GENERAL >IICK()SCOPY 



Table 1. Birefringence Values of 

 Principal Fibers 



fibroscopes. In projection they give a con- 

 stant magnification of about 700 X. Measur- 

 ing tables are supplied with this instrument, 

 which permit rapid determination of fiber 

 thickness. 



The phase contrast and interference micro- 

 scopes are used for structural investigation. 

 This method can be recommended mainly 

 for longitudinal and cross sections. Especially 

 with the interference methods it is possible 

 to observe and measure even minute refrac- 

 tive index differences in the fibers. 



Birefringence measurements of fibers are 

 very important both for fiber identification 

 and for structural investigation. These meas- 

 urements can be made with a polarizing 

 microscope with the aid of a capillary ro- 

 tator. Very accurate measurements can also 

 be made with the immersion method. 



The average birefringence values for a 

 number of fibers are listed in Table 1. 



Fibers are rather seldom subjected to a 

 fluorescent microscopic examination. The 

 fluorescence inherent in most fibers differs 

 only slightly and is moreover fairly weak. 

 The method can be successfully employed, 

 however, in examining cotton for mcrceriza- 

 tion. These fluorescent colors may be im- 

 portant in conjunction with other data. In 

 some cases the use of fluorochromes has pro- 

 vided important data. In the case of wool, 

 for instance, the nature of damage can be 

 demonstrated very well by staining with a 

 mixture of Rhodanine 6 GD and Coriphos- 

 phine. 



Data so far obtained do show that fluores- 

 cence investigation is definitely useful for 

 fiber microtechnology. 



Both electron and x-ray microscopy are 

 widely used for fiber research. They are of 

 great importance especially for more funda- 

 mental structural investigation. Investiga- 

 tions are made with replicas, thin sections 

 and breakdown products. In surface exami- 

 nation, good results have already been ob- 

 tained with the electron scanning micro- 

 scope. It appears that this method, together 

 with x-ray microanalysis and ion etching is 

 going to be very important in fiber research. 



Techniques of Fiber Microscopy 



The technical part of fiber microscopy can 

 be divided into: preparation methods, stain- 

 ing methods, mounting methods and micro- 

 scopic techniques. Most of the preparation 

 techniques can be used for examining all 

 types of fibers, but this is not the case with 

 staining methods. Subdivision according to 

 the nature of the fibers is necessary. 



Preparation Techniques. Making 

 Cross-sections. Three methods are employed 

 for making cross-sections. 



(1) Plate Method. A bunch of fibers is 

 pushed through a 0.5-mm hole in a 0.5-mm 

 thick copper plate. The opening must be well 

 filled so that the fibers are tightly packed. 

 The fibers are severed on both sides with a 



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