Properties of Moldings Prepared from LDPE-Pumpkin Seed Hulls Blend

• Main Authors: Karolina Głogowska, Janusz Sikora, Ludmila Dulebova
• Format: Article
• Language: English
• Published: Society of Polish Mechanical Engineers and Technicians 2017-12-01
• Series: Advances in Science and Technology Research Journal
• Subjects: injection molding; low-density polyethylene; natural filler; pumpkin seed hulls
• Online Access: http://www.journalssystem.com/astrj/Properties-of-moldings-prepared-from-LDPE-pumpkin-seed-hulls-blend,74654,0,2.html

In recent decades, standard polymer blends for different applications have been more and more often replaced by blends containing raw materials. The use of natural materials as filler in thermoplastics brings both economic and environmental benefits. The use of a given vegetable filler depends on the geographic location and natural occurrence of the vegetables in a given geographic region. In Poland, for instance, the pumpkin is one of such vegetables. They are used for producing oil which is pressed from pumpkin seeds. Pumpkin seeds are then collected, dried and purified to produce waste material in hull form. Particles of ground pumpkin seed hulls with varying sizes and weight-in-weight concentration ranging from 0% to 20% relative to the matrix are used as filler in low-density polyethylene. Pumpkin seed hulls are ground and sieved. Four fractions of hulls with different particle sizes are produced: <0.2mm, 0.2mm-0.4mm, 0.4mm-0.6mm, 0.6mm-0.8mm. The paper reports the results of investigation of the mechanical properties, i.e., strength properties determined by static tensile testing and hardness measurement, of injection molds produced at constant processing parameters. In addition, the cross sections of the obtained products are subjected to microscopic examination. Relationships are determined between tensile modulus, maximum tensile stress, tensile stress at yield, maximum tensile strain, tensile strain at yield as well as Shore hardness and weigh-in-weight concentration of the powdered natural filler and its grain sizes. Finally, relevant conclusions are drawn.