ICTAC Kinetics Committee recommendations for performing kinetic computations on thermal analysis data

Structural engineering of polyurethane coatings for high performance applications

Recent developments in the chemistry of halogen-free flame retardant polymers

Thermal stability and flame retardancy of polyurethanes

Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

The study reports the variation in acoustic emission signals acquired during combustion of typical propellants with varying aluminium and ammonium perchlorate content. It was observed that when propellant strands having the same composition undergo combustion under similar conditions, they produce consistent acoustic emission signals. To study the effect of variation of aluminium content in the propellant composition on the acoustic emission produced during combustion, the aluminium content was varied from 6 per cent to 18 per cent in a HTPB-based composite propellant with 86 per cent solid loading. Experiments were carried out with propellant strands under the same conditions for a comparative study. Acoustic emission parameters, such as peak amplitude, ring-down counts, average frequency, hits and energy were studied as functions of time. Among these parameters, only energy ring-down counts and frequency varied significantly with aluminium content. The effect of cumulative values of energy, frequency and ring-down counts, the effect of burn rate and theoretical specific impulse against the aluminium percentage variation, and the variation of specific impulse against acoustic energy can all be correlated. The clear trend is indicative of possible prediction of propellant performance parameter like specific impulse from acoustic emission parameters.

Effect of aluminium in propellant composition on acoustic emission parameters (Short Communication)

Styrene-butadiene rubber/natural rubber blend membranes were prepared by conventional vulcanization technique. The morphology of styrene-butadiene rubber/natural rubber blend membranes has been investigated by combining scanning electron microscopy with measurements of permeability to chlorinated hydrocarbon vapours. The results obtained from both SEM and permeation measurements suggest that SBR/NR blend membranes are heterophase in nature. The effect of structure of the penetrant on permeation through blend membranes was also investigated. Finally, the permeation of chlorohydrocarbon vapours through membranes is compared with permeation of oxygen and nitrogen gases through the membranes.

Permeation of Chlorinated Hydrocarbons Through Styrene-Butadiene Rubber/Natural Rubber Blends

The properties of the ternary matrix system (EPB), obtained by the reactive blending of epoxy resin - diallyl bisphenol and a bismaleimide, depend on the structure and properties of its components....

Bismaleimide Modified Epoxy-Diallylbisphenol System – Effect of Bismaleimide Nature on Properties:

The ternary matrix system comprising a reactive blend of epoxy, diallylbisphenolA, and bisphenolAbismaleimide (EPB) was found to be comparable with the epoxy-phenol (EP) system in terms of its mechanical properties, and superiorto it in terms of its high-temperature performance. The influence of structural variations of the epoxy resin on the thermal, physical, and mechanical properties of the ternary blend was examined. EPB compositions were prepared using a combination ofbisphenolAbismaleimide and diallylbisphenolA with three different epoxy resin systems, namely novolac epoxy (El), bisphenol A diglycidyl ether (E2), and tris(4-glycidyloxyphenyl)methane (E3). Cure characterisation of these reactive blends (EPB-E1, EPB-E2 and EPB-E3) was carried out using IR spectroscopy, differential scanning calorimetry, and rheological analysis. The trend in their thermal stability, based on the temperature of the onset of decomposition, is EPB-E3 > EPB-E1 > EPB-E2. The mechanical properties - compressive, flexural, and interlaminar shear strength - of the glass composites of these matrices were found to depend on the epoxy structure. The higher crosslink density of the trifunctional epoxy improved the high-temperature properties of the system. The ternary system served as a very good adhesive, where its strength as well as its retention at high temperature increased in proportion to the functionality of the resin. In general, the maximum strength values were observed for the system containing the novolac epoxy.

Influence of Epoxy Nature on the Properties of an Epoxy-Diallylbisphenol A-Bismaleimide Matrix System

Traditional systems of accounting for agricultural productivity focus solely on yield-based contributions and totally ignore the biodiversity and ecosystem services derived from agriculture. The study uses a framework and approaches developed under ‘The Economics of Ecosystems and Biodiversity (TEEB) AgriFood ‘initiative to demonstrate the hidden values of Agri-systems through valuation of agro-ecological elements using subsidies for hidden costs and incentivizing unaccounted benefits. These unaccounted benefits could be monetized through policy and economic instruments to supplement farmers’ income. The paper recommends a mix of policy and fiscal interventions such as Payment for Ecosystem Services (PES) or Remuneration of Positive Externalities (RPE), tax rebates, and subsidies which can promote sustainable agricultural practices.

K. N. Ninan

Papers

Effect of aluminium in propellant composition on acoustic emission parameters (Short Communication)

Permeation of Chlorinated Hydrocarbons Through Styrene-Butadiene Rubber/Natural Rubber Blends

Bismaleimide Modified Epoxy-Diallylbisphenol System – Effect of Bismaleimide Nature on Properties:

Influence of Epoxy Nature on the Properties of an Epoxy-Diallylbisphenol A-Bismaleimide Matrix System

Transforming the Yardstick Used to Measure Benefits From the Farm Sector