Crystallization Elution Fractionation. A New Separation Process for Polyolefin Resins

Monrabal, Benjamín; Sancho-Tello, Juan; Mayo, N.; Romero, L.

doi:10.1002/9783527623679.ch6

Cited by 22 publications

(28 citation statements)

References 4 publications

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“…Actually, it reflects a typical assembling structure of thermoplastic elastomers and explains why homogeneous copolymers usually show high elasticity, as is the case with low-crystallinity ethylene-1-octene copolymers. 68 The master crystallinity curves as a function of temperature for melting and crystallization can play a role as a phase diagram in fractionation analysis, and hence be useful to clarify the principles of temperature rising elution fractionation (TREF), 69,70 crystallization analysis fractionation (CRYSTAF), 71 and other fractionation methods based on crystallization/dissolution. 1,23 TREF has been widely used to analyze the comonomer distribution within the molecules and to prepare copolymer fractions with narrow-distributed comonomer contents.…”

Section: Discussionmentioning

confidence: 99%

Phase Transitions of Bulk Statistical Copolymers Studied by Dynamic Monte Carlo Simulations

Mathot

Frenkel

2003

Macromolecules

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We report a numerical study of crystallization and melting in bulk statistical homogeneous (random), homogeneous (slightly alternating), and heterogeneous (produced in a batch reaction) copolymers formed by crystallizable monomers and noncrystallizable comonomers. In our dynamic Monte Carlo simulations of lattice chains, the current model further assumes that the comonomers cannot move into crystalline regions by sliding diffusion of the chains. We find that both the overall composition and the statistical distribution of the monomers affect the phase-transition temperature, the resulting relative crystallinity, and the crystal morphology. However, the final absolute crystallinity of homogeneous copolymers seems insensitive to these parameters. Intramolecular segregation between monomers and comonomers is accompanied by crystallization, demonstrating the concept of sequence segregation or nanophase separation of statistical copolymers with assembling structures like in thermoplastic elastomers. Moreover, if crystallization of homogeneous copolymers has started but not yet completed on cooling, subsequent heating will show cold crystallization before melting, which can be attributed to insertion-mode lamellar growth. For heterogeneous copolymers, intermolecular segregation occurs on cooling before crystallization. On the basis of our observations, a pair of master melting and crystallization curves for the crystallinity of a statistical copolymer as a function of temperature are suggested to reflect the characteristic of the monomer-sequence-length distribution. This suggestion facilitates the clarification to the kinetic disturbance in local temperature regions and to the principle of some fractionation methods, such as temperature rising elution fractionation (TREF).

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Section: Discussionmentioning

confidence: 99%

Phase Transitions of Bulk Statistical Copolymers Studied by Dynamic Monte Carlo Simulations

Mathot

Frenkel

2003

Macromolecules

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“…The crystallization is carried out in stirred stainless steel reactors of 60 mL volume where dissolution and filtration takes place automatically, as it has been reported previously. 19,34 Up to five crystallization reactors can be installed in the main oven. The infrared detector used is a dual wavelength optoelectronic unit with a heated flow-through micro cell operating at 150°C and using 3.5 as the measuring wavelength.…”

Section: Crystaf Analysismentioning

confidence: 99%

“…19,20 In CRYSTAF, the polymer composition is obtained in a single crystallization cycle by monitoring the solution concentration depression as temperature goes down ; typical analysis time is around 6 h for five simultaneous samples. TREF, on the other hand, demands in addition to the crystallization step a second temperature cycle (elution step) to obtain the information on polymer composition; typical analysis time is a sample per day.…”

Section: Theoreticalmentioning

confidence: 99%

Characterization of homogeneous ethylene/1‐octene copolymers made with a single‐site catalyst. CRYSTAF analysis and calibration

