scholarly journals Effect of Polymerization Conditions on Thermal and Mechanical Properties of Ethylene/1-Butene Copolymer Made with Ziegler-Natta Catalysts

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mostafizur Rahaman ◽  
M. Anwar Parvez ◽  
J. B. P. Soares ◽  
I. A. Hussein
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Yield Stress ◽  
Hydrogen Pressure ◽  
Polymerization Reaction ◽  
Polymerization Temperature ◽  
Thermal And Mechanical Properties ◽  
Ethylene Pressure ◽  
Polymerization Conditions ◽  
Ziegler Natta Catalysts

The effect of polymerization conditions on thermal and mechanical properties of ethylene/1-butene copolymers synthesized through titanium-magnesium-supported Ziegler-Natta catalysts was studied. The increase in hydrogen pressure leads to a decrease in molecular weight (MW), storage modulus, and melting temperature. However, it yields an increase in molecular weight distribution (MWD),tan⁡δ, % crystallinity, tensile modulus, yield stress, and strain at break. The effects of ethylene pressure and polymerization temperature on the copolymer MW, MWD and thermal and mechanical properties have been investigated. However, the impacts of ethylene pressure and polymerization temperature on copolymer modulus, tensile strength, % crystallinity, crystallization peak temperature, yield stress, strain at break, and yield strain are marginal. The hydrogen pressure plays a major role in controlling the copolymer properties because it acts as an efficient chain transfer agent during polymerization reaction. The MW is the key parameter that influences flow activation energy. However, the other mechanical, dynamic mechanical, and thermal properties not only depend on MW but are also influenced by other parameters.

scholarly journals Correlation of Polymerization Conditions with Thermal and Mechanical Properties of Polyethylenes Made with Ziegler-Natta Catalysts

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
M. Anwar Parvez ◽  
Mostafizur Rahaman ◽  
M. A. Suleiman ◽  
J. B. P. Soares ◽  
I. A. Hussein
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Hydrogen Pressure ◽  
Catalyst Activity ◽  
Thermal And Mechanical Properties ◽  
Polymer Yield ◽  
Flow Activation Energy ◽  
Ethylene Pressure ◽  
Polymerization Conditions ◽  
Ziegler Natta Catalysts

In this study, the synthesis of polyethylenes has been carried out with titanium-magnesium supported Ziegler-Natta catalysts in laboratory-scale reactors. A correlation of different polymerization conditions with thermal and mechanical properties of polyethylenes has been established. It is seen that there is lowering of molecular weight (Mw), polymer yield, and catalyst activity at high hydrogen pressure and high temperature. The Mw, polymer yield, and catalyst activity are improved with the increase in ethylene pressure. Dynamic mechanical analysis (DMA) results show that the increase in temperature and hydrogen pressure decreases storage modulus. The samples with higher Mw showed high activation energy. The melting point decreases with the increase in hydrogen pressure but increases slightly with the increase in ethylene pressure. It is seen that the increase in reaction temperature, ethylene pressure, and hydrogen pressure leads to an increase in crystallinity. The tensile modulus increases with the increase in hydrogen pressure and can be correlated with the crystallinity of polymer. The Mw has a major influence on the flow activation energy and tensile strength. But the other mechanical and thermal properties depend on Mw as well as other parameters.

Weldability of pipe grade polyethylenes as realized from thermal and mechanical properties assessments

2016 ◽  
Vol 36 (8) ◽  
pp. 853-860 ◽  
Author(s):  
Vahabodin Goodarzi ◽  
Zahed Ahmadi ◽  
Mohammad Reza Saeb ◽  
Farkhondeh Hemmati ◽  
Mehdi Ghaffari ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Molecular Weight ◽  
Aging Process ◽  
Pipe Production ◽  
Lamellar Thickness ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Injection Molded ◽  
The One

Abstract Since polyethylene (PE) has been widely accepted for the production of high-pressure fluid conveying pipelines, studies devoted to weldability of PE connections were always of major importance. In this study, two industrial PE grades designed for pipe production, namely PE80 and PE100, were injection molded, cut, and then welded as PE100-PE100, PE100-PE80, and PE80-PE80. The heat-welded joints were assessed by differential scanning calorimetry and tensile measurements. The results obtained from thermal and mechanical analyses were compared with equivalents for aged samples. Thermal analysis revealed that the melting point of the PE100-PE100 sample is obviously larger than the one for the PE80-PE80 joint, for the PE80 chains deteriorate the crystallization of PE100. Further, the PE80-PE80 sample showed the lowest lamellar thickness and crystalline molecular weight among the studied joints. The aging process was found to increase lamellar thickness and molecular weight, though in the PE100-PE100 sample such quantities very limitedly increased. The yield stress of aged joints was higher than that for just-prepared samples, while an inverse trend was seen for strain at break. From a practical viewpoint, the PE100-PE100 welds offer better properties.

Role of important parameters in ring opening polymerization of polylactide

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Paramjit Kaur ◽  
Rajeev Mehta ◽  
Sidh Nath Upadhyay
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Side Reaction ◽  
Polymerization Reaction ◽  
Polymerization Temperature ◽  
Polymer Yield ◽  
A Value ◽  
Prolonged Reaction Time ◽  
Anhydrous Solvent

Abstract Different parameters, namely polymerization temperature, polymerization time, monomer/initiator ratio, nature of the initiator, amount of water or other impurities etc. are very significant for polymerization reactions either in bulk or solution. Monomer to initiator ratio has a very significant role in polymerization reactions and a value ranging from 50 to 5000 that has been reported by different researchers. Recrystallization of the monomer removes the meso compounds from the monomer, which absorbs the moisture and effects polymerization reaction. So, it is necessary to recrystallize the monomer with any anhydrous solvent like dry toluene, ethyl acetate etc. Prolonged reaction time cannot increase the polymer yield; it generally causes the decrease of molecular weight and broadening of molecular weight distribution of formed polymers. This is probably due to the transesterification side reaction in polymerization, intensifying at prolonged time periods. Several groups like hydroxyl and carboxylic acid affect the polymerization rate.

Experiment Research on Influence Factors of Ring-Opening Polymerization in Making PDLLA

2011 ◽  
Vol 183-185 ◽  
pp. 1879-1882
Author(s):  
Song Liu ◽  
Li Na Sun
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Influence Factors ◽  
Ring Opening Polymerization ◽  
Polymerization Temperature ◽  
Experiment Research ◽  
Time Duration ◽  
Vacuum Degree ◽  
Temperature Time ◽  
Polymerization Conditions

The paper research on the factors of the lactide polymerization, which primarily were ontology purity, dosage of initiator, polymerization temperature, time and vacuum degree, etc. According to the molecular weight measuring in different conditions of synthesis PDLLA, the results shows that, through the control of polymerization conditions higher molecular weight of PDLLA can obtain, main parameters as the quality ratio of initiator and monomers is about 0.03%, the polymerization temperature is 140°C, time duration is 48h and vacuum is 0.05 mmHg.

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