Polyvinylacetate viscosity

Fig. 18. Viscosity (log rjinPa-s[lPa-s=10 pois]), as a function of temperature for polymethacrylate (a) PVC (b), and polyvinylacetate (c) according to Eq. (43) (WLF, theoretical curves). The diagram shows the great influence of the free volume near the glass transition temperature...

The intrinsic viscosity fell greatest in the case of the polyvinylacetate to about 45% of the initial value. An estimate of the number of scissions per molecule can serve to indicate whether this represents severe degradation or not. If we use Equation 2 to calculate the average number of scissions at the end of the experiment, as recommended by Shultz and Leahy (10), we find that the reaction had proceeded to the extent of about 4 scissions in the initial PVA molecule. 

ISH Ishihara, N., Ikeda, H., and Masuda, Y., The shear viscosity of the polyvinylacetate-3-heptanone mixture near the critical point, Nippon Reoroji Gakkaishi, 8, 39, 1980. 

Onogi, et al. used a capillary viscometer with continuously varying pressure head to determine viscosity of linear and branched polyvinylacetates in methylethylke-tone, and the viscosity of polystyrene in toluene (good solvent) and decalin (poor solvent)(50). Measurements were reported for nearly three dozen polyvinylacetates and 14 polystyrenes at a moderate number of different concentrations, and for eight polystyrenes at a larger number of concentrations. Figures 12.22-12.24 show the... 

PVA Erkol is produced by polymerisation of vinylacetate to polyvinylacetate PVAC, followed by the hydrolysis of PVAC in PVA. The degree of polymerisation determines the molecular weight and viscosity of PVA Erkol in solution. The degree of hydrolysis (saponification) signifies the extent of conversion of the PVAC to PVA. Partially hydrolysed PVA has a Tg of 58 °C and a Tm of 180 °C. Totally hydrolysed PVA has a Tg of 85 °C and a Tm of 230 °C. PVA can be used in the production of paper, clothes, glues, paints, pharmaceutical products, building materials, ceramics, etc. (Erkol, undated). 

---