IN-PRODUCT ENVIRONMENTAL-PROTECTION - EVALUATION OF CHEMICAL-EMISSIONS FROM RESIN FORTIFIED RESISTANCE SPOT-WELDING IN THE AUTOMOBILE-INDUSTRY .1. THERMAL-ANALYSIS MASS-SPECTROMETRY AND LABORATORY PYROLYSIS MEASUREMENTS WITH THE GERMAN VCI OVEN

The protection of the working and living environment can be ameliorate d by in-product environmental protection. Products and processing tech nologies can be developed with fewer chemical emissions and result in less direct or lifetime environmental and workplace hazards. Laborator y studies were made to evaluate the organic emissions of the new joini ng technique, the resin fortified resistance spot welding. Laboratory investigations were carried out by thermoanalytic methods, coupled the rmal analysis/mass spectrometer (TA/MS) studies, and pyrolysis experim ents in the so-called German VCI oven. Especially in the case of weldi ng temperatures over 1200 degrees C, the evaluation of toxic and hazar dous substances by pyrolytic processes is of special interest. We stud ied pyrolysis products, formed from the used oil (anticorrosive and au xiliary additive) and epoxy resin material. These materials were teste d in the TA/MS instrument at different atmospheres to obtain informati on about principal pyrolytic products. The VCI combustion device simul ated thermal degradation processes at different preselected temperatur es. Incineration was performed at temperatures of 400, 600, 800, 1000 and 1200 degrees C with an air or nitrogen flow rate of LOO ml/min. Th e volatile combustion products were collected. Polycyclic aromatic hyd rocarbons (PAHs) were trapped by XAD-4-resin and analyzed by GC/MS and aldehydes respectively on a 2,4-dinitrophenylhydrazine (DNPH) coated silica cartridge and analyzed by HPLC-DAD method. While incineration a t 400 and 600 degrees C yields mainly characteristic fragments of the matrix and aldehydes, burning at 800 and 1000 degrees C leads to more polycyclic aromatic compounds resulting from aromatization and carboni zation reactions. At 1200 degrees C, the amount of pyrolytic products, mainly PAH, decreased significantly.