Latex Stage Blending of Natural Rubber and Poly(Vinyl Chloride ) for Improved Mechanical Properties

A novel method of blending natural rubber with polyvinylchloride in the latex stage was developed, Dioctyl phthalate (DOP) and Amine terminated natural rubber (ATNR) were used as plasticisers, for improving the mechanical properties of these blends. Properties of the latex stage blends were compared with those of dry blends. Latex stage blends showed superior mechanical properties compared to the blends prepared in the dry state. The ageing resistance, oil resistance and processability were found to be improved by latex stage blending.

Metrological assessment of a portable analyzer for monitoring the particle size distribution of ultrafine particles

Adverse health effects caused by worker exposure to ultrafine particles have been detected in recent years. The scientific community focuses on the assessment of ultrafine aerosols in different microenvironments in order to determine the related worker exposure/dose levels. To this end, particle size distribution measurements have to be taken along with total particle number concentrations. The latter are obtainable through hand-held monitors. A portable particle size distribution analyzer (Nanoscan SMPS 3910, TSI Inc.) was recently commercialized, but so far no metrological assessment has been performed to characterize its performance with respect to well-established laboratory- based instruments such as the scanning mobility particle sizer (SMPS) spectrometer. The present paper compares the aerosol monitoring capability of the Nanoscan SMPS to the laboratory SMPS in order to evaluate whether the Nanoscan SMPS is suitable for field experiments designed to characterize particle exposure in different microenvironments. Tests were performed both in a Marple calm air chamber, where fresh diesel particulate matter and atomized dioctyl phthalate particles were monitored, and in microenvironments, where outdoor, urban, indoor aged, and indoor fresh aerosols were measured. Results show that the Nanoscan SMPS is able to properly measure the particle size distribution for each type of aerosol investigated, but it overestimates the total particle number concentration in the case of fresh aerosols. In particular, the test performed in the Marple chamber showed total concentrations up to twice those measured by the laboratory SMPS—likely because of the inability of the Nanoscan SMPS unipolar charger to properly charge aerosols made up of aggregated particles. Based on these findings, when field test exposure studies are conducted, the Nanoscan SMPS should be used in tandem

Applications of cardanol in rubber processing

This research project explores the utilization of cardanol in various capacities for rubber processing. Cardanol is a phenol with a long side chain in the meta position of the benzene ring. It is obtained by the vacuum distillation of cashew Hut shell liquid (CNSL) which is a cheap agro-byproduct. In this study, the plasticizer property of cardanol was investigated in silica filled and HAF black filled NR, NBR, EPDM and CR by comparing cure characteristics and mechanical properties of vulcanizates containing conventional plasticizer with those containing cardanol as plasticizer. The co-activator, antioxidant and accelerator properties were investigated in gum samples of NR, NBR, EPDM and CR by comparing the properties of vulcanizates which contain conventional co-activator, antioxidant and accelerator with those in which each of them was replaced by cardanol. The general effectiveness of cardanol was investigated by determination of cure time , measurement of physical and mechanical properties, ageing studies, crosslink density, extractability, FTIR spectra, TGA etc.The results show that cardanol can be a substitute for aromatic oil in both silica filled and HAF black filled NR. Again, it can replace dioctyl phthalate in both silica filled and HAF black filled NBR. Similarly, cardanol Can replace naphthenic oil in silica filled as well as HAF black filled EPDM and CR. The cure characteristics and mechanical properties are comparable in all the eight cases. The co-activator property of cardanol is comparable to stearic acid in all the four rubbers. The cure characteristics and mechanical properties in this case are also comparable. The antioxidant ,property of cardanol is comparable to TQ in all the four rubbers. The antioxidant property of cardanol is comparable to TQ in all the four case of NBR and EPDM.The accelerator property of cardarlol is comparable with CBS in the case of NBR and EPDM. No accelerator property is observed in the case of NR. The accelerator property of cardanol in CR is not negligible when compared with TMTD.

