Preparation and characterization of long chain branched polycarbonates with significantly enhanced environmental stress cracking behavior through gamma radiation with addition of difunctional monomer

Abstract

A series of long chain branched polycarbonates (LCB-PCs) was prepared with unique topological structures and significantly enhanced ESC properties.

Long‐Chain Hyperbranched Polymers: Synthesis, Properties, and Applications

“…The melt rheology study of LCHBPs shows some similarities with the classical HBPs with short subchains, such as enhanced zero shear viscosities with increased molecular weight, shear‐thinning behavior, and deviation from the linear reference in the van Gurp–Plamen plots . It should be noted that the entangled feature that usually did not occur in conventional HBPs might even be introduced to LCHBPs, but the length of the subchain should be substantially above the entanglement molecular weight .…”

“…The rheological measurements showed that the long‐chain hyperbranched structures of polycarbonate LCHBPs contributed to enhancements of storage modulus and complex viscosity ( Figure ) . More importantly, these LCHBPs exhibited significantly enhanced environmental stress cracking (ESC) property than corresponding linear polycarbonates, which was attributed to the increased free volume due to the introduction of HBP structures (Figure ) …”

“…The rheological properties and environmental stress cracking (ESC) behaviors of linear polycarbonates (PC) and polycarbonates based LCHBPs (LCB‐PC). Adapted with permission . Copyright 2016, The Royal Society of Chemistry.…”

“…Although excellent achievements have been made on HBPs, in contrast with linear polymers, the quite low viscosity and amorphous nature or high brittleness of HBP materials arising from their dendritic topologies with subchain lengths much shorter than the critical molecular weight for entanglement, give rise to poor processability and inferior mechanical properties, that are not possible for structural applications . Nevertheless, long‐chain hyperbranched polymers (LCHBPs), essentially the long‐chain analogs of HBPs with a linear long subchain segment between branching points, may combine the advantageous properties of HBPs and linear polymers, which may allow the formation of entanglements and also crystallinity like their linear segments, making them less brittle materials than their short‐chain analogs . When compared with linear polymers, LCHBPs possess lower solution and melt viscosity, better solubility, and a large number of terminal functional groups because of their hyperbranched architectures.…”

“…Besides their unique synthetic strategies and novel structural features or topologies, LCHBPs have displayed some novel properties in both bulk and solution states. The chain entanglements have turned out to probably occur in LCHBPs via rheological measurements, which make them feasible in structural applications . They also display some unique assembly morphologies or crystallinity behaviors due to their long‐chain topological architectures .…”