Ethylene-vinyl acetate copolymers quantitative analysis

Often, PCA is used as an initial investigative technique to determine if any differences can be identified within a dataset prior to a separate classification or quantitative analysis. PC plots are similarly useful in these cases. The previously mentioned work on recyclable plastics by Allen et al. is one example of this approach. Another example is the PCA analysis of a set of ethylene-vinyl acetate copolymer samples by Shimoyama and coworkers who first identified measurable differences between Raman spectra before creating a quantitative model [45]. PCA was also used by Keen et al. to distinguish fibers for forensic applications [46]. 

A second industrial field which has often used Raman spectroscopy and PLS analysis for quantitative modeling is in the production of polymers. PLS has been used on Raman spectra to predict the density of poly(ethylene terephthalate) [3] and polyethylene [73] and Chalmers and Everall mention crystallinity measurements for polyketones [74], Similarly, Sano and co-workers presented a density study of linear low-density polyethylene using PLS and Raman spectroscopy [75]. A subset of these authors have previously shown [45] the prediction of vinyl acetate content in ethylene-vinyl acetate copolymers. PLS was used along with PCA to study the rate constants for a synthesis and hydrolysis of ethyl acetate [29]. 

Jones and McClelland have demonstrated the application of transient infrared emission spectroscopy (TIRES) to quantitative compositional analysis of ethylene-vinyl acetate copolymers. Standard errors are less than 1%. 

Ethylene-vinyl acetate copolymers were investigated by simultaneous thermal analysis and pyrolysis gas chromatography. Both devices were coupled to a mass spectrometer. Calibration with polyvinyl acetate led to sufficient accuracy in relation to the vinyl acetate content, because of the linear calibration plot. Quantitative determination of vinyl acetate was carried out at both 500 and 700 C. The calibration plot was linear provided that the mass of vinyl acetate did not exceed a critical value. 18 refs. 

Figure 4.4 Quantitative (compositional) analysis of ethylene-vinyl acetate (EVA) copolymers A, infrared transmission spectrum of a 0.1 mm-thickness EVA copolymer film B, infrared absorbance spectra (offset for clarity) of a series of EVA copolymer films of 0.1 mm thickness C, infrared transmission spectrum of an EVA (32.3%) copolymer sample, 0.25 mm thickness D, infrared absorbance spectrum of an EVA (17.2%) copolymer sample, 4 mm thickness moulding ... 

Many cable sheaths are mamrfactured from heavily filled polymers, and TGA has been foimd to be of immeasurable value in studies of such materials and some of their ingredients. The combination of the weight-loss curve, for quantitative analysis, with the derivative, for a qualitative interpretation, has been found to be particularly powerful for these applications particularly when taken together with data obtained by the other thermal methods already discussed but also with that obtained by FTIR spectroscopy. In addition the vinyl acetate content of ethylene-vinyl acetate (EVA) copolymer used in the preparation of some sheathing formulations has been measured and used as a confirmation of grade. 

Mathias, L. J. Hankins, M. G. Bertolucci, C. M. et al. Quantitative Analysis by FT-IR Thin Films of Copolymers of Ethylene and Vinyl Acetate, /. Chem. Educ. 1992, 69, A217-A219. 

---