Nonisothermal crystallization kinetics of linear bimodal–polyethylene (LBPE) and LBPE/low‐density polyethylene blends

Gao, Jungang; Yu, M.; Li, Yanfang; Li, Zhiting

doi:10.1002/app.12464

Cited by 4 publications

(7 citation statements)

References 8 publications

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“…Another reason is that at a given temperature the crystallization processes with different cooling rates are at different stages, i.e., lower cooling rate processes are toward the end of the crystallization process, whereas at the higher cooling rate, the crystallization process is at an early stage. Although Ozawa's approach can be used to describe the non-isothermal crystallization behavior of low density polyethylene (LDPE), [23] the variation in the slope with temperature means that the parameter n is not a constant during crystallization and that Ozawa's approach is not a good method to describe the non-isothermal crystallization process of HDPE/EOC blends. As reported by Eder and Wlochowicz [24] the Ozawa equation is not valid for linear PE because of a high degree of secondary crystallization.…”

Section: Non-isothermal Crystallization Kineticsmentioning

confidence: 99%

Study on the Phase Behavior of High Density Polyethylene – Ethylene Octene Copolymer Blends

Mileva

Radusch

Betchev

2007

Macro Materials & Eng

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The processes of melting and crystallization of blends based on HDPE and EOC were investigated. DSC thermograms showed that a separate crystallization and co‐crystallization occurred in the blends studied. Avrami approach was used to analyze the kinetics of crystallization in the blends. It is shown that the Avrami exponent depends on the EOC concentration of the samples studied. The difference in the Avrami parameters for HDPE, EOC and the blends indicated that the nucleation mechanism and dimension of the spherulite growth of the blends were different from that of HDPE to some extent. The crystal growth was examined in the context of the Lauritzen‐Hoffman theory. DSC traces obtained at different cooling rates were used for analyzing the non‐isothermal crystallization. It was found that the Ozawa model was rather inapplicable for the materials studied. In contrast, the Avrami equation modified by Jeziorny can be used more efficiently to describe the non‐isothermal crystallization behavior of HDPE‐EOC blends.magnified image

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Section: Non-isothermal Crystallization Kineticsmentioning

confidence: 99%

Study on the Phase Behavior of High Density Polyethylene – Ethylene Octene Copolymer Blends

Mileva

Radusch

Betchev

2007

Macro Materials & Eng

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“…For bead processes, including foaming, blending is a practical way to manipulate the microstructural behavior of the materials to suit specifications. But, as observed in DSC thermograms [7][8][9][10][11][12][13][14][15][16][17][18][19][20], a blend's thermal behavior can differ significantly compared with that of its constituent components, although material types and weight ratios remain influential. For example, it has been found that adding an amount of less than 25% by weight ratio of low-molecular-weight linear polyethylene to linear-low-density polyethylene (LLDPE) promotes dual peaks generated in a DSC curve [9,10], whereas a high amount of over 40% by weight ratio of EVA added to LLDPE promotes dual peaks [11].…”

Section: Introductionmentioning

confidence: 99%

“…For example, the branch content of LLDPE was shown to have a noticeable effect on the blend's crystallization behavior; the higher the branch content, the higher the possibility of dual peak creation [9,13,14]. When a bimodal polyethylene was used in a blend with a wider blending ratio [19,20], a higher tendency to create dual peaks was observed. The heating rate can also affect DSC endothermic thermogram behaviors, so that at a rate of greater than 58C/min, multiple peaks can appear or can be more distinct [9,10,16].…”

Section: Introductionmentioning

confidence: 99%

Formation and characterization of polyethylene blends for autoclave‐based expanded‐bead foams

