Impact Of Atmosphere Research Articles

Life in the Hothouse: How a Living Planet Survives Climate Change

Review: Life in the Hothouse: How a Living Planet Survives Climate Change By Melanie Lenart Reviewed by Elery Hamilton-Smith Charles Sturt University, Australia Lenart, Melanie. Life in the Hothouse: How a Living Planet Survives Climate Change. Tucson, AZ: University of Arizona Press, 2010. 236pp. ISBN 9780816527236.US$22.95, paperback. This is a fine book. Amongst the plethora of writing on climate change, this one is remarkable for its comprehensiveness, integration and clarity. Although dealing with a very complex topic, its clarity is such that any reasonably well-read would find it both fascinating and informative while most academics would also welcome its clarity. The author opens with the recognition that Lovelock’s Gaia concept provides an appropriate framework for understanding climate change. So her overall strategy is clearly based within the metaphorical process. At the same time her forthright position emerges in describing Descartes’ mechanistic philosophy as outdated. Her own approach is to lead the reader on a conceptual journey in search of a clear and holistic understanding of climate. Her own insights into current scientific research are explained and integrated while traveling through the mindscapes of our world perceived as Gaia. Adopting the searching journey as a research model is still relatively new but has demonstrated its value in dealing with complexity. Those who have adopted it see it as a parallel to using a systematic journey of observation to understand complex geographic landscapes. The Palaeo-evidence tells us that the world has passed through regular cycles of climate change, even though the periods of change are more or less tumultuous in character in the short term and scientists have often found themselves disagreeing in trying to interpret the meaning of short term changes. But the real evidence tells us that each cycle is a period of slow global warming within which gales, cyclones and hurricanes re-distribute tropical hot air to cooler latitudes, thus controlling the overall global warming. The impacts of these movements are most marked in their migration from the tropics to formerly temperate climatic zones. Thus, the boundaries of cyclonic zones are respectively moving to the North and South. Lenart draws upon the Gaia metaphor by pointing out that when we experience over-heating, our bodies perspire and we use fans to reduce the impact of the hot atmosphere. In very much the same way, the Gaia world uses cyclones and other storms to move hot air away from the overheated tropics. Having been very aware of how far we have been able to enrich our own understanding of climate change by the Palaeo-climatic research, I now venture into the future. Lenart (and other climate change scholars) have been cautious in examining the potential impacts upon geomorphic change. Clearly the movement of immense loads of sediments and boulders do lead to significant changes in landscapes. The disappearance of deep ice cover will similarly alter the immense pressures upon rocks and even crustal margins. In turn some of these changes will be a major factor in generation of tsunamis and earthquakes. I believe these phenomena urgently demand systematic assessment with a view to developing effective predictive models to aid planning for geomorphic recovery. Perhaps our long-distance descendents will be able to draw upon such work in planning for management of the next climatic change event.

The impact of the atmosphere on the Eyjafjallajökull 2010 eruption plume

The eruption of Eyjafjallajökull volcano in 2010 lasted 39 days, 14 April–23 May. The eruption had two explosive phases separated by a phase with lava formation and reduced explosive activity. During the explosive phases there were episodes of strong winds that advected ash to the south and southeast leading to widespread disruptions in air traffic. The height of the eruption plume was monitored with a weather radar and with web cameras mounted with a view of the volcano. Three different types of the impact of the ambient atmosphere on the eruption plume are described. First, the weather situation throughout the eruption has been analyzed. The frequency of northerly wind component is found to be unusually high, or 71% in comparison to 49% on average in spring. Secondly, during the effusive phase of the eruption diurnal variation was observed in the plume altitude and there is evidence that suggest that nocturnal inversions may have played a role, limiting the rise of the weak plume. Thirdly, images from a web camera were analyzed and the rise of individual cloud heads associated with explosions at the volcano vent mapped. The velocity profiles obtained largely agree with conceptual models of volcanic plumes.

English

  This study aims at exploring the theme of creating and managing store atmosphere of chain store supermarket from customer’s point of view. The findings from the study indicate: (1) The customer-perceived factors of store atmosphere of supermarket include 6 factors in 3 categories, that is, design factors, ambient factors (including intangible factors and visual stimulus) and social factors (including image of service personnel, image of other customers and environmental crowding); (2) Store atmospheric factors have significant positive correlation with customer approach behaviors, design factors being the most significant impact among all factors. Store atmospheric factors will influence not only customer emotions but also customer cognitive valuations of commodities and services. Customer cognitive valuations and emotional responses will affect customer approach behaviors significantly; meanwhile, customers’ cognitions and emotional responses will moderator the impact of store atmosphere on customer behaviors partially; (3) Customers with various characteristics (including different shopping planning, time urgency, environmental familiarity etc.) have significant differences in customer perceptions and behaviors in general. Finally, this study proposes specific suggestions and measures of how to create a pleasant store atmosphere in chain store supermarket according to results of empirical analyses.   Key words: Chain store supermarket, store atmosphere, customer perception, approach-avoidance behaviors.

