The main goals of the research were to develop the new types of inexpensive reinforced polyurethane (PUR) elastomers and to study the effect of different commercial fillers on the density and mechanical properties of the developed materials. Two types of inexpensive commercial fillers based on synthetic and natural polymers have been studied: expandable polystyrene beads (macrofillers) of size 0.254-2.54 mm, and wood flour and starch (microfillers) of size 0.212-0.425 mm. The quantitative relationships between the filler nature, size, content, density, and various mechanical properties have been developed.For both fillers it was found that PUR elastomers produced with less filler content (up to 5-10%) showed improved mechanical properties over the Downloaded from composites made with higher filler content (up to 10-30%). Regardless of the filler content, all filled elastomers demonstrated improvement of tensile properties over unfilled elastomers. The maximal improvement of tensile properties has been found as 10% for macrofillers, and 5% for microfillers. All developed materials are based on commercial formulations and mixing, metering, and pouring equipment. Thus, these materials are easy to commercialize. The developed reinforced cold-curing PUR composites have been recommended as inexpensive materials for structural, thermal insulation, and packaging applications, especially for in situ production.
A comparison analysis has been undertaken to study the effect of different wood fillers on density and mechanical properties of two different types of commercial polyurethane (PUR) foams: low-density flexible foams and high-density rigid foams. The micro-fillers used were based on wood flour particles of size 70-250 microns (wood waste of furniture industry). The relationships between the filler size and content, density and various mechanical properties - compression test, compression force deflection test and modulus of elasticity have been studied. It was found that micro-fillers provide various effects depending on flexibility and density of PUR foams. For low-density flexible PUR foams, the density and mechanical properties increased for both types of fillers. However, for high-density rigid PUR foams these effects were just the opposite: the density and compression strengths decreased for both types of fillers. Explanation of the observed effects should take into consideration the chemical nature and physical structure of flexible and rigid PUR binders based on various types of polyol-isocyanate systems, as well as chemical and physical affiliation of cellulose based fillers with the matrices.
The objective of the research was to develop and study the properties of cellular or porous Ultra High Molecular Weight (UHMW) Polyethylene for biomedical applications. The process, based on the leaching technique, does not require any modification in processing equipment, is environment-friendly and uses raw materials approved by the FDA for in vivo medical applications. It is possible to produce porous polymers having predetermined pore size, pore shape and porosity using the leaching technique. The pores are interconnected and well-distributed throughout the threedimensional volume of the sample. The size, shape and content of the porogen in the molding mixture greatly affect the physical properties of the pores in the final porous sample. Maximum porosity of 60% was obtained. The developed porous UHMW Polyethylene, which is permeable by liquids, can be used as a substrate matrix in bone regeneration and in hip-and knee joint replacements. With adequate lubrication, the porous implants would prevent the formation of polymer debris due to friction and thereby increase the life of the biomedical implants. The new generation of developed porous polymers could be used in a wide range of medical and bioengineering applications.
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