1 |
A comparison of porous polymers used in collecting organic volatiles in foodsBoyko, Alayne Linda 01 July 1975 (has links)
Porapak Q, Chromosorb 102, and Tenax GC, three porous
polymers commonly used as adsorbents in headspace analyses were
investigated. The retention times of various low-boiling compounds
relative to water were measured on the collection columns to determine
which compounds would be lost during the water removal step
employed after sampling aqueous materials. Compounds eluted
fastest from Tenax GC precolumns and slowest from Porapak Q,
with retention times on Chromosorb 102 generally intermediate.
Thus, loss of low-boiling compounds relative to water was greatest
on Tenax GC and limited the use of this polymer for quantitative
study of samples containing low-boiling volatile compounds. The
residual water in Porapak Q precolumns employed in the usual
procedure for collection of volatile materials by entrainment from
aqueous systems, could be completely eluted in 15 min with a N₂ purge of 30 ml/min at 55°C. without appreciable loss of collected
organic compounds.
Retention times of high-boiling organic compounds were determined
on the precolumns, and those containing Tenax GC had shorter
times than Chromosorb 102 or Porapak Q. Under conditions employed
for unloading trapped compounds from precolumns, fewer compounds
remained on Tenax GC precolumns. Thus, Tenax GC appeared to be
the trapping polymer of choice in investigations involving high-boiling
compounds. Back flushing of Porapak Q, Chromosorb 102,
and Tenax GC precolumns during unloading was essential in order
to recover the trapped organics within the time allotted for unloading
at 135°C. At 280°C back flushing on Tenax GC was not necessary
to insure unloading since retention times were well within the
unloading period.
The recovery of n-undecane from the precolumns after
simulated water removal conditions was found to be 98.5% for
Tenax GC, 99.5% for Porapak Q, and 100.0% for Chromosorb 102. / Graduation date: 1976
|
2 |
The negative thermal expasion along the chain direction for polymer crystals.January 1980 (has links)
by Wong Sai-peng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1980. / Includes bibliographical references (leaves 144-145).
|
3 |
Structure and properties of dimethacrylate polymersSimon, George Philip. January 1986 (has links) (PDF)
Bibliography: leaves 194-217.
|
4 |
Investigating hydrophilic channels in polymer composites using atomic force microscopyCummins, Matthew David. January 2007 (has links) (PDF)
Thesis (M.Eng.)--University of Louisville, 2007. / Title and description from thesis home page (viewed December 14, 2007). Department of Chemical Engineering. "December 2007." Includes bibliographical references (p. 58).
|
5 |
Surface dynamics at the polymer-air interface of water-plasma-treated polydiene films /Grunzinger, Stephen J., January 2002 (has links)
Thesis (Ph. D.)--Lehigh University, 2002. / Includes bibliographical references and vita.
|
6 |
Nonequilibrium behavior of polymeric network glasses /Tant, Martin Ray, January 1979 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University. / Vita. Abstract. Includes bibliographical references (leaves 125-127). Also available via the Internet.
|
7 |
Rod-climbing in molten polymersVu, Thi Khanh Phuong January 1976 (has links)
No description available.
|
8 |
The morphology of fibrillar polyolefin crystals.Wikjord, Alfred George. January 1968 (has links)
No description available.
|
9 |
The emulsion polymerization of alkylbutadienes.Aikin, Archibald McKinlay. January 1949 (has links)
The polymerization of alkylbutadienes has a long history, dating from Grenville William's experiments with isoprene, obtained from the destructive distillation of natural rubber (l). However no large scale production of polymers of butadienes was attempted until World War I, when the Germans manufactured over 2300 tons of polydimethylbutadiene. Until then the natural sources of rubber yielded adequate supplies for world needs. Some research was continued in the field of synthetic rubber andby 1939 the Germans, and later the Western Allies, were able to produce large quantities of synthetic elastomers (the name given to high polymers that possess rubber-like properties). A copolymer of butadiene and styrene, called Buna-S or GR-S, wasconsidered to be the best general purpose synthetic elastomer and this copolymer is produced on a large scale on this continent. Much research has been done on this material but the pure polymers, such as polybutadiene and polyisoprene, have not been investigated as thoroughly since they have failed to show promising properties. As copolymers have the extra variable of compositional heterogeneity, it is thought that the study of pure polymers may lead to an easier and better understanding of the problems involved in obtaining elastomers of the desired properties.[...]
|
10 |
Investigation of surface damage resulting from static charging of moulded plastic componentsTaylor, Paul James January 1999 (has links)
Static Charging or Contact Electrification occurs on the separation from intimate contact of materials of dissimilar properties. The amount of charge transferred is dependent on, amongst other things, the contact potential difference between the materials. While a great deal of work has been performed in the past investigating contact electrification, variability in contacts from sample to sample has led to difficulty in providing a fundamental understanding of the process. The investigation here is concerned with surface damage to a plastic component (a spectacle lens), which results from contact electrification. The component in question is cast between two crown glass moulds. After curing, the moulds adhere strongly to the plastic requiring significant leverage to separate them. When separation occurs in the dark, a flash of light is often seen. / Thesis (PhD)--University of South Australia, 1999
|
Page generated in 0.0566 seconds