Observations on HDPE Characterization with a Microcalorimeter as a Complementary Tool to TREF and CRYSTAF

Britto, L. J. D.; Soares, João B. P.; Penlidis, Alexander

doi:10.1080/10543414.2000.10744546

Cited by 3 publications

(1 citation statement)

References 7 publications

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“…The chemical composition of d-PE samples dispersed in KBr disks was investigated by FTIR. The CCD was investigated by a solution calorimetry technique 24 using TCB as the solvent at a constant cooling and heating rate between 2 and 20 °C/h. This technique fractionates according to the polymer molecular structure; homogeneous linear chains crystallize more easily than branched chains or heterogeneous chains and present higher crystallization and dissolution temperatures.…”

Section: Methodsmentioning

confidence: 99%

Chain-Exchange Dynamics at a Polymer−Solid Interface: Effects of Polydispersity and Shear Stress on Linear Low-Density Polyethylene Flow

Esperidião

2003

Ind. Eng. Chem. Res.

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Polymer-surface interactions in flowing systems were studied using an attenuated total reflectance Fourier transform infrared spectroscopy technique. The absorbance of deuterated polyethylene, d-PE66 (M w ) 6.60 × 10 4 ) and d-PE112 (M w ) 1.12 × 10 5 ), near the surface of a flat zinc selenide crystal was followed as it was replaced by linear low-density polyethylene (M w ) 1.07 × 10 5 ). The experiments were performed under wall stresses of 0.090, 0.134, and 0.155 MPa using a rectangular flow channel formed by a ZnSe crystal and an aluminum block. The decay profiles depended on the molecular weight distribution, the chemical composition distribution, and the shear stress. For d-PE112, the decay profiles suggest that slip is due to a cohesive failure. For d-PE66, the slip mechanism appeared to be due to adhesive failure. For d-PE112 with larger and regular chains, an immobile layer forms whose thickness (12-17 nm) depended on the wall shear stress.

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Section: Methodsmentioning

confidence: 99%

Chain-Exchange Dynamics at a Polymer−Solid Interface: Effects of Polydispersity and Shear Stress on Linear Low-Density Polyethylene Flow

Esperidião

2003

Ind. Eng. Chem. Res.

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Correlation of the elution behavior in temperature rising elution fractionation and melting in the solid‐state and in the presence of a diluent of polyethylene copolymers

Mirabella¹

2001

J Polym Sci B Polym Phys

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Compositionally homogeneous poly(ethylene-␣-olefin) random copolymers with 1-butene and 1-hexene comonomers have been studied. The melting of solutioncrystallized specimens of these copolymers in the presence of trichlorobenzene as a diluent with differential scanning calorimetry (DSC) is well correlated with analytical temperature rising elution fractionation (A-TREF) elution temperature profiles. This indicates that the A-TREF experiment is essentially a diluent melting experiment. Furthermore, the correction of the corresponding solid-state melting endotherms of these copolymers with Flory's diluent melting equation yields curves that also correlate very well with the DSC diluent melting curves and the A-TREF elution temperature profiles. Values of , the Flory-Huggins interaction parameter, are determined for these copolymers in trichlorobenzene. decreases as short-chain branching increases. The A-TREF elution temperature profiles of one of these copolymers are the same, within experimental error, for dilute-solution crystallizations of the copolymer performed over an extremely broad time schedule (10 s to 3 days). This indicates the profound effect of the branches, as limiting points of the ethylene sequences, in controlling the crystal thickness distribution, which in turn controls the melting point in the presence of the diluent, or the elution temperature from the A-TREF.

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Fractionation and Characterization for a Propylene–Ethylene Random Copolymer

Zhang

Zhu

2002

Polym J

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ABSTRACT:A random copolymer of propylene with 3.5 mol% ethylene comonomer is firstly fractionated by temperature rising elution fractionation (TREF). Techniques including 13 C nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), gel-permeation chromatography (GPC), crystallization analysis fractionation (Crystaf) and differential scanning calorimetry (DSC) are used to characterize the obtained fraction polymers. The results show that each fraction polymer is composed mainly of isotactic propylene sequence plus a small amount of ethylene comonomer and has uniform molecular weight and ethylene content. The PPP, PPE, and PEP are main part of triad sequence unit. As the elution temperature increasing, ethylene content of the fraction polymers decreases, number average molecular weight increases, and meanwhile number average sequence length of propylene, n P , increases, while that of ethylene, n E , decreases, close to 1. The results show that ethylene content affects linearly the melting temperature (T m ) in a range of ethylene content being as low as less than 10.23 mol%; there is a linear relationship between the reciprocal melting temperature (1000/T m , K −1 ) and reciprocal number average molecular weight (M Polypropylene is a common semi-crystalline synthetic polymer, and its macromolecular chain structure is an important factor to affect such properties of propylene polymers as crystallization behavior, morphologies, melting temperature, degree of crystallization, toughness, and rheological and optical properties. By the way of introducing some comonomers (e.g., ethylene) into its macromolecular chain, the performance of propylene polymers can be improved purposefully and effectively. Because propylene tacticity and ethylene comonomer complicate the macromolecular chain structure, and can farther lead to complex crystallization behaviors and morphologies, it is very important to firstly characterize the macromolecular chain structure well. In order to investigate thoroughly the relationship between performance and macromolecular chain structure, it is necessary to make samples uniform. Temperature rising elution fractionation (TREF) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] has been shown to be a powerful technique to make crystal polyolefins uniform on the basis of their crystallizability and molecular weight. Through TREF experiments, a set of fraction polymers with uniform molecular weight and content of ethylene comonomer can be obtained; hereafter crystallization analysis fractionation (Crystaf) will be used to check the effect of fractionation by analyzing such parameters as σ and R, 16 which can define the broadness of the crystallization temperature distribution of the fraction polymers. [16][17][18][19][20][21][22] Up to now most samples of propylene copolymers on investigation are the impact propylene-ethylene copolymers, a very complex blend. Even though after they have been fractionated by TREF, 3-11 each fraction polymer also consists of PE, ...

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Observations on HDPE Characterization with a Microcalorimeter as a Complementary Tool to TREF and CRYSTAF

Cited by 3 publications

References 7 publications

Chain-Exchange Dynamics at a Polymer−Solid Interface: Effects of Polydispersity and Shear Stress on Linear Low-Density Polyethylene Flow

Chain-Exchange Dynamics at a Polymer−Solid Interface: Effects of Polydispersity and Shear Stress on Linear Low-Density Polyethylene Flow

Correlation of the elution behavior in temperature rising elution fractionation and melting in the solid‐state and in the presence of a diluent of polyethylene copolymers

Fractionation and Characterization for a Propylene–Ethylene Random Copolymer

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