Spectra polyvinyl acetate

Figure 12.18. Edited DEPT 1JC spectrum of polyvinyl acetate. (Contributed by David Lankin.)...

A method of quantitatively determining 0.2% polyvinyl acetate in polystyrene has been described by Peitscher (1979) by using difference spectroscopy. Quantitative single component analysis of polymer films has been described by Chalmers et al. (1982). All samples were prepared by hot compression molding. This treatment produces a mat film surface, which suppresses interference fringes in the IR spectrum. For quantitative analysis it is essential that the thus produced films are homogeneous, of uniform thickness, and free of bubbles and irregularities. A clear section of each was chosen for the measurements. 

Fig. 21. Top Experimental ( H)- C cross-polarization spectrum of freshly prepared poly-e-caprolactone nanospheres in an aqueous dispersion (wc—100 MHz, full proton decoupling). Five polymer signals ( P ) are detected within the given spectral range, other resonances can be assigned to the surfactant polyvinyl alcohol and small amounts of polyvinyl acetate. Bottom Corresponding ( H)- C cross-polarization spectrum of a solid bulk sample of poly-f-caprolactone under static conditions.

If a thermal transition does cause a change in the distribution of various conformations or structures in the system, then the IR spectrum will reflect these concentration changes. Anton measured the IR absorptions sensitive to helix regularity, usually in the 900-1100 m" region, for several polymers as a function of temperature (25). Intensity decreases of these bands were observed above Tg. This change was attributed to a randomization of the chain structure. Anton illustrated this method of determining Tg for PET, polyvinyl acetate, PS, and several nylons. Other phenomena were observed at T Tg such as crystallization of PET and a crystal-crystal transformation of nylon 66. 

In the polymer industry, packing material, laminates including multilayer films, pellets or molded products can be analyzed by NIR. Even polymer latex particles with up to 99 % water content may be analyzed. NIR provides information about reaction mechanisms, polymerization, crystallinity, orientation, water content and hydrogen bonding, even during the process of polymer manufacture. For example the disappearance of the double bonds in polyethylene and polypropylene can be monitored. In the NIR spectrum C=C bonds lead to a combination band at about 4740 cm and a first overtone at about 6170 cm NIR spectroscopy is applied to characterize ester-, nitrile-, or amide-based acrylic and methacrylic polymers. Other examples are the identification of polyvinylchloride, polyvinyl alcohol and polyvinyl acetates or the analysis of polymerization in epoxy and phenolic resins. 

Uses Fungicide, algicide, biocide for exterior paints, coatings, caulks, stucco, acrylic, vinyl-acrylic, or polyvinyl acetate latexes Features Broad spectrum nonleaching noncorrosive to metals stable to radiation compat. with latex polymers contg. zinc oxide Properties Off-wh. aq. disp. si. odor sp.gr. 0.95 f.p. -5 C Use Level 5-20 lb/100 gal (exterior paint)... 

The spectrum of the first chemical component, the concentration profile ci resolved by MCR, and the 3D map of the generated matrix Xi =c x are shown in Fig. 12 the 3D map shows the decline of absorbance. The smallest peak at 1713 cm is due to the C=0 stretching vibration it is clear that PVA itself does not contain a C=0 group. Because the production of a 100 mol% degree of saponification is technically difiicult [13], usually the small C=0 residual in polyvinyl acetate (PVAc, Fig. 6b) from the saponification reaction includes the C=0 band. However, it is not clear whether the small amoimt of residual PVAc groups show absorbance values close to 0.1 or not. Since the measurement of IR spectra began at 140 °C (at which point crystalline material starts to melt), there exists a possibility that some part of the PVA formed C=0 moieties via the... 

The IR and Raman spectra of polyvinyl acetate are provided in Reference Spectrum 10. Key features of the IR spectrum of PVAc are the C=0 stretching vibration at 1740 cm , the C—O stretching vibration of the ester group at 1230 and 1020 cm , an absorption due to methyl CH bending at 1375 cm , and CH2 bending (scissors) vibration of the methylene groups at 1440 cm . An important copolymer of vinyl acetate is ethylene-vinyl acetate copolymer, EVA. For this copolymer, an increase in the number of —CH2— groups, due to the insertion of ethylene molecules into the polymer... 

Polyvinyl acetate emulsions can be further modified by the incorporation of functional groups. These groups permit the design of polymers which have the ability to bond a wider spectrum of surfaces, including difficult-to-bond substrates. The addition of functional groups also permits crosslinkability of the polymer in order to achieve a high degree of water, solvent, or heat resistance. 

However, in a recent publication, Shirinyan, Mnatsalianov, et al. (20) find that differences between the rates of vinyl acetate emulsion polymerisation observed with samples of similar polyvinyl alcohols manufactured by the same process In three different factories could be attributed to a condensation product of acetaldehyde derived from hydrolysis of residual vinyl acetate this gave rise to a conjugated ketone type ultra-violet spectrum and could be extracted from the polyvinyl alcohol under suitable conditions. This could be the uncontrolled factor which appears to have confounded nmuiy of the experiments reported here. Even more recently the same laboratory ( ) has reported that there Is an optimum sequence length of hydroxyl groups in the polyvinyl cdcohol-acetate block copolymer for polymerisation rate and dispersion stability. 

Fig. 4.59 Infrared spectrum of polyvinyl chloride (PVC) showing pristine PVC, after aging in acetic acid, and the difference between the two spectra.

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