3D Printing
News Videos Newsletter Contact us
Home / Medical / Tuneable Stiffness from Crosslinked Polymers
qidi

Tuneable Stiffness from Crosslinked Polymers

October 12, 2020

Tunable stiffness is highly desirable in the world of medical implant manufacture.

When 3D printing prosthetics (especially bone replacements) it’s important to get the variable stiffness of the bone correct. Bones are not solid. They have little structures / voids that vary in size and distribution throughout the bone, allowing the bone to flex non-uniformly depending on where the load is applied.

When you put fully dense structure (such as a solid titanium hip-joint) inside a body, it can cause stress shielding as it connects with the existing body structures, and this can result in patient injury, deterioration of the joints over time, and ultimately, a new replacement being needed to replace the old one.

We have seen geometric solutions for this in the form of orthopedic-centred topology optimization and generative design, which aims to replicate those little structures (named “trabeculae”) in an implant. The varying density of the structures along the bone allow flex at certain points of the bone.

medical-topology
Related Story
Topology Optimization for Compliant Medical Devices

We have not seen much however in the polymer science side, but that may all be about to change thanks to ongoing research from the Texas A&M University and the U.S. Army’s Combat Capabilities Development Command’s Army Research Laboratory, who have managed to print a polymer that can be tuned to a specific stiffness defending on the application.

Crosslinking

Synthetic polymers are usually made rubbery by addition of a hardener, which crosslinks the material’s long polymer chains.

“We hijacked the hardener, and attached some molecules that can bond and rebond at a certain temperature,” said Frank Gardea, a researcher at the Army Research Laboratory.

Now when the material is heated up, it will run like a fluid, rather than just melt into a blob like a traditional elastic polymer. Additionally, when the fluid cools, it will harden again, which is a useful property to have when 3D printing. .

“The temperature of the print bed is much cooler than the nozzle, so as it’s being printed, it solidifies because of this chemistry,” said Gardea.

Adding more crosslinks to the polymer chains increases the stiffness of the polymer.

The team also discovered (accidentally) that the new material has the ability to self-heal. When the surfaces of two pieces of the material were placed together, it was observed that the two halves started to rebond to each other. Within 12 hours the 2 parts had become one, with no joins. Typically the application of heat or some chemical would be needed to get the polymers to join together so efficiently. In this case, all they used was time.

“When a defect forms, it breaks that dynamic bond, and when broken, it becomes active. It wants to resolve itself; it looks for a partner to bond to,” said Gardea.

In addition to stiffening the polymer, the team claims that they can make programmable structures with the parts changing shape under application of heat.

For example, they have built a model of a hand using this material, which can change from a clenched fist into a peace sign.

“Ideally, the goal would be to have the material do an infinite amount of shapes. We are right now at two. We are limited because the chemistry only has two states,” said Gardea.

Self healing skins have a wide range of applications ranging from aircraft skin, to artificial limbs.

Share:
WhatsApp Twitter Facebook LinkedIn Buffer Reddit E-mail
About the author | Phillip Keane
Phillip is an aerospace engineer from UK. He is a graduate of Coventry University (UK), International Space University (France) and Nanyang Technological University (Singapore), where he studied Advanced Manufacturing at the Singapore Centre for 3D Printing.
Join our newsletter

Our newsletter is free & you can unsubscribe any time.

Latest posts

Cornell Researchers Develop 3D Printing Method for Enhanced Superconductors

Cornell University researchers have developed a one-step 3D printing method that produces superconductors with improved properties. The research, published August 19 in Nature... read more »

News
Cornell Researchers Develop 3D Printing Method for Enhanced Superconductors

Scottish Maritime Project Shows Promise for 3D Printed Ship Components

A Scottish project using large-scale additive manufacturing for shipbuilding components has completed its second phase, demonstrating potential benefits for the maritime industry. The... read more »

News
Scottish Maritime Project Shows Promise for 3D Printed Ship Components

Navy Maintenance Center Uses 3D Printing to Replace Destroyer Pump Component at Fraction of Conventional Cost

The Southeast Regional Maintenance Center (SERMC) has successfully used 3D printing to manufacture a replacement cooling rotor for an Arleigh Burke-class guided missile... read more »

Military
Navy Maintenance Center Uses 3D Printing to Replace Destroyer Pump Component at Fraction of Conventional Cost

Rapid Fusion Launches AI Assistant for Large-Format 3D Printers

British manufacturer Rapid Fusion has introduced "Bob," an AI-powered assistant designed to optimize operations for its large-format 3D printing systems. The company developed... read more »