Monrabal

Blanco²,

Nieto

et al. 1999

J. Polym. Sci. A Polym. Chem.

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“…As resinas ZN-1 e ZN-2 apresentaram curvas típicas de PELBD catalisados com Ziegler-Natta [16,17] com três regiões distintas: uma entre ~72 °C e 88 °C, representando as populações de [5] ; quanto mais estreita a DPM menos pseudoplástico é o polímero fundido. , o inchamento do extrudado aumenta com a taxa de cisalhamento e que as resinas ZN's apresentam inchamentos superiores aos da resina metalocênica, comportamentos estes similares ao comportamento da N 1 ( ).…”

Section: Resultsunclassified

Correlação entre propriedades reológicas e ópticas de filmes tubulares de polietileno linear de baixa densidade com diferentes distribuições de ramificações curtas

et al. 2006

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Resumo: Devido a suas excelentes propriedades mecânicas o polietileno linear de baixa densidade, PELBD, tem ganhado cada vez mais importância na indústria de embalagens. Essas propriedades são resultado de sua estrutura molecular, da existência de ramificações curtas, SCB, e da distribuição dessas ramificações, DSCB. Junto com o peso molecular, PM, e sua distribuição, DPM, as ramificações curtas também afetam o processo de sopro de filmes influenciando na solidificação do filme até a linha de neve, já que a cinética de cristalização é dependente da distribuição destas ramificações. Assim, este trabalho teve como objetivo verificar a influência da DSCB do PELBD nas propriedades reológicas e óticas de filmes tubulares. Para isso, três PELBD foram escolhidos; dois sintetizados com catalisador Ziegler-Natta e um com catalisador metaloceno, de peso molecular ponderal médio, M w , similar e DSCB diferentes.Observou-se que a DSCB exerce influência nas propriedades reológicas que refletem a elasticidade do material como a primeira diferença de tensões normais N 1 , o módulo de armazenamento G'(ω), e a deformação recuperável γ r ; entretanto na viscosidade em função da taxa de cisalhamento η( ), e no módulo de perda G"(ω), a diferença nessa distribuição não foi percebida. Observou-se também que quanto maior a deformação recuperável dos PELBD, menores foram as estruturas cristalinas formadas o que diminuiu a opacidade dos filmes. Porém essa proporcionalidade manteve-se até uma determinada γ r mínima, acima da qual a fratura do fundido se sobrepôs à recuperação da deformação e a opacidade voltou a aumentar. Palavras-chave: Polietileno linear de baixa densidade, filmes soprados, deformação recuperável, opacidade. Correlation Between Rheological and Optical Properties of LLDPE Blown Films with Different Distributions of Short Chain BranchingAbstract: Linear low-density polyethylene, LLDPE, has increased its market share in the packaging industry due to its excellent mechanical properties. These properties are the result of its molecular structure due to its short chain branching, SCB, and their distribution, DSCB. Together with the molecular weight and the distribution of molecular weights, the SCB affects the blown film process because it interferes in the film solidification and crystallization kinetics up to the freezing line. The objective of this work was to verify the influence of the DSCB of LLDPE in the rheological and optical properties of blown films. Three LLDPE, synthesized with Ziegler-Natta and metallocene catalysts, were studied, all with similar weight average molecular weight, M w , but with different DSCB. It was observed that the DSCB influenced the rheological properties that reflect the material elasticity, such as the first normal tension difference, N 1 ( ), the storage modulus G'(w) and the recoverable strain γ r ; however, the rheological properties that reflect the viscosity, such as the shear viscosity η( ) and the loss modulus G"(w), were not affected. In addition, the higher the γ r of the LLDPE,...

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Crystallization Elution Fractionation. A New Separation Process for Polyolefin Resins

Cited by 22 publications

References 4 publications

Phase Transitions of Bulk Statistical Copolymers Studied by Dynamic Monte Carlo Simulations

Phase Transitions of Bulk Statistical Copolymers Studied by Dynamic Monte Carlo Simulations

Characterization of homogeneous ethylene/1‐octene copolymers made with a single‐site catalyst. CRYSTAF analysis and calibration

Correlação entre propriedades reológicas e ópticas de filmes tubulares de polietileno linear de baixa densidade com diferentes distribuições de ramificações curtas

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