Dynamic Mechanical Analysis Studies Research Articles

Thermal properties of single walled carbon nanotubes composites of polyamide 6/poly(methyl methacrylate) blend system

The nanocomposites of polyamide 6 (PA6)/poly(methyl methacrylate) (PMMA)/non-functionalized and functionalized [carboxylic acid (COOH) and hydroxyl (OH)] single wall carbon nanotubes (SWCNTs) were prepared in mass ratios of 79.5/19.5/1, 49.5/49.5/1, and 19.5/79.5/1 by melt–mixing method at 230 °C. The PA6/PMMA blends with mass ratios of 80/20, 50/50, and 20/80 served as references. The Fourier transform infrared analyses of nanocomposites showed the formation of hydrogen bond interactions among PA6, PMMA, and OH and COOH functional groups of SWCNTs. The nanocomposites and blends had higher thermal stability with respect to the PMMA. The differential scanning calorimeter (DSC) curves showed that the nanocomposites and blends exhibited two Tg values at around 51 and 126 °C for PA6 and PMMA, respectively. About 20 °C early crystallization was observed in nanocomposites compared to the blends. The dynamic mechanical analysis (DMA) results suggested that among all the compositions of blends and nanocomposites, storage modulus (E′) was higher for PMMA-rich blends and nanocomposites. At 25 °C, the E′ values were higher for blends and nanocomposites compared to the neat PA6. The tan δ curves indicated that the more heterogeneity of the hybrid nature resulted in PA6/PMMA/SWCNTs-OH or SWCNTs-COOH with 79.5/19.5/1 mass ratio nanocomposites compared to the PA6/PMMA with 80/20 mass ratio blend. The higher Tg values of PA6 and PMMA were observed in DMA studies compared to the DSC studies for PA6 and PMMA as neat and in blends and nanocomposites. The significant improvements in crystallization of nanocomposites were considered resulting from achieving better compatibility among the polymer components and carbon nanotubes.

Crystallization behavior, thermal and mechanical properties of PHBV/graphene nanosheet composites

Biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/graphene nanosheet (GNS) composites were prepared via a solution-casting method at low GNS loadings in this work. Transmission electron microscopy revealed that a fine dispersion of GNSs was achieved in the PHBV matrix. The thermal properties of the nanocomposites were investigated by thermogravimetric analysis, and the results showed that the thermal stability of PHBV was significantly improved with a very low loading of GNSs. Nonisothermal melts crystallization behavior, spherulitic morphology and crystal structure of neat PHBV and the PHBV/GNSs nanocomposites were investigated, and the experimental results indicated that crystallization behavior of PHBV was enhanced by the presence of GNSs due to the heterogeneous nucleation effect; however, the two-dimensional (2D) GNSs might restrict the mobility of the PHBV chains in the process of crystal growing. Dynamic mechanical analysis studies showed that the storage modulus of the PHBV/GNSs nanocomposites was greatly improved.

Optimisation of oil palm ash as reinforcement in natural rubber vulcanisation: A comparison between silica and carbon black fillers

Oil palm ash (OPA) as filler was compounded with natural rubber (NR) using conventional laboratory-sized two roll mills. For comparison purposes, two commercial fillers (i.e. silica and carbon black) were also studied. The optimum loading of each type of filler was investigated and compared in terms of, curing characteristics, tensile properties, rubber-filler interaction and dynamic mechanical analysis. Results showed that scorch time and cure time of carbon black filled vulcanizates was the lowest compared to OPA and silica-filled NR vulcanizates. However, the incorporation of OPA offers the highest cure rate index. From a reinforcement perspective, the carbon black-filled vulcanizates had the highest tensile strength (26 MPa), followed by OPA (25 MPa) and silica (23 MPa). It is worth noting that the incorporation of OPA increased the elongation at break by 7.4% whereas silica and carbon black reduced the elongation at break of the NR compound. Further evidence of interaction was supported by the measurement of rubber-filler interaction, dynamic mechanical analysis and morphological studies.

