Polyvinyl Alcohol Levels Research Articles

Effects of Polymer Loading on Tropical Wood Polymer Composite (WPC)

Batai (paraserianthes moluccana) tropical wood species was impregnated with three levels of polyvinyl alcohol (PVA) solutions (25%, 50% and 75%) for composite manufacturing. Manufactured wood polymer composites (WPCs) were characterized using Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), free-free vibration testing, and the dimensional stability analysis. The dynamic Young’s modulus (Ed) was calculated using the free-free flexural vibration method. Impregnation of PVA solutions into wood samples was confirmed through FTIR and SEM. WPC from 75% PVA solution showed lower water absorption and improved dimensional stability. The fabricated WPC yielded a higher Young’s modulus compared with the raw one.

Study of Dynamic Young's Modulus and Dimensional Stability of Polyvinyl Alcohol Modified Batai Tropical Wood

Batai tropical wood (paraserianthes moluccana) was impregnated with three levels of poly vinyl alcohol (PVA) solutions (25%, 50% and 75%) and the dynamic Young’s modulus, water absorption and dimensional stability of the manufactured wood polymer composites (WPC) were assessed. The modified wood polymer composites (WPC) were characterized by microstructural analysis (Fourier transform infrared spectroscopy and scanning electron microscopy) and free-free vibration testing. The dynamic Young’s modulus (Ed) was calculated using the free-free flexural vibration method. Fourier transform infrared spectroscopy indicated the absorption bands of raw wood to be 1627 cm-1 due to carbonyl stretching and WPC show increased absorption band near 1733 cm-1. WPC of 75% PVA solution exhibited improved dimensional stability and lower water absorption. The manufactured WPC yielded a higher Young’s modulus compared with the raw one. Keywords: Wood polymer composite; Tropical wood; Non-destructive testing. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i2.2729 J. Sci. Res. 2 (2), 227-236 (2010)

Response surface optimization of the feed compositions of biodegradable packaging foams

AbstractResponse surface methodology (RSM) was used to analyse the effects of polyvinyl alcohol (PVOH) and calcium carbonate (CaCO3) on the physical and mechanical properties (radial expansion ratio, bulk density, compressibility and spring index) of a biodegradable cushioning extrudate. A rotatable central‐composite design (CCD) was used to develop models for the objective responses. The experiments were run at 125°C with a feed rate of 27.8 l/h, screw speed of 215 r.p.m. and die diameter of 3.92 mm. Responses were most affected by changes in PVOH levels and to a lesser extent by CaCO3 levels. Individual contour plots of the different responses were overlaid. An optimum radial expansion ratio of 3.39, bulk density of 0.065 (g/cm3), compressibility of 32.27(N), and spring index of 0.906 were identified at 36% PVOH and 5% CaCO3. Copyright © 2005 John Wiley & Sons, Ltd.

Development of bovine embryos in chemically defined medium at different levels of polyvinyl alcohol

This work was undertaken in order to study the developmental competence of nuclear transfer feline embryos with regard to the recipient-cytoplast’s age and type of somatic cells used as donor nuclei.Oocytes were recovered by mincing the ovaries in HEPES-buffered TCM-199. Selected cumulus–oocyte complexes (COCs) with compact cumulus cell mass and a dark, homogenous ooplasm were cultured for maturation in the modified medium TC-199 for 24, 35, and 43 h, and after enucleation were used as a source of recipient cytoplasts for exogenous somatic nuclei.Two experiments were carried out. In Experiment 1, the source of recipient cytoplasts was oocytes matured in vitro for 24 h (Group 1), 35 h (Group 2), and 43 h (Group 3), while the source of donor nuclei was cycling fetal fibroblasts. Somatic cell–cytoplast complexes (SC–CCs) were fused electrically by double DC pulses of 2.0 kV/cm for 15 μs. The reconstructed embryos were cultured in B2 medium for 72 h after NT, then co-cultured with BRL cells in the same medium supplemented with 10% FBS at 38.5 °C under 5% CO2 in air. In Groups 1, 2, and 3, the fusion rates were 71.4 (25/35), 74.6 (47/63), and 57.5% (46/80), respectively. The cleavage rates in Groups 1, 2, and 3 were 80.0 (20/25), 55.3 (26/47), and 60.8% (28/46), respectively. The development to morula and blastocyst stages was higher in Groups 1 and 2 compared to Group 3 (morula stage 14/25 (56.0%), 16/47 (34.0%), and 13/46 (28.2%); blastocyst stage 2/20 (8.0%), 4/47, (8.5%), and 0/46, respectively). In Experiment 2, the oocytes matured for 24–35 h were used as a source of recipient cytoplasts and cycling fetal fibroblasts and cumulus cells derived from mature COCs were used as a source of donor nuclei. The fusion rates were 115/193 (59.6%) versus 65/143 (45.4%) for fetal fibroblasts and cumulus cells, respectively. The cleavage rate was 72/115 (62.6%) versus 48/65 (73.8%), and the development to blastocyst stage 6/115 (5.2%) versus 5/65 (7.7%), for fetal fibroblast and cumulus cells, respectively. In conclusion, a prolonged maturation period of cat oocytes decreases developmental competence of reconstructed embryos, especially the ability to reach the blastocyst stage. The in vitro development of reconstructed embryos with either nuclei of fetal fibroblasts or cumulus cells was at approximately the same level.

Soil stabilization by polyvinyl alcohol and its effects on the growth of wheat

A factorial experiment was carried out in the glasshouse using six levels of polyvinyl alcohol (PVA) and five levels of nitrogen fertilizer. Each pot contained 3 kg of the Urrbrae fine sandy loam taken from an area of low fertility. When no PVA was added, only 35% of the wheat seeds emerged, while at the lowest application rate of PVA (0.05% W/W for 0-2 cm layer of soil) the emergence rate was 90%. PVA did not affect plant growth or the uptake of nitrogen. Contrary to previous experience, the acceptance of simulated rain was not increased with the application of PVA, but soil losses were not significantly reduced.