Crystallisation of single-site polyethylene blends investigated by thermal fractionation techniques

Chen, F; Shanks, Robert A.; Amarasinghe, Gandara

doi:10.1016/s0032-3861(00)00859-4

Cited by 46 publications

(20 citation statements)

References 32 publications

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“…Both methods were applied frequently for the characterization of the chain structure of PE in the last few decades. The effect of co-monomer type and content on the chain structure and the characterization of side branches were frequently the major goal of these measurements [6][7][8][9] (see Table 2 in reference [3] for more examples on the application of thermal fractionation methods). The chain structure of isotactic polypropylene has frequently also been characterized by thermal fractionation methods.…”

Section: Thermal Fractionation Of Polymersmentioning

confidence: 99%

Chain regularity of isotactic polypropylene determined by different thermal fractionation methods

Horváth

Menyhárd

Doshev

et al. 2014

J Therm Anal Calorim

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The chain regularity of isotactic polypropylene (iPP) homo-and random copolymers was characterized by different thermal fractionation methods in this study. Different stepwise temperature programs were applied in a calorimeter (DSC), in order to develop a method which is significantly faster than SIST and provides reliable information about the chain regularity of iPP. Our studies prove that self-seeding accelerates the crystallization process during annealing in SSA-DSC experiments (successive self-nucleation and annealing). Consequently, the time of isothermal steps can be shortened significantly in the SSA-DSC method. On the other hand we found that step time should not be too short if the goal of the measurement is the determination of average chain regularity. Our results clearly indicate that both the experimental conditions and the evaluation technique influence the obtained results. A standard experimental procedure is proposed for reliably determining the average chain regularity of iPP. The length of the SSA-DSC temperature program developed in this study is much shorter compared to that of the conventional SIST (stepwise isothermal segregation technique) measurements used recently for such experiments. The proposed SSA-DSC program makes the reliable characterization of a large number of samples on an acceptable timescale possible.

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Section: Thermal Fractionation Of Polymersmentioning

confidence: 99%

Chain regularity of isotactic polypropylene determined by different thermal fractionation methods

Horváth

Menyhárd

Doshev

et al. 2014

J Therm Anal Calorim

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“…These techniques include transmission electron spectroscopy, [8][9][10][11] small angle neutron scattering, [11][12][13] differential scanning calorimetry, 2,5,11,[14][15][16][17][18][19][20][21][22][23] rheology, 3,4,6,7,[16][17][18][24][25][26][27][28][29][30] X-ray diffraction 11,14,31 and more recently thermal fractionation techniques. 33,34 Mechanical characterization of polyolefin blends has also been a subject of interest. 2,[5][6][7][20][21][22][23][30][31][32] Molecular parameters like branch c...…”

mentioning

confidence: 99%

Melt Miscibility and Mechanical Properties of Metallocene LLDPE blends with HDPE: Influence of Mw of LLDPE

Hameed¹,

Hussein

2006

Polym J

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ABSTRACT:The influence of M w of LLDPE on the rheological, thermal and mechanical properties of m-LLDPE/ HDPE blends of low and high branch content (BC) was studied. Melt rheology of m-LLDPE blended with linear HDPE revealed strong influence of M w on melt miscibility at both branching levels. Low M w m-LLDPE/HDPE blends are suggested to be miscible at all compositions, while viscosity of high M w m-LLDPE/HDPE blends showed negative deviation from log additivity suggesting layered morphology of these blends. The DSC results suggest that compatibility in the solid state is independent of M w and BC. For all blends studied, the HDPE-rich blends were found to contain single crystal populations suggesting high degree of cocrystallization, whereas, m-LLDPE rich phase showed separate crystallization. The melt miscibility and the crystallization of high BC m-LLDPE blends with HDPE are suggested to be controlled by different factors. Small strain mechanical properties of these blends were found to be a strong function of blend compatibility and the specific properties of the blend components.[doi:10.1295/polymj.PJ2005254] KEY WORDS LLDPE/HDPE Blends / Miscibility / Rheology / Mechanical Properties / DSC / Molecular Weight / Polyethylene blends are widely used to improve processing and tailor properties.1-7 However, this enhancement of processing and properties is dictated by phase homogeneity or heterogeneity of these blends in the melt and solid state. A large number of studies utilizing different techniques were devoted to investigate the phase morphology and characterization of polyolefin blends. These techniques include transmission electron spectroscopy, [8][9][10][11] small angle neutron scattering, 11-13 differential scanning calorimetry, 2,5,11,[14][15][16][17][18][19][20][21][22][23] rheology, 3,4,6,7,[16][17][18][24][25][26][27][28][29][30] X-ray diffraction 11,14,31 and more recently thermal fractionation techniques. 33,34 Mechanical characterization of polyolefin blends has also been a subject of interest. 2,[5][6][7][20][21][22][23][30][31][32] Molecular parameters like branch content (BC), branch type, composition distribution, molecular weight (M w ) and molecular weight distribution (MWD) were found to be the key factors affecting the miscibility of polyolefin blends. Hill 9 using transmission electron spectroscopy (TEM) found that M w of linear HDPE had little influence on its miscibility with branched PEs. Alamo et al.12 observed that BC of the branched polyethylene (PE) is the most important parameter controlling the phase behavior of branched and linear PE blends. They reported no effect of M w of branched PE on its miscibility with linear polyethylene for M w $ 100 kg/mol. On the other hand, Tanem and Stori 10 reported strong influence of M w on miscibility of linear and branched PEs. They observed that low M w of m-LLDPE enhanced its miscibility with linear HDPE. Recently, the authors have extensively studied the influence of molecular parameters on the miscibility of different polyethylenes [21][2...

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“…The Hosoda relationship (Eq. 3), for LLDPE based on a catalyst system composed of MgCl 2 -supported TiCl 4 and triethylaluminum [40], is usually used by researchers [47][48][49]. A comparison between the calibrated relationship obtained here by 1 H NMR and the one calculated by Hosoda can be observed in Fig.…”

Section: Determination Of the Scb Contentmentioning

confidence: 70%

The interrelationships between microstructure and melting, crystallization and thermal degradation behaviors of fractionated ethylene/1-butene copolymer

et al. 2015

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Crystallisation of single-site polyethylene blends investigated by thermal fractionation techniques

Cited by 46 publications

References 32 publications

Chain regularity of isotactic polypropylene determined by different thermal fractionation methods

Chain regularity of isotactic polypropylene determined by different thermal fractionation methods

Melt Miscibility and Mechanical Properties of Metallocene LLDPE blends with HDPE: Influence of Mw of LLDPE

The interrelationships between microstructure and melting, crystallization and thermal degradation behaviors of fractionated ethylene/1-butene copolymer

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