Novel high-performance nickel/poly(ether ether ketone) nanocomposites

The present investigation deals with the preparation and characterization of nanocomposites of poly(ether ether ketone) (PEEK) containing nanosized nickel filler up to 3 wt% loading. Characterization of the developed nanocomposites has been carried out by various advanced analytical techniques. Thermogravimetric analysis study depicts that the prepared nanocomposites exhibit enhanced thermal stability. Dynamic mechanical analysis (DMA) technique has been utilized to investigate the viscoelastic deformation of nanocomposites. From DMA studies, it has been demonstrated that with the increase in nano-nickel content, the stiffness of nanocomposites decreases and a very minute change in glass transition temperature ( Tg) has been noticed. The resulting nanocomposites show the optimum improvement in Young’s modulus, tensile strength, flexural strength and flexural modulus. Scanning electron microscopy study reveals that he dispersion of nano-nickel particulates is uniform throughout the PEEK matrix.

Rheological and thermomechanical behaviour of polylactide/hexadecyl trimethyl ammonium–modified layered silicate nanocomposites

This work is focused on the modification of montmorillonite by hexadecyl trimethyl ammonium bromide (HDTMA) as a surfactant by cation exchange reaction. HDTMA-modified layered silicate (HDTMA-MLS) was compounded with polylactide (PLA) by melt extrusion technique for making nanocomposites. These nanocomposites were subjected to morphological, rheological, thermal and mechanical analyses. Variations in mechanical properties, plasticity and thermal stability with the addition of modified nanoclays in PLA were investigated. The presence of HDTMA in clay minerals was confirmed by Fourier-transform infrared (FTIR) analysis that shows two absorption bands at 2927 cm−1 and 2860 cm−1 that corresponds to the asymmetric and symmetric stretching vibrations of C–CH2 of alkyl chain, respectively, and the band at about 1470 cm−1 was assigned to the vibration of trimethyl ammonium quaternary group C–N(CH3)3. Melt rheology of virgin PLA and nanocomposites performed by small amplitude oscillation shear measurement. Incorporation of HDTMA-MLS (1–7 wt%) into PLA matrix yields significant improvements in the elastic modulus ( G′) of nanocomposites due to intercalation at high temperature. X-Ray diffraction (XRD) and transmission electron microscopy determined that PLA/HDTMA-MLS nanocomposites were intercalated. Nanocomposite prepared using 5 wt% HDTMA-MLS exhibited optimum mechanical performance with an increase in the tensile and flexural modulus and impact strength as compared to virgin PLA, which confirms intercalation morphology. Dynamic mechanical analysis study revealed an increase in the storage modulus ( G′) confirming a strong interaction between the modified clays and PLA. Differential scanning calorimetry and thermogravimetric analysis showed improved thermal properties. Heat deflection temperature of the matrix also increases in the presence of nanoclays.

Influence of hydroxypropyl cellulose on molecular relaxations of epoxy-amine networks

A dynamic mechanical analysis (DMTA) study was conducted on epoxy-amine networks crosslinked in the presence of low contents of hydroxypropyl cellulose (HPC). The epoxy resin chosen was diglycidylether of bisphenol-A (DGEBA) and the crosslinker was 4,4'-diaminodiphenylmethane (DDM). In the glassy region, primary (α) and secondary (β, γ) relaxations originating from the epoxy and HPC components were well detected. Two primary relaxations of neat epoxy and epoxy/HPC systems, referred to as αepoxy and α'epoxy, could be detected, showing a particular glassy behavior for the systems studied in comparison with systems cured in bulk. The main relaxation temperature Tα (at the peak of αepoxy relaxation) of the epoxy systems increased slightly with the addition of HPC. The activation energy for this transition (Tα) of the epoxy-amine networks was determined both from tan δ and the peak temperatures for the loss modulus measured at various frequencies. The activation energy of the αepoxy relaxation determined from the loss modulus was more reliable than that based on tan δ. The addition of HPC lowered the activation energy of this αepoxy relaxation.

