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Improved EMI shielding
December 1992
Additives for Polymers
TECHNICAL NOTES Improved
EMI shielding
OptimizingPisment
distribution in masterbatch production
Researchers at the State University of New York in Buffalo (USA) are “growing” fine hairs on carbon fibres and powders by catalytically modifying them in different atmospheres. It is envisaged that the improved connectivity and increased surface area of carbon in the compound could enable the carbon loading to be reduced for a given level of conductivity, thereby improving the processability of the compound. French compounding extruder manufacturer Clextral has developed a masterbatch image analysis system to optimize the design of its twin screw machines. The company says that traditional methods of analysing dispersion, such as microtomy or hot film pressing, are not appropriate for hard mineral fillers or glass fibres, which give a distorted quantitative view. The image analysis system works by observing samples under a microscope. It digitizes the image, and then uses computer analysis to identify grains of residual agglomerates, to size and count them. Analysis results are obtained in 45 to 90 minutes. Clextral has used the process to assess the dispersing power of screw elements and thereby optimize the geometries. It has also used it to optimize the dosing points and order of addition of pigments and fillers, and optimize machine running conditions. The analysis process is to be extended to the selection of polymers, pigments, fillers, waxes and dispersing agents, and to quality control in commercial production.
MATERIALS
END USE TRADE NAME(S) CHEMICAL TYPE COMPANY
FIRE RETARDANT HOSTAFLAM TP AP750 Ammonium polyphosphate Hoechst AG, Postfach 80 03 20, D-W 6230, Frankfurt am Main 80, (Germany).
PRODUCT DETAILS
Halogen-free intumescent grade that can be processed at higher temperatures than previous grades.
e1992 Elsevier Science Publishers Ltd.
Additives for Polymers
TECHNICAL NOTES Improved
EMI shielding
OptimizingPisment
distribution in masterbatch production
Researchers at the State University of New York in Buffalo (USA) are “growing” fine hairs on carbon fibres and powders by catalytically modifying them in different atmospheres. It is envisaged that the improved connectivity and increased surface area of carbon in the compound could enable the carbon loading to be reduced for a given level of conductivity, thereby improving the processability of the compound. French compounding extruder manufacturer Clextral has developed a masterbatch image analysis system to optimize the design of its twin screw machines. The company says that traditional methods of analysing dispersion, such as microtomy or hot film pressing, are not appropriate for hard mineral fillers or glass fibres, which give a distorted quantitative view. The image analysis system works by observing samples under a microscope. It digitizes the image, and then uses computer analysis to identify grains of residual agglomerates, to size and count them. Analysis results are obtained in 45 to 90 minutes. Clextral has used the process to assess the dispersing power of screw elements and thereby optimize the geometries. It has also used it to optimize the dosing points and order of addition of pigments and fillers, and optimize machine running conditions. The analysis process is to be extended to the selection of polymers, pigments, fillers, waxes and dispersing agents, and to quality control in commercial production.
MATERIALS
END USE TRADE NAME(S) CHEMICAL TYPE COMPANY
FIRE RETARDANT HOSTAFLAM TP AP750 Ammonium polyphosphate Hoechst AG, Postfach 80 03 20, D-W 6230, Frankfurt am Main 80, (Germany).
PRODUCT DETAILS
Halogen-free intumescent grade that can be processed at higher temperatures than previous grades.
e1992 Elsevier Science Publishers Ltd.