Dielectric Cure Monitoring Applications
When working on a new thermoset, the cure process is essentially unknown. What happens when the material is heated? When is the best time to apply pressure? How fast does the material react at different temperatures? Dielectric Analysis (DEA) complements more conventional thermal analysis techniques of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) to bridge the gap between laboratory and manufacturing environments.
Ion Viscosity and Its use in DEA
Dielectric cure monitoring, also known as DEA, measures a polymer’s resistivity (r) and permittivity (e’), which are the material’s dielectric properties. In general, resistivity provides the most useful information about cure state.
Guidelines for Dielectric Cure Monitoring
Although the method of DEA is simple—place a sample on the sensor, heat and start data acquisition—care and good practice are very helpful for making good measurements. Here are some guidelines for successful dielectric cure monitoring.
Distributed Dielectric Cure Monitoring of Composite Aerospace Structures
Distributed Dielectric Cure Monitoring (D-DEA) is a new concept for the application of Dielectric Analysis (DEA) in manufacturing. Instead of a single expensive base instrument and many long extension cables, D-DEA uses multiple inexpensive instruments connected along a single RS-485 communications line.
Distributed Dielectric Cure Monitoring of Wind Turbine Blades
Distributed Dielectric Cure Monitoring for the first time allows the use of DEA to monitor many locations in very large structures like wind turbine blades and composite beams. Distributed Dielectric Cure Monitoring also avoids the tangle of extension cables used for monitoring parts requiring multiple sensors, such as aircraft and spacecraft components.
Electrode and DC Resistance Cure Monitoring
Dielectric cure monitors measure the electrical properties of a thermoset with AC signals across a range of frequencies. Measurement of resistance with DC methods can also reveal information about a material, but has disadvantages and limitations that the user must consider.
Equipment for Dielectric Cure Monitoring
Dielectric cure monitors measure the dielectric properties of material at a single frequency or across a range of frequencies, selectively revealing the influence of mobile ions and dipole rotation. Ion viscosity of a material is frequency independent resistivity (rDC) and is often proportional to the change in mechanical viscosity before gelation and proportional to the change in modulus after gelation. Consequently, ion viscosity is a useful probe of material state through the entire cure.
LT-439 Dielectric Channel: A Simpler Tool for Cure Monitoring in QA and Manufacturing
Available now, our LT-439 Dielectric Channel is a low-cost, compact instrument designed for cure monitoring in quality control/quality assurance and manufacture of thermoset materials such as resins, composites, paints, and coatings. The LT-439 will accept all Lambient Technologies dielectric sensors, and most other dielectric sensors. Measurements from the LT-439 may be interfaced to any control network through its RS-485 serial port. Each LT-439 supports one dielectric sensor and one thermocouple but up to 256 individual dielectric channels can be connected on a single RS-485 line. This flexibility eliminates complex cabling and allows simultaneous, multi-channel cure monitoring of material state at any point in a large part. When used with the optional CureView software and disposable or reusable dielectric sensors, the LT-439 Dielectric Channel interface becomes a complete system for dielectric cure monitoring in all processing environments.
LTP-250 MicroPress: A Portable, Easy-to-Use Testing Solution
Available now, the LTP-250 MicroPress is a miniature thermal pneumatic press designed for the curing of SMC, BMC, epoxies, polyesters, polystyrenes, polyurethanes, silicones, laminates and other polymeric materials. Providing a portable, easily operated platform to reproduce the time-temperature-pressure processing profiles of most polymers, the LTP-250 MicroPress has independent temperature control of both upper and lower platens and can operate in either isothermal or ramp-and-hold modes.The LTP-250 MicroPress can be controlled manually or with the Lambient Technologies CureView software. When used with any of the Lambient Technologies dielectric sensors, the LTP-250 MicroPress becomes a complete testing station for dielectric cure studies.
Do you have a need for an in-situ cure monitor for a thermoset process but don’t know where to start? Are confused about the terminology used in dielectric spectroscopy? Don’t know how the dielectric response is related to the viscosity change during curing? Interested in understanding how dielectric spectroscopy can monitor curing? Would you like to see real-world examples of how the viscosity and dielectric loss factor or ion viscosity are used in cure monitoring?
Lambient Technologies continues to assert itself as experts in the field of Dielectric Analysis with the release of "The Handbook of Dielectric Analysis and Cure Monitoring". To see a listing of contents and to download the Handbook, please go to the Downloads page. Click Here
Lambient continues to expand representation world-wide by partnering with FullTech in Italy.Read more about FullTech.
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Focus on DEA. Click below for the most recent material report.Cure Monitoring of Polyurethane
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Dr. Gotro hosts the Polymer Innovation Blog. In his blog, he shares some of his experiences, tips, and “tricks of the trade” to get more out of your innovation efforts and discusses new trends and technical advances in the polymer industry. Here are some of Dr. Gotro's recent discussions regarding Dielectric Cure Monitoring.• Part 1: Background
• Part 2: Relationships Between Dielectric Measurements and Curing
• Part 3: Isothermal Curing
• Part 4: Non-Isothermal Curing
• Part 5: Simultaneous Measurement of Viscosity and Dielectric Loss Factor
• Part 6: Simultaneous Viscosity and Dielectric Loss Factor Measurements
• Part 7: Dipoles in Action
• Part 8: An Interesting Experiment
• Part 9: Lamination Process Monitoring
• Part 10: What does dielectric cure monitoring measure?
• Part 11: Identifying Ion Viscosity
• Part 12: Dielectric Sensors
• Part 13: Equipment for Dielectric Cure Monitoring
• Part 14: Cure Monitoring of SMC and BMC Molding
• Part 15: Cure Monitoring of Carbon Reinforced Prepreg
• Part 16: Do's and Dont's for Dielectrtic Cure Monitoring