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Abstract

Transient heat transfer is studied and compared in two plane-parallel composite walls and one EPIDIAN 53 epoxy resin wall acting as a matrix for both composites. The first of the two walls is made of carbon-epoxy composite; the other wall is made of glass-epoxy composite, both with comparable thickness of about 1 mm and the same number of carbon and glass fabric layers (four layers). The study was conducted for temperatures in the range of 20-120 °C. The results of the study of thermal diffusivity which characterizes the material as a heat conductor under transient conditions have a preliminary character. Three series of tests were conducted for each wall. Each series took about 24 h. The results from the three series were approximated using linear functions and were found between (0.7-1.35) x 10-7m2/s. In the whole range of temperature variation, the thermal diffusivity values for carbon-epoxy composite are from 1.2 to 1.5 times higher than those for the other two materials with nearly the same thermal diffusivity characteristics.
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Abstract

A novel herbicidal controlled release formulation composed of (2,4-dichlorophenoxy) acetic acid (2,4-D) chemically bonded to biodegradable (R,S)-3-hydroxybutyric acid oligomers was investigated. The synthesis of (R,S)-3-hydroxy butyric acid oligomers was carried out via the ring opening polymerization of β-butyrolactone initiated by 2,4-dichlorophenoxy acetic potassium salt in the presence of complexing agents. The formed oligomers were characterized by size exclusion chromatography, proton magnetic resonance and electrospray mass spectrometry in order to fi nd out their molar mass distribution and molecular structures. An assessment of biological effectiveness of the obtained herbicidal formulation was carried out in the greenhouse vs. Sinapis alba var. Nakielska. A promotion of the controlled release formulation with decreased water solubility and with low vapor pressure of the active ingredient, instead of traditional formulations of 2,4-dichlorophenoxy acetic acid may help to ensure a greater safety for workers and reduce the risk of dissemination of the active ingredient in the soil profi le.
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