Unique pore structure formed in montmorillonite in the presence of polyvinyl alcohol and aluminium chlorohydroxide

ABSTRACTMDF(Macro-Defect-Free ) cement pastes, which consist of portland cement and polyvinyl alcohol/acetate, were prepared by varying the temperature during pressing and drying operations. We then examined the expansion of MDF cement pastes at various constant humidities. There was a large difference in expansion above 60%R.H. between samples prepared varying temperature at which samples were pressed. Samples pressed at 90 °C showed less expansion than samples pressed at 40 °C.The pore structure of MDF cement pastes before exposure to moisture was measured by nitrogen adsorption, mercury intrusion porosimetry and image analysis. The properties of a matrix containing polyvinyl alcohol/acetate and cemnt hydrates were also investigated by TEM, IR and XPS.There were not large differences in the result of IR and XPS measurement between the MDF cement pastes prepared at various temperatures. Calcium hydroxide crystal, lying perpendicular to cement particles, were often observed only in the MDF cement pastes pressed at 90 °C which occurs by water absorption, seems to be suppressed by calcium hydroxide crystal.

Download Full-text

Cytotoxicity Evaluation of Bioactive Glass-Polyvinyl Alcohol Hybrid Foams Prepared by the Sol-Gel Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.284-286.589 ◽

2005 ◽

Vol 284-286 ◽

pp. 589-592 ◽

Cited By ~ 4

Author(s):

Marivalda Pereira ◽

Najat Al-Saffar ◽

Jamuna Selvakumaran ◽

Larry L. Hench

Keyword(s):

Tissue Engineering ◽

Polyvinyl Alcohol ◽

Cell Viability ◽

Bioactive Glass ◽

Pore Structure ◽

Sol Gel ◽

Cleaning Procedure ◽

Gel Method ◽

Cleaning Methods ◽

Hybrid Foams

Hybrid bioactive glass-polyvinyl alcohol foams for use as scaffolds in tissue engineering were developed through the sol-gel route. Hybrids produced by this route present a high acidic character due to the catalysts added during processing and may also contain residual organics after the drying step. Therefore, an additional cleaning step is necessary to produce biocompatible materials. In this study hybrid PVA/bioactive glass foams were cleaned using various procedures and cytotoxicity evaluation was conducted. All the cleaning methods used increased the cell viability levels compared to samples not subjected to a cleaning procedure. The most effective cleaning procedure used was the immersion in NH4OH solution. The cleaning procedure changed the composition and pore structure of the final material.

Download Full-text

Study on Mechanical Properties and Pore Structure of Hybrid Fiber Reinforced Rubber Concrete

Crystals ◽

10.3390/cryst11111307 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1307

Author(s):

Yushan Liu ◽

Jianyong Pang ◽

Qiaoqiao Chen ◽

Weijing Yao

Keyword(s):

Mechanical Properties ◽

Polyvinyl Alcohol ◽

Pore Structure ◽

Volume Fraction ◽

Basalt Fiber ◽

Hybrid Fiber ◽

Hybrid Fibers ◽

Polyvinyl Alcohol Fiber ◽

Rubber Particles ◽

Rubber Concrete

In this work, to reduce the probability of brittle failure in the support structure of deeply buried high-stress soft rock roadways, hybrid-fiber reinforced rubber concrete (HFRRC) was investigated using the orthogonal test, and the effects of various factors on the performance were studied. The mechanical properties, pore structure, and microstructure of rubber concrete reinforced by basalt fiber (BF) and polyvinyl alcohol fiber (PF) were studied from macroscale, mesoscale, and microscale perspectives. The results revealed that the content of the rubber particles has a significant impact on strength. Further, the addition of the hybrid fibers to the concrete was found to have a positive effect on the splitting tensile strength and the flexural strength. However, no significant effect was observed on the compressive strength. Furthermore, it was found that the content of BF and PF have a significant impact on the energy dissipation capacity and ductility, and the influence of the PF content is greater than that of the BF content. The concrete with 10% rubber particles of 1–3 mm, a volume fraction 0.3% basalt fiber, and a volume fraction 0.2% polyvinyl alcohol fiber was obtained as the optimal mix proportions. Moreover, it was found that the random distribution of the rubber particles and the hybrid fibers optimized the pore structure, inhibited the expansion of the cracks, and reduced the brittleness of the concrete. The findings of this study can provide a useful reference for the application of an environmentally friendly material with recycled rubber aggregate and hybrid fiber.

