Thermal and hydraulic analysis of multilayered asphalt pavements as active solar collectors

The fulfillment of current environmental aims like reducing fossil fuel consumption or greenhouse gas emissions entails the development of new technologies that enable the use of cleaner, cheaper and renewable energies. Furthermore, the need to improve energy efficiency in buildings encourages scientists and engineers to find new ways of harvesting energy for later uses. The use of asphalt pavements as active solar collectors is introduced in this article. Several authors have studied the use of roads as an energy source before. However, a new technology is presented in which a multilayered pavement with a highly porous middle layer is used instead of a solar collector with an embedded pipe network. These collectors are fully integrated within the road infrastructure and may offer low cost solar energy for water heating. The paper includes a brief comment on the state-of-the-art. Then, a broad methodology is presented in which data, materials and procedures needed to run the tests are fully described. Finally, the results of the laboratory tests are stated and discussed. The prototype used in the laboratory provided excellent thermal efficiency. However, these good results contrast with the low flow rate levels registered during the tests. Thus, although this technology seems to be very promising, new experimental tests should be performed before an effective application is possible.This paper is based on the initial literature review for the Fenix Project. The development of the Fenix Project (www.proyectofenix.es) has been possible thanks to the financial contribution of the Center for Technological and Industrial Development (CDTI) within the framework of the Ingenio 2010 programme, through the CENIT Programme. The companies and research centers involved in the project wish to express their gratitude for the contribution

Studies of Polymerization of Acrylic Monomers Using Luminescence Probes and Differential Scanning Calorimetry

A fiber optic system has been designed to couple calorimeter and fluorimeter equipment for in situ monitoring of polymerization reactions by both techniques simultaneously. Two acrylic monomers (cyclohexyl methacrylate, CHM, and 2-ethylhexyl acrylate, EHA) were studied at different temperatures. Pyrene (Py) was employed at a low concentration (≤10⁻⁴ mol/L) as a fluorescence probe. The emission spectrum of pyrene shows a broad band peaking at 390 nm, whose intensity grows with polymerization progress. A correlation with conversion degree could be established by collecting fluorescence intensity through the optical fiber at different polymerization times. For the more flexible polymer formed, poly(ethylhexyl acrylate) (PEHA), Py emission sharply increases only when high conversions are reached and continues increasing for a long time after the limiting conversion is attained. For CHM polymerizations, S-shaped curves are found. Isochronal plots of intensity vs. scaled conversion allow elaboration of master curves for the peak emission. Data at 50°C for CHM cannot be fitted to the master curve, and this is explained in terms of vitrification.The authors acknowledge the financial support of this work by the Consejeria de Educación of Comunidad de Madrid (CAM 247 /92) and the Comisión Interministerial de Ciencia y Tecnología (MAT93-0823)

Effect of the morphology of two phase polymer blends on glass transition temperature

Paper derivado del Póster presentado al Congreso: International Conference on Advanced Materials Processing Technologies (AMPT'01)Blends of poly(cyclohexylmethacrylate), PChMA, with poly(vinylacetate), PVAc, were prepared by casting THF and chloroform solutions. A calorimetric and morphologic study was performed. Differential scanning calorimetry investigations of the blends show two glass transition temperature that give evidence of inmiscibility. For polymer less flexible (PChMA) was observed an enhancement of Tᵍ by 20 °C approximately in blends of PVAc-rich composition. Epifluorescence microscopy, using PChMA labelled by copolymerization pirenyl-methylmethacrylate, Py, shows also phase separation providing imaging of the distribution of PChMA in the different domains and in the matrix. Blends containing 80% w/w PChMA show a bicontinuous primary morphology suggesting a spinodal phase separation mechanism. The 50 and 20% PChMA samples show morphologies composed of PChMA-rich domains in a matrix composed by PVAc mainly. Blends with domain–matrix morphology present a higher Tᵍ than pure homopolymer more rigid (PChMA) due to packing in microphases in matrix of more flexible polymer (PVAc)

Fluorescence monitoring of polymerization reaction. A new method for treating fluorescence experimental data

A new method has been found for monitoring polymerization reactions in situ and in real time. The first moment of fluorescent emission, 〈ν〉=∑IF(ν)ν/∑IF(ν) is calculated from fluorescence spectra as a function of polymerization time and can be successfully correlated with the conversion of functional groups, obtained by an independent technique, with a very low level of experimental scatter. The statistical analysis of the method has been performed; some simple computer experiments allowed to study the influence of the most important experimental variables yielding the confidence interval of 〈ν〉 as a function of the noise to signal ratio. This method was applied with stepwise polyaddition (epoxide curing) and polymerization by free radical mechanisms. 5-Dimethylaminonaphthalene-1-sulfonamide derivatives, 4-dialkylamino-4′-nitrostilbene and pyrene were used as probes and/or labels. Other methods reported in the literature have been applied also. Comparison with them reveals that the first moment method is more reliable for monitoring polyaddition reactions.Authors wish to thank European Commission (BE97-4472) and CAM (07N/0002/1998) for financial support

Water absorption in polyaminosiloxane-epoxy thermosetting polymers

Water absorption is a common problem in epoxy-based composites, especially in interfacial regions. In contrast to epoxy resins, silicones are hydrophobic materials. Modification of epoxy thermosets with silicones should improve physical properties because of decrease in water diffusion. Bisphenol-A diglycidyl ether (DGEBA) was cured with a synthesised aminopropyl perfunctionalised siloxane. Water absorption was analysed by different techniques, including near infrared (FTIR) water absorbance at 5200 cm−1 and gravimetry. Fick’s law diffusion coefficients were calculated. Swelling equilibrium of the resin was also analysed. Absorbed water catalyses the curing reaction strongly, allowing to reach high conversions

