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托福阅读背景材料：聚合凝胶

2015-05-08 10:35:11来源：网络

　　托福阅读背景知识是考生托福阅读备考过程中必不可少的参考资料，托福阅读内容量大，取材丰富，话题面广，需要考生积累必要的背景知识。本文中新东方在线托福网为大家带来托福阅读背景材料：聚合凝胶，希望对大家托福备考有所帮助。更多精彩尽请关注新东方在线托福网!

　　托福阅读背景材料：polymer gels一种聚合凝胶

　　The following information was part of our display for the SET96 and SET98 Scientific Power to the People Exhibition, The Galleries, Bristol, 20th and 21st March 1998.

　　A POLYMER is a very long molecule rather like a very long piece of string.

　　The borax joins two molecules together to make a large network - rather like a flexible scaffolding. This is cross-linking.

　　This turns the fluid dissolved polymer into a GEL.

　　In oilwells water is pushed down to push oil up. If this breaks through to the production well bore, the well will just produce water. A solution is to block the rock pores with polymer gel to make the well produce oil again. These gels can be made from naturally occurring sugar-based polymers such as Guar and they can be cross-linked with Cobalt or Chromium.

　　Other everyday examples of polymer gels are to be found in non-drip emulsion paints, foods, car tyres and agrochemicals.

　　The polymer that we are using is POLYVINYL ALCOHOL and we are joining the strands together with BORAX. This gel, when coloured, is sold in toyshops as SLIME.


　　查看全部：新托福阅读背景材料大全

　　专题推荐：2015年托福真题机经及答案解析


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