Scrap House

Scrap House: Built for the 2005 World Environment Day
http://www.scraphouse.org/home

Bacteria: Polystyrene Foam

Another species of bacterium, Pseudomonas putida, naturally found in soil, has been modified in a bioreactor to consume styrene. Actually, they remove the pollutants and converts the styrene into the plastic polymer PHA (polyhydroyalkanoates). PHA can be used as a biodegradable plastic in the use of eating utensils, and have a wide range of industrial and commercial uses such as medical implants or scaffolds for tissue engineering. The process starts by heating up styrene foam and converting it into styrene oil and then feed to the bacteria. PHA is heat, grease, and oil resistant and biodegrades in soil and water. But, if it is sent to a landfill, it will most-likely fossilize under the compressed layers of garbage and dirt.

Sources:

http://en.wikipedia.org/wiki/Biodegradable_plastics
http://en.wikipedia.org/wiki/Bioplastics

Alternative: Corn

Sorona is an alternative to petrochemicals by using corn sugar instead. It requires 40% less energy to produce than an equal amount petroleum-based Nylon. Also, producing Sorona reduces CO2 emissions up to 60% over an equal amount of petroleum-based Nylon. 

Sorona fibers begin accepting dye pigments below the boiling point of water, full depth of color is achieved at the boiling point compared to PET which is well above. The stress/strain ratio is much less compared to Nylon and PET, where the applied strain/total recovery ratio and the percent elongation/load g/den is much higher than Nylon and PET. 

All around it seems better, but what about the genetic manipulation of corn and the treatment of farmers? To learn more about that, see Rachel Silverberg's blog about corn at  www.cornbloat.wordpress.com.

Cold Drawing: Part 3

After the completion of spinning Nylon, the molecules are not aligned, making the Nylon yarn really thick. Cold drawing is the application of tension to allow the molecules to align, shrink the diameter, remove its elasticity, and increase its tensile strength. From the picture below, you can see the tension applied to the five wraps around the two pulleys that move in and out.

Spinning Nylon: Part 2

The diagram below shows DuPont's original process of spinning Nylon. The method seems more like an extrusion process rather than spinning. The molten Nylon is forced out of the stainless steel block through tiny holes and gravity carries the filaments down to a bobbin. This bobbin with the spooled Nylon will then go to the cold drawing process.

How Do You Make Nylon? Part 1

Making Nylon Salt

▪ Add 1 molal part of hexamethylene diamine [NH2(CH2)6NH2].
▪ Add 1 molal part of adipic acid [HOOC(CH2)4COOH].
▪ Stir in deionized water at 70 oC.
▪ Precipitate the nylon salt from solution.

Making Nylon Polymer

▪ Evaporate nylon salt solution to ~80% salt. Drop (feed) solution into autoclave.
▪ Add acetic acid (stabilizer) and TiO2 (delusterant) if needed.
▪ Set autoclave controls to 295 oC and 250 psi.
▪ At 250 oC instantaneous polymerization occurs resulting in a polymer of 15,000 to 18,000 desired molecular weight.
▪ Automatically the H2O is bled off to 0 psi over a 30 minute period.
▪ Hold autoclave at 0 psi for 30 minutes to "settle" molten polymer.
▪ Extrude (cast) nylon [as ribbon] over a roll sprayed with water.
▪ Cut nylon ribbon into chips.
▪ Blend batch with five other batches to obtain average uniformity (molecular weight).

What is recyclable?

1. PET (PETE), Polyethylene terephthalate: 2-liter soda bottles, cooking oil bottles, peanut butter jars

2. HDPE, High-density polyethylene: Milk jugs and detergent bottles

3. PVC, polyvinyl chloride: pipe, outdoor furniture, siding, flooring, shower curtains, clamshell packaging

4. LDPE, Low-density polyethylene: dry-cleaning bags, produce bags, trash can liners, food storage containers

5. PP, Polypropylene: bottle caps, drinking straws, yogurt containers

6. PS, Polystyrene: packing peanuts, cups, plastic tableware, meat trays, take-out food clamshell containers

7. OTHER: Any plastic other than 1 - 6, Tupperware and Nalgene bottles 

No specific number for Nylon!