Polymer Lab

Topics: Materials science, Tensile strength, Polypropylene Pages: 4 (1013 words) Published: October 20, 2008
Materials and Manufacturing 2
Processing and testing of polypropylene

Part A. Injection molding of polypropylene samples for mechanical testing.


Injection molding is the most productive and popular polymer processing techniques. Almost 70% of all plastic parts are made using injection molding. Injection molding of plastics is a process similar to die casting of metals. Molten polymer is injected under pressure into a mold.


Put the plastic material (Polypropylene) in granular form into the hopper. Set the injection molding temperature: nozzle 1 240 °C, zone1 220 °C, zone 2 180 °C, zone 3 20 °C. Startup operations
Press the red emergency stop button and release it by rotating in the direction of arrow. Open and close protective grating.
Put position selector on control panel into “Manual operation” mode. Press the “STOP” button on the control panel for a moment. Press “START” button on the control panel.
Put position selector on control panel into “Semi automatic” mode. Close the mould by pushing “CLOSE MOULD” button on the control panel.

After each cycle open and close protective grating to make the next product. Overall make 5 moldings of samples for tensile and impact testing.

1. Mechanical testing of polypropylene samples.
Tensile testing of thermoplastics

Standards: AS 1145 (Australian standard), ASTM D 638 (US standard)

Testing equipment:
Universal testing machine Zwick Z010;
Electronic digital calliper Pro-max.

Measure and record the dimensions of the cross sections of the test specimen; Clamp up specimen in the crossheads of machine and run the test. Set distance between grips 100 mm

Perform five tensile tests.

Determine the mean and standard deviation of the samples tensile strength (maximum stress from stress-strain curve).
Impact testing of thermoplastics.

Standard ASTM D 256 (US standard), ISO 180 (International standard).

Testing equipment:...
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