Charles A. Wilkie

Flame retardant polymer nanocomposites

Preface. Acronyms. 1 Introduction to Flame Retardancy and Polymer Flammability (Sergei V. Levchik). 1.1 Introduction. 1.2 Polymer Combustion and Testing. 1.3 Flame Retardancy. 1.4 Conclusions and Future Outlook. References. 2 Fundamentals of Polymer Nanocomposite Technology (E. Manias, G. Polizos, H. Nakajima, and M. J. Heidecker). 2.1 Introduction. 2.2 Fundamentals of Polymer Nanocomposites. 2.3 Effects of Nanofillers on Material Properties. 2.4 Future Outlook. References. 3 Flame Retardant Mechanism of Polymer-Clay Nanocomposites (Jeffrey W. Gilman). 3.1 Introduction. 3.2 Flame Retardant Mechanism. 3.3 Conclusions and Future Outlook. References. 4 Molecular Mechanics Calculations of the Thermodynamic Stabilities of Polymer-Carbon Nanotube Composites (Stanislav I. Stoliarov and Marc R. Nyden). 4.1 Introduction. 4.2 Background and Context. 4.3 Description of the Method. 4.4 Application to PS-CNT Composites. 4.5 Uncertainties and Limitations. 4.6 Summary and Conclusions. References. 5 Considerations Regarding Specific Impacts of the Principal Fire Retardancy Mechanisms in Nanocomposites (Bernhard Schartel). 5.1 Introduction. 5.2 Influence of Nanostructured Morphology. 5.3 Fire Retardancy Effects and Their Impact on the Fire Behavior of Nanocomposites. 5.4 Assessment of Fire Retardancy. 5.5 Summary and Conclusions. References. 6 Intumescence and Nanocomposites: a Novel Route for Flame-Retarding Polymeric Materials (Serge Bourbigot and Sophie Duquesne). 6.1 Introduction. 6.2 Basics of Intumescence. 6.3 Zeolites as Synergistic Agents in Intumescent Systems. 6.4 Intumescents in Polymer Nanocomposites. 6.5 Nanofillers as Synergists in Intumescent Systems. 6.6 Critical Overview of Recent Advances. 6.7 Summary and Conclusion. References. 7 Flame Retardant Properties of Organoclays and Carbon Nanotubes and Their Combinations with Alumina Trihydrate (Gunter Beyer). 7.1 Introduction. 7.2 Experimental Process. 7.3 Organoclay Nanocomposites. 7.4 Carbon Nanotube Nanocomposites. 7.5 Summary and Conclusions. References. 8 Nanocomposites with Halogen and Nonintumescent Phosphorus Flame Retardant Additives (Yuan Hu and Lei Song). 8.1 Introduction. 8.2 Preparation Methods and Morphological Study. 8.3 Thermal Stability. 8.4 Mechanical Properties. 8.5 Flammability Properties. 8.6 Flame Retardant Mechanism. 8.7 Summary and Conclusions. References. 9 Thermoset Fire Retardant Nanocomposites (Mauro Zammarano). 9.1 Introduction. 9.2 Clays. 9.3 Thermoset Nanocomposites. 9.4 Epoxy Nanocomposites Based on Cationic Clays. 9.5 Epoxy Nanocomposites Based on Anionic Clays. 9.6 Polyurethane Nanocomposites. 9.7 Vinyl Ester Nanocomposites. 9.8 Summary and Conclusions. References. 10 Progress in Flammability Studies of Nanocomposites with New Types of Nanoparticles (Takashi Kashiwagi). 10.1 Introduction. 10.2 Nanoscale Oxide-Based Nanocomposites. 10.3 Carbon-Based Nanocomposites. 10.4 Discussion of Results. 10.5 Summary and Conclusions. References. 11 Potential Applications of Nanocomposites for Flame Retardancy (A. Richard Horrocks and Baljinder K. Kandola). 11.1 Introduction. 11.2 Requirements for Nanocomposite System Applications. 11.3 Potential Application Areas. 11.4 Future Outlook. References. 12 Practical Issues and Future Trends in Polymer Nanocomposite Flammability Research (Alexander B. Morgan and Charles A. Wilkie). 12.1 Introduction. 12.2 Polymer Nanocomposite Structure and Dispersion. 12.3 Polymer Nanocomposite Analysis. 12.4 Changing Fire and Environmental Regulations. 12.5 Current Environmental Health and Safety Status for Nanoparticles. 12.6 Commercialization Hurdles. 12.7 Fundamentals of Polymer Nanocomposite Flammability. 12.8 Future Outlook. References. Index.

Preparation of graphene by pressurized oxidation and multiplex reduction and its polymer nanocomposites by masterbatch-based melt blending

Graphene is prepared from graphite by pressurized oxidation and multiplex reduction. The pressurized oxidation is advantageous in easy operation and size-control, and the multiplex reduction, based on ammonia and hydrazine, produces single-atom-thick graphene (0.4–0.6 nm thick) which can be directly observed by atomic force microscopy. A masterbatch strategy, which is feasible in “soluble” thermoplastic polymers, is developed to disperse graphene into poly(lactic acid) by melt blending. The graphene is well dispersed and the obtained nanocomposites present markedly improved crystallinity, rate of crystallization, mechanical properties, electrical conductivity and fire resistance. The properties are dependent on the dispersion and loading content of graphene, showing percolation threshold at 0.08 wt%. Graphene reinforces the nanocomposites but cuts down the interactions among the polymer matrix, which leads to reduced mechanical properties. Competition of the reinforcing and the reducing causes inflexions around the percolation threshold. The roles of the heat barrier and mass barrier effects of graphene in the thermal degradation and combustion properties of the nanocomposites are discussed and clarified.

