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1. Quantifying the contributions of energy storage in a thermoset shape memory polymer with high stress recovery: A molecular dynamics study

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   Wick, Collin D. ; Peters, Andrew J. ; Li, Guoqiang ( January 2021 , Polymer)

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2. Coir/glass hybrid fiber reinforced thermoset polymer composite laminates with room-temperature self-healing and shape memory functions

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3. Thermoset polymer composites with gradient natural and synthetic fiber reinforcement: Self-healing, shape-memory, and fiber recyclability

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4. Thermoset composite recycling – Driving forces, development, and evolution of new opportunities

   https://doi.org/10.1177/0021998317720000  

   Overcash, Michael ; Twomey, Janet ; Asmatulu, Eylem ; Vozzola, Eric ; Griffing, Evan ( April 2018 , Journal of Composite Materials)

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   Thermoset composites represent a substantial challenge for recycling, even as composite products increase in market interest. The concept of putting all future thermoset composite products into landfills over the next decades is unlikely to continue. This paper examines the three eras in the history of thermoset product recycling, the drivers for increased recycling, and possible future trends. Technology for managing thermoset composite products at end-of-life first focused on retrieving fiber and to a lesser extent resin. Then in a second era, research focused on better utilization of recovered fiber and finally the third era is now keeping more of the original resin–fiber structure to reuse these composites. Drivers are emerging to stimulate thermoset recycling, including States with success in recycling other challenging products (tires, carpets, automobile parts, etc.) setting policy and fees to encourage recycling. The evolution of heat recovery as a thermoset recycling option in Europe is another driver. Additionally, efforts at certification of recycled fiber quality may stimulate greater reuse. 

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5. Effect of crosslinking fraction, hardener functionality and topological quality on stress recovery of thermoset shape memory polymers: a coarse-grained molecular dynamics study

   https://doi.org/10.1088/1361-665X/acfa7d  

   Nourian, Pouria ; Wick, Collin D ; Peters, Andrew J ( September 2023 , Smart Materials and Structures)

   We analyzed the effects of crosslinking fraction and number of functional sites per hardener molecule on the stress recovery and topology of thermoset shape memory polymers (TSMPs) via coarse-grained molecular dynamics simulations. After systematically varying the quality of the crosslinked network by manipulating the number of unique epoxies reacted with each hardener, we found that two fingerprints correlate well with stress recovery of TSMPs. These fingerprints are the fraction of epoxy molecules connected to two distinct hardener molecules, and the fraction of molecules that are part of the largest or main network in the system. Their product can be used as a topological score ($S_{\text{topo}}$) to quantify the topological feature of the network. When analyzing stress recovery as a function of$S_{\text{topo}}$, we found a strong correlation between$S_{\text{topo}}$and recovery stress. Moreover, we observed that while a higher crosslinking fraction did frequently lead to a higher stress recovery, many exceptions existed. High functionality hardeners tend to exhibit higher stress recovery at similar$S_{\text{topo}}$, especially at high (>0.65)$S_{\text{topo}}$. These results suggest that increasing the number of functional sites per hardener molecule combined with improving the topology of the network with a method such as semi batch monomer addition can lead to an improvement in the stress recovery of TSMPs.

    

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