Quantitative analysis copolymers

Stribeck N, Fakirov S and Sapoundjieva D (1999) Deformation Behavior of a Poly(ether ester) Copolymer. Quantitative Analysis of SAXS Fiber Patterns, Macromolecules 32 3368-3378. 

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. 

As the majority of stabilisers has the structure of aromatics, which are UV-active and show a distinct UV spectrum, UV spectrophotometry is a very efficient analytical method for qualitative and quantitative analysis of stabilisers and similar substances in polymers. For UV absorbers, UV detection (before and after chromatographic separation) is an appropriate analytical tool. Haslam et al. [30] have used UV spectroscopy for the quantitative determination of UVAs (methyl salicylate, phenyl salicylate, DHB, stilbene and resorcinol monobenzoate) and plasticisers (DBP) in PMMA and methyl methacrylate-ethyl acrylate copolymers. From the intensity ratio... 

Applications Applications of SEC-FTIR include quantitative analysis of copolymers [701] product deformulation of hot melt adhesives characterisation of polymer compositional heterogeneity analysis of complex mixtures of urethane oligomers and eventually also the identification and quantitative analysis of polymer additives... 

The literature reports various (multidimensional) chromatographic approaches involving SEC and LC operating on dissolved polymer/additive mixtures. Floyd [985] has used microbore (1 mm i.d.) SEC-RPLC for the quantitative analysis of Tinuvin P in a cellulose acetate solution in THF, after separation of the polymeric and additive fractions total analysis time about 30 min. Relative accuracy and precision of 3 % and 1.5% were quoted. SEC-RPLC was also used to determine the styrene level in polystyrene crystals [986]. Additives in copolymers have been separated in a SEC/C system [987]. Chlorohydrin mixtures may be analysed by RPLC, but not in the presence of polymer. Thus, SEC... 

F.C. Y.Wang and P.B. Smith, Quantitative analysis and structure determination of styrene/ methyl methacrylate copolymers by pyrolysis gas chromatography, Anal. Chem., 68, 3033 3037(1996). 

SN2 reactions of primary organolithium compounds on PMMA in dilute homogeneous solution may be considered as a model system where all the important reaction parameters may be controlled they allow both a quantitative analysis of PMMA chain reactivity and the synthesis of well defined ketonic copolymers within a wide range of possible structural variations. The two homologous series of organolithium compounds and the corresponding reaction conditions we selected are given below ... 

Unit distribution in the substituted PMMA (35) was investigated by two independant methods a) Direct analysis of copolymer microstructure by H-NHR at 250 MHz the NMR spectrum (pyridine solution at 80°C) are sufficiently well resolved to allow a quantitative analysis of unit distribution, in terms of A centered triads and isolated B units in ABA triads, b) UV studies of the ionization and of the intramolecular cyclization of the B B and B B dyads in protic basic media (Na0H-H 0 O.IN, NaOMe-MeOH O.IN) in such a medium the partially ionized copolymer chains are the site of a complex series of consecutive intramolecular reactions we have completely elucidated (35). The first step is of interest with respect to B unit distribution ... 

In the characterization of copolymers one distinguishes between qualitative analysis, designed to test whether the material is a genuine copolymer or only a physical mixture of homopolymers, and quantitative analysis of the weight fraction of the incorporated comonomers. 

Quantitative analysis of copolymers is relatively simple if one of the comonomers contains a readily determinable element or functional group. However, C,H elemental analyses are only of value when the difference between the carbon or hydrogen content of the two comonomers is sufficiently large. If the composition cannot be determined by elemental analysis or chemical means, the problem can be solved usually either by spectroscopic methods, for example, by UV measurements (e.g., styrene copolymers), by IR measurements (e.g., olefin copolymers), and by NMR measurements, or by gas chromatographic methods combined with mass spectroscopy after thermal or chemical decomposition of the samples. 

The diode array UV/vis spectrophotometer was used to both Identify the polymer exiting and to obtain a quantitative analysis of the copolymer composition distribution. Figure 9 (6) shows the result of summing many individual fraction analyses to see the total copolymer composition distribution. The result had the correct average composition but not the skewed shape expected from theory. Part of the difficulty was the relatively small number of cross fractionations done. 

Fig. 1 shows the increase of nitrite band near 780 cm- for various alcohol contents in ethylene-vinyl alcohol copolymers. The analysis of the hydroxyl region of the IR spectra (not shown) indicated that the reaction was not quantitative (residual OH band). The precise analysis of this band ( 34(X) 70 I / mol. cm) as w ell as the nitrite band (e780 639 I / mol. cm) allows to evaluate the reaction yield considering the total film thickness (Transmission 1R). The values decrease when the OH content increases (0.75 0.62 0.59 ans 0.59 for vinyl alcohol contents 2.6,4.9, 7.7 and 10.1% respectively). Complementary analysis by reflexion IR (HATR) showed that the first 5-8 pm (Germanium crystal) were fully transformed while the analysis of the first 20-25 pm (Zinc Selenide crystal) revealed a decrease of the yield from 1 to 0.5 when the alcohol content was increasing. Then, this treatment can be helpfull for surface modification of membranes. 

