Plant Based Reinforcements for Thermosets Matrices, Processing and Properties

M. I. ARANGUREN; M.M. REBOREDO

Engineering Biopolymers:Homopolymers, Blends and Composites

CARL HANSER VERLAG GmbH & Co Publishers

Lugar: Munich; Año: 2007; p. 193 - 221

Natural fibers and woodflour are perhaps the oldest additives utilized in thermoset plastics. Their application dates back to the introduction of Bakelite on the market; these fibers were incorporated to phenolic resins in order to provide impact resistance, reduce cost, and control shrinkage. Bulk fibers with random orientation and no binder (matrix) can find applications as insulating materials and filters. Fibers with random orientation and some binder are used in fiberboards and medium density panels. Natural fibers incorporated into a polymer matrix result in composites with potential load-bearing applications. Natural-reinforced plastics (NRP) offer an attractive alternative for costeffective applications; however, severe limitations are imposed due to their low strength and modulus. Traditionally, woodflour-filled molding compounds have been extensively used for products, such as pan-handles, electric meter cases, and parts of cars. In addition, natural fiber-reinforced composites are particularly suited to structural and decorative applications in the transport, marine, offshore and construction industries. The utilization of cellulose-based natural fibers as reinforcement for thermosets in general, can be effective in the production of low cost, low weight (due to the fiber low density), and ecologically friendly composites. Natural fibers are renewable resources, abundantly available, especially in tropical areas. On the other hand, their poor dimensional stability, cracking, and degradation of mechanical properties because of their moisture uptake create the standard problems with these materials. Polymeric materials intended for use as matrices should be inexpensive, available, easily processed, and with low viscosity. One obvious effect of the incorporation of fillers into polymers is a noticeable increment of the viscosity. For this reason, an increase of energy consumption is expected for some processing methods. The application of natural fibers as reinforcements in composite materials requires, just as for glass fiber composites, strong adhesion to the matrix, regardless of the selected matrix type. The processing conditions play, next to the mechanical properties of natural fibers, an important role in the industrial use of these materials. Thermal analysis is quite important because processing temperatures involved in composite manufacture approach those, at which the fibers start to degrade. The mechanical and other physical properties of the composites are generally dependent on the fiber/filler characteristics, the respective volume content in the composite, the fiber arrangement or filler dispersion, the processing method, the selected matrix, and the interface/interphase between both components. For special performance requirements, hybrid composites made of natural and conventional fibers can be prepared with desired properties.and woodflour are perhaps the oldest additives utilized in thermoset plastics. Their application dates back to the introduction of Bakelite on the market; these fibers were incorporated to phenolic resins in order to provide impact resistance, reduce cost, and control shrinkage. Bulk fibers with random orientation and no binder (matrix) can find applications as insulating materials and filters. Fibers with random orientation and some binder are used in fiberboards and medium density panels. Natural fibers incorporated into a polymer matrix result in composites with potential load-bearing applications. Natural-reinforced plastics (NRP) offer an attractive alternative for costeffective applications; however, severe limitations are imposed due to their low strength and modulus. Traditionally, woodflour-filled molding compounds have been extensively used for products, such as pan-handles, electric meter cases, and parts of cars. In addition, natural fiber-reinforced composites are particularly suited to structural and decorative applications in the transport, marine, offshore and construction industries. The utilization of cellulose-based natural fibers as reinforcement for thermosets in general, can be effective in the production of low cost, low weight (due to the fiber low density), and ecologically friendly composites. Natural fibers are renewable resources, abundantly available, especially in tropical areas. On the other hand, their poor dimensional stability, cracking, and degradation of mechanical properties because of their moisture uptake create the standard problems with these materials. Polymeric materials intended for use as matrices should be inexpensive, available, easily processed, and with low viscosity. One obvious effect of the incorporation of fillers into polymers is a noticeable increment of the viscosity. For this reason, an increase of energy consumption is expected for some processing methods. The application of natural fibers as reinforcements in composite materials requires, just as for glass fiber composites, strong adhesion to the matrix, regardless of the selected matrix type. The processing conditions play, next to the mechanical properties of natural fibers, an important role in the industrial use of these materials. Thermal analysis is quite important because processing temperatures involved in composite manufacture approach those, at which the fibers start to degrade. The mechanical and other physical properties of the composites are generally dependent on the fiber/filler characteristics, the respective volume content in the composite, the fiber arrangement or filler dispersion, the processing method, the selected matrix, and the interface/interphase between both components. For special performance requirements, hybrid composites made of natural and conventional fibers can be prepared with desired properties.