PRESERVATION OF SPECIMENS IN PLASTICS 



39 



Removal of inhibitor by alkali extraction.— In removing hydroquinone 

 or similar polymerization inhibitors by alkali extraction, the methacryl- 

 ate monomer is shaken in a separatory funnel (fig. 11) first with a weak 

 aqueous solution of sodium hydroxide and then with distilled water, 

 after which it is dried over a desiccant to remove any retained wash 

 water. 



The procedure for this operation comprises the following steps: 



1 . After making sure that the glassware is clean and entirely free from 



grease or other substances that might cause discoloration of the plastic, 



set up the apparatus in a fume hood or other enclosure where all escaping 



vapor will be effectively prevented from diffusing into the room. It is 



BHft 



Figure 11. — A separator}' funnel is used when removing inhibitor by the alkali- 

 extraction method. The operation should be carried out under a fume hood. . 