Kinetic multi-layer model of gas-particle interactions in aerosols and clouds (KM-GAP): linking condensation, evaporation and chemical reactions of organics, oxidants and water

We present a novel kinetic multi-layer model for gas-particle interactions in aerosols and clouds (KM-GAP) that treats explicitly all steps of mass transport and chemical reaction of semi-volatile species partitioning between gas phase, particle surface and particle bulk. KM-GAP is based on the PRA model framework (Pöschl-Rudich-Ammann, 2007), and it includes gas phase diffusion, reversible adsorption, surface reactions, bulk diffusion and reaction, as well as condensation, evaporation and heat transfer. The size change of atmospheric particles and the temporal evolution and spatial profile of the concentration of individual chemical species can be modelled along with gas uptake and accommodation coefficients. Depending on the complexity of the investigated system, unlimited numbers of semi-volatile species, chemical reactions, and physical processes can be treated, and the model shall help to bridge gaps in the understanding and quantification of multiphase chemistry and microphysics in atmo- spheric aerosols and clouds. In this study we demonstrate how KM-GAP can be used to analyze, interpret and design experimental investigations of changes in particle size and chemical composition in response to condensation, evaporation, and chemical reaction. For the condensational growth of water droplets, our kinetic model results provide a direct link between laboratory observations and molecular dynamic simulations, confirming that the accommodation coefficient of water at 270 K is close to unity. Literature data on the evaporation of dioctyl phthalate as a function of particle size and time can be reproduced, and the model results suggest that changes in the experimental conditions like aerosol particle concentration and chamber geometry may influence the evaporation kinetics and can be optimized for eðcient probing of specific physical effects and parameters. With regard to oxidative aging of organic aerosol particles, we illustrate how the formation and evaporation of volatile reaction products like nonanal can cause a decrease in the size of oleic acid particles exposed to ozone.

Kinetic multi-layer model of gas-particle interactions in aerosols and clouds (KM-GAP): linking condensation, evaporation and chemical reactions of organics, oxidants and water

We present a novel kinetic multi-layer model for gas-particle interactions in aerosols and clouds (KMGAP) that treats explicitly all steps of mass transport and chemical reaction of semi-volatile species partitioning between gas phase, particle surface and particle bulk. KMGAP is based on the PRA model framework (P¨oschl-Rudich- Ammann, 2007), and it includes gas phase diffusion, reversible adsorption, surface reactions, bulk diffusion and reaction, as well as condensation, evaporation and heat transfer. The size change of atmospheric particles and the temporal evolution and spatial profile of the concentration of individual chemical species can be modeled along with gas uptake and accommodation coefficients. Depending on the complexity of the investigated system and the computational constraints, unlimited numbers of semi-volatile species, chemical reactions, and physical processes can be treated, and the model shall help to bridge gaps in the understanding and quantification of multiphase chemistry and microphysics in atmospheric aerosols and clouds. In this study we demonstrate how KM-GAP can be used to analyze, interpret and design experimental investigations of changes in particle size and chemical composition in response to condensation, evaporation, and chemical reaction. For the condensational growth of water droplets, our kinetic model results provide a direct link between laboratory observations and molecular dynamic simulations, confirming that the accommodation coefficient of water at 270K is close to unity (Winkler et al., 2006). Literature data on the evaporation of dioctyl phthalate as a function of particle size and time can be reproduced, and the model results suggest that changes in the experimental conditions like aerosol particle concentration and chamber geometry may influence the evaporation kinetics and can be optimized for efficient probing of specific physical effects and parameters. With regard to oxidative aging of organic aerosol particles, we illustrate how the formation and evaporation of volatile reaction products like nonanal can cause a decrease in the size of oleic acid particles exposed to ozone.

An ESR study of the radiolysis of semi-crystalline ethylene-propylene copolymers containing DOP mobilizer

The radiolysis of a poly(ethylene-co-propylene), Elpro, marketed by Thai Polypropylene Co. Ltd for the manufacture of medical goods has been investigated at 77 K. Calcium stearate was blended with the Elpro as a processing aid; and dioctyl phthalate, DOP, was added in various amounts as a radiation stabilizer. The ESR spectra of Elpro and Elpro+Ca were very similar and characterized principally by the presence of PP a-carbon radicals. The spectra of the samples containing DOP were similar to those for Elpro but with an additional narrow singlet arising from DOP radicals. On annealing the irradiated polymers to higher temperatures, the singlet was lost between 250 and 270 K, and at room temperature the principal radicals remaining were allyl radicals. The G-values for radical formation at 77 K for Elpro and Elpro+Ca at 77 K were 3.0 and 3.2, respectively, but incorporation of DOP resulted in lower G-values, ranging from 1.6 to 1.4 for 0.5 and 2.5 phr DOP, respectively.(c) 2005 Wiley Periodicals, Inc.

