Effect of polyhedral-oligomeric-sil-sesquioxanes on thermal and mechanical behavior of SC-15 epoxy

Abstract

Abstract. In this study, thermal and mechanical properties of nanocomposites containing SC-15 epoxy resin and polyhedral-oligomeric-sil-sesquioxanes (POSS) have been studied. Dynamic Mechanical Analysis (DMA) results show that the addition of 5 wt% of POSS yielded a 13% increase in the storage modulus and a 16°C enhancement in Tg. Thermo gravimetric Analysis (TGA) results show that the thermal stability of epoxy increased with higher POSS content. Tension tests were used to evaluate the mechanical properties of materials. Both modulus and tensile strength are linear functions of POSS content. Scanning Electric Microscopy (SEM) pictures of fracture surfaces show that the roughness of the fracture surfaces of epoxy increased after adding POSS. Based on experiment results, a three-parameter nonlinear constitutive equation was developed to describe the strain-softening stress-strain relationship behavior of materials. The parameters in this model are the elastic modulus, a strain exponent, m, and a compliance factor, β. Their relationships to the POSS weight fraction were obtained from the experiment results. The simulated stress-strain curves from the model agree with the test data. Analysis of the model shows that both the strain exponent, m, which controls the strain softening and hardening effect of the material, and the compliance parameter, β, which controls the flow stress level of the material, increase with higher POSS content.

Relationships between nanostructure and dynamic-mechanical properties of epoxy network containing PMMA-modified silsesquioxane

“…Consequently an improvement of thermal, oxidative and dimensional stability as well as mechanical performance of many polymeric resins is usually achieved. Mono-and multi-functionalized silsesquioxanes containing epoxy [7,[19][20][21][22][23][24][25][26][27], amino [28][29][30][31][32], mercapto [33], maleimido [34,35], and isocyanate groups [36] have been successfully employed in the preparation of epoxy resin-based hybrid materials. Mono-functionalized silsesquioxanes are prepared by corner capping reaction of a trisilanol with a functionalized trialkoxy silane, and results in POSS molecules grafted onto the epoxy matrix [14].…”

“…Polyfunctional POSS is obtained from the hydrolysis/ condensation of a functionalized trialkoxi silane resulting in polymer networks with the POSS cage acting as a crosslinking site [7]. Epoxy resin/POSS hybrid materials are prepared by mixing both components [23] or by performing the hydrolysis/condensation of the silane precursor in the presence of the epoxy matrix. When the POSS molecule is prepared in situ, the inorganic siloxane particles are more linked with the epoxy network because the alkoxy groups of the silane precursor can react with the hydroxyl groups formed by the ring opening reaction of the epoxy groups, through an ether exchange reaction [20].…”

Phenyl hepta cyclopentyl – polyhedral oligomeric silsesquioxane (ph,hcp-POSS)/Polystyrene (PS) nanocomposites: the influence of substituents in the phenyl group on the thermal stability

“…composites [23][24][25][26][27][28][29]. The general formula of POSSs is (RSiO 1.5 ) n , or R n T n , where organic substituents (R = alkyl, aryl or any other) are attached to silicon cage.…”

Effect of cure cycle on curing process and hardness for epoxy resin

“…This is because they maintain an excellent balance between various properties such as adhesion properties, electrical insulation properties, humidity resistance, heat resistance, and mechanical properties [1][2][3][4][5]. Determination of cure cycle is one of the important factors for successful fabrication of thick epoxy product with dependable quality and at low cost.…”