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General Ultracapacitor Information on 2008-12-10
- Capacitors, formerly known as “condensers,” are devices that store electric energy and release it needed.
- Capacitors can release a lot of power at once, but are poor at storing energy.
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- - They consist of two conducting plates (usually made of metals that are capable of being charged) and a thin dielectric (insulating material) as a separator. The plates are charged by a power source and, when the power is needed, they can send out their entire charge almost instantaneously. The amount of capacitance that can be achieved is directly proportional to the area of the plates, and inversely proportional to the distance between the plates.
  - Unlike batteries that have high energy capacity and low power, ultracapacitors (electrochemical capacitors or supercapacitors) can deliver high power in short bursts.
  - ultracapacitors can improve battery life by handling peak current output.
  - Ultracapacitors can be thought of as the bridge between traditional capacitors and batteries, because they have more power than batteries, but also more energy storage than capacitors. An ultracapacitor does not store energy between two plates like a traditional capacitor. It stores energy within an electrochemical double-layer that forms at the electrode/electrolyte interface as shown in the figure below.
SolRayo's Ultracapacitor Research on 2008-12-10
- We have developed a new method of fabricating ultracapacitors. We utilize less expensive carbon cloths or papers as our electrode backing material. We then coat these materials with nanoparticles that are able to improve the performance at a lower cost.
- Results for two nanoparticle-coated backing materials are shown by the blue and green squares in the figure below. We see that our materials have better energy storage and power delivery compared to typical ultracapacitors (electrochemical capacitors).
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- - Ultracapacitors can provide one to two orders of magnitude more charge/discharge cycles than rechargeable batteries. The plot below shows the performance of one of our electrochemical capacitors over 3 million cycles.
  - By using different backing materials, particle sizes, coating processes and differing electrolytes we can tailor performance of these electrochemical capacitors for specific application needs.
"Elements of Chemistry: Polymers and Plastics" on 2008-12-04
About plasticizers on 2008-12-04
- A plasticiser is a substance which when added to a material, usually a plastic,
  makes it flexible, resilient and easier to handle.
- Today, modern plasticisers are manmade organic chemicals; the majority of which
  are esters, such as adipates and phthalates.
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- - Importantly, they are not just additives (like pigments or fillers). They are
    major components that determine the physical properties of polymer products.
  - They are colourless, odourless liquids produced by a simple chemical
    reaction, whereby molecules of water are eliminated from commercially produced
    petrochemical products.
  - The most commonly used plasticisers are phthalates.
  - Predominantly, phthalates are used in the plastics industry to soften the
    popular plastic PVC. This is used to make a diverse range of cost effective
    products with various levels of technical performance suited to a wide range of
    applications. Many of these PVC products we use everyday but tend to take for
    granted. They include everything from lifesaving medical devices such as medical
    tubing and blood bags, to footwear, electrical cables; packaging, stationery,
    and toys.
Copolymerization on 2008-12-04
- The major practical problem, however, is that homopolymers
  blend together with difficulty and even where blends are possible, as in some
  thermoplastics, phase separation can occur readily.
  
  This problem is often overcome by polymerizing a mixture of
  monomers, a process known as copolymerization.
- It gives a much greater range of structures than is possible by mixing
  homopolymers because of the possibility of branching, structural isomerism
  within a single monomer, and the way in which the different repeat units can be
  added together.
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- - suppose that two monomers, A and B, are copolymerized. The chain could start
    with either a molecule of A or a molecule of B, and at each successive addition
    there are always two possibilities as to which monomer molecule will be
    attached. As shown in Table 7, the number of possible
    chain structures grows rapidly as n increases. Since the number of
    possible structures is proportional to 2ⁿ, it is easy to see
    that even for low degrees of polymerization the number of possible copolymers is
    very large indeed. Some of these molecules are identical however
  - Table 7 shows that the composition varies from chains
    of only monomer A (homopolymer A) to chains containing only monomer B
    (homopolymer B).
  - In many of the structures no regularity can be detected,
    although there will be short sequences of one type of unit, and the copolymer
    can be regarded as completely random; such copolymers are usually said to be
    ideal copolymers. These possible copolymer structures are shown
    schematically in Table 7.
  - It can be shown that the rate of change of monomer
    concentration in any copolymerization is given by the equation
    
    where [M₁] and [M₂] are the
    concentrations of monomers 1 and 2 at any instant and r₁ and
    r₂., are reactivity ratios. The reactivity ratios represent
    the rate at which one type of growing chain end adds on to a monomer of the same
    structure relative to the rate at which it adds on to the alternative monomer.
    The copolymer equation can be used to predict chain structure in the
    three different ways, already mentioned.
  - An ideal copolymer will tend to form when each type of
    chain end shows an equal preference for adding on to either monomer. In this
    case,
    
    and the copolymer equation becomes
    
    Hence composition depends on the relative amounts of
    monomer present at any time and the relative reactivities of the two
    monomers.
  - Step growth copolymerizations produce ideal (random) copolymers since in this
    special case r ₁ = r ₂ = 1.
  - The main reason for copolymerizing different monomers is to adjust the physical
    properties of a given homopolymer to meet a specific demand. SBR elastomer, for
    example (Table 1), based on 24 wt%
    styrene monomer shows better mechanical properties and better resistance to
    degradation than polybutadiene alone
  - A second reason for copolymerization is to enhance the chemical reactivity of a
    polymer, particularly to aid crosslinking. Conventional vulcanization in rubbers
    is brought about by forming sulphur crosslinks at or near double bonds in the
    chain
  - To show the dramatic effect of copolymer structure on
    physical properties, consider the change from random SBR copolymer to a block
    copolymer of exactly the same chemical composition but where the styrene and
    butadiene parts are effectively homopolymer chains linked at two points:
    
