Column polymers

Figure 5 shows the separation of the plasticiser components present in a PVC-based cling film. The sample was first dissolved in tetrahydrofuran and then the components present separated by size exclusion chromatography (SEC) using mixed bed-E columns (Polymer Laboratories) and tetrahydrofuran eluting solvent. IR spectra of the separated components were then obtained using "LC-Transform " (Lab Connections) equipment. Components as they elute from... 

Polymer Laboratories Rapid Screening column, Polymer Laboratories Ltd., Shropshire, U.K. Available at http //www.polymerlabs.com/... 

PSS Highspeed columns, Polymer Standards Service GmbH, 55120 Mainz, Germany. Available at http / / www.polymer.de/... 

The chromatograph (Waters Associates) was fitted with PL Gel columns (Polymer Laboratories Ltd.) and two Infrared detectors in series. Chloroform was used as the eluant. Infrared detectors were used because the tin containing acrylic mommier has a characteristic carbonyl stretching frequency at 1620 cm which is well removed from that of other acrylic monomers which have, carbonyl absorptions at the more characteristic wavenumber 1720 cm . Both peaks obeyed the Beer Lambert law. A typical chromatogram showing the separation of residual monomers and polymer Is shown in Figure 1. 

SEC measurements with 500 S, lOA X and 10 K Ultrastyragel columns polymer concentrations were 3.5-5.5 mg/mL In samples Injected Into TCB at 0.5 mL/min flow rate. 

Molecular weight and polydispersity of the acetone extracted fractions from thermally degraded samples were determined by SEC with a Jasco PU-1580 HPLC pump equipped with two Pigel mixed D columns (Polymer Laboratories UK) connected in series, and a Jasco 830RI refractive index detector. Sample elution was with THF at 1 ml/minute flow rate. The instrument was calibrated with standard polystyrene samples. 

Three 7.5 mm i.d. X 300 mm PLgel 5 )iim Mixed-C columns (Polymer Laboratories, Amherst, MA) were thermostated to 30.0°C. Uninhibited tet-rahydrofuran (THF) at a nominal flowrate of 1.0 mL/min was used as the eluent. Narrow distribution polystyrene standards (Polymer Laboratories) were injected in a volume of 100 ijlL with concentrations ranging from 0.1 to 2.5 mg/mL, depending on molecular weight. Broad molecular-weight-distribution polystyrene 18,242-7 was obtained from Aldrich Chemical Company (Milwaukee, WI). Acetone, added to each sample at a concentration of 0.1%, was used as a flow marker. 

Hi) Molecular Weight. A Waters Associates gel permeation chromatograph fitted with a model 6000A pump, U6K injector and UV, IR and RI detectors was used for the estimation of molecular weights, molecular weight distribution and copolymer composition. Both analytical and preparative gel columns (Polymer Laboratories Ltd) were employed. Analyses were carried out at 25 t in THF and the column sets were calibrated with monodisperse polystyrene standards (Polymer Laboratories Ltd). 

Stratospheres SPE Resins, mini high load scavenger resin columns , Polymer Laboratories (now a part of Varian Inc.). 

Proportions and exact conditions required for optimum conversions and yields of diester are proprietary. Recovery of the dimethyl terephthalate product from unreacted starting materials, etc., is by distillation using a series of four or five columns. Polymer-grade material (m.p. 142°C b.p. 288°C) is obtained by distillation under reduced pressure from the top of the last fractionating column. 

Fig. 10. SEC chromatograms of ring PSs solid line) and corresponding linear precursors (dashed line). Linear polymers elute earlier than rings but the elution peaks are partially overlapped. Some elution peaks of ring polymers show small shoulders at lower retention time indicating the contamination of the linear precursors. Two SEC columns (Polymer Lab. mixed C) were used with THE eluent at a flow rate of 1.0 ml/min. Reproduced from [105] with permission...

Fig. 35. SEC calibration curves of different stereoregular PEMA samples Ued circles syndio-tactic-PEMA,/i/ted squares moderately syndiot ctic-PEMA, filled triangles isotactic-PEMA) whose rr triad content are 0,53, and 91 %, respectively. Dashed line is a calibration curve obtained from three PS standards open squares), 30.9,11.6, and 3.3 kg/mol. Column two mixed bed columns (Polymer Lab., Mixed C), Eluent THE at a flow rate of 0.8 ml/min, column temperature 40°C. Reproduced from [190] with permission...

The dendron product was analyzed by gel permeation chromatography (GPC) at 1% in DMF (Polymer Laboratories PL-EMD 950 evaporative mass detector Polymer Laboratories 5 fim Mixed D 300 x 7.5 and 5 fim 500 A 300 x 7.5 in series columns Polymer Laboratories, Amherst, MA). The chromatograms from the mass detector, which allowed a measurement of the mass of polymer, were compared with the UV adsorption at 300 nm (Fmoc absorption esoo = 6558 L cm mol ) in order to calculate the percentage of coupling. 

In the case of some complex plastic systems (e.g., blends), the development of interfaces such as the Lab Connections LC Transform, have proved very useful in increasing the amount of information that can be obtained in a GPC analysis by enabling IR data to be recorded on the resultant chromatogram. Hence, with the correct choice of separating column, polymer blends can be separated and identified as well as plasticisers. 

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