Kinetics Of Polymer Degradation Research Articles

Bioactive glass-polymer nanocomposites: a comprehensive review on unveiling their biomedical applications.

Most natural and synthetic polymers are promising materials for biomedical applications because of their biocompatibility, abundant availability, and biodegradability. Their properties can be tailored according to the intended application by fabricating composites with other polymers or ceramics. The incorporation of ceramic nanoparticles such as bioactive glass (BG) and hydroxyapatite aids in the improvement of mechanical and biological characteristics and alters the degradation kinetics of polymers. BG can be used in the form of nanoparticles, nanofibers, scaffolds, pastes, hydrogels, or coatings and is significantly employed in different applications. This biomaterial is highly preferred because of its excellent biocompatibility, bone-stimulating activity, and favourable mechanical and degradation characteristics. Different compositions of nano BG are incorporated into the polymer system and studied for positive results such as enhanced bioactivity, better cell adherence, and proliferation rate. This review summarizes the fabrication and the progress of natural/synthetic polymer-nano BG systems for biomedical applications such as drug delivery, wound healing, and tissue engineering. The challenges and the future perspectives of the composite system are also addressed.

Mechanochemical Reactivity of a 1,2,4-Triazoline-3,5-dione-Anthracene Diels-Alder Adduct.

Force-responsive molecules that produce fluorescent moieties under stress provide a means for stress-sensing and material damage assessment. In this work, we report a mechanophore based on Diels-Alder adduct TAD-An of 4,4'-(4,4'-diphenylmethylene)-bis-(1,2,4-triazoline-3,5-dione) and initiator-substituted anthracene that can undergo retro-Diels-Alder (rDA) reaction by pulsed ultrasonication and compressive activation in bulk materials. The influence of having C-N versus C-C bonds at the sites of bond scission is elucidated by comparing the relative mechanical strength of TAD-An to another Diels-Alder adduct MAL-An obtained from maleimide and anthracene. The susceptibility to undergo rDa reaction correlates well with bond energy, such that C-N bond containing TAD-An degrades faster C-C bond containing MAL-An because C-N bond is weaker than C-C bond. Specifically, the results from polymer degradation kinetics under pulsed ultrasonication shows that polymer containing TAD-An has a rate constant of 1.59×10-5 min-1 , while MAL-An (C-C bond) has a rate constant of 1.40×10-5 min-1 . Incorporation of TAD-An in a crosslinked polymer network demonstrates the feasibility to utilize TAD-An as an alternative force-responsive probe to visualize mechanical damage where fluorescence can be "turned-on" due to force-accelerated retro-Diels-Alder reaction.

An on-demand bioresorbable neurostimulator

Bioresorbable bioelectronics, with their natural degradation properties, hold significant potential to eliminate the need for surgical removal. Despite notable achievements, two major challenges hinder their practical application in medical settings. First, they necessitate sustainable energy solutions with biodegradable components via biosafe powering mechanisms. More importantly, reliability in their function is undermined by unpredictable device lifetimes due to the complex polymer degradation kinetics. Here, we propose an on-demand bioresorbable neurostimulator to address these issues, thus allowing for clinical operations to be manipulated using biosafe ultrasound sources. Our ultrasound-mediated transient mechanism enables (1) electrical stimulation through transcutaneous ultrasound-driven triboelectricity and (2) rapid device elimination using high-intensity ultrasound without adverse health effects. Furthermore, we perform neurophysiological analyses to show that our neurostimulator provides therapeutic benefits for both compression peripheral nerve injury and hereditary peripheral neuropathy. We anticipate that the on-demand bioresorbable neurostimulator will prove useful in the development of medical implants to treat peripheral neuropathy.

Review of qualification and modeling for radiation-induced polymer degradation

Polymeric materials have multiple potential applications in nuclear power reactors including advanced and small modulus reactors, in addition to their extensive usage in safety electronic cables in the existing light water reactors. Through the qualification programs, knowledge accumulates about the polymer degradation kinetics under gamma-irradiation environment to facilitate the development of service-life predictive models. This paper aims to promote mechanistic-based predictability as a new approach to the qualification of polymeric components. Reviewed in this article are the current qualification standards and procedures, the current understandings of the degradation mechanisms, and kinetic models applicable to accelerated experiments for qualification.

