In this research, the use of layered double hydroxides (LDHs) as ultraviolet (UV) light-protecting additives for
PP is explored. Different LDHs, such as ZnTi, ZnSn, ZnGa, ZnCr and CdCr LDHs, were prepared and their UV
absorptions were characterized. The ZnTi LDHs showed higher UV absorption than the other four metallic
combinations and were further organically modified with dodecylbenzene sodium sulfonate (SDBS) and
lauric acid (LA). Nanocomposites of polypropylene (PP) with four different types of LDHs, ZnTi, ZnSn,
ZnTi-SDBS and ZnTi-LA, were prepared at concentrations of 5%. The crystallinities and layered structures
of all the metallic combinations of LDHs were characterized by wide angle X-ray spectroscopy (WAXS)
and ultraviolet visible (UV-vis) absorption spectroscopy, and their crystal morphologies were studied by
scanning electron microscopy (SEM). The decomposition and thermal properties of the nanocomposites
and pure PP were analyzed by thermogravimetric analysis (TGA) and transmission electron microscopy
(TEM) and by their photo-oxidation behavior. The addition of these organically modified and unmodified
LDHs showed significant changes in the thermal decomposition of PP. The thermal stability of PP was
increased to around 70 C by the addition of SDBS-modified ZnTi LDHs (5% by weight), and an increase
in induction time of about 300% was determined.
Tang, Zhenghua(University of Pretoria, 2007-08-01)
Thinner walled (about 6 mm thickness) line pipe steels for smaller diameter pipelines tend to have a relatively high ratio of yield strength to ultimate tensile strength (YS/UTS) of 0.93 or higher. This study focused on ...
Semi-solid metal high pressure die casting was used to produce plates from traditional wrought Al-Mg-Si alloys 6082 and 6004, as well as from traditional casting Al-Si-Mg alloys A356 and F357. The high Si-content of the ...
Mutombo, Kalenda; Du Toit, Madeleine(Elsevier, 2011-12)
The fatigue life of aluminium 6061-T651 at various applied stress amplitudes in the unwelded and
welded condition was found to be significantly reduced on immersion in a 3.5% NaCl simulated sea water
solution, compared ...