Monomeric additives

The several kinetic rates are a consequence of Reactions 2-5 The first two represent monomeric additions the third describes all rates by which two polymeric molecules smaller than j form a molecule of size j. The molecule A AC contains a carboxylic anion the second molecule P. supplies aS oxirane and, in general, is any polymeric molecule of iSze j-n. 

Monomeric additions result in the first and second rate expressions. Polymeric molecules react with the activated intermediate at a rate that is proportional to their cumulative molar concentration P q. ... 

The cumulative molar concentration of polymeric species P 0 may be evaluated from the population density distribution, Equation 16. The first two rate expressions represent monomeric additions which do not change the molar concentration of polymeric molecules. A rate constant that describes functionality as a separable function of the molecule s degree of polymerization satisfies this constraint. The simplest, realistic function is the linear expression... 

Influence of Liquid Glass and Monomeric Additive Content on SPC Fluidity, Harshness, Workability, and Strength... 

It is apparent that the strength of SPC as a structural material depends on the ratio of binder to aggregate at conservation of technological plasticity of a mix. The influence of liquid glass and the monomeric additive content on fluidity and harshness of SPC mixes was investigated. Results of the experiments are presented in Table 3.1. 

Influence of the monomeric additive (TFS) on the technological properties of SPC was investigated with plastic mix (content of liquid glass is 11%). Experimental results are illustrated in Table 3.2. 

Results of the research show that introduction of TFS increases the harshness of SPC mixes. Regarding the workability of the investigated compositions, the SPC mix can be classified as plastic with content of liquid glass of 11% and monomeric additive of 3%. The influence of the quantity of liquid glass on SPC strength was defined both for compositions with the monomeric additive and without it. 

SPC mix with monomeric additives is characterized by an exponential increase in shrinkage deformations. Formation of the SPC structure is accompanied by intensive compression of liquid glass gel by capillary forces of intermicel-lar liquid. The compression of the gel causes maximum shrinkage deformation from the very beginning of hardening. Introduction of FA or TFS considerably reduces the influence of capillary forces due to a decrease of liquid tension into capillaries [3,4],... 

It is known that an elevated permeability of usual SPC based on liquid glass is intimately connected with the big porosity and filtering defects. Because of this, application of commonly used SPC requires a leak proof and chemically stable lining of expensive materials (lead, polyisobutylene, etc.). Filtration and diffusive permeability of SPC with monomeric additives (TFS, FA) in aggressive environments were studied. 

Data show that all SPC samples with monomeric additives withstand the pressure of water at 0.6 MPa, whereas samples without the additive (composition 1) began leaking after 1-1.5 hours of testing at an overflow pressure of 0.1 MPa. Thus, it is obvious that the additives TFS and FA eliminate filtering defects in the form of microcracks and conducting channels on a border gel filler. ... 

Influence of Monomeric Additives on Chemical Resistance of SPC Compositions... 

Highly diffusive penetration of SPC can be drastically lowered by active additives that are capable of raising SPC density, and, therefore, its corrosion resistance. As indicated previously, the most effective results were obtained by introduction of FA or TFS additives. Addition of monomeric additives to silicate composition improves the physical-mechanical characteristics and chemical resistance of silicate compositions due to improvement in the quality of silicate bonds and better adhesion between the binder and coarse filler [1], In other words, the influence of the monomeric additives is conditioned by consolidation of liquid glass gel during hardening and modifications of alkaline components due to inoculation of furan radicals. 

Results concerning the influence of the kind of monomeric additive on SPC corrosion stability is shown in Table 3.10. 

As shown in [1, 2], monomeric additives are favorable for increasing the crack resistance characteristics of SPC due to... 

Optimal composition of SPC includes 11.23% liquid glass and 0.34% monomeric additives (FA or TFS). 

Introduction of monomeric additives leads to significant reduction of shrinkage. Use of 3% TFS (from weight of liquid glass) reduces shrinkable deformations up to 0.06%. 

SPC samples with monomeric additives withstand the pressure of water to 0.6 MPa. The additives TFS and FA liquidate the filtering defects in the form of microcracks and conducting channels on a border gel filler. 

Chemical characteristics. Both resins will react with formaldehyde to initiate and form monomeric addition products. Six molecules of formaldehyde added to one single molecule of melamine will form hexamethylol melamine, whereas a single molecule of urea will combine with two molecules of formaldehyde to form dimethylolurea. If carried on further, these condensation reactions produce an infusible polymer network. The urea/formaldehyde and melamine/formalde-hyde reactions are illustrated in Fig. 2.2. 

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