Satya B. Sastri

Bio: Satya B. Sastri is an academic researcher from United States Naval Research Laboratory. The author has contributed to research in topics: Phthalonitrile & Thermosetting polymer. The author has an hindex of 7, co-authored 7 publications receiving 618 citations.

Phthalonitrile-carbon fiber composites

Abstract: Phthalonitrile polymers offer promise as matrix materials for advanced composite applications. The phthalonitrile monomer is readily converted to a highly crosslinked thermosetting polymer in the presence of thermally stable organic amine catalysts. Rheometric studies were conducted to elucidate the optimum amine concentration for composite formulations. High quality composite panels were processed in an autoclave using unsized IM7 carbon fibers. Mechanical properties of the phthalonitrile/carbon composite are either better than or comparable to the state-of-the-art PMR-15 composites. Dynamic mechanical analysis reveal that samples postcured at elevated temperatures (375°C) do not exhibit a glass transition temperature up to 450°C and also retain ∼90% of their initial modulus at 450°C. Flame resistance of phthalonitrile/carbon composites, evaluated by cone calorimetric studies, excels over that of other polymeric composites for marine applications. The composites also show low water uptake, <1% after exposure to water for 16 months.

Phthalonitrile cure reaction with aromatic diamines

Abstract: Phthalonitrile monomers can be polymerized thermally in the presence of small amounts of curing agents into thermosetting polymers. The thermosets exhibit outstanding thermo-oxidative stability, display good mechanical properties, and offer promise as matrices for composite applications. The phthalonitrile cure reaction is typically accomplished with an aromatic diamine, 1,3-bis(3-aminophenoxy)benzene (m-APB), added in the range of 1.5–2% by weight of the monomer in the melt phase. This article addresses the cure reaction with a sulfone-containing diamine, bis[4-(4-aminophenoxy)phenyl] sulfone (p-BAPS), which shows lower volatility as determined from thermogravimetric studies (TGA) compared to m-APB at the processing temperatures typically employed for phthalonitrile cures. Rheometric studies conducted to monitor the viscosity increase during a cure reaction suggest that the cure reaction with m-APB is faster compared to the reaction with p-BAPS. Even though differences are seen in the initial cure rates, the final cured products are similar in terms of the glass transition temperatures and thermal and oxidative stabilities. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1885–1890, 1998

Phthalonitrile polymers: Cure behavior and properties

Abstract: This article compares the cure behavior and properties of phthalonitrile polymers derived from three different monomers, namely, 4,4′-bis(3,4-dicyanophenoxy)biphenyl, 2,2-bis[4-(3,4-dicyanophenoxy)phenyl]hexafluoropropane and 2,2-bis[4-(3,4-dicyanophenoxy)phenyl]propane. Rheometric measurements with monomer melt in the presence of an aromatic diamine curing agent reveal that the rate of the cure reaction differs for the three monomers. The rate is dependent on the concentration of the curing agent. The glass transition temperature advances with increasing extent of cure and disappears upon postcure at temperatures in excess of 350°C. Based on thermogravimetric analysis, the thermal stability of all three polymers are comparable, whereas the fluorine-containing resin shows the best oxidative stability at elevated temperatures. Microscale calorimetric studies on all three polymers reveal that the char yields are high and the total heat release upon exposure to 50 kW/m2 flux for each polymer is low, compared to other thermosets. Flexural strength ranges between 80–120 MPa. The water uptake under ambient conditions is less than 3% by weight after submersion in water for seven months. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2105–2111, 1999

Phthalonitrile‐glass fabric composites

Abstract: Phthalonitrile polymers, under development at the Naval Research Laboratory, offer promise as high temperature, high performance composite matrix materials. A fully cured resin shows outstanding thermal stability with no evidence of a glass transition temperature or T g up to 450°C, good mechanical properties, and is easily processed into void-free components. Phthalonitrile/glass fabric composite panels have been successfully fabricated by conventional consolidation of prepregged glass and by a more recently developed simplified process, resin infusion molding. Both processes can be used to produce panels with comparable mechanical properties. More important, flammability performance of these composites, evaluated in terms of specific optical density, combustion gases, heat release, and ignitability, excels over other state-of-the-art polymer/glass composites. This finding is significant given that overcoming flammability obstacles has been the main limiting factor for use of composites in marine applications.