A rheology study of high-energy radiolysis of a semicrystalline ethylene-propylene copolymer containing DOP mobilizer

The ractiolysis of a poly(ethylene-co-propylene), Elpro grade P 750 J, marketed by Thai Polypropylene Co. Ltd. for the manufacture of medical goods, was investigated at ambient temperature and melt rheology measured. The roles of calcium stearate, blended with the Elpro as a processing aid, and dioctyl phthalate (DOP), added in various amounts as a radical scavenger, were assessed. Following radiolysis, G' and the viscosity of the polymer melts at 453 K both decreased with increasing radiation dose, even when the mobilizer was present. The results indicated that although the DOP did scavenge radicals, it did not protect the polymer from net chain scission in a low-dose regimen. The value of (G(S) - 4G(X)) was approximately 0.6-0.7. (c) 2006 Wiley Periodicals, Inc.

Studies on the ageing behaviour of Polyvinylchloride/ammonium perchlorate composite solid propellant

The effects of ageing on the properties of a complete polyvinyl chloride — dibutyl phthalate — ammonium perchlorate solid propellant have been studied by measurements of burning rates, thermal decomposition rates (by thermogravimetry and DTA) and calorimetric values. Ageing leads to loss of HCl by dehydrochlorination and a corresponding increase in heat of combustion.

Nanocomposites of crosslinked starch phthalate and silane modified nanoclay: Study of mechanical, thermal, morphological, and biodegradable characteristics

Biodegradable composites comprising of modified starch and modified nanoclay have been prepared. Starch has been modified by esterification and subsequently crosslinked. The thermal, mechanical, and biodegradation characteristics of the composites have been investigated. The compressive properties of the composites with the addition of nanoclay were twice that of crosslinked starch phthalate without addition of nanoclay. Predictive theories were used to analyze the obtained experimental results. SEM studies on fracture morphology indicated quasi-brittle fracture. Flexural properties showed considerable improvement due to nanoclay addition. The water uptake increased up to 6% nanoclay, beyond which the uptake decreased. Biodegradation studies showed an initial time lag prior to the onset of degradation.

Phthalate mediated hydrogelation of a pyrene based system: a novel scaffold for shape-persistent, self-healing luminescent soft material

Two-component super-hydrogelation triggered by the acid-base interaction of a L-histidine appended pyrenyl derivative (PyHis) and phthalic acid (PA) was reported. The use of isomeric isophthalic or terephthalic acid or other comparable acids in place of PA does not lead to salt formation and therefore hydrogelation is not observed. Excimer formation of the pyrenyl unit has not been detected although the PyHis : PA = 1: 1 system undergoes extensive self-assembly in aqueous solution. The synergistic effect of intermolecular H-bonding forces, pi-pi stacking, electrostatic interactions, etc. is found to be responsible for robust hydrogel formation. Development of chiral supramotecular assemblies has been verified through circular dichroism spectroscopy. Morphological investigations involving the PyHis : PA = 1: 1 system show vesicular nano-structures with a definite bilayer width at relatively low concentrations. The latter fuses to construct coiled-coil left-handed helical fibers upon increase in the concentrations of the gelators. The intertwining of the resultant helical fibers eventually results in hydrogel formation. The probable bilayer packing in the self-assembled structures has been probed using X-ray diffraction (XRD) studies and lanthanide sensitization, which suggests that the polar imidazolium hydrogen phthalate unit of the gelator forms the head group and faces the hydrophilic water environment while the hydrophobic pyrenyl units sit inside the hydrophobic core of the bilayer. The hydrogel exhibits multi-stimuli responsiveness including thixotropic behavior. In addition, shape-persistent as well as rapid self-healing behaviour of the hydrogel was established. Furthermore load-bearing characteristics of the hydrogel have also been demonstrated.

