Monomers analysis

Residual monomers in SAN have been a growing environmental concern and can be determined by a variety of methods. Monomer analysis can be achieved by polymer solution or directly from SAN emulsions (27) followed by "head space" gas chromatography (gc) (28,29). Liquid chromatography (Ic) is also effective (30). 

SHS-GC is amongst the best methods of choice for volatile monomer analysis and effectively gives both isolation and preconcentration of the analyte in one step. Headspace methods are used extensively for... 

Copolymer Analysis. Even though the overall copolymer composition can be determined by residual monomer analysis, it still is necessary to have reliable quantitative techniques for copolymer composition measurements on the actual copolymer, mainly because concentration detectors for SEC or HPLC are sensitive to composition and because the conversion histories are not always available. Some of the techniques used to determine copolymer composition are melt viscometry (46), chemical analysis, elemental analysis, infrared spectroscopy (IR), Nuclear Magnetic Resonance (NMR), ultra-violet spectroscopy (UV), etc. Melt viscometry, chemical and elemental analysis are general techniques that can be applied to almost any polymer. The spectroscopic techniques can be applied depending on the ability of the functional groups present to absorb at specific wavelengths. 

Table IX shows the monomer analysis of freeze dried dialysis retentate of apple juices made in the laboratory with the three technologies. It provides information on the degree of...

Fig. 20. Modified sample preparation of alditol acylate for GLC monomer analysis of O-allyl glucans. ...

Fig. 23. Monomer analysis by ESI-MS/CID of methylated glucans after perdeuteriomethylation and partial hydrolysis (according to Ref. 256).

Propylene, for example, can be polymerized to polyethylene with certain catalysts and is therefore its own comonomer. Thus, in copolymerizations with a second monomer, monomer analysis and nonspecific copolymer analysis (microanalysis, etc.) only give the incorporations, and hence r, but not the fraction of propylene/ethylene units. 

However, a comparison of the kinetic equations (3.34) and (3.36) with the experimental data shows, that they cannot quantitatively describe the process both in the autoacceleration state and in the autodeceleration states and do not agree in the section of maximal polymerization rate, since in the variant of the microheterogeneous model [2] the regularities of the polymerization at the interface layer are considered to be the same as the regularities in the volume of liquid monomer. Analysis of the experimental data shows that this assumption is not true. 

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