Hetero-modulus alumina matrix nanoceramics and CMCs with extreme dynamic strength

Applying the well-known alumina powders for matrix, different oxide and non-oxide ceramic submicron and nano-particles as additive materials, and investigating the impact of nitrogen atmosphere on sintering; the authors successfully developed new hetero-modulus alumina matrix ceramic composite materials, reinforced with submicron and nanoparticles of α-Si3N4 β-Si3N4, Si2ON2, SiAlON and AlN. Thanks to the new compacting technology with high speed flying punches in vacuumed N2 atmosphere developed by authors, phase transformation of α-Si3N4 and β-Si3N4 into cubic c-Si3N4 can be observed, creating so-called Si3N4-diamond submicron and nanoparticles in alumina matrix. The α-Si3N4, β-Si3N4, Si2ON2, SiAlON, AlN and c-Si3N4 diamond submicron and nanoparticles reinforced alumina matrix hetero-modulus nanoceramics have excellent mechanical properties and extreme dynamic strength. The dynamic strength was tested through collision with high density metallic flying bodies, with speed higher than 900 m/sec. Analytical methods applied in this research were laser granulometry, scanning electron microscopy, X-ray diffraction and energy dispersive spectrometry. Digital image analysis was applied to microscopy results, to enhance the results of transformation.

Effects of mall atmosphere on mall evaluation: Teenage versus adult shoppers

What is the effect of mall atmosphere in mall evaluation? Is this effect mediated by self-congruity and functional congruity? Does the effect of mall atmosphere on mall evaluation differ between adult and teenage shoppers? If so how? The research reported in this paper attempts to answer the above questions. A survey of mall shoppers was conducted ( N=265) based on a mall intercept. The survey findings indicate that mall atmosphere positively affects functional congruity for both adults and teenage shoppers. However, as expected, the impact of atmosphere on self-congruity is only significant for teenagers. In turn, self-congruity and functional congruity positively affect mall evaluation for both adult and teenage shoppers.

Life in the hothouse: how a living planet survives climate change

The author opens with the recognition that Lovelock’s Gaia concept provides an appropriate framework for understanding climate change. So her overall strategy is clearly based within the metaphorical process. At the same time her forthright position emerges in describing Descartes’ mechanistic philosophy as outdated. Her own approach is to lead the reader on a conceptual journey in search of a clear and holistic understanding of climate. Her own insights into current scientific research are explained and integrated while traveling through the mindscapes of our world perceived as Gaia. Adopting the searching journey as a research model is still relatively new but has demonstrated its value in dealing with complexity. Those who have adopted it see it as a parallel to using a systematic journey of observation to understand complex geographic landscapes. The Palaeo-evidence tells us that the world has passed through regular cycles of climate change, even though the periods of change are more or less tumultuous in character in the short term and scientists have often found themselves disagreeing in trying to interpret the meaning of short term changes. But the real evidence tells us that each cycle is a period of slow global warming within which gales, cyclones and hurricanes re-distribute tropical hot air to cooler latitudes, thus controlling the overall global warming. The impacts of these movements are most marked in their migration from the tropics to formerly temperate climatic zones. Thus, the boundaries of cyclonic zones are respectively moving to the North and South. Lenart draws upon the Gaia metaphor by pointing out that when we experience over-heating, our bodies perspire and we use fans to reduce the impact of the hot atmosphere. In very much the same way, the Gaia world uses cyclones and other storms to move hot air away from the overheated tropics.

