Copolymers characterization

The molecular stmcture of the copolymers is also important. Molecular-weight measurements (osmometry, gpc) and functional group analysis are useful. Block copolymers require supermolecular (morphological) stmctural information as well. A listing of typical copolymer characterization tools and methods is shown in Table 6. 

The steady structure determined by the value of Kw (Fig. 1) for the entire class of carboxylic CP obtained by precipitation copolymerization is one of the most important factors determining the possibility of reversible bonding of proteins absorbed by carboxylic CP with a high sorption capacity [16,19]. Thus, for the MA-HHTT system (Fig. 2), a complete desorption of enzyme is carried out on crosslinked copolymers characterized by low Kw values. In crosslinked structures exhibiting looser structure (Kw P 1), owing to the mobility of chain fragments of CP especially in the process of desorption, the macromolecules of sorbed protein are irreversibly captured as a result of a marked polyfunctional interaction. 

Most widely used is the two-dimensional combination of SEC and HPLC for copolymer characterization. The typical HPLC instrument is very similar to an SEC apparatus. While the ideal SEC separation is exclusively determined by entropy changes, in HPLC or adsorption chromatography it is assumed that no... 

Gores F, Kilz P (1993) Copolymer characterization using conventional SEC and molar mass-sensitive detectors. In Provder T (ed) Chromatography of polymers, chap 10. ACS Symp Ser 521, American Chemical Society, Washington, DC... 

Garcia-Rubio LH and Ro N (1985) Detailed copolymer characterization using ultraviolet spectroscopy. Can J Chem 63 253-63. 

Three factors are important in the development and implementation of successful control strategies for copolymerization reactors the availability of kinetic models which adequately describe the rate of polymerization and the properties of the resulting polymer as functions of the process variables, the availability of on-line instrumentation which enables rapid characterization of the copolymer throughout the reaction, and the availability of process data which allow for the constraints of the process to be built into the control strategy. This paper discusses the limitations of reported control strategies for copolymerization reactors from the viewpoint of the state-of-the-art of kinetic modeling and copolymer characterization. The critical stages in this process where considerable research effort is required are emphasized. 

The problem of copolymer characterization becomes more acute when on-line process measurements are required. Most of the process instrumentation available yields measurements which are functions of the molecular weight, copolymer composition and, in some cases, of the microstructure of the polymer molecules. Such is the case for on-line viscosimeters, densitometers, torque meters etc. Clearly, the development of copolymer characterization techniques in general and on-line instrumentation in particular requires extensive development. 

As shown in Figure 2, 13C-NMR analysis of the copolymer gave unambiguous signals of a block copolymer with two long sequences of essentially pure iPS and iPP (iPS-fc-iPP). Isotactic triads of each block were about 98%. Because of little measurable shift of peak locations, which might be interpreted in terms of the repeat unit interaction of a styrene-propylene sequence as compared with respective homopolymers, the copolymer characterized in this study is considered to be a simple mixture of the two homopolymers. But the results of successive fractionation, as discussed in the section Experimental Details, could eliminate the possibility of homopolymer mixtures. 

PA-6 (9-6) / PE (90) / HDPE-g-MA (1-4) PA + HDPE-MA extruded on TSE at 240°C followed by blow molding with 90% PE / DSC / SEM / rheology / permeation test / mechanical properties / selective solvent extraction + FTIR for PA-HDPE copolymer characterization Yeh etal., 1997... 

Polyamide / PP / Styrene Copolymer Characterization and Comments References... 

Copolymer Characterization. Copolymer compositions were determined by elemental analysis and thermal gravimetric analysis. A Perkin-Elmer TGS-2 ther-mogravimetric analyzer, programmed from ambient to 800 C in N2 and air, was used. Spectroscopic analysis of the copolymers was not as useful as elemental analysis and thermal gravimetric analysis measurements for analyzing these copolymers. Viscometric measurements were made in a solution of water and NaCl with a Contraves low-shear viscometer. 

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