Electroless plating of copper layer on surfaces of urea-formaldehyde microcapsule particles containing paraffin for low infrared emissivity

A copper coating was deposited by electroless plating on the surfaces of urea-formaldehyde microcap- sules containing paraffin （UFP） particles. This composite microcapsule structure had low infrared OR） emissivity and maintained a constant temperature, and could be used in IR stealth applications. The eiectroless copper layer formation and its micro-appearance, and the effect of the copper layer on the IR emissivity and thermal properties of the composite microcapsules were investigated. The IR emissivity of the composite microcapsules at wavelengths of 1-14 μm gradually decreased with increasing copper mass on the surface. After formation of an integrated copper layer, the rate of IR emissivity decrease was lower. This is because the copper coating improves the surface conductivity of the UFP; a high conductivity results in high reflectivity, which leads to a decrease in IR emissivity. The lowest IR emissivity achieved was 0.68. The phase-change enthalpy of the composite microcapsules decreased with increasing amount of copper coated on the surface because of the high density of copper. When the mass increase of the UFP after electroless copper plating was about 300%, the composite microcapsules had low IR emissivity （about 0.8） and a high phase-change enthalpy （80J/g）.

Characterisation and seasonal variations of particles in the atmosphere of rural, urban and industrial areas：Organic compounds

Atmospheric aerosol samples（PM2.5–0.3, i.e., atmospheric particles ranging from 0.3 to2.5 μm） were collected during two periods： spring–summer 2008 and autumn–winter 2008–2009, using high volume samplers equipped with cascade impactors. Two sites located in the Northern France were compared in this study： a highly industrialised city（Dunkirk） and a rural site（Rubrouck）. Physicochemical analysis of particulate matter（PM） was undertaken to propose parameters that could be used to distinguish the various sources and to exhibit seasonal variations but also to provide knowledge of chemical element composition for the interpretation of future toxicological studies. The study showed that PM2.5–0.3concentration in the atmosphere of the rural area remains stable along the year and was significantly lower than in the urban or industrial ones, for which concentrations increase during winter.High concentrations of polycyclic aromatic hydrocarbons（PAHs）, dioxins, furans and dioxin like polychlorinated biphenyls（DL-PCBs）, generated by industrial activities, traffic and municipal wastes incineration were detected in the samples. Specific criteria like Carbon Preference Index（CPI） and Combustion PAHs/Total PAHs ratio（CPAHs/TPAHs） were used to identify the possible sources of atmospheric pollution. They revealed that paraffins are mainly emitted by biogenic sources in spring–summer whereas as in the case of PAHs, they have numerous anthropogenic emission sources in autumn-winter（mainly from traffic and domestic heating）.