Arthur Bobovitch

Thermal analysis of the polymerization process on the surface of inorganic fillers

The thermal polymerization of pentabromobenzyl (mono)acrylate (PBB-MA) on the surface of the inorganic fillers Mg(OH)2 and CaCO3 was studied. FTIR spectroscopy and extraction of the polymer in bromobenzene show that polypentabromobenzyl acrylate (PBB-PA) was mostly grafted on the surface of Mg(OH)2. Thermal analysis (TG, DSC, isothermal DSC (IDSC)) demonstrated an increase in polymerization starting temperature, and differences in polymerization enthalpy and apparent activation energy when an inorganic filler is added. These differences depend on the chemical composition of the filler used.

New approach to flame retardants: thermal polymerization on fillers

Abstract Thermal polymerization of pentabromobenzyl (mono)acrylate (PBB-MA) on the surface of magnesium hydroxide was studied with thermogravimetrical, FTIR and extraction methods. Poly (pentabromobenzyl acrylate) (PBB-PA) grafted on the surface of Mg(OH) 2 in acrylonitrile-butadiene-styrene copolymer (ABS) allowed the achievement of better properties than pure PBB-PA: higher heat distortion temperature (HDT), higher impact energy, lower smoke density.

Morphology and stress-relaxation of biaxially oriented cross-linked polyethylene films

In the present work, the morphology and stress-relaxation of cross-linked polyethylene films were investigated. The stress-relaxation of cross-linked films was studied as a function of temperature and as a function of the irradiation dose applied. The relaxation time spectra of cross-linked films were observed to display additional relaxation times. Irradiation dose and temperature were shown to influence the relaxation time spectrum of cross-linked and non-cross-linked films. The crystallization of cross-linked and non-cross-linked polyethylene was compared. It was shown that the lower mobility of the cross-linked molecules affects the final crystallinity.

Morphology, Mechanical Properties and Stress-relaxation of Biaxially Oriented Polyethylene Films Irradiated with β-radiation

The present study describes an influence of β-radiation on morphology, mechanical properties and stress-relaxation of biaxially oriented polyethylene films. The mechanical properties and stress-relaxation of irradiated crosslinked films were studied as a function of the irradiation dose applied. The relaxation time spectra of crosslinked films were observed to display additional relaxation times. Irradiation dose of 4 megarads (MR) was found to be optimal from the viewpoint of mechanical properties. The crystallization of crosslinked and noncrosslinked polyethylene was compared. It was shown that irradiation affects the final crystallinity of polyethylene. Lower crystallinity was observed due to lower mobility of crosslinked molecules.

Orientation,Structure and Properties of Double-Bubble Oriented Lldpe Films

Biaxially oriented linear low density polyethylene (LLDPE) films are produced using the double-bubble process with different machine direction (MD) orientation levels and the same transverse direction (TD) blow-up ratio. Their mechanical behavior is characterized in terms of the tensile strength and tear resistance. The microstructure and orientation are characterized using microscopy, x-ray diffraction (XRD), and Fourier transform infra red spectroscopy (FTIR). The results indicate that MD tensile strength increases with increasing MD stretching (draw) ratio while the TD tensile decreases. Tear resistance remains mainly constant in TD and decreases in MD with increases in draw ratio. Morphology analysis reveals that overstretching lamellae tend to align perpendicular to MD with an increase of their lamellar dimensions. c-axis orientation of lamellae in MD increases with draw ratio while a-and b-axes orient towards normal direction (ND) and TD respectively. A good correlation is observed between c-axis orientation and MD tear resistance and tensile strength.