Non-poisonous, flame-retardant composite product based upon bio-epoxy made from plant-source tannic acid. 99% environmentally friendly recycling within 10s of minutes simply by liquifying in water.
A flame-retardant carbon-fiber-reinforced composite product has actually been established. Korea Institute of Science and Technology (KIST) revealed that a research study group from its Institute of Advanced Composite Materials, headed by Dr. Yong chae Jung utilized plant-originated tannic acid* to establish a flame-retardant carbon fiber-reinforced plastic** (CFRP), and likewise provided a technique for its environmentally friendly recycling.
*Tannic acid: A compound that is plentiful in nature, tannic acid is a kind of polyphenol that is typically manufactured by plants.
**Carbon fiber-reinforced plastic: An advanced light-weight composite product enhanced by carbon fiber, with high rigidness and high flexibility that appropriates for a wide variety of applications.
CFRP, a composite product which contains carbon fiber, which has to do with 4 times lighter than steel yet 10 times more powerful, is extensively utilized in the aerospace, automobile, shipbuilding, and sports devices markets. Structurally, CFRP is comprised of carbon fiber and epoxy resin, which serve functions in this composite product comparable to the particular functions that strengthening rods and cement play in concrete structures. To attain mechanical rigidness, the binding of carbon fiber and epoxy resin in CFRP should be strong. Moreover, CFRP should be fire-safe as it is utilized for functions carefully associated to daily life, e.g. usage as a building and construction product. To cause these qualities in CFRP, in some cases it is manufactured with ingredients.
Due to its vulnerability to heat, CFRP had actually been made fire-safe by including a halogen flame-retardant***. However, using halogen in CFRP was prohibited worldwide, since it produces poisonous compounds when incinerated for recycling. As such, the job at hand was to make CFRP flame-retardant with using a non-toxic, safe product.
***Halogen: Elements that come from Group 17 on the table of elements, consisting of fluorine, chlorine, bromine, and iodine.
Jung Yong-chae, head scientist at KIST’s Institute of Advanced Composite Materials, looked for to enhance the mechanical rigidness and flame-retardance of CFRP with tannic acid, an environment-friendly compound. Tannic acid typically bonds highly with carbon fiber. It likewise develops into charcoal when burned. Charred tannic acid functions as a barrier that obstructs the inflow of external oxygen. By production epoxy resin from tannic acid and blending it into carbon fiber, the KIST research study group effectively established a CFRP that is strong and flame-retardant.
Unlike traditional epoxy resin that is susceptible to heat, epoxy resin made from tannic acid is flame-retardant and requires no ingredients. This suggests that the poisonous compounds produced when incinerating CFRP for recycling would no longer be an issue. Also, since traditional CFRP when burned reduced the efficiency of its epoxy resin, preventing total recycling, the research study group developed a brand-new recycling technique.
By liquifying CFRP in water in a supercritical fluid**** state – i.e. temperature level and pressure over a set level – over 99% of the CFRP might be recuperated without lowered carbon fiber efficiency. It was likewise discovered that epoxy resin when liquified produced a compound called carbon dots”*****,” which can be utilized as an electronic product (Optronics, Sensing, Bioimaging etc.,). Unlike the technique of recycling by incineration, which burns up epoxy resin leaving just the insufficient carbon fiber to be recycled, this brand-new technique of recycling makes it possible for the recycling of all parts of a composite product.
****Supercritical fluid: A compound with a temperature level and pressure above the crucial level. Related to expandability of gas and dissolvability of liquid. Water and co2 are compounds typically utilized as supercritical fluids. Supercritical water can liquify even gold.
*****Carbon dots: Carbon quantum dots, with carbon as their significant component, have the qualities of photoluminescence and a semiconductor, making them comparable to inorganic quantum dots. Due to stated qualities, carbon quantum dots are being extensively utilized in locations such as bio-imaging, sensing units, light-emitting diode (LED) lighting, natural solar batteries, and photocatalysts.
Head scientist Dr. Jung stated, “We have created a composite material with an expanded range of application that is a dramatic improvement over conventional carbon fiber-reinforced plastic in terms of flame-retardancy, mechanical rigidity, and recyclability. These improved traits are significant in that they determine the range of application of said composite material.” He included, “We will be reviewing the structure of this composite material to achieve even further improved properties and to further expand the range of its application.”
Reference: “Recyclable, flame-retardant and smoke-suppressing tannic acid-based carbon-fiber-reinforced plastic” by Young-O Kim, Jaehyun Cho, Young Nam Kim, Kun Won Kim, Byoung Wan Lee, Jae Woo Kim, Minkook Kim and Yong Chae Jung, 22 May 2020, Composites Part B: Engineering.
The research study, backed by the Ministry of Science and ICT, was carried out as an Institutional Research Program of the Korea Institute of Science and Technology. A journal short article describing the outcomes of the research study was released in the most recent problem of Composite Part B: Engineering, the leading worldwide journal in the field of products science and composite products (leading 2% of JCR).