Mediating the slow dynamics of polyacrylates by small molecule-bridged hydrogen bonds

This report studied the changes in the slow dynamics of polyacrylate by adding a hindered phenol (CA) capable of forming three intermolecular hydrogen bonds (inter-HBs) per molecule with the polymer chain. The CA molecule apparently diminishes the slow modes (with lower peak temperatures and peak heights) of the polyacrylate, although it has a higher glass transition temperature (T_g) than the acrylic matrix, and the rigid CA-bridged HB network significantly amplifies the α-relaxation near T_g (with higher peak temperatures and peak heights). Consequently, the mixtures exhibit a diminishing slow mode that gradually merges with the prominent α-peak with increasing CA loadings. The anomalous dynamics concerning the opposite behaviors of the slow mode and α-relaxation was further rationalized in terms of dissociation of inter-HBs when the temperature is higher than T_g, together with the small molecule-alleviated macromolecular connectivity. This work provides essential insights into the slow dynamics of such HB-driven hybrids, and paves the way for tailoring the viscous flow properties of the hybrid material from a molecular level perspective.

Puncture characterization of multilayered polypropylene homopolymer/ethylene 1-octene copolymer sheets

Both the puncture strength and energy of the multilayered sheets were significantly higher than those of the conventional blend.

Evaluation of the fracture behaviors of fluoropolymer binders with the essential work of fracture (EWF)

The beforehand evaluation of the fracture toughness and behaviors of the polymer binder through EWF can give a reliable feedback to the final fracture toughness of PBX.

Crystallization and molecular dynamics of ethylene-vinyl acetate copolymer/butyl rubber blends

In this article, butyl rubber (IIR) was blended with ethylene-vinyl acetate copolymer (EVA) through a molten method. In the blends, IIR is beneficial to the crystallization of EVA, while EVA confined the molecular motions of IIR.