Download Full-text

The effect of polyvinyl alcohol on the nitrogen surface area and pore structure of soils

Soil Research ◽

10.1071/sr9670077 ◽

1967 ◽

Vol 5 (1) ◽

pp. 77 ◽

Cited By ~ 21

Author(s):

BG Williams ◽

DJ Greenland ◽

JP Quirk

Keyword(s):

Polyvinyl Alcohol ◽

Specific Surface ◽

Pore Structure ◽

Pore Size Distribution ◽

Pore Size ◽

Surface Area ◽

Specific Surface Area ◽

Clay Soil ◽

Adsorption Data ◽

Desorption Isotherms

Changes in the specific surface area and pore size distribution due to adsorption of polyvinyl alcohol (PVA) by aggregates of a clay soil have been determined from the desorption isotherms for nitrogen at -195�C. The specific surface area was reduced. The volume of pores less than 30 A wide decreased by an amount considerably in excess of the volume of PVA adsorbed. These results are interpreted in terms of 'peripheral pore occupation' by the polymer, preventing access of nitrogen molecules to pores and surfaces within domains. Adsorption data previously obtained also indicated limited penetration of domains by the polymer.

Download Full-text

Superhydrophilic polyvinyl alcohol-formaldehyde composite sponges with hierachical pore structure for oil/water emulsion separation

Reactive and Functional Polymers ◽

10.1016/j.reactfunctpolym.2021.104975 ◽

2021 ◽

pp. 104975

Author(s):

Di Sha ◽

Run Zheng ◽

Baolong Wang ◽

Jiuduo Xu ◽

Kai Shi ◽

...

Keyword(s):

Polyvinyl Alcohol ◽

Pore Structure ◽

Water Emulsion ◽

Emulsion Separation ◽

Oil Water

Download Full-text

Correlation of Pore Structure and Permeability by SEM-Image Analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180896 ◽

1990 ◽

Vol 48 (1) ◽

pp. 428-429

Author(s):

C. A. Callender ◽

Wm. C. Dawson ◽

J. J. Funk

Keyword(s):

Image Analysis ◽

Pore Structure ◽

Imaging System ◽

Pore Space ◽

Simulation Models ◽

Image Analyzer ◽

Imaging Data ◽

Sem Images ◽

Thin Sections ◽

Rock Types

The geometric structure of pore space in some carbonate rocks can be correlated with petrophysical measurements by quantitatively analyzing binaries generated from SEM images. Reservoirs with similar porosities can have markedly different permeabilities. Image analysis identifies which characteristics of a rock are responsible for the permeability differences. Imaging data can explain unusual fluid flow patterns which, in turn, can improve production simulation models.Analytical SchemeOur sample suite consists of 30 Middle East carbonates having porosities ranging from 21 to 28% and permeabilities from 92 to 2153 md. Engineering tests reveal the lack of a consistent (predictable) relationship between porosity and permeability (Fig. 1). Finely polished thin sections were studied petrographically to determine rock texture. The studied thin sections represent four petrographically distinct carbonate rock types ranging from compacted, poorly-sorted, dolomitized, intraclastic grainstones to well-sorted, foraminiferal,ooid, peloidal grainstones. The samples were analyzed for pore structure by a Tracor Northern 5500 IPP 5B/80 image analyzer and a 80386 microprocessor-based imaging system. Between 30 and 50 SEM-generated backscattered electron images (frames) were collected per thin section. Binaries were created from the gray level that represents the pore space. Calculated values were averaged and the data analyzed to determine which geological pore structure characteristics actually affect permeability.

Download Full-text