A potential boon to green construction, new glue saves energy, time and space.
Scientists at Nanyang Technological University, Singapore (NTU Singapore) have developed a new way of curing adhesives using a magnetic field.
Conventional adhesives such as epoxy that are used to bind plastics, ceramics, and wood are usually designed to cure using moisture, heat, or light. They often require specific curing temperatures, ranging from room temperature to 80 degrees Celcius.
The curing process is necessary to cross-link and bond the glue with two secure surfaces as the glue crystallizes and hardens to achieve its ultimate strength.
NTU’s new “magnetocuring” glue can be cured by passing through a magnetic field. This is very useful in some environmental situations where current adhesives do not work well. Furthermore, when the adhesive is sandwiched between insulating materials such as rubber or wood, traditional activators such as heat, light, and air do not easily reach the adhesive.
Products such as composite bike frames, helmets and golf clubs are currently two-part epoxy adhesives, where a resin and a hardener are mixed and the reaction begins immediately.
For manufacturers of carbon fiber – thin ribbons of carbon glued together layer-by-layer – and manufacturers of sports equipment containing carbon fiber, their factory large, high-temperature ovens to fix epoxy glue in several hours Let’s use. This energy-intensive curing process is the main reason for the high cost of carbon fiber.
The new “magnetocuring” adhesive is a unique commercially available epoxy adhesive with uniquely available magnetic nanoparticles made by NTU scientists. Unlike two-component adhesives (which contain two liquids that must be mixed before use), there is no need to be mixed with any hardener or accelerator, making it easy to manufacture and apply. .
It bonds materials when activated through passing a magnetic field, which is easily generated by a small electromagnetic device. It uses less energy than a large conventional oven.
For example, one gram of magnetocorbing adhesive can be easily cured by a 200 watt electromagnetic device in five minutes (consuming 16.6 watt hours). It requires 120 times less energy than a traditional 2000-watt oven that consumes one hour (consumes 2000 watt hours) to cure a traditional epoxy.
Professor Raju V. Ramanujan, Associate Professor Terry Steele and Drs. The findings of NTU School of Materials Science and Engineering, developed by Richa Chaudhary, were published in the journal Scientific. Content applied today And provide potential applications over a wide area.
This includes high-end sports equipment, automotive products, electronics, energy, aerospace and medical manufacturing processes. Laboratory tests have shown that the new adhesive has a strength of up to 7 megapixels, which is comparable to many epoxy adhesives on the market.
Assoch Pro Steel, an expert on a variety of advanced adhesives, explained: “Our main development is a way to fix the adhesive within minutes of exposure to a magnetic field, while preventing overheating of surfaces on which They are implemented. This is important because some of the surfaces we want to attach are extremely sensitive, such as flexible electronics and biodegradable plastics. “
How “magnetocuring” glue works
The new adhesive is composed of two main components – a commercially available epoxy that is cured through heat, and oxide nanoparticles made from a chemical combination including manganese, zinc, and iron (MnxZn1-xFe2O4).
These nanoparticles are designed to heat up when electromagnetic energy is passed through them, activating the curing process. The maximum temperature and rate of heating can be controlled by these special nanoparticles, eliminating overheating and the formation of hotspots.
Without the need for a large industrial oven, the activation of the glue has a small footprint in terms of space and energy consumption. Energy efficiency in the curing process is critical for green manufacturing, where products are made at low temperatures, and use less energy for heating and cooling.
For example, manufacturers of sports shoes often have difficulty heating the adhesive between the rubber soles and the upper half of the shoe, as the rubber is a heat insulator and supports heat transmission in conventional epoxy glue. An oven is required to heat the shoe for a long time before the heat reaches the glue.
Using magnetic-field activated glue only by activating the curing process in the glue itself bypasses this difficulty.
Optional magnetic fields can also be embedded at the bottom of the conveyor belt system, so pre-applied glue products can be fixed when they pass through the magnetic field.
Improve manufacturing efficiency
Prof Raju Ramanujan, internationally recognized for his advances in magnetic materials, jointly led the project and predicted that the technology could increase the efficiency of manufacturing where adhesive joints are required.
“Our temperature-controlled magnetic nanoparticles are designed to blend with existing one-pot adhesive aggregates, so many epoxy-based adhesives on the market can be converted into magnetic field-activated glue,” Professor Ramanujan said.
“Curing speed and temperature can be adjusted, so manufacturers of existing products can redesign or improve their existing manufacturing methods. For example, instead of applying the glue and fixing it by parting in a conventional assembly line, the new process may be to pre-apply the glue to all parts and then to fix them, as they would with the conveyor chain Let’s go. Without an oven, this would lead to much less downtime and more efficient production. “
The first author of the study, Drs. Richa Chaudhary said, “Our newly developed magnetocurring adhesive takes only several minutes instead of hours, and is still capable of securing surfaces with high strength bonds, which are of great interest in sports, medicine, automotive. And the aerospace industry. This efficient process can also bring about cost savings as the space and energy required for conventional heat treatment is significantly reduced. “
This three-year project was supported by the Agency for Science, Technology and Research (A * STAR).
Previous work on heat-activated glue used an electric current that flowed through a coil, known as induction-curing, where the glue heats up and cures from the outside. However, its shortcomings include uneven bonding due to overheating of surfaces and the formation of hotspots within the adhesive.
Going forward, the team hopes to collaborate on the commercialization of its technology to adhesive manufacturers. He has filed a patent through the university’s innovation and venture company NTUitive. He has become interested in his research from sporting goods manufacturers.
References: Richa Chaudhary, Varun Chaudhary, Raju V. 15 September 2020, “Epoxy adhesives due to temperature failure” by Ramanujan and Terry WJ Steel. Content applied today.
DOI: 10.1016 / j.apmt.2020.100824