Effect of Resin and Blocked/Unblocked Hardener Mixture on the Production of Epoxy Foams with CO2 Blocked Hardener in Batch Foaming Process

The present study focuses on the processing and properties of epoxy foams by the use of CO2 blocked hardener N-aminoethylpiperazine (B-AEP) and different resins. Although some studies described the foaming with carbamates, little attention has been given to the interaction of resin properties (such as viscosity) on the foaming performance. Therefore, two resins, diglycidyl ether of bisphenol-A (DGEBA) and epoxy novolac (EN), as well as their 50:50 blend, were foamed with B-AEP and unblocked/blocked AEP hardener mixtures in a batch foaming process. Furthermore, the commercially available chemical blowing agent para-toluenesulfonyl hydrazide (TSH) was used as a benchmark for commonly used chemical blowing agents. The lowest density in this study was reached by the DGEBA+B-AEP system in the range of 215 kg/m3 with the drawback of an inhomogeneous cell structure and high cell size distribution. The best cell morphology and lowest cell size distribution was reached with the EN+15:85% unblocked:blocked hardener mixture, resulting in a density in the range of 394 kg/m3. A syntactic foam was achieved by a DGEBA+50:50% unblocked:blocked hardener mixture with a density of around 496 kg/m3. It was found that a higher viscosity of the resin lead to an increase in the density and a decrease in the cell size distribution range as a result of a closer expansion time window.

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

e-Polymers ◽

10.1515/epoly-2020-0060 ◽

2020 ◽

Vol 20 (1) ◽

pp. 713-723

Author(s):

Wei Gong ◽

Tuan-Hui Jiang ◽

Xiang-Bu Zeng ◽

Li He ◽

Chun Zhang

Keyword(s):

Mechanical Properties ◽

Size Distribution ◽

Cell Size ◽

Cell Structure ◽

Structure Parameters ◽

Cell Size Distribution ◽

Numerical Studies ◽

Polypropylene Foam ◽

The Impact ◽

The Relationship

AbstractThe effects of the cell size and distribution on the mechanical properties of polypropylene foam were simulated and analyzed by finite element modeling with ANSYS and supporting experiments. The results show that the reduced cell size and narrow size distribution have beneficial influences on both the tensile and impact strengths. Decreasing the cell size or narrowing the cell size distribution was more effective for increasing the impact strength than the tensile strength in the same case. The relationship between the mechanical properties and cell structure parameters has a good correlation with the theoretical model.

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Thermoplastic polyurethane foams: From autoclave batch foaming to bead foam extrusion

Journal of Cellular Plastics ◽

10.1177/0021955x20912201 ◽

2020 ◽

pp. 0021955X2091220

Author(s):

Amin Shabani ◽

Amir Fathi ◽

Sebastian Erlwein ◽

Volker Altstädt

Keyword(s):

Cell Size ◽

Thermoplastic Polyurethane ◽

Polyurethane Foams ◽

Morphological Properties ◽

Cell Size Distribution ◽

Foam Expansion ◽

Foam Extrusion ◽

Foaming Process ◽

First Time ◽

Batch Foaming

Two ester-based and one ether-based thermoplastic polyurethane grades have been used to produce thermoplastic polyurethane foams. The foaming process comprised pressure-induced batch foaming, foam extrusion, and bead foam extrusion by using an underwater granulator. Foam density and morphological properties, such as cell size, cell size distribution, and cell density, were measured through different analytical methods. Through autoclave batch foaming a minimum cell size of 10 µm and density of 202 kg/m3 is obtained, which is lower than the densities previously reported in the literature for thermoplastic polyurethane. Extrusion foaming however could not achieve the same range of foam expansion given that the lowest density achieved is 635 kg/m3 and a minimum cell size equal to 46 µm. The production of thermoplastic polyurethane bead foams is also reported for the first time. The minimum density of the obtained foamed beads is 306 kg/m3 and the lowest cell size is 55 µm.

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1465 - Cell size distribution of planktonic bacteria in shallow lakes

10.26226/morressier.5b5199c3b1b87b000ecf00ce ◽

2018 ◽

Author(s):

Zsuzsanna Márton ◽

Bianka Csitári ◽

Tamas Felfoldi ◽

Anna J Szekely ◽

Attila Szabo

Keyword(s):

Size Distribution ◽

Cell Size ◽

Shallow Lakes ◽

Cell Size Distribution ◽

Planktonic Bacteria

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The cell size distribution of tomato fruit can be changed by overexpression ofCDKA1

Plant Biotechnology Journal ◽

10.1111/pbi.12268 ◽

2014 ◽

Vol 13 (2) ◽

pp. 259-268 ◽

Cited By ~ 16

Author(s):

Anna Czerednik ◽

Marco Busscher ◽

Gerco C. Angenent ◽

Ruud A. de Maagd

Keyword(s):

Size Distribution ◽

Cell Size ◽

Tomato Fruit ◽

Cell Size Distribution

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Growth and Cell-Size Distribution of Marine Planktonic Algae in Batch and Dialysis Cultures

Journal of the Fisheries Research Board of Canada ◽

10.1139/f73-028 ◽

1973 ◽

Vol 30 (2) ◽

pp. 143-155 ◽

Cited By ~ 13

Author(s):

A. Prakash ◽

Liv Skoglund ◽

Britt Rystad ◽

Arne Jensen

Keyword(s):

Size Distribution ◽

Cell Size ◽

Growth Cycle ◽

Exponential Growth Phase ◽

Average Cell Size ◽

Cell Size Distribution ◽

Average Cell ◽

Planktonic Algae ◽

Maximum Cell ◽

Dialysis Culture

An extended exponential growth phase and a higher maximum population characterized growth of planktonic algae in a dialysis system compared with that in a batch system. Algal cells grown in a dialysis culture had higher chlorophyll content and a larger average cell size than those grown in a batch culture. In both types of culture, changes in cell-size distribution were related to the phases of the growth cycle with maximum cell-size during the stationary phase. Various interactions of the component reactions of photosynthesis leading to changes in growth pattern and cell-size distribution are discussed.

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