Polymer hardening

Sufficient titanate leads to a fully hardened polymer. Using only enough titanate to react with free hydroxyls, the resin may subsequently be cured at lower cost with conventional cross-linking agents. The titanated epoxy resin has a low power factor, which is important in electrical appHcations, eg, potting components and insulation (see Embedding). Titanates improve adhesion of metals to epoxies. 

Uses Curing and hardening polymers catalytic solvent in chemical synthesis accelerator activators for rubber wetting, penetrating, and waterproofing agents of quaternary ammonium types corrosion inhibitor propellant. 

The ammonia or amine photothermally liberated from a cobalt(III) complex can be used to crosslink a carbonyl-containing polymer. One such complex is (120), which can be used in a photoresist composition where the non-crosslinked polymer is dissolved away, leaving a negative image in hardened polymer.246... 

Chromophores must be thermally robust enough to withstand temperatures encountered in electric field poling and subsequent processing of chromophore/polymer materials. Chromophore decomposition temperatures can be assessed by techniques such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA and DSC measurements on neat chromophore samples in air will tend to yield decomposition temperatures lower than those for the same chromophores in hardened polymer lattices. Typically, to be useful for development of device quality materials, a chromophore must exhibit thermal stability of 250 °C or higher (with thermal stability defined as... 

In Fig. 19, uncrosslinked refers to the situation where only one end of the chromophore is attached to the polymer backbone (prescursor polymer) while crosslinked refers to the situation where both ends of the chromophore are attached to the polymer backbone (final hardened polymer) [138]. The double-end crosslinking results in improvement in the dynamic thermal stability by more... 

Resin Certain liquid prepolymer products, such as epoxies and unsaturated polyesters, which are subsequently cross-linked to form hardened polymer. 

Figure 8.3 Schematic diagram of ultra rapid-hardening polymer-modified shotcrete system.

Alternatively, chemical cross-linking reactions can also be used to harden polymer dispersions (oxidative drying or oven drying). An example is the cross-linking of hydroxyl groups of the polymer dispersions with hexamethoxymethylmelamine resins. 

These equations are in their simplest usable form. The original equations of Flory took into account also the density of the hardened polymer. It has been disregarded here as it is of no consequence in the formulation of thermosetting adhesives discussed later. 

Boquillon, N. and Fringant, C. (2000) Polymer networks derived from curing of epoxidised linseed oil influence of different catalysts and anhydride hardeners. Polymer, 41(24), 8603-8613. 

A further application using microdroplets is the rapid prototyping of three-dimensional industrial objects making use of the ejection of high-temperature liquid metals, ceramic suspensions or hardenable polymers. 

Kodama, H (1981) Automatic method for fabricating a three-dimensional plastic model with photo-hardening polymer. Rev Sci Instrum 52 1770-1773... 

Kobayashi, M., Takahashi, T., Takimoto, J., Koyama, K., Influence of glass beads on the elongational viscosity of polyethylene with anomalous strain rate dependence of the strain-hardening. Polymer 37 (1996) 3745. 

The study of phase size and compatibility requires that the different phases be observed, distinct from one another, and that there is minimum distortion in the polymers. However, multiphase polymers often cannot be stained or sectioned uniformly. There are composite structures that are combinations of soft rubbers, coatings and oriented fibers which caimot be stained with a single staining agent and the sections may be deformed or distorted, limiting both observation and interpretation. The ebonite method was developed by Smith and Andries [111] to stain and uniformly harden polymers. 

Figure 16.27 The effect of adding strain-rate hardening polymers to homopolymer polypropylene allowing increasing ability to stretch into deep cavities.

Christanti, Y., Walker, L. M. (2001). Surface tension driven jet break up of strain-hardening polymer solutions. Journal of Non-Newtonian Fluid Mechanics, 100, 9-26. 

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