Mahesh Baboo

Morphology, miscibility and mechanical properties of PMMA/PC blends

This study deals with some results on morphology, miscibility and mechanical properties for polymethyl methacrylate/polycarbonate (PMMA/PC) polymer blends prepared by solution casting method at different concentration between 0 and 100 wt%. Dynamic storage modulus and tan δ were measured in a temperature range from 30 to 180°C using dynamical mechanical analyzer (DMA). The value of the storage modulus was found to increase with the addition of the PC in the matrix. Transition temperature of pure PMMA and pure PC is found to be 83.8 and 150°C, respectively. The result shows that the two polymers are miscible for whole concentration of PC in PMMA. The distribution of the phases in the blends was studied through scanning electron microscopy (SEM). Also the mechanical properties like elongation at break and fracture energy of the PMMA/PC blends increase with the increase in concentration of PC in PMMA.

The Structure and Thermomechanical Properties of Blends of Trans-polyisoprene with Cis-polyisoprene

The present work reports the structural and thermomechanical properties of cis- and trans-polyisoprene blends. These blends have been prepared using the solution casting method. The effect of blending on thermomechanical properties such as glass transition temperature, damping and storage modulus and mechanical properties such as toughness, elastic modulus, tensile strength and elongation of present blends has been studied. Besides these, the effect of blending on structure has also been studied. It was observed that elastic moduli, tensile strength and toughness of the TPI/CPI blends decreases with increased CPI percentage. The study also presents a relation between Tg and crystallinity.

Viscosity, glass transition and activation energy of solid cis-polyisoprene and trans-polyisoprene blends

Blends of cis-polyisoprene (CPI) and trans-polyisoprene (TPI) have been prepared by solution casting to study viscosity, glass transition temperature and activation energy for the glass transition. The viscosity of blends having different weight ratios has been obtained through a single experiment measuring storage and loss modulus using the dynamic mechanical analyser technique. The glass transition temperature is determined through the temperature at which the minimum of temperature derivative curve of viscosity falls. The activation energy of glass transition and fragility index have been obtained by employing the Vogel–Fulchar–Tammann (VFT) equation by assuming non-Arrhenius behaviour of viscosity of polymer blends. Results indicate that both glass transition and activation energy for the glass transition are influenced by composition and crosslink density of the blend.

Thickness-Dependent Mechanical Behaviour of Aluminium-Coated Polyethylene Terephthalate (PET) Films

Mechanical behaviour of aluminium-coated PET films has been investigated through Dynamic Mechanical Analyser. Aluminium is coated on PET substrate by vacuum thermal evaporation method. As thickness of aluminium coating increases from 150 nm to 350 nm, tensile strength decreases from 108.88 MPa to 99.25 MPa. This mechanical behaviour is correlated with microstructure and its evolution with the thickness of aluminium coating. Al-PET film consists of fine globular grains and average grain size increases monotonically with the film thickness. The relative contribution of the grain size to the strength of aluminium thin films is in good agreement with Hall-Patch equation.

Dynamic mechanical, mechanical and thermal analysis of CPI/NBR blends: effect of blend composition and crosslink density

Blends of cis-polyisoprene (CPI) and nitrile butadiene rubber (NBR) in different volume ratio were prepared to see the effect of composition on different properties. Structure characterization has been done through X-ray diffraction and scanning electron microscope. Scanning electron micrographs confirm homogeneous nature of all the blends. The dynamic mechanical analyzer was used to measure damping, storage modulus, glass transition temperature and mechanical properties (Young’s modulus and tensile strength) of these blends. Activation energy and fragility were determined for the non-Arrhenius (fragile) behavior of viscosity using Vogel–Fulchuer–Tammann (VFT) equation. Thermal conductivity has been analyzed through thermal constant analyzer. Results indicate that all the measured properties are dependent on blend composition and crosslink density.