Model-based optimization of drug release rate from a size distributed population of biodegradable polymer carriers

In the present study, a comprehensive polymer degradation-drug diffusion model is developed to describe the polymer degradation kinetics and quantify the release rate of an active pharmaceutical ingredient (API) from a size-distributed population of drug-loaded poly(lactic-co-glycolic) acid (PLGA) carriers in terms of material and morphological properties of the drug carriers. To take into account the spatial–temporal variation of the drug and water diffusion coefficients, three new correlations are developed in terms of spatial–temporal variation of the molecular weight of the degrading polymer chains. The first one relates the diffusion coefficients with the time-spatial variation of the molecular weight of PLGA and initial drug loading and, the second one with the initial particle size, and the third one with evolution of the particle porosity due to polymer degradation. The derived model, comprising a system of partial differential and algebraic equations, is numerically solved using the method of lines and validated against published experimental data on the drug release rate from a size distributed population of piroxicam-PLGA microspheres. Finally, a multi-parametric optimization problem is formulated to calculate the optimal particle size and drug loading distributions of drug-loaded PLGA carriers to realize a desired zero-order drug release rate of a therapeutic drug over a specified administration period of several weeks. It is envisaged that the proposed model-based optimization approach will aid the optimal design of new controlled drug delivery systems and, consequently, the therapeutic outcome of an administered drug.

Degradation kinetics of synthetic acrylamide polymers as a viscosity and filtration control additives in the low-density water – Based drilling fluid systems

The impact of synthetic polymers in water-based drilling fluids (WBDFs) along with other functional additives is a critical task to ensure wellbore stability. In this regard, three different synthetic acrylamide polymers with various degrees of sulfonation–DoS (0–30%) and molecular weight of ≈2.8–3 million DU were investigated. The sulfonic substitution was verified using NMR techniques. The thermal-stability of these polymers was quantitatively investigated using a reliable titration technique.The quantified time-temperature kinetics of polymer degradation was correlated with their respective performance in low-density WBDFs in terms of filtration and viscosity. The WBDFs were formulated using NaCl brine, synthetic polymers, bentonite and other additives. The WBDFs were hot rolled at 250 °F and 350 °F for 16 h and the viscosity and filtration control was determined.The WBDFs investigation showed that the three polymers maintained desired viscosity (AV: 35–65 cp) and reasonable filtration control (<15 ml) for the fresh and aged fluids up to 250 °F. However, at elevated temperatures, the filtration performance at 350 °F got deteriorated. The present work, for the first time, explains this impact of temperature on the WBDF performance on the basis of time-temperature kinetics of polymer degradation. It was also noted that at the elevated temperature of 350 °F, moderately sulfonated polymer (DoS = 15%) had shown significantly better filtration control and viscosity compared to the other polymers as evident from both viscosity and filtration tests. The optimum performance of the polymer with moderate sulfonation was explained using a novel approach as a competing effect of two distinct mechanisms: variation in activation energy parameter of polymer degradation rate and change in polymer length with increasing degrees of substitution. The insights gained on the time-temperature dynamics of the polymer stability in the present work could also be utilized for devising the polymer replenishment strategy for the drilling automation processes.

Late Catch-up In-Stent Restenosis and Stent Thrombosis for 2nd Generation Biodegradable Polymer Drug Eluting Stents

Second generation drug-eluting stents (DES) have reduced the rate of in-stent restenosis (ISR) to &lt; 10% [1, 2] in patients undergoing PCI. However, late catch-up in-stent restenosis remains an issue despite the advent in drug-eluting stent technology from 1st to 2nd generation drug eluting stents. The late catch-up phenomenon has been associated with serious consequences and adverse events and remains an important issue in modern practice, despite medical advances with more biocompatible and biodegradable polymers, as well as new therapeutic agents and thinner scaffolds in the development of 2nd generation DES polymer systems. The idea behind biodegradable polymers has been to provide a more controlled elution profile for DES drugs, allowing for long-term therapeutic, but sub-toxic, drug levels in the arterial tissue to prevent ISR and stent thrombosis. However, the late catch-up phenomenon remains an issue resulting in 2ndary revascularization beyond the first year of primary PCI, as it is defined as ISR &gt;1 year. Late stent thrombosis (&lt;1 year) and very late stent thrombosis (&gt;1 year) also remain an issue for biodegradable polymer systems. A long-term presence of the polymer can cause inflammation and thrombogenesis, which is dependent upon polymer degradation kinetics in case of biodegradable polymer DES systems. However, the cause of late catch-up restenosis and stent thrombosis is multi-factorial from a drug-in-polymer formulation perspective of drug release kinetics, e.g., drug elution profile, drug physiochemical properties, and polymer degradation kinetics. It appears that the focus should be on controlling burst release for both late catch-up restenosis and stent thrombosis phenomena.