Impacts of Ocean–Atmosphere Coupling on Tropical Cyclone Intensity Change and Ocean Prediction in the Australian Region

Abstract This study investigates the impact of atmosphere–ocean coupling on predicted tropical cyclone (TC) intensity change and the ocean response in the Australian region. The coupled model comprises the Australian Bureau of Meteorology’s Tropical Cyclone Limited-Area Prediction System (TC-LAPS) and a regional version of the BLUElink ocean forecasting system. A series of case study forecasts are presented and the differences between coupled and uncoupled forecasts, operational forecasts, and posterior objective analyses are compared. A coupled model ensemble is also developed that uses different first-order approximations of the effects of surface waves on surface stress in an inertial coupling method. In each of the cases, the use of reanalyzed sea surface temperatures significantly improves the prediction of TC intensity change in the intensification phase. The results show that dynamic air–sea coupling has a modest impact on intensity in cases where SST cooling is significant and is likely to be important for predicting the rate of TC intensification, peak intensity, and deintensification. Results also show that there is a definite coupled signal and suggest inherent biases in the atmospheric model that could potentially be removed. With different parameterizations of surface wave effects, results show modest sensitivity in TC intensity of up to 10 hPa in minimum surface pressure; however, in some cases there was significant sensitivity in the predicted ocean response. The results also highlight the relative increased complexity of tropical cyclone prediction in the Australian region compared to other regions. In cases where the forecast TC track was reasonably skillful, there were improvements in the predicted ocean response with respect to observations compared to an ocean reanalysis.

Impact of atmosphere and sub‐surface ocean data on decadal climate prediction

We present a set of idealised model experiments that investigate the impact of assimilating different amounts of ocean and atmosphere data on decadal climate prediction skill. Assimilating monthly average sub‐surface temperature and salinity data successfully initialises the meridional overturning circulation and produces skillful predictions of global ocean heat content. However, when sea surface temperature data is assimilated alone the predictions have much less skill, particularly in the extra‐tropics. The upper 2000m temperature and salinity observations currently provided by the Argo array of floats are therefore potentially well suited to initialising decadal climate predictions. We note however that we do not attempt to simulate the actual distribution of Argo floats. Assimilating data beneath 2000m always reduces the RMSE, with the most significant improvements in the Southern Ocean. Furthermore, assimilating six hourly atmospheric observations significantly improves the forecast skill within the first year, but has little impact thereafter.

Impact of diurnal atmosphere–ocean coupling on tropical climate simulations using a coupled GCM

The impacts of diurnal atmosphere–ocean (air–sea) coupling on tropical climate simulations are investigated using the SNU coupled GCM. To investigate the effect of the atmospheric and oceanic diurnal cycles on a climate simulation, a 1-day air–sea coupling interval experiment is compared to a 2-h coupling experiment. As previous studies have suggested, cold temperature biases over equatorial western Pacific regions are significantly reduced when diurnal air–sea coupling strategy is implemented. This warming is initiated by diurnal rectification and amplified further by the air–sea coupled feedbacks. In addition to its effect on the mean climatology, the diurnal coupling has also a distinctive impact on the amplitude of the El Nino-Southern Oscillation (ENSO). It is demonstrated that a weakening of the ENSO magnitude is caused by reduced (increased) surface net heat fluxes into the ocean during El Nino (La Nina) events. Primarily, decreased (increased) incoming shortwave radiation during El Nino (La Nina) due to cloud shading is responsible for the net heat fluxes associated with ENSO.

Mechanisms controlling the diurnal solar tide: Analysis using a GCM and a linear model

A general circulation model (GCM, HAMMONIA) and a linear model are used for analyzing the dynamics of the total diurnal solar tide in the mesosphere and lower thermosphere, comprising both the migrating and all nonmigrating components. A comparison between this tide in the GCM and in published observations is relatively favorable. The linear model uses monthly means from the GCM as background atmosphere and the diurnal heating rates from that model as forcing. The background atmosphere may be longitude‐dependent so that stationary planetary waves can be included. A straightforward analysis of corresponding effects is thus facilitated. To a large degree the seasonal variability of the diurnal tide is due to variations in the background atmosphere. In addition to corresponding previous results on the impact of the zonal mean atmosphere on the migrating tide, the thermospheric tide is shown to be strongly influenced by the variability of the absorption of solar radiation by O2. With regard to the nonmigrating tidal components, also, their most important forcing mechanisms are tropospheric as for the migrating tide below the thermosphere and their seasonal cycle is mostly controlled by variations of the background atmosphere. In the dynamics of these components, however, the planetary waves take an active role. They can cause reductions in the tidal amplitude by destructive interference with the directly forced nonmigrating tide, as for DS0 in February. The opposite effect of enhancing the tidal amplitude is also observed for DW2 in the same season. The component DE3 is controlled by an interplay between the variability of the zonal mean background and diurnal heating. The correct simulation of a meridional wind amplitude minimum in this tide during NH summer May–August seems to depend critically on the phase relation between the two.

