Wood Bonded by Magnetocuring Glue

NTU Prof Raju holding and bending two items of wooden bonded within the center by the magnetocuring glue, to exhibit its robust bonding energy. Credit score: NTU Singapore

A possible boon to inexperienced manufacturing, the brand new glue saves on power, time and house.

Scientists from Nanyang Technological College, Singapore (NTU Singapore), have developed a brand new method to remedy adhesives utilizing a magnetic subject.

Typical adhesives like epoxy that are used to bond plastic, ceramics, and wooden are usually designed to remedy utilizing moisture, warmth, or mild. They usually require particular curing temperatures, starting from room temperature as much as 80 levels Celsius.

The curing course of is critical to cross-link and bond the glue with the 2 secured surfaces because the glue crystallizes and hardens to realize its closing energy.

NTU’s new “magnetocuring” glue can remedy by passing it by a magnetic subject. That is very helpful in sure environmental situations the place present adhesives don’t work nicely. Additionally, when the adhesive is sandwiched between insulating materials like rubber or wooden, conventional activators like warmth, mild and air can’t simply attain the adhesive.

Merchandise corresponding to composite bike frames, helmets, and golf golf equipment, are at the moment made with two-part epoxy adhesives, the place a resin and a hardener are combined and the response begins instantly.

For producers of carbon fiber – skinny ribbons of carbon glued collectively layer by layer – and makers of sports activities gear involving carbon fiber, their factories use giant, high-temperature ovens to remedy the epoxy glue over many hours. This energy-intensive curing course of is the primary cause for the excessive price of carbon fiber.

The brand new “magnetocuring” adhesive is made by combining a typical commercially accessible epoxy adhesive with specifically tailor-made magnetic nanoparticles made by the NTU scientists. It doesn’t should be combined with any hardener or accelerator, in contrast to two-component adhesives (which has two liquids that should be combined earlier than use), making it straightforward to fabricate and apply.

It bonds the supplies when it’s activated by passing by a magnetic subject, which is well generated by a small electromagnetic machine. This makes use of much less power than a big standard oven.

Magnetocuring Glue on Cotton Mesh

Assoc Prof Steele (left) and Dr. Richa curing the magnetocuring glue on a cotton mesh utilizing an electromagnetic subject. Credit score: NTU Singapore

For instance, one gram of magnetocuring adhesive might be simply cured by a 200-Watt electromagnetic machine in 5 minutes (consuming 16.6 Watt Hours). That is 120 occasions much less power wanted than a conventional 2000-Watt oven which takes an hour (consuming 2000 Watt Hours) to remedy standard epoxy.

Developed by Professor Raju V. Ramanujan, Affiliate Professor Terry Steele and Dr. Richa Chaudhary from the NTU Faculty of Supplies Science and Engineering, the findings have been printed within the scientific journal Utilized Supplies Immediately and supply potential utility in a variety of fields.

This contains high-end sports activities gear, automotive merchandise, electronics, power, aerospace and medical manufacturing processes. Laboratory assessments have proven that the brand new adhesive has a energy as much as 7 megapascals, on par with most of the epoxy adhesives in the marketplace.

Assoc Prof Steele, an skilled in varied sorts of superior adhesives, defined: “Our key growth is a method to remedy adhesives inside minutes of publicity to a magnetic subject, whereas stopping overheating of the surfaces to which they’re utilized. That is essential as some surfaces that we wish to be a part of are extraordinarily heat-sensitive, corresponding to versatile electronics and biodegradable plastics.”

How “magnetocuring” glue works

The brand new adhesive is manufactured from two foremost elements – a commercially accessible epoxy that’s cured by warmth, and oxide nanoparticles comprised of a chemical mixture together with manganese, zinc and iron (MnxZn1-xFe2O4).

These nanoparticles are designed to warmth up when electromagnetic power is handed by them, activating the curing course of. The utmost temperature and charge of heating might be managed by these particular nanoparticles, eliminating overheating and hotspot formation.

NTU Assoc Prof Terry Steele, Prof Raju V. Ramanujan and Dr. Richa Chaudhary

(Left to proper) NTU Assoc Prof Terry Steele, Prof Raju V. Ramanujan and Dr Richa Chaudhary holding up varied smooth and arduous supplies bonded by their new magnetocuring glue. Credit score: NTU Singapore

With out the necessity for giant industrial ovens, the activation of the glue has a smaller footprint in house and power consumption phrases. The power effectivity within the curing course of is essential for inexperienced manufacturing, the place merchandise are made at decrease temperatures, and use much less power for heating and cooling.

As an example, producers of sports activities footwear usually have issue heating up the adhesives in between the rubber soles and the higher half of the shoe, as rubber is a warmth insulator and resists warmth transmission to the standard epoxy glue. An oven is required to warmth up the shoe over a very long time earlier than the warmth can attain the glue.

Utilizing magnetic-field activated glue bypasses this issue, by immediately activating the curing course of solely within the glue.

The alternating magnetic subject may also be embedded on the backside of conveyor belt methods, so merchandise with pre-applied glue might be cured after they cross by the magnetic subject.

Enhancing manufacturing effectivity

Prof Raju Ramanujan, who’s internationally acknowledged for his advances in magnetic supplies, collectively led the mission and predicts that the know-how may enhance the effectivity of producing the place adhesive joints are wanted.

“Our temperature-controlled magnetic nanoparticles are designed to be combined with current one-pot adhesive formulations, so most of the epoxy-based adhesives in the marketplace may very well be transformed into magnetic field-activated glue,” Prof Ramanujan mentioned.

“The velocity and temperature of curing might be adjusted, so producers of current merchandise may redesign or enhance their current manufacturing strategies. For instance, as a substitute of making use of glue and curing it half by half in a traditional meeting line, the brand new course of may very well be to pre-apply glue on all of the components after which remedy them as they transfer alongside the conveyor chain. With out ovens, it could result in a lot much less downtime and extra environment friendly manufacturing.”

First writer of the research, Dr. Richa Chaudhary mentioned, “The curing of our newly-developed magnetocuring adhesive takes solely a number of minutes as a substitute of hours, and but is ready to safe surfaces with excessive energy bonds, which is of appreciable curiosity within the sports activities, medical, automotive and aerospace industries. This environment friendly course of may also result in price financial savings because the house and power wanted for standard warmth curing are decreased considerably.”

This three-year mission was supported by the Company for Science, Know-how and Analysis (A*STAR).

Earlier work on heat-activated glue used an electrical present flowing by a coil, generally known as induction-curing, the place the glue is heated and cured from exterior. Nevertheless, its drawbacks embody overheating of the surfaces and uneven bonding because of hotspot formation throughout the adhesive.

Shifting ahead, the staff hopes to interact adhesive producers to collaborate on commercializing their know-how. They’ve filed a patent by NTUitive, the college’s innovation and enterprise firm. They’ve already obtained curiosity of their analysis from sporting items producers.

Reference: “Magnetocuring of temperature failsafe epoxy adhesives” by Richa Chaudhary, Varun Chaudhary, Raju V. Ramanujan and Terry W.J. Steele, 15 September 2020, Utilized Supplies Immediately.
DOI: 10.1016/j.apmt.2020.100824

By Rana

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