We propose a simple friction model for isolated polymer chains on a solid substrate. The chains are pulled at constant velocity
by one end, the other end can be trapped on the solid substrate on localised sites. We focus on the energy dissipation due
to the traps. This simple model leads to nontrivial friction laws, depending on the velocity and the distance between traps.
Some refinements of the model such as the effect of thermal fluctuations are also reported.
Received 20 March 2000 相似文献
For the investigation of vulcanizates structure, new models have been developed relating the modulus of vulcanizates and the volume fraction of filler. The parameters of the models are the filler distribution and the properties of the shell surrounding the filler particles. Three functions of filler distribution have been assumed. Dynamic mechanical properties of a series of vulcanizates were tested and the parameters of the models were computed. The obtained data allows estimating the properties of the shell formed around filler particles in vulcanizates and to distinguish the functions of filler distribution. 相似文献
Secondary domain superstructures in correlated random block copolymers are considered theoretically using the concept of the
second order parameter related to fluctuations of the local mean block length. It is shown that the size of secondary domains,
, is much larger than the primary domain size, L: , while , where is a small parameter defining the composition asymmetry. Different secondary morphologies are characterized. It is also shown
that separation of the system in two macroscopic phases with different primary morphologies predicted earlier using the free
energy expansion up to ( is the usual order parameter related to local composition) is an artifact of this widely accepted theoretical model.
Received 15 July 1998 and Received in final form 18
January 1999 相似文献
Elastomeric proteins represent a very interesting subject of investigation, not only for their molecular mechanism(s) of elasticity, but also for their great potential as novel biomaterials. This review is intended to give an overview of the properties of the main elastic proteins, with particular focus on elastin and, at the same time, a report on the most recent acquisitions in the field of elastomeric biomaterials.
TEM image of poly(OrnGlyGlyOrnGly) after crosslinking reaction with GTA. The bar represents 100 nm. 相似文献