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.

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 Studies on Sheet Explosive Formulation Based on Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine and Hydroxyl Terminated Polybutadiene

2017 ◽  
Vol 67 (6) ◽  
pp. 617 ◽  
Author(s):  
Suresh Kumar Jangid ◽  
Mrityunjay Kumar Singh ◽  
Vasant Jadavji Solanki ◽  
Rabindra Kumar Sinha ◽  
Krothapalli Prabhakara Subrahmania Murthy
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Kinetic Method ◽  
Decomposition Kinetics ◽  
Thermal And Mechanical Properties ◽  
Binder System ◽  
Scanning Calorimetry ◽  
Velocity Of Detonation ◽  
Kinetics Of

<p class="p1">The effect of replacing hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in HTPB-binder on the performance, sensitivity, thermal, and mechanical properties of the sheet explosive formulation has been studied. The maximum loading of HMX was achieved up to 78 per cent in HTPB-binder system. The velocity of detonation (VOD) of HMX-based sheet explosive was observed about 7300 m/s which is marginally higher than existing RDX-based sheet explosive formulation (RDX/HTPB-binder, 80/20). The VOD trends were verified by theoretical calculation by BKW code using FORTRAN executable program. The thermal decomposition kinetics of sheet explosive formulations was investigated by differential scanning calorimetry. The activation energy for sheet explosive formulation HMX/HTPB-binder (78/22) was calculated using Kissinger kinetic method and found to be 170.08 kJ/mol, infer that sheet explosive formulation is thermally stable.</p>

Thermal and Mechanical Properties of Epoxy/Polyurethane Blend System Initiated by Cationic Latent Thermal Catalyst

2007 ◽  
Vol 119 ◽  
pp. 215-218 ◽  
Author(s):  
Soo Jin Park ◽  
Su Ja Seok ◽  
Byung Gak Min
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Hydrogen Bonding ◽  
Critical Stress ◽  
Interfacial Properties ◽  
Hydroxyl Groups ◽  
Thermal And Mechanical Properties ◽  
Thermal Stabilities ◽  
Cure Behavior ◽  
Maximum Value

In this work, the blend of diglycidylether of bisphenol A (DGEBA) and modified polyurethane (PU) was prepared and characterized the cure behavior and mechanical interfacial properties. The N-benzylpyrazinium hexafluoroantimonate was used as a cationic initiator for cure, and the content of PU was varied within 0~20 phr. The cure behavior and mechanical interfacial properties were studied by DSC and the critical stress intensity actor (KIC) measurements. Also thermal stabilities were carried out by TMA and TGA analyses. It is found that the cure activation energy (Ea) was slightly increased on increasing the PU content, and a maximum value was noted at 10 phr PU. The mechanical interfacial properties measured from KIC showed a similar behavior with the results of conversion. These results were probably due to the increase of the hydrogen bonding between the hydroxyl groups of DGEBA and isocyanate groups in PU.

Reuse potential of functionalized thermoplastic waste as reinforcement for thermoset polymers: Mechanical properties and erosion resistance

2021 ◽  
pp. 002199832110370
Author(s):  
Tihomir Kovačević ◽  
Saša Brzić ◽  
Melina Kalagasidis Krušić ◽  
Jovica Nešić ◽  
Ljubica Radović ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Erosion Resistance ◽  
Unsaturated Polyester ◽  
Chemical Activation ◽  
Mining Industry ◽  
Dynamic Mechanical Properties ◽  
Variable Loading ◽  
Polymer Waste ◽  
Dynamic Mechanical

Two types of polymer waste materials, poly(ethylene terephthalate) (PET) and polycarbonate based Colombian Resin (CR-39), were used for the designing of fully recycled composite materials. Waste PET was employed for the synthesis of thermoset unsaturated polyester resin (UPR), while CR-39 was used as reinforcement in the UPR matrix. Prior to mixing, CR-39 particles were subjected to oxidation and chemical activation using acids/base and ethanol amine, respectively. The effect of the modifier type and variable loading of the activated CR-39 particles on mechanical and dynamic-mechanical properties of the corresponding composites was investigated. The greatest improvement in the tensile and flexural strength of UPR resin was achieved with the composite containing 0.5 wt% of amine activated filler particles, 96.0% and 62.2%, respectively. The Arrhenius equation was used to calculate the activation energy for glass transition from dynamic mechanical properties measured at various frequencies. The activation energy of the main transition for UPR resin and composites were calculated to be 173 and 350 kJ·mol−1 indicating that reinforcement results in an increase in the energy barrier to macromolecules viscoelastic relaxation. In addition, erosion resistance was studied during exposure of samples to cavitation tests. According to the obtained results, these materials can be applied in construction and mining industry.

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