Linear Low Density Polyethylene-Biodegradability Using Bacteria from Marine Benthic Environment and Photodegradability Using Ultraviolet Light

Various compositions of linear low density polyethylene(LLDPE) containing bio-filler(either starch or dextrin)of various particle sizes were prepared.The mechanical,thermal,FTIR,morphological(SEM),water absorption and melt flow(MFI) studies were carried out.Biodegradability of the compositions were determined using a shake culture flask containing amylase producing bacteria(vibrios),which were isolated from marine benthic environment and by soil burial test. The effect of low quantities of metal oxides and metal stearate as pro-oxidants in LLDPE and in the LLDPE-biofiller compositions was established by exposing the samples to ultraviolet light.The combination of bio-filler and a pro-oxidant improves the degradation of linear low density polyethylene.The maleation of LLDPE improves the compatibility of the c blend components and thepro-oxidants enhance the photodegradability of the compatibilised blends.The responsibility studies on the partially biodegradable LLDPE containing bio-fillers and pro-oxidants suggest that the blends could be repeatedly reprocessed without deterioration in mechanical properties.

Poverty, Inequality and Natural Resources Degradation

The present study is an attempt to understand the link between natural resource degradation and poverty among people dependent on these resources. This is done by examining the impact of depletion of marine resources on the livelihood and socio-economic condition of the small-scale marine fishery community in South Kerala. In Kerala, nearly ten lakh fisherfolk depend on the marine fishery resources for their livelihood. The overall level of education of the small-scale fishing community is lower than that of the State’s rural population. Almost all the households surveyed, is one way or other, depend on fishery resources for livelihood. Low levels percapita income and high levels of inequality imply the existence of a large proportion of poor people in the community who are vulnerable to external shocks. The study reveals that poverty was comparatively higher among households with no fishing assets, with only one earner, with more than two children, and depending entirely on pensions/remittances. The study has not provided any evidence to show that poverty in the community is the result of depletion of marine resources.

Vacuum-ultraviolet photochemically initiated modification of polystyrene surfaces: morphological changes and mechanistic investigations

Vacuum-ultraviolet (VUV) irradiation (kexc: 172 ± 12 nm) of polystyrene films in the presence of oxygen produced not only oxidatively functionalized surfaces, but generated also morphological changes. Whereas OH- and C=O-functionalized surfaces might be used for e.g. secondary functionalization, enhanced aggregation or printing, processes leading to morphological changes open new possibilities of microstructurization. Series of experiments made under different experimental conditions brought evidence of two different reaction pathways: introduction of OH- and C=O-groups at the polystyrene pathways is mainly due to the reaction of reactive oxygen species (hydroxyl radicals, atomic oxygen, ozone) produced in the gas phase between the VUV-radiation source and the substrate. However, oxidative fragmentation leading to morphological changes, oxidation products of low molecular weight and eventually to mineralization of the organic substrate is initiated by electronic excitation of the polymer leading to C–C-bond homolysis and to a complex oxidation manifold after trapping of the C-centred radicals by molecular oxygen. The pathways of oxidative functionalization or fragmentation could be differentiated by FTIR-ATR analysis of irradiated polystyrene surfaces before and after washing with acetonitrile and microscopic fluorescence analysis of the surfaces secondarily functionalized with the N,N,N-tridodecyl-triaza-triangulenium (TATA) cation. Ozonization of the polystyrene leads to oxidative functionalization of the polymer surface but cannot initiate the fragmentation of the polymer backbone. Oxidative fragmentation is initiated by electronic excitation of the polymer (contact-mode AFM analysis), and evidence of the generation of intermediate C-centred radicals is given e.g. by experiments in the absence of oxygen leading to cross-linking (solubility effects, optical microscopy, friction-mode AFM) and disproportionation (fluorescence).

Thermal Degradation of Short Nylon -6 Fiber-Reinforced Styrene Butadiene Rubber Composite

The thermal properties of short Nylon-6 fiber-reinforced Styrene butadiene rubber (SBR) composites were studied by Thermogravimetric Analysis (TGA). The effect of epoxy-based bonding agent on thermal degradation of the gum and the composites was also studied. The thermal stability of the SBR was enhanced in the presence of Nylon-6 fibers and the stability of the composites increased in the presence of bonding agent. The epoxy resin did not significantly change the thermal stability of SBR gum vulcanizate. Results of kinetic studies showed that the degradation of SBR and the short nylon fiber-reinforced composites with and without bonding agents followed first-order kinetics.

