03-08-2009, 04:02 PM
Cryogenic grinding, also referred to as freeze grinding, is the act of cooling or chilling a material and then reducing it into a small particle size. For example, thermoplastics are difficult to grind to small particle sizes at ambient temperatures because they soften, adhere in lumpy masses and clog screens. When chilled by dry ice, liquid carbon dioxide or liquid nitrogen, the thermoplastics can be finely ground to powders suitable for electrostatic spraying and other powder processes.[1] Cryogenic grinding of plant and animal tissue is a technique used by microbiologists. Samples that require extraction of nucleic acids must be kept at -80 ºC or lower during the entire extraction process.[1] For samples that are soft or flexible at room temperature, cryogenic grinding may be the only viable technique for processing sample
read this
http://cda-adc.ca/jcda/vol-72/issue-9/795.pdf
http://en.wikipediawiki/Cryogenic_grinding
