Highly processible maleimide and nitrile functionalized benzoxazines for advanced composites applications

Maleimide and 2‐aminobenzonitrile (MIan)‐based benzoxazine has been synthesized and characterized. MIan contains imide, oxazine, and nitrile functional groups that can react almost simultaneously, leading to complicated reaction mechanisms. For understanding the fundamental polymerization mechanism, the model benzoxazine compound is synthesized. The ortho‐nitrile group in the model compound undergoes cyclization reaction, producing the thermally stable six‐membered ring species resulting in the excellent thermal properties of the material. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Hierarchical architecture of Bi12TiO20 via ethylene glycol-mediated synthesis route

Hierarchical architecture of cubic sillenite bismuth titanate (Bi₁₂TiO₂₀) is successfully synthesized using simple ethylene glycol-mediated self-assembly; followed by calcination under air at 600 °C for 30 min. The products are characterized using field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FT-IR), thermogravimetric-differential thermal analysis (TG-DTA), and X-ray diffraction (XRD). The reaction time has an effect on the product morphology, which changed from a leaf- and circular plate-like structure to a completely formed hierarchical structure within 2 h. The hierarchical structure of Bi₁₂TiO₂₀, having a size around 3 μm, is composed of 2D twist nanoplates, and each twist nanoplate has a thickness around 10–30 nm.     

Synthesis of Fe-Ti-MCM-48 from silatrane precursor via sol-gel process and its hydrothermal stability

A series of bimetallic Fe–Ti-MCM-48 materials was successfully synthesized via sol–gel method using cetyltrimethylammonium bromide (CTAB) as a template and silatrane, iron (III) chloride, and titanium (IV) isopropoxide as silica, iron, and titanium sources, respectively. Scanning electron microscopy (SEM) showed the truncated octahedron morphology of Fe–Ti-MCM-48.X-ray diffraction (XRD) patterns showed well-defined, order cubic mesoporous structures. X-ray fluorescence (XRF) revealed the total metal content of the final product. UV–visible absorption spectra confirmed both iron (Fe³⁺) and cerium (Ti⁴⁺) species highly dispersed in the framework, while N₂ adsorption/desorption measurements indicated a high specific surface area. As metal content increased, the mesoporous order and surface area decreased. The synthesized Fe–Ti-MCM-48 with 0.01Fe/Si and 0.01Ti/Si ratio still retained a cubic structure after hydrothermal treatment at 100 °C for 72 h.     

Preparation of polybenzoxazine foam and its transformation to carbon foam

An organic foam derived from a new type of phenolic resin, namely polybenzoxazine, was successfully prepared with a noncomplex and economical foaming method by using azodicarbonamide (AZD) as a foaming agent. The influence of foam density on the physical and mechanical properties of the foams was studied. All resulting polybenzoxazine foams and carbon foams exhibit a tailorable uniform microstructure. Polybenzoxazine foams showed a density in the range of 273–407 kg/m³, and a compressive strength and a compressive modulus in the range of 5.2–12.4 MPa and 268–681 MPa, respectively. The foam density not only affects the physical and mechanical properties, but also affects the deformation response of the foam. In addition, the polybenzoxazine foam was further transformed into carbon foam by carbonization at 800 °C under an inert atmosphere, and its properties were examined.     

Self-Cleaning Properties of Silk Fabrics Functionalized with Tio2/Sio2 Composites

Silk fabrics were treated with TiO₂/SiO₂ composites using the pad-dry-cure method. TiO₂/SiO₂ composites were prepared through a low-temperature sol-gel method with five different TiO₂:SiO₂ weight ratio of 100:0, 70:30, 50:50, 30:70, and 0:100. The photocatalytic self-cleaning properties of the TiO₂/SiO₂ composite of samples were assessed by analyzing the degradation of coffee stain under UV irradiation. The presence of anatase crystalline structure in synthesized composites was confirmed using the X-ray diffraction patterns. Fourier transform infrared study confirmed the existence of Si-O-Si and Ti–O–Si bonds in the composites. Surface modifications were confirmed by scanning electron microscopy images. The EDS spectrum of samples showed a well-defined peak for the carbon, oxygen, titanium, and silicon elements, also indicating the existence of TiO₂/SiO₂ on the treated silk fabrics. The samples treated with TiO₂/SiO₂ (70:30) composite showed the highest efficiency in coffee stain removal, followed by samples treated with TiO₂/SiO₂ (50:50). The laundering durability of treated sample showed the strongly interaction between the silk fabrics and the TiO₂/SiO₂ nanoparticles. The physical properties of treated silk fabrics were investigated.     

High‐performance maleimide and nitrile‐functionalized benzoxazines with good processibility for advanced composites applications

A maleimide and 2‐aminobenzonitrile (MIan) based benzoxazine has been synthesized and characterized. This benzoxazine has maleimide and nitrile functionalities that can polymerize, resulting in a highly crosslinked material. Incorporation of the imide group increases the shear viscosity compared to monofunctional benzoxazines but not as high as difunctional benzoxazines, allowing good processibility, while maintaining excellent mechanical and thermal properties. Catalysts, epoxy copolymerization, and rubber interlayer methods are utilized to optimize the composite properties. The 60% carbon cloth‐reinforced resin has achieved the flexural strength over 1 GPa. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 548–558, 2006