Evaluation of disulfide chain extender effect on the mechanical properties of unsaturated polyurethane‐urea networks

Abstract

4-Aminophenyl disulfide and bis(4-aminophenyl)methane chain extenders containing hydroxyl-terminated polybutadienebased polyurethane-ureas are prepared one-shot to explore the effect of the chain extender structure on the elastomers mechanical properties. However, the results revealed that the participation of the disulfide chain extender in side reactions like thiol-ene and proton abstraction prevented disulfide metathesis reaction due to decomposing chain extender in the polyurethane-urea matrix. Also, these side reactions improved the phase mixing via chemical crosslinking between polyurethane-ureas soft and hard segments, too. Tensile test results showed higher stress strength of the elastomers in the presence of the disulfide chain extender in comparison with the nondisulfide bond containing elastomers. This result was in agreement with the observed result in dynamical mechanical analysis. Dynamic mechanical analysis results established that the absence of the disulfide bond in the polyurethane-urea matrix led to the higher viscous modulus. The swelling test revealed chemical crosslinking increased in the presence of the disulfide bond. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46309.

Synthesis of mechanically strong waterborne poly(urethane-urea)s capable of self-healing at elevated temperatures

“…20,30 The dynamic behaviour of the aromatic disulfide at reduced temperatures has subsequently been explored by several groups in the area of self-healing. [31][32][33] For example, using the same disulfide Yang et al synthesized a PU elastomer with improved tensile strength for which self-healing could be induced by heating to 60 °C. They observed that for more cross-linked materials a higher tensile strength was obtained, but this occurred with a concomitant lowering of the ability to self-heal.…”

Thermal induced intrinsic self‐healing in epoxy based elastomer coatings provided by disulfide metathesis reactions

“…However, the radical cleavage of the S-S bonds during raising temperature decreased the mechanical strength of the EP-DTPA samples. 41 Moreover, the performed metathesis reaction in these samples could be followed up in tan δ curve, too. The loss modulus enhancement by introducing of the DTPA in EP-DTPA samples was initiated from about 5 C. As a consequence, it was expected that the healing process for the prepared coatings initiated from upper temperature than room temperatures.…”

“…38 Considerably, the fabricated elastomer via their suggested method could be reshaped and reprocessed by room-temperature compression through rearrangements of the cross-linked. 38 In continuous to our previous studies on self-healing materials [39][40][41][42][43] and polymer properties, 25,44 self-heal epoxy coatings have been prepared using disulfide metathesis reaction. In this regard, an epoxy terminated chain extender with capability of performing reversible reaction has been synthesized via functionalization of 3,3 0 -dithiodipropionic acid (DTPA) with bisphenol A diglycidyl ether (DGEBA).…”

Synthesis of Polyetheramine Based Bonding Agents and Their Effect on Mechanical Properties of an AP/CL‐20/GAP Formulation

“…The chain extender is an available additive to solve this problem, but it cannot inhibit the dewetting, which may influence its effect on the contrary [21]. Abd Elall [1] used fatty monocarboxylic acid and dicarboxylic acid with methyl aziridinyl phosphine oxide (MAPO) to form (MSA) bonding agent which improved the mechanical properties especially strain value corresponding to stress value.…”