GC analysis of extractive compounds in beech woodVarious highly hydrophobic beech wood lipids were characterized and their quantities measured in hexane extracts by GC, using short and long capillary columns. More polar compounds were also identified in acetone extracts. Triglycerides, steryl esters, sterols, unsaturated fatty acids, as well as various monosaccharide units were determined as possible pollutants of papermaking systems.

Due to its chemical composition, waste sludge generated in the paper industry may be used as a raw material for brick production. Brick manufacture is limited to the warmer months of the year whereas sludge is produced continuously by different effluent treatment devices. Therefore, it has to be stored until further processing. For this reason, it is essential that it is not subject to significant chemical and microbiological decomposition during storage. In the experiment, sludge from a tissue paper mill was tested for its stability. It was stored for several weeks during winter and summer periods in a pile, 2 m in height, in an open but covered store. Different leachable organic and inorganic compounds indicating possible ongoing deterioration processes, as well as pH value, redox potential, temperature, humidity and dry matter content were evaluated weekly in water extracts of homogenized sludge samples. According to the test results, the material may be considered to be chemically and microbiologically stable as there was practically no emission of odorous and toxic compounds such as H2S, NH3 and butyric acid despite prolonged storage times and elevated environmental temperatures. All the microbial species identified in the sludge during storage belong to the typical microflora of the environment.

S U M M A R Y :Course and kinetics of the isothermal bulk polymerization of methyl methacrylate were studied by differential scanning calorimetry. The initiator used was 2,2'-azoisobutyronitrile. The polymerization was investigated at temperatures between 70 and 90°C at constant initiator concentration, 5,2.10-2 mol d~n -~. The heat of polymerization at 7OoC is -52,3 kJ/mol (-12,5 kcal/mol) and decreases, i.e. becomes more negative, with increasing temperature. Initial rate constants for the polymerization were also determined and from them the overall activation energy, 77 kJ/mol (18,4 kcal/mol), which is in good agreement with the literature value. Another series of polymerization experiments were performed at 80°C with variable amounts of the initiator. The heat of polymerization found is -52,8 kJ/mol (-12,6 kcal/mol) and depends only slightly o n the initiator concentration. The overall rate of polymerization at low degrees of conversion depends on the square root of the initiator concentration. These findings thus corroborate the conclusion reached by other authors that differential scanning calorimetry is a useful method for studying the kinetics of polymerization. Z U S A M M E N F A S S U N G :Mit Hilfe der Differential-Scanning-Kalorimetrie (DSC) wurden der Verlauf und die Kinetik der isothermen Polymerisation des Methylmethacrylates in Substanz untersucht. Als Initiator wurde 2,2'-Azoisobutyronitril verwendet. Die Polymerisation wurde bei Temperaturen zwischen 70 und 90°C mit konstanter Initiatorkonzentration, 5,2. lo-' mol/dm3, ausgefiihrt. Die Polymerisationswarme betragt bei 70°C -52,3 kJ/mol (-12,5 kcal/mol) und nimmt rnit steigender Temperatur ab (sie wird negativer). Es wurden auch Geschwindigkeitskonstanten der Polymerisation im stationaren Zustand und aus ihnen die Bruttoaktivierungsenergie 77 kJ/mol (1 8,4 kcal/mol) bestimmt, die gut mit Literaturangaben iibereinstimmt. Eine andere Reihe von Experimenten wurde bei 80°C mit verschiedenen Initiatormengen durchgefiihrt. Der dabei gefundene Wert der Polymerisationswarme -52,8 kJ/mol (-12,6 kcal/mol) ist von der Initiatormenge nur wenig abhangig. Die Bruttogeschwindigkeit der Polymerisation bei kleinen Umsatzen ist der Wurzel aus der Initiatorkonzentration proportional. Diese Ergebnisse zeigen in nbereinstimmung mit den Befunden anderer Autoren, daR die Scanning-Kalorimetrie eine brauchbare Methode zum Studium der Kinetik der Polymerisation ist.

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