Nav: Home

3D printed tires and shoes that self-repair

February 05, 2019

Instead of throwing away your broken boots or cracked toys, why not let them fix themselves? Researchers at the University of Southern California Viterbi School of Engineering have developed 3D-printed rubber materials that can do just that.

Assistant Professor Qiming Wang works in the world of 3D printed materials, creating new functions for a variety of purposes, from flexible electronics to sound control. Now, working with Viterbi students Kunhao Yu, An Xin, and Haixu Du, and University of Connecticut Assistant Professor Ying Li, they have made a new material that can be manufactured quickly and is able to repair itself if it becomes fractured or punctured. This material could be game-changing for industries like shoes, tires, soft robotics, and even electronics, decreasing manufacturing time while increasing product durability and longevity.

The material is manufactured using a 3D printing method that uses photopolymerization. This process uses light to solidify a liquid resin in a desired shape or geometry. To make it self-healable, they had to dive a little deeper into the chemistry behind the material.

Photopolymerization is achieved through a reaction with a certain chemical group called thiols. By adding an oxidizer to the equation, thiols transform into another group called disulfides. It is the disulfide group that is able to reform when broken, leading to the self-healing ability. Finding the right ratio between these two groups was the key to unlocking the materials' unique properties.

"When we gradually increase the oxidant, the self-healing behavior becomes stronger, but the photopolymerization behavior becomes weaker," explained Wang. "There is competition between these two behaviors. And eventually we found the ratio that can enable both high self-healing and relatively rapid photopolymerization."

In just 5 seconds, they can print a 17.5-millimeter square, completing whole objects in around 20 minutes that can repair themselves in just a few hours. In their study, published in NPG Asia Materials, they demonstrate their material's ability on a range of products, including a shoe pad, a soft robot, a multiphase composite, and an electronic sensor.

After being cut in half, in just two hours at 60 degrees Celsius (four for the electronics due to the carbon used to transmit electricity) they healed completely, retaining their strength and function. The repair time can be decreased just by raising the temperature.

"We actually show that under different temperatures - from 40 degrees Celsius to 60 degrees Celsius - the material can heal to almost 100 percent," said Yu, who was first-author of the study and is studying structural engineering. "By changing the temperature, we can manipulate the healing speed, even under room temperature the material can still self-heal"

After conquering 3D-printable soft materials, they are now working to develop different self-healable materials along a range of stiffnesses, from the current soft rubber, to rigid hard-plastics. These could be used for vehicle parts, composite materials, and even body armor.
-end-
This study was published on February 1 and funded by the Air Force Office of Scientific Research Young Investigator Program (FA9550-18-1-0192) and National Science Foundation (CMMI-1762567).

University of Southern California

Related Engineering Articles:

Engineering a new cancer detection tool
E. coli may have potentially harmful effects but scientists in Australia have discovered this bacterium produces a toxin which binds to an unusual sugar that is part of carbohydrate structures present on cells not usually produced by healthy cells.
Engineering heart valves for the many
The Wyss Institute for Biologically Inspired Engineering and the University of Zurich announced today a cross-institutional team effort to generate a functional heart valve replacement with the capacity for repair, regeneration, and growth.
Geosciences-inspired engineering
The Mackenzie Dike Swarm and the roughly 120 other known giant dike swarms located across the planet may also provide useful information about efficient extraction of oil and natural gas in today's modern world.
Engineering success
Academically strong, low-income would-be engineers get the boost they need to complete their undergraduate degrees.
HKU Engineering Professor Ron Hui named a Fellow by the UK Royal Academy of Engineering
Professor Ron Hui, Chair Professor of Power Electronics and Philip Wong Wilson Wong Professor of Electrical Engineering at the University of Hong Kong, has been named a Fellow by the Royal Academy of Engineering, UK, one of the most prestigious national academies.
Engineering a better biofuel
The often-maligned E. coli bacteria has powerhouse potential: in the lab, it has the ability to crank out fuels, pharmaceuticals and other useful products at a rapid rate.
Pascali honored for contributions to engineering education
Raresh Pascali, instructional associate professor in the Mechanical Engineering Technology Program at the University of Houston, has been named the 2016 recipient of the Ross Kastor Educator Award.
Scaling up tissue engineering
A team at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A.
Engineering material magic
University of Utah engineers have discovered a new kind of 2-D semiconducting material for electronics that opens the door for much speedier computers and smartphones that also consume a lot less power.
Engineering academic elected a Fellow of the IEEE
A University of Bristol academic has been elected a Fellow of the world's largest and most prestigious professional association for the advancement of technology.

Related Engineering Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#532 A Class Conversation
This week we take a look at the sociology of class. What factors create and impact class? How do we try and study it? How does class play out differently in different countries like the US and the UK? How does it impact the political system? We talk with Daniel Laurison, Assistant Professor of Sociology at Swarthmore College and coauthor of the book "The Class Ceiling: Why it Pays to be Privileged", about class and its impacts on people and our systems.