Polymer-filler interactions chain segments

Fmthermore, Nowicki [34] carried out calculations on the chain entropy in the presence of nanoparticles using the MC method. He has shown that the loss in the confoimational entropy is associated with spatial rearrangement of molecular segments caused by the adsorption process. The stronger the polymer-filler interaction is, the larger entropy loss can occur. As the particle diameter drops below the radius of gjTation of the chain, the entropy perturbation starts to be more localized within the coil. Thus, it can be concluded that the nano-... 

There are three types of chains or chain segments which may be involved in filler-polymer interactions ... 

In view of the experimental findings on filler-matrix interactions and their effects on conformations of polymer chains, it is suggested that non-covalent filler-matrix interactions and the resulting increases of the exposure ofless polar groups and chains segments at the interfaces reduce the polarity of the droplets, which in turn reduces the interfacial tension. 

Positron annihilation has been proven to be an effective tool to probe the interfacial characteristics of polymer nanocomposites. Zhang et al. used positron annihilation to study structures of melt-compounded HDPE/CaCOj nano-compositites in which nano-CaCOs fillers were treated with a coupling agent. A rapid decrease of free-volume concentration with increasing nano-CaCOs weight fraction was observed. An interfacial layer between the nano-CaCOs fillers and HDPE was also detected, which verified that die interactions between the nano-CaCOs and HDPE matrix indeed restricted the chain segmental motion and reduced the mobilization of polyethylene chains. 

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