Making polymers more productive

Liquid crystalline polymers are attractive high-performance engineering materials, used in fields as diverse as the manufacture of aircraft components, surgical instruments, barrier applications, and protective apparel.

They are endowed with high strength and stiffness, high chemical resistance, good dimensional stability, and a low linear thermal expansion coefficient. Their rigid rod nature gives them a low viscosity and low shrinkage. These properties render them useful for applications that require a combination of high strength and chemical inertness, including in small or thin mouldings.

Fig. 1: Applications of Liquid crystalline polymers
(Courtesy: Journal of Statistical Physics, Vol. 62, 985-995, 1991)

Liquid crystalline polymers (LCPs) are mainly used as a minor blending component in the synthesis of polymer composites with superior mechanical performance in association with thermoplastics. There is a shortcoming, though. LCPs are immiscible (incapable of mixing) with most thermoplastics at the molecular level. Fortunately, this can be overcome by the incorporation of carbon nanotubes (CNT), which not only enhances the compatibility between the LCP and thermoplastic but also improves the electrical conductivity and mechanical properties of the blend system. The challenge is that multi-walled carbon nanotubes (MWNTs) tend to form agglomerates and it is difficult to obtain uniform dispersion in the polymer blends.

Vivek R, a researcher with the IITB-Monash Research Academy, is therefore working on a project to make LCPs more productive and efficient.

The IITB-Monash Research Academy is a pioneering joint-venture research partnership between the leading institutions in India and Australia. The Academy, as it is commonly referred to, offers research scholars the opportunity to study for a dually-badged PhD from both IIT Bombay in India and Monash University in Australia. Students spend time at both countries over the course of their research and many of them work on projects that are strongly-interdisciplinary in nature and with an applied research focus.

Keeping in mind the tendency of carbon nanotubes to form agglomerates and the difficulty in achieving uniform dispersion in the polymer blends, Vivek's project is titled, 'Ternary polymer blends involving self-reinforcing liquid crystalline polymer fibrils containing carbon nanotube reinforcement'.

Fig. 2: Polymer pellets and multi-walled carbon nanotubes are melt mixed in a conical twin screw micro-compounder. The extruded strands and the injection moulded samples are then characterised using various techniques such as microscopic analysis, thermal stability studies, electrical conductivity measurements and rheological measurements. (Courtesy:Current Advances in the Carbon Nanotube/Thermotropic Main-Chain Liquid Crystalline Polymer Nanocomposites and Their Blends', Polymers, , Vol. 4, 889-912, 2012 )

Vivek is working on incorporating multi-walled carbon nanotubes into LCPs and LCP blends to create a 'network-like' structure of MWNTs within the polymer matrix. The formation of the 'network-like' structure could result in the improvement of the mechanical and electrical properties of the resulting blends and composites.

Vivek says, "This project aims to develop new blends of self-reinforcing ternary polymer blends involving an engineering plastic matrix—liquid crystalline polymer fibrils which are reinforced by conductive, rigid carbon nanotubes."

Prof Murali Sastry, CEO, IITB-Monash Research Academy, is convinced that researchers like Vivek and his cohorts will make a big impact in the days to come. "As the reputation of the IITB-Monash Research Academy begins to grow and as more organizations start collaborating with the Academy, we anticipate that it will contribute to maintaining India's reputation as a leading-edge global research hub," he says.

Nothing would make Vivek happier.

Research scholar: Vivek R, IITB-Monash Research Academy

Project title: Ternary polymer blends involving self-reinforcing liquid crystalline polymer fibrils containing carbon nanotube reinforcement

Supervisors: Prof. Arup R. Bhattacharyya (IITB Supervisor), Prof. George P. Simon (Monash Supervisor)

Contact details: vivekr@iitb.ac.in

This story was written by Mr Krishna Warrier based on inputs from the research student and IITB-Monash Research Academy. Copyright IITB-Monash Research Academy.