Study on Elimination of Surface-Exfoliation and Crack of ZrO2 Green Body of Gelcasting with Water-Solubility Macromolecule

2005 ◽  
Vol 475-479 ◽  
pp. 1317-1320
Author(s):  
Zhong Zhou Yi ◽  
Shi-en Wang ◽  
Yong Huang

Ceramic gelcasting has to be performed in nitrogen to avoid surface-exfoliation and crack of the green body. The rapid drying of gelled bodies can cause nonuniform shrinkage. Non-uniform drying in various regions due to the solvent gradient, induces structural and residual stresses which cause defects, such as cracking, warpage and the other malformations. These malformations can be minimized or eliminated via adding a proper amount of water-soluble polymer polyethylene glycol(PEG).This study concentrates attention on dispersion, rheological property and gelation behavior in the new system, The flexural strength and microstructure of ZrO2 green bodies were measured and observed.

2005 ◽  
Vol 475-479 ◽  
pp. 1309-1312
Author(s):  
Jing Tao Ma ◽  
Zhi Peng Xie ◽  
He Zhuo Miao ◽  
Bao Qing Zhang ◽  
Xu Ping Lin

A new ceramic gelcasting system was developed in this paper. The rheological behavior of alumina suspension with an addition of polymer was examined. Particular attention is given to the flexural strength of green body prepared from gelcasting in the presence of polymer.


Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1915 ◽  
Author(s):  
Eyob Wondu ◽  
Hyun Woo Oh ◽  
Jooheon Kim

In this study water-soluble polyurethane (WSPU) was synthesized from isophorone diisocyanate (IPDI), and polyethylene glycol (PEG), 2-bis(hydroxymethyl) propionic acid or dimethylolpropionic acid (DMPA), butane-1,4-diol (BD), and triethylamine (TEA) using an acetone process. The water solubility was investigated by solubilizing the polymer in water and measuring the contact angle and the results indicated that water solubility and contact angle tendency were increased as the molecular weight of the soft segment decreased, the amount of emulsifier was increased, and soft segment to hard segment ratio was lower. The contact angle of samples without emulsifier was greater than 87°, while that of with emulsifier was less than 67°, indicating a shift from highly hydrophobic to hydrophilic. The WSPU was also analyzed using Fourier transform infrared spectroscopy (FT-IR) to identify the absorption of functional groups and further checked by X-ray photoelectron spectroscopy (XPS). The molecular weight of WSPU was measured using size-exclusion chromatography (SEC). The structure of the WSPU was confirmed by nuclear magnetic resonance spectroscopy (NMR). The thermal properties of WSPU were analyzed using thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).


2016 ◽  
Vol 40 (5) ◽  
pp. 4513-4518 ◽  
Author(s):  
Guang Li ◽  
Farong Tao ◽  
Qian Liu ◽  
Liping Wang ◽  
Zhuang Wei ◽  
...  

A novel reversible colorimetric chemosensor based on polyethylene glycol has been developed to detect Cu2+ ions in pure aqueous solution.


1984 ◽  
Vol 42 ◽  
Author(s):  
N. B. Eden ◽  
J. E. Bailey

AbstractA model has been developed for the flexural strength of Portland cement pastes, based upon observed fracture behaviour of both normal and high strength pastes. Fibrillar or foil-like elements pull apart at a yield stress which is characteristic of the number of elements and interfacial shear strength. The former can be maximised by using a low water/cement ratio and the latter by inclusion of water-soluble polymer, followed by suitable drying. It is proposed that this is the mechanism by which high strength may be attained in Portland cement.


2014 ◽  
Vol 5 (19) ◽  
pp. 5775-5783 ◽  
Author(s):  
Lin Dai ◽  
Dan Li ◽  
Jing Cheng ◽  
Jing Liu ◽  
Li-Hong Deng ◽  
...  

Multiarm-polyethylene glycol–betulinic acid prodrugs were prepared by using multiarm-polyethylene glycol linkers and betulinic acid, which exhibited high drug loading capacity, good water solubility, and excellent anticancer activity.


