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Thermogravimetric Analyzer (thermogravimetric + analyzer)

Distribution by Scientific Domains

Polymers and Materials Science	83%

Selected Abstracts

In situ generated hydroxyl-terminated polybutadiene nanoparticles in polyimide films

ADVANCES IN POLYMER TECHNOLOGY, Issue 1 2009
Anand Kumar Gupta
Abstract Polyimide (PI) has been extensively investigated as matrices for blends in the search for novel materials for microelectronics and engineering application. The processing of the PI with hydroxyl-terminated polybutadiene (HTPB) offers a considerable advantage to develop a material having good mechanical and thermal stability. Taking this into account, the HTPB was blended with polyamic acid, which is precursor to PI to form PI + HTPB films. A number of properties were evaluated for PI + HTPB films with ultra low concentrations of HTPB. The films prepared with ultra low concentration (10,3,1 wt%) showed unusual synergism, which is attributed to the presence of in situ generated micro/nanostructures derived from HTPB. The microhardness study was used to elucidate the actual mechanical performance due to structure formation of HTPB in a nanometer regime within PI matrix. Atomic force microscopy analysis confirmed the dispersion of HTPB at nano regime within PI matrix. The enhanced thermal stability as determined by thermogravimetric analyzer and Fourier transform infrared spectrometry was attributed to the presence of micro/nanoparticle of HTPB within the PI matrix. The water absorption isotherms were measured and their abnormal behavior was correlated with micro-/nano-sized particles in the PI/HTPB film. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:48,59, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20144 [source]

Synthesis, cure kinetics, and thermal properties of the Bis(3-allyl-2-cyanatophenyl)sulphoxide/BMI blends

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
G. Anuradha
Abstract A novel allyl functionalized dicyanate ester resin bearing sulfoxide linkage was synthesized. The monomer was characterized by Fourier Transform Infrared (FT-IR) Spectroscopy, 1H-, and 13C Nuclear Magnetic Resonance (NMR) spectroscopy and elemental analysis. The monomer was blended with bismaleimide (BMI) at various ratios in the absence of catalyst. The cure kinetics of one of the blends was studied using differential scanning calorimetry [nonisothermal] and the kinetic parameters like activation energy (E), pre-exponential factor (A), and the order of the reaction (n) were calculated by Coats-Redfern method and compared with those calculated using the experimental Borchardt-Daniels method. The thermal stability of the cured dicyanate, BMI, and the blends was studied using thermogravimetric analyzer. The initial weight loss temperature of dicyanate ester is above 380°C with char yield of about 54% at 800°C. Thermal degradation of BMI starts above 463°C with the char yield of about 68%. Inclusion of BMI in cyanate ester increases the thermal stability from 419 to 441°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Oxidation Kinetics and Mechanisms of Hot-Pressed TiB2,MoSi2 Composites

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2008
Golla Brahma Raju
The densification of titanium diboride (TiB2) at lower sintering temperature requires the use of sinter-aid. However, from the high temperature application point of view, it is important to assess whether the presence of sinter-aid degrades the material properties, including the oxidation resistance. In the present work, the isothermal oxidation behavior of TiB2 - x wt% MoSi2 (x=0, 2.5, and 10) composites was carried out using thermogravimetric analyzer in order to study the effect of MoSi2 content on the oxidation kinetics of TiB2 at 1200°C for a duration of 12 h. The oxidized surface of monolithic TiB2 composed of highly textured rod-like rutile (TiO2) crystals. In contrast, the oxide scales on TiB2,MoSi2 materials consist of a thin layer of SiO2 along with TiO2. Interestingly, the analysis of the continuous measurements of the weight gain reveals parabolic rate law of oxidation for all the investigated ceramics. However, the oxidation kinetics is slower for the TiB2 -10 wt% MoSi2, probably due to the presence of SiO2 in the oxide scale. [source]

Morphologies and applied properties of PSI/PA composite particles synthesized at low temperature

POLYMER COMPOSITES, Issue 11 2008
Yumin Wu
Latex with a poly(dimethyl-siloxane) core and a poly(methylmethacrylate- butylacrylate- 2-hydroxypropyl acrylate) shell have been prepared at low temperature with potassium-persulphate (KPS), sodium formaldehyde sulfoxylate (SFS) and 2,2,-azobis [2-(2-imidazolin- 2-yl)propane] dihydrochloride (VA-044) as composite initiators by staged emulsion polymerization. Reactive surfactants were used to significantly improve the applied properties such as water adsorption ratio and thermo-properties. Transmission electron microscopy (TEM) results indicated that increasing the amount of 2-hydroxypropyl acrylate (HPA) and butylacrylate (BA) was favorable to form the core/shell particles. Particle size distribution results showed with increasing the dosages of surfactants, initiators, and seed-latex, particle size decreased. Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) results indicated the high temperature-reserved of copolymer was improved in the presence of polysiloxane. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source]

Thermal conductivity and mechanical properties of aluminum nitride filled linear low-density polyethylene composites

POLYMER ENGINEERING & SCIENCE, Issue 5 2009
Junwei Gu
To acquire polymer composites with high thermal conductivity and mechanical properties, the aluminum nitride (AlN) microparticles modified with titanate coupling reagent of isopropyltrioleictitanate (NDZ-105) were employed to blend linear low-density polyethylene (LLDPE) via powder mixing method. Thermal conductive coefficient of the AlN/LLDPE composites was measured using hot disk thermal analyzer, and the thermal stability characteristics of AlN/LLDPE composites were mainly investigated via thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC). The results indicated that the use of AlN particles modified by NDZ-105 significantly enhanced thermal conductivity and mechanical properties of AlN/LLDPE composites. The thermal conductivity coefficient , was 1.0842 W/mk with 30% volume fraction of AlN, about three times higher than that of native LLDPE. The tensile strength of composites was maximum (17.42 MPa) with 20% mass fraction of AlN. DSC analyses results indicated that AlN had an influence on the melting temperature and the crystallinity of LLDPE. Additionally, TGA analyses showed that the thermal stability of LLDPE was significantly increased with addition of AlN. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]

Crystallization and thermal behavior of multiwalled carbon nanotube/poly(butylenes terephthalate) composites

POLYMER ENGINEERING & SCIENCE, Issue 6 2008
Defeng Wu
Multiwalled carbon nanotube/poly(butylene terephthalate) composites (PCTs) were prepared by melt mixing. The nonisothermal crystallization and thermal behavior of PCTs were respectively investigated by X-ray diffractometer, polarized optical microscope, differential scanning calorimeter, dynamic mechanical thermal analyzer, and thermogravimetric analyzer. The presence of nanotubes has two disparate effects on the crystallization of PBT: the nucleation effect promotes kinetics, while the impeding effect reduces the chain mobility and retards crystallization. The kinetics was then analyzed using Ozawa, Mo, Kissinger, Lauritzen-Hoffman, and Ziabicki model, and the results reveal that the nucleation effect is always the dominant role on the crystallization of PBT matrix. Thus the crystallizability increases with increase of nanotube loadings. In addition, the presence of nanotubes nearly has no remarkable contribution to thermal stability because nanotubes also play two disparate roles on the degradation of PBT matrix: the Lewis acid sites to facilitate decomposition and the physical hindrance to retard decomposition. Hence the nanotubes act merely as inert-like filler to thermal stability. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source]