COMPOSITES I
n a groundbreaking development for materials science, innovators at the Department of Energy’s Oak Ridge National Laboratory
(ORNL) have devised a closed-loop process for producing a resilient carbon-fi bre-reinforced polymer (CFRP) while eff iciently reclaiming all constituent materials. CFRP, renowned for its lightweight,
robust, and durable properties, holds immense potential for enhancing the performance and sustainability of various industries, including automotive, aerospace, and spacecraft manufacturing. However, traditional CFRPs pose signifi cant recycling challenges, often ending up as single-use materials with substantial environmental footprints. ORNL’s closed-loop technology, detailed in a publication in Cell Reports Physical Science, represents a pivotal advancement in addressing this pressing sustainability issue. Led by ORNL chemists Md
Anisur Rahman and Tomonori Saito, alongside postdoctoral fellow Menisha Karunarathna Koralalage, the research team has developed a novel approach to CFRP synthesis that revolutionises conventional manufacturing paradigms. Unlike traditional thermoset
materials, which undergo irreversible crosslinking upon synthesis, ORNL’s innovative system introduces dynamic chemical groups into the polymer matrix and carbon fi bres, enabling multiple reprocessing cycles without compromising mechanical properties such as strength and toughness. The cornerstone of ORNL’s
approach lies in the strategic incorporation of dynamic crosslinking, a process that imbues the CFRP with the ability to break and reform chemical bonds, facilitating seamless reprocessing and recycling. This dynamic bonding mechanism, combined with a robust interfacial adhesion between the polymer matrix and carbon fi bres, yields a highly resilient composite material capable of withstanding diverse environmental stresses and mechanical loads.
A CIRCULAR ECONOMY Central to the success of ORNL’s
A polymer, functionalised carbon fi bres and a crosslinker are mixed and cured – these
components can be retrieved by addition of a chemical compound named pinacol
RECLAIMING RESOURCES
A new process allows full recovery of starting materials from tough polymer composites
closed-loop system is its compatibility with circular economy principles, ensuring minimal material wastage and maximum resource eff iciency. Through meticulous experimentation and optimisation, the research team has achieved a closed-loop recycling process wherein 100% of the starting materials – including the crosslinker, polymer, and fi bres – are recovered and reincorporated into subsequent manufacturing cycles. Beyond its sustainability
credentials, the reversible crosslinked CFRP off ers a host of additional benefi ts, including rapid thermosetting, self-adhesive properties, and the ability to repair microcracks within the composite matrix. Drawing inspiration from nature’s dynamic interfaces, such as nacre found in mollusk shells,
the researchers have engineered a material that combines exceptional strength, resilience, and recyclability. Looking ahead, the research team
aims to explore the application of dynamic crosslinking in other composite materials, particularly glass-fi bre composites, with the goal of expanding the technology’s reach across diverse industries. By lowering costs and optimising
performance, ORNL’s closed-loop CFRP technology holds the promise of revolutionising various sectors, from renewable energy and transportation to construction and consumer goods, ushering in a new era of sustainable manufacturing and resource utilisation. ●
For more information visit
www.ornl.gov
www.engineerlive.com 39
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