A study of Mechanical Properties and Processability of Blown Films Using b-LLDPE and LDPE Blends.

(2010) A study of Mechanical Properties and Processability of Blown Films Using b-LLDPE and LDPE Blends. Masters thesis, King Fahd University of Petroleum and Minerals.

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Arabic Abstract

البولي إيثيلين منخفض الكثافة الخطي هو مبلمر مصنع محليا ويمتلك خصائص ميكانيكية ممتازة إذا ما قورن بالبولي إيثيلين منخفض الكثافة, لكنه أصعب منه تصنيعا. الهدف من هذه الرسالة هو خلط هذين المبلمرين لتحسين وتسهيل تصنيع البولي إيثيلين المنخفض الكثافة الخطي. قبل البدء بخلط المبلمرين تمت دراسة أثر قوة الشد وقوة نفخ الهواء على الخصائص الميكانيكية لكل منهما على حدة, ثم تم خلطهما بالنسب التالية: 5, 10, 15, 20 و 50 % من البولي إيثيلين منخفض الكثافة. تم دراسة تحمل الأغشية للشد وللتصادم وللشق, واتضح أنه بإضافة إلى 20% من البولي إيثيلين منخفض الكثافة تحسنت قابلية المبلمر على التصنيع كما كان متوقعا. الخصائص الميكانيكية تحسنت أيضا بشكل ملفت وغير متوقع خصوصا مقاومة المبلمر للشق بالاتجاه المعاكس لاتجاه الشد وأيضا صلابة الأغشية بنفس اتجاه الشد. تعتبر هذه النتائج إنجازا جديدا لأنه من المعتاد في حالة تحسن التصنيع فإن الخصائص الميكانيكية ستضعف ولكنها تحسنت بالعموم في هذه الدراسة.

English Abstract

Butene based linear low density polyethylene (b-LLDPE) is a locally made polymer that has superior mechanical properties, but lower processability compared to low density polyethylene (LDPE). In the present study, the aim is to blend the two polymers at different blend ratios to enhance the processability of b-LLDPE. Effects of draw ratio (DR) and blow ratio (BR) on the mechanical properties of b-LLDPE and LDPE films were investigated. Different mechanical tests, such as tensile, impact and tear resistance were studied. Crystallinity and orientation tests of the produced films were carried out for characterization purposes. It was found that a draw ratio of 21 and a blow ratio of 1.6 are optimum selections. Using the abovementioned draw and blow ratios, the effect of blending on the mechanical properties and processability was investigated. Blend ratios of 5, 10, 15, 20 and 50% of LDPE were used. Having a blend ratio of up to 20% of LDPE with b-LLDPE brought a great achievement. Blending with LDPE reduces the torque needed to turn the motor, which lowers the energy consumption and lowers the cost of the process, in turn. From the mechanical tests results, many mechanical properties improved dramatically. Adding up to 20% of LDPE enhanced the yield strength in machine direction except for the 5% LDPE. The tensile strength in MD increased up to 15% LDPE. In both directions, the ductility profiles are similar. There was an enhancement in ductility at blend ratios of 5 and 10 %. At 15 and 20% of LDPE the ductility was almost unaltered. There was an enhancement of about 45% at blend ratios of 15 and 20% in the toughness of the films in machine direction. In the transverse direction, the toughness increased by 50% when adding only 10% of LDPE. The impact properties were affected greatly with the addition of LDPE. With the addition of only 5% of LDPE, the failure energy and the energy to peak force were increased by almost 25%. Adding 10% of LDPE, showed deterioration in the failure energy but the energy to peak force was enhanced. The effect of blend ratio on the Elmendorf tear resistance was carried out. If 5 or 10% of LDPE is added, the enhancement of TD tear resistance will be around 90%. At 15 and 20% of LDPE the enhancement was amazingly 115 and 100%, respectively. In general, the study of blend effect on mechanical properties showed improvement up to 20% LDPE. Furthermore, the torque requirement was reduced with the increase of blend ratio.

Item Type: Thesis (Masters)
Subjects: Mechanical
Department: College of Engineering and Physics > Mechanical Engineering
Committee Advisor: Mezghani, Khaled
Committee Members: Merah, N. and Ben-Mansour, rached
Depositing User: Wael Fallatah
Date Deposited: 24 Jul 2010 08:05
Last Modified: 01 Nov 2019 15:28
URI: https://eprints.kfupm.edu.sa/id/eprint/136335