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Spatially Resolved Measurements of Out Of Plane Chain Orientation and Equi-Biaxial Tension in Adhered Polymer Films by Polarized Optical Microscopy

IP.com Disclosure Number: IPCOM000108834D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 3 page(s) / 88K

Publishing Venue

IBM

Related People

Yang, AC: AUTHOR

Abstract

Due to the equi-biaxial nature of the out-of-plane chain orientation in the thermally cured polymer films adhered to a rigid substrate, the conventional photoelasticity can not apply to measure the chain orientation, and, therefore, the stress. However, with serial tilting measurements of the birefringence in a polarized optical microscope, both the chain orientation and the stress, as will be shown in the following, can be measured with an additional high spatial resolution.

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Spatially Resolved Measurements of Out Of Plane Chain Orientation and Equi-Biaxial Tension in Adhered Polymer Films by Polarized Optical Microscopy

       Due to the equi-biaxial nature of the out-of-plane chain
orientation in the thermally cured polymer films adhered to a rigid
substrate, the conventional photoelasticity can not apply to measure
the chain orientation, and, therefore, the stress.  However, with
serial tilting measurements of the birefringence in a polarized
optical  microscope, both the chain orientation and the stress, as
will be shown in the following, can be measured with an additional
high spatial resolution.

      By tilting the sample in a polarized optical microscope, as
shown in Figure 1, the birefringence wobs detected by the microscope
can be calculated from the lengths OQ and OP shown in the indicatrix
(Figure 2) to be

                            (Image Omitted)

where n1 is the refraction index perpendicular to film thickness, n2
the out-of-plane refraction index, and R the tilting angle.  Assuming
that n2 is the stress-free refraction index, the chain orientation
w1,2 = n1 - n2  can be obtained by fitting Eq. 1 with the data
of wobs measured at various tilting angles.  Multiplying the
birefringence w1,2 with the stress optical coefficient (SOC) of the
polymer yields the equi-biaxial tension maintained in the adhered
film.

      Figure 3 shows an example where a data fitting gives a chain
orientation...