Poly calorimetry

The thermal glass-transition temperatures of poly(vinyl acetal)s can be determined by dynamic mechanical analysis, differential scanning calorimetry, and nmr techniques (31). The thermal glass-transition temperature of poly(vinyl acetal) resins prepared from aliphatic aldehydes can be estimated from empirical relationships such as equation 1 where OH and OAc are the weight percent of vinyl alcohol and vinyl acetate units and C is the number of carbons in the chain derived from the aldehyde. The symbols with subscripts are the corresponding values for a standard (s) resin with known parameters (32). The formula accurately predicts that resin T increases as vinyl alcohol content increases, and decreases as vinyl acetate content and aldehyde carbon chain length increases. 

ADMET polymers are easily characterized using common analysis techniques, including nuclear magnetic resonance ( H and 13C NMR), infrared (IR) spectra, elemental analysis, gel permeation chromatography (GPC), vapor pressure osmometry (VPO), membrane osmometry (MO), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). The preparation of poly(l-octenylene) (10) via the metathesis of 1,9-decadiene (9) is an excellent model polymerization to study ADMET, since the monomer is readily available and the polymer is well known.21 The NMR characterization data (Fig. 8.9) for the hydrogenated versions of poly(l-octenylene) illustrate the clean and selective nature of ADMET. 

Figure 10.7 The phase diagram (a) and the glass transition temperatures (b) of a PSC/PVME mixture obtained, respectively, by light scattering and differential scanning calorimetry (DSC). Irradiation experiments were performed in the miscible region at 127 C indicated by (X) in the figure of trans-cinnamic acid-labeled polystyrene/poly(vinyl methyl ether) blends.

Thermal Analysis - Differential Scanning Calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to characterize the thermal properties of the polymers synthesized. DSC analysis was performed on a Perkin-Elmer Differential Scanning Calorimeter, Model 2C with a thermal analysis data station. Thermal gravimetric analysis (TGA) was carried out on a DuPont thermal gravimeter, Model 951. From the DSC and TGA plots of poly (N-pheny 1-3,4-dimethylene-... 

Figure 15. Differential Scanning Calorimetry (DSC) curve of 90% trans-i, 4-poly butadiene...

Block copolymers with PS and a polymethacrylate block carrying a liquid crystalline group, PS-b-poly 6-[4-(cyanophenylazo)phenoxy]hexyl methacrylate, were successfully prepared in quantitative yields and with relatively narrow molecular weight distributions (Scheme 5) [18]. The thermotropic liquid crystalline behavior of the copolymers was studied by differential scanning calorimetry. 

The synthesis of poly(anhydride-co-amide)s (Table VII) of various chemistries was pursued by Hartmann and Schulz (1989) as a means of improving biocompatibility and extending the degradation times of polyanhydrides. This work also contains calorimetry data on the thermal transitions and spectroscopic characterization. 

AFM Atomic force microscopy aPP Atactic polypropylene DSC Differential scanning calorimetry HDPE High-density polyethylene iPP Isotactic polypropylene LLDPE Linear low-density polyethylene MD Microdomain ODT Order-disorder transition PB Poly(butadiene)... 

There appear to be no reported values for the Tg of poly(TBTM) and it proved difficult to measure any meaningful transition by differential scanning calorimetry. The value of 0°C was selected as It gave a reasonable fit to experimental data when using equations 7 and 8. 

The enthalpies of interaction of tetrahydro-furan (THF) and 2,5-dimethyltetrahydrofuran (l THF) with 0.03M benzene solutions of poly-(styryl)1ithium (PSLi) and poly(isoprenyl)lithium (PILi) have been measured as a function of R ([THF]/[Li]) at 25°C using high dilution solution calorimetry. At low R values (ca. 0.2) the enthalpy of interaction of THF with PILi (-5.8 kcal/mole) is more exothermic than with PSLi (-4.5 kcal/mole). However, the decrease in enthalpy for Me,THF versus THF is larger for PILi (3.2 kcal/mole) than for PSLi (2.2 kcal/mole) at low R values. The enthalpies decrease rapidly with increasing R values for PILi, but are relatively constant for PSLi. It is suggested that THF interacts with intact dimer for PILi, but for PSLi this base coordinates to form the unassociated, THF-solvated species. 

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