BESSY II: New procedure for better thermoplastics

in nano-IR imaging, the layer structures of the pure PVDF/PLLA mixture (left) and with the SAD additive (right) are clearly distinguishable. The light and dark colours correspond to the PLLA and PVDF phases, respectively. When SAD is added, the domain sizes of the two phases are reduced.
Credit: TU Eindhoven/HZB / License CC BY-SA

Thermoplastic blends, produced by a new process, have better resilience. Now, experiments at the IRIS beamline show, why: nanocrystalline layers increase their performance.

Bio-based thermoplastics are produced from renewable organic materials and can be recycled after use. Their resilience can be improved by blending bio-based thermoplastics with other thermoplastics. However, the interface between the materials in these blends sometimes requires enhancement to achieve optimal properties. A team from the Eindhoven University of Technology in the Netherlands has now investigated at BESSY II how a new process enables thermoplastic blends with a high interfacial strength to be made from two base materials: Images taken at the new nano station of the IRIS beamline showed that nanocrystalline layers form during the process, which increase material performance.

Bio-based thermoplastics are considered environmentally friendly, as they are sourced from non-petroleum-based raw materials and can be recycled just like standard thermoplastics. A thermoplastic base material is Polylactic acid (PLA), which can be produced from sugar cane or corn. Researchers around the world are working to optimise the properties of PLA-based plastics, for example by mixing them with other thermoplastic base materials. However, this is a real challenge.

A new process for better blends

Now, a team from the TU Eindhoven led by Prof. Ruth Cardinaels is showing how PLA can be successfully mixed with another thermoplastic. They developed a process in which certain PLA-based copolymers (e.g. SAD) are formed during production, which facilitate the mixing of the two raw materials by forming particularly stable (stereo)-crystalline layers at the interfaces between the different polymer phases (ICIC strategy).

Insights at the IRIS-Beamline

At BESSY II, they have now discovered which processes ensure that the mechanical properties of the mixed thermoplastic are significantly better. To do so, they examined pure 50% blends of the thermoplastics PLA and polyvinylidene fluoride (PVDF) as well as samples with the PLA-based copolymers at the IRIS beamline of BESSY II.

Stereocomplex crystals at the interfaces

Using infrared spectroscopy on the IRIS beamline, PhD student Hamid Ahmadi was able to demonstrate the formation of the PLA-based copolymer SAD. Further X-ray measurements showed how the formation of SAD affects the crystallisation behaviour. The new nano imaging and spectroscopy capabilities at the IRIS beamline allow for advanced chemical visualization and identification from sample areas as small as 30 nm. This precision was crucial in determining that the stereocomplex crystals are exclusively located at the interface. Infrared nanoscopy images showed a 200–300 nm thick layer of stereocomplex crystals at the interfaces.

Reason for more stability

The formation of stereocomplex crystals at the interfaces increases the stability and crystallisation temperature. Nucleation at the interface accelerates the overall crystallisation process within the PLLA/PVDF blend. In addition, the interfacial crystalline layer improves the transfer of mechanical stresses between the phases and thus the tensile properties; the elongation at break even increases by up to 250 %.

“By elucidating the location and distribution of the crystalline layer in our samples, we could understand the procedure of mixing much better”, Hamid Ahmadi says. “By developing a new strategy we have cleared a path for the development of high-performance polymer blends”, Ruth Cardinaels adds.

Journal: ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.4c10829
Method of Research: Experimental study
Subject of Research: Not applicable
Article Title: Toughening immiscible polymer blends: the role of interface-crystallization-induced compatibilization explored through nanoscale visualization
Article Publication Date: 16-Oct-2024
COI Statement: none

Media Contact

Antonia Roetger
Helmholtz-Zentrum Berlin für Materialien und Energie
antonia.roetger@helmholtz-berlin.de
Office: 0049-308-062-43733

Expert Contact

Prof. Dr. Ir. Ruth Cardinaels
TU Eindhoven
R.M.Cardinaels@tue.nl

Media Contact

Antonia Roetger
Helmholtz-Zentrum Berlin für Materialien und Energie

All latest news from the category: Materials Sciences

Materials management deals with the research, development, manufacturing and processing of raw and industrial materials. Key aspects here are biological and medical issues, which play an increasingly important role in this field.

innovations-report offers in-depth articles related to the development and application of materials and the structure and properties of new materials.

Back to home

Comments (0)

Write a comment

Newest articles

NASA: Mystery of life’s handedness deepens

The mystery of why life uses molecules with specific orientations has deepened with a NASA-funded discovery that RNA — a key molecule thought to have potentially held the instructions for…

What are the effects of historic lithium mining on water quality?

Study reveals low levels of common contaminants but high levels of other elements in waters associated with an abandoned lithium mine. Lithium ore and mining waste from a historic lithium…

Quantum-inspired design boosts efficiency of heat-to-electricity conversion

Rice engineers take unconventional route to improving thermophotovoltaic systems. Researchers at Rice University have found a new way to improve a key element of thermophotovoltaic (TPV) systems, which convert heat…