Polyvinyl Chloride History

13-year-old's solar project generates heat if not light

Who decided solar panels should be flat?

A seventh-grader from New York has worked out that solar panels arranged more like tree branches may capture more light than flat panels.

For real, kind of. Aidan Dwyer, 13, noticed that tree branch patterns are Fibonacci numbers, postulated that it had to do with photosynthesis, took some pretty involved measurements of an oak tree, built a PVC-pipe solar array in the same shape, built a flat solar panel, compared how much light each captured over time, and voila, he had an award-winning science experiment and a great-sounding theory: trees evolved with these patterns for good reason. He found that tree-shaped pattern is as much as 50 percent more efficient than the flat panel, depending on the time of year.

The seventh-grader's explanation was that the Fibonacci pattern keeps branches out of each others' shadows in full light and at the same time allows the tree to garner as much light as possible when some branches are in shadow and others in light.

Dwyer wrote up the results in an essay that includes details of a winter hike in the Catskills, the centuries-old history of humans noticing these patterns throughout nature (from shell structure to Galaxy shape), and a nice description of the way Fibonacci explained the numbers using the rabbit birthrate and Sanskrit poetry. The essay won the American Museum of Natural History Young Naturalist award.

Here's where the story takes an interesting turn. More than one scientist has poured cold water on Dwyer's theory, while others have cautioned not so fast. It's a good lesson in the importance of peer review before publishing. Just as tree branches are arranged the way they are for a reason, so are today's silicon solar cells.

And even if Dwyer's experiment holds up to scrutiny, there's a lot involved in making a successful solar module. After theory, proof of concept, peer review, and one or more back-to-the-drawing-boards, you still have cost of manufacturing and competition with other technologies.

History of PVC « www.rpetc.com

History of PVC

PVC was accidentally discovered at least twice in the 19th century, first in 1835 by Henri Victor Regnault and in 1872 by Eugen Baumann. On both occasions the polymer appeared as a white solid inside flasks of vinyl chloride that had been left exposed to sunlight. In the early 20th century the Russian chemist Ivan Ostromislensky and Fritz Klatte of the German chemical company Griesheim-Elektron both attempted to use PVC (polyvinyl chloride) in commercial products, but difficulties in processing the rigid, sometimes brittle polymer blocked their efforts. Waldo Semon and the B.F. Goodrich Company developed a method in 1926 to plasticize PVC by blending it with various additives. The result was a more flexible and more easily processed material that soon achieved widespread commercial use.

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