On the origin of brittle fracture of entangled polymer solutions and melts

Abstract

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Exploring the mechanism of fracture for entangled polymer liquids in extensional flow

“…4(c), the level of the critical stress is over 500 times higher than the plateau modulus, meaning that the polymer chains are highly stretched. In the elastic limit, the critical true stress at the fracture can be calculated as σc = 5G 0 N λ 2 c , 21 where λc is the critical stretch ratio of the polymer chains at the fracture. In Fig.…”

“…While there is no clear answer at this stage, it has been suggested by some research groups that scission of primary bonds plays the role. 20,21 Very recently, Wagner et al proposed that liquid fracture should be understood in terms of entropy. 21 However, this idea has been questioned by Wang.…”

“…20,21 Very recently, Wagner et al proposed that liquid fracture should be understood in terms of entropy. 21 However, this idea has been questioned by Wang. 22 Although fracture stops the flow of polymer liquids and should be understood as a noncontinuum process, the conditions that lead to fracture, e.g., stretch rate, critical strain, and critical stress, are still connected to polymer rheology and dynamics.…”

Highly Anisotropic Glassy Polystyrenes Are Flexible

“…Going back to the origin of flexibility as discussed above, compared with PS-285k-A, PS-285k-B has more molecular chain stretch in melt state [19][20], correspond-ing to a more pre-stretched network, and possibly more reduction of segmental friction. However, unlike mechanical rejuvenation which lowers the yield stress, PS-285k-B has an even higher yield stress.…”

Response to “Letter to the Editor: ‘Melt rupture unleashed by few chain scission events in fully stretched strands’” [J. Rheol. 63, 105 (2018)]

“…In his Letter to the Editor, Wang [1] advanced several arguments against the entropic fracture hypothesis of Wagner et al [2], which we discuss in the following.…”