Influence of crosslinking on the characteristics of thermally expandable microspheres expanding at high temperature

Jonsson, Magnus P.; Nordin, Ove; Kron, Anna Larsson; Malmström, Eva

doi:10.1002/app.32301

Cited by 25 publications

(18 citation statements)

References 98 publications

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“…Meanwhile, the irregular surface morphology of the TEMs from Group 14 could be recognized in Figure 6 (a), which might be caused by the cross-linking agent used for connecting the molecular chains of copolymers. 34,36 Figure 6(b) confirmed the core-shell structure of TEMs with an individual sample embedded in epoxy resin, taking from the TEMs shown in Figure 6(a). The diameter of this representative TEM was about 5 μm, and the internal diameter was nearly 3 μm, while the convex inner surface could be observed as well.…”

Section: Actual Expansion and Core-shell Structure Of Temssupporting

confidence: 57%

Preparation of small particle diameter thermally expandable microspheres under atmospheric pressure for potential utilization in wood

Zhang

et al. 2020

J of Applied Polymer Sci

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Small particle diameter thermally expandable microspheres (TEMs) were obtained for potential utilization in wood, with special attention on their particle diameters and expansion properties. The revolving speed of homogenization (RS) of 800~3000 r min −1 was applied in suspension polymerization under atmospheric pressure to prepare TEMs, with n-hexane as core material and the copolymer of acrylonitrile, methyl acrylate, and vinyl acetate as shell. (a) The effect of the RS on the particle diameters of TEMs presented a negative correlation at low RS and remained stable at high RS, (b) When the RS was 1900~2100 r min −1 , the optimized TEMs with average particle diameters of 3.82~4.06 μm were prepared, possessing expansion ratios of 3.4~4.3 and an expansion temperature of 112 C, (c)The optimized TEMs had core-shell structure and high encapsulated content of alkane, and (d) The TEMs with small particle diameters could be impregnated into wood and expand successfully in wood cell lumens.

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Section: Actual Expansion and Core-shell Structure Of Temssupporting

confidence: 57%

Preparation of small particle diameter thermally expandable microspheres under atmospheric pressure for potential utilization in wood

Zhang

et al. 2020

J of Applied Polymer Sci

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“…The applications of microcapsules include paper and board, printing ink, injection molding, extrusion, etc. [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 98%

“…When microcapsules are heated to 80-190°C, which is above the glass-transition temperature (T g ) of the polymeric shell, the shell softens and the liquid hydrocarbon evaporates, resulting in the expansion of the microcapsules [2,3]. The density of the microcapsules under these conditions decreases from 1100 to 30 kg/m 3 [4]. Upon heating, the volume of the microcapsules maintains to contain hydrocarbon prior to cooling, and the expansion is irreversible because of the plastic deformation of the shell [2].…”

Section: Introductionmentioning

confidence: 99%

Halloysite nanotubes as a stabilizer: fabrication of thermally expandable microcapsules via Pickering suspension polymerization

Kim

Jeoung

et al. 2015

Colloid Polym Sci

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Core-shell thermally expandable microcapsules were prepared via Pickering suspension polymerization. Acrylonitrile (AN) and methyl methacrylate (MMA) were used as the comonomers and the halloysite nanotubes (HNTs) were used as the Pickering emulsifier. The influence of the HNT concentration, AN/MMA ratio, and types of hydrocarbon was investigated. When the HNT concentration was 0.6 wt%, the microcapsules exhibited a core-shell morphology that contained approximately 35 wt% of the blowing agents with an average particle size of 232.0 μm. Increasing the MMA contents resulted in a larger particle size and lower thermal stability. Core-shell microcapsules could be synthesized using iso-hexane, iso-octane, and n-octane, but microcapsules could not be fabricated with n-pentane. At 1 and 3 bar, the contents of the encapsulated blowing agents were 10 %, whereas the contents of the encapsulated blowing agents were approximately 35 and 60 % at 1.5 and 2 bar, respectively.

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“…They also studied the influence of monomer chemical structure on heat resistance of thermally expandable microspheres [ 23 ]. Jonsson et al have studied the effects of blowing agent structure, content and crosslinking agent structure on expansion properties of poly (AN-co-methacrylonitrile) microspheres [ 24 , 25 , 26 ]. The structure and physical properties (i.e., the boiling point and vapor pressure) of the blowing agent had a significant influence on the expansion properties of the microspheres.…”

Section: Introductionmentioning

confidence: 99%

Expansion Properties and Diffusion of Blowing Agent for Vinylidene Chloride Copolymer Thermally Expandable Microspheres

2020

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Vinylidene chloride copolymer microspheres were synthesized by in situ suspension copolymerization of vinylidene chloride (VDC), methyl methacrylate (MMA), and/or acrylonitrile (AN) in the presence of a paraffin blowing agent. The effects of shell polymer properties including compositions, glass transition temperature (Tg), crosslinking degree, blowing agent type, and encapsulation ratio (Er) on the expansion properties of copolymer microspheres were investigated. Moreover, the diffusion properties of blowing agent in copolymer microspheres were studied. The results show that VDC-MMA-AN copolymer microspheres exhibited excellent expansion properties, and the volume expansion ratio (Ev) and the apparent density were decreased over 40 times, but it was difficult to expand for the VDC-MMA copolymer microspheres. In addition, the moderately crosslinked inside of the polymer shell enhanced the Ev more than 30 and the stable expansion temperature range (Tr) was about 30 °C by adding 0.2–0.4 wt% of divinyl benzene. The Tg of the shell polymer must be higher than the boiling point of the blowing agent as a prerequisite; the lower the boiling point of the blowing agent, the higher the internal gas pressure driven microsphere expansion, and the wider the Tr. By increasing the Er of blowing agent improved the Ev of the microspheres. The diffusion of pentane blowing agent in VDC-MMA-AN copolymer microspheres were divided into Fick diffusion and non-Fick diffusion.

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Influence of crosslinking on the characteristics of thermally expandable microspheres expanding at high temperature

Cited by 25 publications

References 98 publications

Preparation of small particle diameter thermally expandable microspheres under atmospheric pressure for potential utilization in wood

Preparation of small particle diameter thermally expandable microspheres under atmospheric pressure for potential utilization in wood

Halloysite nanotubes as a stabilizer: fabrication of thermally expandable microcapsules via Pickering suspension polymerization

Expansion Properties and Diffusion of Blowing Agent for Vinylidene Chloride Copolymer Thermally Expandable Microspheres

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