Polymer composites epoxy-based

Polymer-matrix composites for aerospace and transport are made by laying up glass, carbon or Kevlar fibres (Table 25.1) in an uncured mixture of resin and hardener. The resin cures, taking up the shape of the mould and bonding to the fibres. Many composites are based on epoxies, though there is now a trend to using the cheaper polyesters. 

The effect of polymer-filler interaction on solvent swelling and dynamic mechanical properties of the sol-gel-derived acrylic rubber (ACM)/silica, epoxi-dized natural rubber (ENR)/silica, and polyvinyl alcohol (PVA)/silica hybrid nanocomposites was described by Bandyopadhyay et al. [27]. Theoretical delineation of the reinforcing mechanism of polymer-layered silicate nanocomposites has been attempted by some authors while studying the micromechanics of the intercalated or exfoliated PNCs [28-31]. Wu et al. [32] verified the modulus reinforcement of rubber/clay nanocomposites using composite theories based on Guth, Halpin-Tsai, and the modified Halpin-Tsai equations. On introduction of a modulus reduction factor (MRF) for the platelet-like fillers, the predicted moduli were found to be closer to the experimental measurements. 

To improve the mechanical strength and hardness call for the use of curing agents (usually activated by a bake step after development) in the photopoly-merizing composition. Typical curing agents mentioned have been alkyl hydroperoxides, bifunctional amines, acids, etc. The last class of compounnds have been the most popular additives to the epoxy based polymer compositions. Additionally, the use of inert fillers is also known. 

Among the various applications suggested for hyperbranched polymers are surface modification, additives, tougheners for epoxy-based composites, coatings, and medicines. 

In many cases the use of epoxy materials in so-called field conditions (for industrial, construction sites, etc.) demand an increase in the reaction velocity, which is usually achieved by adding accelerators. At present, the widely used accelerators include alkyl-substituted phenols, benzyl alcohol, carboxylic acids (in particular, salicylic acid), and others. A major disadvantage of these accelerators is their tendency to migrate from the cured epoxy matrix during the exploitation, which could lead to a change in the physical properties of the polymer. They also act as a plasticizer of epoxy-based polymers, and as a result reduce the polymer s chemical resistance. Thus, there is a need for new accelerator-modifiers that can provide faster curing of epoxy-amine compositions without negative side effects, and also improve the properties of the finished product. 

Experimental research was performed on models of reinforced concrete beams (10 x 20 x 120 cm) with polymeric concrete layers. B 25 class concrete was used main longitudinal reinforcement of A-III class was used in the form of two 8-mm diameter rods and the 5-mm diameter stirrups of the same class arranged, so that destruction would be along normal sections. Epoxy-rubber compositions were used as covering layer materials. All compositions were made on ED-20 epoxy-based resin. Besides fiber glass-reinforced plastic glued by ED-20 compositions based on liquid rubbers, RubCon was used. The composition of the polymer layers and some of their mechanical characteristics are given in Table 6.3. 

Ryblev, I., Blank, N., and Figovsky, O. Polymer Compositions Based on Epoxy-Rubber Binders, Building Materials no. 6 (1978) 37-39 (in Russian). 

Among the various applications suggested for hyperbranched polymers are surface modification, additives, tougheners for epoxy-based composites, coatings, and medicines. It has been demonstrated that hydrophobic, fluorinated, hyperbranched poly(acrylic acid) films can passivate and block electrochemical reactions on metal surfaces thus preventing surface corrosion (Bruening, 1997). The lack of mechanical strength makes hyperbranched polymers more suitable as ad-... 

Kunz and Kirschning developed a chemically functionalized monolithic material which is based on a glass/polymer composite [28,29] (refer to Sect. 3.1). This material is available in different shapes including rods, disks, and Raschig rings. The polymeric phase of this composite was chemically functionalized (e.g., substitution of the benzylic chlorine by trimethylamine or sulfonation). Rod-shaped objects were first embedded in a solvent-resistant and shrinkable PTFE tube. This was followed by encapsulation with a pressure-resistant fiber-reinforced epoxy resin housing with two standard HPLC fittings, which created... 

Bug Bugncourt, E., Galy, J., Gerard, J. F., Bathel, H. Effect of sub-micron silica fillers on the mechanical performance of epoxy-based composites. Polymer 48 (2007) 1596-1605. 

Epoxide polymers have been used for many applications such as binders for glass-reinforced plastics, adhesives, impregnating materials, potting compounds, and therefore, the study of their thermal stability, including epoxy-based composites is of great practical interest. 

A large number of vegetable oil-based polymer composites have been reported in the literature. Among these, polyester, polyurethane and epoxies are very important and are discussed in the following sub-sections. 

Researchers are exploring the feasibility of manufacturing epoxidised vegetable oil-based polymer composites. Composite materials have been manufactured utilising vegetable oil-based epoxy resins and a range of... 

Abstract This chapter describes vegetable oil-based polymer nanocomposites. It deals with the importance, comparison with conventional composites, classification, materials and methods, characterisation, properties and applications of vegetable oil-based polymer nanocomposites. The chapter also includes a short review of polymer nanocomposites of polyester, polyurethanes and epoxies based on different vegetable oils and nanomaterials. The chapter shows that the formation of suitable vegetable oil-based polymer nanocomposite can be considered to be a means of enhancing many of the desirable properties of such polymers or of obtaining materials with an intrinsically new set of properties which will extend their utility in a variety of advanced applications. Vegetable oil-based shape memory hyperbranched polyurethane nanocomposites can be sited as an exampie of such advanced products. 

---