Viscosity‐molecular weight relationships for low molecular weight polymers. II. Poly(vinyl acetate) and poly(methyl methacrylate)

Abstract

q]/Mn relationships a t 25°C. have been found for low molecular weight fractions of poly(viny1 acetate) (PVAc) in chlorobenzene and poly(methy1 methacrylate) (PMMA) in toluene.The PMMA used contains about 75% of syndiotactic form. Due to the difficulties of PMMA fractionation, the constants in the equation [q] = K Rg refer to an average degree of polydispersity equal to gw/an = 1.2.For both PVAc and PMMA there, is a range of molecular weight where a = 0.5; in these ranges [q] is practically indistinpishable from [ q ]~. ZUSAMMENFASSUNG: Die [q] /Bn-Beziehungen bei 25 "C fur Fraktionen niedrigeren Molekulargewichtes von Polyvinylacetat (PVAc) in Chlorbenzol und von Polymethylmetharrylat (PMMA) in Toluol wurden errnittelt. Das verwendete PMMA war zu etwa 75 yo syndiotaktisch. Wegen der Schwierigkeiten bei der Fraktionierung von PMMA beziehen sich die Konstanten in der Gleichung [q] = K @, auf einen mittleren Polydispersitatsgrad von xw/xn = 1,2. Fur beide Stoffe, sowohl PVAc a l s auch PMMA, gibt es einen Molekul.rrgewichtsbereich, in dem a = 0,5 ist; in diesem Bereich ist [q] praktisch von [ q ]~ nicht unterscheidbar. *) Part I cf..".

Modeling of Poly(methylmethacrylate) Viscous Thin Films by Spin-Coating

“…Figure 5 overlays the infrared absorbance spectra of the two samples from 4000 to 1200 cm −1 . The observed absorbance bands for methyl, carbonyl, and ester stretching modes at ~2900, ~1700, and ~1450 cm −1 have also been reported in the literature for PMMA as a bulk substance and thin film [7,17,29]. The FTIR spectra of the bulk material and the 720 nm spin-cast film are similar, consistent with the TGA results.…”

“…Nonlinear regression by Equation 7was found to converge by the sixth term ([η] = 0.292 ± 0.031, K H = 0.500 ± 0.101,). Potentially due to differences in fractional polydispersity [17] or systematic fitting errors [16], a wide range of literature values have been reported for [η] and K H combinations [18]. For this reason, experimental intrinsic viscosity determinations were compared to estimations made with the Mark-Houwink equation:…”

Transport coefficients of helical wormlike chains. 4. Intrinsic viscosity of the touched-bead model

“…Before proceeding further, we make some remarks on the numerical solutions of eq 19. As is well-known, the solutions of the Kirkwood-Riseman equations such as eq 19 possess singularities when the ratio £ of the diameter of the bead to the spacing is nearly equal to or greater than unity.12 And it leads to the negative translational diffusion coefficients12 and the negative intrinsic viscosity. 13 In the case of a rigid rod with the preaveraged Oseen tensor, these singularities never appear in the range of £ < 1, including the case of the touched-bead model.…”

Mean-square radius of gyration of oligo- and poly(methyl methacrylate)s in dilute solutions

“…In the limit XL -*-<*>, we have Then, (S2)/x and x are related to /(XL) and L as (S2)/x = (M0X-1/Ml)[/(XL; X-1^, X^l/XL] (15) and log x = log (XL) + log (X-'MJMo) (16) respectively. (Recall that Mo is the molecular weight of the repeat unit.)…”