ISSN:
1432-0630
Keywords:
Positron annihilation
;
Polymers
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Abstract The decay time τl ofo-Ps by the electron pickoff process has been measured in polystyrene as a function of molecular weight. For samples below their glass transition temperature τl is essentially independent of $$\bar M_n $$ . In the low molecular weight region, $$\bar M_n〈 850$$ , τl increased with decreasing $$\bar M_n $$ in line with earlier theoretical predictions. The overall behaviour reflects closely the dependence of free volume on $$\bar M_n $$ . The effects of molecular motion on τl are examined and it is concluded that the decay time is insensitive to such motions in polystyrene below the melting point, in contrast to what is observed in polytetrafluoroethylene.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00936020
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