Experimental investigation on self-activated healing performance of thermosetting polyurethane prepared by tungsten (VI) chloride catalyst

Abstract

Polymers and polymeric composites are widely used for various applications due to their outstanding and wide range of properties. Polyurethanes, existing in different types, are novel and versatile polymers with excellent mechanical properties. Thermosetting polyurethane resins are among the most widely used polyurethanes wherein their manufacturing and developing have been introduced during the last few years. Self-healing materials have been inspired by biological systems in which damages provoke healing responses. It is almost cost-effective to use self-healing materials in commercial applications. This study investigates a novel self-activated approach in thermosetting polyurethane resins. A tungsten (VI) chloride (WCl 6 ) catalyst, a co-activator (phenylacetylene) and a dissolution agent (nonylphenol) were used for the onset of ring-opening metathesis polymerization of dicyclopentadiene. Here different percentages of a catalyst in polyurethane resins were used, the impacts of which on fracture toughness and healing efficiency were also studied. To examine healing efficiency, samples with tapered double-cantilever beam geometry were prepared and using the selfactivated method, the development of thermosetting polyurethane self-healing was investigated. The results showed that the concentration of catalyst affects the basic properties of the material and healing efficiency of the composite. The highest healing efficiency of 97% was obtained for a 3 wt% catalyst.

In situ encapsulation technique for fabrication of self‐healing thermosetting polyurethane with tungsten (VI) chloride

“…The healing efficiency obtained in such a situation was 64%. As reported in, 29 we obtained a healing efficiency of 97% for 3 wt% WCl 6 catalyst using self‐activated technique, indicating the fact that the in situ procedure leads to less healing efficiency than the self‐activated technique. The reason is that in the self‐activated method, the healing agent is injected manually using a Hamilton syringe inside the crack created in the test sample, while in the in situ method, the healing agent enclosed inside the microcapsules penetrates into the crack due to the capillary action when the crack propagates and randomly collides with the microcapsules in its path and breaks them.…”

“…Moreover, its EDS analysis shows the existence of DCDP on the surface of the sample, and it is almost fully synthesized and polymerized with the catalyst. A comparison of EDS analysis, the image in Figure 12A, with EDX analysis presented in reference [19, 29], adequately validates the polymerization of the healing agent with the catalyst. From the EDS analysis at zone B in Figure 11 and Table 4, it is evident that the percentage of tungsten element is 61% which signifies the existence of tungsten (VI) chloride catalyst next to microcapsules trapped in polyurethane resin matrix.…”

“…In our previous study, 29 we examined self‐healing capability of thermosetting polyurethane resin using self‐activated and manual techniques, with the maximum healing efficiency obtained with the 3 wt% tungsten (VI) chloride catalyst. As a consequence, the present work deals with investigating self‐healing capability of thermosetting polyurethane resins using in situ technique; the urea–formaldehyde microcapsules containing dicylopentadiene as the healing agent, phenylacetylene as the coactivator, and nonylphenol as the dissolution agent were synthesized and distributed together with tungsten (VI) chloride catalyst into polyurethane thermosetting resin in 5 and 3 wt%, respectively.…”