Wen-bin Liu

Synthesis of novel furan-containing tetrafunctional fluorene-based benzoxazine monomer and its high performance thermoset

A novel furan-containing tetrafunctional fluorene-based benzoxazine monomer with bisphenol- and diamine-type oxazine rings was successfully prepared. The resulting polybenzoxazine exhibits extremely higher glass transition temperature (440 °C) and better thermal stability than difunctional furan-containing fluorene-based and traditional multifunctional benzoxazine resins.

Synthesis, curing kinetics and thermal properties of novel difunctional chiral and achiral benzoxazines with double chiral centers

Novel difunctional chiral and achiral benzoxazine monomers were synthesized from the reaction of bisphenol A with paraformaldehyde and primary amines, including S-(+)-3-methyl-2-butylamine and rac-(±)-3-methyl-2-butylamine, by solventless method. The chemical structures of chiral and achiral benzoxazines were identified by fourier transform infrared, nuclear magnetic resonance (1H NMR and 13C NMR). The curing behavior and non-isothermal curing kinetics of chiral and achiral benzoxazine monomers were investigated by differential scanning calorimeter (DSC). Isoconversional methods based on Friedman and Kissinger–Akahira–Sunose were applied to analyze the curing process of chiral and achiral benzoxazines. The thermal properties of cured polymers were characterized by DSC and thermogravimetry. The results suggested that the optical purity and stereo-configuration for chiral and achiral benzoxazines have definite influence on curing behavior and thermal properties despite the same chemical structure. Chiral benzoxazine displayed typical characteristics of difunctional benzoxazines. Achiral benzoxazine showed distinctly double peaks in DSC exotherms due to the presence of racemic and mesomeric isomers. The thermal properties of achiral polybenzoxazine were slightly higher than those of chiral polybenzoxazine, and were much higher than those of other bisphenol A-C3–C8 linear aliphatic amine-based polybenzoxazines because of tight packing, low free volume, and abundant intramolecular and intermolecular hydrogen bonds in network structure of polymers.

Preparation and properties of chitosan particle-reinforced polybenzoxazine blends

This study investigates the effects of chitosan particles (CTS) on the curing behavior, thermal and thermomechanical properties of polybenzoxazine matrix. The morphological, thermomechanical, and thermal properties of the blends are analyzed using scanning electron microscopy (SEM), dynamic scanning calorimetry (DSC), dynamical mechanical analyzer (DMA), and thermogravimetric analysis (TGA). The results show that the −NH2 groups on the chitosan can act as an active crosslinking position and hydrogen bonding. The SEM micrographs reveal good compatibility between the blend components. Furthermore, the values of glass transition temperatures, char yields, and storage moduli of the cured blends are found to be increased with the increase of CTS contents to reach 191℃, 34%, 4.3u2009GPa, respectively, at 10% of CTS content.

Preparation and Thermal Properties of Polybenzoxazine/TiC Hybrids

In this work, typical polybenzoxazine, as new class of phenolic resin, has been used as a matrix for preparing a series of high performance hybrid materials using various amounts of titanium carbide (TiC) ranging between 0-10 wt% as fillers, via a solution blending technique. The thermal properties of bisphenol A-aniline base benzoxazine monomers (BA-a) and TiC mixtures have been studied by differential scanning calorimetry (DSC). The thermal stability of their cured hybrids has been tested by means of thermogravimetric analysis (TGA). The result showed that the glass transition temperature of the prepared composites increased with increasing the amount of TiC to reach a higher value at 194°C. Also, the incorporation of TiC nanoparticles has considerably improved the thermal stability of the hybrids including the char yield which increase by 50 % at 10 wt% TiC content.

Chapter 28 – Furan-Based Benzoxazines

With the increasing environmental awareness and the fast depletion of petroleum resources, bio-based polymers synthesized from renewably derived chemicals have entered our awareness gradually. Among all renewable resources, furan-containing compounds such as furfuryl alcohol and furfurylamine, which is derived from a variety of agricultural by-products such as corncobs and wheat bran, have been widely used as the precursors of polymers with high-performance. In this chapter, the structure, polymerization, thermal, and thermomechanical properties of various furan-containing, bio-based benzoxazines are briefly introduced. The synthesis, characterization, polymerization behavior, thermal, and thermomechanical properties of a series of novel furan-containing, tetrafunctional fluorene-based oxazine monomers and their polymers that simultaneously contain benzoxazine and fluorene-oxazine are mainly described. By means of the introduction of furan rings and more oxazine rings, these cured polymers and copolymers with typical monofunctional polybenzoxazine (P-a) display an extremely higher Tg value (442°C) and a much better thermal stability than those of traditional difunctional and multifunctional polybenzoxazines due to much more cross-linked sites.

Fluorene-Based High Molecular Weight Benzoxazine Blends

The recent development of high-molecular weight benzoxazine precursors is discussed in this chapter. Also, the studies of fluorene-based benzoxazine monomers and main chain, side chain, and telechelic high molecular weight benzoxazine oligomers and co-oligomers containing fluorene groups are reviewed in detail. Compared with fluorene-based benzoxazine and fluorene-oxazine monomers, the fluorene-containing high-molecular weight benzoxazine precursors exhibit better thermal properties. Then these benzoxazine precursors are incorporated into traditional monofunctional benzoxazine, P-a. The curing behavior of the obtained blends are studied by differential scanning calorimeter (DSC). The thermal and mechanical properties of the cured blends are evaluated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). These produced blend resins could be good candidates for high performance thermosets.

Chapter 26 – Chitin- and Shell-Based Benzoxazines

This chapter focuses on the preparation methods and evaluation of the morphological, thermal, and mechanical properties of some natural fillers and biopolymers-reinforced polybenzoxazine materials using different structural, mechanical, and thermal techniques. In addition, reinforcement mechanisms of the typical polybenzoxazine thermoset by these bio-fillers are discussed in detail. Furthermore, the interaction and relationship between these modifiers and the different mechanical and thermal property improvements in their polybenzoxazine blends and composites are scrutinized.