"Calorimetry on thin film samples at ultra high scanning rates: gaining insight into ultrafast processing of polymer and
|Fellow||Dipl.-Phys. Evgeny Zhuravlev|
|Foreseen duration||36 months|
|Ministering Institut||University of Rostock, Institute of Physics, Polymer Physics (Prof. Schick)|
|Project Goal||Recently developed calorimetric techniques based on submicron membranes allow the investigation of kinetic and thermodynamic features of structure formation in thin films or in very small (below µg) samples. The short response time of the calorimeter allows the formation of far from equilibrium structures with quenching rates of the order of µsec/K, a performance at present unique in Europe to our best knowledge. Crystallization processes may also be followed at millisecond time scale. Since most nanomaterials are in far from equilibrium thermodynamic states due to their synthesis conditions, this new technique allows to study complex nanostructure formation under processing relevant conditions. E.g. heating rates applied during ultrafast conventional or microwave heating can be mimicked. The microstructure formation and evolution in ultrathin polymer ceramic and polymer metal films is of particular interest with respect to the end properties of the composite films. Steric effects exerted by the polymer matrix control the size and volume distribution of embedded particles. Very narrow size distributions may be achieved using modified sol gel procedures.|
The thickness and cooling rate dependence of the glass transition, melting,
crystallization, chemical reactions, etc. will be investigated. New insight in these
processes can be revealed from heat of fusion and complex heat capacity of nanometer
thick films, which can be measured as function of temperature or time. The
experimental timescales are coming close to those available for the computer
simulation of polymer crystallization allowing direct interaction of theory and
experiment in the field of crystallization in thin polymer films. The work will be
performed in close collaboration with the groups at the Institute of Physics.
Applications are foreseen in photocatalysis, optical coatings, sensors, etc. The
project will be hosted by the Institute of Physics, Polymer Physics Group.
A new method was developed for online heat capacity measurements during temperature
scan of materials within wide range of controlled scanning rates, witch were never
covered before. Combination of conventional DSC technique, single sensor ultra-fast
and differential fast scanning techniques covers now a temperature scanning rate
range from 0.001 K/s to 106 K/s.
These three techniques were used for investigation of solidification kinetics of metal microparticles and study of reorganization processes in polypropylene with different additives (nucleating agents).
A large number of experiments were performed on Sn and alloy particles (Dr. Y.L. Gao, Shanghai University) of size from 10 nm to 500 µm. It was shown, that particles do not reveal expected shift of crystallization temperature with increasing cooling rate and reducing particle size. In the range from 10-2…105 K/s crystallization temperature changes step-like and description needs a better understanding of the nucleation mechanisms in the sample.
First experiments on the formation of quasi crystals were conducted together with Carmen Mihoc, another Marie Curie EST fellow from ADVATEC project. With introduction of the new high temperature sensor end of 2008 these experiments will be continued.
The new technique was also used to study the influence of different nucleating agents on melting and crystallization kinetics of isotactic polypropylene (iPP) (Marilena Pezzuto, ICTP, Pozzuoli, Italy, H. Kothe, DKI Darmstadt).
|Papers in international peer reviewed conferences,||
“Calorimetric measurements of undercooling in single micron sized SnAgCu particles in
a wide range of cooling rates”, Y.L. Gao, E. Zhuravlev, C.D. Zou, B. Yang, Q.J.
Zhai, C. Schick , Thermochimica Acta, in press.
Several posters on Differential Fast Scanning Calorimetry technique and its application for study of melting and solidification kinetics of metals and polymers were presented on following meetings:
|Talks on Conferences, Participation in workshops, summer schools, study visits and tutorials,
Two talks on the new calorimetric technique and its application for study of polymers
and metallic particles solidification were given on NATAS 36th meeting and RQ13
conference in Dresden.
On the 36th NATAS conference a Graduate Student Travel Award was received for the lecture “Differential Fast Scanning Calorimeter”.
|Publications||“Calorimetric measurements of undercooling in single micron sized SnAgCu particles in a wide range of cooling rates”, Y.L. Gao, E. Zhuravlev, C.D. Zou, B. Yang, Q.J. Zhai, C. Schick , Thermochimica Acta, in press (11.12.2008).|
|Using Devics and Instruments||
GC – Mass spectroscope,
Differential scanning calorimeter (DSC),