Crystallisation of blends of LLDPE with branched VLDPE

Shanks, Robert A.; Amarasinghe, Gandara

doi:10.1016/s0032-3861(99)00678-3

Cited by 34 publications

(19 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…One can calculate that an approximate 70% time saving gain is obtained per selfnucleation and annealing cycle (where one cycle comprises heating from À20 8C to 120 8C at a specific scanning rate, a holding time of 5 min at 120 8C, and then cooling from 120 8C to À20 8C) if 50 8C Á min À1 is used instead of 10 8C Á min À1 . In any case, 78 min is the fastest thermal fractionation time ever reported in the literature [4] (compared with commonly used values like 12 or 24 h [4][5][6][7] ) and with resolution equivalent to usual conditions involving 10 8C Á min À1 (see Figure 2 and Table 2). Table 2 reports typical thermal fractionation times employing SSA and step crystallization (SC).…”

Section: Ssa Fractionation Performed Under Conventional Versus High Smentioning

confidence: 79%

“…[4] The experiment is performed by differential scanning calorimetry (DSC). The techniques of step crystallization (SC), where a programmed step cooling is applied, [4][5][6][7] and successive self-nucleation and annealing (SSA), where a series of heating and cooling cycles are employed, [4,[8][9][10][11][12] are the two most frequently used thermal fractionation techniques and their advantages and shortcomings have been recently reviewed. [4] In thermal fractionation methods, the polymer chains are never physically separated and therefore the technique is sensitive to linear and uninterrupted chain sequences, i.e., MSL.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High Speed SSA Thermal Fractionation and Limitations to the Determination of Lamellar Sizes and Their Distributions

Lorenzo

Arnal

Müller

et al. 2005

Macro Chemistry & Physics

View full text Add to dashboard Cite

Summary: The technique of successive self‐nucleation and annealing (SSA) has been applied using differential scanning calorimetry (DSC) to a model hydrogenated polybutadiene prepared by anionic polymerization and to a commercial Ziegler‐Natta ethylene/1‐butene copolymer. Here, it is shown that the use of high scanning rates (50 °C · min−1) in the SSA protocol can reduce the thermal fractionation time to only 78 min in length (if 6 fractions are produced with a fractionation window of 5 °C), taking into consideration the need to compensate the increment in heating rates by reducing the sample mass. This time is much shorter than those previously achieved by thermal fractionation in the literature, where fractionation times of 12 or 24 h are common. Potentially, much higher rates could be employed by further reducing the fractionation times by SSA. For the first time, a distribution of lamellar thicknesses has been obtained by transmission electron microscopy after SSA fractionation and compared to distributions calculated by the Thomson‐Gibbs equation. It is shown that the results are highly dependent on the equilibrium melting temperatures employed in the calculations, and it is recommended that the values of lamellar thicknesses obtained are checked by comparing with methylene sequence lengths derived from calibration measurements available in the literature. The Thomson‐Gibbs equation is useful for comparing lamellar thickness distributions obtained by SSA with different polymers only on a semi‐quantitative basis.

show abstract

Section: Ssa Fractionation Performed Under Conventional Versus High Smentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

High Speed SSA Thermal Fractionation and Limitations to the Determination of Lamellar Sizes and Their Distributions

Lorenzo

Arnal

Müller

et al. 2005

Macro Chemistry & Physics

View full text Add to dashboard Cite

show abstract

“…[14][15][16][17][18][19][20][21][22] Mu †ller and Arnal 23 summarized these results and they observed that, in thermal fractionation, the polymer chains are never physically separated, and therefore the technique is sensitive to linear and uninterrupted chain sequences. This implies that thermal fractionation is equally sensitive to both intra-and intermolecular defects.…”

Section: Introductionmentioning

confidence: 99%

Thermal fractionation and properties of different polyethylene/wax blends

Hato

Luyt

2007

J of Applied Polymer Sci

View full text Add to dashboard Cite

The influence of paraffin-wax type and content on the properties of its blends with HDPE, LDPE, and LLDPE was investigated. Melt-mixing of HDPE with wax gave rise to completely miscible blends for both 10 and 20% wax contents. A wax content of 30% gave rise to a partially miscible blend. These observations were supported by the thermal fractionation (stepwise cooling) results. Melt-mixing of LDPE with hard paraffin wax gave rise to a partially miscible blend for all wax contents investigated, while complete miscibility was observed for the 10% oxidized hard paraffin wax containing blend. Complete miscibility was observed for all the LLDPE/A1 wax blends, with A1 wax as an oxidized hard paraffin wax. This indicates possible cocrystalli-zation of this wax with LLDPE, which was also evident from the thermal fractionation curves. LLDPE blends with hard paraffin wax were, however, partially miscible for all wax contents. All the observations were supported by the surface free energy results. It is further clear from the thermal fractionation results that the presence of wax changed the crystallization behavior of LDPE and LLDPE. Changes in the tensile properties are explained in terms of the miscibility and proposed morphologies of the blends.

show abstract

“…Linear low density polyethylene (LLDPE) film is used in many film applications where flexibility, toughness and strength are required (Shanks & Amarasinghe, 2000) and is widely used for food contact layer of packaged foodstuffs. However there is little information on the effect of g-irradiation on residues and migration levels of antioxidants and their decomposition products in LLDPE packaging film.…”

Section: Introductionmentioning

confidence: 99%