REAL-TIME ANALYSIS OF ETHYLENE-VINYL ACETATE RANDOM COPOLYMERS USING NEAR-INFRARED SPECTROSCOPY DURING EXTRUSION

Poly(ethylene vinyl acetate) (EVA) is a very common polymer used in ho t melt adhesives. The rheological and thermal-mechanical properties of these adhesives are strongly related to the content of vinyl acetate (VA) incorporated into this random copolymer during polymerization. Re sults of in-line monitoring of VA content in flowing molten EVA polyme rs, using fiberoptic near infrared spectroscopy, shall be discussed in detail. In-line monitoring is not only desired for its numerous advan tages (such as high quality products, lower waste, lower developmental cycle time, and lower costs) but also because it eliminates the sampl e handling concerns associated with molten polymers.