1967 ◽  
Vol 39 (3) ◽  
pp. 166-182
Author(s):  
Aarne Mäkelä ◽  
Kaija Kotilainen

This paper deals with ash and mineral contents essential in the nutrition of livestock and man. The results of the investigated products are presented in Tables 1—3. Of the minerals the ash and the water-soluble part of it were determined, as well as the ash of the water-soluble fraction and the cations and anions P, Cl, K, Na, Ca and Mg. The determination of the water-solubility to some extent characterizes in what form the minerals occur in the plant. The following results were obtained in the determinations of the contents of total ash and the water-solubility. 1. As the Gramineae-grasses grow older the contents of ash and of individual minerals decrease, while the water-solubility simultaneously slightly declines (Table 1). The water-solubility of the ash and P is 70—80 %, that of K almost complete, that of Ca c. 50 % and that of Mg in general 60—70 %. 2. When red clover develops from the leaf stage to the blooming stage the contents of ash, N, P, Na, Ca and Mg decrease considerably, even to one half, while the content of K remains unchanged (Table 2). Simultaneously one can observe a decrease in the water-solubility. The water-solubility of the ash is 50—55 %, that of P 70—80 %, that of K almost complete, that of Ca 30—50 % and that of Mg 50—70 %. The contents of N, P and Ca in the leaves are considerably higher than in the stalks; at the blooming stage this is true also for Mg. On the other hand the content of K in the stalks is higher than in the leaves. The mineral content of the flowers is similar to that of the leaves, except that the content of ash is lower and that of phosphorus higher. 3. The water-solubility of the ash of cereal grains, cereal products and straws is 40—60 % (Table 2). The water-solubility of P in grains and wheat bran is c. 40 %, in brewers’ grains and straw 60—80 %. The water-solubility of K is only 60—80 %, except in straw where it is 90 %. The water-solubility of Ca in grains and brewers’ grains is c. 70 %, in the wheat bran and straw 30—40 %, in hulls of oats 20 % and awns of barley 66 %. The water-solubility of Mg in brewers’ grains is almost 70%, in oat grains and straw c. 50 %, in wheat grains and bran 20—30 %. 4. The water-solubility of the ash of roots and potato (Table 3) is high, 80—90 %. The ash content of tops and potato stalks is quite high, but the water-solubility of the ash only approximately 60 %. The water-solubility of P of the aforementioned plants and parts of plants is 70—90 % and that of K almost complete. The water-solubility of Ca in potato tubers, swede tops and spring rape is c. 50 %, where as it is low in other plants, especially in sugar beet tops and potato stalks. The water-solubility of Mg in potato tubers and tops is c. 70 %, whereas it is low in carrots, potato stalks and especially in swede roots. 5. In Table 3 are furthermore presented the mineral contents of some plants belonging to various groups of plants which to a limited extent may be used by some animals. The dandelion (Taraxacum officinale) is quite similar to the meadow fescue at the leaf stage with respect to its mineral content and the water-solubility of various minerals. The common sedge (Carex Goodenowii) is with respect to its mineral content and the water-solubility of the minerals similar to the blooming timothy, except; that the amount and water-solubility of P is low. The water-soluble ash and the contents and water-solubility of various minerals of water horsetail (Equisetum fluviatile) and common horsetail (E. arvense) are approximately the same as those of the meadow fescue at the leaf stage, except that the contents of Ca and Mg are higher and the water-solubility of Ca considerably less. The ash content of chickweed (Stellaria media) (c. 24 % in the dry matter) and of its specific minerals, the content of K (c. 10 %) is exceptionally high. On the other hand lichen (Cladonia alpestris) is especially poor in minerals.


Author(s):  
Galina V. Osipova ◽  
Nadezhda L. Pechnikova ◽  
Tatiana A. Ageeva

Different character of usage the porphyrins and their analogs immobilized on carrier polymers stimulates an increased interest in the synthesis and research of physico-chemical properties of porphyrin-polymer immobilizates. In this paper the peculiarities of a synthesis of water-soluble polymer systems containing cobalt disulfophthalocyaninate with the components of a different ratio are described. The methylolation reaction of polyacrylamide to immobilize cobalt disulfophthalocyaninate onto water-soluble carrier polymer has been carried out. It is known that heating polymethylolacrylamide or its solutions leads to the formation of three-dimensional structures with ether and methylene bridges. Therefore, initially the conditions for the preparation of polymethylolacrylamide with preservation of its water solubility were selected. It was found to obtain a water-soluble polymethylolacrylamide, it is necessary that the initial concentration of polyacrylamide in water did not exceed 2% by weight. The immobilization of phthalocyanine metal complex onto the modified polyacrylamide was carried out in two ways. The first is the interaction of the phthalocyanine metal complex with methylated polyacrylamide. The second is functionalization of polyacrylamide and the immobilization of phthalocyaninate metal complex onto the polymer in one-step. The introduction conditions of the cobalt disulfophthalocyaninate introduced influenced the formation of cross-linked structures in the synthesized samples. The introduction of macroheterocycle as a powder was found to promote the formation of insoluble compounds in aqueous media. Therefore, phthalocyanine metal complex was introduced into the system as 1% aqueous solution. The immobilization of the phthalocyanine metal complex onto a carrier polymer has been realized through the formation of hydrogen bonds between the methylol groups of polymethylolacrylamide and sulfo groups of the phthalocyanine metal complex and it was due to coordination interaction between the functional groups of the polymer and metallophthalocyanine as well. The amount of bound cobalt disulfophthalocyanine in the samples was determined by the electronic absorption spectra of the solutions of immobilized phthalocyanine metal complex onto the polymer. The mass content of immobilized cobalt disulfophthalocyaninate onto the polymer in the samples obtained by one-step is greater than in case of the samples obtained in two steps, the ratio of the initial reagents being the same.