    The material behaves like a vulcanized butadiene rubber
    without the need for chemical crosslinking since the styrene chains segregate
    together to form small islands or domains within the structure. Such so-called
    thermoplastic elastomers (TPEs) today form an important growth area for
    new polymers because of the process savings in manufacture that can be achieved
    with their use.
Effects of Temperature on Polymers on 2008-12-04
- Many polymers have a mixture of ordered (crystalline) regions and random
  (amorphous) regions. In the glassy state the tangled chains in the
  amorphous region are frozen so movement of chains is not possible. The
  polymer is brittle.
- If the glassy material is heated, the chains reach a temperature at which they
  can move. This temperature is called the glass transition temperature
  T_g. Above this temperature the polymer is flexible.
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- - The glass transition temperature of a
    polymer can be changed by two different ways:
    
    Copolymerisation. Ethene can be
    polymerised with propene to give a new polymer with different properties.
    
    Plasticisers. PVC is quite
    brittle. Its T_g can be lowered, making it less brittle, by
    introducing a substance between the polymer chains, allowing the chains to slide
    over each other more easily. Such a substance is called a plasticiser.
Turning Plastics Back to Oil on 2008-12-04
- Key to GRC's process is a machine that uses 1200 different frequencies within
  the microwave range, which act on specific hydrocarbon materials. As the
  material is zapped at the appropriate wavelength, part of the hydrocarbons that
  make up the plastic and rubber in the material are broken down into diesel oil
  and combustible gas.
- "Anything that has a hydrocarbon base will be affected by our process," says
  Jerry Meddick, director of business development at GRC, based in New Jersey. "We
  release those hydrocarbon molecules from the material and it then becomes gas
  and oil."
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- - Whatever does not have a hydrocarbon base is left behind, minus any water it
    contained as this gets evaporated in the microwave.
  - Take a piece of copper wiring," says Meddick. "It is encased in plastic - a kind
    of hydrocarbon material. We release all the hydrocarbons, which strips the
    casing off the wire." Not only does the process produce fuel in the form of oil
    and gas, it also makes it easier to extract the copper wire for recycling.
  - Autofluff is the stuff that is left over after a car has been shredded and the
    steel extracted. It contains plastics, rubber, wood, paper, fabrics, glass,
    sand, dirt, and various bits of metal. GRC says its Hawk-10 can extract enough
    oil and gas from the left-over fluff to run the Hawk-10 itself and a number of
    other machines used by Gershow.
  - Because it makes extracting reusable metal more efficient and evaporates water
    from autofluff, the Hawk-10 should also reduce the amount of end material that
    needs to be deposited in landfill sites.
On oil and plastic on 2008-12-04
- Manufacturers take simple hydrocarbons from whatever source material they're
  using -- commonly crude oil, but also natural gas, corn, and other biomass --
  and turn them into polymers
- In the case of crude oil, they do this by heating it to more than 750 degrees
  Fahrenheit, then separating its components. The polymers usually travel onward
  in life in the form of pellets, ending up at one plastic factory or another to
  be molded into familiar shapes
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- - Polyethylene (HDPE
    or LDPE) is the soft one you likely encounter most, in milk jugs, shampoo
    bottles, plastic bags, and so forth. Polystyrene (PS) is
    the hard plastic that makes casings for computers and other appliances
  - call Styrofoam. Polypropylene (PP) is used in dishwasher-safe containers
  - You'll often find polyethylene terephthalate (PET) in soda bottles, and it is
    sometimes recycled into fleece, upholstery fabrics, and other useful materials.
    And then of course there's polyvinyl
    chloride (PVC)
  - about 4 percent of the world's annual oil production of some 84.5 million
    barrels per day is used as feedstock for plastic, and another 4 percent or so
    provides the energy to transform the feedstock into handy plastic.
  - drilling. Recycling, however, does cut into energy use. According to the U.S.
    EPA, manufacturing new plastic from recycled plastic requires two-thirds of the
    energy used in virgin plastic manufacture. I have more numbers, too: one ton of
    recycled plastic saves 685 gallons of oil.
How are Plastic Bottles Made ? A Start to Finish Process on 2008-12-04
How Is Nylon Made? on 2008-12-04
- nylon was used to make parachutes, clothes, military uniforms, tires,
  machine parts and other necessary items
- Nylon is made through a complex chemical reaction known as ring opening polymerization. In
  this reaction, a molecule with a ring shape such as hydrocarbons found in
  petroleum are submitted to various types of acids and bases. The ensuing
  chemical reactions cause the ring-shape molecular structure to flatten and
  lengthen. These molecules are caused to connect with one another to form
  molecular chains by being heated well above 600 degrees Fahrenheit. When done,
  what you have is a liquid with a high surface tension. If it cools down it will
  harden into a solid useless mass, so while it's still a liquid it is extruded
  through a hole with a diameter slightly greater than that of a human hair.
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- - There is one problem, however, with this is process called hydrolysis. It's a
    chemical reaction during which the oxygen and hydrogen molecules in nylon's
    molecular chain can be broken away from the chain to produce water. This is the
    primary means by which nylon decays. It does not happen over time, but is
    instead a reaction to contact with certain caustic materials such as sulfuric or
    hydrochloric acid

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Chem 109H Fall08

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This is a group for members of Chemistry 109H: Honors section of General Chemistry at the Univ. of Wisconsin - Madison. Instructor: J. Moore.

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