Evaluation of Hot- Gas And Heated Tool Weldments of Polypropylene/Bone Particulate Composites

Evaluation of Hot- Gas And Heated Tool Weldments of Polypropylene/Bone Particulate Composites.

ABSTRACT

The evaluation of Hot-Gas and Heated-Tool weldments of Polypropylene/Bone composite was conducted. The composites were formulated by incorporating up to 30% by weight of calcined cow bone powder at an interval of 5% and -75µmsieved size was used as reinforcing phase during compounding process.

The polypropylene materials (in unreinforced state) and various polypropylene/bone composites were welded, using hot-gas and heated-tool welding processes.

Mechanical properties (tensile strength, flexural strength, impact strength and hardness) and physical properties (density, water absorption, degradability and morphology) of polypropylene and polypropylene/bone composite in both unwelded and welded conditions were examined.

Results obtained showed increase in density (by 40% at 30% reinforcement); the amount of water absorbed increased as the time of immersion increased. Although the unreinforced polypropylene was saturated after 192 hrs of immersion in water, the reinforced composite’s water uptake continued beyond 192 hrs in proportion of filler amount.

Similarly, there were marked improvements in mechanical properties in the Unwelded Composite (UWC), which was attributed to the reinforcing ability of the bone. However, relatively lower values were recorded when welded samples were examined.

More so, there were drops in tensile strength after 15% (40.91MPa) and 20% (41.54 MPa) in Heated Tool Weldments (HTW) and Hot Gas Weldments (HGW) respectively. On the basis of comparison, these values showed that at 15% reinforcement addition, HTW has strength value 16.70% lower than UWC of the same composition (15% bone).

INTRODUCTION

The development of many technologies that make our existence so comfortable depends largely on the availability of suitable materials (Callister, 2007).

However, most of these technologies require a material with unusual combination of properties (e.g. high specific strength, magnetic–transparent, conductive–transparent, catalytic–magnetic, huge yet invisible to human eye and so on), which indeed exceed the domain of our conventional metal alloys, ceramics, polymers, heat treatments etc (Luigi and Gianfranco, 2005;Hanemann and Vinga 2010).

Nevertheless, the use of compositesas another class of engineering materials has proven to be vital and a promising candidate in the areas of these advanced technologies. Other answers to these contemporary developments include bio-technology, nanotechnology to mention a few.

Composites were developed to improve on the properties (strength to weight ratio, good corrosion resistance, thermal stability etc) of a monolithic material so that it could be used in sophisticated areas such as aviation (where high specific strength is desired), marine (where low weight and high corrosion resistance guaranty safety), sporting equipment (where less weight is appreciated), and many other applications which include high performance rocket-motor and pressure vessels (Harris, 1999).

Composites are made up of primarily two major individual materials referred to as constituent materials. These constituent materials are termed as matrix and reinforcement. At least one portion of each type is required. The matrix material surrounds and supports the reinforcement materials by maintaining their relative positions; while the reinforcements impart their special mechanical and physical properties to enhance the matrix properties.

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CSN Team.

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