Influence of Humidity

DPC has in recent years been applied to studies on a range of photopolymers including DF 2000 photopolymer [6], cinnamonyl methacrylate-glycidyl methacrylate copolymer [7], multiethylene glycol dimethacrylate [8], Ebecryl 270 (aliphatic urethane diacrylate [8], 1,6-hexanediol diacrylate and 2-hydroxy-2 methyl phenyl propane-l-one (Darocure 1173) [2], epoxy acrylates [9], epoxy vinyl ether formulations [10], polyarylates, maleimides and vinyl ethers [11], hydroxylated polyimides [12], polystyrene-poly-w-butyl acrylate copolymers [13], and 3,3,5-trimethylcyclohexane-l-phenol adducts [1]. 

Cho and co-workers [10] used photo DSC (Le., DPC and IR spectroscopy) to show that, in anthracene photosensitised polymerisations of various epoxy-vinyl ether based formulations, the formulations containing more than 5% anthracene exhibited a two-stage exothermic reaction. As the concentration of anthracene photosensitiser increased, the first exotherm decreased and the second one increased. 

Thermal Analysis of Polymers, Rapra Review Report No.95, Rapra Technology Ltd, Shawbury, Shrewsbury, UK, 1997, Volume 8, No.ll. 

Moore in IJY Curing, Science and Technology, Volume 2, Ed., S.P. Pappas, Technology Marketing Corporation, Stamford, CT, USA, 1978, p.134. 

Rogler, H. Markert, B. Stapp and F. Zapf, Polymer Preprints, 1988, 29, 528. 

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Finally mention may be made about the influence of humidity on the electrical insulating properties of plastics. Once again the polymers may be classified into two groups, those which do not absorb water and those which do. The nonabsorbent materials are little affected by humidity whereas the insulation characteristics of the absorbent materials deteriorate seriously. These latter materials are generally certain polar materials which all appear capable of forming some sort of bond, probably a hydrogen bond, with water. Three reasons may be given for the deleterious effects of the water. 

The higher the content of melamine, the higher is the stability of the hardened resin against the influence of humidity and water (hydrolysis resistance) [17, 45,46]. Resins containing melamine can be characterized by the molar ratio F (NH2)i or by the triple molar ratio F U M. The mass portion of melamine in the resin can be described as being based on the liquid resin or based on the total mass of urea and melamine in the resin (Table 6). MUF-resin hardener addition usually is distinctly higher than in UF-resins. 

Figure 17 Influence of humidity on the characteristic values of flax fiber SMC molded plastics [58].

Table 14 Influence of Humidity on Flexural Strength and Fracture Toughness of Cellulose Fiber Reinforced Cements [78]...

Kamens, R.M., Guo, Z., Fulcher, J.N., Bell, D.A. (1988) Influence of humidity, sunlight, and temperature on daytime decay of polyaromatic hydrocarbons on atmospheric soot particles. Environ. Sci. Technol. 22, 103-108. 

The following experimental observations qualitatively summarize the influence of humidity on the CO sensing process [66]. 

Otto, H. W., and R. H. Daines. Plant injury by air pollutants Influence of humidity on stomatal apertures and plant response to ozone. Science 163 1209-1210. 1%9. 

The water lattice may be an important element in forming the ordered thymine structure necessary for dimerization, as pointed out by Beukers and Berends.37 Thymine can crystallize from solution as a monohydrate (a real hydrate)38 in whose crystal lattice one thymine is directly above another. The influence of humidity upon dimer yield in dry films may be connected with monohydrate formation, and monohydrate formation in frozen solutions may be the reason for the almost theoretically maximum quantum yields for dimer formation.31 The possible existence of aggregates in frozen aqueous solutions is supported by a tenfold increase in purine phosphorescence at 44°K produced by the presence of 1% ethanol and by a blue shift of excitation and emission spectra.39... 

Kamens, R., Z. Guo, J. Fulcher, and D. Bell, Influence of Humidity, Sunlight, and Temperature on the Daytime Decay of Polyaromatic Hydrocarbons on Atmospheric Soot Particles, Environ. Sci. Technol., 22, 103-108(1988). 

Figure 9 Influence of humidity on the photocatalytic oxidation of o-xylene. (From Ref. 19.)...

Clausen, P.A., Xu, Y., Kofoed-Sorensen, V., Little, J.C. and Wolkoff P. (2007) The influence of humidity on the emission of di-(2-ethylhexyl) phthalate (DEHP) from vinyl flooring in the emission cell FLEC . Atmospheric Environment, 41, 3217-24. 

It should be kept in mind during the rectification that methylchlorosilanes are easily hydrolysed even under the influence of humidity in air, and the hydrogen chloride formed in the hydrolysis corrodes the equipment. Thus, all equipment and communications should be absolutely dry, and the obtained products should be collected, separated and transported in the absence of moisture. If these conditions are observed, it is possible to produce all technological equipment from common brand steel. 

P. Lodewyckx and E. F. Vansant, Influence of humidity on adsorption capacity from the Wheeler-Jonas model for prediction of breakthrough times of water immiscible organic vapors on activated carbon beds, Am. Ind. Hyg. Assoc. J. 60, 612-617 (1999). 

The influence of water on the dissipation of surface charges can be studied by adjusting the environmental humidity which controls the water amount offered for adsorption. The influence of humidity on the charge stability is illustrated in Fig. 4. For three polar polymer samples the... 

The chemistry of a finely divided solid with high surface area is at the borderline between molecular chemistry and physics of solid surfaces. The surface of a finely divided amorphous silica may be understood as a two-dimensional projection of the three-dimensionally linked silicon dioxide tetrahedra. By this the chemistry of the fumed silica surface is dominated by Si-O-Si units and, in particular, dangling surface Si-0 bonds, which will create silanol groups under the influence of humidity at ambient temperature. 

Measurements of current-voltage (I/U) characteristics have been made with an account of the concept of tunable electronic material with pores in oxide of semiconductors (TEMPOS) [3-6]. TEMPOS structures, depending on the preparation details, may resemble the features of resistors, capacitors, diodes, transistors, photocells or sensors. It is worth noting that similar I/U characteristics under the influence of humidity were observed earlier [4] on the TEMPOS samples consisting of a SiOi layers with ion tracks covered with continuous fullerite layers on Si substrates. This structure has got the name of MOSBIT (moistutre sensor with buckminsterflillerene in the tracks). 

Badham, E.R. (1985). The influence of humidity upon transpiration and growth in Psilocybe cubensis. Myco/og/a, 77, 932-939. 

Geiss, F., Schlitt, H., Klose, A. Reproducibility in thin-layer chromatography Influence of humidity, chamber form, and chamber atmosphere, Zeitschrift jilr Anal. Chem., 1965,... 

This is to say that in practice for a given particleboard, we have to determine the emission at 23oC and 55% RH, and the influence of humidity in order to classify the board for the appropriate use category. 

Y. Insemi and S. Mori, Dissolution tests of commercial tablets containing potassium Influences of humidity on release of potassium salts from coated tablets [in Japanese], Yukuzuiguku 41, 177-183(1981). 

Influence of humidity on an electron beam evaporated Si02 film deposited on a substrate of 400°C [38]... 

Figure 6-29. Influence of humidity (water vapor) on ozone yield in a DBD in room-temperature oxygen.

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