Thermal degradation of short polyester fiber polyurethane elastomer composite

The thermal degradation of short polyester fiber reinforced polyurethane composites with and without different bonding agents has been studied by thermogravimetric analysis . It was found that degradation of the polyurethane takes place in two steps and that of the composites takes place in three steps. With the incorporation of 30 phr of fiber in the matrix , the onset of degradation was shifted from 230 to 238 ° C. The presence of bonding agents in the virgin elastomer and the composite gave an improved thermal stability . Results of kinetic studies showed that the degradation of polyurethane and the reinforced composites with and without bonding agents follows first -order reaction kinetics

Thermal degradation of short kevlar fibre thermoplastic polyurethane composite

The thermal degradation of short kevlar fibre-thermoplastic polyurethane (TPU) composites has been studied by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). TGA showed that the thermal degradation of TPU takes place in two steps with peak maxima (T1max and T2ma,) at 383°C and 448°C, respectively. In the presence of 10-40 phr of short kevlar fibres, T1_ and T2max were shifted to lower temperatures. The temperature of onset of degradation was increased from 245 to 255°C at 40 parts per hundred rubber (phr) fibre loading. Kinetic studies showed that the degradation of TPU and kevlar-TPU composite follows first-order reaction kinetics. The DSC study showed that there is an improvement in thermal stability of TPU in the presence of 20 phr of short kevlar fibres.

Studies on Catalysis by Nano Titania Modified with Metals and Nonmetals

Semiconductor photocatalysis has received much attention during last three decades as a promising solution for both energy generation and environmental problems. Heterogeneous photocatalytic oxidation allows the degradation of organic compounds into carbon dioxide and water in the presence of a semiconductor catalyst and UV light source. The •OH radicals formed during the photocatalytic processes are powerful oxidizing agents and can mineralise a number of organic contaminants. Titanium dioxide (TiO2), due to its chemical stability, non-toxicity and low cost represents one of the most efficient photocatalyst. However, only the ultraviolet fraction of the solar radiation is active in the photoexcitation processes using pure TiO2 and although, TiO2 can treat a wide range of organic pollutants the effectiveness of the process for pollution abatement is still low. A more effective and efficient catalyst therefore must be formulated. Doping of TiO2 was considered with the aim of improving photocatalytic properties. In this study TiO2 catalyst was prepared using the sol-gel method. Metal and nonmetal doped TiO2 catalysts were prepared. The photoactivity of the catalyst was evaluated by the photodegradation of different dyes and pesticides in aqueous solution. High photocatalytic degradation of all the pollutants was observed with doped TiO2. Structural and optical properties of the catalysts were characterized using XRD, BET surface area, UV-Vis. DRS, CHNS analysis, SEM, EDX, TEM, XPS, FTIR and TG. All the catalysts showed the anatase phase. The presence of dopants shifts the absorption of TiO2 into the visible region indicating the possibility of using visible light for photocatalytic processes.

Dayglow Emissions on Mars and Venus

An attempt has been made in this thesis to model some of the emissions observed by SPICAM and SPICAV on Mars and Venus, respectively, viz., CO Cameron band, CO+ 2 ultraviolet doublet, N2 triplet bands, atomic oxygen green (5577 A), red doublet (6300, 6364 A), and ultraviolet (2972 A) emissions. One of major sources of these emissions is photoelectron impact ionization/excitation. In this thesis, an electron degradation model based on Monte Carlo technique has been developed to calculate the production/excitation rates of above mentioned emissions due to electron impact. The limb brightness pro les of emissions are calculated and compared with the observations wherever available. The e ect of various model input parameters on dayglow emissions intensities is also evaluated