This conclusion is also supported by a quantitative analysis of the strength of the dielectric f3 relaxation, expressed through the change of permitivity, fy determined from the frequency response. Indeed, at 23 °C, sf is consistent with the amount of ester groups present in the CMIMx copolymer, whereas at 98 °C, s is much weaker than expected from the ester content, showing that CMI units hinder cooperative jr-fiip ester motions. 

Using the calculational method based on DDFT, deviations from the cylinder bulk morphology have been identified as surface reconstructions [58, 62], The constructed structure or phase diagrams allowed surface field and confinement effects to be distinguished [57-59, 107, 145, 186], The comparative analysis of defect types and dynamics disclosed annihilation pathways via temporal phase transitions [36, 111]. Further, a quantitative analysis of defect motion led to an estimate of the interfacial energy between the cylinder and the PL phases [117]. A DDFT-based model was effectively used to simulate a block copolymer film with a free surface and to study the dynamics of terrace development [41,42], We showed how our computational method and an advanced dynamic SFM can be exploited in a synergetic fashion to extend the information about the elementary steps in structural transitions at the mesoscopic level. In particular, the experiments validate the dynamic DDFT method, and the DDFT calculations rationalize the characterization of the film surface in the interior of the film [187],... 

The application of refractive index and differential viscometer detection in SEC has been discussed by a number of authors [66-68]. Lew et al. presented the quantitative analysis of polyolefins by high-temperature SEC and dual refractive index-viscosity detection [69]. They applied a systematic approach for multidetector operation, assessed the effect of branching on the SEC calibration curve, and used a signal averaging procedure to better define intrinsic viscosity as a function of retention volume. The combination of SEC with refractive index, UV, and viscosity detectors was used to determine molar mass and functionality of polytetrahydrofuran simultaneously [70]. Long chain branching in EPDM copolymers by SEC-viscometry was analyzed by Chiantore et al. [71]. 

Both approaches are accomplished isocratically and therefore the problem of irreproducible gradient production, which is a limitation for the quantitative analysis of copolymers by gradient chromatography, is avoided. 

Py-GC/MS can be applied for both qualitative and quantitative purposes. One typical use of quantitative analysis using pyrolysis is the determination of the amount of a specific polymer in a given complex matrix, such as a composite material, inorganic matrix, etc. Since solubilization is frequently a very difficult task for these materials, pyrolysis can provide quantitative information based on the level of the polymer marker generated by the thermal decomposition. Calibration is typically necessary in these situations, and similarly to other analytical procedures this can be achieved using a standard addition type procedure (see e.g. [17]) or a calibration with known amounts of polymer in a similar or identical matrix. Another case where the quantitation can be necessary is the determination of the amount of a comonomer in a copolymer sample. Successful quantitation by Py-GC/MS is reported in literature for various copolymers [25-39], etc. 

Rapid, accurate analysis of copolymer products is critical to the efficiency and economy of modern industrial copolymer production. Infrared spectroscopy is a well established technique for both qualitative and quantitative analysis of polymeric materials (1, 2). However, the coupling of relatively low-cost data handling hardware and software to a microprocessor-controlled infrared spectrophotometer is a relatively recent development. This coupling considerably enhances the level of performance one can expect from quantitative infrared spectroscopy. The result is that such systems greatly reduce the effort, expense, and time required for a given analysis and simultaneously provide improved accuracy, reliability, and precision. This paper will describe a recently developed, commercially available software system which will be referred to hereafter as QUANT. In the course of application research with the QUANT software a wide variety of copolymer systems... 

Key,L.C., Trent,F.M., Lewis,M.E. Quantitative analysis of ethylene-propylene copolymers by infrared spectrometry. Appl. Spectrosc. 20, 330-332 (1966). 

Separations of HEMA-AMPS Copolvmers. Isotachopherograms were obtained on copolymers synthesized with HEMA-AMPS monomer feed ratios (wt.) of 78/22, 60/40, 40/60, and 80/20. Copolymer samples prepared at 60/40 and 40/60 monomer ratios were phase separated and 2ure referred to as upper and lower phases. The phases are treated separately for quantitative analysis, but were recombined In dilute solution for the analysis of a copolymer mixture by ITP that Is described In a later section. 

The range of pyrolysis products is a function of the composition and structure of the pyrolysed sample, which accounts for the applicability of Py—GC in quantitative analysis and structural studies. Determining the composition of polymer systems (mixtures and copolymers) and establishing the structure of the analysed polymers are practically important and complex problems. Py—GC is used successfully in solving these problems and is one of the few methods that can be employed in investigating insoluble polymers. 

---