Constitutive modeling of biodegradable polymers: Hydrolytic degradation and time-dependent behavior

Vieira, André Costa; Guedes, Rui Miranda; Tita, Volnei

doi:10.1016/j.ijsolstr.2013.12.010

Cited by 49 publications

(50 citation statements)

References 52 publications

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“…A number of models have been presented to predict the mechanical properties of degradable polymers (Hayman et al, 2014;Soares et al, 2010;Vieira et al, 2014;Vieira et al, 2011;Wang et al, 2010). A model was developed by Vieira et al (2014) based on the relationship between fracture strength and molecular weight for thermoplastic polymers to predict the mechanical properties of PLA-PCL fibers during degradation.…”

Section: Introductionmentioning

confidence: 99%

Modelling the degradation and elastic properties of poly(lactic-co-glycolic acid) films and regular open-cell tissue engineering scaffolds

Shirazi

Ronan

Rochev

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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Publication InformationShirazi, RN,Ronan, W,Rochev, Y,McHugh, P (2016) 'Modelling the degradation and elastic properties of poly (lacticco-glycolic AbstractScaffolding plays a critical rule in tissue engineering and an appropriate degradation rate and sufficient mechanical integrity are required during degradation and healing of tissue. This paper presents a computational investigation of the molecular weight degradation and the mechanical performance of poly(lactic-co-glycolic acid) (PLGA) films and tissue engineering scaffolds. A reactiondiffusion model which predicts the degradation behaviour is coupled with an entropy-based mechanical model which relates the Young's modulus and the molecular weight. The model parameters are determined based on experimental data for in-vitro degradation of a PLGA film. Microstructural models of three different scaffold architectures are used to investigate the degradation and mechanical behaviour of each scaffold. Although the architecture of the scaffold does not have a significant influence on the degradation rate, it determines the initial stiffness of the scaffold. It is revealed that the size of the scaffold strut controls the degradation rate and the mechanical collapse. A critical length scale due to competition between diffusion of degradation products and autocatalytic degradation is determined to be in the range 2-100 μm. Below this range, slower homogenous degradation occurs; however, for larger samples monomers are trapped inside the sample and faster autocatalytic degradation occurs.

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Section: Introductionmentioning

confidence: 99%

Modelling the degradation and elastic properties of poly(lactic-co-glycolic acid) films and regular open-cell tissue engineering scaffolds

Shirazi

Ronan

Rochev

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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“…The main limitation of the proposed constitutive model is that it does not explicitly capture the inelastic behaviour of the scaffold in terms of water-induced degradation (Soares et al, 2007;Soares et al, 2010c;Soares and Zunino, 2010b;Vieira et al, 2011), viscoelastic (Muliana andRajagopal, 2012a) and viscoplastic behaviour (Khan and ElSayed, 2013;Vieira et al, 2014) and mechanical damage due to excessive loading (Soares, 2008). Such features will no doubt augment the fidelity of the material modelling and increase predictive capabilities by providing a mechanistic link between degradation time and resulting altered mechanical properties.…”

Section: Discussionmentioning

confidence: 99%

“…The transversely isotropic 8-chain conformation would remain identical in terms of kinematics. Alternatively, one could use the model proposed by Vieira et al (2014) and extend it to transverse isotropy by introducing a second characteristic dimension in the unit cell of the 8-chain model (Bischoff et al, 2002b, c;Kuhl et al, 2005). Instead of using a chain energy based on entropic elasticity (defined by configurational entropy rather than internal energy) of macromolecules one could also adopt a similar ansatz to what is proposed in our model, namely a bimodal Knowles strain energy function (null in compression along the fibre direction).…”

Section: Discussionmentioning

confidence: 99%

“…Structures made of biodegradable polymers generally are subjected to strain rate-sensitive cyclic loads sufficient to induce large elastic and/or inelastic strains operating in the non-linear regime (Grabow et al, 2013;Vieira et al, 2014;Vieira et al, 2013). It is therefore important to consider constitutive models that, depending on particular applications, can capture specific features such as large deformations.…”

Section: Introductionmentioning

confidence: 99%

“…Khan and El-Sayed (2013) derived a non-linear viscohyperelastic formulation based on conservative and dissipative potentials which also accounted for deformation-induced degradation following the work of Soares (2008). Recently, Vieira et al (2014) proposed what probably is the most advanced 3D continuum constitutive model for biodegradable polymers with regards to the purely mechanical behaviour. The constitutive behaviour is based on the micromechanically-based strain rate-dependent Bergström-Boyce formulation for polymers (Bergstrom and Boyce, 1998).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The anisotropic mechanical behaviour of electro-spun biodegradable polymer scaffolds: Experimental characterisation and constitutive formulation

Limbert

Omar

Krynauw

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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Electro-spun biodegradable polymer fibrous structures exhibit anisotropic mechanical properties dependent on the degree of fibre alignment. Degradation and mechanical anisotropy need to be captured in a constitutive formulation when computational modelling is used in the development and design optimisation of such scaffolds. Biodegradable polyester-urethane scaffolds were electro-spun and underwent uniaxial tensile testing in and transverse to the direction of predominant fibre alignment before and after in vitro degradation of up to 28 days. A microstructurally-based transversely isotropic hyperelastic continuum constitutive formulation was developed and its parameters were identified from the experimental stress-strain data of the scaffolds at various stages of degradation. During scaffold degradation, maximum stress and strain in circumferential direction decreased from 1.02±0.23 MPa to 0.38±0.004 MPa and from 46±11% to 12±2%, respectively. In longitudinal direction, maximum stress and strain decreased from 0.071±0.016 MPa to 0.010±0.007 MPa and from 69±24% to 8±2%, respectively. The constitutive parameters were identified for both directions of the non-degraded and degraded scaffold for strain range varying between 0% and 16% with coefficients of determination r 2 > 0.871. The six-parameter constitutive formulation proved versatile enough to capture the varying non-linear transversely isotropic behaviour of the fibrous scaffold throughout various stages of degradation.

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A Biopolymer Derived from Castor Oil Polyurethane: Experimental and Numerical Analyses

Costa

Vieira

Guedes

et al. 2017

Handbook of Composites From Renewable Materials

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Constitutive modeling of biodegradable polymers: Hydrolytic degradation and time-dependent behavior

Cited by 49 publications

References 52 publications

Modelling the degradation and elastic properties of poly(lactic-co-glycolic acid) films and regular open-cell tissue engineering scaffolds

Modelling the degradation and elastic properties of poly(lactic-co-glycolic acid) films and regular open-cell tissue engineering scaffolds

The anisotropic mechanical behaviour of electro-spun biodegradable polymer scaffolds: Experimental characterisation and constitutive formulation

A Biopolymer Derived from Castor Oil Polyurethane: Experimental and Numerical Analyses

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