The effect of interlayer cations on the expansion of vermiculite

Huo, Xiaoxu; Wu, Limei; Liao, Libing; Xia, Zhiguo; Wang, Lijuan

doi:10.1016/j.powtec.2012.02.059

Cited by 61 publications

(35 citation statements)

References 22 publications

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“…Macromolecules with random coil conformations are difficult to get through the narrow interlayer, but macromolecules are able to smoothly enter into the interlayer of EVMT because the interlayer space of EVMT is much larger than that of natural, unexpanded VMT. [13][14][15] As a result of the ball-milling shear effect, the PVOH macromolecules entered into the interlayer space of EVMT, separated the platelets, and increased the d 001 of EVMT; this resulted in the shift of the (001) characteristic diffraction peaks to small angles in the XRD spectra. 12 Figure 1 and Table I show that the Yuli EVMT exhibited characteristic diffraction peaks at 2hs of 6.09, 17.77, and 29.888; these belonged to the respective crystal planes (001), (003), and (005) of EVMT.…”

Section: Pvoh Intercalation Into Evmtmentioning

confidence: 99%

Influence of nanovermiculites with a high aspect ratio and stretch orientation on the microstructure of polypropylene films

et al. 2015

J of Applied Polymer Sci

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In this article, we present a process for preparing organovermiculites, which consist of expanded vermiculite (EVMT)poly(vinyl alcohol) (PVOH) created by the mechanical ball-milling of EVMT in a PVOH-water solution. We then discusses the influence of EVMT-PVOH on the barrier performance, crystallization behavior, thermal stability, and mechanical properties of modified blown polypropylene (PP) films. EVMT was intercalated and exfoliated by PVOH macromolecules to obtain a kind of hybrid EVMT-PVOH. PVOH served as both an intercalating agent into EVMT and a compatibilizer between EVMT and PP. Compared with the original (unmodified) PP, when the EVMT loading ranged from 0.1 to 2.0%, although the crystallinity decreased for most PP films, the thermal stability and mechanical properties all improved. Moreover, EVMT platelike particles with a high aspect ratio (ca. 550) dispersed in the PP matrix also improved the barrier properties of the modified PP films, which was in accordance with the Nielsen model. EXPERIMENTAL MaterialsThe VMT used in this experiment was EVMT from the Yuli (Weili) Co. Qeganbulak VMT deposit in Xinjiang, China. The EVMT was obtained by the treatment of the natural VMT by quickly going through the channel-type furnace at 11008C. PVOH resin with Elvanol grade 90-50 was purchased from DuPont (Pudong New District, Shanghai, China). PP was purchased from MaoMing SINOPEC (MaoMing, China) with grade F280 (PPH-F-022-A); it was a special PP homopolymer for PP with a melt flow index of 2.8 g/10 min and an isotacticity of 96.5%. Preparation of EVMT-PVOHA certain mass of PVOH was added to water that was heated gently until the PVOH dissolved. The EVMT was crushed in a high-speed pulverizer for 5 min, sieved to get 50-100-mesh EVMT, and mixed with the prepared PVOH-water solution. The mixture was ball-milled at a speed of 2000 rpm in a highspeed ball miller (GJ-28, Qingdao Haitong Special Instrument Co., Ltd., Qingdao City, China) for 30 min. Then, EVMT-PVOH slurry was dried in an oven at 708C for 24 h in a vacuum. The final pellet-form EVMT-PVOH (5:95 wt %) was obtained by cutting and was characterized with XRD. Preparation of the EVMT-PVOH-PP Nanocomposite BlendsThe EVMT-PVOH-PP polymer-matrix composites (nanocomposites) were prepared in a screw extruder [CTE-35, Coperion Keya (Nanjing) Machinery Co., Ltd., China] at 300 rpm. The melt-blending temperature profiles selected were 185, 200, 215, and 2308C. The weight ratios (weight percentage) of EVMT-PVOH to PP were fixed at 0.1, 0.3, 0.5, 1.0, 1.5, and 2.0. The EVMT-PVOH-PP nanocomposites were pelletized and dried at 608C for 3 h. The weight ratios of PP to EVMT to PVOH in the polymer-matrix composite samples 1-7 were 100:0:0, 99.8:0.1:0.1, 99.4:0.3:0.3, 99.0:0.5:0.5, 98.0:1.0:1.0, 97.0:1.5:1.5, and 96.0:2.0:2.0, respectively.

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Section: Pvoh Intercalation Into Evmtmentioning

confidence: 99%

Influence of nanovermiculites with a high aspect ratio and stretch orientation on the microstructure of polypropylene films

et al. 2015

J of Applied Polymer Sci

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“…The degree of expansion depends on the flake size, the nature of interlayer cations, the presence or absence of interstratified phases, the heating rate and the terminal temperature (Huo et al, 2012;Justo et al, 1993;Marcos et al, 2009;Muiambo et al, 2010). For some 4 applications, e.g.…”

Section: Introductionmentioning

confidence: 99%

Characterization of urea-modified Palabora vermiculite

Muiambo

Focke

Atanasova

et al. 2015

Applied Clay Science

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Replacing the exchangeable interlayer ions in Palabora vermiculite with magnesium, aluminium or iron(III) ions does not affect the exfoliation onset temperature (456  11 C).However, co-intercalation of minor amounts of urea lowers the exfoliation onset temperature to 209  35 C. This significant decrease is attributed to the low thermal stability of urea which releases ammonia and water as blowing agents. Thermo-mechanical analysis indicates that the expanded vermiculite exhibits spring-like properties. Part of the original expansion is recovered when the applied force is removed. The observed hysteresis is attributed to the progressive flattening of warped/buckled sheets that make up the expanded worm-like structure. Provided the expanded flake has not been heated beyond 450 C, it can be reconstituted by applying a sufficiently high compressive force followed by equilibration with distilled water. Such flakes show the conventional exfoliation behaviour when heated again.

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“…The mass losses of EVrm occurred at 30-210°C are attributed to the removal of surface-adsorbed water and interlayer water associated with interlayer cations, respectively. The mass loss of dehydroxylation occurred at 600-810°C, and the mass losses at 810-920°C correspond to phase transformation (He et al, 2003;Perez-Maqueda et al, 2003;Huo et al, 2012). For neat HDTMAB, the mass loss at about 266°C, corresponds to its decomposition (Fig.…”

Section: Thermal Stability Of Hevrmmentioning

confidence: 94%

Structure and thermal stability of organo-vermiculite

Wei

2016

Applied Clay Science

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The effect of interlayer cations on the expansion of vermiculite

Cited by 61 publications

References 22 publications

Influence of nanovermiculites with a high aspect ratio and stretch orientation on the microstructure of polypropylene films

Influence of nanovermiculites with a high aspect ratio and stretch orientation on the microstructure of polypropylene films

Characterization of urea-modified Palabora vermiculite

Structure and thermal stability of organo-vermiculite

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