Development of epoxy‐cyanate ester‐clay nanocomposites offering enhanced thermally stability

Abstract

The preparation and characterization of blends of a series of dicyanate monomers such as 2,2 0 -bis(4-cyanatophenyl) propane (DCDPP), bis-4-cyanato-biphenyl (DCBP), bis-4-cyanatonaphthalene (DCN), 3,3 0 -bis(4-cyanatophenyl)sulphide (DCTDP), 3,3 0 -bis (4-cyanatophenyl)sulphone (DCDPS), and the diglycidyl ether of bisphenol A are reported. These copolymers are combined with a montmorillionite nanoclay and both epoxy-cyanate blends and epoxy-cyanate blends-nanoclay composites are all analyzed for thermal stability, thermal degradation kinetics, flame retardancy, and impact strength. The nanocomposites are further characterized by X-ray diffraction and SEM to determine morphological features, from which structure-property relationships are determined. Dispersion of the nanoclay is of paramount importance, but its inclusion serves to improve char yield and impact strength, when this is achieved.

Examining the thermal degradation behaviour of a series of cyanate ester homopolymers

“…The thermal decomposition of aromatic polycyanurates goes through a common mechanism which begins with thermolytic cleavage of the resin backbone and culminates with decyclization of the cyanurate rings around 300 °C, followed by char formation; these data are in good agreement with previous reports . However, the other onsets can be attributed to two different species already present in the treated sample and not formed only during TGA execution, which showed the first onset around 450 °C corresponding to decomposition into gaseous sulfonyl‐dibenzene or propane‐2,2‐diyldibenzene units.…”

“…A plot of ln[ln(1 /y )] in the case of Broido's method, ln[−(1 – y )/ T 2 ] in the case of the Coats–Redfern method and 1 – y in the case of the Horowitz–Metzger method versus 1000/ T for major degradation events yielded plots with linear portions. The changes in gradients are consistent with the different steps in the thermal degradation mechanism . The cured samples of the homopolymer systems were subjected to the kinetic analysis and are shown in Fig.…”

“…The thermal decomposition of aromatic polycyanurates goes through a common mechanism which begins with thermolytic cleavage of the resin backbone and culminates with decyclization of the cyanurate rings around 300 ∘ C, followed by char formation; wileyonlinelibrary.com/journal/pi these data are in good agreement with previous reports. [25][26][27] However, the other onsets can be attributed to two different species already present in the treated sample and not formed only during TGA execution, which showed the first onset around 450 ∘ C corresponding to decomposition into gaseous sulfonyl-dibenzene or propane-2,2-diyldibenzene units. The char yields observed are typical for di-functional aromatic dicyanate homopolymers and DCN-HP, with the highest aromatic content, predictably shows the highest char yield (Table 1); DCDPP-HP, with the greatest aliphatic character, shows the lowest.…”

“…17,18 The trend for increased use of cyanate esters is due to the growing demand for lightweight, low dielectric loss, high heat resistant structures for manufacturing military aircraft. 4,[19][20][21][22][23][24][25][26] Consequently, in this study, a detailed and systematic evaluation is analysed and discussed, especially concerning the thermal properties of the homopolymers.…”

Facile strategy and mechanism of greatly toughening epoxy resin using polyethersulfone through controlling phase separation with microwave‐assisted thermal curing technique

“…Thermally resistant thermosetting resins (TRRs) have been key and base materials for many cutting‐edge industries such as aerospace, electronic information, automotive and new energy fields . However, TRRs generally have poor toughness due to highly crosslinked structure . In order to improve toughness without degrading heat resistance of TRRs, engineering thermoplastics with good heat resistance, such as polyethersulfone (PES), polysulfone, polyetheretherketone, and polyetherimide have been utilized to toughen thermosetting resins, and many valuable achievements in theoretic and industrial aspects have been obtained.…”