Effects of constructed wetland system on the removal of dibutyl phthalate (DBP)

Phthalic acid esters (PAEs) have become widely diffused in the environment via the manufacturing process. Numerous experiments have shown that the bioaccumulation of PAEs occurred in the aquatic and terrestrial food chain; meanwhile, it was found that some of PAEs were considered as potential carcinogens, teratogens and mutagens. In this research, two vertical/reverse-vertical flow constructed wetland systems were set up to study its removal efficiency of dibutyl, phthalate (DBP) pollution. The results showed that the constructed wetland system could remove DBP effectively, and the removal rates reached nearly 100%. Substrate microorganism and enzymatic activities probably played key roles during DBP removal, and the removal of DBP probably mainly took place in the upper layer of chamber A in the constructed wetland systems. (C) 2007 Elsevier GmbH. All rights reserved.

Enzymatic activities in constructed wetlands and di-n-butyl phthalate (DBP) biodegradation

The bioaccumulation of phthalate acid esters (PAEs) from industrial products and their mutagenic action has been suggested to be a potential threat to human health. The effects of the most frequently identified PAE, Di-n-butyl phthalate (DBP), and its biodegradation, were examined by comparison of two small scale plots (SSP) of integrated vertical-flow constructed wetlands. The influent DBP concentration was 9.84 mg l(-1) in the treatment plot and the control plot received no DBP. Soil enzymatic activities of dehydrogenase, catalase, protease, phosphatase, urease, cellulase, beta-glucosidase, were measured in the two SSP after DBP application for 1 month and 2 months, and 1 month after the final application. Both treatment and control had significantly higher enzyme activity in the surface soil than in the subsurface soil (P < 0.001) and greater enzyme activity in the down-flow chamber than in the up-flow chamber (P < 0.05). In the constructed wetlands, DBP enhanced the activities of dehydrogenase, catalase, protease, phosphatase and inhibited the activities of urease, cellulase and beta-glucosidase. However, urease, cellulase, beta-glucosidase activities were restored 1 month following the final DBP addition. Degradation of DBP was greater in the surface soil and was reduced in sterile soil, indicating that this process may be mediated by aerobic microorgansims. DBP degradation fitted a first-order model, and the kinetic equation showed that the rate constant was 0.50 and 0.17 d(-1), the half-life was 1.39 and 4.02 d, and the r(2) was 0.99 and 0.98, in surface and subsurface soil, respectively. These results indicate that constructed wetlands are able to biodegrade organic PA-Es such as DBP. (c) 2005 Elsevier Ltd. All rights reserved.

Determination of phthalate acid esters plasticizers in plastic by ultrasonic solvent extraction combined with solid-phase microextraction using calix[4]arene fiber

Ultrasonic solvent extraction combined with solid-phase microextraction (SPME) with calix[4]arene/hydroxy-terminated silicone (C[4]/OHTSO) oil coated fiber was used to extract phthalate acid esters (PAEs) plasticizers in plastic, such as blood bags, transfusion tubing, food packaging bag, and mineral water bottle for analysis by gas chromatography (GC). Both extraction parameters (i.e. extraction time, extraction temperature, ionic strength) and conditions of the thermal desorption in a GC injector were optimized by analysis of eight phthalates. The fiber shows wonderful sensitivity and selectivity to the tested compounds. Owing to its high thermal stability (380 degreesC), the carryover effect that often encountered when using conventional fibers can be reduced by appropriately enhancing the injector temperature. The method showed linear response over two to four orders of magnitude with correlation coefficients (r) better than 0.996, and limits of detection (LOD) ranged between 0.006 and 0.084 mug l(-1). The relative standard deviation values obtained were less than or equal to 10%. bis-2-Ethylhexyl phthalate (DEHP) was the sole analyte detected in these plastics and recoveries were in the ranges 95.5-101.4% in all the samples. (C) 2004 Elsevier B.V. All rights reserved.

Removal of dibutyl phthalate by a staged, vertical-flow constructed wetland

Two sets of small scale systems of staged, vertical-flow constructed wetlands (VFCW) were operated in a greenhouse to study the purification of dibutyl phthalate (DBP) in admeasured water. Each system consisted of two chambers in which water flowed downward in chamber I and then upward in chamber 2. The systems were intermittently fed with wastewater under a hydraulic load of 420 mm(.)d(-1). The measured influent concentrations of DBP in the experimental system were 9.84 mg(.)l(-1), while the other system was used as a control and received no DBP. Effluent concentrations of the treated system averaged 5.82 mug(.)l(-1) and were far below the Chinese DBP discharge standard of less than or equal to0.2 mg(.)l(-1). These results indicate the potential purification capacity of this new kind of constructed wetland in removing DBP from a polluted water body.