The Influence of Atmospheric Noise and Uncertainty in Ocean Initial Conditions on the Limit of Predictability in a Coupled GCM

Abstract The influence of atmospheric stochastic forcing and uncertainty in initial conditions on the limit of predictability of the NCEP Climate Forecast System (CFS) is quantified based on comparisons of idealized identical twin prediction experiments using two different coupling strategies. In the first method, called the interactive ensemble, a single oceanic general circulation model (GCM; the Modular Ocean Model version 3 of GFDL) is coupled to the ensemble average of multiple realizations (in this case six ensemble members) of an atmospheric GCM (NCEP Global Forecast System). In the second method the standard CFS is used. The interactive ensemble is specifically designed to reduce the internal atmospheric dynamic fluctuations that are unrelated to the sea surface temperature anomalies via ensemble averaging at the air–sea interface, whereas in the standard CFS, the atmospheric noise (i.e., stochastic forcing) plays an active role in the evolution of the coupled system. In the identical twin experiments presented here, the perfect model approach is taken, thereby explicitly excluding the impact of model error on the estimate of the limit of predictability. The experimental design and the analysis separately consider how uncertainty in the ocean initial conditions (i.e., initial condition noise) versus uncertainty as the forecast evolves (i.e., noise due to internal dynamics of the atmosphere) impact estimates of the limit of predictability. Estimates of the limit of predictability are based on both deterministic measures (ensemble spread and root-mean-square error) and probabilistic measures (relative operating characteristics). The analysis examines both oceanic and atmospheric variables in the tropical Pacific. The overarching result is that noise in the initial condition is the primary factor limiting predictability, whereas noise as the forecast evolves is of secondary importance.

Impact of nitrogen atmosphere on sintering of alumina ceramics

Impact of nitrogen atmosphere on sintering of alumina ceramics

Experimental study of ash formation during pulverized coal combustion in O 2/CO 2 mixtures

The present paper was addressed to mineral transformations and ash formation during O 2/CO 2 combustion of pulverized coal. Four Chinese thermal coals were burned in a drop tube furnace to generate ashes under various combustion conditions. The ash samples were characterized with XRD analysis and 57Fe Mössbauer spectroscopy. The impacts of O 2/CO 2 combustion on mineral transformation and ash formation were explored through comparisons between O 2/CO 2 combustion and O 2/N 2 combustion. It was found that, O 2/CO 2 combustion did not significantly change the mineral phases formed in the residue ashes, but did affect the relative amounts of the mineral phases. The differences observed in the ashes formed in two atmospheres were attributed to the impact of the gas atmosphere on the combustion temperatures of coal char particles, which consequently influenced the ash formation behaviors of included minerals.

The influence of different atmosphere gases on the growth and structure of double-walled carbon nanotubes

To clarify the impact of different atmosphere gases on the growth and structure of double-walled carbon nanotubes (DWCNT), we used a graphite rod containing some catalyst as our anode and prepared DWCNTs with the arc-discharge method in an atmosphere of pure Ar, pure H2, and a mixture (1: 1 by volume) of Ar and H2 at different pressures, respectively. The Fe family metal-sulfide composite (FeS, NiS, CoS) used as the catalyst was mixed with high-purity graphite powder in a certain proportion and was then enclosed into a drilled hole in the anode. By altering the discharge conditions and examining the product of the DWCNT using high-resolution electron microscopy, we found the optimum growth condition to be the atmosphere of mixed (1: 1) Ar and H2, and the ratio (FeS: NiS: CoS: C = 1: 1: 1: 15 wt %) for the catalyst of the Fe family metal-sulfide composite.

Impact of Atmosphere–Ocean Coupling on the Predictability of Monsoon Intraseasonal Oscillations*

Abstract The impact of air–sea coupling on the predictability of monsoon intraseasonal oscillations (MISO) has been investigated with an atmosphere–ocean coupled model and its atmospheric component. From a 15-yr coupled control run, 20 MISO events are selected. A series of twin perturbation experiments have been conducted for all the selected events using both the coupled model and the atmosphere-only model. Two complementary measures are used to quantify the MISO predictability: (i) the ratio of signal-to-forecast error and (ii) the spatial anomaly correlation coefficient (ACC). In the coupled model, the MISO predictability is generally higher over the Indian sector than that over the western Pacific with a maximum of 35 days in the eastern equatorial Indian Ocean. Air–sea coupling significantly improves the predictability in almost the entire Asian–western Pacific region. The mean predictability of the MISO-related rainfall over its active area (10°S–30°N, 60°–160°E) reaches about 24 days in the coupled model and is about 17 days in the atmosphere-only model. This result suggests that including an interactive ocean allows the MISO predictability of an atmosphere-only model to be extended by about a week. The extended predictability is primarily due to the coupled model capturing the two-way interactions between the MISO and underlying sea surface. The MISO forces a coherent intraseasonal SST response in underlying ocean that in return exerts an external control on the future evolutions of the MISO. The break phase of the MISO is more predictable than the active phase in both the atmosphere-only model and the coupled model as revealed in the observations. Air–sea coupling appears to extend the MISO predictability uniformly regardless of the active or break phases.

