Xerogel | Clipmarks


	Xerogel

azanhk

10-9-2008 5:21 AM

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azanhk says:

I need to understand what are xerogel and aerogel.

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<div style="margin: 12px 0px; font-family: arial; color: #333333; background: #ffffff; border: solid 4px #e5e5e5; width: 100%; clear: left;"><div class="CM_CTB_Content_Wrap" style="margin: 0px; padding: 0px;background-color: #ffffff;"><div style="border-bottom: solid 1px #dcdcdc; white-space: nowrap; margin-bottom: 8px; background-color: #eeeeee ;background-image: url(http://clipmarks.com/images/source-bg.gif); background-repeat: repeat-x; height: 24px; line-height: 24px; vertical-align: middle; padding-bottom: 4px; color: #666666; font-size: 10px;" ><a href="http://clipmarks.com/clip-to-blog/" title="see clips that are hot right now"><img src="http://content.clipmarks.com/blog_embed/8aafeafe-1af5-4743-9d22-e2d038e2a55c/81BD875F-2CDD-4FD6-8775-65DE3D21E711/" alt="" width="19" height="19" border="0" style="vertical-align: middle; margin: 0px 4px; display: inline; border: none; float:none;" /></a>clipped from <a title="http://www.answers.com/XEROGEL" href="http://www.answers.com/XEROGEL" style="font-size: 11px;">www.answers.com</a></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.answers.com/XEROGEL"><DIV class="DsAndEntryName">
<A class="tabTitle" href="http://www.answers.com/library/Wikipedia-cid-5534407"><SPAN class="tabTitle">Wikipedia:</SPAN></A>
<H1>xerogel</H1>
</DIV></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.answers.com/XEROGEL"><P>A <B>xerogel</B> ['z<FONT face="Times New Roman"><SMALL>I</SMALL></FONT>rə,d<SPAN class="IPA" title="Pronunciation in IPA">ʒ</SPAN>εl] is a solid formed from a <A  class="ilnk" href="http://www.answers.com/topic/gel">gel</A> by drying with unhindered shrinkage. <A  class="ilnk" href="http://www.answers.com/topic/gelatin">Gelatin</A> is one example. Xerogel usually retains high porosity (25%) and enormous surface area (150-900
m<SUP>2</SUP>/g), along with very small <A  class="ilnk" href="http://www.answers.com/topic/sebaceous-gland">pore</A> size (1-10 nm). When <A  class="ilnk" href="http://www.answers.com/topic/solvent">solvent</A> removal occurs under hypercritical (<A  class="ilnk" href="http://www.answers.com/topic/supercritical-fluid">supercritical</A>)
conditions, the network does not shrink and a highly porous, low-density material known as an <I><A  class="ilnk" href="http://www.answers.com/topic/aerogel">aerogel</A></I> is produced. Heat treatment of a xerogel at elevated temperature produces viscous <A  class="ilnk" href="http://www.answers.com/topic/sintering">sintering</A> (shrinkage of the xerogel due to a small amount of viscous flow) and effectively transforms the
porous gel into a dense <A  class="ilnk" href="http://www.answers.com/topic/glass">glass</A>.</P></blockquote></div><div style="margin: 0px 6px 6px 4px;"><table style="font-size: 11px;border-spacing: 0px;padding: 0px;" cellpadding="0" cellspacing="0" width="100%"><tr><td style="background:transparent;border-width:0px;padding:0px;">&nbsp;</td><td align="right" style="background:transparent;border-width:0px;padding:0px;width:107px" width="107"><a href="http://clipmarks.com/share/81BD875F-2CDD-4FD6-8775-65DE3D21E711/blog/" title="blog or email this clip"><img src="http://content9.clipmarks.com/images/c2b-foot.png" border="0" alt="blog it" width="107" height="17" style="border-width:0px;padding:0px;margin:0px;" /></a></td></tr></table></div></div>

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