Weicheng Fan

Preparation and thermal properties of ABS/montmorillonite nanocomposite

Acrylonitrile-butadiene-styrene (ABS)/clay nanocomposite (nanoABS) has been prepared using a direct melt intercalation technique. Its structure and thermal properties are characterized by XRD, HTEM and TGA. The results of HTEM show that nanoABS is a kind of intercalated-delaminated structure. The nanocomposite enhances the formation of char and improves the thermal stability of ABS matrix as measured by TGA.

Preparation and thermal stability of polypropylene/montmorillonite nanocomposites

Two different methods were used to prepare polypropylene/clay nanocomposites. One was from pristine montmorillonite and a reactive compatibilizer hexadecyl trimethyl ammonium bromide (C6); the other is from different organophilic montmorillonites (OMT). The nanocomposites structures are demonstrated by X-ray diffraction (XRD) and transmission electron microscopy (TEM); The thermal properties of the nanocomposites were investigated by thermogravimetric analysis (TGA). It is shown that different methods and organophilic montmorillonites influence the morphology and thermal stability of polypropylene/clay nanocomposites.

Kinetic modeling of thermal decomposition of natural cellulosic materials in air atmosphere

Abstract The wood and leaf samples of eight species are examined by non-isothermal means to determine the mass loss kinetics of the thermal decomposition with linear temperature programming in air atmosphere. A simple kinetic description, named in this work as ‘First Order Pseudo Bi-component Separate-stage Model (PBSM-O1)’, is developed based on the experimental results and integral analysis method. The model assumes that the mass loss process of any wood or leaf sample consists of three steps. The first step corresponds to the water evaporation, and the subsequent two mass loss steps are mainly due to two major pseudo components. The two pseudo components decompose respectively at two separate temperature regions, other than at the global temperature region as used in the previous developed models by other authors. The global mass loss rate of the sample is looked on as controlled respectively by the reactions of the two components respectively during the lower and higher temperature ranges. The kinetics of the two components are found to abide by the first order equation, which gives the best fits to the experimental data compared with other model functions. The advantages of PBSM-O1 are discussed by comparing it with other kinetic models. PBSM-O1 is additionally validated by the reasonable agreement between the experimental and calculated results.

Synthesis and characterization of polycarbonate/ABS/montmorillonite nanocomposites

Abstract Polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) polymer alloy/montmorillonite (MMT) nanocomposites have been prepared by direct melt intercalation. Their structure and thermal properties are characterized by XRD, TEM, HREM and TGA. The results of XRD and HREM show that nanocomposite is a kind of intercalated structure and the gallery heights of PC/ABS/MMT nanocomposites are almost the same as that of PC/MMT nanocomposite, 3 nm; meanwhile, the nanocomposites improves the thermal stability of PC/ABS polymer alloy matrix.

Thermal analysis of poly(vinyl alcohol)/graphite oxide intercalated composites

Poly(vinyl alcohol)/graphite oxide intercalated nanocomposites have been prepared and characterized by X-ray diffraction. Their differential scanning calorimetry and thermogravimetry results suggest that the content of graphite oxide change the glass transition temperature of nanocomposites, and the increase of graphite oxide content can cause the increase of the oxidation temperature of nanocomposites and decrease of their mass loss rate.

Preparation and flammability of ethylene-vinyl acetate copolymer/montmorillonite nanocomposites

Abstract Ethylene-vinyl acetate copolymer (EVA)/montmorillonite (MMT) nanocomposites have been prepared using direct melt intercalation by blending EVA and pristine MMT with two different particle sizes: MMTa (average size 38 μm) and MMTb (average size 48 μm). Their structures and flammability properties were characterized by X-ray diffraction (XRD), high resolution electron microscopy (HREM) and Cone Calorimetry. XRD and HREM show that an intercalated structure is formed. The heat release rate (HRR) of the nanocomposite is 40% lower than that of pure EVA and 34% lower than that of the microcomposite. The microcomposite behaves very similarly to the pure EVA. The HRR of nanocomposite loaded with 5% MMTa is lower than that of the nanocomposite loaded with 5% MMTb

Preparation and flammability properties of polyethylene/clay nanocomposites by melt intercalation method from Na + montmorillonite

Abstract Polyethylene (PE)/clay composites have been prepared by melt intercalation technique direct from Na + montmorillonite (MMT) while using hexadecyl trimethyl ammonium bromide (C16) as reactive compatibilizer. Their degree of dispersion and intercalation spacings, as determined by X-ray diffraction (XRD), were typical of either a microcomposite or an intercalated nanocomposite, depending on the content of C16 in composites. Combustion experiments showed that the microcomposite burns in the same way as pure PE, whereas the heat release rate (HRR) is reduced by 32% when nanocomposite is with low silicate loading (5 wt.%) and C16 loading (4 wt.%).

An analytical evaluation of flammability limits of gaseous mixtures of combustible–oxidizer–diluent

Abstract This paper is aimed at the creation of new methods for the analytical evaluation of flammability limits of ternary gaseous mixtures of combustible–oxidizer–diluent. The physical nature of flammability limits is considered using some peculiarities of the chemical kinetics of combustion of gaseous organic substances in air. New features of lower flammability limits and compositions of mixtures near peak points of flammability curves are revealed. These features are the following. Firstly, adiabatic flame temperatures, Tad,CO, of combustion of gaseous mixtures up to CO and H2O for mixtures of fuel–air at lower flammability limits and mixtures of fuel–air–diluent at peak points of flammability curves are in rather narrow ranges. Secondly, compositions of ternary gaseous mixtures of fuel–air–diluent are close to stoichiometric in relation to combustion up to CO and H2O. It was found that such parameters as adiabatic flame temperature, Tad,CO, and equivalence ratio in relation to combustion up to CO and H2O are important for evaluation of flammability limits in ternary gaseous mixtures. New analytical methods for the calculation of flammability limits in mixtures of combustible–oxidizer–diluent are proposed, which have acceptable accuracy for practical applications.

Preparation and characterization of polystyrene/graphite oxide nanocomposite by emulsion polymerization

Polystyrene intercalated graphite oxide (GO) nanocomposite was prepared by emulsion polymerization reaction and characterized by X-ray diffraction (XRD), high resolution electron microscopy (HREM), and thermogravimetric analysis (TGA). It was shown that polystyrene can be intercalated into the interlayer space of GO and form exfoliated and intercalated nanocomposites. The thermal analysis demonstrated that the presence of GO enhances the char residue of the nanocomposite.

Preparation of the poly(vinyl alcohol)/layered double hydroxide nanocomposite

Intercalated nanocomposite based on Mg, Al layered double hydroxide (LDH) and poly(vinyl alcohol) (PVA) was prepared using exfoliation-adsorption technique, and characterized by X-ray diffraction and thermal gravimetric analysis. The results suggest that the intercalated species are formed via the re-aggregation of the delaminated LDH lamellar with the interlayer spacing 14.5 A, and the thermal stability of the nanocomposite improved compared with the original PVA.