Influence of pressure-induced temperature drop on the foaming behavior of amorphous polylactide (PLA) during autoclave foaming with supercritical CO2

Dippold, Marcel; Ruckdäschel, Holger

doi:10.1016/j.supflu.2022.105734

Cited by 7 publications

(5 citation statements)

References 45 publications

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“…Pressure-induced foaming is the most used variant in batch foaming processes. Several processing parameters of the pressure-induced batch foaming process have a strong influence on the final foam properties [141,142]. These include (i) the saturation pressure, at the stage of saturation with the blowing agent, which controls the solubility of the blowing agent; (ii) the temperature, which affects the chain mobility and hence the crystallization behaviour; (iii) the saturation time, which also affects the amount of blowing agent dissolved in the polymer and hence the corresponding plasticizing effect on the polymer; and finally, (iv) the pressure drop, which impacts on the nucleation rate and the overall foaming process [143].…”

Section: Pressure-induced Batch Foamingmentioning

confidence: 99%

Forefront Research of Foaming Strategies on Biodegradable Polymers and Their Composites by Thermal or Melt-Based Processing Technologies: Advances and Perspectives

Gonçalves,

Reis,

Fernandes

2024

Polymers

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The last few decades have witnessed significant advances in the development of polymeric-based foam materials. These materials find several practical applications in our daily lives due to their characteristic properties such as low density, thermal insulation, and porosity, which are important in packaging, in building construction, and in biomedical applications, respectively. The first foams with practical applications used polymeric materials of petrochemical origin. However, due to growing environmental concerns, considerable efforts have been made to replace some of these materials with biodegradable polymers. Foam processing has evolved greatly in recent years due to improvements in existing techniques, such as the use of supercritical fluids in extrusion foaming and foam injection moulding, as well as the advent or adaptation of existing techniques to produce foams, as in the case of the combination between additive manufacturing and foam technology. The use of supercritical CO2 is especially advantageous in the production of porous structures for biomedical applications, as CO2 is chemically inert and non-toxic; in addition, it allows for an easy tailoring of the pore structure through processing conditions. Biodegradable polymeric materials, despite their enormous advantages over petroleum-based materials, present some difficulties regarding their potential use in foaming, such as poor melt strength, slow crystallization rate, poor processability, low service temperature, low toughness, and high brittleness, which limits their field of application. Several strategies were developed to improve the melt strength, including the change in monomer composition and the use of chemical modifiers and chain extenders to extend the chain length or create a branched molecular structure, to increase the molecular weight and the viscosity of the polymer. The use of additives or fillers is also commonly used, as fillers can improve crystallization kinetics by acting as crystal-nucleating agents. Alternatively, biodegradable polymers can be blended with other biodegradable polymers to combine certain properties and to counteract certain limitations. This work therefore aims to provide the latest advances regarding the foaming of biodegradable polymers. It covers the main foaming techniques and their advances and reviews the uses of biodegradable polymers in foaming, focusing on the chemical changes of polymers that improve their foaming ability. Finally, the challenges as well as the main opportunities presented reinforce the market potential of the biodegradable polymer foam materials.

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Section: Pressure-induced Batch Foamingmentioning

confidence: 99%

Forefront Research of Foaming Strategies on Biodegradable Polymers and Their Composites by Thermal or Melt-Based Processing Technologies: Advances and Perspectives

Gonçalves,

Reis,

Fernandes

2024

Polymers

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Section: Expanded Polylactic Acid (Epla) Beadsmentioning

confidence: 99%

“…On the other hand, the foaming and cooling steps would destroy parts of the crystals and induce the formation of the low melting peak. Additionally, Ruckdäschel et al [66] studied the influence of different saturation conditions on the density and cell morphology of amorphous PLA. It was reported that the initial pressure drop rate had a dramatic influence on the nucleation density and that the desirable cell morphology could be obtained by selective modification of foaming conditions.…”

Section: Expanded Polylactic Acid (Epla) Beadsmentioning

confidence: 99%

Polymer Bead Foams: A Review on Foam Preparation, Molding, and Interbead Bonding Mechanism

Jiang,

Wang,

Tian

et al. 2023

Macromol

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The diverse physical appearances and wide density range of polymer bead foams offer immense potential in various applications and future advancements. The multiscale and multilevel structural features of bead foams involve many fundamental scientific topics. This review presents a comprehensive overview of recent progress in the preparation and molding techniques of bead foams. Firstly, it gives a comparative analysis on the bead foam characteristics of distinct polymers. Then, a summary and comparison of molding techniques employed for fabricating bead foam parts are provided. Beyond traditional methods like steam-chest molding (SCM) and adhesive-assisted molding (AAM), emerging techniques like in-mold foaming and molding (IMFM) and microwave selective sintering (MSS) are highlighted. Lastly, the bonding mechanisms behind these diverse molding methods are discussed.

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“…Additionally, the saturation of the foaming agent in the polymer occurs before the extrusion foaming process, eliminating the need for shear mixing of the polymer and foaming agent by the screw. This enables MEF to achieve a more dense and uniform cellular structure [ 101 , 102 , 103 ].…”

Section: Mefmentioning

confidence: 99%

A Review of the Preparation of Porous Fibers and Porous Parts by a Novel Micro-Extrusion Foaming Technique

Wang,

Huang,

Wang

et al. 2023

Materials

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This review introduces an innovative technology termed “Micro-Extrusion Foaming (MEF)”, which amalgamates the merits of physical foaming and 3D printing. It presents a groundbreaking approach to producing porous polymer fibers and parts. Conventional methods for creating porous materials often encounter obstacles such as the extensive use of organic solvents, intricate processing, and suboptimal production efficiency. The MEF technique surmounts these challenges by initially saturating a polymer filament with compressed CO2 or N2, followed by cell nucleation and growth during the molten extrusion process. This technology offers manifold advantages, encompassing an adjustable pore size and porosity, environmental friendliness, high processing efficiency, and compatibility with diverse polymer materials. The review meticulously elucidates the principles and fabrication process integral to MEF, encompassing the creation of porous fibers through the elongational behavior of foamed melts and the generation of porous parts through the stacking of foamed melts. Furthermore, the review explores the varied applications of this technology across diverse fields and imparts insights for future directions and challenges. These include augmenting material performance, refining fabrication processes, and broadening the scope of applications. MEF technology holds immense potential in the realm of porous material preparation, heralding noteworthy advancements and innovations in manufacturing and materials science.

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Influence of pressure-induced temperature drop on the foaming behavior of amorphous polylactide (PLA) during autoclave foaming with supercritical CO2

Cited by 7 publications

References 45 publications

Forefront Research of Foaming Strategies on Biodegradable Polymers and Their Composites by Thermal or Melt-Based Processing Technologies: Advances and Perspectives

Forefront Research of Foaming Strategies on Biodegradable Polymers and Their Composites by Thermal or Melt-Based Processing Technologies: Advances and Perspectives

Polymer Bead Foams: A Review on Foam Preparation, Molding, and Interbead Bonding Mechanism

A Review of the Preparation of Porous Fibers and Porous Parts by a Novel Micro-Extrusion Foaming Technique

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