Effect of 50 MeV Li+3 Ion Beam Irradiation on Thermomechanical Properties of PMMA/PC Blend Films

This paper reports the effect of the irradiation of 50 MeV Li+3 ions on the thermomechanical properties of PMMA/PC blends. The radiation has been carried out at fluences of 1010 to 1012 ions/cm2 to observe any kind of chain scissoring/crosslinking occurring in the sample. The irradiated as well as the pristine samples have been characterized using X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM) and dynamic mechanical analyzer (DMA) to study the induced changes in the structural, morphological and mechanical properties in blend films. The XRD results show an increase in the degree of crystallinity upon ion irradiation at low fluences (≤1011 ions/cm2) and a decrease in crystallinity at high fluences (>1011 ions/cm2), while the FTIR spectra show no appreciable change after irradiation. The mechanical characterization reveals that radiation significantly modifies the mechanical properties and the glass transition temperature of these polymeric blends.

Thermo-mechanical properties and thermal conductivity of CdS-trans-polyisoprene, polymer nanocomposite

Abstract This paper focuses on the comparative evaluation of the glass transition temperature (Tg), storage modulus and thermal conductivity of trans-polyisoprene (TPI) and CdS-TPI nanocomposite. The CdS nanoparticles synthesized by chemical route are dispersed into TPI using ultrasonic vibrations. Particle size of nanocrystals is obtained from X-ray diffraction and found to be 1.84 nm. Thermo-mechanical properties (Tg and storage modulus) are measured by dynamic mechanical analyzer (DMA), while thermal conductivity is a measured using the transient plane source (TPS) technique. It is observed that glass transition temperature and thermal conductivity are higher while storage modulus and mechanical properties are lower for CdS-TPI nanocomposites than for pure TPI. This has been explained on the basis of structural changes occurring due to introduction of CdS as filler into the TPI.

Effect of Temperature on Thermal Transport and Mechanical Properties of Trans‐polyisoprene

Thick and thin films of trans‐polyisoprene (TPI) have been prepared using solution casting method by dissolving TPI in toluene. Thick films of TPI have been used to determine thermal transport properties at different temperatures through Thermal Constant Analyzer (TCA). The results show that thermal conductivity, thermal diffusivity and volumetric heat capacity increase with respect to temperature. Thin films of TPI on the other hand have been utilized for the measurement of mechanical properties such as Young’s modulus, tensile strength and toughness. The effect of temperature on the mechanical properties of thin films of TPI has been investigated using Dynamic Mechanical analyzer (DMA) and it was found that the mechanical properties decrease with increasing temperature. Above said behavior of the thermal transport and mechanical properties as a function of temperatures is attributed to the increase in free volume of molecules in chains with temperature.

Thermo‐Mechanical Study of Chalcogenide (CdS, ZnS) Coated Polyethylene Terephthalate (PET) Films

Chalcogenide materials such as CdS/ZnS have been coated on polyethylene terephthalate (PET) films using vacuum thermal evaporation method. Commercial PET film of thickness 20 μm has been used as flexible substrate. The structure of PET and coated materials (CdS, ZnS) has been determined using X‐ray diffraction pattern (XRD). Thermo‐mechanical study of these films has been carried out using Dynamic Mechanical Analyser (DMA). The glass transition temperature (Tg) of CdS‐PET and ZnS‐PET films have been found to be 118.3°C and 117.4°C respectively whereas Tg of commercial PET film is 89.7°C. The stress‐strain curves of CdS (or ZnS)‐PET films at room temperature explain the mechanical response of these films under the applied load.

Compositional effect on thermo-mechanical, thermal and tensile properties of cis-polyisoprene and chloroprene rubber blends

ABSTRACT Blends of cis-polyisoprene (CPI) and chloroprene rubber (CR) have been prepared in different blend compositions by solution casting. Structural characterization of these blends has been done using X-ray diffraction and scanning electron microscopy. The experimental values of thermo-mechanical properties, mechanical properties and thermal conductivity of so-prepared blends determined using dynamic mechanical analyzer and thermal constant analyzer have been presented. Crosslink density has been determined using different models. Experimental results from thermo-mechanical properties show that all the blends are immiscible. Tensile strength, toughness, Youngs modulus and thermal conductivity of these blends were found to be higher than that of pure CPI and pure CR. However, mechanical properties of 25/75(V/V) of CPI/CR blend and thermal conductivity of 75/25(V/V) of CPI/CR blend have been found to be highest.