Completely biodegradable composites of poly(propylene carbonate) and short,lignocellulose fiber Hildegardia populifolia

The composites of biodegradable poly(propylene carbonate) (PPC) reinforced with short Hildegardia populifolia natural fiber were prepared by melt mixing followed by compression molding. The mechanical properties, thermal properties, and morphologies of the composites were studied via static and dynamic mechanical measurements, thermogravimetric analysis, and scanning electron microscopy (SEM) techniques, respectively. Static tensile tests showed that the stiffness and tensile strength of the composites increased with an increasing fiber content. However, the elongation at break and the energy to break decreased dramatically with the addition of short fiber. The relationship between the experimental results and the compatibility or interaction between the PPC matrix and fiber was correlated. SEM observations indicated good interfacial contact between the short fiber and PPC matrix. Thermogravimetric analysis revealed that the introduction of short Hildegardia populifolia fiber led to a slightly improved thermooxidative stability of PPC. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 666–675, 2004     

A calciferous hornblende from amphibolite of Kushalnagar,Coorg district,Mysore state

Hornblende from an amphibolite, occurring near Kushalnagar, has been studied in detail for its optical characters and chemical composition. Based on these characters, it has been identified as Pargasite with a negative optic sign. The mode of origin is also discussed.     

Preparation and properties of poly(vinyl alcohol)–vermiculite nanocomposites

A vermiculite (VMT) dispersion in water was blended with aqueous poly(vinyl alcohol) (PVA). The properties of the PVA–VMT nanocomposites greatly depended on the preparation procedure because of the chemical reactions and physical interactions involved. The samples were prepared in two steps to investigate the properties of the PVA–VMT nanocomposites. The VMT was first pretreated and delaminated with hydrochloric acid. The delaminated VMT was then added to the PVA solution with various mixing times. The structure and properties of the films were investigated. From X‐ray diffraction and transmission electron microscopy, the VMT layers were found to be well dispersed individually in the PVA–VMT blends. The effect of the VMT content on the thermal behavior of the PVA–VMT blends was also studied with differential scanning calorimetry. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 749–755, 2003     

Electronegativities in the calculation of diatomic molecular parameters (Hydrides of some transition elements)

The force constants for diatomic molecules and isolated bonds may be expressed by using equalized electro-negativities, bond orders, bond strengths and interatomicdistances. We have studied Mn¹H, Mn²H, Co²H, Ni¹H, Ni²H, Cu¹H, Cu²H, Ag¹H, and Ag²H and have determined the proportionality constant d, as well as the Lennard-Jones parameters a and b, for the potential energy functions used by Szöke and calculated the anharmonicity ω_eξ_e and the rotational-vibrational coupling constant α_e. The relation between electronegativity and ionization potential has been verified and the variations of molecular parameters with atomic number Z have been studied.     

Absorption spectrum of octahedral CoCl4(H2O)2 units in [(CH3)3NH]CoCl3·2H2O single crystal

The optical absorption spectrum of the octahedral moiety CoCl₄(H₂O)₂ in single crystal [(CH₃)₃NH]CoCl₃·2H₂O has been studied at room and liquidair temperatures. The observed ambient bands at 6800, 16,300, and 19,000 cm^–1 have been assigned, respectively, to the transitions⁴ T ₁(F) ⁴ T ₂(F),⁴ A ₂(F), and⁴ T ₁ (P). The crystal field parameters evaluated areD _q =B=850 cm^–1, andC=4.63B. At liquid-air temperatures the⁴ T ₁(P) band is seen to split into the expected four components ₇, ₈, ₈, and ₆, due to spin-orbit coupling, and the coupling coefficient was computed to be 525 cm^–1.     

Development and analysis of cellulose nanocomposite films with in situ generated silver nanoparticles using tamarind nut powder as a reducing agent

Cellulose/Tamarind nut powder (TNP)/Silver nanoparticles (AgNPs) nanocomposites were prepared by in situ generation of AgNPs using regeneration method, followed by solution casting method. In this, TNP was used as a reducing agent. These nanocomposites were characterized using FT-IR spectroscopy, XRD and SEM and studied their mechanical properties and antibacterial activity for medical and packing applications. The FT-IR spectral studies revealed the involvement of functional groups – Polyphenols, Flavonoids and –OH in the process of reducing the metal salts into metal nanoparticles. These nanocomposites showed good antibacterial activity against five bacteria. Improved mechanical properties with good antibacterial activities make these composites suitable for medical, food and packaging applications.     

