Two types of polybenzoxazine films, PBa and PPd, that were prepared by the thermal cure of benzoxazines, Ba and Pd, were carbonized at temperature-controlled condition, and the effect of the chemical structure of the polybenzoxazines on carbonization was examined by comparing with the carbonization behavior of polyimide film. X-ray diffraction and X-ray photoelectron spectra measurements showed that the carbon films prepared by heat treatment of rigid polybenzoxazine, PPd, at 900 °C and 1000 °C were the most graphitized. Micrographitic structure was confirmed by transmission electron microscope observation for the carbonized films of PBa and PPd at 1000 °C.
A novel polyfunctional benzoxazine monomer, OP‐a, is synthesized from aniline, formaldehyde, and an oligonuclear phenolic compound (OP) with a 4,4′‐dimethylenebiphenyl group as the phenol linker. After thermal curing of OP‐a up to 240 °C, a brown‐colored, transparent polybenzoxazine (POP‐a) film is obtained. The mechanical and thermal properties of the POP‐a film are investigated by tensile test, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The POP‐a film is extremely tough compared with a typical polybenzoxazine (PB‐a) film. The elongation at break of the POP‐a film is 7.6%, which is surprisingly large for the highly cross‐linked thermoset. The high cross‐link density is suggested from the very high storage modulus (over 1 GPa) above the glass transition temperature (T
g) observed by DMA. The T
g of POP‐a is also improved significantly to T
g = 223 °C, which is approximately 50 °C higher than that of PB‐a. Moreover, TGA reveals that the thermal stability of POP‐a is also enhanced.
Front Cover: In article https://doi.org/10.1002/macp.201800317, Takehiro Kawauchi, Tsutomu Takeichi and co‐workers report that a novel polyfunctional benzoxazine yields a remarkably tough polybenzoxazine thermoset film with much improved thermal properties. The benzoxazine is synthesized using an oligonuclear phenolic compound which is commercially available as a curing agent for epoxy resin.
The aim of this study was to analyze improvement prediction on contour deformation accuracy using deformable image registration (DIR) results compared to rigid image registration (RIR) results. Method: Radiotherapy plans for 31 cases (seven head and neck cases, 10 chest cases, six abdomen cases and eight female pelvis cases) from the privately open database for DIR were used. These cases used at least two radiotherapy plans, and registration was performed using two plans, not only for one case but also for different cases. The DIR and RIR were performed using the DIR software MIM Maestro (MIM software Inc., Cleveland, USA). The registration results for the following organs were analyzed: eye balls, optic nerves, brain stem, spinal cord and right and left parotid glands for head and neck; right and left lungs for chest; liver and right and left kidneys for abdomen; and rectum and bladder for pelvis. Dice similarity coefficient (DSC) for the organs was calculated from the results of RIR and DIR. The improvement in the DSC was observed. Results and discussion: DIR improved the DSC values by more than 0.2 for simple shapes, well-defined boundaries and large volumes such as eye balls, brain stem, lungs and liver. The minimum DSC for these organs was approximately 0.7. The improvement in DSC for the organs eye balls, brain stem, lungs and liver had ceiling values 0.95, 0.90, 1.0 and 1.0, respectively. DSC for the spinal cord, parotid gland, bladder and kidney also improved by DIR compared to RIR; however, DIR could not improve the DSC value for rectum compared to RIR because of a large difference in the position, shape and size due to stool and gas.
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