PLA Application Biodegradable Mulch Sheets Presentation By Kelsey
PLA Application: Biodegradable Mulch Sheets Presentation By: Kelsey Westerkamp Article’s Authors: Yuya Tachibana, Takuya Maeda, Osamu Ito, Yasukatsu Maeda, and Masao Kunioka
Introduction ● Mulch Sheetsused in agriculture for high-value crops ■ Sweet Potatoes ■ Strawberries ■ Oranges ○ Benefits of a white mulch sheet: ■ reflected light speeds up growth ■ increases quality of fruit (sweeter) ■ labor decreases- less need for weeding and decreased presence of insects ○
Introduction (cont. ) 1. PLA: produced from biorenewable resources (corn) 2. Ecoflex®: poly(butylene adipate/terephtalate) chemical structure; made from oil-based compounds 3. Starch: a. must be modified to bond with PLA and have thermoplastic and moldable qualities b. most inexpensive and widely available biodegradable material
Three Biodegradable Materials a) PLA; b) Ecoflex; c) Modified Starch
Hypothesis “Due to the differences in biodegradability, the properties of the mulch sheets gradually change, and the changes in the water permeability have a positive effect on the mandarin orange growth. ”
Methods 1. Inflation Molding: a. inexpensive sheet-molding method used in agriculture b. creates a thin and wide sheet c. relies on a suitable melt viscosity (thickness) d. PLA and modified starch need Ecoflex to be incorporated for a successful molding process 2. UV-Vis Spectrometer: a. measures reflectance and transmittance of the sheet
Methods 3. Gas Permeation Measurement Apparatus: a. measures how much oxygen and other gases travel through the mulch sheet 4. Universal Testing Machine: a. measures mechanical properties of the sheet b. sheet cut into small pieces to be tested 5. IR Spectrometer: a. measures absorption and transmittance
Results Mandarin Orange Tree with and without a mulch sheet Moisture Regain: controlled with the mulch sheet (modified starch biodegrades first, leaving pores)
Results ** Pure PLA will not mold ** PLA with modified starch will not mold ** UV-Vis Spectrometer used to calculate transmittance and reflectance ** Most reflectance with the mulch sheet than without
Results ** The less thick the mulch sheet is, the quicker the modified starch degrades and more gases are permeated through the mulch sheet ** Brix degree (sweetness/sucrose content) increased w/ mulch sheet ** acidity of fruit increased w/ mulch sheet ** Color intensified w/ mulch sheet
Results p. F values measure of force with which soil particles can hold water ** MS--3, 7, 0 has consistent and higher p. F values compared to unmulched soil and the other ratio Temperature of the soil ** MS--3, 7, 0 made the soil the warmest because of the way it reflected sunlight
Results Tensile strength decreased greatly after 30 days, and some more after 90 days due to controlled degradation (varying degradation rates of components of mulch sheet)
Discussion ● White Mulch Film made with PLA/Ecoflex®/Modified Starch allowed reflectance of UV light to improve photosynthesis process ● Modified starch degraded first & pores in film made it more permeable for gases o gas permeability-regulated because of different degradation rates of the materials o pores also allowed more moisture to seep in for the plant
Discussion ● Improvements in photosynthesis → improved quality of oranges o o o Brix Degree increased Acidity increased Color of orange more intense ● Mulch film gradually decreased in tensile strength (biodegraded successfully)
Conclusion ● Hypothesis proven o the combination of PLA/Ecoflex/Modified Starch did improve quality of mandarin oranges ● Incentive to using this mulch sheet o o entirely biodegradable different components degrade at different rates to better plant growth ● Post-degradation product: CO 2 and H 2 O
- Slides: 15