Zhengzhou Wang

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.

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.

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.%).

Halogen-free flame retardation and silane crosslinking of polyethylenes

Halogen-free flame-retarded and silane crosslinkable polyethylenes have been prepared by a melt process using magnesium hydroxide (MH) as a flame retardant. The effects of silane concentration, peroxide concentration, etc. on the silane grafting on linear low density polyethylenes were investigated. The thermal analysis of the silane crosslinked polyethylenes was performed by thermogravimetry (TG), and its results show that silane crosslinking provides an increase in the thermal stability of polyethylenes. The combustion characteristics of the silane crosslinked polyethylenes containing MH have also been studied using limiting oxygen index (LOI) and the Cone Calorimeter. The rate of heat release and smoke emission of the silane crosslinked polyethylenes decrease, and LOI, the time to ignition and the residue after combustion increase as MH content increases.

Intumescent Flame Retardation of EVA Using Microencapsulated Ammonium Polyphosphate and Pentaerythritols

With a melamine-formaldehyde (MF) resin coating layer, microencapsulated ammonium polyphosphate (MCAPP) is prepared by in situ polymerization and is characterized by XPS and water leaching test. The microencapsulation of APP with the MF resin leads to a decrease in the particles water leaching rate. The flame-retardant action of MCAPP and APP in EVA are studied using LOI and UL 94 test, and their thermal stability is evaluated by thermogravimetric analysis (TGA). The LOI value of the EVA/MCAPP composite at the same loading is higher than the value of the EVA/APP composite. In comparison with the EVA/MCAPP composites, it is found that the LOI values of the EVA/MCAPP/PER and EVA/MCAPP/DPER ternary composites at the same additive loading increase, and UL 94 ratings of most ternary composites are raised to V-0. The water-resistant properties of the EVA composites are studied, and the results of the composites containing with APP and MCAPP are compared. Moreover, the peroxide cross-linking of the EVA composites is investigated, and the mechanical properties and thermal stability of the composites increase after the cross-linking.

Preparation and Characterization of Core/Shell-like Intumescent Flame Retardant and its Application in Polypropylene

With a shell of starch-melamine-formaldehyde (SMF) resin, core/shell-like ammonium polyphosphate (SMFAPP) is prepared by in situ polymerization, and is characterized by SEM, FTIR and XPS. The shell leads SMFAPP a high water resistance and flame retardance compared with APP in polypropylene (PP). The flame retardant action of SMFAPP and APP in PP are studied using LOI, UL 94 test and cone calorimeter, and their thermal stability is evaluated by TG. The flame retardancy and water resistance of the PP/SMFAPP composite at the same loading is better than that of the PP/APP composite. UL 94 ratings of PP/SMFAPP can reach V-0 at 30 wt% loading. The flame retardant mechanism of SMFAPP was studied by dynamic FTIR, TG and cone calorimeter, etc.

Microencapsulated Ammonium Polyphosphate with Polyurethane Shell: Application to Flame Retarded Polypropylene/Ethylene-propylene Diene Terpolymer Blends

Microencapsulated ammonium polyphosphate with polyurethane resin (PUMAPP) was prepared by in situ polymerization and characterized by X-ray photoelectron spectroscopy (XPS). The flame retardation of PUMAPP/dipentaerythritol(DPER) and ammonium polyphosphate (APP)/DPER flame retarded polypropylene (PP)/ethylene propylene diene rubber (EPDM) composites were studied using limiting oxygen index (LOI), UL-94 test and cone calorimeter. Results demonstrated that the flame retardancy of the PP/EPDM/PUMAPP/DPER composites was better than that of the PP/EPDM/APP/DPER composites at the same additive loading. Real time Fourier transform infrared (FTIR) and thermogravimetric analysis (TG) were used to study the thermal degradation and stability of the PP/EPDM/PUMAPP/DPER composite. The hydrolytic stability of the flame retarded PP/EPDM composites was studied. It was found that the microencapsulation of APP with the PU resin leaded to a decrease in the particles water solubility. Moreover, the synergistic effect of vinyltrimethoxysilane (VTMS) on the PP/EPDM/PUMAPP/DPER composite was also investigated.

Flammability and Thermo-Oxidative Decomposition of Epoxy Resin Containing Ammonium Polyphosphate and Metallic Oxide

Cured epoxy resin (EP) composites containing Ammonium Polyphosphate (APP) and metallic oxide were prepared and characterized. The flame retardancy of the composites was studied using LOI, UL 94, cone calorimeter and Laser Raman spectroscopy, etc. The data of LOI, UL 94 and cone calorimeter show that APP is a good flame retardant for EP. The LOI value of the composite containing 20 wt% APP is as high as 38.0% and its UL 94 rating is raised to V-0. The addition of APP and La2O3 leads to the formation of char layer containing smaller carbonaceous microstructures compared with that of EP. Moreover, the thermo-oxidative decomposition of EP and its composites is characterized by dynamic FTIR.

Preparation of a silica nanospheres/graphene oxide hybrid and its application in phenolic foams with improved mechanical strengths, friability and flame retardancy

A silica nanospheres/graphene oxide (SGO) hybrid was successfully synthesized through immobilization of silica (SiO2) nanospheres on the surface of graphene oxide (GO) sheets, and characterized by X-ray diffraction (XRD), field emission scan electronic microscopy (FESEM) and transmission electronic microscopy (TEM). It has been found that the incorporation of the SGO into the phenolic (PF) foams not only obviously increases the mechanical strengths and flame retardancy, but also reduces the pulverization ratio. Specifically, the flexural and compressive strengths of the PF foam modified by 1.5 phr SGO increases by 31.6% and by 36.2%, respectively, compared with pure PF foam. The Cone calorimetric results indicate that the addition of SGO into PF foam leads to a reduction in peak heat release rate and total heat release. Moreover, the thermal stability of the PF foams containing SGO is enhanced compared with the pure PF foam.

One-step in situ synthesis of a novel α-zirconium phosphate/graphene oxide hybrid and its application in phenolic foam with enhanced mechanical strength, flame retardancy and thermal stability

A novel α-zirconium phosphate/graphene oxide hybrid (ZGO) with α-zirconium phosphate (α-ZrP) nanoparticles immobilized on the surface of graphene oxide (GO) sheets was successfully synthesized by a one-step in situ method, and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), FTIR spectroscopy and transmission electronic microscopy (TEM). TGA results showed that the modification of α-ZrP nanoparticles on the GO surface significantly improved the thermal stability of the GO. Subsequently, the ZGO was incorporated into phenolic (PF) foams for reducing their high brittleness and friability. At a ZGO dosage of 4 phr (parts per hundreds of resin), the flexural and compressive strengths of the ZGO-toughened PF foams increased by 33.8% and by 39.6%, respectively, and the pulverization ratio decreased by 57.5%, compared with the pure PF foam. Besides, the results of the TGA test, limiting oxygen index (LOI) and cone calorimetric test demonstrated that the addition of ZGO imparted excellent thermal stability and flame retardancy to the PF foam, which was mainly attributed to the synergistic effects between α-ZrP nanoparticles and GO.