Refractive index cellulose polymer

GAO Gao, W., Liu, X.M., and Gross, R.A., Determination of molar mass and solution properties of cationic hydroxyethyl cellulose derivatives by mrrlti-angle laser light scattering with simultaneous refractive index detection, Polym. Int., 58, 1115, 2009. 

Kandelaki S.A. PhD thesis Diffusion formation of the gradient of refractive index in polymer media based on diallyl monomers. Leningrad Cellulose-paper Technological Institute, Leningrad, 1989 [In Russian]. 

Transparent Polymers. Amorphous thermoplastics, like poly (methyl methacrylate), polystyrene, SAN, PVC, or the cellulose esters are transparent and used for glazing, photographic film, blown bottles, or clear packaging containers. Only a few crystalline thermoplastics, like poly (4-methyl-l-pentane), where the crystalline and the amorphous phases have almost identical refractive indexes, or polycarbonate, which has smaller crystals than the wavelength of light, are also transparent. R. Kosfeld and co-workers analyzed the mobility of methyl groups in polycarbonate, poly (methyl methacrylate) and poly( -methyl styrene) by NMR spectroscopy. 

Cotton fibers are single cells composed primarily ( 96%) of the polymer cellulose. In our laboratory (5), cotton fibers were dissolved directly in the solvent DMAC-LiCl. This procedure solubilizes fiber cell wall components directly without prior extraction or derivatization, processes that could lead to degradation of high MW components. MW determinations have been carried out by a size-exclusion chromatography (SEC) system using commercial columns and instrumentation with DMAC-LiCl as the mobile phase. Incorporation of viscometry and refractive index (RI) detectors (6) allowed application of the universal calibration concept (7) to obtain MW distributions (MWDs) based on well-characterized narrow-distribution polystyrene standards (5). The universal calibration concept used by incorporation of dual detectors bypasses the need for cellulose standards. There are no cellulose standards available. Polystyrene standards for a wide range of MWs dissolved readily in DMAC-0.5% LiCl with no activation necessary. 

Many cellulose derivatives form lyotropic liquid crystals in suitable solvents and several thermotropic cellulose derivatives have been reported (1-3) Cellulosic liquid crystalline systems reported prior to early 1982 have been tabulated (1). Since then, some new substituted cellulosic derivatives which form thermotropic cholesteric phases have been prepared (4), and much effort has been devoted to investigating the previously-reported systems. Anisotropic solutions of cellulose acetate and triacetate in tri-fluoroacetic acid have attracted the attention of several groups. Chiroptical properties (5,6), refractive index (7), phase boundaries (8), nuclear magnetic resonance spectra (9,10) and differential scanning calorimetry (11,12) have been reported for this system. However, trifluoroacetic acid causes degradation of cellulosic polymers this calls into question some of the physical measurements on these mesophases, because time is required for the mesophase solutions to achieve their equilibrium order. Mixtures of trifluoroacetic acid with chlorinated solvents have been employed to minimize this problem (13), and anisotropic solutions of cellulose acetate and triacetate in other solvents have been examined (14,15). The mesophase formed by (hydroxypropyl)cellulose (HPC) in water (16) is stable and easy to handle, and has thus attracted further attention (10,11,17-19), as has the thermotropic mesophase of HPC (20). Detailed studies of mesophase formation and chain rigidity for HPC in dimethyl acetamide (21) and for the benzoic acid ester of HPC in acetone and benzene (22) have been published. Anisotropic solutions of methylol cellulose in dimethyl sulfoxide (23) and of cellulose in dimethyl acetamide/ LiCl (24) were reported. Cellulose tricarbanilate in methyl ethyl ketone forms a liquid crystalline solution (25) with optical properties which are quite distinct from those of previously reported cholesteric cellulosic mesophases (26). 

SEC-LS is used to measure molecular weight distribution directly as a polymer elutes from the SEC without universal calibration. For each polymer-solvent system, the specific refractive index increment dn/dc is required, and for most instruments the solvent refractive index is also needed. Table 3 lists selected papers describing SEC-LS measurements of synthetic polymers, copolymers, polysaccharides, cellulosics, and related polymers. 

Size-exclusion chromatography (SEQ and gel permeation chromatography (GPC) are very important tools in polymer characterization. They can provide the answers to key properties in polymer materials such as starches, cellulosics, nylon, polyethylene, PET, etc. GPC instruments are equipped with columns for aqueous or organic mobile phases. A refractive index detector is a very popular detector for most GPC applications. SEC (or GPC ) is used to chromatographically separate polymer molecules by size... 

C to - -3°C saponification value, 186-194 iodine value, 99-98 refractive index, 1.4625-1.4645 (40°C). (Bailey s industrial oil and fat products. Shahidi F, Bailey AE (eds). Wiley, New York, 2005 Paint Pigment, drying oils, polymers, resins, naval stores, cellulosics esters, and ink vehicles, vol 3. American Society for Testing and Material,... 

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