Malik Jehanzeb Khurram - Academia.edu (original) (raw)
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Papers by Malik Jehanzeb Khurram
Revista de Chimie, 2001
Utility of polymeric material is a major contribution to the production of waste, particularly in... more Utility of polymeric material is a major contribution to the production of waste, particularly in Pakistan. An easy escape to it is the damping in the land which is not commendable for an environmental point of view. On the other hand, the aging of polymer is analogous to its burial conditions under the soil in the absence of light. Therefore, in this research report, two different brands of polyethylene carrying bags were investigated. One sample was obtained from Pakistan abbreviated as sample "Y" while the other from Canada abbreviated as "E". In order to accelerate the degradation process and to observe the impact of aging in a shorter span of time, these samples were heated at an elevated temperature (80°C) in an oven for the period of 20 days. The samples were characterized before and after aging with an interval of 2 days by applying different techniques like FT-IR, SEM, DSC, and thermogravimetric analysis (TGA). Carbonyl peak at 1715 cm-1 was observed only in the case of sample "E" displaying carbonyl index value as 28.45 % after 20 days of aging. The SEM images before and after aging revealed that the degradation took place at preferential sites in case of sample "Y" and at numerous sites in case of sample "E". The results of percent crystallinity obtained by DSC showed an increasing pattern with aging for both the samples and was high in case of sample "E." The activation energy determined by using Flynn-Wall-Ozawa showed a decreasing pattern for both the samples with aging. It concluded that the thermal aging initiates the process of degradation which was then accelerated by heating in TGA oven. The order of reaction was slightly decreased after aging for both the samples and was found to be independent of the heating rate.
Journal of Applied Polymer Science
The kinetics of thermal degradation of standard and commercial polyethylene (PE) samples is inves... more The kinetics of thermal degradation of standard and commercial polyethylene (PE) samples is investigated, by employing different methods like Flynn-Wall-Ozawa, Coats-Redfern, Kissinger, and Augis-Bennett. The order of reaction obtained was 0.741 and 1.124 for standard and commercial samples, respectively. The activation energy obtained in this way was 279.6–311.0 kJ/mol and 300.5–374.1 kJ/mol for standard and commercial samples, respectively, depending upon the method used. The activation energy obtained by different methods decreases in the order Flynn-Wall-Ozawa» Augis and Bennett» Kissinger» Coats and Redfern. It is observed that most of the methods deviated from the experimental results, in low (0.1–0.3) degree of conversion region but worked well in the middle (0.5–0.7) degree of conversion region. It has also been noticed that both the order and activation energy were slightly dependent over the heating rate and degree of conversion. © 2011 Wiley Periodicals, Inc. J Appl Polym...
Revista de Chimie, 2001
Utility of polymeric material is a major contribution to the production of waste, particularly in... more Utility of polymeric material is a major contribution to the production of waste, particularly in Pakistan. An easy escape to it is the damping in the land which is not commendable for an environmental point of view. On the other hand, the aging of polymer is analogous to its burial conditions under the soil in the absence of light. Therefore, in this research report, two different brands of polyethylene carrying bags were investigated. One sample was obtained from Pakistan abbreviated as sample "Y" while the other from Canada abbreviated as "E". In order to accelerate the degradation process and to observe the impact of aging in a shorter span of time, these samples were heated at an elevated temperature (80°C) in an oven for the period of 20 days. The samples were characterized before and after aging with an interval of 2 days by applying different techniques like FT-IR, SEM, DSC, and thermogravimetric analysis (TGA). Carbonyl peak at 1715 cm-1 was observed only in the case of sample "E" displaying carbonyl index value as 28.45 % after 20 days of aging. The SEM images before and after aging revealed that the degradation took place at preferential sites in case of sample "Y" and at numerous sites in case of sample "E". The results of percent crystallinity obtained by DSC showed an increasing pattern with aging for both the samples and was high in case of sample "E." The activation energy determined by using Flynn-Wall-Ozawa showed a decreasing pattern for both the samples with aging. It concluded that the thermal aging initiates the process of degradation which was then accelerated by heating in TGA oven. The order of reaction was slightly decreased after aging for both the samples and was found to be independent of the heating rate.
Journal of Applied Polymer Science
The kinetics of thermal degradation of standard and commercial polyethylene (PE) samples is inves... more The kinetics of thermal degradation of standard and commercial polyethylene (PE) samples is investigated, by employing different methods like Flynn-Wall-Ozawa, Coats-Redfern, Kissinger, and Augis-Bennett. The order of reaction obtained was 0.741 and 1.124 for standard and commercial samples, respectively. The activation energy obtained in this way was 279.6–311.0 kJ/mol and 300.5–374.1 kJ/mol for standard and commercial samples, respectively, depending upon the method used. The activation energy obtained by different methods decreases in the order Flynn-Wall-Ozawa» Augis and Bennett» Kissinger» Coats and Redfern. It is observed that most of the methods deviated from the experimental results, in low (0.1–0.3) degree of conversion region but worked well in the middle (0.5–0.7) degree of conversion region. It has also been noticed that both the order and activation energy were slightly dependent over the heating rate and degree of conversion. © 2011 Wiley Periodicals, Inc. J Appl Polym...