Augmenting thermal and mechanical properties of epoxy thermosets: The role of thermally-treated versus surface-modified TiO2 nanoparticles

2014 ◽  
Vol 4 (1) ◽  
pp. 54-64 ◽  
Author(s):  
Zakya Rubab ◽  
Adeel Afzal ◽  
Humaira M. Siddiqi ◽  
Shaukat Saeed
Keyword(s):  
Mechanical Properties ◽  
Thermal And Mechanical Properties ◽  
Surface Modified ◽  
Thermally Treated

Effect of Cellulose Functionalization on Thermal and Mechanical Properties of Epoxy Resin

2017 ◽  
Vol 757 ◽  
pp. 62-67 ◽  
Author(s):  
Kritsanachai Leelachai ◽  
Supissara Ruksanak ◽  
Tarakol Hongkeab ◽  
Supakeat Kambutong ◽  
Raymond A. Pearson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Diglycidyl Ether ◽  
Cellulose Content ◽  
Thermal And Mechanical Properties ◽  
Chemical Surface ◽  
Pull Out ◽  
Fiber Bridging ◽  
Surface Modified ◽  
Modified Epoxy

In this study, diglycidyl ether of bisphenol A (DGEBA) cured cycloaliphatic polyamine was modified with functionalized celluloses for improved thermal and mechanical properties. Three different types of surface-modified cellulose, polyacrylamide-g-cellulose (PGC), aminopropoxysilane-g-cellulose (SGC), and carboxymethyl cellulose (CMC), were investigated and used as reinforcing agents in epoxy resins. The storage modulus of these modified epoxy systems was found to significantly increase with addition of cellulose fillers (up to 1 wt. % cellulose content). An improved fracture toughness (KIC) was also observed with increasing cellulose loading content with PGC and SGC. Among the surface-modified celluloses, epoxy modified with SGC was found to have the highest fracture toughness followed by PGC and CMC at 1.0 wt.% cellulose addition due to the chemical surface compatibility. The toughening mechanisms of the cellulose/epoxy composites, measured by scanning electron microscopy (SEM), revealed that fiber-debonding, fiber-bridging, and fiber-pull out were responsible for increased toughness.

Synthesis and Properties of Silica-Modified Polybenzoxazine

2004 ◽  
Vol 449-452 ◽  
pp. 1157-1160 ◽  
Author(s):  
Tarek Agag ◽  
Tsutomu Takeichi
Keyword(s):  
Mechanical Properties ◽  
Ir Spectra ◽  
Ring Opening ◽  
Thermal And Mechanical Properties ◽  
Noticeable Effect ◽  
Hydrolysis And Condensation ◽  
Silica Hybrids ◽  
Thermally Treated

A series of polybenzoxazine-silica hybrids was papered by blending benzoxazine monomer with various ratios of tetraethoxysilane (TEOS) as a precursor for silica. The blends after hydrolysis and condensation of TEOS were thermally treated gradually up to 240oC to afford the hybrids. The IR spectra and DSC showed the completion of the ring opening of benzoxazine monomer and formation of silica by the end of the 240oC cure. The inclusion of silica into polybenzoxazine matrix has a noticeable effect on the thermal and mechanical properties.

scholarly journals Dual role of microcracks: toughening and degradation

2001 ◽  
Vol 38 (2) ◽  
pp. 427-440 ◽  
Author(s):  
G M Nagaraja Rao ◽  
C RL Murthy
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Inelastic Strain ◽  
Dual Role ◽  
Compression Tests ◽  
Defective Structure ◽  
Heating And Cooling ◽  
Thermally Treated

One of the methods of improving the mechanical properties of ceramics is to introduce a defective structure that acts as a restraint for the propagation of cracks. In the present study a detailed investigation was carried out by introducing a defective structure in rock to determine if there is any improvement in properties similar to ceramics. Granite was chosen for the investigation, and the microcracks were introduced by a heating and cooling cycle. Uniaxial compression tests have shown that granite thermally treated to 200°C shows the highest strength, and the strength of granite treated to 400°C is comparable to that of unheated granite. Both ultrasonic images and acoustic-emission monitoring show that for thermally treated samples the stress-induced microcrack and macrocrack nucleation and their growth are retarded. The variations in mechanical properties are explained based on the concept of toughening and degradation. Uniaxial compression tests on unheated and thermally treated granite samples have clearly established the dual role of microcracks, which operate in the toughening and degradation mechanisms.Key words: thermal treatment, microcrack, inelastic strain, ultrasonic C-scan imaging, acoustic emission, toughening.

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