Evaluation of continuous and discrete melting endotherms in determination of structural heterogeneities in Ziegler-Natta catalyzed linear low density polyethylene
Journal Title: Polyolefins Journal - Year 2016, Vol 3, Issue 2
Abstract
Ethylene / 1-butene copolymers at different comonomer levels were synthesized using Ziegler-Natta catalyst to evaluate the applicability of thermal fractionation methods in predicting chemical composition distribution (CCD). The continuous melting endotherms by DSC were converted to continuous CCD, and the average comonomer contents were compared with NMR results. DSC underestimated comonomer content specifically at higher levels and was more sensitive to the drawn baseline. The thermally fractionated melting endotherms by SSA method were deconvoluted and transformed into discrete CCDs. SSA method underestimated average comonomer content even more, however results were more reproducible. The main shortcoming of the thermal methods was the inability of short ethylene sequences in forming discernible lamella thicknesses at high comonomer levels. Calibration curves were created for converting the predicted comonomer contents into absolute values and used for studying industrial LLDPEs with different comonomer levels. It was shown that SSA provides more reliable results and correlates more reasonably to the measured densities.
Authors and Affiliations
Mostafa Ahmadi, Seyed Mohammad Mehdi Mortazavi, Saeid Ahmadjo, Majid Zahmati, Khosrow Valieghbal, Davoud Jafarifar, Reza Rashedi
Keywords
Related Articles
- EP ID EP283164
- DOI 10.22063/POJ.2016.1332
- Views 119
- Downloads 0
Evaluation of effects of thymolphthalein on thermooxidative stability of polypropylene
The present work is aimed to find a new and efficient type of antioxidants for polypropylene. Hence, effects of 3,3-bis(4-hydroxy-2-methyl-5-propan-2-ylphenyl)-2-benzofuran-1-one, generally known as thymolphthalein, on t...
Propene-cycloolefin polymerization
Highly active metallocenes and other single site catalysts have opened up the possibility of polymerizing cycloolefins such as norbornene (N) or of copolymerizing them with ethene (E) or propene (P). The polymers obtaine...
Production of titanium tetrachloride (TiCl4) from titanium ores: A review
Titanium (Ti) is the ninth most abundant element on earth. The titanium mineral ores are widely distributed in different parts of the world. The two main ores of titanium include rutile (TiO2) and ilmenite (FeO.TiO2). It...
Synthesis and identifcation of polystyrene via conventional and controlled radical polymerization methods: Effect of temperature, initiator and transfer agent on molecular weight and reaction rate
Polystyrene (PSt) has been known as one of the important polymers with a wide range of applications. Ability to synthesize PSt with different but predictable molecular weights for various applications is very important i...
Morphology control of clay-mineral particles as supports for metallocene catalysts in propylene polymerization
Spray dry granulation of clay minerals was studied to obtain clay mineral base support material for metallocene supported olefin polymerization catalysts. The morphology of the granules was strongly influenced by the nat...