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DDM 33 Features
Continuous record of % expansion with millisecond
resolution
No
dead time—Measurement starts milliseconds after
immersion
Fully automated test cycle with auto-standardization
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Paper
and Paperboard expand when re-wetted after they have
come off the paper machine. Since some converting
processes involve considerable re-wetting, the
expansivity of the paper when it comes in contact with liquid is a critical factor and has to be controlled
tightly. Typical examples are the printing of newsprint,
the impregnation of decorative laminating papers, and
the application of adhesive to labels.
 Measuring
Principle. The paper sample is
loaded in the sample holder and held in place between
two clamps, which are spring loaded and assert a low
tensile force. The instrument goes through an automatic
standardization procedure allowing for varying lengths
of the test piece. After immersing the sample into the
test liquid at high speed the paper starts to expand. This
expansion is monitored with a precision
displacement transducer. The computer uses the stored initial length
information to calculated in millisecond intervals the
expansion of the paper in % from its original dry
length. The temperature of the test liquid can be raised
up to 195 °F. The test apparatus is available as a
stand-alone unit or as an accessory for the emco DPM 33.
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