Effect of polymerization time on the molecular weight and molecular weight distribution of polypropylene

Abedi, Sadegh; Hosseinzadeh, Mehdi; Kazemzadeh, M.A.; Daftari‐Besheli, Majid

doi:10.1002/app.23123

Cited by 8 publications

(1 citation statement)

References 11 publications

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“…It is also seen that molecular weight of the EPR and EPS fractions slightly increased with an increase in t gas ; however, the molecular weight of iPP is almost constant. This phenomenon is similar to the change of molecular weight of PP with polymerization time reported in literature …”

Section: Resultssupporting

confidence: 91%

Synthesis of Polypropylene/Poly(ethylene-co-propylene) In-Reactor Alloys by Periodic Switching Polymerization Process—Effects of Gas Phase Polymerization Time on Polymer Properties

Mehtarani

Fan

et al. 2013

Ind. Eng. Chem. Res.

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A series of polypropylene/poly(ethylene-co-propylene) in-reactor alloys was prepared by a periodic switching polymerization process (PSPP) in which the monomer feed was periodically switched between pure propylene and an ethylene/ propylene mixture using a commercial TiCl 4 /MgCl 2 /phthalate−Al(C 2 H 5 ) 3 /DCPDMS Ziegler−Natta catalyst. In this work, the influence of the total time of gas phase PSPP (t gas ) on the composition, morphology, and properties of the alloys were investigated. The rate of copolymer production was almost constant in the gas phase PSPP reaction for as long as 2 h, implying that the diffusion barrier does not significantly increase with t gas in the gas phase PSPP. By fractionating the PP/EPR alloys to three fractions, random ethylene/propylene copolymer (EPR), segmented ethylene/propylene copolymer (EPS), and isotactic polypropylene (iPP), it was found that the EPR and EPS content of the alloys increased with increasing t gas. The chain structure of the fractions also changed with an increase in t gas . An increase in t gas led to a decrease in the content of [PPP] and [EEE] triads in EPS fraction, but the influence of t gas on the sequence distributions of EPR fractions can be ignored. The average size of the dispersed phase domains or EPR domains increased first and then leveled off with increase in t gas . The number of EPR domains increased with an increase in t gas . Toughness of the alloy was improved by prolonging PSPP. The impact strength at low temperature (−20 °C) was more sensitive to the EPR content than that at room temperature. The flexural modulus was sensitive to the EPS content. The toughness−stiffness balance of the alloy is significantly influenced by both t gas and the switching frequency of PSPP.

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Section: Resultssupporting

confidence: 91%

Synthesis of Polypropylene/Poly(ethylene-co-propylene) In-Reactor Alloys by Periodic Switching Polymerization Process—Effects of Gas Phase Polymerization Time on Polymer Properties

Mehtarani

Fan

et al. 2013

Ind. Eng. Chem. Res.

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Efficient Transesterification Preparation of Polycarbonate Diol with High Molecular Weight Using TiO₂/SiO₂ Solid Acid Catalysts

Chong

Qian²,

Wei

et al. 2023

ChemistrySelect

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A series of TiO2/SiO2 catalysts were prepared by hydrolysis and used in the transesterification of diphenyl carbonate (DPC) and 1,4‐butanediol (BDO) to produce polycarbonate diol (PCDL). The physical properties of TiO2/SiO2 solid acid catalysts were characterized, and the relationship between their structural features and catalytic transesterification reaction was analyzed. The effects of various reaction conditions such as hydrolysis procedure, transesterification temperature, catalyst amount, and the mole ratio of the starting materials on the catalytic synthesis of PCDL were investigated. The maximum catalytic activity was based on the TiO2 : SiO2=3 : 1 with hydrolysis procedure of adding the Ti/Si mixture (A) to deionized water and anhydrous ethanol (B). The as‐synthesized TiO2/SiO2‐A‐to‐B catalyst exhibits rough surface with the average pore size of 6.75 nm, and the total acid amount of 1.07 mmol/g. The PCDL yield of transesterification reached 89.8 %, and the number average molecular weight reached 9074 g/mol under the optimal reaction conditions, and the molecular weight of the PCDL product could be adjusted.

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Control of molecular weight distribution for polypropylene obtained by commercial Ziegler–Natta catalyst: effect of temperature

et al. 2011

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Effect of polymerization time on the molecular weight and molecular weight distribution of polypropylene

Cited by 8 publications

References 11 publications

Synthesis of Polypropylene/Poly(ethylene-co-propylene) In-Reactor Alloys by Periodic Switching Polymerization Process—Effects of Gas Phase Polymerization Time on Polymer Properties

Synthesis of Polypropylene/Poly(ethylene-co-propylene) In-Reactor Alloys by Periodic Switching Polymerization Process—Effects of Gas Phase Polymerization Time on Polymer Properties

Efficient Transesterification Preparation of Polycarbonate Diol with High Molecular Weight Using TiO₂/SiO₂ Solid Acid Catalysts

Control of molecular weight distribution for polypropylene obtained by commercial Ziegler–Natta catalyst: effect of temperature

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Effect of polymerization time on the molecular weight and molecular weight distribution of polypropylene

Cited by 8 publications

References 11 publications

Synthesis of Polypropylene/Poly(ethylene-co-propylene) In-Reactor Alloys by Periodic Switching Polymerization Process—Effects of Gas Phase Polymerization Time on Polymer Properties

Synthesis of Polypropylene/Poly(ethylene-co-propylene) In-Reactor Alloys by Periodic Switching Polymerization Process—Effects of Gas Phase Polymerization Time on Polymer Properties

Efficient Transesterification Preparation of Polycarbonate Diol with High Molecular Weight Using TiO2/SiO2 Solid Acid Catalysts

Control of molecular weight distribution for polypropylene obtained by commercial Ziegler–Natta catalyst: effect of temperature

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Efficient Transesterification Preparation of Polycarbonate Diol with High Molecular Weight Using TiO₂/SiO₂ Solid Acid Catalysts