Epoxide Resin Systems Research Articles

高性能エポキシ樹脂

高性能エポキシ樹脂

Mechanical and dielectric relaxations of epoxide resins containing the spiro‐ring structure. II. Effect of the introduction of methoxy branches on low‐temperature relaxations of epoxide resins

AbstractMechanisms for low‐temperature relaxations of three spiro‐ring‐type epoxide resin systems with and without methoxy branches were investigated by comparison with those of a bisphenol A‐type resin system. In the spiro‐ring‐type epoxide resin systems, two well‐defined relaxation peaks, denoted as the β and β′ relaxations, and a shoulder peak were observed at about −70, +60, and 0°C, respectively. The magnitude of the β relaxation was decreased by the introduction of methoxy branches on the phenylene group. This phenomenon could be interpreted as a result of the formation of hydrogen bonds between the hydroxy‐ether group and methoxy branch. Moreover, it was concluded that the β′ relaxation and the shoulder peak are due to the motion of the p‐phenylene group adjacent to the spiro‐ring and of the hydroxy‐ether group blocked by the hydrogen bond, respectively.

Mechanical relaxation properties of spiro-type epoxide resins cured with acid anhydrides

Low-temperature relaxation behaviour has been investigated for a bisphenol-A type and three spiro-type epoxide resins cured with acid anhydrides. In the spiro-type resin systems, one new relaxation, denoted here as the β′ relaxation, is clearly observed near room temperature. It is suggested that the β′ relaxation is related to the motion of p-phenylene group adjacent to the spiro ring. The impact strength of epoxide resin systems that show the β′ relaxation is considerably higher than that of other cured systems and is proportional to the intensity of the β′ relaxation. Consequently, it is concluded that the existence of the room-temperature relaxation such as the β′ relaxation is associated with increased toughness of cured epoxide resins.

Mechanical relaxation mechanism of epoxide resins cured with acid anhydrides. II. Effect of the chemical structure of the anhydrides on the β relaxation mechanism

AbstractThe mechanism of low‐temperature mechanical relaxation of acid‐anhydride‐cured epoxide resins has been investigated in detail. One mechanical relaxation, denoted as the β relaxation, is observed from −80 to −50°C for all epoxide resin systems cured with aromatic, alicyclic, and aliphatic anhydrides. The β relaxation increases in peak height and shifts to higher temperature with increasing molecular volume of the diester segments formed by the reaction of acid anhydrides. From these results, it is concluded that the β relaxation for anhydridecured systems is due to the motion of the diester segment, and that the intensity and peak position of the β relaxation depend on the molecular volume of this segment. Moreover, it was shown that the tensile impact strength of the anhydride‐cured systems is governed by the intensity of the β relaxation of these systems when the parameters Tg and v of these systems are nearly constant.

International and continental specifications for composites 2. Polyester and epoxide resin systems

Resin specifications issued by the ISO and France describe only test methods. Germany issues specifications covering polyester and epoxide resins and the various types of moulding material made from them. A comprehensive series of test methods have also been issued.

USA specifications for composites (4) Military specifications for polyester and epoxide resin systems

USA specifications for composites (4) Military specifications for polyester and epoxide resin systems

USA Specifications for composites: (3) ASTM standards for polyester and epoxide resin systems

ASTM standards are confined to a grading system for epoxide resins and a specification for filled polyester moulding materials.

A review of british standards for composites Part 2 Polyester and epoxide resin systems

A review of british standards for composites Part 2 Polyester and epoxide resin systems

Chemistry of epoxide resins. XVII. Influence of structure and curing conditions on the density, degree of cure, and glass transition temperature during the curing of epoxide resins

AbstractDuring an investigation of various epoxide resin systems, some cases were found in which the room temperature density decreased with increasing curing temperature and increasing degree of cure. In other systems the density was found to be independent of the curing temperature. In these cases it is possible by deliberately stopping the reaction to measure density values which also decrease as the curing progresses. This unexpected behavior can be explained in a purely physical manner from the pattern of the density changes during an entire curing cycle. The density decrease of the noncured mixture, which is due to the increased curing temperature, outweighs all contraction effects consisting of isothermal chemical and cooling shrinkage, whereby the latter is dependent to a great extent on the glass temperature. In those cases where the glass temperature exceeds the curing temperature, the chemical reactions come to a standstill, when the temperature difference reaches a certain value, i.e. it “freezes chemically”. By means of values that can be measured readily at low temperatures, it is possible to construct diagrams from which the variation of the density at higher temperatures of the curing cycle can be estimated.

Some trends in the use of epoxide resins in electronic engineering

Various means of modifying liquid epoxide-resin systems to adapt them for specific uses are illustrated. The use of coal tar as a cheap diluent is described and its effects on some electrical properties of two typical epoxide-resin compositions are shown.Some mechanical and electrical properties of systems containing a new flexible diepoxide resin are indicated. Such systems are of potential interest for the encapsulation of components where good resistance to moderate temperatures and thermal shock is required.The results of the formulation of doughs and powders from liquid epoxide-resin systems are shown by reference to dough moulding compositions, moulding powders and powders for application by the fluidized-bed technique.

Some characteristics of epoxide resin systems

AbstractA discussion is given of the hardening of epoxide resins with amines and of methods of modifying polyfunctional aliphatic amines to widen their range of application. The effects of time and temperature of curing of epoxide resin–amine systems on the properties of the products are briefly discussed.