Antimicrobial Polymeric Composites with Embedded Nanotextured Magnesium Oxide

Nanotextured magnesium oxide (MgO) can exhibit both antibacterial and tissue regeneration activity, which makes it very useful for implant protection. To successfully combine these two properties, MgO needs to be processed within an appropriate carrier system that can keep MgO surface available for interactions with cells, slow down the conversion of MgO to the less active hydroxide and control MgO solubility. Here we present new composites with nanotextured MgO microrods embedded in different biodegradable polymer matrixes: poly-lactide-co-glycolide (PLGA), poly-lactide (PLA) and polycaprolactone (PCL). Relative to their hydrophilicity, polarity and degradability, the matrices were able to affect and control the structural and functional properties of the resulting composites in different manners. We found PLGA matrix the most effective in performing this task. The application of the nanotextured 1D morphology and the appropriate balancing of MgO/PLGA interphase interactions with optimal polymer degradation kinetics resulted in superior bactericidal activity of the composites against either planktonic E. coli or sessile S. epidermidis, S. aureus (multidrug resistant-MRSA) and three clinical strains isolated from implant-associated infections (S. aureus, E. coli and P. aeruginosa), while ensuring controllable release of magnesium ions and showing no harmful effects on red blood cells.

The interplay between network morphology and degradation kinetics of polymers: Theoretical and experimental analysis by means of a 2D model system

ABSTRACTNetwork formation by cross-linking is a common method to incorporate functions like elastic deformability, shape-memory capability or hydrogel formation into polymer materials for medical applications. Since these materials are often intended to degrade, their design would benefit from a quantitative prediction of the interdependence between network architecture and degradation behavior. Here, we introduce a quantitative description of the degradation behavior of polymer networks. A simplified model was developed under the assumption of having an ideal network, where all network strands are terminated by network nodes and each node is connected to the same number of strands. To describe the degradation of real networks, the model was modified by allowing for a varying connectivity of network nodes, which also included free chain-ends. The models were validated by comparison with Langmuir monolayer degradation data from 2D networks formed by cross-linking oligo(ε-caprolactone)diols with dialdehydes. We found that both the ideal network hypothesis and the real network model were in excellent agreement with the experimental data, with the ideal network hypothesis requiring longer network strands than the real network to result in the same degradation behavior. The models were further used to calculate the degradation curves of the corresponding, non cross-linked molecules. By comparison, it was found that the network formation increases the time required to reach 50% degradation of oligo(ε-caprolactone)diols by only 20%. This difference mainly arises from attaching free chain ends to network points.

Physics-based prediction of biopolymer degradation.

In the natural environment, insoluble biomatter provides a preeminent source of carbon for bacteria. Its degradation by microbial communities thus plays a major role in the global carbon-cycle. The prediction of degradation processes and their sensitivity to changes in environmental conditions can therefore provide critical insights into globally occurring environmental adaptations. To elucidate and quantify this macro-scale phenomenon, we conduct micro-scale experiments that examine the degradation of isolated biopolymer particles and observe highly nonlinear degradation kinetics. Since conventional scaling arguments fail to explain these observations, it is inferred that the coupled influence of both the physical and biochemical processes must be considered. Hence, we develop a theoretical model that accounts for the bio-chemo-mechanically coupled kinetics of polymer degradation, by considering the production of bio-degraders and their ability to both dissociate the material from its external boundaries and to penetrate it to degrade its internal mechanical properties. This change in mechanical properties combined with the intake of solvent or moisture from the environment leads to chemo-mechanically coupled swelling of the material and, in-turn, influences the degradation kinetics. We show that the model quantitatively captures our experimental results and reveals distinct signatures of different bacteria that are independent of the specific experimental conditions (i.e. particle volume and initial concentrations). Finally, after validating our model against the experimental data we extend our predictions for degradation processes across various length and time scales that are inaccessible in a laboratory setting.