Pyrene Fluorescence as a Probe for the Monitoring of Polymerization Processes: Simultaneous DSC and Fluorescence Study

The polymerization of cyclohexylmethacrylate was monitored, over a wide temperature range, by simultaneous differential scanning calorimetry (DSC) and fluorimetry (FL); the equipment for both being optically coupled. Pyrene was used as a fluorescent probe. There was excellent agreement between the exothermic peak time obtained by DSC and the time at which the maximum gradient was obtained in the fluorescence intensity–time curves, but only for temperatures above 60°C, Activation energies for the gel effect onset were obtained for both, the conversion–time and intensity–time curves being concordant except for data at low temperatures, below 60°C. It was concluded that vitrification occurs at temperatures below 60°C and its presence was demonstrated by fluorimetry, by means of the conversion change associated with the fluorescence intensity jumpΔα(off-on).This research was supported by CICYT MAT93-0823

Morphology of Epoxy/Polyorganosiloxane Reactive Blends

The morphology of the diglycidyl ether of bisphenol-A / poly(3-aminopropylmethylsiloxane) (DGEBA/PAMS) reactive blends was studied by fluorescence techniques as a function of the initial composition. Some fluorescence results were compared with those from optical and electron microscopy investigations. Several morphological aspects were studied including the distribution of PAMS in the blend. The microsegregation of PAMS was discussed in terms of diffusion restriction of DGEBA through the PAMS dispersed phase.This research was supported by the EU, Brite-EuRam , and by CAM, programa de grupos estratégicos, contrato programa 2000-2003. The authors gratefully acknowledge the contribution of Dr. I. F. Pierola from UNED in the acquisition of the epifluorescence images presented in this work

Chemical imaging of phase separated polymer blends by fluorescence microscopy

Blends of poly(vinylacetate) (PVAc) and poly(cyclohexylmethacrylate) (PCHMA) labeled by copolymerization with 4-methacryloylamine-48-nitrostilbene (Sb), with (1-pyrenylmethyl)methacrylate (Py), or with 3-(methacryloylamine)propyl-N-carbazole (Cbz) were prepared by casting dilute solutions in tetrahydrofurane (THF) or chloroform. Films about 10 mm thick were formed. Phase separation in two types of domains is observed by transmission optical microscopy (TOM) and epifluorescence microscopy (EFM): small craters of 1 to 10 mm placed at the polymer–air interface and larger domains, on the scale of 100 mm. The morphology of samples depends on the composition of the polymer blend and on solvent. The green fluorescence of Sb, the violet of Py, or the blue of Cbz provides imaging of the distribution of PCHMA in the different domains and in the matrix. It is thus observed that (i) superficial craters and large domains are formed mainly by PCHMA and (ii) the matrix is composed of PVAc in films cast from THF and it is a blend of the two polymers, homogeneous at the submicrometric scale, for chloroform. The emission intensity of Py, recorded by microfluorescence spectroscopy (MFS), yields a mapping similar to imaging detection. It is remarkable that in films cast from chloroform, the smaller domains are distributed with a 2D hexatic order disrupted by dislocations and disclinations, whereas in films cast from THF, a larger heterogeneity is found, denoting different mechanisms of solvent evaporation.This work was supported by CICYT (Spain) and Brite-Euran (EU) under Grants PB95-0247 and BE-97-4672, respectively

Photophysics of a pyrene probe grafted onto silanized glass fiber surfaces

Glass fibers have been silanized with γ-aminopropyltriethoxysilane. 1-pyrenesulphonyl chloride (PSC) has been grafted onto the fibers via adduct formation with the amine functionality. Absorption spectra from SPC stock solutions shows aggregation. Emission spectra from the fibers also reveal aggregation of the cromophore at extremely low concentration (10⁻⁹ mol/g).This work has been supported by projects CAM 247/92 and CICYT MAT93-0823

Vaccination Against Porcine Circovirus-2 Reduces Severity of Tuberculosis in Wild Boar

Dr. D. Risco was supported by a Torres Quevedo Grant of the Ministerio de Economía y Competitividad of Spain (PTQ14-06663 and RYC-2016-21120) and by the postdoctoral programme of the Gobierno de Extremadura (Ref PO14024). E. Serrano was funded by the Spanish Ministerio de Economia y Competitividad (MINECO) through a Ramon y Cajal agreement (RYC-2016-21120).Tuberculosis (TB) in wild boar (Sus scrofa) may be affected by coinfections with other pathogens, such as porcine circovirus type 2 (PCV2). Therefore, sanitary measures focused on controlling PCV2 could be useful in reducing the impact of TB in this wild suid. The aim of this study was to explore whether vaccination against PCV2 targeting young animals affects TB prevalence and TB severity in wild boar. The study was conducted on a game estate in mid-western Spain. Seventy animals of ages ranging from 4 to 8 months were captured, individually identified, vaccinated against PCV2 and released, forming a vaccinated group. Not-captured animals cohabiting with the vaccinated wild boar constituted the control group. Animals from both groups were hunted between 2013 and 2016 and a TB diagnosis based on pathological assessment and microbiological culture was made in all of them. The effect of PCV2 vaccination on TB prevalence and severity was explored using generalized lineal models. Whereas TB prevalence was similar in vaccinated and control groups (54.55 vs. 57.78%), vaccinated animals showed less probabilities to develop generalized TB lesions. Furthermore, mean TB severity score was significantly lower in vaccinated animals (1.55 vs. 2.42) suggesting a positive effect of PCV2 vaccination