Sarfaraz Alam

High temperature matrix resins based on bispropargyl ethers – part 1: Effect of copper salts on the thermal polymerisation of bispropargylether of bisphenol-A and the thermal stability of these polymers

The compound bispropargyl ether of bisphenol-A (BPEBPA) is prepared using phase transfer catalyst. Different copper salts like cuprous chloride (CuCl), cupric chloride dihydrate (CuCl2.2H2O), copper sulphate pentahydrate (CuSO4.5H2O), basic copper carbonate (CuCO3.Cu(OH)2), cupric acetate monohydrate ((CH3COO)2Cu.H2O), and cupric oxide (CuO) are blended separately with BPEBPA (1%, w/w) and the curing characteristics of these materials are investigated using differential scanning calorimetry (DSC). The presence of copper salt in BPEBPA shifts the curing temperature to a lower temperature region. The materials are thermally cured and the structural characterisation and the thermal properties of these cross-linked materials are investigated using Fourier-transform infrared (FTIR) spectrophotometer and thermogravimetric analyzer (TGA). Of the different copper salts investigated, the presence of copper sulphate pentahydrate in BPEBPA increases the thermal stability of the cured BPEBPA. The thermal degradation products of thermally cured pure BPEBPA and copper salts containing BPEBPA are studied using TG-FTIR. The phenols, substituted phenols, carbon monoxide (CO), carbon dioxide (CO2), and alkenes are major volatiles evolved during the thermal degradation of these materials.

Synthesis and Polymerization of Bismaleimide Derived from 5(6)-amino-1(4′-aminophenyl)-1,3,3′-trimethyl indane

The acid-catalyzed dimerization of α-methyl styrene led to the formation of trimethyl phenyl indane, which on nitration followed by reduction using hydrazine hydrate gave 5(6)-amino-1(4′-aminophenyl)-1,3,3′-trimethyl indane. This aromatic diamine was used to synthesize bismaleamic acid and imidized to yield bismaleimide. The bismaleamic acid was converted to prepolymer directly by imidizing it in refluxing toluene. All the materials synthesized were characterized using FTIR, 1H and 13C NMR. The direct inlet mass spectral characterizations were carried out for bismaleamic acid, bismaleimide and bismaleimide prepolymer. The fragmentation pattern was discussed in detail and the structure proposed was confirmed. The thermogravimetric studies were done for all the materials and kinetic parameters (energy of activation and frequency factor) were calculated using Dharwadkar and Kharkhanavala method. The structural changes occurring in the thermally polymerized bismaleimide and bismaleimide prepolymer were discussed.

Interrelation of scanning electron micrographs with flexural behavior of ferrite and nano-barium titanate reinforced poly-ether-ether-ketone (PEEK) composites

The flexural behavior of ferrite filled poly-ether-ether-ketone (PEEK) composites, with and without reinforcement of nano-barium titanate, was studied and was corroborated through scanning electron microscopy (SEM). In this study, ferrite filled PEEK, and ferrite and nano-barium titanate reinforced PEEK composites were prepared. Ferrite filled PEEK composites showed reduction in flexural strength and increase in flexural modulus with the increase in ferrite content, whereas, with the reinforcement of nano-barium titanate, flexural strength increased and flexural modulus decreased at similar ferrite content. The SEM micrographs corroborated well with flexural behavior, as ferrite particles and smooth topographic surfaces of brittle fracture were evident in the samples having higher ferrite content in ferrite filled PEEK composites, whereas, typical yield pattern of crust and trough on fractured topographic surfaces of ferrite and nano-barium titanate, reinforced PEEK composites, was visible.

Correlation in Morphology and Thermal Behavior of Nanoclay-reinforced Polyetherimide Nanocomposites

Organoclay (Cloisite 30B)-reinforced polyetherimide (PEI) and pristine nanoclay (K10)-reinforced PEI nanocomposite films were made by solution casting process with 0.5, 1.0, 2.0, and 3.0 wt% values of nanoclay. Scanning electron micrographs showed that Cloisite 30B was uniformly dispersed in PEI/Cloisite 30B nanocomposites. Glass transition temperature (Tg) of PEI/Cloisite 30B nanocomposites was observed to be higher than those of neat PEI and PEI/K10 nanocomposites. Tg remained unchanged for all wt% values of Cloisite 30B, whereas Tg of PEI/K10 kept on reducing with increasing values of the content of K10. Wide angle X-ray diffraction and transmission electron micrographs showed intercalation and exfoliation, of Cloisite 30B, which restricted the diffusion of heat through silicate layers to achieve high thermal stability of PEI/Cloisite 30B nanocomposites over PEI/K10 nanocomposites in thermogravimetric analysis and isothermal aging.

