Experimental-numerical studies of the effect of cell structure on the mechanical properties of polypropylene foams

Gong, Wei; Jiang, Tuanhui; Zeng, Xiangbu; He, Li; Zhang, Chun

doi:10.1515/epoly-2020-0060

Cited by 12 publications

(5 citation statements)

References 26 publications

(27 reference statements)

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“…In general, the mechanical properties of foams, in terms of elastic modulus and stress values, were greatly influenced by cell morphology. Typically, these properties increased with decreasing cell size and increasing in closed pore content and vice versa, as widely studied by [ 65 , 66 ].…”

Section: Resultsmentioning

confidence: 99%

Effect of Different Methods to Synthesize Polyol-Grafted-Cellulose Nanocrystals as Inter-Active Filler in Bio-Based Polyurethane Foams

et al. 2023

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Currently, the scientific community has spent a lot of effort in developing “green” and environmentally friendly processes and products, due the contemporary problems connected to pollution and climate change. Cellulose nanocrystals (CNCs) are at the forefront of current research due to their multifunctional characteristics of biocompatibility, high mechanical properties, specific surface area, tunable surface chemistry and renewability. However, despite these many advantages, their inherent hydrophilicity poses a substantial challenge for the application of CNCs as a reinforcing filler in polymers, as it complicates their dispersion in hydrophobic polymeric matrices, such as polyurethane foams, often resulting in aggregate structures that compromise their properties. The manipulation and fine-tuning of the interfacial properties of CNCs is a crucial step to exploit their full potential in the development of new materials. In this respect, starting from an aqueous dispersion of CNCs, two different strategies were used to properly functionalize fillers: (i) freeze drying, solubilization in DMA/LiCl media and subsequent grafting with bio-based polyols; (ii) solvent exchange and subsequent grafting with bio-based polyols. The influence of the two functionalization methods on the chemical and thermal properties of CNCs was examined. In both cases, the role of the two bio-based polyols on filler functionalization was elucidated. Afterwards, the functionalized CNCs were used at 5 wt% to produce bio-based composite polyurethane foams and their effect on the morphological, thermal and mechanical properties was examined. It was found that CNCs modified through freeze drying, solubilization and bio-polyols grafting exhibited remarkably higher thermal stability (i.e., degradation stages > 100 °C) with respect to the unmodified freeze dried-CNCs. In addition, the use of the two grafting bio-polyols influenced the functionalization process, corresponding to different amount of grafted-silane-polyol and leading to different chemico-physical characteristics of the obtained CNCs. This was translated to higher thermal stability as well as improved functional and mechanical performances of the produced bio-based composite PUR foams with respect of the unmodified CNCs-composite ones (the best case attained compressive strength values three times more). Solvent exchange route slightly improved the thermal stability of the obtained CNCs; however; the so-obtained CNCs could not be properly dispersed within the polyurethane matrix, due to filler aggregation.

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Section: Resultsmentioning

confidence: 99%

Effect of Different Methods to Synthesize Polyol-Grafted-Cellulose Nanocrystals as Inter-Active Filler in Bio-Based Polyurethane Foams

et al. 2023

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“…The large cell sizes exhibit poor tensile properties due to the stress concentration induced by their large size. Furthermore, the large cells act as cracks or defects during testing, resulting in tensile strength reductions [ 40 ]. However, in this study, the foams containing CCB exhibit a higher tensile modulus and tensile strength compared to the foam containing Fe 3 O 4 .…”

Section: Resultsmentioning

confidence: 99%

Electromagnetic Absorption and Mechanical Properties of Natural Rubber Composites Based on Conductive Carbon Black and Fe3O4

et al. 2022

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In contemporary civilization, the electromagnetic radiation from electronic devices and communication systems has become a substantial pollutant. High-performance electromagnetic absorbers have become a solution for absorbing unwanted electromagnetic waves. This research proposed a lightweight and flexible electromagnetic absorber produced from natural rubber filled with conductive carbon black (CCB) and Fe3O4. The effect of CCB, Fe3O4, and a combination of CCB and Fe3O4 as a hybrid filler on foam morpholog, electromagnetic reflectivity, tensile strength, and compression set properties were investigated. In addition, the effect of the alternating layered structure of CCB and Fe3O4 on electromagnetic absorption was investigated. The results indicated that the composite foam exhibited an interconnected network structure that enhanced the electromagnetic attenuation in the absorber. CCB increased the electromagnetic absorption of the foam, whereas Fe3O4 had less of an effect. The foam filled with the hybrid filler at the CCB/Fe3O4 ratio of 8/2 exhibited excellent electromagnetic absorption. The composite foam had a higher tensile modulus and higher strength compared to neat foam. The addition of CCB decreased the compression set; however, the compression set was improved by the incorporation of Fe3O4. Composite foams filled with hybrid filler can serve as highly efficient electromagnetic absorbing materials.

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“…[ 41,42 ] The existence of cell structure can also promote the impact strength. [ 9 ] The interaction of the two factors make the impact property of foamed PP increased by 55.7% from 15.60 to 24.29 MPa.…”

Section: Resultsmentioning

confidence: 99%

“…[ 7,8 ] Which gives microcellular foam PP great application potential in automobile, construction, aviation, industry, and agriculture. [ 9,10 ]…”

Section: Introductionmentioning

confidence: 99%

Preparation Process Orthogonal Optimization and Mechanical Properties of Microcellular Foam Polypropylene

Huang

Qin

et al. 2021

Macro Materials & Eng

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Melt strength, pressure and the amount of gas have significant effects on the foaming of polypropylene (PP). It is convenient to study the influence of these factors on foaming effect by orthogonal test. The experiment result shows that within the set factors and levels, the improvement of melt and the concentration of foaming masterbatch has the greatest influence on the cell size and density of foamed PP, respectively. When the concentration of azodicarbonamide (ADC) is 15 %, PP/ethylene‐propylene terpolymer (EPDM) = 90:10, and SiO2 content is 3%, the foaming effect is the best. At this time, the cell diameter decreases by 42.7%, cell density increases by more than 7.5 times compared with that without optimization. Material density decreases from 0.92 to 0.56 g cm−3. It is also found that good closed‐cell structure can improve the bending and impact properties of PP in varying degrees, especially the impact strength is 55.7% higher than that of neat PP. Finally, the promoting mechanism of cell structure on mechanical properties of materials is discussed, which is of great significance for the preparation of microfoamed PP materials and the deep research of its cell structure.

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Experimental-numerical studies of the effect of cell structure on the mechanical properties of polypropylene foams

Cited by 12 publications

References 26 publications

Effect of Different Methods to Synthesize Polyol-Grafted-Cellulose Nanocrystals as Inter-Active Filler in Bio-Based Polyurethane Foams

Effect of Different Methods to Synthesize Polyol-Grafted-Cellulose Nanocrystals as Inter-Active Filler in Bio-Based Polyurethane Foams

Electromagnetic Absorption and Mechanical Properties of Natural Rubber Composites Based on Conductive Carbon Black and Fe3O4

Preparation Process Orthogonal Optimization and Mechanical Properties of Microcellular Foam Polypropylene

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