Resin network

J. C. Hedrick, N. M. Patel, and J. E. McGrath, Toughening of Epoxy Resin Networks with Functionalized Engineering Thermoplastics, in Rubber Toughened Plastics, K. Riew (Ed.), American Chemical Society, Washington, DC, 1993. 

The control resin network used in this study was a diglycidyl ether-based epoxy resin crosslinked with a cycloaliphatic diamine. Cooligomeric modifiers were prepared having varying percentages of TFP and DP siloxane and aminoethylpiperazine end groups. Both siloxane and ATBN and CTBN elastomers were used as epoxy modifiers, the latter two having been included to facilitate direct comparisons between modifiers in similarly prepared networks. 

Keywords silicone resin network, masonry protection, building material, natural stone impregnation, silicone coating of mineral substrates, structure-effect principle of trifunctional silicones... 

Long-term stability under exposed conditions, implying a permanent anchoring of the hard silicone resin network (organo-modified quartz structure) to the substrate. 

There is reason to believe that the molecular structure of crosslinked trifunctional silanes/siloxanes may also influence the durability of the resulting silicone resin network [14, 40 - 42]. Allowance must be made here for the fact that such considerations are models in nature and also that we still do not have adequate knowledge of the molecular principles of fully condensed silicone resin networks [15]. 

Mechanisms of Silicone Resin Network Attachment to a Mineral Substrate... 

The Silicone Resin Network in Paints and Impregnated Building Materials... 

The Silicone Resin Network and the Polymer Binder in the Paint Microstructure... 

Exposed filler surfaces are always coated by a nanoscale silicone resin network, although this is only apparent at much higher magnification, as can be seen from the detail (white arrow) in Fig. 3b. 

The silicone resin network (polymethylsilicic acid) coats the surfaces of both large calcite grains and small titanium dioxide particles with an ultra-thin veil-like film. Clear evidence of an existing network coating is the apparent rounding and void filling just a few nanometers thick (Figs. 3b,d) between the mineral phases (white arrows). 

Strength of the Silicone Resin Network in the High-Porosity Coating Microstructure... 

The Silicone Resin Network in Building Material Microstructure and Building Stone... 

Fig. 6. Comparative SE images of an untreated Lower Triassic red sandstone and a red sandstone (both Wfistenzeller Buntsandstein) impregnated with a silicone microemulsion concentrate (SMK). a, b Untreated Mica layer surfaces (white arrows) and clay mineral fibers (illite, black arrow) without signs of polymeric encapsulation, c - f Impregnated with SMK d A detailed view fiom Fig. 6c clay mineral-mica intergrowlfas reveal structured silicone films on the prism plane of the cl mineral, e Clay mineral intergrowth with quartz, coated with a veil of silicone resin (white arrow) plan view of crystallogra]diic prism plane (110) or (010) (black arrow) plan view of sheet plane (001). f Detailed view from Fig. 6e day mineral perfectly encapsulated by structured silicone resin network.

Model Ideas about the Silicone Resin Network and Substrate Attachment... 

Finally, the question arises as to the molecular structure of the polymeric, nanoscale silicone resin network, with one partial aspect still largely unknown, namely a possible connection between molecular stmcture and durability in practice [14, 15,40,41]. 

Furthermore, little is known about the molecular basics of the fully condensed network [15, 65]. Whether modem spectroscopic analytical techniques, such as DRIFT and XPS combined with TOF-SIMS [15, 42, 65], reproduce the molecular stmcture of the polycondensed silicone resin network with enough accuracy will be revealed by future studies [65]. 

Opinions as to how a silicone resin network is attached to mineral surfaces (mostly quartz), all gleaned from this study and from the literature [19, 20, 22, 66, 68, 69], may be summarized as follows. 

Molecular modeling was used in an attempt to answer the questions of structure and bonding of the silicone resin network that are associated with the three viewpoints above. In other words, this method was used to investigate the relationship between the molecular architecture of the silicone resin and the ability to bond or to attach to mineral surfaces. To compare those abilities on a molecular level is not trivial, since the steric properties of such resins can only be described sufficiently in statistical terms. 

Fig. 13. Modeling of a water-repellent silicone resin network on quartz (arbitrary assembly), viewed from the front (a) and from the side (b). Hie three-dimensional network is built up of two-dimensional monolayers (methyl derivative) for optical reasons (this leads to seemingly unsaturated oxygen atoms, which form the oxygen bridges in the three-dimensional case). A simplified silicone resin network on quartz could be composed of covalently bound polysiloxane chains, incompletely crosslinked polysiloxane, and embedded silsesquioxanes or homosilsesquioxanes (cages and ladders), going from the bottom (quartz) to the top [28, 42, 75, 78, 79]. The network has been optimized from graphical aspects. Total height approx. SO A.

Building materials exposed to weathering are corroded by the action of atmospheric influences, especially water destruction is unavoidable in the long term. Water-repellent treatments can certainly not totally stop these harmful processes, but, given adequate envelopment and attachment to the substrate, nanoscale silicone resin networks can retard material decomposition because of their high durability. Since damage caused by hydrophobic measures can be virtually ruled out if the treatments are properly applied, the organosilicon compounds used in masonry protection will become more and more widely used. 

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