High-temperature matrix resins based on bispropargyl ethers (BPEs) – part 2 Curing kinetics of structurally diverse BPEs and their blends with bismaleimide

Structurally diverse bispropargyl ethers (BPEs) using resorcinol, quinol, 4,4′-dihydroxy biphenyl, bisphenol-A, 4,4′-dihydroxy diphenyl ketone, 4,4′-dihydroxy diphenylsulphone, trimethyl indane bisphenol and tetramethyl spirobiindane bisphenol were synthesized, and it was separately blended with 4,4′-bismaleimido diphenyl methane (BMIM) in mole ratios (0.5:0.5). The structural characterizations of the materials are carried out using Fourier transform infrared and nuclear magnetic resonance studies. Differential scanning calorimetric analysis shows that the difference in the melting characteristics and decrease in the curing window for different BPEs were caused by the incorporation BMIM. Addition of BMIM to BPEs reduces the heat liberated during the thermal curing. The curing kinetics is investigated using Flynn–Wall–Ozawa, Vyazovkin and Friedman methods. Amongst the various BPEs investigated, the activation energy (E a) values obtained from spirobiindane BPE (SPIPE) behaves entirely in a different manner compared to all other materials investigated. The apparent E a values for SPIPE was observed to increase with increasing extent of reaction up to 0.2–0.5 and then the E a values decrease with increasing extent of reaction up to 0.55–0.8. The E a for the polymer blends obtained by the incorporation of BMIM with different BPEs shows nearly linear increase in the E a value, and the rate of increase is influenced by the structure of the aromatic spacer present in between the propargyl groups.

Synthesis of silicon-containing bisnadiimide

Silicon-containing thermosetting bisnadiimide (BNI) was synthesized using Bis (amino propyl) tetramethyl disiloxane and nadic anhydride, and fluorine-containing thermoplastic polyamic acid (FPA) was synthesized from 4,4′-(hexafluoroisopropylidene) bis phenoxy dianiline and 4,4′-(hexafluoroisopropylidene) dipthalic anhydride [6-FDA]. The semi-interpenetrating network (s-IPN) systems in various ratios were prepared via solution casting of FAA and crosslinkable BNI, and then curing them up to 370xa0°C in order to achieve an optimum combination to be used for advanced high temperature composite applications. The polyimides and s-IPN were characterized using NMR and FTIR spectroscopy. The thermo-oxidative and water uptake properties of these polyimides and s-IPNs were investigated. The thermogravimetric analysis (TG) showed increase in thermal stability with the increase in thermoplastic polyimide proportion.

Processing of Polyetherimide/Cloisite 30B Nanocomposite by Vibration Casting Method

Abstract Vibration casting method was developed for making polyetherimide (PEI)/Cloisite 30B nanocomposite. Towards this, a vibration casting apparatus was designed and developed. Vibration casting apparatus provided vibrational energy and heat, simultaneously. The processing parameters were established for vibration casting in terms of frequency of vibration, temperature, time and viscosity of casting mixture. Casting mixture of PEI/Cloisite 30B/N,N-dimethyl acetamide (DMAc) was made by dissolving PEI in DMAc and then mixing Cloisite 30B in this solution. The viscosity of PEI/Cloisite 30B/DMAc mixture was optimized for casting by controlling the volume fraction of PEI in DMAc. Morphology of PEI/Cloisite 30B nanocomposite was examined by wide angle X-ray diffraction, transmission electron microscopy, scanning electron microscopy and contact angle measurement. Mechanical and thermal properties of PEI/Cloisite 30B nanocomposite were also compared with that of neat PEI to ascertain the efficacy of vibration casting method.