Team:Stanford-Brown/Plastic
Plastic Folding
Testing and Applications
Why plastics?
Plastic is an extremely versatile material that can be used in a multitude of applications such as in medical devices, construction, prototyping, and much more. Currently, many common plastics require the use of petrochemicals to manufacture. To utilize the benefits and versatility of plastics in long term space travel and space colonies would require the importation of petrochemicals into space. With the limited volume and mass payloads of space travel, our team wanted to try to find an alternative to manufaturing plastics in space.
Our team looked to synthetic biology to find a solution to the manufacture of plastics in space to minimize the use of petrochemicals. This summer we wanted to engineer the bacteria E. Coli to produce two kinds of plastic: Polystyrene and P(3HB). The prospect of being able to send a sample of bacteria into a space station or colony and having that bacteria manufacture plastic is an exciting prospect for our team.
How does plastic fold?
Most plastics are long organic polymers with a high molecular weight. When these long chains of monomers are prestretched in their manufacturing they have a relatively high level of organization. When heated to their glass transition temperature, these prestretched plastics will contract in the dimention that they were prestreched. With the use of pigments, (and in our case, biopigments) we can select where and how the prestretched plastic contracts. By drawing these pigments on the plastic and using infrared light from the sun, we can make the plastic fold. This is because in a flat sheet of prestretched plastic, drawing a dark line on the plastic will allow that section of the plastic to heat up and contract faster than the rest of the plastic. Having the dark line only on one side of the plastic will cause the plastic to fold toward that side as seen in figure 1
By having plastics fold, we can quickly prototype new designs of self polding by simply printing on biopigments onto plastic sheets and applying infrared light to the plastic. These designs can range from simple cups and containers to complex solar sails and arrays.
Figure 3 Polystyrene joints adhered to a cardboard substrate
Figure 3 After heating joints with infrared lamp the plastic folded
Figure 2 Polystyrene sheet cut into a box pattern with black pigment on inner edges
Figure 3 Self-folded box after applying heat from infrared lamp
Figure 3 Before heating the plastics: Polystyrene (PS) and Polylactic Acid (PLA)
Figure 3 After heating the plastics evenly the plastics contracted in two dimensions
Figure 3 Printing pigment on sanded plastic sheets
Figure 3 Before heating polystyrene joints adhered to cardboard substrate
Figure 3 Heating causes the plastic to shrink and fold the cardboard
Figure 3 Simple pigment pattern on polystyrene sheet
Figure 3 Plastic sheet folding up to a more cup-like container
Figure 3 Using sunlight to heat and bend polystyrene