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Rheo-optics with the SER

Because the deformation field occurs in a fixed plane with the SER Universal Testing Platform, rheo-optics and birefringence measurements can be made on materials exhibiting birefringent behavior during the deformation process. Although operation of the SER can be coupled with any number of sophisticated laser, or electromagnetic radiation techniques, a simple white light source, a pair of linear polarizer optical filters, and a camera with video capturing capability is all that is needed in order to characterize the rheo-optical behavior of materials undergoing deformation on the SER. For instance, the simple experimental setup shown below depicting a model SER-HV-P01 mounted on an Anton Paar MCR host rotational rheometer system was used to capture the rheo-optical behavior of an uncured butyl rubber undergoing extensional deformation at room temperature. Such measurements are facilitated by the fact that butyl rubber has a fairly high stress optical coefficient at room temperature. Similar measurements can also be made for polymer melts within an oven chamber.

Rheo-optics Setup - Room Temperature

Note that for all of the SER videoclips depicted below, the sample deformation remains in a fixed plane and is ALWAYS clearly and easily accessible for flow and deformation visualization, which makes in-situ rheo-optical measurements possible during sample deformation.

Rheo-optics with Butyl Rubber

Rheo-optics with ambient lighting Rheo-optics with Ambient Lighting This rheo-optics video depicts the uniaxial extensional flow deformation of a butyl rubber at 23C being stretched at a Hencky strain rate of 0.3 s-1 with no back light source, just linear polarized ambient light passing through the mid-section of the sample. Note how the entire flow field can be visualized.
(AVI file format: 1.55 MB)
Birefringence Video Birefringence Video This rheo-optics video depicts the uniaxial extensional flow deformation of a butyl rubber at 23C being stretched at a Hencky strain rate of 0.3 s-1 with a linear polarized halogen white light passing through the mid-section of the sample. Note the uniform color evolution in the sample, evidence of the uniformity of the applied extensional deformation.
(AVI file format: 0.31 MB)
Rheo-optics During Sress Relaxation Stress Relaxation This rheo-optics video depicts stress relaxation of a butyl rubber at 23C after being stretched at a Hencky strain rate of 0.3 s-1 for a total applied Hencky strain of 2.5. Note how the stress fringes depict how the web of the sample relaxes non-uniformly from the center of the sample towards its edges as it attempts to recoil from the applied deformation.
(AVI file format: 2.46 MB)
Bubble Void Bubble Void This rheo-optics video depicts stress relaxation of a butyl rubber sample with a small entrapped bubble void in its center at 23C after being stretched at a Hencky strain rate of 0.3 s-1 for a total applied Hencky strain of 1. Note the stress fringe evolution around the bubble and how the bubble size remains stable during relaxation.
(AVI file format: 2.37 MB)
Bubble Instability Bubble Instability This rheo-optics video depicts stress relaxation of a butyl rubber sample with an identical entrapped bubble void as the sample above at 23C after being stretched at a Hencky strain rate of 0.3 s-1 for a total applied Hencky strain of 2. Note how a critical strain is surpassed thereby driving bubble instability of the entrapped void and the eventual cleaving of the sample.
(AVI file format: 1.97 MB)

Rheo-optics with Solid HDPE

Rheo-optics and Tensile Testing Rheo-optics and Tensile Testing This rheo-optics video depicts tensile elongation of a solid LLDPE sample at 23C stretched at a Hencky strain rate of 0.1 s-1 all the way to rupture.
(AVI file format: 3.44 MB)

Rheo-optics with Polymer Melts

With the use of a white light source, a fiber optic portal into the oven, and a high temperature linear polarizer optical filter, rheo-optics measurements can also be made on polymer melts within an oven chamber. For instance, the simple experimental setup shown below depicting a model SER-HV-P01 mounted on an Anton Paar MCR host rotational rheometer system equipped a CTD600 oven was used to capture the following rheo-optics videos utilizing a reflector on the end of a fiber optic cable to reflect white light off of the internal back surface of the oven enclosure and a high-temperature linear polarizer filter mounted on the back side of the SER that was used to polarize white light passing through the deforming sample and out the optical window of the oven to the linear polarizer mounted on the video camera located outside of the oven. The following videos depict parallel polarized light passing through the polymer melt samples undergoing stretch.

Rheo-optics Setup - Polymer Melts in an Oven

Rheo-optics and Flow Induced Crystallization

Rheo-optics with Polymer Melts Melt Rheo-Optics This rheo-optics video depicts the uniaxial extensional flow deformation of a molten HDPE sample at a temperature of 129C (just 0.8C below its peak melt temperature) stretched at a Hencky strain rate of 0.3 s-1. Note how the polymer sample remains perfectly clear during the entire deformation, evidence that the sample is still molten. The type of ductile fracture is also consistent with typical molten polymer behavior.
(AVI file format: 0.65 MB)
Flow Induced Crystallization Video Rheo-optics During Flow Induced Crystallization This rheo-optics video depicts the uniaxial extensional flow deformation of the same molten HDPE sample as above at a temperature of 128.5C (just 0.5C cooler than the sample above) stretched at a Hencky strain rate of 0.3 s-1. Note how the polymer sample becomes a bit cloudy immediately upon deformation and gets darker as the deformation continues, evidence of a quiescent flocculation of crystallites followed by a crystallization density increase with increasing deformation. The state of the polymer sample is definitely solid-like as witnessed by the type of fracture observed.
(AVI file format: 0.77 MB)

The SER Advantage

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