addition of pozzolan in the bio-composites was an effective method for enhancing the thermal stability and thermal expansion. [ABSTRACT FROM AUTHOR]

The addition of suitable cross-linking agents with norbornene-based monomers has significant effects on the thermal properties of the resulting polymers formed by olefin metathesis. Ethylidene norbornene (ENB) and endo-dicyclopentadiene ( endo-DCPD) were mixed separately with various loadings of three different cross-linking agents and then polymerized with the addition of Grubbs’ catalyst. The polymerization kinetics and resulting glass transition temperature ( T g) of the systems were evaluated by differential scanning calorimetry (DSC). The addition of the first cross-linking agent, norbornadiene (CL-1), to both endo-DCPD and ENB resulted in decreasing glass transition temperatures with increasing concentrations. In contrast, the addition of the other two cross-linking agents (CL-2 and CL-3), which were both custom synthesized bifunctional norbornyl systems, to both endo-DCPD and ENB resulted in a monotonic increases in T g with cross-linker concentration. By tailoring the loading of these custom cross-linking agents, the properties of these polymer systems can be controlled for various applications, including self-healing composites. [ABSTRACT FROM AUTHOR]

Polyamide-6-block-polybutadiene copolymers have been prepared by the anionic polymerization of ɛ-caprolactam in presence of α,ω-dihydroxy terminated polybutadiene. TG, Hi-Res™ TGA, DSC, TMDSC and DMA techniques have been applied. The suitability of the methods used to determine the content, thermal stabilities and glass transition temperatures of the components constituting the block copolymer is discussed. [ABSTRACT FROM AUTHOR]

Complex heat capacity, C p *= C p '– iC p '', of lithium borate glasses xLi2O·(1– x)B2O3 (molar fraction x=0.00–0.30) has been investigated by Modulated DSC. We have analyzed the shape of C p * by the Cole-Cole plot, performed fitting by the Havriliak-Negami equation, and then determined the parameters related to the non-Debye nature of thermal relaxation. Moreover, the concentration dependence of the thermal properties has been investigated. Glass transition temperatures become higher with the increase of molar fraction of Li2O and shows the board peak around x=0.26. Temperature ranges of glass transitions become narrower with the increase of Li2O concentration. [ABSTRACT FROM AUTHOR]