Study of crystallization of industrial polyethylene and polyethylene mixtures

Fikhtner, R.R.; Volkov, T.I.; Shalatskaya, S. A.; Trizno, M. S.

doi:10.1016/0032-3950(79)90237-5

Cited by 4 publications

(2 citation statements)

References 4 publications

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“…where 01 is a length characterizing the spatial dimensions via an exponential correlation function.37•38 \ and 2 are the volume fractions and and 2 are the scattering length densities of the two phases.1 The sizes of the domains may be estimated from the mean chord intercept lengths39 II a (6) L 2 -<Zi/</>2 (7) Small-angle X-ray scattering intensities were collected on the ORNL 10 m SAXS camera, with pinhole collimation40 and hence minimal instrumental smearing effects.41…”

Section: Small-angle Neutron Scattering: Data Collectionmentioning

confidence: 99%

Morphology of Blends of Linear and Long-Chain-Branched Polyethylenes in the Solid State: A Study by SANS, SAXS, and DSC

Wígnall¹,

Londono²,

Lin³

et al. 1995

Macromolecules

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Differential scanning calorimetry (DSC), small-angle neutron scattering (SANS), and X-ray scattering (SAXS) have been used to investigate the solid-state morphology of blends of linear (high density) and long-chain-branched (low-density) polyethylenes (HDPE/LDPE). The blends are homogeneous in the melt, as previously demonstrated by SANS using the contrast obtained by deuterating the linear polymer. However, due to the structural and melting point differences (~20 °C) between HDPE and LDPE, the components may phase segregate on slow cooling (0.75 °C/min). For high concentrations (

0.5) of HDPE, relatively high rates of crystallization of the linear component lead to the formation of separate stacks of HDPE and LDPE lamellae, as indicated by two-peak SAXS curves. For predominantly branched blends, the difference in crystallization rate of the components becomes smaller and only one SAXS peak is observed, indicating that the two species are in the same lamellar stack. Moreover, the phases no longer consist of the pure components and the HDPE lamellae contain up to 15-20% LDPE (and vice versa). Rapid quenching into dry ice/2-propanol (-78 °C) produces only one SAXS peak (and hence one lamellar stack) over the whole concentration range. The blends show extensive cocrystallization, along with a tendency for the branched material to be preferentially located in the amorphous interlamellar regions. For high concentrations ( > 0.5) of HDPE-D, the overall scattering length density (SLD) is high and the excess concentration of LDPE between the lamellae enhances the SLD contrast between the crystalline and amorphous phases. Thus, the interlamellar spacing (long period) is clearly visible in the SANS pattern. The blend morphology is a strong function of the quenching rate, and samples quenched less rapidly (e.g., into water at 23 °C) are similar to slowly cor'ed blends. The combination of SANS, SAXS, and DSC techniques allows us to interpret morphological differences in the solid state of these blends.

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Section: Small-angle Neutron Scattering: Data Collectionmentioning

confidence: 99%

Morphology of Blends of Linear and Long-Chain-Branched Polyethylenes in the Solid State: A Study by SANS, SAXS, and DSC

Wígnall¹,

Londono²,

Lin³

et al. 1995

Macromolecules

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“…The study of the structure of low-density and high-density polyethylene blends using an optical method, depending on their behavior during crystallization, showed [8] that the formation of spherulites and the increase in their size before a collision occurs during the crystallization of high-density polyethylene, forming the initial moment of the spherulites skeleton. Table 2 shows the results of studying the effect of the concentration of bentonite on the temperature of the onset of crystallization of the density of the considered nanocomposite materials at room temperature and at 190 0 C. As can be seen, 1 mass % content of bentonite in a mixture of LDPE/HDPE does not have any change on the temperature of the beginning of the crystallization process, and is equal to 115 0 C. Density at room temperature is also remains unchanged, but for density at a temperature of 190 0 C there is a slight decrease.…”

Section: Resultsmentioning

confidence: 99%

Effect of Bentonite Concentration on Properties and Regularity of Crystallization of Nanocomposite Materials Basis on the of Mixtures of High and Low Density Polyethylene

Mustafayeva¹,

Kakhramanov²,

Arzumanova³

et al. 2020

AChJ

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Miscibility of linear and branched polyethylene in the liquid state

Illers¹,

Köhnlein²

1986

Makromol. Chem.

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HDPE/LDPE blends and the pure components were crosslinked either by irradiation or by di-tert-butyl peroxide in the liquid state. The degree of crosslinkage was characterized by the reciprocal degree of swelling Q -1 (xylene, 2 h, 140°C). Above a critical degree of crosslinkage corresponding to Q -l = 0,2 the DSC curves of HDPE/LDPE blends show only one single crystallization peak on cooling from the melt and only one single melting peak on subsequent heating. This is an unequivocal proof for the single phase structure of HDPE/LDPE blends in the liquid state. Crosslinking with Q-I 2 0,2 prohibits fractional crystallization and forces the unbranched CH, sequences of both components between the crosslinks into one crystal lattice.

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Study of crystallization of industrial polyethylene and polyethylene mixtures

Cited by 4 publications

References 4 publications

Morphology of Blends of Linear and Long-Chain-Branched Polyethylenes in the Solid State: A Study by SANS, SAXS, and DSC

Morphology of Blends of Linear and Long-Chain-Branched Polyethylenes in the Solid State: A Study by SANS, SAXS, and DSC

Effect of Bentonite Concentration on Properties and Regularity of Crystallization of Nanocomposite Materials Basis on the of Mixtures of High and Low Density Polyethylene

Miscibility of linear and branched polyethylene in the liquid state

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