Branching High temperature GPC equipment generally counts with different types of detectors such as refractive index, light scattering, and viscometer, among others; using these detectors it is possible to obtain the absolute MW, and in most cases it is not necessary to construct a calibration curve. A viscometer detector also provides information about the level of branching of a polymer; in fact, using this it is possible to obtain the index of branching (g), which is defined by the following equation [28]:
g = η1 ηb
(17.3) where η1 is the intrinsic viscosity of the linear polymer and ηb is the intrinsic viscosity of the branched polymer (of the same chemical nature and same molecular weight).
Sample Preparation A small sample of polymer is weighed (10 mg) and placed in a 15-ml stainless steel vial. Then, 10 ml of 1,2,4-trichlorobenzene is added to the vial and the sample is placed in an oven at 120◦C for 3 h. A stabilizing agent, such as Irganox 1010, should be added to the solvent to avoid degradation of the polymer during the dissolution period. Once the polymer is solubilized, a stainless steel filter is placed on top of the stainless steel vial; the filter is pushed down, thus the solution is filtered; in this step, any contaminants are removed from the solution.
Branching High temperature GPC equipment generally counts with different types of detectors such as refractive index, light scattering, and viscometer, among others; using these detectors it is possible to obtain the absolute MW, and in most cases it is not necessary to construct a calibration curve. A viscometer detector also provides information about the level of branching of a polymer; in fact, using this it is possible to obtain the index of branching (g), which is defined by the following equation [28]: g = η1 ηb (17.3) where η1 is the intrinsic viscosity of the linear polymer and ηb is the intrinsic viscosity of the branched polymer (of the same chemical nature and same molecular weight).Sample Preparation A small sample of polymer is weighed (10 mg) and placed in a 15-ml stainless steel vial. Then, 10 ml of 1,2,4-trichlorobenzene is added to the vial and the sample is placed in an oven at 120◦C for 3 h. A stabilizing agent, such as Irganox 1010, should be added to the solvent to avoid degradation of the polymer during the dissolution period. Once the polymer is solubilized, a stainless steel filter is placed on top of the stainless steel vial; the filter is pushed down, thus the solution is filtered; in this step, any contaminants are removed from the solution.
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