I have a few questions, please help me answer them!
What are plasticisers? What other additives can be added to plastics? What are polymers? What are polymers made from and are they sustainable? Banning phthalates from children's toys is an example of the ALARA principle. Explain what this means? Plastics cause a lot of waste. Name 3 ways it can be dealt with. Draw a diagram to illustrate the process of polymerisation. Why are plasticers added to polymers? How do plasticisers work? Draw a diagram to illustrate your answer. What does toxicity mean? Phthalates use in yours is banned in the USA and Europe but not in furniture and packaging. Suggest why there is not a total ban?
Will be apperciated ALOT!
Thanks!
Plasticizers are added to some types of plastic, to make them more flexible. The most common example is Polyvinyl Chloride, which is quite hard an brittle in the pure state. Commonly, plasticizers such as Polyvinyl Acetate are added to achieve varying degrees of flexibility as desired. Most other common plastics such as ABS, polystyrene, polycarbonate, polyethylene, polypropylene, and others, do not have plasticizers mixed with them.* The plasticizer material is simply mixed with the plastic and forms a sort of "alloy", not unlike what happens when two different metals are mixed. The base polymer does not change chemically. Typically, a plasticizer works by fitting between the long chains of a polymer's molecules, and causes them to separate slightly. This reduces the strong attraction between polymer chains, and results in increased flexibility.
Over time, and especially with exposure to solvents, some of the plasticizer can be dissolved (or "leached") away, and the polymer will then become less flexible. A good example of this is seen with ordinary clear, flexible "vinyl" tubing. It was once common to use this tubing to carry gasoline (for example, to carry gasoline from the tank of a motorcycle to its carburetor). The result was that over time, the gasoline dissolved and removed much of the plasticizer, resulting in the tubing reverting back to nearly pure polyvinyl chloride and becoming very hard and brittle.
Dreading this exam. When I did my past papers a couple of weeks ago I was barely achieving half of the paper correctly without the pre-release. It feels rubbish. I hope the IIC will be simple, and the grade boundaries being traditionally low....
Impressive coursework mark, I got only 37 haha 270-50-48-96 = 76 which is a mid-B, you're looking at.. only needing 20 raw marks? That's if the paper was like it was in June 2010 though :P
hey guys, so nervous about tomorrow! All the stuff on here has really helped though, thank you Can anyone tell me what mark i need to get for an a*? My marks are:
on chem ive got 44/50 43/50 and 34/40 for course work biology i got 48/50,44/50 and 34/40 in physics i got 43/50 43/50 and 35/40
could you tell me what i need to get for each please
Kingberito123, Biology (270-48-44-90 = 88 UMS needed, roughly a very high A for B7) Physics (270-43-43-91 = 93 UMS needed, so going near a mid A* for P7)
hey guys, so nervous about tomorrow! All the stuff on here has really helped though, thank you Can anyone tell me what mark i need to get for an a*? My marks are:
123: 44.50 456: 47/50 cw: 35/40
Kid4, I'm nervous too :/ (270-44-47-91= 88 UMS needed for C7) So roughly a high A needed