Dynamic Mechanical, DSC, and Electrical Investigations on Nano Al2O3 Filled PVA:NH4SCN:DMSO Polymer Composite Dried Gel Electrolytes

This paper reports the dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and ionic conductivity studies on nanosized Al2O3(aluminium oxide) filled PVA:NH4SCN:DMSO polymer composite dried gel electrolytes prepared by the wet chemistry route. Better mechanical stability and thermal behavior are noticed in the composite system. Multiple relaxation peaks seen in tangent loss measurements (in DMA studies) have been suitably correlated. Enhancement in ionic conductivity has been noticed with an optimum value of 4.02 × 10−3 Scm−1 for 4 wt% nano Al2O3 filled composite electrolytes. Temperature dependence of ionic conductivity shows a combination of Arrhenius and VTF (Vogel-Tamman-Fulcher) behavior.

The adhesion properties of natural rubber pressure-sensitive adhesives using palm kernel oil-based alkyd resins as a tackifier

Alkyd resins, synthesized from palm kernel oil (PKO), were investigated as the tackifiers in the formulation of natural rubber (NR) based pressure-sensitive adhesives (PSA). PKO alkyd resins were prepared via a step-wise polymerization process where the esterification was completed with the presence of xylene (solvent cook). Two alkyds, namely Alk-26 and Alk-41, with respective short and medium oil lengths of 26 and 41, were synthesized in xylene. NR was isolated from latex, dried, milled and dissolved in xylene. The alkyd solutions were then blended with NR solution in various ratios. The blend solutions were coated onto strips of corona-treated polypropylene film and the solvent removed by evaporation. The peel and shear strengths of the PSA tapes were measured. Circular samples of the blends were cast onto release paper and tested for viscoelastic properties using dynamic mechanical analysis (DMA). It was found that Alk-26 increased the shear strength of NR while Alk-41 improved the peel strength of NR significantly. These adhesion properties were comparable to some of the commercial PSA tapes available on the market. DMA study revealed that both Alk-26 and Alk-41 were immiscible with NR and there was neither cross-linking nor entanglement present in the blends.

Preparation, structure and properties of dynamically vulcanized polypropylene/acrylonitrile butadiene rubber/zinc dimethacrylate ternary blend composites containing maleic anhydride grafted polypropylene

This work demonstrated an approach to compatibilization between polypropylene (PP) and acrylonitrile butadiene rubber (NBR) by using maleic anhydride grafted polypropylene (MA-g-PP) as a compatibilizer in the presence of zinc dimethacrylate (ZDMA). It was observed that ZDMA increased the interfacial bonding between NBR and PP matrix. Incorporation of MA-g-PP further increased the mechanical properties of the resultant blends. The morphology analysis, dynamic mechanical analysis (DMA) and crystallization behavior study indicated that incorporation of MA-g-PP would change the polarity of the PP phase, facilitating more ZDMA diffusing from NBR into the PP phase during melt mixing. As a result, the possible creation resulted from polymerization of ZDMA combined with MA-g-PP increased the interface adhesion and compatibility between PP and NBR phases, which contributed to the considerable improvement in mechanical properties of the resultant blends. Moreover, we found that MA-g-PP did not influence the size of the crosslinked NBR phase, but significantly improved the viscosity of the resultant materials.

