Influence of Moisture on Flax Fiber in Polyethylene Composite Product Manufactured by Rotational Molding Process

2002 ◽  
Author(s):  
S. Panigrahi ◽  
L. G. Tabil ◽  
W. J. Crerar ◽  
S. Sokansanj ◽  
T. Powell ◽  
...  
Keyword(s):  
Flax Fiber ◽  
Rotational Molding ◽  
Molding Process ◽  
Polyethylene Composite ◽  
Composite Product

Simplified Version of Polymer Rotational Molding Manufacturing Method

2016 ◽  
Vol 699 ◽  
pp. 97-103 ◽  
Author(s):  
Laurenţiu Slătineanu ◽  
Oana Dodun ◽  
Margareta Coteaţă ◽  
Gheorghe Nagîţ ◽  
Irina Beşliu
Keyword(s):  
Liquid Phase ◽  
Rotation Speed ◽  
Rotational Molding ◽  
Slow Speed ◽  
Molding Process ◽  
Manufacturing Method ◽  
Polyurethane Resin ◽  
Liquid Material ◽  
Complex Equipment ◽  
Plastic Parts

Rotational molding is a manufacturing method which supposes the rotation of the mold, during the solidification of the liquid phase material, so that finally a part having a hollow could be obtained. The method could be applied in manufacturing of metallic and nonmetallic parts. Usually, the equipment for rotational molding ensures slow speed rotating of the mold around two axes placed perpendicularly each other and this fact led to relatively complex equipment for achieving rotational molding. The capacity of the liquid material to entirely cover the internal walls of the mold depends essentially on the liquid material viscosity, on the rotation speed and on the movements applied to the mold. Simplified equipment including a single rotation movement could be materialized. In order to test such a solution, a preliminary experiment was designed and materialized, by using a device adapted on universal lathe. Thus, the objective of the research presented in the paper was to study if it is possible to achieve plastic parts made by rotational molding using a single rotation movement. A polyurethane resin obtained from two liquid components was used in order to obtain the liquid material that could be introduced in the mold. The research results proved the possibility to use simplified equipment for achieving a rotational molding process, at least in certain cases and with some technological limits.

Banana and Abaca Fiber-Reinforced Plastic Composites Obtained by Rotational Molding Process

2013 ◽  
pp. 130614085148001 ◽  
Author(s):  
Z. Ortega ◽  
M. D. Monzón ◽  
A. N. Benítez ◽  
M. Kearns ◽  
M. McCourt ◽  
...  
Keyword(s):  
Fiber Reinforced ◽  
Rotational Molding ◽  
Molding Process ◽  
Fiber Reinforced Plastic ◽  
Plastic Composites ◽  
Reinforced Plastic

The effect of pressure variations on the formation of gas inclusions in the rotational molding process

2015 ◽  
Vol 35 (5) ◽  
pp. 481-491 ◽  
Author(s):  
Martin Löhner ◽  
Dietmar Drummer
Keyword(s):  
Cycle Time ◽  
Polymer Melt ◽  
Low Pressure ◽  
Rotational Molding ◽  
Molding Process ◽  
Inclusion Removal ◽  
Heating And Cooling ◽  
Polymer Powder ◽  
Major Disadvantage ◽  
Plastic Processing

Abstract The major disadvantage of rotational molding is the cycle time, which is very long compared to other plastic processing methods. A major percentage of the cycle time besides heating and cooling results from the time necessary to remove gas inclusions from the polymer melt, which are trapped while sintering the polymer powder. In this work the formation of gas inclusions is investigated by conducting a cycle time variation on a uniaxial rotational molding machine. The influence of low pressure during melting on the formation of inclusions is investigated by examining sintering experiments with a pressure variation during the melting of the polymer. Sintering experiments are conducted with different melt residence times to investigate the mechanisms of gas inclusion removal. By comparing the time to reach a pore-free polymeric melt, the cycle time reduction potential under low-pressure application while melting the polymeric powder is estimated.

Dynamic Modeling of Thermal Processes in Rotational Molding

Volume 3 ◽  
2004 ◽  
Author(s):  
Kalyanjit Ghosh ◽  
Srinivas Garimella
Keyword(s):  
Heat Transfer ◽  
Energy Consumption ◽  
Plastic Material ◽  
Liquid Pool ◽  
Transient Heat Transfer ◽  
Rotational Molding ◽  
Molding Process ◽  
Heating And Cooling ◽  
Consumption Rates ◽  
Plastic Parts

Transient heat transfer phenomena in the rotational molding of plastic parts are modeled in this study. Natural convection and radiation from the furnace and flue gases to the mold housing are analyzed. Other models include transient heat transfer through the mold, single-phase conduction through the particulate plastic material prior to phase change, melting of the plastic, and heating of the liquid pool. Subsequent staged cooling and solidification of the mold and plastic using a combination of free and forced convection and radiation is also modeled. Information about the properties of the plastic in powder, liquid and solid forms is obtained from the literature. Assumptions about the behavior of the plastic powder and the molten plastic during the rotational operations are also made in accordance with the available literature. The mold wall, melt and solidified plastic regions are divided into a number of finite segments to track the temperature variation with time during the molding process. The corresponding variations in masses and thicknesses of the melt and solidified plastic regions are also estimated. Consequently, the energy consumption rates in the process are estimated. The model is applied to a specific molding process in a commercial rotational molding plant. Parametric studies of the effect of heating and cooling durations on the plastic temperatures and the energy consumption rates are also conducted. These analyses provide insights about opportunities for optimization of the heating and cooling schedules to reduce overall energy consumption and also improve throughput.

