Evaluation of LLDPE/LDPE blend foamability by in situ rheological measurements and bubble growth simulations

Chen, Yichong; Wan, Chengpeng; Liu, Tao; Chen, Zheqi; Qiao, Yida; Lu, Jiawei; Yan, Junyu; Zhao, Liang; Esseghir, Mohamed

doi:10.1016/j.ces.2018.07.051

Cited by 39 publications

(53 citation statements)

References 48 publications

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“…According to Gotsis's model, the relationship between the complex and the angular frequency could be expressed by the following equation:

η^{*} = \frac{G normalλ}{\sqrt{1 + {normalλ}^{2} {normalω}^{2}}}

where η * was the complex viscosity, ω is the angular frequency, G is the rigid modulus, and λ is the characteristic relaxation time.…”

Section: Resultsmentioning

confidence: 99%

“…And higher rigid modulus of LCB‐PA6 implied higher melt strength. During a polymer foaming process, the rigid modulus and the characteristic relaxation time are crucial factors to affect bubble growth and stability . Then, bubble growth simulation mainly based on these two properties to define and evaluate the foamability of modified PA6.…”

Section: Resultsmentioning

confidence: 99%

“…Some assumptions in this model and the principles of transfer processes (i.e., momentum transfer, mass transfer, and etc.) throughout the bubble‐growth period were detailedly described in previous work in our group …”

Section: Numerical Simulation Of Bubble Growth Dynamics and Stabilitymentioning

confidence: 99%

“…And the simulation revealed that the foamability of polymer was improved by introducing the LCB, which due to the well‐defined viscoelastic properties of the polymer melt. Chen et al . applied Gotsis's model to obtain characteristic relaxation time and rigid modulus from correlated rheological data, which were then substituted into single bubble model to analyze the bubble growth and stability.…”

Section: Introductionmentioning

confidence: 99%

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Determination of modified polyamide 6's foaming windows by bubble growth simulations based on rheological measurements

Chen

Liu

et al. 2019

J of Applied Polymer Sci

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Reactive extrusion was used to modify virgin polyamides 6 (v-PA6) and to prepare chain extended PA6 (CE-PA6) and longchain branched PA6 (LCB-PA6) for the melt foaming process. This was done using a twin-screw extruder and the following modifiers: a chain extender ADR-4368 and a branching agent maleic anhydride grafted polypropylene. A reaction mechanism was proposed to explain the chain extension and long-chain branching reactions and was verified by the Fourier transform infrared spectroscopy data. The analysis of the gel permeation chromatography data showed that LCB-PA6 presented a strong increase in the molecular weight and in the dispersity index. Moreover, the rheological properties of the v-PA6 and modified PA6 resins were characterized by a dynamic shear test. The LCB-PA6 compared with CE-PA6 showed much higher shear viscosity and longer characteristic relaxation times, indicating the presence of an LCB structure. A uniaxial elongation test showed that the LCB-PA6 had the highest melt viscosity and melt strength as well as most obvious strain-hardening behavior. A high-pressure differential scanning calorimeter under compressed CO 2 was used to investigate the PA6's crystallization properties so as to analyze its minimum temperature of foaming windows. The melt foamability of the CE-PA6 and the LCB-PA6 was verified by batch melt foaming experiments with CO 2 as the blowing agent and maximum temperature of foaming windows was also quantitatively determined by numerical simulation of bubble growth based on the rheological measurements. The results showed that the LCB-PA6 foams had a smaller cell diameter, a larger cell density, a greater expansion ratio, and wider foaming temperature window than the CE-PA6.

