Thermally expandable microspheres with excellent expansion characteristics at high temperature

Abstract

Thermally expandable core/shell particles with a poly(acrylonitrile-co-methacrylonitrile) shell and a hydrocarbon core (blowing agent) have been prepared by suspension polymerization. The objective of this study was to gain a deeper understanding of the parameters determining the expansion properties of these microspheres. It was found that the amount, the boiling point, and the structure of the blowing agent are important parameters for the expansion properties. For example, a higher maximum expansion was reached when using bulkier blowing agents and thus a lower diffusion rate through the polymer shell. Further, the amount and structure of the crosslinker were also found to be essential for the expansion properties. For this particular system, it was found that a dimethacrylate-functional crosslinker gave significantly better expansion when compared with diacrylate-or divinylether-based crosslinkers. Beside these parameters, it was also observed that the particle-size distribution influence the expansion properties of the microspheres. V C

Production of Valuable Lipophilic Compounds by Using Three Types of Interface Bioprocesses: Solid–Liquid Interface Bioreactor, Liquid–Liquid Interface Bioreactor, and Extractive Liquid-Surface Immobilization System

“…3 Liquid-liquid interface bioreactor L/L-IBR 3.1 Principle and characteristics of liquid-surface immobilization LSI systems Ballooned microspheres MS , used as fillers in composite materials such as paints and putty, have micro-scale diameters and very low density 70 . MS were used as key materials for generating fungal mats on the surface of an aqueous phase liquid medium .…”

“…Matsumoto Yushi-Seiyaku, Co., Ltd., Osaka produces different types of MS, including MFL-80GCA CaCO 3 -coated; mean diameter, 21 μm; density, 0.20 , MFL-80GTA talccoated; mean diameter, 21 μm; density, 0.20 , and MMF-DE-1 non-coated; mean diameter, 30 μm; density, 0.06 . MS are made of polyacrylonitrile; they are synthesized through polymerization of emulsions or suspensions, followed by thermal expansion 70 . A recently developed porous microparticle, Advancel HB-2051 polymethylmethacrylate; diameter, 20 μm; Sekisui Chemical Co., Ltd., Tokyo is currently being used in our laboratory.…”

Increased onset temperature of expansion in thermally expandable microspheres through combination of crosslinking agents

“…7 In the scientific literature, there are only a few studies regarding the synthesis and properties of TEMS. 6,[10][11][12][13][14][15] A PhD thesis by Huang 11 covers the synthesis of TEMS expanding at temperatures below and around 100 C, with an emphasis on particle formation and expansion properties. Kawaguchi and Oishi 15 investigated the influence of crosslinking of the polymer shell on the expansion properties and were able to correlate the expansion properties to the gel fraction and swelling ability of the polymer shell.…”

“…[2][3][4][5] When heated above the glass transition temperature (T g ) of the polymer shell, the particles expand as the hydrocarbon vapor pressure overcomes the yield strength of the polymer shell. 6 Vaporization of the hydrocarbon generates a tremendous volume increase, which is retained upon cooling because of plastic deformation of the polymer shell. As a result, the density of the microspheres can be reduced from about 1100 kg m À3 to $ 30 kg m…”

Effect of Grafting Degree of Maleic Anhydride on the Physical Properties of Expandable HDPE/KF

“…A foaming agent also needs to be adopted to decrease the weight of the polyolefin/KF composites. Thermal expandable microcapsule (EMC) is one of the best choices as a foaming agent for polyolefin/KF composites due to its easy process control compared to other chemical and mechanical foaming processes [7][8][9][10][11]. In general, the foaming behavior of KF, which is a polar polymer, is affected by the interface adhesion between the polyolefin and KF.…”