Mechanical Properties of Microcellular and Nanocellular Thermoplastic Polyurethane Nanocomposite Foams Created Using Supercritical Carbon Dioxide

Yeh, Shu‐Kai; Liu, Yu-Che; Chu, Chien‐Chia; Chang, Kung‐Chin; Wang, Sea-Fue

doi:10.1021/acs.iecr.7b00942

Cited by 49 publications

(27 citation statements)

References 61 publications

(108 reference statements)

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“…Over the whole strain area, pure HPL (E C = 7.40 ± 0.69 MPa, σ 50 = 12.16 ± 1.37 MPa, Table 3 ) had a significantly higher compression modulus (E C ) and compressive stress at 50% compressive strain (σ 50 ) than HPB (E C = 5.34 ± 0.98 MPa, σ 50 = 7.75 ± 0.37 MPa), since HPL had a higher fraction of hard segments [ 81 , 82 ]. As known from thermoplastic/elastomeric foams [ 104 ] and in particular from TPU foams [ 87 , 105 ], the relative density shows a direct correlation with E C and σ 50 . This trend is also valid for the present work.…”

Section: Resultsmentioning

confidence: 73%

Development of Porous Polyurethane Implants Manufactured via Hot-Melt Extrusion

et al. 2020

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Implantable drug delivery systems (IDDSs) offer good patient compliance and allow the controlled delivery of drugs over prolonged times. However, their application is limited due to the scarce material selection and the limited technological possibilities to achieve extended drug release. Porous structures are an alternative strategy that can overcome these shortcomings. The present work focuses on the development of porous IDDS based on hydrophilic (HPL) and hydrophobic (HPB) polyurethanes and chemical pore formers (PFs) manufactured by hot-melt extrusion. Different PF types and concentrations were investigated to gain a sound understanding in terms of extrudate density, porosity, compressive behavior, pore morphology and liquid uptake. Based on the rheological analyses, a stable extrusion process guaranteed porosities of up to 40% using NaHCO3 as PF. The average pore diameter was between 140 and 600 µm and was indirectly proportional to the concentration of PF. The liquid uptake of HPB was determined by the open pores, while for HPL both open and closed pores influenced the uptake. In summary, through the rational selection of the polymer type, the PF type and concentration, porous carrier systems can be produced continuously via extrusion, whose properties can be adapted to the respective application site.

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Section: Resultsmentioning

confidence: 73%

Development of Porous Polyurethane Implants Manufactured via Hot-Melt Extrusion

et al. 2020

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“…The addition of nanoparticles is therefore a promising method to enhance the mechanical performance of nanocellular polymers. In the recent work of Yeh et al, the addition of nanoclays was proved to enhance the modulus and yield strength of nanocellular TPU. However, the authors have been unable to locate any more studies that investigate the effect of nanoparticles on the mechanical properties of nanocellular polymers.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of PMMA‐Sepiolite Nanocellular Materials with a Bimodal Cellular Structure

Bernardo

Loock

León

et al. 2019

Macro Materials & Eng

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Bimodal cellular poly(methyl methacrylate) with micro‐ and nano‐sized (300–500 nm) cells with up to 5 wt% of sepiolite nanoparticles and porosity from 50% to 75% are produced by solid‐state foaming. Uniaxial compression tests are performed to measure the effect of sepiolite concentration on the elastic modulus and the yield strength of the solid and cellular nanocomposites. Single edge notch bend tests are conducted to relate the fracture toughness of the solid and cellular nanocomposites to sepiolite concentration. The relative modulus is independent of sepiolite content to within material scatter when considering the complete porosity range. In contrast, a mild enhancement of the relative modulus is observed by the addition of sepiolite particles for the foamed nanocomposites with a porosity close to 50%. The relative compressive strength of the cellular nanocomposites mildly decreases as a function of sepiolite concentration. A strong enhancement of the relative fracture toughness by the addition of sepiolites is observed. The enhancement of the relative fracture toughness and the relative modulus (at 50% porosity) can be attributed to an improved dispersion of the particles due to foaming and the migration of micro‐sized aggregates from the solid phase to the microcellular pores during foaming.

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“…Despite the exciting properties of nanocellular polymers, its production is still nowadays a challenging task for scientists around the world. On the one hand, the production of nanocellular polymers has been achieved for different polymer matrices such as polymethylmethacrylate (PMMA) [ 30 ], polycarbonate (PC) [ 31 ], thermoplastic polyurethane (TPU) [ 32 ], polyetherimide (PEI) [ 33 ], and polyphenylsulfone (PPSU) [ 34 ], but there exist many other systems, such as polystyrene (PS), in which the production of nanocells has not yet been reported. Moreover, the production of nanocellular polymers in the large scale is not yet a reality due to the difficult task of producing large and homogeneous parts of such materials.…”

Section: Production Of Nanocellular Polymersmentioning

confidence: 99%

“…PPSU has been proven to present also small cell sizes (21 nm), but the cell nucleation density in this material is still small in comparison with the PMMA, and its relative density is also higher (0.7) [ 34 ]. Finally, for nanocellular materials based on thermoplastic polyurethane, the smaller reported cell size is 450 nm with relative densities as high as 0.94 [ 32 ].…”

Section: Limits and Future Trendsmentioning

confidence: 99%

Nanocellular Polymers: The Challenge of Creating Cells in the Nanoscale

2019

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The evolution of technology means that increasingly better materials are needed. It is well known that as a result of their interesting properties, nanocellular polymers perform better than microcellular ones. For this reason, the investigation on nanocellular materials is nowadays a very topical issue. In this paper, the different approaches for the production of these materials in our laboratory are explained, and results obtained by using polymethylmethacrylate (PMMA) are shown. Homogeneous nucleation has been studied by using raw PMMA, while two different systems were used for heterogeneous nucleation; adding nanoparticles to the system and using nanostructured polymers as solid precursors for foaming. The effects of the different parameters of the production process (gas dissolution foaming process) have been evaluated for all systems being possible to establish a comparison between the materials produced by different approaches. Moreover, the limitations and future work to optimise the materials produced are also discussed.

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Mechanical Properties of Microcellular and Nanocellular Thermoplastic Polyurethane Nanocomposite Foams Created Using Supercritical Carbon Dioxide

Cited by 49 publications

References 61 publications

Development of Porous Polyurethane Implants Manufactured via Hot-Melt Extrusion

Development of Porous Polyurethane Implants Manufactured via Hot-Melt Extrusion

Mechanical Properties of PMMA‐Sepiolite Nanocellular Materials with a Bimodal Cellular Structure

Nanocellular Polymers: The Challenge of Creating Cells in the Nanoscale

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