Staining methods chlorosulfonic acid method

Peterlin et al. [157] described the use of iodine vapor, at 60°C (24 h) to reveal the structure in PE fibrils drawn from solution grown single crystals. Andrews et al. [78] extended this method to prestaining a block of material prior to ultrathin sectioning. They showed the contrast enhancement of PE spherulites by action of the iodine. However, the iodine dissipates upon standing in air and is known to vaporize in the vacuum of the electron microscope. The chlorosulfonic acid method (Section 4.4.4) has replaced iodine staining of polyethylene. 

A general method for staining PE with chlorosulfonic acid is as follows ... 

Staining was also applied (120°C) to the crystallization of PE [121,122]. The chlorosulfonation method has been applied to bulk polymers and high modulus fibers [123-125]. Smook et al. [125] studied the fracture process of ultrahigh strength PE fibers and used the method in a unique application to show the nature of the kink bands present. Highly oriented ultrahigh molecular weight PE fibers were shown to be preferentially attacked at these kink bands when exposed to the acid for 45 min at 80°C. 

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