Methylol‐functional benzoxazines as precursors for high‐performance thermoset polymers: Unique simultaneous addition and condensation polymerization behavior
Journal ArticleA new class of high‐performance resins of combined molecular structure of both traditional phenolics and benzoxazines has been developed. The monomers termed as methylol‐functional benzoxazines were synthesized through Mannich condensation reaction of methylol‐functional phenols and aromatic amines, including methylenedianiline (4,4′‐diaminodiphenylmethane) and oxydianiline (4,4′‐diaminodiphenyl ether), in the presence of paraformaldehyde. For comparison, other series of benzoxazine monomers were prepared from phenol, corresponding aromatic amines, and paraformaldehyde. The as‐synthesized monomers are characterized by their high purity as judged from 1H NMR and Fourier transform infrared spectra. Differential scanning calorimetric thermograms of the novel monomers show two exothermic peaks associated with condensation reaction of methylol groups and ring‐opening …
Mohamed Saad Saad Baqar, (06-2012), Journal of Polymer Science Part A: Polymer Chemistry: Wiley, 50 (11), 2275-2285
Influence of Cr, Mn and Mo Addition on Structure and Properties of V Microalloyed Medium Carbon Steels
Journal ArticleThe effect of austenitizing temperature and Cr, Mo and Mn addition on microstructure and mechanical
properties of V microalloyed medium carbon steel has been studied by means of metallography and mechanical
testing. The addition of Cr, Mn and Mo leads to a decrease in yield strength (YS) by approximate 100 MPa in
comparison to the base steel. It is assumed that Mn and Mo increase hardenability by promoting the formation
of bainitic sheaves (BS), i:e: by suppressing the formation of ferrite-pearlite and acicular ferrite (FP-AF). Cr
at the level used in this work is not that e®ective. Presence and packet size of bainitic sheaves decrease
the Charpy V-notch impact energy at 20 ±C (CVN20) in comparison to ferrite-pearlite and acicular ferrite
microstructures.
Abdulnaser Hamza Ahmed Fadel, Dragomir Glisi, Nenad Radovic, Djordje Drobnjak, (03-2012), J. Materials. Science. Techno,: Elsevier, 28 (11), 1053-1058
Poly (benzoxazine-co-urethane) s: A new concept for phenolic/urethane copolymers via one-pot method
Journal ArticleHistorically, applications for traditional phenolic resin/polyurethane materials are limited due to the inherently weak thermal stability of urethane-phenolic linkage and slow reaction rate. A novel concept has been developed to produce phenolic resin/polyurethane copolymers ...
Mohamed Saad Saad Baqar, (01-2011), Polymer: Elsevier, 52 (2), 307-317
Effect of neighboring groups on enhancing benzoxazine autocatalytic polymerization
ChapterThe unique features of polybenzoxazines make them attractive for a wide range of applications. The characteristics of polybenzoxazines such as excellent dimensional stability, lower surface energy, higher Tg, and lower moisture absorption are attributed to the stable intramolecular hydrogen bonding in their network structure. The features make polybenzoxazines excellent candidates for the applications that require near zero shrinkage and high dimensional stability. Polybenzoxazines are formed by the autocatalytic polymerization of benzoxazine monomers. Polybenzoxazines are well known as a new class of thermoset polymers used for high performance applications. They provide the characteristic properties found in phenolic resins, such as high thermal stability, excellent electrical properties, good mechanical properties, and better flame retardancy. Furthermore, they have the advantages …
Mohamed Saad Saad Baqar, (01-2011), Handbook of Benzoxazine Resins: Elsevier, 193-210
Static Recrystallization in Nb/Ti low Carbon Micro alloyed Steel
Conference paperActivation energy for static recrystallization estimated in this work of 281kJ/mol is in excellent agreement with previously reported data (both experimental and mdeled) and indicates that difusion of Nb in austenite is most probably the rate controlling process
Abdunnaser H. Fadel, (05-2010), Serbia: Association of Metallurgical Engineers of Serbia (AMES), 13-18
Influence of Reheating Temperature and Vanadium Content on Transformation Behavior and Mechanical Properties of Medium Carbon Forging Steels
Journal ArticleThe influence of vanadium and nitrogen on microstructure and mechanical properties of medium-carbon
steels has been studied by means of metallography and mechanical testing. Vanadium addition to the low
nitrogen steel suppresses the formation of ferrite–pearlite following the low reheating temperatures and microstructure
consists of bainitic sheaves. Increasing nitrogen at the same vanadium level promotes the acicular
ferrite formation. For high reheating temperatures, dominantly acicular ferrite structure in both the low
nitrogen and the high nitrogen vanadium steels is obtained. The results suggest that vanadium in solid solution
promotes the formation of bainite. The effect of nitrogen is related to the precipitation of VN particles in
austenite with high potency for intragranular nucleation of acicular ferrite and to the precipitation of V(C, N)
particles in ferrite with high potency for precipitation strengthening. Addition of both vanadium and nitrogen
considerably increases the strength level, while CVN20 impact energy increases on changing the microstructure
from bainitic ferrite to the fine ferrite–pearlite and acicular ferrite.
Abdulnaser Hamza Ahmed Fadel, (04-2010), Japan: ISIJ International, 4 (50), 601-606
Influence of V and N on Transformation Behavior and Mechanical Properties of Medium Carbon Forging Steels
Journal ArticleThe influence of vanadium and nitrogen on microstructure and mechanical properties of
medium-carbon steels has been studied by means of metallography and mechanical testing.
Vanadium addition to the low nitrogen steel suppresses the formation of ferrite-pearlite following
the low reheating temperatures and microstructure consists of bainitic sheaves. Increasing nitrogen
at the same vanadium level promotes the acicular ferrite formation. For high reheating temperatures,
dominantly acicular ferrite structure in both the low nitrogen and the high nitrogen vanadium steels
is obtained. The results suggest that vanadium in solid solution promotes the formation of bainite,
whereas the effect of nitrogen is related to the precipitation of VN particles in austenite with high
potency for intragranular nucleation of acicular ferrite and to the precipitation of V(C,N) particles in
ferrite with high potency for precipitation strengthening. Addition of both vanadium and nitrogen
considerably increases the strength level, while CVN20 impact energy increases on changing the
microstructure from bainitic ferrite to the fine ferrite-pearlite and acicular ferrite.
Abdulnaser Hamza Ahmed Fadel, (01-2010), Switzerland: Materials Science Forum, 1 (638), 3459-3464