Flexible polybenzoxazine thermosets containing pendent aliphatic chains

Abstract

The rich chemistry of polybenzoxazines allows a wide range of molecular structure design by using appropriate starting materials. A new class of polybenzoxazines has been developed from benzoxazine monomers containing pendent long aliphatic chains. The monomers have been synthesized by the reaction of phenol or bisphenol A with two different long-chain aliphatic amines. The chemical structure of the monomers was confirmed by 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy. The polymerization behavior of the monomers studied by differential scanning calorimetry shows exothermic peaks due to the ring-opening polymerization of benzoxazine monomers centered at 247-255 • C. Dynamic mechanical analysis indicated that the glass transition temperatures T g were in the range 81-92 • C. The thermal stability of the polymers was also examined by thermogravimetric analysis, demonstrating that the weight loss temperatures decreased in comparison with that of traditional polybenzoxazine.

Synthesis and characterization of novel biobased benzoxazines from cardbisphenol and the properties of their polymers

“…Fig. They found that the T g s of the resulting polybenzoxazines were in a range from 66 C to 101 C. 30,31 Agag et al reported that T g s of the polybenzoxazines containing pendent aliphatic chains were in a range from 81 C to 92 C. 32 Interestingly, the result of tan d curves showed that T g s of PCBB and PCBF were 94 C and 121 C, respectively (Fig. In general, a exible polybenzoxazine shows a low T g due to the poor thermal stability.…”

“…In general, a exible polybenzoxazine shows a low T g due to the poor thermal stability. 16,[30][31][32] In order to better understand the above phenomenon, crosslink density r(E 0 ) can be estimated from the rubbery plateau storage modulus at T g + 40 C according to the theory of rubbery elasticity (eqn (2)) as follows: [33][34][35][36] They found that the T g s of the resulting polybenzoxazines were in a range from 66 C to 101 C. 30,31 Agag et al reported that T g s of the polybenzoxazines containing pendent aliphatic chains were in a range from 81 C to 92 C. 32 Interestingly, the result of tan d curves showed that T g s of PCBB and PCBF were 94 C and 121 C, respectively (Fig.…”

Integrating plant oils into thermally curable main-chain benzoxazine polymers via ADMET polymerization

“…polyurethane [10,11] and polysiloxane [12]) into its thermosetting matrix to form a phase-separated morphology. Alternatively, the design of inherently tough polybenzoxazines by preparing benzoxazine monomers [13][14][15] or preferably prepolymers containing flexible segments has also been proposed. Thus, developing thermally curable polymeric precursors with benzoxazine units either as side chain [16] or as chain-end [17][18][19][20] or in main chain [21][22][23][24][25][26][27][28][29] some properties that are the combination of thermoplastic and thermosetting polymers such as processability, flexibility, high crosslinking density after cure, reductions in the vapor pressure during process and fragility for cured-structures are transferred to the cured resin.…”

Synthesis, curing behavior, and thermal properties of fluorene-based benzoxazine-endcapped copoly(ether ketone ketone)s

“…A numerous studies have been conducted aiming to improve the toughness of the polybenzoxazine thermosets. The first one is related to the preparation of novel benzoxazine monomers containing aliphatic soft segments which can afford much tougher polybenzoxazines [22][23][24]. The second one is based on the incorporation of some elastomeric or thermoplastic polymers into the polybenzoxazine structure such as the use of rubber [25], polyurethane [26], polysiloxane [27], polysulfone [28], and poly(epsilon-caprolactone) [29] as the toughening agent blending with benzoxazine monomers.…”