News
Rapid Fusion Launches AI Assistant for Large-Format 3D Printers

Creality Submits IPO Prospectus for Hong Kong Stock Exchange Listing

Shenzhen-based 3D printer manufacturer Creality has submitted a prospectus to the Hong Kong Stock Exchange for a main board listing. The company began... read more »

News
Creality Submits IPO Prospectus for Hong Kong Stock Exchange Listing

Graphjet Technology Partners with Malaysian University on 3D-Printed Heat Sink Development

Graphjet Technology has entered into a collaboration agreement with the Centre for Materials Engineering and Smart Manufacturing (MERCU) at Universiti Kebangsaan Malaysia (UKM).... read more »

News
Graphjet Technology Partners with Malaysian University on 3D-Printed Heat Sink Development

Humtown drives US Manufacturing Comeback with Additive Sand Casting

Humtown Products, an Ohio-based company, is positioning itself to serve manufacturers looking to bring production back to the United States. The company specializes... read more »

News
Humtown drives US Manufacturing Comeback with Additive Sand Casting

Oak Ridge National Laboratory Releases Advanced Dataset for 3D Printing Quality Monitoring

Oak Ridge National Laboratory has released a comprehensive dataset for its Peregrine software, which monitors and analyzes parts created through powder bed additive... read more »

News
Oak Ridge National Laboratory Releases Advanced Dataset for 3D Printing Quality Monitoring

Creality Expands Flagship Lineup with K2 and K2 Pro 3D Printers

Creality has announced the launch of the K2 and K2 Pro, two new additions to its high-end K series. Built on a rigid... read more »

3D Printers
Creality Expands Flagship Lineup with K2 and K2 Pro 3D Printers

Farsoon and Stark Future Complete KLINGA Project, Producing Over 1,000 Titanium Parts

Farsoon Europe GmbH and Stark Future have completed the KLINGA Project, a collaborative engineering initiative that produced more than 1,000 titanium parts using... read more »

3D Printing Metal
Farsoon and Stark Future Complete KLINGA Project, Producing Over 1,000 Titanium Parts

Social

  • Facebook Facebook 3D Printing
  • Linkedin Linkedin 3D Printing
Join our newsletter

Our newsletter is free & you can unsubscribe any time.

Featured Industries

  • Automotive
  • Aerospace
  • Construction
  • Dental
  • Environmental
  • Electronics
  • Fashion
  • Medical
  • Military
  • QIDI Tech Q1 Pro

    • - Print size: 245 x 245 x 245 mm
    • - 600mm/s max speed
    More details »
    $449.00 QIDI Store
    Buy Now
  • QIDI Plus4

    • - Print size: 305 x 305 x 280 mm
    • - print temperature of 370°C
    More details »
    $799.00 QIDI Store
    Buy Now
  • Snapmaker Artisan Premium 3-in-1

    • - Print size: 400 x 400 x 400 mm
    • - comes with enclosure
    More details »
    $2,999.00 Snapmaker
    Buy Now
  • QIDI Tech X-Max 3

    • - Print size: 325 x 325 x 315 mm
    • - fully enclosed
    More details »
    $799.00 QIDI Store
    Buy Now

Company Information

  • What is 3D Printing?
  • Contact us
  • Join our mailing list
  • Advertise with us
  • Media Kit
  • Nederland 3D Printing

Blog

  • Latest News
  • Use Cases
  • Reviews
  • 3D Printers
  • 3D Printing Metal

Featured Reviews

  • Anycubic Photon Mono M5s
  • Creality Ender 5 S1
  • The Mole 3D Scanner
  • Flashforge Creator 3 Pro

Featured Industries

  • Automotive
  • Aerospace
  • Construction
  • Dental
  • Environmental
  • Electronics
  • Medical
  • Military
  • Fashion
  • Art
2025 — Strikwerda en Dehue
  • Home
  • Join our mailing list
  • Contact us
Blog
  • Latest News
  • Use Cases
  • Reviews
  • 3D Printers
  • 3D Printing Metal
Featured Industries
  • Automotive
  • Aerospace
  • Construction
  • Dental
  • Environmental
  • Electronics
  • Medical
  • Military
  • Fashion
  • Art
Company Information
  • What is 3D Printing?
  • Contact us
  • Join our mailing list
  • Advertise with us
  • Media Kit
  • Nederland 3D Printing