Background

Plastic films and sheets are typically made by melting polymer material and then shaping it through processes like extrusion or calendaring. During this production, the material is stretched in the machine direction, and as it cools, some internal stresses remain. When reheated, these stresses can cause the material to shrink, altering its dimensions.

This shrinkage is crucial for quality and process control in plastic manufacturing. It helps assess process consistency, adjust production parameters, and understand material characteristics. Industries like packaging rely on shrinkage data to ensure precise fit after heat exposure.

In essence, shrinkage is a key factor in maintaining product quality and process efficiency in plastic film and sheet production.

Application

The FST-01 Film Free Shrink Tester is used to measure the unrestrained linear thermal shrinkage of plastic film and sheets at specified temperatures in a fluid medium. This device helps assess how much these materials will shrink when exposed to heat in real-world applications.

Test Process 

1. Temperature Setup and Stabilization: Set the temperature on PID controller and the fluid is heated to a preset temperature and temperature is stabilized. 
2. Specimen Preparation and Submersion: Mount the test specimen into the free shrink holder. Submerge them together into the liquid bath.
3. Time Monitoring and Completion: The timer starts to count down and when the test time is reached, an alarm will beep, signaling the end of the test.
4. Test Conclusion: Carefully remove the test specimen from the liquid bath. Press the Stop button on the tester to mark the conclusion of the test.
5. Shrinkage Measurement and Assessment: Treat test specimen in ambient environment and Measure the linear shrinkage of the specimen.

Calculation

To calculate the unrestrained linear shrinkage percentage using the given formula: 
Unrestrained Linear Shrinkage (%) = [(Lo - Lf) / Lo] x 100
Where:
Lo = Initial length (100 mm)
Lf = Length of the side after shrinkin

Technical Features 

1. Precise P.I.D. temperature control
2. High-precision timer
3. Alarm capability
4. Consistent fluid medium heating
5. Inclusion of a standard square metal clamp and a free shrink holder
6. Equipped with an oil bath cover

Standard

ASTM D2732 

Main Parameters 

Sample Size ≤160 mm x 160 mm
Temperature Range Ambient ~ 200°C
Accuracy ±0.3°C
Dimension 37*44*28 LWH cm
Power Supply 220V 50Hz