新托福閱讀背景知識匯總（四十五）

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polymer gels一種聚合凝膠

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.

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