Week Nine: Final Film Testing and Project Completion

During week 9, the final puncture testing of the polymer films was conducted, and work was done to create a final report, presentation, and research poster. As noted in the Week 8 blog, the homemade puncture testing did not originally function properly. However, before resorting to a tensile test on the Angstrom machine, the group utilized a larger water bottle in the original puncture test. The larger water bottle had a volume of 1 gallon (3.78 liters). See the image below for the puncture test device.

 

Puncture Test Device

As in Week 8, the film was secured to a lidded plastic cup with tape, and the puncture test apparatus was situated above the film. Before beginning the test, the testing apparatus itself was weighed using a balance. Then, water was gradually poured into a hole at the top of the large water bottle, until the film eventually ruptured. Then, the volume of the water was measured, and the density of water (1 g/mL) was used to calculate the mass of water required to puncture the film. The mass of the water was added to the mass of the testing device, and this combined mass was multiplied by the acceleration due to gravity (9.81 m/s^2) to determine the force needed to rupture the films in Newtons. The results of the puncture test are shown below for the 100% PLA films, 50% starch films and 60% starch films when wet and dry.

Puncture Test Results
Trial	Puncture Force (N)	Displacement (cm)
Polyethylene Film	5.16	1.91
100% PLA Film	21.4	1.11
50% Starch Film	7.51	0.476
60% Starch Film - Wet	7.12	0.635
60% Starch Film - Dry	6.63	0.635

 

Puncture Test Pictures

Puncture Test Analysis Graph

After gathering the testing results, a cost analysis of low-density polyethylene, 100% PLA, and 60% starch films was conducted. Based on material costs alone, the PLA film cost $0.0368 the starch films cost $0.0280 and the polyethylene films cost $0.0137. Despite the higher price of the starch films compared to polyethylene films, the 60% starch films would nonetheless result in much lower environmental costs than the polyethylene films. The starch films consisted of completely renewable, bio-based resources and were readily biodegradable, as opposed to polyethylene films.

After gathering results and analyzing data, a final report was compiled. See the Final Report page for more details. Also, a research poster and presentation were prepared. See the research poster image below.

Research Poster