Determination of shrinkage of the hottest POF envi

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Determination of shrinkage rate of POF environmental friendly heat shrinkable film

1 instrument

1.1 constant temperature bath: used to contain liquid heat transfer medium. The volume shall be sufficient to accommodate the membrane frame

1.2 the manufacturer of liquid testing machine teaches you that the heat transfer medium is generally glycerin

1.3 frame: two frames embedded with metal, whose size is slightly larger than the sample, and the distance between the two outer metals is mm, should not affect the free shrinkage of the sample

2 operation steps

2.1 preparation of sample:

cut 3M from the outer end of each roll of film for inspection, discard it, and then evenly cut 100mm parallel to the longitudinal direction of the film along the width direction of the film × Three 100mm square samples. Accurate to 0.1mm

2.2 the standard environment for sample state adjustment and test shall be in accordance with gb2918

temperature: 23 ± 2 ℃; Humidity: the adjustment time in the normal humidity state is more than 4 hours

2, but what you get back is the calibration certificate 3 draw a symmetry axis in the longitudinal and transverse directions of the sample for marking, and indicate the longitudinal and transverse directions. Place the sample flat between the two frames, and then quickly immerse it in the constant temperature medium of ± 2 ℃ operated by the machine according to the operating instructions, shrink freely, take it out after 20s, immerse it in the standby normal temperature bath, cool it for 5S, take out the sample, stand horizontally, and measure the dimension of the longitudinal and transverse symmetry axis within 30 minutes, accurate to 1mm, And researchers also hope to do their part to record the measurement data in order to achieve this goal

3 the result indicates that

shrinkage is calculated according to the following formula:

s =

where: s: shrinkage,%

l0: the length of the sample before heating, mm

l: the length of the sample after shrinkage, mm


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