GPC-MALLS

Figure 9 Scaling relationship between root-mean-square radius and molecular weight for polystyrene using GPC/MALLS. (From Wyatt, P. Hicks, D. L., Jackson, C., and Wyatt, G. K., Am. Lab., 20, 108,1988. With permission.)...

For carboxyls in cellulose the FDAM label (Scheme 17) was found to be most suitable in combination with GPC-MALLS analysis [158]. 

Gerle M, Fischer K, Roos S et al (1999) Main chain conformation and anomalous elution behavior of cylindrical brushes as revealed by GPC/MALLS, light scattering, and SFM. Macromolecules 32 2629-2637. doi 10.1021/ma9816463... 

Fig. 12. Direct measurement of molar mass (diagonal line) of a PVB sample by GPC-MALLS irrespective of the structural differences in the sample.

GPC-MALLS multiangle laser light scattering detector... 

Indeed this leads to more short-chain branches in the case of the shorter alkenylsilanes but the efficiency of the long-chain branch (polymeric branch) is higher for the longer alkenylsilanes. Thus, the gel permeation chromatography multiangle laser light scattering (GPC-MALLS)-derived LCB data indicate that the ratio of LCB to total branch content increases in the order... 

The final step in establishing the branching structure is to relate g to the branching structure. This requires some knowledge of the way the polymer was synthesized. For a number of known structures, theoretical equations have been derived. Equations 2.17 to 2.26 are examples, and Small [7] has listed sources for many others. The GPC-MALLS technique is clearly a very valuable tool in the study of branched polymers. On the one hand, it can be used to verify polymerization models, and on the other, it produces data that can be used to predict rheological properties using the models presented in Chapters 9 and 11. 

The long-chain branched metallocene polyethylenes made with the constrained geometry catalysts described in Chapter 3 pose their own special problem, because the level of branching, 0.01 to 0.1 LCB per 1,000 carbon atoms, is too low to be detected by means of GPC-MALLS. For these materials the factor j8 in Eq. 2.104 has been established to be 0.5 by use of C-13 NMR [57], and this makes it possible to use GPC-LALLS-DV to determine the distribution of radii of gyration and the number of branches per 1000 carbon atoms. Then using the results... 

Figure 2.5 Branching Index g versus molecular weight plot for eluted fractions of an LDPE determined using GPC-MALLS. = 445,000, PI = 39, and density = 0.917. Data from the two detectors give M and for each slice of the chromatogram. From Yu etal. [78].

Journal of Applied Polymer Science lA, No. 10, 5th Dec. 1999, p.2432-8 CHARACTERIZATION OF BISPHENOL A-BASED EPOXY RESINS BY HPLC, GPC, GPC-MALLS, VPO, VISCOMETRY, AND END GROUP ANALYSIS ON THE IDENTIFICATION OF 2,3-DIHYDROXYPROPYL-CONTAINEVG COMPOUNDS, DETERMINATION OF MOLAR MASS DISTRIBUTION, AND BRANCHING Podzimek S Kastanek A SYNPO... 

---