2021 ◽  
Vol 78 ◽  
pp. 1-13
Author(s):  
A. Romanov ◽  
K. Ly ◽  
B. Kirchoff

Polyethylene glycol (PEG) is a non-carcinogenic, water-soluble polymer of ethylene oxide that has found wide applicability in industry and medicine, and has been used to embed and section small animal and plant tissues. Here we investigate the use of PEG for the rapid embedding of larger plant tissues. Ovaries of Musa velutina, Heliconia psittacorum and eight other species were embedded with a mixture of PEG 1450 and PEG 4000. It was found that tissues up to 6.5 × 10 mm could easily be embedded and sectioned in PEG. Embedded tissues could be stored at room temperature for up to 5 days with no detrimental effects. Sections were easily cut at 8–15 μm on a rotary microtome. PEG embedding resulted in equal or better tissue differentiation, better retention of cell inclusions, and reduced shrinkage compared with paraffin embedding. The process was also faster, requiring only 3–6 h compared with the 2 days needed for paraffin embedding. PEG is a rapid-embedding medium suitable for use with even large plant tissues.


Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2524
Author(s):  
Motahira Hashmi ◽  
Sana Ullah ◽  
Azeem Ullah ◽  
Muhammad Akmal ◽  
Yusuke Saito ◽  
...  

Cellulose is one of the most hydrophilic polymers with sufficient water holding capacity but it is unstable in aqueous conditions and it swells. Cellulose itself is not suitable for electrospun nanofibers’ formation due to high swelling, viscosity, and lower conductivity. Carboxymethyl cellulose (CMC) is also super hydrophilic polymer, however it has the same trend for nanofibers formation as that of cellulose. Due to the above-stated reasons, applications of CMC are quite limited in nanotechnology. In recent research, loading of CMC was optimized for electrospun tri-component polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and carboxymethyl cellulose (CMC) nanofibers aim at widening its area of applications. PVA is a water-soluble polymer with a wide range of applications in water filtration, biomedical, and environmental engineering, and with the advantage of easy process ability. However, it was observed that only PVA was not sufficient to produce PVA/CMC nanofibers via electrospinning. To increase spinnability of PVA/CMC nanofibers, PVP was selected as the best available option because of its higher conductivity and water solubility. Weight ratios of CMC and PVP were optimized to produce uniform nanofibers with continuous production as well. It was observed that at a weight ratio of PVP 12 and CMC 3 was at the highest possible loading to produce smooth nanofibers.


Author(s):  
Gurminder Singh ◽  
Jean-Michel Missiaen ◽  
Didier Bouvard ◽  
Jean-Marc Chaix

AbstractIn the present study, an additive manufacturing process of copper using extrusion 3D printing, solvent and thermal debinding, and sintering was explored. Extrusion 3D printing of metal injection moulding (MIM) feedstock was used to fabricate green body samples. The printing process was performed with optimized parameters to achieve high green density and low surface roughness. To remove water-soluble polymer, the green body was immersed in water for solvent debinding. The interconnected voids formed during solvent debinding were favorable for removing the backbone polymer from the brown body during thermal debinding. Thermal debinding was performed up to 500 °C, and ~ 6.5% total weight loss of the green sample was estimated. Finally, sintering of the thermally debinded samples was performed at 950, 1000, 1030, and 1050°C. The highest sintering temperature provided the highest relative density (94.5%) and isotropic shrinkage. Micro-computed tomography (μCT) examination was performed on green samples and sintered samples, and qualitative and quantitative analysis of the porosity confirmed the benefits of optimized printing conditions for the final microstructure. This work opens up the opportunity for 3D printing and sintering to produce pure copper components with complicated shapes and high density, utilizing raw MIM feedstock as the starting material.


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