Modelling of Ultraviolet and Vissible Emissions in Comets

Comets are the spectacular objects in the night sky since the dawn of mankind. Due to their giant apparitions and enigmatic behavior, followed by coincidental calamities, they were termed as notorious and called as `bad omens'. With a systematic study of these objects modern scienti c community understood that these objects are part of our solar system. Comets are believed to be remnant bodies of at the end of evolution of solar system and possess the material of solar nebula. Hence, these are considered as most pristine objects which can provide the information about the conditions of solar nebula. These are small bodies of our solar system, with a typical size of about a kilometer to a few tens of kilometers orbiting the Sun in highly elliptical orbits. The solid body of a comet is nucleus which is a conglomerated mixture of water ice, dust and some other gases. When the cometary nucleus advances towards the Sun in its orbit the ices sublimates and produces the gaseous envelope around the nucleus which is called coma. The gravity of cometary nucleus is very small and hence can not in uence the motion of gases in the cometary coma. Though the cometary nucleus is a few kilometers in size they can produce a transient, extensive, and expanding atmosphere with size several orders of magnitude larger in space. By ejecting gas and dust into space comets became the most active members of the solar system. The solar radiation and the solar wind in uences the motion of dust and ions and produces dust and ion tails, respectively. Comets have been observed in di erent spectral regions from rocket, ground and space borne optical instruments. The observed emission intensities are used to quantify the chemical abundances of di erent species in the comets. The study of various physical and chemical processes that govern these emissions is essential before estimating chemical abundances in the coma. Cameron band emission of CO molecule has been used to derive CO2 abundance in the comets based on the assumption that photodissociation of CO2 mainly produces these emissions. Similarly, the atomic oxygen visible emissions have been used to probe H2O in the cometary coma. The observed green ([OI] 5577 A) to red-doublet emission ([OI] 6300 and 6364 A) ratio has been used to con rm H2O as the parent species of these emissions. In this thesis a model is developed to understand the photochemistry of these emissions and applied to several comets. The model calculated emission intensities are compared with the observations done by space borne instruments like International Ultraviolet Explorer (IUE) and Hubble Space Telescope (HST) and also by various ground based telescopes.

Diversity and effectiveness of tropical mangrove soil microflora on the degradation of polythene carry bags

The diversity and load of heterotrophic bacteria and fungi associated with the mangrove soil from Suva, Fiji Islands, was determined by using the plate count method. The ability of the bacterial isolates to produce various hydrolytic enzymes such as amylase, gelatinase and lipase were determined using the plate assay. The heterotrophic bacterial load was considerably higher than the fungal load. There was a predominance of the gram positive genus, Bacillus. Other genera encountered included Staphylococcus, Micrococcus, Listeria and Vibrio. Their effectiveness on the degradation of commercial polythene carry bags made of high density polyethylene (HDPE) and low density polyethylene (LDPE) was studied over a period of eight weeks in the laboratory. Biodegradation was measured in terms of mean weight loss, which was nearly 5 % after a period of eight weeks. There was a significant increase in the bacterial load of the soil attached to class 2 (HDPE) polythene. After eight weeks of submergence in mangrove soil, soil attached to class 1 and class 3 polythene mostly had Bacillus (Staphylococcus predominated in class 2 polythene). While most of the isolates were capable of producing hydrolytic enzymes such as amylase and gelatinase, lipolytic activity was low. Class 2 HDPE suffered the greatest biodegradation.

Formation of an unusual copper(II) complex from the degradation of a novel tricopper(II) carbohydrazone complex

An unusual copper(II) complex [Cu(L1a)2Cl2] CH3OH H2O H3O+Cl (1a) was isolated from a solution of a novel tricopper(II) complex [Cu3(HL1)Cl2]Cl3 2H2O (1) in methanol, where L1a is 3-(2-pyridyl)triazolo [1,5-a]-pyridine, and characterized with single crystal X-ray diffraction study. The tricopper(II) complex of potential ligand 1,5-bis(di-2-pyridyl ketone) carbohydrazone (H2L1) was synthesized and physicochemically characterized, while the formation of the complex 1a was followed by time-dependant monitoring of the UV–visible spectra, which reveals degradation of ligand backbone as intensity loss of bands corresponding to O?Cu(II) charge transfer

Process Improvement of Coir Pith Degradation Involving White Rot Fungi By Substitution of Urea With Nitrogen Fixing Bacteria and Application of Biodegraded Coir Pith as Plant Growth Medium

In this study, a novel improved technology could be developed to convert the recalcitrant coir pith into environmental friendly organic manure. The standard method of composting involves the substitution of urea with nitrogen fixing bacteria viz. Azotobacter vinelandii and Azospirillum brasilense leading to the development of an improved method of coir pith. The combined action of the microorganisms could enhance the biodegradation of coir pith. In the present study, Pleurotus sajor caju, an edible mushroom which has the ability to degrade coir pith, and the addition of nitrogen fixing bacteria like Azotobacter vinelandii and Azospirillum brasilense could accelerate the action of the fungi on coir pith. The use of these microorganisms brings about definite changes in the NPK, Ammonia, Organic Carbon and Lignin contents in coir pith. This study will encourage the use of biodegraded coir pith as organic manure for agri/horti purpose to get better yields and can serve as a better technology to solve the problem of accumulated coir pith in coir based industries