Marija M. Vuksanović

Optimizing the thermal gradient and the pulling speed in a thermoplastic pultrusion process of PET/E glass fibers using finite element method

A thermoplastic pultrusion process was examined using commercial fiber roving of PET/E glass, to determine the optimum pulling speed and optimal zonal temperatures. Finite element analysis predicted heat transfer through the commingled fibers and air in the pultrusion die. The cross-section of obtained rods was examined, and image analysis was carried out to obtain information about the degree of fiber impregnation, number of voids and uniformity of fiber distribution. Optimizing the temperature field for the pultrusion of poly (ethylene terephthalate) is of significant importance. The pulling speed has the same importance. These two parameters are closely related as evidenced by the analysis of images.

The influence of alumina particle modification on the adhesion of the polyacrylate matrix composite films and the metal substrate

ABSTRACT Adhesion behavior between the composite films, consisting of UV cured Bis-GMA (Bisphenol A glycidylmethacrylate)/TEGDMA (triethylene glycol dimethacrylate) as a matrix and the ferrous oxide doped alumina particles, Al2O3 Fe, modified with 3-aminopropyl)tri – methoxysilane (AM) and methyl esters of linseed oil fatty acids (biodiesel – BD) used as a reinforcement, and metallic surface was investigated in this study. Al2O3 Fe-BD particles showed pronounced hydrophobicity and hydrolytic stability of alumina surface. Adhesive and mechanical properties of prepared composites, containing 0.5, 1.5 and 3 wt. % of surface modified Al2O3 Fe-AM and Al2O3 Fe-BD particles, were compared to the neat polymer matrix. Adhesion parameter was evaluated using the micro hardness testing method. The comparison of determined contact angle with adhesive parameter, obtained from micro hardness measurements, was discussed in relation to structural effect of reinforcement used.

Improvement of cavitation resistance of composite films using functionalized alumina particles

Composite films having the UV cured Bis-GMA (Bisphenol A glycidylmethacrylate)/TEGDMA (triethylene glycol dimethacrylate) as a matrix and the ferrous oxide doped alumina (Al2O3 Fe) based particles were prepared and subjected to cavitation. In order to improve the mechanical and adhesion properties of composites, four different surface modifications of filler particles were performed: 3-methacryloxypropyltrimethoxysilane (MEMO), vinyltris(2-methoxyethoxy)silane (VTMOEO), (3-aminopropyl)trimethoxysilane (APTMS) and biodiesel (BD). Composite films were made with 0.5, 1.5, and 3 wt.% of ferrous oxide doped alumina particles with each of the mentioned surface modifications. Composite films were prepared on brass substrates and exposed to cavitation erosion. The erosion was monitored using the mass loss while image analysis was used to observe surface defects. The composite film reinforced with Al2O3 Fe having VTMOEO as a surface modifier was the most resistant one in terms of mass loss, as well as the level of surface destruction. Results were compared to the same polymer matrix film and composite films prepared with fillers without surface modifications revealing that all composites with surface modified fillers exhibited some improvement in resistance to cavitation.