Lightly branched comb polyesters: Application in fast drying solvent-borne coating formulations

Novel oxazoline-based comb-polymers possessing linoleyl or oleic side chains have been synthesized and used to produce low viscosity coatings. Inclusion of the polymers in model paint formulations results in coatings that exhibit faster drying times than commercially available alkyd resin formulations. The comb polymers were produced from diol substituted oxazoline monomers that were synthesized through a scalable, solvent free protocol and purified by simple recrystallisation. Co-polymerisation of the oxazolines with adipic acid at 160°C in the bulk resulted in the targeted polyester comb type polymers. The polymers were soluble in a range of organic solvents and compatible with commercial alkyd resins. Model paint formulations containing up to 40wt% of the linoleyl-based comb polymers exhibited a dramatic reduction in viscosity (from 35 to 13 Poise at 25°C) with increasing quantities of polymer added. Dynamic mechanical analysis (DMA) studies revealed that the drying rate of the model paint formulations containing the comb polymers was enhanced when compared with that of commercial alkyd resins.

Modification of CNT and its effect on thermo mechanical, morphological as well as rheological properties of Polyether Imide (PEI)/Liquid Crystalline Polymer (LCP) blend system

This work analysed the effect of physical and chemical interactions between the modified mutiwalled carbon nanotubes (MWCNTs) and the Polyetherimide/Liquid crystalline polymer (PEI/LCP) blend matrix, on the dispersion of MWCNTs and deformation of LCP particles. Silicon Carbide (SiC) and TiO2 coated MWCNTs were prepared from polycarbosilane and titanium (IV) n- butoxide precursors, respectively, by sol–gel process to improve their dispersion in the polymer matrix. Formation of both was confirmed by X-Ray diffraction (XRD), Transmission Electron Microscope (TEM) and X-Ray photoelectron Spectroscopy (XPS) studies. Polyetherimide (PEI)/liquid crystalline polymer (LCP) blends with unmodified and modified MWCNTs were prepared by melt blending. TEM and Field Electron Scanning Electron microscope (FESEM) studies revealed better dispersion of modified MWCNT in the polymer matrix than the unmodified one. Rheological analysis of hybrid composite systems containing modified and unmodified MWCNT revealed that nano composite containing TiO2 coated MWCNT has the lowest viscosity and this is due to fibrillation of LCP. Superior thermal stability of modified MWCNT added composites was confirmed from thermo-gravimetric analysis (TGA). Dynamic mechanical thermal analysis (DMTA) and Differential Scanning Calorimetry (DSC) studies showed the variation in glass transition temperature (Tg) of the composites in presence of pure and modified MWCNT. Mechanical properties of nanocomposites with TiO2 coated MWCNTs were found to be higher than that of pure MWCNTs added nanocomposite.

Responsive organogels formed by supramolecular self assembly of PEG-block-allyl-functionalized racemic polypeptides into β-sheet-driven polymeric ribbons.

A chemically reactive hybrid diblock polypeptide gelator poly(ethylene glycol)-block-poly(dl-allylglycine) (PEG-b-PDLAG) is an exceptional material, due to the characteristics of thermo-reversible organogel formation driven by the combination of a hydrophilic polymer chain linked to a racemic oligomeric homopeptide segment in a range of organic solvents. One-dimensional stacking of the block copolymers is demonstrated by ATR-FTIR spectroscopy, wide-angle X-ray scattering to be driven by the supramolecular assembly of β-sheets in peptide blocks to afford well-defined fiber-like structures, resulting in gelation. These supramolecular interactions are sufficiently strong to achieve ultra low critical gelation concentrations (ca. 0.1 wt%) in N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and methanol. The critical gel transition temperature was directly proportional to the polymer concentration, so that at low concentrations, thermoreversibility of gelation was observed. Dynamic mechanical analysis studies were employed to determine the organogel mechanical properties, having storage moduli of ca. 15.1 kPa at room temperature.

