In-line non-contact polymer rheology using inertial cavitation
A novel technique for determining non-Newtonian viscosity of polymers using laser-induced inertial cavitation and high-speed videography, providing insights into material degradation. Ideal for real-time monitoring in manufacturing processes.
Overview
This innovative technique leverages laser-induced inertial cavitation combined with high-speed videography to determine the non-Newtonian viscosity of polymers. By introducing an optically transparent window between the hot-runner and the extruder, a laser pulse creates a small bubble in the molten plastic. The bubble's growth and collapse are imaged, and these observations are input into a rheology model to infer the viscosity, which indicates the degree of material degradation. This method offers a non-contact, real-time approach to monitoring polymer properties during manufacturing.
Technical specifications
- Non-contact measurement: Utilizes single laser pulses to create microbubbles in molten polymers.
- High-speed imaging: Captures bubble dynamics with pulsed LED illumination.
- Advanced modeling: Integrates bubble behavior with temperature and molecular weight data to determine viscosity.
- Applications: Suitable for use with optically transparent/translucent polymers, such as PET, in manufacturing environments.
- Scalable setup: Initial setup includes a windowed furnace, dedicated laser, and alignment platform, with plans for extruder integration.
Technology readiness level
Currently at Technology Readiness Level 4, this technique has been applied in lab settings with transparent materials and is now moving towards in-situ validation. Future phases include developing a windowed extruder prototype for industrial applications.
About University of Michigan
The University of Michigan Department of Mechanical Engineering (U-M ME) is a world-class academic and research institution based in Ann Arbor, Michigan. The department provides comprehensive undergraduate and graduate education built upon fundamental principles such as thermal and fluid sciences, solid mechanics, dynamics, and controls. Its faculty and students engage in interdisciplinary, high-impact research across diverse domains, including advanced manufacturing, automotive engineering, robotics, energy technologies, biomechanics, and micro- and nanosystems. The department operates several fully-funded research centers and maintains strong industry relationships to drive technological innovation and solve complex engineering challenges.
By integrating top-tier academic training with hands-on, team-based design and experiential learning, the department prepares students for impactful careers in research, industry, and consulting. Its research output addresses critical global needs—such as climate change mitigation, sustainable energy, and improved human health—while fostering an environment that values innovation and collaboration. The department's mission is to make the world work better, and it is consistently recognized globally for its educational excellence and leadership in advancing the engineering profession.
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