Influence of Musa acuminate bio-filler on the thermal,mechanical and visco-elastic behavior of poly (propylene) carbonate biocomposites

Biocomposites were fabricated using poly(propylene) carbonate as matrix and cellulosic polysaccharide banana (Musa acuminate) peel powder as filler in varying concentrations (5–25?wt.%) and were characterized for their functional properties. Microscopic analysis indicated the uniform distribution and existence of microfibrils in the filler. The thermal stability of the composites was lower than the matrix till 320?°C, beyond which it increased. The visco-elastic and mechanical behavior of the biocomposites was found to be enhanced with the addition of fillers. Thus, with better thermal, visco-elastic, and mechanical properties, the biocomposite films can be a replacement for the non-biodegradable polymers for packaging applications.     

Highly sensitive extractive spectrophotometric determination of palladium(II) in synthetic mixtures and hydrogenation catalysts using benzildithiosemicarbazone.

A simple and highly sensitive method was developed for the extractive-spectrophotometric determination of palladium with benzilidithiosemicarbazone. The metal ion formed a reddish brown complex with benzildithiosemicarbazone in a potassium chloride-hydrochloric acid buffer of pH 2.5, which was easily extractable into methyl isobutyl ketone. The 1:1 complex showed the maximum absorbance at 395 nm with a Beer's law range of 0.25-3.5 ppm. The molar absorptivity and Sandell's sensitivity were found to be 3.018 x 10(4) dm3 mol(-1) cm(-1) and 0.0035 microg cm(-2), respectively. The correlation coefficient of the Pd(II)-BDTSC complex was 0.998, which indicated an excellent linearity between the two variables. The repeatability of the method was checked by finding the relative standard deviation (RSD) (n = 10), which was 0.46%. The instability constant of the complex calculated from Edmond and Birnbaum's method was 2.41 x 10(-5), that of Asmus' method is 2.53 x 10(-5) at room temperature. The interfering effects of various cations and anions were studied. The proposed method was successfully applied to the determination of palladium(II) in synthetic mixtures and hydrogenation catalysts. The validity of the method was tested by comparing the results with those obtained using an atomic absorption spectrophotometer.     

Tensile,thermal, and antibacterial characterization of composites of cellulose/modified Pennisetum purpureum natural fibers with in situ generated copper nanoparticles

Eco-friendly all cellulose composites were developed using cellulose as matrix and nanocomposite (in situ generated copper nanoparticles modified Napier Grass Fibers (NGFs)) as fillers for the antibacterial applications. The content of the nanocomposite filler was increased from 1?wt.% to 5?wt.% in the cellulose matrix. All these composites were characterized by Scanning Electron Microscopy (SEM), Tensile, Thermo Gravimetric Analysis (TGA), and antibacterial tests. SEM-EDX analysis revealed the in situ generation of copper nanoparticles on the surface of the films. Further, all cellulose composites showed good thermal stability. A minimum of 30% increase in char residue was observed in all cellulose nanocomposites compared to matrix. Antibacterial analysis indicated an excellent clear zone formation against both Gram Negative (Escherichia coli) and Gram Positive (Staphylococcus) bacteria. Hence, all these cellulose nanocomposite films can be considered as antibacterial packaging and dressing materials in medical field.     

Tensile properties of ligno-cellulosic fabrics coated with styrenated polyester resin

Ligno-cellulosic fabrics from the tree Hildegardia populifolia were coated with styrenated polyester resin, and their tensile strength, elastic modulus, and the percent elongation at break were determined. The effects of sodium hydroxide and a silane-coupling agent on the tensile properties of the fabric were also studied. It was observed that the tensile strength and the modulus decreased whereas the percent elongation at break increased with coating. The coupling agent improved the properties of the untreated and polyester-coated fabric, but a reverse trend was observed when the fabric was treated with sodium hydroxide. The possible reasons for this behavior are discussed.