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The compression resistance and composite bonding of the polymer greatly increased because of the network structure formed by H-N…O-H…N intermolecular and O-H…N intramolecular hydrogen bond (Eq. 2).
The commercial PBI, which contains a typical structure of 2,2’-metaphenylene-5,5’-bisbenzimidazole, is produced by melt polycondensation of 3,3’,4,4’-tetra-aminobiphenyl (TAD) and diphenylisophthalate (DPIP) at 270-400℃ then solution spinning in DMAc or dry spinning[9].
For the hydroxy modified PBI, the PDBI fiber has the optimum heat resistance and is the optimal polymer structure.
Journal of Polymer Science: Part A: Polymer Chemistry, vol. 40(2002), p. 3703~3710
Journal of Polymer Science: Polymer Chemistry Edition, vol. 14(1976), p. 2807~2817.

Water Absorption Test Absorption behavior exposes paradoxical additive dynamics where material chemistry and microstructure interact counter-intuitively.
All mixes exhibited near-identical 28-day mass depletion (~170g from initial), confirming acid penetration bypasses additive chemistry except 15% bentonite (Mix04) which showed accelerated early dissolution (3761g/3d) yet paradoxically minimal strength loss.
This structure, made of calcium silicate-clay composites, is highly resistant to acid, effectively turning a damaging process into a strengthening one.
· Reserve the high-dosage combination of both materials exclusively for structures in highly corrosive environments.
International Journal of Concrete Structures and Materials, 17(1), 25. https://link.springer.com/article/10.1186/s40069-023-00585-5

The structure for the mullite coating is an amorphous one although that for the zirconia coating is a crystal one.
For mullite, melting, evaporation and decomposition of the structure are enhanced although for zirconia the raw structure remains.
In the coating structure, as shown in Fig. 5, a TiN, Ti2N and Ti mixed layer is observed with the 6-mm-diameter cathode.
Plasma Chemistry (ISPC), Praha, 1999, p. 1977
Plasma Chemistry (ISPC), Orleans, 2001, p. 2219

Though alternative initiation mechanisms for the generation of the active trivalent carbenium ions have been proposed [5], the carbonium initiation mechanism constitutes an attractive and plausible pathway that is seeing increased research interest from both experimental and computational chemistry.
Odd n-alkanes with nC � 11 have an orthorhombic crystalline structure and with such a mode of packing the nearest neighboring C-H bond (of adjacent molecules) to a primary radical site belongs to a chain-end methyl group, as can be seen in Fig. 3.
Alternatively, the presence of radical transformation in �irradiated odd n-alkanes with nC � 11 in CCl3F constitutes unambiguous evidence that the alkane nanoparticles do not pack according to the orthorhombic crystalline structure [11].
In view of general considerations on the crystallization of n-alkanes, it can be concluded that in such a case they are amorphous with no specific structure at all.
Valence bond resonance structures of penultimate C-H protonated n-alkanes.

However, due to its molecular structure, it exhibits poor mechanical properties.
Otherwise, the resin tends to form a three-dimensional network skeleton structure as its content increases.
This implies that overlapped filler particles lead to the formation of microvoids inside the composite structure, which produces a brittle structure of composites [19].
Caes, et al., Biomass to furanics: renewable routes to chemicals and fuels, ACS Sustainable Chemistry & Engineering. 3 (2015) 2591-2605
Klushin, et al., Technological aspects of fructose conversion to high-purity 5-hydroxymethylfurfural, a versatile platform chemical, Russian Journal of Organic Chemistry. 52 (2016) 767-771

Due to its complicated structure and its resistence to microbial attack, Lignin becomes the main pollutant in lignocellulose process industry [6].
With the abundant hydroxyl groups and other polar groups in its structure, chains of lignin may interact with each other by intramolecular and intermolecular hydrogen groups.
Effects of different kinds of acids for lignin's structure, Molecular weight, and glass transition temperature were discussed.
It could be concluded that the soft organic carboxylic acids have no effect on the structure of lignin.
Luo: Study on extraction of high purified lignin and its thermoplastic modification (Chemistry Industry Press, Beijing 2007)

The resulting material has dehydroxylated anhydrous structure but fibrous morphology remains unchanged.
Structure of the burned asbestos cement roofing is shown in Fig. 1 and 2.
An example of the structure prior and after burning the sample W2 is shown in Fig. 2.
Urso, Crystal chemistry of the high temperature product of transformation of cement-asbestos, J.
Taylor, Cement Chemistry, Academic Press (1990).

The structure and morphology of the modified attapulgite were characterized by infrared spectroscopy, scanning electron microscope (SEM).
Attapulgite(ATP), a natural nanomaterial with a formula [(Mg,Al)4Si8(O,OH,H2O)26.nH2O], is a rod-like crystalline hydrated magnesium aluminum silicate with unique three-dimensional structure，and its scheme structure was studied by Bradley early in 1940 [1].It has large specific surface area and moderate cation exchange capacity provided by its porous structure and absorbed cations separately.
Recent investigation has focused on the development of nanoscaled particles applied in analytical chemistry for its special physicochemical characteristics [6, 7].
The structure and morphology of the nanocomposites were observed using a Hitachi S-3000N scanning electron microscope.

Structural characterization showed that the nanocomposites were predominant in exfoliated structure.
Paiva et al. [8] reported that purpose and showed that the organophilization does not change the structure of this type of material.
These results can indicate that all nanocomposites exhibit exfoliated structure and / or partially exfoliated one.
These results corroborate with the results of X-ray diffraction, i.e., confirms exfoliated and / or partially exfoliated structures.
Domka: Journal of Physical and Chemistry of Solids Vol. 65 (2004), p. 441

The autogenous shrinkage deformation will increase and the following autogenous shrinkage crack will do harm to durability of concrete structure.
The pore structure constant can be determined by equal area projection method proposed in reference 5 or can be regressed from experiment result.
A bigger value of pore structure constant means much finer pore structure.
Furthermore, the autogenous crack in early-age concrete structure in real construction site can be a potential result of proposed model.
F.Tomosawa, Proceeding of 10th International Congress Chemistry Of Cement, 1997, Sweden [3].