Polymer Composites

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The Industrial Materials Institute (IMI) performs R&D on processing of polymer composite systems in order to achieve optimum performance through better control of the material's microstructure.

The activities are oriented along the following themes:

• optimization of polymer composite formulations
• characterization and control of the matrix microstructure and the fibre-matrix interface
• optimization of composite forming processes
• evaluation of composites performance
• nondestructive characterization

Industrial applications

The technologies developed allow the manufacturer to optimize and control the composites' structure, i.e. fibre-matrix interactions, matrix crystallinity, degree of cure and fibre arrangement.

They also make it possible to optimize the forming processes in terms of economics, productivity, product performance, quality and reproducibility.

The developed technologies result in more productive manufacturing processes and better parts, i.e. structural profiles or moulded parts with improved stiffness, fatigue and impact resistance.
Numerous applications can benefit from these technologies:

• construction (profiles, beams, tools)
• transportation (moulded parts, body panels, fuel and gas tanks)
• aerospace (satellites and aircraft structures)
• marine (non-corrosive parts, cables)
• biomedical (dental fixtures, prosthetic devices)
• electrical/electronics (circuit boards)
• recreation industries (skis, poles, skates, boats, racket frames, snowboards)

Microstructural analysis of
PEEK/carbon fiber composite

Research activities

Optimization of polymer composite formulations

Research into the constituents and the composition of both thermoset and thermoplastic composites will lead to:

• improved thermal and environmental stability of the composites
• the optimal resin/reinforcement ratio

Control of microstructure and interfaces

Understanding and control of the material's behaviour during processing constitutes a major area for the group. This encompasses several activities:

• effects of processing parameters on the fibre/matrix interaction
• optimization of the interfacial strength by the use of sizing agent or chemically modified resin
• characterization of time-temperature-pressure effects on the matrix morphology
• characterization of time-temperature-pressure effects on defects, porosity and fibre arrangement (alignment, orientation, fibre distribution, fibre contact)

Optimization of composite forming processes

Activities in this area aim at understanding how the process parameters influence the product performance, and at controlling these parameters in order to optimize the forming processes. This also involves:

• on-line characterization of thermoset matrix curing by rheology, dielectrometry and spectroscopy.

Several processes are being examined according to the type of composite material:

• thermosets
  - autoclave moulding
  - compression moulding
  - E-beam curing
• thermoplastics
  - autoclave moulding
  - compression moulding
  - extrusion/pultrusion
  - injection moulding
  - roll forming
  - vacuum moulding
  - thermoforming-stamping

Evaluation of composite performance

This involves quantitative characterization of the composite material's behaviour as a function of micro-structural parameters:

• matrix morphology, fibre/matrix interface and fibre arrangement
• short and long term mechanical behaviour (stress-strain, fatigue, impact, fracture properties)
• environmental effects on the mechanical performance
• physicochemical characterization (thermal degradation, aging, solvent and UV radiation resistance)

Laser ultrasonic imaging of the impact damage in a graphite-epoxy plate.
Up: time-of-flight C-scan. Down: amplitude C-scan.

Nondestructive inspection

The techniques which have been developed and are available at IMI are based on the use of infrared thermographic imaging and ultrasonic imaging.

The infrared thermographic imaging system can rapidly inspect areas as large as 1 m X 1 m and reveal delaminations close to the surface.

Ultrasonic imaging uses two unique facilities:

• high precision water immersion scanning
• laser-ultrasonic inspection

The immersion scanning system allows high resolution imaging of flaws in parts smaller than 0.5 m. It has been used in particular to image subsurface matrix cracking.

The laser-ultrasonic inspection system allows to image flaws in large parts (as large as 1.5 m X 1.5 m) and of complex shapes. It allows the detection of delaminations, disbonds and other defects in laminates, honeycomb structures and bonded assemblies.

Nondestructive characterization

IMI has developed ultrasonic techniques to measure the elastic constants of composites samples. These nondestructive techniques provide more elastic parameters than conventional mechanical tests.

Research activities are currently focused on the development of ultrasonic approaches to characterize the composite and, in particular, to nondestructively evaluate fibre constant ratio, improper cure and material degradation.

Technology transfer

Companies with R&D needs can benefit from several progressive technology transfer opportunities. The work can be carried out in the form of:

• a joint project with an integrated approach which could involve other expertise available at IMI in modelling and control
• a feasibility study for process or product validation
• technical support involving specific or unique expertise or equipment

Information

To learn more about these and other technologies in order to benefit from NRC's R&D resources and give your firm a technological advantage, you are invited to contact IMI representatives.

Martin Bureau, Ph.D. Group Leader Advanced Polymer Composites Tel.: 450-641-5179 Fax: 450-641-5105 E-mail: Martin.Bureau@cnrc-nrc.gc.ca
Alexandre Paris, Eng. Business Development Officer Advanced Materials Design Tel.: 450-641-7524 Fax: 450-641-5105 E-mail: Alexandre.Paris@cnrc-nrc.gc.ca

Related Information

Institutes:

• NRC Industrial Materials Institute