Experimentation study of the degradation of polyoxymethylene. Application to the origin of the formaldehyde extended source in comets.

Details Experimentation study of the degradation of polyoxymethylene. Application to the origin of the formaldehyde extended source in comets. Experimentation study of the degradation of polyoxymethylene. Application to the origin of the formaldehyde extended source in comets.

Apr 2003

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003eaeja.....5080f&link_type=abstract

EGS - AGU - EUG Joint Assembly, Abstracts from the meeting held in Nice, France, 6 - 11 April 2003, abstract #5080

Physics

Scientific paper

The formaldehyde (H2CO) observed in cometary atmospheres presents a so-called “extended source”. It means that its distribution in comae cannot be explained by a direct sublimation from the nucleus, but rather by a production in the coma. The origin of this extended source is still an unsolved question. The polyoxymethylene [formaldehyde polymers: (-CH2-O-)n] is sometime evoked as a possible parent molecule for this extended source. This polymer in solid state on cometary grains could release gaseous formaldehyde through thermal and photolytic degradation. We have developed an experimental program in order to study the chemical reactions of degradation of solid polymers by UV irradiation and heating. It provides identification of the degradation products and the determination of the photodegradation quantum yields or the thermodegradation kinetics. Those fundamental data are then included into a model of the outer coma in order to interpret observations. It leads to a very good agreement with Giotto observations if we assume that the cometary grains are made of about 4% POM by mass. Moreover the obtained results have also shown that the thermal degradation of POM is the predominant process over photodegradation at 1 au from the sun. So far the thermodegradation kinetics were measured for a small range of temperature and for only one type of POM molecular structure. So the incertitude on the activation barrier and on the frequency factor was large. We will present the improvements of our experimental setup and the new study of the thermal degradation of POM, which permit us to extract more reliable data. The application of this new set of data to the cometary environment will be discussed.

Affiliated with

Also associated with

No associations

Rating

Experimentation study of the degradation of polyoxymethylene. Application to the origin of the formaldehyde extended source in comets. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Experimentation study of the degradation of polyoxymethylene. Application to the origin of the formaldehyde extended source in comets., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Experimentation study of the degradation of polyoxymethylene. Application to the origin of the formaldehyde extended source in comets. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-843095