Feldspathic clasts in Yamato-86032: Remnants of the lunar crust with implications for its formation and impact history

Low concentrations of Th and Fe in the Yamato (Y)-86032 bulk meteorite support earlier suggestions that Y-86032 comes from a region of the moon far distant from the Procellarum KREEP Terrain (PKT), probably from the lunar farside. 39Ar– 40Ar, Rb–Sr, Sm–Nd, and Sm-isotopic studies characterize the chronology of Y-86032 and its precursors in the mega regolith. One of the rock types present in a light gray breccia lithology is an anorthosite characterized by plagioclase with An ∼93, i.e., more sodic than lunar FANs, but with very low 87Rb/ 86Sr and 87Sr/ 86Sr similar to those of FANs. (FAN stands for Ferroan Anorthosite). This “An93 anorthosite” has Nd-isotopic systematics similar to those of nearside norites. A FAN-like “An97 anorthosite” is present in a second light-colored feldspathic breccia clast and has a more negative ε Nd value consistent with residence in a LREE-enriched environment as would be provided by an early plagioclase flotation crust on the Lunar Magma Ocean (LMO). This result contrasts with generally positive values of ε Nd for Apollo 16 FANs suggesting the possibility of assymetric development of the LMO. Other possible explanations for the dichotomy in ε Nd values are advanced in the text. The Y-86032 protolith formed at least 4.43 ± 0.03 Ga ago as determined from a Sm–Nd isochron for mineral fragments from the breccia clast composed predominantly of An93 anorthosite and a second clast of more varied composition. We interpret the mineral fragments as being predominatly from a cogenetic rock suite. An 39Ar– 40Ar age of 4.36–4.41 ± 0.035 Ga for a third clast composed predominantly of An97 anorthosite supports an old age for the protolith. Initial 143Nd/ 144Nd in that clast was −0.64 ± 0.13 ε-units below 143Nd/ 144Nd in reservoirs having chondritic Sm/Nd ratios, consistent with prior fractionation of mafic cumulates from the LMO. A maximum in the 39Ar– 40Ar age spectrum of 4.23 ± 0.03 Ga for a second sample of the same feldspathic breccia clast probably reflects some diffusive 40Ar loss. Lack of solar wind and lunar atmosphere implanted Ar in the light gray breccia clast allows determination of an 39Ar/ 40Ar age of 4.10 ± 0.02 Ga, which is interpreted as the time of initial brecciation of this litholgy. After correction for implanted lunar atmosphere 40Ar, impact melt and dark regolith clasts give Ar ages of 3.8 ± 0.1 Ga implying melt formation and final breccia assembly ∼3.8 Ga ago. Some breccia lithologies were exposed to thermal neutron fluences of ∼2 × 10 15 n/cm 2, only about 1% of the fluence experienced by some other lunar highlands meteorites. Other lithologies experienced neutron fluences of ∼1 × 10 15 n/cm 2. Thus, Y-86032 spent most of the time following final brecciation deeply buried in the megaregolith. The neutron fluence data are consistent with cosmogenic 38Ar cos cosmic ray exposure ages of ∼10 Ma. Variations among differing lithologies in the amount of several regolith exposure indicators, including cosmogenic noble gas abundances, neutron capture induced variations in Sm isotopic abundances, and Ir contents, are consistent with a period of early (>∼3.8 Ga ago) lunar regolith exposure, subsequent deep burial at >∼5 m depth, and ejection from the moon ∼7–10 Ma ago.

