Molecular and thermal studies of carbon fiber precursor polymers with low thermal-oxidative stabilization characteristics

In this investigation, terpolymers, copolymers, and homopolymer of acrylonitrile with dimethylaminopropyl acrylamide (DMAPA), itaconic acid (IA) viz., poly(acrylonitrile‐ran‐3‐dimethylaminopropyl acrylamide‐ran‐itaconic acid) [P(AN‐DMAPP‐IA)], poly(acrylonitrile‐co‐3, dimethylaminopropyl acrylamide) [P(AN‐DMAPP)] were synthesized with varying amounts of comonomers using solution polymerization process. The chemical structure, composition, bonding network were determined employing infrared, 1H and, 13‐carbon nuclear magnetic resonance spectroscopic techniques. Molecular characteristics of as‐synthesized polymers such as different kinds of average molecular weights, molecular weight distribution were estimated applying solution viscometry and size exclusion chromatography. The influence of comonomers (DMPAA, IA) on the thermal stabilization characteristics of acrylonitrile terpolymers in comparison with copolymers and homopolymers of acrylonitrile were studied using differential scanning calorimetry (DSC), hyphenated thermal techniques (thermal gravimetry coupled with differential thermal analyzer).The DSC curves of P(AN‐DMAPP‐IA) exhibit a distinct broader bimodal peaks with thermal exotherm initiating at as low as 165 °C, and followed by two peaks with temperature difference of 42 °C, releasing the evolved heat at a release rate of 0.7–0.11 J g−1s−1over 10 min as compared to 1.2, 7.5 J g−1s−1 in 4.5, 2 min as observed in P(AN‐DMAPP), polyacrylonitrile, respectively. The thermal stability of P(AN‐DMAPP‐IA) and P(AN‐DMAPP), as evidenced by TGA‐DTA was found to be higher than PAN homopolymers. Specific heat capacity measurements confirmed the DSC results. Bulk densities of P(AN‐DMAPP‐IA) were in the range 0.31–0.35 g/cc. These results confirm the low‐temperature stabilization characteristics and suitability of P(AN‐DMAPP‐IA) as low cost carbon fiber precursor polymer

Towed Acoustic Countermeasures for Defending Acoustic Homing Torpedoes

The growing torpedo threat to ships and submarines demands effective countermeasures for defence. Detection, classification and localisation of an attacking torpedo is the first step towards launching effective countermeasures. Studies are on the rise to use the existing sonar systems to detect torpedoes and subsequently use countermeasures. The use of towed array sonar systems for torpedo detection and acoustic counter measures are the most recent and not reported much in open literature. This paper presents a modular acoustic counter measure approach using towed decoy against acoustic homing torpedoes. Describes the technologies and algorithms required for different modes of towed decoy, which is effective against both active and passive acoustic homing torpedoes. Towed decoy signal generation schemes and their realisation using digital signal processing hardware are outlined in this paper

Hand Book on Aquafarming: Fishery Potential of Andaman & Nicobar Islands

The Marine Products Export Development Authority has been promoting the commercial aquaculture of shrimp as a means for boosting India's seafood exports. At the same time, it is recognised that in order to have a sustained share in the world seafood market, aquaculture of other species, which are in great demand should also be encouraged. It was in this context that a publication titled FISHERY POTENTIAL OF ANDAMAN & NICOBAR ISLANDS was brought out at the time of INDAQUA '93, India's first aquaculture exposition. The publication has been well received and we are now coming out with a reprint of this publication. We are confident that this publication will continue to generate interest in those who intend to take up aquaculture of these speaes to exploit the abundant natural resources available in this countrk for augmenting export production

Kinetics of thermal degradation of 6FDA based copolyimides - I

10.1016/S0141-3910(01)00230-0Polymer Degradation and Stability752273-285PDST

A review on the impact of conductive nanoparticles (CNPs) in anaerobic digestion: Applications and limitations

The development of the anaerobic digestion (AD) process and its mild operating conditions of complex organic carbon distinguish it from conventional energy technologies and make it highly desirable to meet a sustainable green energy technology. Although, the effectiveness of this AD method is often constructed by few issues such as surface heterogeneity, ammonia inhibition, poor methane production, slow microbe growing rates, and slow mass transfer which needs rectification. Conductive nanoparticles (CNPs) helps to increase anaerobic digestion rates as nano-sized structures with specific physicochemical properties interact with the substrate and microorganisms. CNPs as additive have resulted in high efficiency for the AD process because of their unique physicochemical characteristics, i.e. high surface area, high active sites, high reactivity levels, high specificity, self-assembly, increased mobility, and AD media transmission. This review concentrates on the recent attempts to examine the impact of CNPs, pro and cons on biogas production while using a metal oxide, zero-valent metals, and nano-carbon materials. The traditional view of binding CNPs to living organisms and the current view of mechanisms for improving aerobic digestive performance with metal CNPs. Furthermore, the effect of the physical parameter and kinetic limitations has discussed by the mathematical modeling that essential to observe, optimize simulate, and predict the behavior of microbes at different conditions in the AD process. Later the methanogenic activity and chemical content inhibition of CNPs on the AD system was discussed. Finally, future prospects and other recommendations discussed as conclusive remarks, which help in the substantial use of CNPs to the AD process