GPC data

With the move of many large chemical companies in the United States and abroad becoming more and more global, the need to be able to compare high-quality data between various company locations becomes essential. We have addressed part of this issue, i.e., high temperature GPC data, in three ways. First, we have standardized on one type of GPC column. Second, we have implemented a quality control procedure to make sure that data stay at a high quality. Finally, we have a procedure in place to approve future batches of gel to assure that the chromatograms from batch to batch will be very comparable. 

The oligomerization of cardanol with boron trifluoride etharate as the initiator was studied in detail by Antony et al. [171]. The reaction conditions were optimized by using gel permeation chromatography as 140°C with an initiator concentration of 1%. GPC data indicate conversion of all monoene, diene, and triene components into polymer except the saturated component, indicating participation of all the unsaturated components in polymerization. It is possible that the initiation of po-... 

Elucidation of Relative Rate Constants Using GPC Data.125... 

While the effect of monomer concentration [M] on Mv of PIB has been studied by a number of workers using a ariety of initiator systems11-13, such studies have not yet been carried out using M . The objective of this phase of research was to determine the effect of [M] on M and thus to calculate relative rate constants of isobutylene polymerization from GPC data. 

Analysis of Data. Gel Permeation Chromatography (GPC) was used to determine the molecular weights and molecular weight distribution of the seed and polymers that were produced. A modified version of Smith s (31) method was used to convert the GPC data to molecular weights and molecular weight distribution. 

The concentration of polymer in the seed was determined by modification of the method of Kolthoff (30) and Uranek (29) and from the GPC data. The results agreed within 20% which was considered to be within experimental error. However, the GPC value obtained as follows was used in all subsequent calculations... 

Styrene conversion calculated by this equation and styrene conversion obtained for runs 12-15 by gravimetric methods were in good agreement. In general, the gravimetric technique was 1 to 5% points greater than conversions calculated using the GPC data. 

When carefully prepared polymer samples were available in this study, attempts were made to interpret these GPC data. However, it is felt that these data are tentative and much work is necessary before any general conclusions can be drawn about the structure of this polymer. 

EDITOR S NOTE (1) The mixing of carbon black was carried out on a two-roll mill. The dispersion of carbon black in the compounded recipes was not evaluated. (2) X-ray studies of the copolymers by the author are in progress. (3) GPC data are relative and may not be comparable to those obtained with commercial instruments. 

GPC data gave Mw/Hn ratios of approximately 2.0, as reported by Valles and Macosko (6, 7) for their similar polymers. 

Later Rytter et al. reported possible polymer chain exchange with polypropylene produced with a combination of 8 and 11 with TMA [32], The number of stereoerrors increased in the binary system at higher TMA levels. As discussed in the case of Przybyla and Fink (vida supra), pentad analysis is less compelling evidence for reversible chain transfer. In addition, the gel permeation chromatography (GPC) data showed bimodal peaks, indicating very limited reversible transfer. 

The photopolymerization of St with catalytic amount of 52 as the pho-toiniferter gave a benzene-soluble polymer that contains a styryl double bond and a DC group at the polymer chain ends. When this macromonomer-iniferter 54 was copolymerized with a second monomer in the presence of an azo initiator, the formation of a high molecular weight graft copolymer was confirmed by GPC data. The monomer iniferter 52 was also used for the preparation of photoresist polymers [189]. 

As the final products—polystyrene-h-polyivinylperfluorooctanoic ester)— form micelles in tetrahydrofuran (THF) as well as in DMF, there are not direct GPC data to characterize molecular parameter. For this reason, we employed esterification of the hydroxylated block copolymers with benzoylchloride as a model reaction to obtain a comparable product with molecular solubility that can easily be characterized by DMF-GPC. The GPC data from PSB-II—our largest and therefore most sensitive block copolymer—are summarized in Table 10.2. Results for all the other polymers are similar. 

We thank A. E. Novembre and D. A. Mixon for help with GPC data, R. G. Tarascon for initial etching studies, S. A. Heffner for assistance in obtaining low temperature DSC and S. Nakahara for transmission electron microscopy. 

According to gel permeation chromatography (GPC) data, the molecular weight of SPP increased after X-ray exposures both in air and in vacuum. The elution profiles in both cases were very similar, indicating that the coupling of APSQ and DNQ or the condensation of APSQ occurs irrespective of the ambient. 