Fire Properties of Polymer Composite Materials

Abstract: Preface 1 Introduction: 1.1 Background 1.2 Fire reaction and fire resistive properties of composites 1.3 Composites and fire 1.4 Case studies of composites in fire 1.5 Concluding remarks References 2Thermal Decomposition of Composites in Fire: 2.1 Introduction2.2. Thermal decomposition mechanisms of organic polymers 2/3 Rate processes and characterisation of decomposition 2.4 Polymers and their decomposition processes 2.5 Fire damage to composites 2.6 Concluding remarks References 3 Fire Reaction Properties of Composites: 3.1 Introduction 3.2 Time-to-ignition 3.3 Heat release rate 3.4 Extinction flammability index & thermal stability index 3.5 Mass loss 3.6 Smoke 3.7 Smoke toxicity 3.8 Limiting oxygen index 3.9 Surface spread of flame 3.10 Fire resistance References 4. Fire Modelling of Composites: 4.1 Introduction 4.2 Thermal exposure 4.3 Modelling material fire dynamics 4.4 Structural modelling of fire response References 5 Modelling the Thermal Response of Composites in Fire: 5.1 Introduction 5.2 Response of composites to fire 5.3 Modelling heat conduction in composites 5.4 Modelling the fire response of composites 5.5 Modelling the thermal properties of composites 5.6 Concluding remarks References 6. Structural Properties of Composites in Fire: 6.1 Introduction 6.2 Laminate properties 6.3 Measurement of elastic constants 6.4 Mechanical properties as a function of temperature 6.5 Modelling of properties 6.6 Fire resistance of laminates under load 6.7 Modelling of fire resistance of laminates under load 6.8 Concluding remarks References 7. Post-Fire Properties of Composites: 7.1 Introduction 7.2 Post-fire properties of laminates 7.3 Modelling the post-fire properties of laminates 7.4 Post-fire properties of sandwich composites 7.5 Post-fire properties of fire protected composites 7.6 Concluding remarks References 8 Flame Retardant Composites: 8.1 Introduction 8.2 The combustion cycle 8.3 Flame retardants for composites 8.4 Flame retardant fillers for composite 8.5 Flame retardant organic polymers for composites 8.6 Flame retardant inorganic polymers for composites 8.7 Flame retardant fibres for composites 8.8 Fire protective surface coatings References 9 Fire Properties of Polymer Nanocomposites: 9.1 Introduction 9.2 Characterization of nanocomposite formation 9.3 Evaluation of fire retardancy 9.4 Clay modifications 9.5 Examples of fire retardancy of polymer nanocomposites 9.6 Mechanisms of fire retardancy in nanocomposites 9.7 Future trends in fire retardancy of nanocomposites References 10 Fire Safety Regulations: 10.1 Introduction 10.2 Fire safety regulations for rail 10.3 Fire safety regulations for automobiles, buses and trucks 10.4 Fire safety regulations for civil infrastructure 10.5 Fire safety regulations for civilian aircraft 10.6 Fire safety regulations for ships and submarines References 11 Fire Tests for Composites: 11.1 Introduction 11.2 Scale of fire reaction tests 11.3 Cone calorimeter 11.4 Atmosphere controlled cone calorimeter 11.5 Intermediate-scale cone calorimeter 11.6 Ohio State University calorimeter 11.7 Limiting oxygen index test 11.8 Flame spread tests 11.9 Smoke density tests 11.10 Furnace tests 11.11 Burn-through & jet-fire tests 11.12 Single burning item test 11.13 Room fire tests 11.14 Structural integrity in fire tests 11.15 Aircraft fire tests 11.16 Concluding remarks References 12 Health Hazards of Composites in Fire: 12.1 Introduction 12.2 Smoke toxicity test methods 12.3 Health hazards of combustion gases 12.4 N-gas model for smoke toxic potency 12.5 Health hazards of fibres 12.6 Personal protective wear against burning composite materials 12.7 Concluding remarks References Subject Index

Review of fire structural modelling of polymer composites

Abstract: This paper presents a critical review of research progress in modelling the structural response of polymer matrix composites exposed to fire. Models for analysing the thermal, chemical, physical, and failure processes that control the structural responses of laminates and sandwich composite materials in fire are reviewed. Models for calculating the residual structural properties of composites following fire are also described. Progress towards validation of the models by experimental characterisation of the structural properties of composites during and following fire is assessed. Deficiencies in the fire structural models are identified in the paper, which provide the focus for future research in the field.