Polystyrene intrinsic viscosity

Measured by gel permeation chromatography based on standard polystyrene. Intrinsic viscosity. 

Fox and Floryf used experimental molecular weights, intrinsic viscosities, and rms end-to-end distances from light scattering to evaluate the constant in Eq. (9.55). For polystyrene in the solvents and at the temperatures noted, the following results were assembled ... 

The intrinsic viscosity of polystyrene in benzene at 25°C was measuredf for polymers with the following molecular weights ... 

MFI = melt flow index IV = intrinsic viscosity in CH2CI2 at 25°C From gel-permeation chromatography using polystyrene standards. 

In HOPC, a concentrated solution of polymer is injected. The concentration needs to be sufficiently higher than the overlap concentration c at which congestion of polymer chains occurs. The c is approximately equal to the reciprocal of the intrinsic viscosity of the polymer. In terms of mass concentration, c is quite low. For monodisperse polystyrene, c is given as (4)... 

The most widely used molecular weight characterization method has been GPC, which separates compounds based on hydrodynamic volume. State-of-the-art GPC instruments are equipped with a concentration detector (e.g., differential refractometer, UV, and/or IR) in combination with viscosity or light scattering. A viscosity detector provides in-line solution viscosity data at each elution volume, which in combination with a concentration measurement can be converted to specific viscosity. Since the polymer concentration at each elution volume is quite dilute, the specific viscosity is considered a reasonable approximation for the dilute solution s intrinsic viscosity. The plot of log[r]]M versus elution volume (where [) ] is the intrinsic viscosity) provides a universal calibration curve from which absolute molecular weights of a variety of polymers can be obtained. Unfortunately, many reported analyses for phenolic oligomers and resins are simply based on polystyrene standards and only provide relative molecular weights instead of absolute numbers. 

The results of intrinsic viscosity measurements for four polymer-solvent systems made at the -temperature of each are shown in Fig. 141. The four systems and their -temperatures are polyisobutylene in benzene at 24°C, polystyrene in cyclohexane at 34°C, poly-(di-methylsiloxane) in methyl ethyl ketone at 20°C, and cellulose tricapry-late in 7-phenylpropyl alcohol at 48°C. In each case a series of poly-... 

Figure 2. Intrinsic viscosity-molecular weight data for polystyrene and polyvinyl chloride measured by osmometry and by SEC using broad MWD standard calibration (polystyrene (m) M = 7,06 X 10 in THF/1% PPG (O) [ ] =...

Materials. Four samples of sodium poly(styrenesulfonate) (NaPSS) prepared by sulfonation of polystyrenes with narrow molecular weight distribution were purchased from Pressure Chemical Co. The characteristics of the samples, according to the manufacturer, are listed in Table I. The intrinsic viscosities of NaPSS in aqueous NaCl solution were measured using an Ubbelhode viscometer at 25 °C. 

Figure 3.4 Intrinsic viscosity-molecularweight relation in toluene at 35°Cfor O regular H-polystyrene 12-arm star polystyrene A comb polystyrene with f= 30, Afbb = 2.75x 105 and increasing branch MW. Top line linear polystyrene...

Tab. 5.7 Intrinsic viscosity vs irradiation time of polystyrene in benzene (1 %).

Figure 10 shows DRI and viscometer traces for the NBS 706 polystyrene standard. Based on the information from these two chromatograms in conjunction with the universal calibration curve, one can calculate the intrinsic viscosity EnJCv) and molecular weight M(v) at each retention volume as shown in... 

The use of a continuous GPC viscosity detector in conjunction with a DRI detector permits the quantitative determination of absolute molecular weight distribution in polymers. Furthermore, from this combination one can obtain Mark-Houwink parameters and the bulk intrinsic viscosity of a given polymer with a GPC calibration curve based only on polystyrene standards. Coupling these two detectors with ultraviolet and infrared detectors then will permit the concurrent determination of polymer composition as a function of molecular weight and... 

Due to the high sensitivity of the viscometer, accurate readings of viscosity responses can be made with sample h gi values much less than 1.1. Therefore, saitple solutions of very low concentration can be analyzed in the viscometer to produce a single point intrinsic viscosity determination without the need of concentration extrapolation. As shown in Figure 7 for a polystyrene saitple, any h- u determination at the value of... 

Figure 3 Intrinsic-viscosity plots for the polystyrene standards a) PS Narrow 114K,...

Studies of polystyrene standards in THF solvent are not uncommon. however, bothersome discrepancies still exist in the literature and in practice. For example, the published Mar 1<-Houw i nk parameters are in wide disagreement il. The purpose of this work is to examine a large number of PS standards from multiple suppliers, covering a wide range of molecular weights. T -,e intrinsic viscosities and GPC retention volumes have been measured and used independently to correlate and crosscheck the molecular weights provided by the suppliers. 

Dead Volume. The dead volume difference between the viscometer and DRI must be accounted for. Otherwise systematic errors in Mark-Houwink parameters K and u can occur. In the previous paper (16), a method developed by Lesec and co-workers (38) based on injecting a known amount of a very high molecular weight polystyrene standard onto low porosity columns was used. From the viscometer and DRI chromatograms, the apparent intrinsic viscosity [h] was plotted against retention volume V. A series of [n] vs. V plots are then constructed assuming a range of dead volume, AV. 

The polymer samples studied here fall into three distinct categories. Data from two sample populations have been combined in the SAN copolymer study. A group of SAN materials having compositions ranging from 42 (wt)% AN to 82% AN were polymerized and characterized quite some time ago (1972), with intrinsic viscosities determined only in DMF. Very recently, a second group of SAN s with compositions from 5 (wt)% to 48% AN, as well as one sample of polystyrene (0% AN), were polymerized and characterized, with intrinsic viscosities determined in DMF, THF, and MEK. These two populations are differentiated in the Results section by the designations "old data" and "new data". The third category of samples is that of S/MA copolymers and S/MA/MM terpolymers, with intrinsic viscosities measured only in MEK. 

The less extensive intrinsic viscosity data for SAN in THF and in MEK (all "new" data) are given in Table I and are plotted in Figure 3, again following from eq.(6), this time including the polystyrene and low AN samples. 

Initial intrinsic viscosity, dl/g Free polyfmethyl acrylate) Free polystyrene Block copolymer... 

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