In examining these GPC data it should be noted that the averages and the Mz/Mn ratios are meant only to convey qualitative information about scission and branching owing to the problem of GPC calibration not being for branched molecules like those being produced [8],... 

Figure 18.11 Effect of exposure in New River, AZ, on the GPC data for Spectar copolymer sheeting [10]. From Photodegradation in a copoly(ethylene/1,4-cy-clohexylenedimethylene terephthalate) with and without UV absorber, presentation given by D. R. Fagerburg at the 37th International Symposium on Macromolecules, IUPAC World Polymer Congress, Gold Coast, Australia, July 1998, and reproduced with permission of IUPAC...

With reference back to the GPC data with depth (see above), one concludes that both sets of data are quite consistent and indicate that the short wavelength(s) capable of chain scission and branching are likely also active in color formation. The longer wavelengths responsible for the deeper coloration, however, must not be capable of very much chain scission or chain branching. 

Conclusions. Table II compares some characteristics of the semicontinuous and batch techniques. According to 1H NMR and GPC data the semicontinuous technique produces polymers with well defined symmetrical end groups, while the batchy polymerization may yield once-fired and unfired chain ends. The M Mn values of polymers obtained in semicontinuous runs are close to theoretical, whereas those harvested in conventional batch polymerization exhibit broader molecular weight distributions due to changing [I] and [M], presence of once-fired and/or unfired chain ends, and insufficient reactor control. The latter circumstance may even result in bimodal distributions. 

Telomerization was effective to regulate quantitative incorporation of functional groups to one end of PIPAAm chains [7,8]. Molecular weight of the semitelechilic PIPAAm determined from GPC data was in good agreement with that determined by the end-group assay. This indicates that each macromolecule carries one amino or carboxyl end group. 

Experimental Techniques. Chromatography was performed on a Varian model 5060 HPLC equipped with a RI-3 refractive index detector. A Vista Plus Gel Permeation Chromatography (GPC) data system was used consisting of a Vista 401 chromatography data system serially connected to an Apple II microcomputer. The Vista 401 performs data acquisition and allows data storage and automations capability while all SEC data processing is performed on the Apple II by means of user-interactive GPC software for automated, on-line calibration and polymer analysis. 

Alfredson, T.V., Perry W.J., and Tallman, L., Automated GPC Data Handling for Molecular Weight Calculations of Polymers, paper presented at 1982 Pittsburgh Conference and Exposition on Analytical Chemistry and Applied Spectroscopy, March 1982, Atlantic City, NJ. 

Needless to say, processing this data in a time frame compatible with the time needed for chromatography cannot be done without the aid of a computer this is true for even the 20-minute separations of Figure 1. Since the polymer chemist working with GPC is becoming more dependent on the computer programmer, it is pertinent to include software as an integral part of the GPC data system. 

Effect of Flow Rate Errors. The effect of flow rate errors on molecular-weight averages calculated from GPC data has been... 

The above description of the process is tentative because it is based on limited data. If it is correct, the predominate structures in the PHBA-modified products have amorphous PA/AA/NPG center sections end-capped with single units or short blocks of oligomeric PHBA. Random distribution of the PHBA cannot be ruled out, but the hetero-geneiety of the products suggests that a substantial fraction of PHBA is incorporated into short blocks. The FT-IR and GPC data are consistent with the proposal that short, phenolic-tipped oligomers are the predominant structure present. The possibility that the materials are physical mixtures of oligo-PHBA and amorphous diols can be virtually ruled out on the basis of the extreme insolubility of oligo-PHBA (IJ) and of the model PHBA-benzoic acid adduct synthesized in this study. These materials separate readily from solutions and dispersions of PHBA copolymers. 

An homologous series of advancement reactions was synthesized using standard reaction conditions on a 300 gram scale. The branch concentration was increased from zero to 0.677 branches/molecule. Viscosity and gel permeation (GPC) data were obtained. Table II summarizes the results. 

From the profile of the molecular weights obtained by the use of GPC data on the acetylated derivatives, the average molecular weight was calculated. From x, y, z, and N the average molecular weight of the basic structural unit was determined, and finally the number of benzene rings per molecule was realized, and hence the number of reactive sites per molecule. 

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