Thermal and fire studies on polystyrene–clay nanocomposites

Nanocomposites of polystyrene and several organophilic clays have been prepared by a bulk polymerization technique. The resulting polymers have an intercalated structure and show enhanced thermal stability, as measured by thermogravimetric analysis and cone calorimetry, relative to virgin polystyrene, even when as little as 0.1% of clay has been added.

Thermal stability and flame retardancy of poly(methyl methacrylate)-clay nanocomposites

Abstract Three ammonium salts, hexadecylallyldimethyl ammonium chloride (Allyl16), hexadecylvinylbenzyldimethyl ammonium chloride (VB16) and hexadecylvinylbenzyldimethyl ammonium chloride (Bz16) were synthesized and ion exchanged onto montmorillonite. Poly(methyl methacrylate)–clay nanocomposites of all three clays were prepared by bulk polymerization and the resulting nanocomposites were characterized by X-ray diffraction and transmission electron microscopy. The clays which contain a pendant double bond are more likely to give an exfoliated material while that which contains no double bond is intercalated. The thermal stability and flame retardancy were measured by thermogravimetric analysis (TGA) and Cone Calorimetry respectively.

Effect of MgAl-layered double hydroxide exchanged with linear alkyl carboxylates on fire-retardancy of PMMA and PS

Alkyl carboxylate-modified layered double hydroxides (LDH) were prepared and used as nanofillers for poly(methyl methacrylate) (PMMA) and polystyrene (PS). The LDH intercalated with long-chain linear alkyl carboxylates (CH3(CH2)nCOO−, n = 8, 10, 12, 14, 16, 20) were prepared via anionic exchange of MgAl–nitrate, showing a systematic increase in basal spacing with longer alkyls. MgAl–undecenoate LDH was prepared by co-precipitation. The MgAl–LDHs were melt blended with poly(methyl methacrylate) and bulk polymerized with styrene to form nanocomposites. The dispersion of the MgAl–LDH in the polymers was investigated by transmission electron microscopy and X-ray diffraction. Thermal and fire properties were studied using cone calorimetry and thermogravimetric analysis; the thermal stability of both polymers was enhanced and a very significant reduction in the peak heat release rate was observed for almost all of the poly(methyl methacrylate) composites and a few of the polystyrene composites.

Preparation and flammability properties of polyethylene-clay nanocomposites

Abstract Polyethylene (PE)–clay nanocomposites have been prepared using melt blending in a Brabrender mixer. X-ray diffraction and transmission electron microscopy were used to characterize the nano-structure of these composites while the thermal stability was evaluated from thermogravimetric analysis and the flammability parameters using cone calorimetry. It is found that the PE–clay nanocomposites have a mixed immiscible-intercalated structure and there is better intercalation when maleic anhydride is combined with the polymer and clay to be melt blended. The reduction in peak heat release rate is 30–40%.

Photo-oxidation of polymeric-inorganic nanocomposites: chemical, thermal stability and fire retardancy investigations

Nanocomposites of polypropylene-graft-maleic anhydride/clay and polypropylene/clay were prepared by melt blending using two different approaches. X-Ray diffraction results showed an intercalated structure. Samples of nanocomposites were exposed to UV light under atmospheric oxygen and their photo-oxidative stability was studied using FTIR and UV spectroscopy. The consequences of this photo-oxidation on the thermal stability and fire retardant performance of the nanocomposites were also addressed from thermogravimetry analysis and Cone calorimetry.

The Thermal Degradation of Polyacrylonitrile

The volatile products that are evolved during the thermolysis of polyacrylonitrile have been studied by TGA/FTIR techniques. The complementary solid products that are not volatile have also been isolated and characterized, by means of elemental analysis and infra-red spectroscopy. Cyclization of the polymer proceeds before any mass is lost and the driving force for cyclization is the formation of aromatic rings. The extent of cyclization is controlled by the presence of head-to-head linkages within the polymer. Ammonia and hydrogen cyanide are the first gases lost and schemes are proposed to account for their formation. Oligomers are lost from the uncyclized portion of the polymer lying between the cyclized portions and the amount of non-volatile fraction is largely determined by the extent of oligomer loss. A detailed mechanism is presented to account for the observed formation of the volatile products and the structural changes that occur in the residue.

TGA/FTIR studies on the thermal degradation of some polymeric sulfonic and phosphonic acids and their sodium salts

The thermal degradation of poly(vinyl sulfonic acid) and its sodium salt, poly(4-styrenesulfonic acid) and its sodium salt, and poly(vinylphosphonic acid) was studied by a combination of techniques, including TGA/FTIR, to identify the volatile products which were evolved during the degradation as well as analysis of the residues which were obtained in order to propose a mechanism for the degradation. The motivation for the work was to attempt to identify new monomers which could be graft copolymerized onto a polymer in order to improve the thermal stability of that polymer.

The thermal degradation of acrylonitrile-butadiene-styrene terpolymei as studied by TGA/FTIR

Abstract The thermal degradation of acrylonitrile-butadiene-styrene (ABS) terpolymer has been studied by TGA/FTIR. The degradation of ABS is compared with that of polystyrene, polybutadiene, polyacrylonitrile (PAN), and styreneacrylonitrile (SAN) copolymer. A small amount of acrylonitrile monomer is eliminated from PAN, SAN, and ABS. The grafting of butadiene on to SAN stabilizes the butadiene structure, since the evolution of butadiene begins 50 °C higher than in the homopolymer. The evolution of aromatics begins about 20 °C lower in ABS than in SAN, so the presence of the butadiene destabilizes SAN. The evolution of acrylonitrile begins at essentially the same temperature in ABS as in SAN. There are some significant effects on the degradation produced by grafting SAN onto polybutadiene but the degradation may be understood by considering the degradation of its components.