This is very interesting as it adds a whole additional class of superior plastics to our tool kit. These inverse vulcanized products form up at less that 185 celsius and produce superior properties. Considering how effective plastics have been, it is not hard to imagine a bright future here as well.
We have plenty of sulfur and we have ample oil as well now that the oil industry is close to been phased out of the fuel business. Their major market then becomes plastics.
The major market for sulfur has been for soil fertilization for a particular class of soils. This is better supplied by a mineralized form of sulfur which releases the sulfur through weathering.
.
Plastics of the Future May Be Made From Sulfur, Not Oil, Putting Waste to Good Use
What has chemistry ever done for me, you might ask? Just as
Dustin Hoffman was told by one of his would-be mentors in The Graduate,
one answer is plastics—one of the greatest chemical innovations of the
20th century.
Most plastic items are made of chemicals such as polyethylene (PET),
polypropylene (PP), polyurethane, or polyvinylchloride (PVC) which are
all derived from oil. These monomers are obtained industrially from the
fractional distillation of crude oil, and polymerized in great
quantities with catalysts in a process developed in the 1950s and 1960s.
Chemists Karl Ziegler and Giulio Natta shared the 1963 Nobel Prize in Chemistry for their titanium catalyst process, which for cost-effectiveness has yet to be bettered.
So the industrial feedstocks and methods of manufacturing plastics
have not changed significantly for more than 60 years. But the situation
has: oil is harder to come by and (usually) more expensive, and
environmental pressures are growing. If we want to keep plastics, we
will need to find new ways of making them. [ this is not particularly true and the price of the oil feed-stock is now likely to become dirt cheap. The more serious problem is making the product biodegradable. - arclein ]
Oil is harder to
come by and (usually) more expensive, and environmental pressures are
growing. If we want to keep plastics, we will need to find new ways of
making them.
Both an important mineral for health
as a solid but poisonous as a gas, sulfur usually conjures up vivid
images of fire, volcanoes and, through its archaic name brimstone, even
hell itself. But in fact sulfur is a waste product from many industrial
processes and could be an alternative to oil from which to manufacture
plastics.
An important
mineral for health as a solid but poisonous as a gas, sulfur usually
conjures up vivid images of fire, volcanoes and, through its archaic
name brimstone, even hell itself.
Under the right conditions, initially discovered by Jeffrey Pyun,
sulfur can change from its usual ring-like chemical structure and
instead form into long chains. These chains of sulfur can be joined
together to create a solid plastic or rubber using other organic
molecules to link them together. This process is dubbed inverse vulcanization, as it is the opposite of the vulcanization process applied to carbon to make rubber.
Patented by Charles Goodyear in 1844,
the vulcanization process joins long chains of carbon molecules using
sulfur, transforming liquid oil into solid rubber. So while rubber is
mostly carbon with a small amount of sulfur, conversely sulfur-based
plastics are mostly sulfur with a small amount of carbon. If we replace
most plastics made with oil with plastics made with sulfur it would
reduce demand for oil and put to use huge amounts of waste sulfur at the
same time—the pyramids of sulfur pictured above are byproducts of the
Alberta tar sands processing.
Our research
has examined how to change the way sulfur polymers act so as to make
them suitable for different uses. For example, we can change the
properties and proportion of carbon depending on what is required—hard
plastics contain more carbon molecules, soft plastics fewer. We can also
add nanoparticles to the mix that have the properties we want the
plastic to have, as they donate their characteristics to the end plastic
result.
Oil companies already spend billions of dollars removing sulfurous
compounds from petroleum every year to meet environmental regulations,
as sulfur in the air forms sulfuric and nitric acid, which falls as
damaging acid rain. And as the oil industry turns to extracting oil from
sulfur-rich tar sands, the amount of waste sulfur increases hugely.
The processes developed by ourselves and others have shown that
inverse-vulcanization polymers are not just viable but they can be
customized to suit a range of applications, simply by heating melted
sulfur and organic molecules at 185 degrees Celsius for 8–10 minutes
without the need for a catalyst. Investigation into how this would work
on a large scale has shown even lower temperatures can suffice.
In terms of customizable physical properties, the polymers can be
molded into a variety of shapes, and astonishing detail is possible. By
varying the organic content, the polymers can produce hard, glass-like
plastics, or tacky, malleable substances which have potential as
adhesives. This physical tuneability has led to their use even as a
cathode material for a new generation of lithium-sulfur batteries.
Sulfur polymers also reveal remarkable optical properties, assuming a
native transparent, ruby-red color. This could be used for infrared
lenses and/or optical filters. At this early stage, scientists are just scratching the surface of what could be possible.
Sulfur-polymeric materials are very much in their infancy. But if you
consider the extent and speed of the development of plastics over the
last 60 years, these materials might just offer a breakthrough in
reducing consumption of fossil fuels and put us on course towards a
responsible energy future. And who knows? There might be many more
amazing properties to discover along the way.
No comments:
Post a Comment