Behravesh

Park

Lee

2009

Polymer Engineering & Sci

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Blends of linear-low-density polyethylene (LLDPE), lowdensity polyethylene (LDPE), and high-density polyethylene (HDPE) were foamed and characterized in this research. The goal was to generate clear dual peaks from the expanded polyethylene (EPE) foam beads made from these blends in autoclave processing. Three blends were prepared in a twin-screw mixing extruder at two rotational speeds of 5 and 50 rpm: Blend1 (LLDPE with 20 wt% HDPE), Blend 2 (LLDPE with 20 wt% LDPE), and Blend 3 (LLDPE with 10 wt% HDPE and 10 wt% LDPE). The differential scanning calorimetric (DSC) measurement was taken at two cooling rates: 5 and 508C/min. Although no dual peaks were present, the results showed that blending with HDPE has a more noticeable effect on the DSC curve of LLDPE than blending with LDPE. Also, the rotational speed and cooling rate affected the shape of the DSC curves and the percentage area below the onset point. The DSC characterization of the batch foamed blends revealed multiple peaks at certain temperatures, which may be mainly due to the annealing effect during the gas saturation process.

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“…Pojêcie [1,2]. Obie wymienione frakcje [4], wy-stêpuj¹ce jednoczeoenie w równych stê¿eniach, powinny ró¿niae siê zdecydowanie modalnymi wartooeciami ciê¿aru cz¹steczkowego M 1 oraz M 2 , co pozwala na otrzymanie polimeru o bimodalnym rozk³adzie ciê¿aru cz¹steczkowego (rys. 1).…”

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“…1). Dwie mieszalne jego frakcje tworz¹ mieszaninê kompatybiln¹, o czym oewiadczy pojedynczy pik topnienia, oznaczany metod¹ analizy DSC [4].…”

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Selected properties of extruded bimodal high density polyethylene film

Frąszczak

Królikowski²

2009

Polimery

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Wybrane w³aoeciwooeci folii wyt³aczanej z polietylenu bimodalnego du¿ej gêstooeciStreszczenie -Na podstawie wyników badañ w³asnych oceniono kilka produkowanych w kraju rodzajów bimodalnego polietylenu du¿ej gêstooeci (Hostalen) i porównano je z odmian¹ PE unimodalnego (Tipelin, prod. wêgierskiej) pod wzglêdem w³aoeciwooeci mechanicznych, cieplnych oraz charakterystyki reologicznej (wartooeae MFR). Na podstawie przebiegów krzywych DSC granulatów i folii dokonano analizy przemian fazowych przebiegaj¹cych w polimerze w toku cyklu ogrzewanie-ch³odzenie-ogrzewanie. Stwierdzono czêoeciow¹ degradacjê spowodowan¹ przetwarzaniem granulatu w foliê (wyt³aczanie z rozdmuchiwaniem). Zjawisko to potwierdza równie¿ wzrost MFR folii w porównaniu z MFR granulatu. S³owa kluczowe: bimodalny polietylen du¿ej gêstooeci, folia, metoda DSC, przemiany fazowe. SELECTED PROPERTIES OF EXTRUDED BIMODAL HIGH DENSITY POLYETHYLENE FILMSummary -The evaluation of selected domestic bimodal high density polyethylene products (Hostalen, Table 1) was done on the basis of own research. Their mechanical and thermal properties as well as rheological characteristics (MFR values, Table 5) were compared with unimodal PE (Tipelin, made in Hungary). On the basis of DSC curves for granulates and films ( Fig. 3-12, Table 3 and 4), the analysis of phase transitions in a polymer during heating -cooling -heating cycle has been done. Partial degradation of the material during processing of granulate into film (blow molding - Fig. 2, Table 2) was found. The increase in MFR of the film in comparison with MFR of granulate also confirms the material degradation.

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Nonisothermal crystallization kinetics of linear bimodal–polyethylene (LBPE) and LBPE/low‐density polyethylene blends

Cited by 4 publications

References 8 publications

Study on the Phase Behavior of High Density Polyethylene – Ethylene Octene Copolymer Blends

Study on the Phase Behavior of High Density Polyethylene – Ethylene Octene Copolymer Blends

Formation and characterization of polyethylene blends for autoclave‐based expanded‐bead foams

Selected properties of extruded bimodal high density polyethylene film

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