Glass memory effects

Note Disposable vials are free of memory effects. Glass vials bear the additional advantage of showing how much sample is placed at which position in the vial. Afterwards, it is also possible whether the analyte decomposed during the measurement to yield some black residue. 

Shape-memory materials are those materials that return to a specific shape after being exposed to specific temperatures. In other words, these materials are able to remember their initial shape. This process of changing the shape of the material can be repeated several times. The shape-memory effect has been observed in different materials, such as metallic alloys, ceramics, glasses, polymers and gels. 

The above equations can also predict the celebrated memory effect of Kovacs (1964). The memory effect can be observed by quenching a glass former, such as B2O3, from equilibrium 583.2 K to a lower temperature, 498.7 K, and then aging the sample at this lower temperature long enough to bring its fictive temperature Tf down to some lower temperature. 

These are used on most commerdal process mass spectrometers. Often aim long capillary of 10-100 pm inner diameter is suffident to provide the necessary pressure drop. Deactivated fused siHca is the most common capillary material, since it is reasonably inert and does not exhibit significant memory effects with most sample streams. Heating the capillary further reduces memory effects and pluggage due to condensation. Capillaries can also be made of other materials such as stainless steel or nickel if silica is problematic. Molecular leaks (pinhole orifices) are sometimes used, either in conjunction with or in place of the capillary. Porous frits, either of sintered glass or metal, are sometimes used to avoid pluggage problems with a capillary or molecular leak, but these can often exhibit greater memory effects. 

Bellon L, Ciliberto S, I,aroche C (2002) Advanced memory effects in the aging of a polymer glass. Eur Phys J B 25 223-231... 

To define ic we recall the clasacal densiflcatitMi experimoit whoe a glass is formed under a pressure P and once having arrived suffidoitly far in the glassy domain, is depressurized. Due to the memory effect the final volume is... 

Figure 3.1 Various molecular structures of shape memory polymers (SMPs). A stable network and a reversible switching transition are the prerequisites for the polymers to show the shape memory effect (SME). The stable network can be molecule entanglement, chemical cross-hnking, crystaUization, and IPN the reversible switching transition can be the crystalUzation/melting transition, vitrification/glass transition, anisotropic/isotropic transition, reversible chemical cross-linking, and association/disassociation of supramolecular structures. Source [22] Reproduced with permission from Elsevier...

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