Hybrid polybenzoxazine with tunable properties

The difunctional urushiol-based benzoxazine (U-da) was synthesized by utilizing urushiol, 4,4′-diaminodiphenyl methane (DDM) and formaldehyde. The 3,3′-phenylmethanebis(3,4-dihydro-2H-1,3-benzoxazine) (P-da) was prepared by the similar procedure with DDM, phenol and formaldehyde. The U-da and P-da were cured into hybrid polybenzoxazine with different U-da fractions, where the alkyl chains in urushiol can improve the ductility of the polybenzoxazines. Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) studies demonstrate that the thermally activated ring-opening polymerization can happen at a relatively low temperature (∼180 °C) without addition of catalyst. The hybrid polybenzoxazines were measured by thermal gravimetric analysis (TGA). It shows the temperatures corresponding to the 5% and 10% weight loss are slightly affected by the U-da content whereas the residual weight at 800 °C increases with P-da content. Dynamic mechanical analysis (DMA) studies indicate that the hybrid polybenzoxazine with U-da content of 50 wt% has a relatively high elongation (10%) and stress (101 MPa) at break. The properties of the hybrid polybenzoxazine can be tuned by the composition.

Evaluation of Fishmeal as Starting Material for Producing Biodegradable Protein-Based Thermoplastic Polymers

Evaluate low value marine waste material from farmed Atlantic salmon (Salmo salar) as starting material for the production of low cost, biodegradable protein-based thermoplastic polymers. Dynamic mechanical analysis, compression moulding, gel permeation chromatography, scanning electron microscopy and amino acid distribution analysis. Through a series of dynamic mechanical analysis studies it was shown that fishmeal can be plasticized with hydrophilic plasticizers to yield a material that can be successfully compression moulded into consolidated polymers at temperatures above the glass transition temperatures of the mixtures. Addition of SDS and urea further increased the processability of the fishmeal and homogenous polymers were produced. The mechanical properties of the polymers were poor and they were generally too brittle to allow extensive mechanical testing. Scanning electron microscopy revealed a sheet-like sub-structure within the polymer network which explained the poor mechanical properties. Gel permeation chromatography and amino acid distribution analysis of the fishmeal indicated that the proteins in the fishmeal are of low molecular weight with a high content of collagen. The fishmeal was also evaluated as part of polymeric blends with polyethylene, biodegradable polybutylene succinate and bovine bloodmeal. It was possible to generate consolidated fish waste based polymeric materials. Fishmeal did not perform as well as bovine bloodmeal as a thermoplastic biopolymer mainly due to its low protein content and low molecular mass.

Effect of TiO2 nanoparticles on basalt/polysiloxane composites: mechanical and thermal characterization

In the present investigation, a novel technique has been developed to fabricate composite materials containing TiO2 nanoparticles, polysiloxane resin, and basalt fabric. A high-intensity ultrasonic probe was used to obtain a homogenous molecular mixture of TiO2 nanoparticles and polysiloxane resin, thus the nanoparticles were infused into the resin through sonic cavitation. The loading effect of TiO2 nanoparticles on the thermal and mechanical properties of basalt fabric reinforced polysiloxane composite materials has been investigated. Composite samples were prepared, each using two layers of basalt fabric with TiO2 nanoparticles loading from 0.5, 1, 1.5, 2, 2.5, and 3% by weight. Size distribution of nanoparticles was observed by particle size analyzer and the prepared fabric nanocomposites were characterized by scanning electron microscopy, dynamic mechanical analysis (DMA), thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC). Tensile testing was performed as per American standard for testing of materials (ASTM) standards. The dependence of dynamic mechanical parameters E′, E′′, tan (delta), T g, and heat distortion temperature (HDT) are associated with the filler content and can be controlled by the curing conditions. Tensile results show that 1.5 wt.% loading of TiO2 nanoparticles in the nanocomposites resulted in highest improvement in tensile modulus compared to the neat system. DMA studies also revealed that 1.5 wt.% doped system exhibits highest storage modulus as compared to the neat and other loading percentages. DSC and TGA studies show that T g and HDT of the composite increases with the increase in wt.% of nanofillers in the composite. Based on these results, it is clear that miscibility of nanoparticles in the resin is of prime importance with regard to performance.

