Veena Choudhary

Adhesives and plastics based on soy protein products

Significance of eco-friendly materials based on easily renewable natural resources, and the finite nature of petrochemical resources, has necessitated the development of polymers from agricultural processing by products such as soy proteins from oil processing. Although, considerable work was done in the early part of last century on polymers based on soy protein, there was almost no activity in this field for the last fifty years. There is a need to critically analyse the available literature on soy protein based polymeric materials. Therefore, an attempt is made to review the state-of-the-art of the polymeric materials with emphasis on adhesives and plastics derived from soy protein, a renewable resource abundantly available in nature.

High permittivity polyaniline–barium titanate nanocomposites with excellent electromagnetic interference shielding response

Organic conductive polymers are at the forefront of materials science research because of their diverse applications built around their interesting and unique properties. This work reports for the first time a correlation between the structural, electrical, and electromagnetic properties of polyaniline (PANI)-tetragonal BaTiO3 (TBT) nanocomposites prepared by in-situ emulsion polymerization. XRD studies and HRTEM micrographs of these nanocomposites clearly revealed the incorporation of TBT nanoparticles in the conducting PANI matrix. EPR and XPS measurements reveal that increase in loading level of BaTiO3 results in a reduction of the doping level of PANI. The Ku-Band (12.4-18 GHz) network analysis of these composites shows exceptional microwave shielding response with absorption dominated total shielding effectiveness (SET) value of -71.5 dB (blockage of more than 99.99999% of incident radiation) which is the highest value reported in the literature. Such a high attenuation level, which critically depends on the fraction of BaTiO3 is attributed to optimized dielectric and electrical attributes. This demonstrates the possibility of using these materials in stealth technology and for making futuristic radar absorbing materials (RAMs).

Polyolefin blends: effect of EPDM rubber on crystallization, morphology and mechanical properties of polypropylene/EPDM blends. 1

Abstract Morphology, thermal behaviour and mechanical and dynamic mechanical properties of isotactic polypropylene (PP) blended with different amounts of ethylene-propylene-diene (EPDM) terpolymer were investigated. Addition of 10% (w/w) EPDM to PP resulted in an increase in spherulite size. Optical micrographs showed that the rubber was distributed both in the intra- and interspherulitic regions. The heat of fusion (ΔHf) and percentage crystallinity (wide angle X-ray scattering) of PP/EPDM blends decreased on increasing EPDM content. Scanning electron micrographs revealed a skin-core morphology in injection-moulded specimens. Melt viscosity of the PP/EPDM blends determined at 200°C using a capillary rheometer showed an increase with increasing rubber content. A non-Newtonian flow behaviour was observed in the shear rate range 40–1600 s−1. Dynamic mechanical analysis results also supported the incompatibility of PP/EPDM blends. An improvement in impact strength of PP was observed upon incorporation of EPDM elastomer.

Current Status of Unsaturated Polyester Resins

Unsaturated polyester (UP) resins are linear polycondensation products based on unsaturated and saturated acids/anhydrides and diols or oxides. These resins are generally pale yellow oligomers with...

Studies on biodegradation and release of gentamicin sulphate from interpenetrating network hydrogels based on poly(acrylic acid) and gelatin: in vitro and in vivo.

Interpenetrating network hydrogels (IPNs) based on poly(acrylic acid) and gelatin (Ge) were evaluated for in vitro and in vivo biodegradation and in vivo release of gentamicin sulphate. In vitro and in vivo degradation studies demonstrated that with the increase of acrylic acid content in the polymer, the rate of degradation decreases, and a reverse phenomenon was observed with increasing Ge content in the hydrogel. The rate of in vivo degradation was much lower than in vitro degradation. Incorporation of gentamicin sulphate in hydrogel further reduces their degradation. In vitro and in vivo drug release profile showed a burst effect, followed by controlled release. Drug concentration was measured in the local skin tissue, blood serum, kidney, liver and spleen. The local skin tissue concentration of 50% and 100% gentamicin sulphate, loaded full IPNs (i.e., Ax-1 and Ax-2), was found to be higher (20+/-2mug/g) than the minimum bactericidal concentration for Staphylococcus aureus (1.2mug/g) and Pseudomonas aeruginosa (10mug/g), respectively, for a study time of 60 days.

Flame-Retarding Plastics and Elastomers with Melamine:

Melamine has shown broad utility as a flame retardant in plastics although its commercial use to date as a flame retardant additive has been principally in coatings and flexible urethane foams. Its mode of action appears to involve endothermic sublimation and vapor-phase dissociation, but it also undergoes conversion to non-volatile products and ammonia. Combinations of melamine with other flame retardants of all types have been reported as hav ing advantageous performance. The present review covers the patent and non- patent literature with 130 references.**

Azido Polymers—Energetic Binders for Solid Rocket Propellants

2. PREPARATION OF AZIDO POLYMERS. . . . . . . . . . . . . . . . . . . . . . . 508 2.1. Polymerization of Glycidyl Azide (GA) . . . . . . . . . . . . . . . . . . . . . . 508 2.1.1. Derivatization of polyepichlorohydrin (PECH). . . . . . . . . . . 508 2.2. Direct Conversion of Epichlorohydrin to Glycidyl Azide Polymer (GAP).. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 513 2.3. Simultaneous Degradation and Azidation of PECH and Its Copolymers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514 2.4. Block Copolymers of GAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515 2.5. Polymerization of Azidomethyl Oxetanes . . . . . . . . . . . . . . . . . . . . . 515 2.6. Poly(allyl azide) (PAA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519

