Predictions of the Thermodynamic Properties of Multicomponent Polyolefin Blends from Measurements on Two-Component Systems

Jeon, Hee Jung; Lee, J. H.; Balsara, Nitash P.

doi:10.1021/ma9709718

Cited by 46 publications

(115 citation statements)

References 41 publications

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“…10,18,48,49 These fluctuations are described by a matrix of partial structure factors S(q) (q is the scattering vector) that describe correlations between different components in the system. Homogeneous systems have det[S(q)] > 0 for all values of q.…”

Section: Introductionmentioning

confidence: 99%

Microphase and Macrophase Separation in Multicomponent A/B/A−C Polymer Blends with Attractive and Repulsive Interactions

et al. 2006

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A balanced A-C diblock copolymer surfactant was used to organize mixtures of immiscible A and B homopolymers. The C block of the copolymer exhibits repulsive and attractive interactions with the A and B homopolymers, respectively, leading to rich phase behavior. Experimental results indicate the existence of a microphase-separated state at low temperatures, a homogeneous phase at intermediate temperatures, and macrophase separation at high temperatures. It is unusual for a microphase-separated blend to exhibit a homogeneous phase prior to macrophase separation. In this study, component A was saturated polybutadiene with 89% 1,2-addition, component B was polyisobutylene, block A of the diblock copolymer was chemically equivalent to component A, and block C of the diblock copolymer was saturated polybutadiene with 63% 1,2-addition. We use a combination of Flory-Huggins theory (FHT), self-consistent field theory (SCFT) and the random-phase approximation (RPA) to understand the origin of our observations. All of the parameters needed for the SCFT, FHT, and RPA calculations were obtained from independent measurements. The measured length scale of the periodic concentration fluctuations in the homogeneous state and the domain spacing of the microphase-separated blends were in close agreement with RPA and SCFT, respectively. The transition temperatures between phases predicted with theory were in reasonable agreement with the experimental measurements.

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Section: Introductionmentioning

confidence: 99%

Microphase and Macrophase Separation in Multicomponent A/B/A−C Polymer Blends with Attractive and Repulsive Interactions

et al. 2006

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“…Thus, the presence of azimuthally anisotropic SANS profiles is an indication of the presence of an anisotropic ordered phase (e.g., a lamellar phase). 58 In ref 37 we determined the orderdisorder transition temperature of pure PE-PP (the same block copolymer used in this study) to be 149.5 ( 1.5°C by noting the temperature at which the azimuthal anisotropy was lost.…”

Section: Resultsmentioning

confidence: 99%

“…33,36,37 The distinguishing feature of the present work is the presence of three chemically distinct components with qualitatively different ij parameters.…”

Section: Theory Of Scattering From Homogeneous Mixturesmentioning

confidence: 91%

“…37,38 This paper is part of a series on the subject of concentration fluctuations and phase behavior of complex polymer blends. [33][34][35][36][37] Most of our previous work 33,34,36,37 is restricted to blends with repulsive interactions only. In a recent paper we studied blends of polyisobutylene (PIB), polyethylene (PE), and a poly-(ethylene-block-head-to-head propylene) copolymer (PE-PP).…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamics and Phase Behavior of Block Copolymer/Homopolymer Blends with Attractive and Repulsive Interactions

et al. 2002

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Small-angle neutron scattering (SANS) experiments were conducted on a 25 vol % blend of a poly(ethylene-block-head-to-head propylene) copolymer (PE-PP) in polyisobutylene (PIB). PE/PIB and PE/PP chains are incompatible (the Flory-Huggins interaction parameter > 0), while PIB and PP are compatible ( < 0) at low temperatures and incompatible ( > 0) at high temperatures. These interactions lead to an order-disorder transition at 150 ( 5°C and macrophase separation at 251 ( 5°C. The nature of the concentration fluctuations in the homogeneous state (155°C < T < 246°C) was studied by comparing the experimentally determined SANS profiles with theoretical calculations based on the multicomponent random phase approximation (RPA). Order formation at low temperatures is driven by two parameters:PE/PIB and lPP (the statistical segment length of the PP block). The other temperature-dependent parameters drive the system away from the ordering transition. At high temperatures, the RPA predicts microphase separation, while experimental data (neutron and light scattering) indicate macrophase separation. This discrepancy is mainly due to the inability of the RPA to correctly account for the large length scale concentration fluctuations.

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“…The roles of AB diblock copolymers on the equilibrium, bulk properties in A/B blends are relatively well understood: The diblocks can either act as surfactants to lower the interfacial tension by adsorbing at the A/B interface, or serve as co-solvent and distribute uniformly throughout the blends to improve their compatibility, or phase separate into a new copolymer-rich phase. [6][7][8][9][10] However, there has been no theoretical work that elucidates the roles of the diblocks in the nucleation event that leads to phase separation. Therefore, our study will nicely complement previous theoretical work on the equilibrium, bulk properties, and will provide the theoretical basis for controlling the nucleation behavior in A/B blends by the addition of the AB diblock copolymers.…”

Section: Introductionmentioning

confidence: 99%

Nucleation in binary polymer blends: Effects of adding diblock copolymers

Wang

Zhang

Qiu

et al. 2003

The Journal of Chemical Physics

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The effects of adding AB diblock copolymers to A/B binary blends on the structure and thermodynamics of critical nuclei are studied using the self-consistent field theory. At a fixed ratio of the amount of the two homopolymers, depending on the degree of polymerization and composition of the diblocks, their addition to the blends can either increase or decrease the nucleation free energy barrier relative to the pure A/B blends. The qualitative trend can be deduced from the shift in the coexistence boundary and the spinodal. The distribution of diblock copolymers in critical nuclei depends on the composition of the diblocks and the quench depth. Near the coexistence, symmetric diblocks exhibit surfactant behavior, being highly concentrated on the interface of the critical nuclei. Near the spinodal, they act more like co-solvent with a relatively uniform distribution.

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Predictions of the Thermodynamic Properties of Multicomponent Polyolefin Blends from Measurements on Two-Component Systems

Cited by 46 publications

References 41 publications

Microphase and Macrophase Separation in Multicomponent A/B/A−C Polymer Blends with Attractive and Repulsive Interactions

Microphase and Macrophase Separation in Multicomponent A/B/A−C Polymer Blends with Attractive and Repulsive Interactions

Thermodynamics and Phase Behavior of Block Copolymer/Homopolymer Blends with Attractive and Repulsive Interactions

Nucleation in binary polymer blends: Effects of adding diblock copolymers

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