Evaluation of the heterogeneity in linear low-density polyethylene comonomer unit distribution by differential scanning calorimetry characterization of thermally treated samples

Characterization of comonomer distributions in ethylene/diene copolymers by13C-NMR, and using the segregation fractionation technique by DSC and DMTA

“…The melting curve is a reflection of the lamellar thickness distribution and a qualitative characterization of the comonomer distribution in the copolymers can be obtained. 21,26,29 The DMA measurements were done on rectangular sample plaques compression molded at 200°C using a Fontune table press TP 400 and a special mold to give the right dimensions. The mean dimensions of the sample plaques between the clamps were 2 ϫ 4 ϫ 15 mm and the threepoint bending mode was used in the measurements.…”

“…Several papers on characterizing molecular heterogeneity parameters used recently have been reported. 20 -29 Different procedures have been applied including stepwise isothermal segregation technique (SIST), 20 thermal fractionation, 21,27 segregation fractionation technique (SFT), 26,28 step crystallization (SC), 29 and successive self-nucleation/annealing (SSA). 29 In a recent study, 26 we found that the use of SFT with DSC, with successive annealing of the polymer at different temperatures starting just above the melt temperature of the polymer, provided valuable information about the chemical composition distribution (CCD) in commercial Ziegler-Natta (Z-N) and metallocene-type commercial LLDPEs and very low density PEs (VLDPE).…”

Thermal and mechanical analysis of metallocene‐catalyzed ethene–α‐olefin copolymers: The influence of the length and number of the crystallizing side chains

“…The numerous applications that have been recently developed are also reviewed. 5 Segregation studies by stepwise annealing with differential scanning calorimetry (DSC) have been applied to different types of Z-N- [6][7][8][9][10] and metallocene-catalyzed ethene copolymers. [8][9][10][11][12] The results show that differences in the ethylene sequence distributions can be seen when the polymers are annealed in steps at successively lower temperatures.…”

“…Polymer samples were measured at 75 MHz at 100 8C from 300 mg of polymer in 2.5 mL of 1,2,4-trichlorobenzene and 0.5 mL of benzene-d 6 . Three thousand scans were taken with the Waltz-16 decoupling method.…”

Strong influences of polymerization temperature on ethylene/1-hexene copolymerization catalyzed by (2-PhInd)2ZrCl2/methyl aluminoxane

“…To characterize the chain structure of the copolymers, crystallization segregation thermal analysis (Adsson et al, 1992;Starck, 1996) of samples was adopted, and the melting scan DSC curves are show in Fig.4 and Fig.5.…”