RESUMEN
A stretching apparatus capable of conducting tensile tests over a broad strain rate range (10-3-250 s-1) and a wide temperature range (-75-250 °C) has been designed for polymeric materials, in particular the polymeric films. Specifically, this stretching apparatus can be combined with in situ ultrasmall-, small-, and wide-angle x-ray scattering (USAXS/SAXS/WAXS) measurements. The sample stretching is achieved through the synchronized rotation of rolls, powered by servo motors. The output electrical signal extracted from a torque sensor, when combined with the rotational speed of rolls and initial sample dimensions, enables the determination of the relationship between engineering stress (σ) and Hencky strain (ε). With the sample chamber and precise control loop, the prescribed temperature can be achieved using either hot airflow for heating or cold liquid nitrogen flow for cooling. By integrating this stretching apparatus with a high brilliance x-ray source at beamline BL10U1 in Shanghai Synchrotron Radiation Facility (SSRF) and detectors featuring ultrafast acquisition rates, it becomes possible to monitor multiscale structure evolutions of polymeric samples under harsh conditions involving high-speed loading combined with varying temperatures.
RESUMEN
A steel belt casting equipment, weighing approximately â¼6-7 tons and measuring â¼5 m in length, has been designed and developed for simulating the industrial processing of polymer films and being combined with synchrotron radiation in situ x-ray scattering measurements. Through modification of its modules, it is feasible to implement two distinct film casting modes, namely the wet and the dry casting processes. The speed of a steel belt can span from 0.5 to 8 m/min. The highest experimental temperature and drying wind speed are 300 °C and 6 m/s, respectively. All film casting parameters, such as extrusion speed, distance between die and steel belt, casting speed, temperature, and wind speed, can be adjusted independently. Especially, the control accuracy of the temperature and casting rate can reach ±0.1 °C and ±0.01 m/min, respectively. The feasibility of this equipment has been validated through in situ x-ray scattering tests at the BL10U1 industrial beamline of the Shanghai synchrotron radiation facility. With the assistance of this equipment, the understanding of the physical mechanism behind the film casting process should be improved so that the development of advanced functional polymer films.
RESUMEN
A biaxial stretching device is designed and developed for the real-time structural measurements of polymer films. This device adopts a vertical layout to perform real-time x-ray scattering measurements. It has a maximum stretching ratio of 8 × 8 in two perpendicular directions. Its maximum experimental temperature and stretching rate are 250 °C and 100 mm/s, respectively. The control accuracies of the experimental temperature and stretching rate are ±1 °C and 0.01 mm, respectively. All the parameters related to film biaxial processing, such as stretching speed, stretching ratio, and temperature, can be independently set. The device feasibility is demonstrated via a real-time experiment in a synchrotron radiation beamline. Wide-angle x-ray diffraction, small-angle x-ray scattering, and stress-strain data can be simultaneously obtained during various stretching modes. The proposed device fills the gap between the synchrotron radiation x-ray scattering technique and the biaxial stretching processing of polymer films. This device will play an important role in improving the understanding of the physics behind biaxial polymer processing.