Department of Civil & Environmental Engineering

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Browsing Department of Civil & Environmental Engineering by Author "Adekomaya, O.S."

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    Open Access
    Fracture Mechanisms and Failure Modes in Biocomposites and Bionanocomposites
    (Nova Publisher, 2017-07) Sadiku, E.R.; Agboola, O.; Ibrahim, I.D.; Olubambi, P.A.; Avabaram, B.R.; Bandla, M.; Kupolati, W.K.; Tippabattini, J.; Varaprasad, K.; Agwuncha, S.C.; Oboirien, B.O.; Phiri, G.; Nkuna, C.; Durowoju, M.O.; Owonubi, S.J.; Fasiku, V.O.; Aderibigbe, B.A.; Ojijo, V.O.; Biotidara, O.F.; Adeboje, A.O.; Adekomaya, O.S.; Aderibigbe, I.; Jamiru, T.; Dludlu, M.K.
    There are various mechanisms that can be responsible for material fracture which can ultimately lead to failure and there are different modes of failure. More often, the quantification of the dominating failure mode and the attendant prevailing fracture mechanism is an arduous task, even though this is of significant importance for the purposes of design. The deformation of a material can lead to any of three fracture mechanisms, which include: (a) elastic, leading to linear-elastic fracture mechanisms, (b) plastic, leading to elastic-plastic fracture mechanisms and (c) viscoelastic/visco-plastic, leading to creep fracture mechanisms. Failure behaviour of a material can be of three types, viz. (i) ductile, which can lead to either shear or dimple fracture, (ii) brittle which can lead to a cleavage fracture or a rupture and (iii) creep, which can lead to a creepfracture or normal/shear fracture. For fracture to occur, there must be some sort of material loading. Loading can be in the form of: (1) cyclic, leading to fatigue fracture, (2) static, leading to forced fracture, (3) dynamic, leading to fast fracture and (4) chemical, leading to stress corrosion cracking or fatigue corrosion cracking. These mechanisms and the different modes of fracture shall be discussed, in particular, for biocomposites and bionanocomposites, as these parameters (type of fracture mechanism, type of failure and type of loading) and, of course, the design protocols collectively determine the eventual performance of any material.
  • Item
    Open Access
    Polyhydroxyalkanoates as scaffolds for tissue engineering
    (Nova Publisher, 2018) Sadiku, E.R.; Fasiku, V.O.; Owonubi, S.J.; Mukwevho, E.; Aderibigbe, B.A.; Lemmer, Y.; Abbavaram, B.R.; Manjula, B.; Nkuna, C.; Dludlu, M.K.; Adeyeye, O.A.; Selatile, K.; Makgatho, G.; Ndamase, A.S.; Mabalane, P.N.; Agboola, O.; Sanni, S.; Varaprasad, K.; Tippabattini, J.; Kupolati, W.K.; Adeboje, A.O.; Jamiru, T.; Ibrahim, I.D.; Adekomaya, O.S.; Eze, A.A.; Dunne, R.; Areo, K.A.; Jayaramudu, J.; Daramola, O.O.; Periyar Selvam, S.; Nambiar, Reshma B.; Perumal, Anand B.; Mochane, M.J.; Mokhena, T.C.; Iheaturu, Nnamdi; Diwe, I.; Chima, Betty
    Tissue engineering is a field that has gained a lot of advancement since the discovery of biopolymers. Biopolymers are polymers produced by living organisms; that is, they are polymeric biomolecules. They consist of monomeric units that are covalently bonded to one another in order to form larger structures. Biopolymers have been widely used as biomaterials for the construction of tissue engineering scaffold. Scaffolds have been used for tissue engineering, such as: bone, cartilage, ligament, skin, vascular tissues, neural tissues, and skeletal muscles. Polyhydroxyester is a typical example of biopolymers that have been employed for this application. Their exceptional properties such as high surface-to-volume ratio, high porosity with very small pore size, biodegradation, and mechanical property have made them gain a lot of attention in this field. Also, they have advantages which are significant for tissue engineering. This chapter will focus on the production, modification, properties and medical applications of polyhydroxyesters, such as PLA (Polylactide), PGA (Polyglycolide or poly(glycolic acid)), PCL (Polycaprolactone), poly(ester amide)s and PLGA (Poly(lactide-co-glycolide), with particular emphasis on the different polyhydroxyalkanoates (PHAs), which have diverse applications in tissue engineering.