Effect of EPDM rubber on melt rheology, morphology and mechanical properties of polypropylene/HDPE (9010) blend. 2

Abstract Melt rheology and morphology of ternary blends of polypropylene/high density polyethylene (PP/HDPE) ( 90 10 ) and ethylene-propylene-diene (EPDM) terpolymer were investigated using an Instron capillary rheometer and Weissenberg rheogoniometer. The effect of temperature and shear rate or stress on melt viscosity was also investigated. A non-Newtonian flow behaviour was observed in all the samples in the shear rate range 40–1600 s−1, whereas at shear rates in the range 0.01–10 s−1 a Newtonian flow behaviour was observed. The morphology of the extrudates examined by scanning electron microscopy revealed the formation of agglomerates at higher concentrations of elastomer in PP/HDPE ( 90 10 ) binary blend. Impact strength of the ternary blends increased with an increase in EPDM content up to an optimum concentration (∼20% w/w) of rubber.

Interpenetrating polymer network (IPN) nanogels based on gelatin and poly(acrylic acid) by inverse miniemulsion technique: synthesis and characterization.

Novel interpenetrating polymer network (IPN) nanogels composed of poly(acrylic acid) and gelatin were synthesised by one pot inverse miniemulsion (IME) technique. This is based on the concept of nanoreactor and cross-checked from template polymerization technique. Acrylic acid (AA) monomer stabilized around the gelatin macromolecules in each droplet was polymerized using ammonium persulfate (APS) and tetramethyl ethylene diamine (TEMED) in 1:5 molar ratio and cross-linked with N,N-methylene bisacrylamide (BIS) to form semi-IPN (sIPN) nanogels, which were sequentially cross-linked using glutaraldehyde (Glu) to form IPNs. Span 20, an FDA approved surfactant was employed for the formation of homopolymer, sIPN and IPN nanogels. Formation of stable gelatin-AA droplets were observed at 2% surfactant concentration. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) studies of purified nanogels showed small, spherical IPN nanogels with an average diameter of 255 nm. In contrast, sIPN prepared using the same method gave nanogels of larger size. Fourier-transform infrared (FT-IR) spectroscopy, SEM, DLS, X-ray photoelectron spectroscopy (XPS) and zeta potential studies confirm the interpenetration of the two networks. Leaching of free PAA chains in sIPN upon dialysis against distilled water leads to porous nanogels. The non-uniform surface of IPN nanogels seen in transmission electron microscopy (TEM) images suggests the phase separation of two polymer networks. An increase of N/C ratio from 0.07 to 0.17 (from PAA gel to IPN) and O/C ratio from 0.22 to 0.37 (from gelatin gel to IPN) of the nanogels by XPS measurements showed that both polymer components at the nanogel surface are interpenetrated. These nanogels have tailoring properties in order to use them as high potential drug delivery vehicles for cancer targeting.

Polymer/Carbon Nanotube Nanocomposites

Polymer is a versatile material having many unique properties like low density, reasonable strength, flexibility, easy processibilty, etc. However, the mechanical properties of these materials are inadequate for many engineering applications. Hence, there is a continuous search towards new polymeric materials with improved properties. Initially, blending of different class of polymer was used to fabricate new materials with unique properties. However, blending lead to only marginal improvement in physical properties which were still inadequate for engineering applications. So to improve the strength and stiffness of polymer materials different kinds of organic and inorganic fillers were used. It was observed that strength and stiffness of long fibers reinforced thermosetting polymer is comparable to metals at a fraction of their weight. As a result of which these material were used in aircraft and in sport equipment. However, processing of these materials is very difficult; therefore small fiber or particle reinforced composites were developed. The common particle fillers used were silica, carbon black , metal particles etc. But significantly high filler loading was required to achieve desired mechanical property, which thus increased cost and made processibility difficult. So to achieve high mechanical properties at lower filler loading, nanofillers were used. The nanofiller reinforced polymer matrix is known as polymer nanocomposite. Polymer nanocomposites are a new class of composite materials, which is receiving significant attention both in academia and industry. As nano fillers are only a few nanometers (~10,000 times finer than a human hair) in dimension, it offers ultra-large interfacial area per volume between the nano-element and polymer matrix. As a result, the nanofiller reinforced composites exhibit enhanced toughness without sacrificing stiffness or optical clarity. It also possesses greater thermal and oxidative stability, better barrier, mechanical properties as well as unique properties like self-extinguishing behavior. Compared to different range of nanofillers, carbon nanotubes (CNTs) have emerged as the most promising nanofiller for polymer composites due to their remarkable mechanical and electrical properties (Ishikawa, 2001; Kracke & Damaschke, 2000). Currently, one of the most intriguing applications of CNTs is the CNT/polymer nanocomposites (Cai, 2000; Fiege, 1999; Gomes, 1999; Hersam, 1998; Ruiz, 1998). For the last two decades, a lot of research work has been done on evaluating the potential of CNTs as filler for polymer nanocomposites. In the present chapter, we will briefly discuss on CNTs and their properties, different fabrication methods of polymer nanocomposites and their mechanical, electrical and thermal properties.