Synthesis and Compressive Response of Microcellular Foams Fabricated from Thermally Expandable Microspheres

Zhang, Ruizhi; Chen, Ju; Huang, Mao-Wei; Zhang, Jian; Luo, Guoqiang; Wang, Baozhen; Li, Meijuan; Shen, Qiang; Zhang, Lianmeng

doi:10.1007/s10118-019-2187-2

Cited by 13 publications

(12 citation statements)

References 27 publications

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“…This is because the solubility of CO 2 in the PHBV matrix decreases as the foaming temperature increases. 28 The number of nucleation sites decreases with the reduction of CO 2 concentration in the PHBV matrix. In 3 .…”

Section: Resultsmentioning

confidence: 97%

“…One key strategy is to construct cellular morphology in the polymer matrix. Over the past 10 years, supercritical carbon dioxide (scCO 2 ) has received considerable attention as a foaming agent for polymeric foams − owing to its nontoxicity and nonflammability. − It is well known that the foaming behavior of semicrystalline polymers is much more complicated than that of amorphous polymers on account of the existence of crystals . The existing crystal regions not only decrease the CO 2 solubility in the matrix but also influence cell nucleation and cell growth.…”

Section: Introductionmentioning

confidence: 99%

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Foaming of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with Supercritical Carbon Dioxide: Foaming Performance and Crystallization Behavior

Zhang

et al. 2020

ACS Omega

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Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) samples were successfully foamed using supercritical carbon dioxide as a physical foaming agent. PHBV sheets were first saturated at 175 °C followed by a foaming process at different temperatures (145 to 165 °C) and different CO2 pressures (10 to 29 MPa). It was found that microcellular structures with average cell sizes ranging from 6 to 22 μm and cell densities ranging from 108 to 1.2 × 109 cells/cm3 could be controllably prepared by selecting suitable foaming conditions. To investigate crystallization behavior during the foaming process and explore the corresponding foaming mechanism, differential scanning calorimetry, wide angle X-ray diffraction, and small-angle X-ray scattering characterizations were carried out. Stretching behavior during the cell growth stage may increase the crystal nucleation rate, and the generated crystal nucleus accelerates the crystallization rate as well as thickens PHBV crystal lamellae.

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Foaming of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with Supercritical Carbon Dioxide: Foaming Performance and Crystallization Behavior

Zhang

et al. 2020

ACS Omega

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“…Moreover, they have been used for making a variety of foaming materials as well. Generally, a foaming agent in plastic or rubber, not only reduces the product density, but also endows products with sound insulation or heat insulation [ 4 , 5 , 6 , 7 ]. When they were added to coating, printing ink, the three-dimensional effect was generated or the surface characteristics of products was strengthened [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

“…When they are applied in paper, paperboard, or non-woven fabric, the stereo effect of the products was formed and their anti-slip effect was enhanced [ 9 ]. Thermally expandable microspheres not only can be pre-foamed and then added to inks and coatings, but also can be mixed with plastics and rubber in the form of foaming in the process of processing [ 1 , 4 , 5 , 6 , 7 , 8 , 10 , 11 , 12 ]. Additionally, they were employed as a sacrificial template to fabricate macro-porous ceramic materials via a gel-casting process [ 13 ].…”

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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“…At a certain high temperature, the alkane inside the TEMs, as core material, could be gasified, thereby generating pressure to expand the softened copolymer shell, finally realizing an increase in the volume of the microspheres as several times larger than their initial state. Based on this unique property, TEMs gradually permeates a number of fields and products, such as adhesives, 1,2 foamed plastics, 3,4 three-dimensional coatings, 5 and even vehicle manufacturing industries. 6 Nevertheless, owing to the increasingly enhanced environmental awareness throughout the world, renewable and degradable biological materials receive much attention.…”

Section: Introductionmentioning

confidence: 99%

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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Synthesis and Compressive Response of Microcellular Foams Fabricated from Thermally Expandable Microspheres

Cited by 13 publications

References 27 publications

Foaming of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with Supercritical Carbon Dioxide: Foaming Performance and Crystallization Behavior

Foaming of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with Supercritical Carbon Dioxide: Foaming Performance and Crystallization Behavior

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

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

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