Impact of atmosphere, organic acids, and calcium on quality of fresh-cut ‘Kensington’ mango

Fresh-cut slices from ripe ‘Kensington’ mango ( Mangifera indica L.) were prepared aseptically and stored under various treatments at 3 °C. Treatments included reduced oxygen (2.5%), enhanced carbon dioxide (5–40%), organic acid application, calcium chloride application, and combinations of the above. Symptoms limiting shelf-life were characterised by tissue darkening, development of a ‘glassy’ appearance, surface desiccation, and loss of firmness. Reduced oxygen (2.5%) was effective at controlling tissue darkening and the development of a ‘glassy’ appearance, while calcium application (3%) was partly effective at controlling darkening. Calcium chloride however significantly slowed (but did not stop) loss of tissue firmness. Carbon dioxide (5–40%) and citric acid had little positive effect on shelf-life, with both treatments appearing to promote tissue softening. A combination of low oxygen and calcium allowed ‘Kensington’ slices to be held for at least 15 days at 3 °C.

Impact of Explicit Atmosphere–Ocean Coupling on MJO-Like Coherent Structures in Idealized Aquaplanet Simulations

Abstract This paper discusses the impact of the atmosphere–ocean coupling on the large-scale organization of tropical convection simulated by an idealized global model applying the Cloud-Resolving Convection Parameterization (CRCP; superparameterization). Because the organization resembles the Madden–Julian Oscillation (MJO), the results contribute to the debate concerning the role of atmosphere–ocean coupling in tropical intraseasonal oscillations. The modeling setup is an aquaplanet with globally uniform mean sea surface temperature (SST) of 30°C (tropics everywhere) in radiative–convective quasi equilibrium. The simulations apply an interactive radiation transfer model and a slab ocean model with a fixed oceanic mixed layer depth. Results from several 80- and 100-day-long simulations are discussed, where the only difference between the simulations is the prescribed oceanic mixed layer depth, which varied from 5 to 45 m. A simulation with a very deep oceanic mixed layer is also performed to represent constant-SST conditions. The simulations demonstrate that the interactive SST impedes the development of large-scale organization and has insignificant impact on the dynamics of mature MJO-like systems. The impediment is the result of a negative feedback between the large-scale organization of convection and SST, the convection–SST feedback. In this feedback, SST increases in regions of already suppressed convection and decreases in regions with enhanced convection, thus hindering the large-scale organization. Once developed, however, the MJO-like systems are equally strong in interactive and constant-SST simulations, and compare favorably with the observed MJO. The above impacts of the atmosphere–ocean coupling contradict the majority of previous studies using traditional general circulation models, where, typically, an enhancement of the intraseasonal signal occurs compared to prescribed-SST simulations. An explanation of this discrepancy is suggested.

Photostructural modifications in poly(methylphenylsilylene) thin films: Excitation wavelength and atmosphere dependence

Electronic (UV-vis) and vibrational absorption spectroscopies were used to examine the impact of incident photon energy and local atmospheric composition on the development of photo-induced structural changes in poly[(methyl)(phenyl)silylene] thin films. The relative impact of atmosphere on the magnitude and nature of photostructural modifications in this material is found to be enhanced under 3.68 eV photon exposure where the incident photon is resonant with the lowest energy absorption of the Si-Si-conjugated backbone structure. This is in contrast to a greater overall magnitude of photo-induced structural change, with limited atmospheric dependence, observed under 5.1 eV exposure, resonant with absorption transitions associated with the π-conjugated phenyl ring side group. These results provide insight into the underlying structural mechanisms contributing to the large refractive index changes typically observed in these materials.

Photo‐oxidation of polymers: Validation of oxygen uptake and relationship with extent of hydroperoxidation

AbstractIn this piece of work we focused our attention on the peroxidation step and alongside considered hydroperoxides as probes for the overall oxidative process. This technique of oxygen uptake actually monitors the amount of oxygen consumed during polymer degradation. Our present work aimed to investigate this technique to evaluate the oxygen uptake during in situ photoirradiation, under controlled atmosphere. Our experimental results clearly elucidate that the oxygen consumption data accounts for a very early stage of aging during the photo‐oxidation of polymers and provides us with an accurate and sensitive diagnosis about the formation of hydroperoxides. A straight‐line relationship was exhibited under our experimental conditions while observing a relation between oxygen pressure drop and hydroperoxide content in the polymer. This correlation was dependent upon the nature of polymer and of course on the aging conditions (temperature, irradiation, oxidative atmosphere). The impact of environmental atmosphere on aging was particularly kept in mind. To conclude, we emphasized that oxygen uptake is a promisingly powerful tool to identify the impact of the overall environmental parameters on the polymer photoaging. An important implication was on the understanding of atmospheric factors (including pollutants such as O3, NOx, etc.), which is usually given minor importance, on the degradation of polymer upon outdoor weathering. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006