proposed by Jeziorny [ 36 ], the Ozawa analysis [ 37 ], the Ziabicki analysis [ 38 ], and Mo's method [ 39 ] have been developed to describe the non-isothermal crystallization kinetics of polymers. The Kissinger method is inapplicable to a process that
increase in the crystallization rate of Vectra A950 blended with PP and maleic anhydride grafted PP.
Many kinetic models such as Avrami, Ozawa, and Momethods have been used to describe the crystallization behavior of the PP phase and its blend
Non-isothermal crystallization kinetics of isotactic polypropylene (iPP) nucleated with 1,3:2,4-bis(3,4-dimethylbenzylidene)
sorbitol (DMDBS) was studied by using differential scanning calorimetry (DSC). The modified Avrami theory of Jeziorny and
the Mo method were used to analyze the DSC data. The results suggested that the two methods were both suitable for crystallization
kinetics of iPP nucleated with DMDBS. Half time of the crystallisation (t1/2) of virgin iPP was larger than that of nucleated iPP under the same cooling rate. Meanwhile, the required cooling rate of
virgin iPP was higher than that of iPP nucleated with DMDBS in order to reach the same relative crystallinity, both of which
showed that the addition of nucleating agent DMDBS could increase the crystallization rate of iPP. In addition, incorporation
of DMDBS changed the manner of nucleation and development.
Authors:Lenka Stránská, Petra Šulcová, and Jitka Mouchová
This contribution is focused on the synthesis, characterization and optical properties of new inorganic pigments which are environment friendly and can substitute some toxic metals in interesting colour compounds. Pyrochlores belong to the group of high-temperature pigments, and are a variety of actual and potential applications for several materials. Examples include catalysts, thermal barrier coatings, solid electrolytes, nuclear waste forms and host materials for luminescence centers. The pigments were prepared by the solid state reaction and also by method of suspension mixing of materials in the series with increasing content of molybdenum. The pigments were applied into organic matrix and ceramic glaze. The colour properties of these applications were investigated depending on content of Mo, method of preparation and temperature of calcination (1350–1550 °C after step 50 °C). The optimum conditions for their synthesis were determined. The pigments were evaluated from standpoint of their structure, colour and particle sizes. Characterization of Er2Ce2−xMoxO7 pigments (x = 0.1, 0.3, 0.5 and 0.7) suggests that they have a potential to be alternative yellow or orange colourants for paints, plastics, ceramics and building materials.
Authors:S. Jirong, C. Zhaxou, Hu Rongzu, X. Heming, and L. Fuping
The single crystal of lead salt of 3-nitro-1,2,4-triazol-5-one (NTO), [Pb(NTO)2(H2O)] was prepared and its structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, its space group is P21/n with crystal parameters of a=0.7262(1) nm, b=1.2129(2) nm, c=1.2268(3) nm, =90.38(2)°, V=1.0806(2) nm3, Z=4, Dc=2.97 g cm–3, µ=157.83cm–1, F(000)=888. The final R is 0.027. By using SCF-PM3-MO method we obtained optimized geometry for [Pb(NTO)2
H2O] and particularly positions for hydrogen atoms. Through the analyses of MO levels and bond orders it is found that Pb atom bond to ligands mainly with its 6pz and 6py AOs. The thermal decomposition experiments are elucidated when [Pb(NTO)2
H2O] is heated, ligand water is dissociated first and NO2 group has priority of leaving. Based on the thermal analysis, the thermal decomposition mechanism of [Pb(NTO)2
H2O] has been derived. The lattice enthalpy and its lattice energy were also estimated.
Non-isothermal crystallization kinetics of polypropylene (PP), m-isopropenyl-α,α-dimethyl-benzyl isocyanate grafted PP (PP-g-m-TMI), and styrene(St), as comonomer, together with m-TMI grafted PP (PP-g-(St-m-TMI)) was investigated by using differential scanning calorimetry (DSC) under different cooling rates. The crystallization
rates of all samples increased with increasing cooling rate. The relation of the half time of crystallization (t1/2) of the three samples, t1/2(PP-g-(St-m-TMI)) < t1/2(PP-g-m-TMI) < t1/2(PP), implying the introduction of St could effectively improve the degree of grafting of m-TMI, resulting in crystallization temperature increased, and the crystallization rate was the fastest. Three methods, namely,
the Avrami, the Ozawa, and the Mo, were used to describe the crystallization process of the three samples under non-isothermal
conditions. The Avrami and Ozawa neglected the secondary crystallization that follows primary crystallization. The Mo method
can successfully describe the overall non-isothermal crystallization process of all the samples. It has been found that the
F(T)(PP-g-(St-m-TMI)) < F(T)(PP-g-m-TMI) < F(T)(PP), also meaning that the crystallization rate of PP-g-(St-m-TMI) and PP-g-m-TMI were faster than that of PP. The activation energy (ΔE) for non-isothermal crystallization of all samples was determined by using the Kissinger method. The result showed that the
lower value of ΔE for crystallization obtained for PP-g-m-TMI and PP-g-(St-m-TMI) confirmed the nucleating effect of St and m-TMI on crystallization of PP.
energy. It could be ascribed to that CaCO 3 nanoparticles acted as nucleating agents to facilitate the crystallization, however, hindered the crystallization at higher X t . As demonstrated by Jeziorny and Momethods, the addition of CaCO 3 particle