MODIFICATION WITH LIQUID RESINS

In the modification with liquid thermosetting resins, considerable amounts of polymerisable low-molecular weight polymers or prepolymers are added in a liquid form to cement mortar and concrete during mixing. The 

---

Choice of the Lignin Modification Reaction. The phenolysis reaction was selected as a means of modifying the structure and reactivity of the ammonium lignin sulfonate for three main practical reasons. First, because this lignin derivative is soluble in (and will ultimately be used in conjunction with) liquid phenol itself second, because unreacted phenol, unlike other reaction solvents, would not have to be removed from the phenolated product after reaction and before conversion to the adhesive resin and third, because lignins and carbohydrates are known to react with phenols under acidic conditions (6,7). 

Sin Sinh, L. H., Son, B. T., Tmng, N. N., Lim, D.-G., Shin, S. H., Bae, J.-Y. Improvements in thermal, mechanical, and dielectric properties of epoxy resin by chemical modification with a novel amino-terminated liquid-crystalline copoly (ester amide). Reactive Ftmctional Polym. 72 (2012) 542-548. 

K. Dusek, et al., "Modification of Epoxy Resins with Liquid Rubbers Having Carboxyl Groups. Part I. Preparation of the Mixtures, Curing and Morphology of the Cured Resins," Chemicky Prumysl, 30/55, No. 11, 591-597 (1980). 

Liquid crystals exhibit a partially ordered state (anisotropic) which falls in-between the completely ordered solid state and completely disordered liquid state. It is sometimes referred to as the fourth state of matter . In recent years, interest in liquid crystalline thermosets (especially liquid crystalline epoxy) has increased tremendously [33-44]. If the liquid crystal epoxy is cured in the mesophase, the liquid crystalline superstructure is fixed permanently in the polymer network, even at higher temperature. Liquid crystal epoxies are prepared using a liquid crystal monomer [33-38] or by chemical modification of epoxy resin [43] which incorporates liquid crystal unit in the epoxy structure. Liquid crystalline epoxy resins with different types of mesogen such as benzaldehyde azine [33], binaphthyl ether [34, 35], phenyl ester [36, 37] and azomethine ethers [38, 39] have been reported. Depending on the chemical nature of the mesogen, the related epoxies display a wide range of thermomechanical properties. The resins can be cured chemically with an acid or amine [40, 41] or by photochemical curing in the presence of a photo-initiator [3]. Broer and co-workers [42] demonstrated the fabrication of uniaxially oriented nematic networks from a diepoxy monomer in the presence of a photo-initiator. 

Figure 3.13 Reaction scheme for synthesis of liquid crystalline epoxy by chemical modification of DGEBA resin. Reprinted with permission from K. Sadagopan, D. Ratna and A.B. Samui, Journal of Polymer Science Part A Polymer Chemistry Edition, 2003, 41, 3375 2003, John Wiley and Sons Publishers...

Source Reprinted from Eur Polym J, 38, Chikhi N, Fellahi S and Bakar M, Modification of epoxy resin using reactive liquid (ATBN) rubber, 251-264, Copyright (2002), with permission from Elsevier. 

In the range of aromatic resins, a special significance is held by the modification with phenolic or phenol-formaldehyde resins. Unsaturated aromatic fractions (styrene-indene, indene-coumarone), mixed with phenol polymerize in the presence of Lewis or Bronsted acids (H2SO4, HCl, AICI3, or activated zeolites). Having removed the nonpolymerizable fraction, two fractions can be separated a liquid one (isolated by vapors bubbling) and another, solid, one. Both fractions... 

Both carboxyl and amine liquid polymers have provided chemistries amenable to elastomer modification, with the polybutadiene—acrylonitrile copolymer providing solubility parameters close to if not equaling those of base epoxy resins. 

---