Hybrid Filler (Cellulose/Noncellulose) Reinforced Nanocomposites

From nanocellulose to wood particles: A review of particle size vs. the properties of plastic composites reinforced with cellulose-based entities

“…For example, nanocellulose products and even fine-ground particles or flourstend to involve higher energy input, along with higher costs of preparation (de Assis et al 2017). If there is a need to treat the surfaces or to add a compatibilizing agent to the matrix, then intuitively the required amounts of these agents will tend to be higher when the surface area of the reinforcing particles is increased, as in the case of nanoparticles (Hubbe 2017). In support of this concept, Tarrés et al (2019) observed that specific amounts of coupling agent were needed in polypropylene systems reinforced with henequen strands of different size in order to achieve maximum strength.…”

“…As will be shown, it is already a difficult challenge to find clear evidence for dependencies of composite properties on the dimensions of reinforcing particles, and properties of hybrid composites are yet harder to account for. An earlier review of hybrid composites (Hubbe 2017) found only a few examples of studies giving clear support for the idea that a combination of two different types of reinforcement (including different sizes or shapes) can be beneficial for composite strength. Most results of work involving such hybrid composites either can be understood by "rule of mixtures" estimates or are merely inconclusive with respect to the theory of hybrid composites (Philips 1976).…”

“…The authors also reported evidence of agglomeration of the reinforcing material, especially at higher levels of addition. Longer fibers of similar width are more prone to agglomeration during stirring of a mixture (Hubbe 2017), and such agglomerates can serve as weak points in a composite. Thus, more extensive agglomeration is a possible reason to explain the minor fall-off in strength properties with increasing size of wood flour particles.…”

“…The idea for the present review article first started as a matter of curiosity: Given that it often takes more energy and effort to prepare composites with smaller cellulosebased elements, the question can be asked as to what one can expect to get in return. An initial doubt about whether there is a benefit of using nanocellulose for plastic composites was expressed in an earlier review article (Hubbe 2017), but that publication presented little supporting evidence. A few examples from the literature pertaining to the topic were cited in a more recent conference presentation, titled "Think big: The case against relying just on nanocellulose to reinforce plastic composites" (Hubbe 2018).…”

Physical and mechanical properties of woven kenaf/bamboo fiber mat reinforced epoxy hybrid composites

“…Fiber selection is important since every fiber has its own unique properties. The two reinforcing elements ought to provide unique combinations of properties or synergistic effects as a "hybrid composite", which then can be used for different applications (Hubbe 2017). El-Shekeil et al (2012) studied the influence of fiber content (20%, 30%, 40%, and 50%) on the mechanical properties of kenaf fiber reinforced polyurethane.…”