scholarly journals Some Mechanical Properties of Coconut Fiber Reinforced Polyethylene Composite to Control Environmental Waste in Ghana

2018 ◽  
Vol 8 (1) ◽  
pp. 1 ◽  
Author(s):  
George Amoako ◽  
Patrick Mensah-Amoah ◽  
Frederick Sam ◽  
Samuel S Sackey
Keyword(s):  
Mechanical Properties ◽  
Natural Fiber ◽  
Control Sample ◽  
Coconut Fiber ◽  
Load Bearing Capacity ◽  
Waste Products ◽  
Polyethylene Composite ◽  
Coconut Husk ◽  
Composite Product ◽  
Water Absorption Test

Polymer products have been applied in all spheres of life and their disposal after use has been a problem. In Ghana, non-biodegradable polymer products in the form of used water-sachet bags is littered everywhere. Coconut husk, which is a natural fiber, is also available as waste. We explore a means of recycling sachet-water bags and coconut husk to yield a useful product. A composite was formed by melting the polyethylene, into which was dispersed coconut fiber, and then allowed to set. Varied masses of fiber were added after which water absorption test, hardness/compressive and flexure tests were conducted on the composite product. The absorption rate of the composite increased with increasing composition of fiber, meaning that the porosity of the material was influenced by the amount of fiber. Increasing the fiber content increased the load needed to compress the sample, indicating an increase in the strength of the composite. The load-bearing capacity increased by 120 % when 450.5 g of fiber was added to the control sample, and further increased to 800 % when the fiber mass was increased to 804.4 g. With an amount of 100 g of fiber added to the polyethylene, the flexure increased by about 5.73 % and by about 31.46 % when 450 g of fiber was added. There was therefore improvement in the mechanical properties of the composite formed, and consequently such waste products can be put to use in applications like the production of ceilings, partition boards, automobile interiors and the likes.

Polypropylene/polyethylene two-layered by one-step rotational molding

2018 ◽  
Vol 38 (7) ◽  
pp. 685-694 ◽  
Author(s):  
Ektinai Jansri ◽  
Narongchai O-Charoen
Keyword(s):  
Particle Sizes ◽  
Linear Low Density Polyethylene ◽  
Rotational Molding ◽  
Molding Process ◽  
Special Equipment ◽  
Blending Method ◽  
Probability Of Success ◽  
One Step ◽  
Flow Apparatus ◽  
Particle Shapes

AbstractAt present, a two-layered product can be molded through various processes. The rotational molding process is a thermoplastics process that can produce products with a two-layered structure; however, it requires special equipment or additional steps in the processing, which make the processing more complex. However, previous research has shown that, through the use of materials with different particle sizes and melting points, two-layered products can also be molded. Thus, this research uses an axial powder flow apparatus to determine the possibility of a two-layered molding between polypropylene (PP) and linear low-density polyethylene (LLDPE). The differences in the particle shapes of a PP homopolymer and copolymer have been considered. The particle sizes of both PPs were determined to be larger than that of LLDPE, and were mixed in a ratio of 50:50 (%wt) using a dry blending method. The results of this experiment show that the two-layered molding of PP and LLDPE using an uncomplicated technique for rotational molding has a high probability of success.

scholarly journals Thermal and Mechanical Analysis of Polyethylene Homo-Composites Processed by Rotational Molding

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 528 ◽  
Author(s):  
Antonio Greco ◽  
Francesca Ferrari ◽  
Maria Grazia Buccoliero ◽  
Greta Trono
Keyword(s):  
Mechanical Properties ◽  
Compression Molding ◽  
Mechanical Analysis ◽  
Rotational Molding ◽  
Reinforcing Bars ◽  
Molding Process ◽  
Bending Tests ◽  
Fiber Placement ◽  
A Value ◽  
Uhmwpe Fibers

This work is aimed at studying the suitability of ultra-high molecular weight polyethylene (UHMWPE) fibers for the production of polyethylene homo-composites processed by rotational molding. Initially pre-impregnated bars were produced by co-extrusion and compression molding of UHMWPE fibers and linear low-density polyethylene (LLDPE). A preliminary screening of different processing routes for the production of homo-composite reinforcing bars was performed, highlighting the relevance of fiber impregnation and crystalline structure on the mechanical properties. A combination of co-extrusion and compression molding was found to optimize the mechanical properties of the reinforcing bars, which were incorporated in the LLDPE matrix during a standard rotational molding process. Apart from fiber placement and an increase in processing time, processing of homo-composites did not require any modification of the existing production procedures. Plate bending tests performed on rotational molded homo-composites showed a modulus increase to a value three times higher than that of neat LLDPE. This increase was obtained by the addition of 4% of UHWMPE fibers and a negligible increase of the weight of the component. Dart impact tests also showed an increased toughness compared to neat LLPDE.

Experimental Analysis of Heat Transfer in Rotational Molding Process

2008 ◽  
Vol 23 (1) ◽  
pp. 93-102 ◽  
Author(s):  
V. Sobotka ◽  
E. Perot ◽  
A. Maazouz ◽  
D. Delaunay
Keyword(s):  
Heat Transfer ◽  
Experimental Analysis ◽  
Rotational Molding ◽  
Molding Process
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