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“…According to Gotsis's model, the relationship between the complex and the angular frequency could be expressed by the following equation:

η^{*} = \frac{G normalλ}{\sqrt{1 + {normalλ}^{2} {normalω}^{2}}}

where η * was the complex viscosity, ω is the angular frequency, G is the rigid modulus, and λ is the characteristic relaxation time.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Numerical Simulation Of Bubble Growth Dynamics and Stabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Determination of modified polyamide 6's foaming windows by bubble growth simulations based on rheological measurements

Chen

Liu

et al. 2019

J of Applied Polymer Sci

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“…LLDPE is less shear sensitive due to its narrower molecular weight distribution and shorter chain branching, compared with conventional polyethylene. Chen et al . studied the foamability of LLDPE/LDPE blend by in situ rheological measurements and bubble growth simulations.…”

Section: Introductionmentioning

confidence: 99%

Density reduction behaviors and cell morphology in extrusion of LLDPE/wood fiber composites with physical and chemical blowing agents

Guo

2019

J of Applied Polymer Sci

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Foamed wood fiber/plastic composites (WPC) with a fine‐cell structure offer many benefits compared with the unfoamed WPC, such as the reduced material cost and density, the improved toughness, and the enhanced processability. However, it is extremely challenging to achieve the desired density reduction and obtain a fine‐cell structure simultaneously. One of the obstacles is that the volatiles released from the wood fiber (WF) during processing should be suppressed to ensure a fine‐cell structure. Linear low‐density polyethylene (LLDPE) has a relatively low melting temperature, and it can reduce the processing temperature and suppress volatiles when used as a polymer matrix for foamed WPC. This paper systematically investigates the foamability of LLDPE/WF composites in a continuous foam extrusion, with both a chemical blowing agent and a physical blowing agent (PBA). It turns out that the PBA‐based foaming led to a smaller cell size and a narrower cell size distribution. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48829.

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Microcellular PETs with High Expansion Ratio Produced by Supercritical CO₂ Molding Compression Foaming Process and Their Mechanical Properties

et al. 2022

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Supercritical CO 2 molding compression foaming is an emerging technology for preparing thick microcellular polymer sheets. In a temperature range of 245-255 C and CO 2 foaming pressure range of 5-20 MPa, the molding compression foaming behavior of polyethylene terephthalate (PET) is systematically studied. The maximum expansion ratio of the prepared PET foams is above 30, while the bubble size is only %20 μm. It is observed that during the foaming process, the temperature drop caused by rapid depressurization reaches up to 57 C, which greatly changes the viscoelasticity of PET and limits its foaming behavior. The nucleation and bubble growth behavior of PET is simulated and analyzed based on this change in viscoelasticity. Microcellular PET foams have excellent compression performance due to their smaller cell size and thinner cell wall, and the compression elastic modulus of the prepared microcellular PET sample is twice that of the extrusion foaming PET sample with a similar expansion ratio.

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Evaluation of LLDPE/LDPE blend foamability by in situ rheological measurements and bubble growth simulations

Cited by 39 publications

References 48 publications

Determination of modified polyamide 6's foaming windows by bubble growth simulations based on rheological measurements

Determination of modified polyamide 6's foaming windows by bubble growth simulations based on rheological measurements

Density reduction behaviors and cell morphology in extrusion of LLDPE/wood fiber composites with physical and chemical blowing agents

Microcellular PETs with High Expansion Ratio Produced by Supercritical CO₂ Molding Compression Foaming Process and Their Mechanical Properties

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Evaluation of LLDPE/LDPE blend foamability by in situ rheological measurements and bubble growth simulations

Cited by 39 publications

References 48 publications

Determination of modified polyamide 6's foaming windows by bubble growth simulations based on rheological measurements

Determination of modified polyamide 6's foaming windows by bubble growth simulations based on rheological measurements

Density reduction behaviors and cell morphology in extrusion of LLDPE/wood fiber composites with physical and chemical blowing agents

Microcellular PETs with High Expansion Ratio Produced by Supercritical CO2 Molding Compression Foaming Process and Their Mechanical Properties

Contact Info

Product

Resources

About

Microcellular PETs with High Expansion Ratio Produced by Supercritical CO₂ Molding Compression Foaming Process and Their Mechanical Properties