Particulate Fillers in Thermoplastics

The characteristics of particulate filled thermoplastics are determined by four factors: component properties, composition, structure and interfacial interactions. The most important filler characteristics are particle size, size distribution, specific surface area and particle shape, while the main matrix property is stiffness. Segregation, aggregation and the orientation of anisotropic particles determine structure. Interfacial interactions lead to the formation of a stiff interphase considerably influencing properties. Interactions are changed by surface modification, which must be always system specific and selected according to its goal. Under the effect of external load inhomogeneous stress distribution develops around heterogeneities, which initiate local micromechanical deformation processes determining the macroscopic properties of the composites

GC-ITD analysis of chlortoluron and its metabolites in cereals

Chlortoluron and its metabolites have been determined in cereals by gas chromatography. Chlortoluron is pyrolyzed to the corresponding phenylisocyanate, which is determined by GC with nitrogen-phosphorous detection (NPD) and confirmed by GC with ion trap detection (ITD). N-demethyl metabolites of chlortoluron are determined, after conversion to the perfluoroacyl derivatives, by GC with ion trap detection by single ion monitoring;N-ethyl-p-chloroacetanilide is used as internal standard. The hydroxymethyl metabolite, mainly present as β-glucoside, can be analyzed, after enzymatic hydrolysis with β-glucosidase and conversion to the ethyl derivative, by GC with ion trap detection by SIM;N-ethylchlortoluron is used as internal standard. The methods proposed are reproducible and sensitive enough for determination of these compounds at residue levels in cereals. © 1993 Friedr. Vieweg & Sohn Verlagsgesellschaft mbH

Chlortoluron levels and selectivity in wheat cultivars

Chlortoluron determination in seedlings of four wheat cultivars have been carried out by gas liquid chromatography with alkali flame-ionization detection. Recoveries through the method were always higher than 70% and the limit of detection was 0.01 ppm. Herbicide levels have been determined at different times after treatment. No significant differences among cultivars have been found in chlortoluron levels at the end of 24 h treatment, while six days after treatment susceptible cultivars showed levels of chlortoluron clearly higher than tolerant cultivars. A good correlation was observed between herbicide level and plant fresh weight in the studied cultivars six days after treatment. © 1989