On the development and characterisation of crosslinked sodium alginate/gelatine hydrogels

Sodium alginate (SA) and gelatine (G) based hydrogels with various SA/G ratios, crosslinked with calcium ions (Ca2+) and glutaraldehyde (GTA), respectively, were developed. Scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and dynamic mechanical analysis (DMA) were applied to determine their physicochemical characterization. The swelling studies, conducted in phosphate-buffered saline with a pH ranging from 1 to 11 at 37°C, were utilized for an evaluation of their absorption ability. FTIR spectra of the Ca2+ crosslinked SA/G hydrogels revealed a small shift in symmetric stretching carboxyl groups, indicating an ionic binding between the Ca2+ ions and the SA. Increasing the G content in hydrogels crosslinked with GTA significantly changed the shapes of the amide I and II bands in the FTIR spectra, thus confirming the G–GTA crosslink formation. After crosslinking, a DMA study proved the enhanced viscoelastic properties and improved thermal stability of the prepared samples. The obtained data indicated that Ca2+ crosslinked hydrogels with a SA/G 50/50 ratio provide a good balance of swelling and viscoelastic properties, making them applicable as a potential nontoxic wound dressing material capable of adequately assuring a moist environment, elasticity and mechanical strength for comfortable wound healing.

Effectiveness of amine functional aniline furfuraldehyde condensate as toughening agent for epoxy resin

PurposeThe purpose of this paper is to find a new toughening agent for diglycidyl ether of bisphenol A (DGEBA) resin and to check effectiveness of this new toughening agent to obtain toughness and chemical resistance of cured epoxy.Design/methodology/approachFor this purpose, an investigation was carried out to synthesise, characterise and to study the toughening reaction of amine functional aniline furfuraldehyde condensate (AFAFFC) with DGEBA resin. AFAFFC was first synthesised from the reaction of aniline and furfuraldehyde in the acid medium (pH‐4) and characterised by FT‐IR spectroscopy, elemental analysis and concentration of primary and secondary amine analysis. Then various formulations were made by mixing DGEBA, AFAFFC and ambient temperature curing agent triethylene tetramine (TETA) in different compositions and the modified networks were evaluated to their mechanical and thermal properties. The dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) studies and thermogravimetric analysis (TGA) of toughened epoxy were also reported.FindingsThe resulting networks developed a two‐phase microstructure upon network formation and displayed significantly improved fracture toughness. The dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM) studies showed two‐phase morphology in the cured networks where AFAFFC particles were dispersed. TGA showed that the AFAFFC modified epoxy network was thermally stable up to around 311°C.Research limitations/implicationsThe toughening agent AFAFFC has been synthesised by using aniline and furfuraldehyde. By changing amine and aldehyde other toughening agents could be synthesised and efficiency of these toughening agent for epoxy resin could also be studied.Originality/valueThe method for toughening of epoxy resin (DGEBA) is novel and relevant, as the toughened products have high performance applications in protective coatings, adhesives for most substrates and matrix resins for composites.

Positive temperature coefficient to resistively characteristics of polystyrene/nickel powder/multiwall carbon nanotubes composites

AbstractPositive temperature coefficient to resistivity (PTCR) characteristics of polystyrene (PS)/Ni‐powder (40 wt%) composites in the presence of multiwall carbon nanotubes (MWCNTs) has been investigated with reference to PS/carbon black (CB) composites. The PS/CB (10 wt%) composites showed a sudden rise in resistivity (PTC trip) at ≈110°C, above the glass transition temperature (Tg) of PS (Tg ≈95°C). Interestingly, the PTC trip temperature of PS/Ni‐powder (40 wt%)/MWCNT (0.75 phr) composites appeared at ≈90°C (below Tg of PS), indicating better dimensional stability of the composites at PTC trip temperature. The PTC trip temperature of the composites below the Tg of matrix polymer (PS) has been explained in terms of higher coefficient of thermal expansion (CTE) value of PS than Ni that led to a disruption in continuous network structure of Ni even below the Tg of PS. The dielectric study of PS/Ni‐powder (40 wt%)/MWCNT (0.75 phr) composites indicated possible use of the PTC composites as dielectric material. Dynamic mechanical analysis (DMA) and thermogravimetric analysis studies revealed higher storage modulus and improved thermal stability of PS/Ni‐powder (40 wt%)/MWCNT (0.75 phr) composites than the PS/CB (10 wt%) composites. POLYM. COMPOS., 33:1977–1986, 2012. © 2012 Society of Plastics Engineers

