Isothermal and non-isothermal crystallization of PP: effect of annealing and of the addition of HDPE

Blom, H. P.; Teh, Jiashen; Bremner, Tim; Rudin, Alfred

doi:10.1016/s0032-3861(97)10305-6

Cited by 61 publications

(40 citation statements)

References 19 publications

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“…5 However, Blom et al 6 recently reported that HDPE was able to penetrate the PP phase sufficiently at low HDPE concentrations to reduce the number and size of high segment density regions, thereby delaying the nucleation and subsequent crystallization of the PP phase. They concluded that there was a certain degree of interaction between PP and HDPE at HDPE concentrations below 20%.…”

Section: Introductionmentioning

confidence: 99%

Isothermal crystallization and spherulite structure of partially miscible polypropylene–linear low‐density polyethylene blends

Shanks

2001

J of Applied Polymer Sci

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ABSTRACT:Polypropylene (PP) was blended with a linear low-density polyethylene (LLDPE, containing 5% hexene comonomer) over a composition range of 10 -90% of PP. The crystallization and morphology of the PP-LLDPE blends were studied by differential scanning calorimetry (DSC), polarized optical microscopy with a hot stage (HSOM), and scanning electron microscopy (SEM). In particular, the isothermal crystallization of PP in molten LLDPE was investigated. It was observed that the crystallization and melting behavior of PP and LLDPE changed in the blends, indicating that there was some degree of miscibility between the PP and the LLDPE. A depression of the equilibrium melting temperature (T m 0 ) of PP in the blends with no more than 15% of PP confirmed that PP was miscible with LLDPE at and below 15% of PP. In addition, a drastic decrease in T m 0 from the 25% PP blend to the 20% blend led us to conclude that the miscible behavior between PP and LLDPE became favorable at a PP concentration of 20%. The optical microscopic images showed that, in the blends with 10 and 15% of PP, the PP crystallized as open-armed diffuse spherulites, similar to those in the miscible blends. In contrast, the PP crystallized in a phase-separated matrix or droplets with more than 25% of PP, when obvious phase separation occurred. The SEM image revealed that the PP lamella was able to penetrate the PP and LLDPE phase boundary and grow in the LLDPE phase. The above results displayed that the PP dissolved in the LLDPE, and, particularly, when the PP concentration was below 20%, the dissolution was substantial.

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Section: Introductionmentioning

confidence: 99%

Isothermal crystallization and spherulite structure of partially miscible polypropylene–linear low‐density polyethylene blends

Shanks

2001

J of Applied Polymer Sci

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“…[20] Other reports show that after melting of high molecular-weight polymers, a long-lived heterogeneous non-equilibrium melt structure can remain, [21,22] where the presence of ordered regions facilitates a subsequent crystallization. [23,24] It should be mentioned that it is an open question whether it is nucleation or actual growth that is most affected in the mentioned cases.…”

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confidence: 99%

Crystallization Kinetics of Poly(dimethylsiloxane) Molecular‐Weight Blends—Correlation with Local Chain Order in the Melt?

Maus

Saalwächter

2007

Macro Chemistry & Physics

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The crystallization of bimodal PDMS molecular‐weight blends consisting of long (115 kda) and short (5.3 kda) chains is investigated using DSC and proton NMR. In agreement with earlier studies, it is found that the pure long‐chain sample crystallizes more rapidly than the short‐chain sample. Furthermore, the rate passes through a maximum for the 60:40 blend. These observations hold true for non‐isothermal cooling at −5 K · min−1 and isothermal crystallization at 203 K (both DSC) as well as at 218 K (NMR). The samples with 40% long chains or less crystallize to about 75–80% under all conditions, and the crystalline fractions derived from DSC and NMR agree very well, thus also confirming the literature value of 61.3 J · g−1 as the perfect heat of fusion for PDMS, and disproving some earlier studies. A relation of the crystallization kinetics with entanglement‐induced segmental orientation correlations in the melt is postulated. The local chain order is characterized by proton multiple‐quantum NMR, and an attempt is made to correlate this observable with a reduced crystallization rate, corrected for effects of chain transport.magnified image

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“…5 and 6. As in mechanical degradation [5,10,11], when a tension is applied in electrical degradation, the punching is not immediate but has a kinetic character. A certain time is needed for punching and the electric field applied during this time develops a chain of events preparing the punching in the sample.…”

Section: Dw-f(e)mentioning

confidence: 99%

Temperature and time dependence of electrical and mechanical durability of LDPE/diamond composites

Boydaǧ¹,

Özcanli²,

Alekberov³

et al. 2005

Composites Part B: Engineering

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Isothermal and non-isothermal crystallization of PP: effect of annealing and of the addition of HDPE

Cited by 61 publications

References 19 publications

Isothermal crystallization and spherulite structure of partially miscible polypropylene–linear low‐density polyethylene blends

Isothermal crystallization and spherulite structure of partially miscible polypropylene–linear low‐density polyethylene blends

Crystallization Kinetics of Poly(dimethylsiloxane) Molecular‐Weight Blends—Correlation with Local Chain Order in the Melt?

Temperature and time dependence of electrical and mechanical durability of LDPE/diamond composites

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