The study aims for a comparative study of butyl rubber (IIR) and bromobutyl rubber (BIIR) based on spectroscopic, dielectric and thermal characterization. Using FTIR, complete vibrational analysis of butyl rubber and bromobutyl rubber are made available which confirms their chemical structure and the functional groups present in them. The effect of microwave frequency, namely 10 GHz and 26 GHz ...

In this work, we investigate the piezoresistive response of epoxy-graphite composites. A resistive thick-film Wheatstone bridge is deposited by screen-printing onto a beam, a weight is then applied on the tip of the beam and the resulting electrical signal response is recorded, allowing the calculation of the gauge factor. The characterization was made at room temperature, 65°C and 100°C for di...

Curing cycle has a strong impact on the thermal and mechanical behavior of thermosetting polymers. The extent of cross-linking which is a strong function of curing temperature and time is directly linked to the glass transition temperature (Tg) of the thermosetting polymer. This transition temperature speaks about the transformation of the polymer from glassy state to rubbery state, hence decid...

A calorimetric method of obtaining directly the fragility of liquids from the fictive temperatures of variably quenched glasses, is outlined. "Steepness indexes" m, have been determined for a group of molecular liquids of diverse character, and vary in the range 50-150. The values obtained mostly agree well with those from earlier studies using dielectric relaxation, heat capacity spectroscopy,...

Molecular dynamics (MD) simulation provides a unique window into the dynamics of amorphous silicates of geochemical importance. Of special interest are theories of the glass transition and viscosity when an equilibrium liquid passes through the metastable supercooled liquid state to become a nonequilibrium glass. Viscosity increases enormously in a small temperature range around the glass trans...

The pressure dependence of the glass-transition temperature, Tg(P), of the ionic glass-former 2Ca(NO3)2 x 3KNO3, CKN, has been obtained by molecular dynamics (MD) simulations The liquid-glass difference of thermal expansivity, deltaalpha, heat capacity, deltaCp, and isothermal compressibility, deltak, have been calculated as a function of pressure. It has been found that the Ehrenfest relation ...

Fenofibrate is mainly used to reduce cholesterol level in patients at risk of cardiovascular disease. Thermal transition study with the help of differential scanning calorimetry (DSC) shows that the aforesaid active pharmaceutical ingredient (API) is a good glass former. Based on our DSC study, the molecular dynamics of this API has been carried out by broadband dielectric spectroscopy (BDS) co...

Maleic anhydride (MAN) copolymers with methyl methacrylate(MMA), ethyl methacrylate(EMA), methyl acrylate(MA), ethyl acrylate (EA) and buthyl acrylate (BA) ( in a 1:1 mole ratio) were synthesized by free radical polymerizations method under vacuum -azobis(isobutironitrile)(AIBN) as an initiator of reaction at 701C. The copolymer compositions were determined using related 1H NMR spectra techni...

This manuscript studied the effect of counterion on the glass transition and recrystallization behavior of amorphous salts of prazosin. Three amorphous salts of prazosin, namely, prazosin hydrochloride, prazosin mesylate and prazosin tosylate were prepared by spray drying, and characterized by optical-polarized microscopy, differential scanning calorimetry and powder X-ray diffraction. Modulate...

A solid—amorphous or crystalline—is defined by a finite shear modulus while a fluid lacks such. We thus experimentally investigate the elastic properties of a colloidal glass former near the glass transition: Spectroscopy of vibrational excitations yields the dispersion relations of longitudinal and transverse phonons in the glassy state. From the long-wavelength limit of the dispersion relatio...