A novel acrylamide-anatase hybrid nanocomposite

A novel hybrid-nanocomposite of polyacrylamide-TiO2 (PAM/TiO2) with nano-anatase particles was synthesized in two steps. Firstly, the surface of nano-anatase particles was modified by 3-methacryloxy-propyl-trimethoxysilane (TMSM) as coupling agent by sol–gel method. Secondly, the surface modified nano-anatase particles were grafted onto the acrylamide monomer (AM) as an organic phase by free radical polymerization. The spectral (Fourier transform Infrared spectroscopy) and thermal (TGA) methods, verified the participation of coupling agent, polymer and titanium dioxide (anatase) into the hybrid structure. The results also showed that the degradation temperatures and residual content were obviously higher in nanocomposite than those of pure polyacrylamide (PAM). Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) studies proved that the nano-anatase particles have been uniformly encapsulated inside the nanocomposite sample containing 5wt% TiO2. However, the agglomeration of nano-particles in the nanocomposite with 20wt% of TiO2 was detected by atomic force microscopy (AFM) and dynamic mechanical thermal analysis (DMTA) studies. Thermo-mechanical properties of acrylamide homopolymer (PAM) and their nanocomposites were investigated by DMTA. The shifts in storage modulus and tanδ peaks were attributed to morphological changes in the nanocomposites with increasing the amount of inorganic nano-particles and their distribution in polymer matrix. Flocculation behavior of PAM and PAM/TiO2 in two different level of titanates (i.e. 5 and 20wt% TiO2) for 0.25wt% nano-clay suspension was evaluated using batch method. The adsorption results showed that PAM/TiO2 have ability for interaction with clay particles by means of adsorption through electrostatic interaction, Vander Waals forces and hydrogen bonding. However, it was found that the flocculation efficiency of the pure polymer (PAM) and the hybrid-nanocomposite (5wt% TiO2) is much better than that of its high concentration (20wt% TiO2) in the hybrid. This flocculation behavior can be attributed to uniform distribution of nano-particles and agglomeration possibility in the case of low and high concentration level of titanate in hybrid nanocomposite, respectively.

Dynamic mechanical analysis and dielectric studies of agro-waste rice husk/polypropylene composites with cenosphere

Effect of cenosphere addition, on agro-waste rice husk/polypropylene composites is studied. Rice husk reinforced polypropylene composites having 20% rice husk with and without cenosphere is developed. Treated and untreated cenospheres with different concentration were loaded with chopped rice husk in polypropylene. The dielectric behaviour of rice husk-filled polypropylene was studied by adding cenosphere (2, 4, 6 and 8 phr), respectively, in concentrations. From dynamic mechanical analysis, analysis is clear that the loss factor of composites decreased and the storage modulus improved in the presence of cenosphere in polypropylene/rice husk, which indicated much better interfacial adhesion between the polypropylene matrix and rice husk. Insulating materials are used in electrical power circuits to prevent leakage of current. This study investigates the possibility of using agro-waste rice husk, as electrical insulators. Accordingly, electrical insulative properties: dielectric constant, dissipation factor and ac conductivity σac of these waste materials were determined. In case of dielectric constant of filled polymers, interface interaction is the most important parameter which influences the dielectric behaviour of matrix and will depend on type of fillers, concentration of filler and the chemical bonding between filler and matrix.