High temperature polymer degradation: Rapid IR flow-through method for volatile quantification

Accelerated aging of polymers at elevated temperatures often involves the generation of volatiles. These can be formed as the products of oxidative degradation reactions or intrinsic pyrolytic decomposition as part of polymer scission reactions. A simple analytical method for the quantification of water, CO2, and CO as fundamental signatures of degradation kinetics is required. This study describes an analytical framework and develops a rapid mid-IR based gas analysis methodology to quantify volatiles that are contained in small ampoules after aging exposures. The approach requires identification of unique spectral signatures, systematic calibration with known concentrations of volatiles, and a rapid acquisition FTIR spectrometer for time resolved successive spectra. The volatiles are flushed out from the ampoule with dry N2 carrier gas and are then quantified through spectral and time integration. This method is sufficiently sensitive to determine absolute yields of ∼50 μg water or CO2, which relates to probing mass losses of less than 0.01% for a 1 g sample, i.e. the early stages in the degradation process. Such quantitative gas analysis is not easily achieved with other approaches. This approach opens up the possibility of quantitative monitoring of volatile evolution as an avenue to explore polymer degradation kinetics and its dependence on time and temperature.

Ultrasonic degradation kinetics and rheological profiles of a food polysaccharide (konjac glucomannan) in water

This study was carried out to evaluate the effects of power ultrasound (US) on the molecular weight and rheological properties of a food polysaccharide, konjac glucomannan (KGM). Upon the exposure of KGM solution (1% w/v in water) to US at a relatively high power intensity (50 W/cm2), the apparent viscosity decreased rapidly from about 50 Pa s to a negligible level within 10–20 min. The intrinsic viscosity ([η]) of KGM solution decreased gradually during the US exposure with a time course closely fitted to the first-order polymer degradation kinetics (random chain scission). The US treatment also caused a significant reduction of particle size (Zavg) of KGM aggregates and changes in the rheological properties including the decrease of storage modulus (G′) and loss modulus (G″), and the increase in phase angle (tan δ = G″/G′). Nevertheless, no change in primary structure was detected by Fourier transformation infrared (FT-IR) analysis. The results suggested that high intensity US was an effective means for KGM degradation without significant structural destruction.

Meta-Analysis of Randomized Clinical Trials Comparing Biodegradable Polymer Drug-Eluting Stent to Second-Generation Durable Polymer Drug-Eluting Stents

ObjectivesThe authors sought to perform a meta-analysis of randomized clinical trials (RCTs) comparing the safety and efficacy of biodegradable polymer drug-eluting stents (BP-DES) to second-generation durable polymer drug-eluting stents (DP-DES). BackgroundPrior meta-analyses have established the superiority of BP-DES over bare-metal stents and first-generation DP-DES; however, their advantage compared with second-generation DP-DES remains controversial. MethodsThe authors searched PubMed and Scopus databases for RCTs comparing BP-DES to the second-generation DP-DES. Outcomes included target vessel revascularization (TVR) as efficacy outcome and cardiac death, myocardial infarction (MI), and definite or probable stent thrombosis (ST) as safety outcomes. In addition, we performed landmark analysis for endpoints beyond 1 year of follow-up and a subgroup analysis based on the stent characteristics. ResultsThe authors included 16 RCTs comprising 19,886 patients in the meta-analysis. At the longest available follow-up (mean duration 26 months), we observed no significant differences in TVR (p = 0.62), cardiac death (p = 0.46), MI (p = 0.98), or ST (risk ratio: 0.83, 95% confidence interval: 0.64 to 1.09; p = 0.19). Our landmark analysis showed that BP-DES were not associated with a reduction in the risk of very late ST (risk ratio: 0.87, 95% confidence interval: 0.49 to 1.53; p = 0.62). Similar outcomes were seen regardless of the eluting drug (biolimus vs. sirolimus), the stent platform (stainless steel vs. alloy), the kinetics of polymer degradation or drug release (<6 months vs. >6 months), the strut thickness of the BP-DES (thin <100 μm vs. thick >100 μm), or the DAPT duration (≥6 months vs. ≥12 months). ConclusionsBP-DES have similar safety and efficacy profiles to second-generation DP-DES.

Poly(3-hydroxybutyrate)/metribuzin formulations: characterization, controlled release properties, herbicidal activity, and effect on soil microorganisms.

Slow-release formulations of the herbicide metribuzin (MET) embedded in the polymer matrix of degradable poly-3-hydroxybutyrate [P(3HB)] in the form of microparticles, films, microgranules, and pellets were developed and tested. The kinetics of polymer degradation, MET release, and accumulation in soil were studied in laboratory soil microecosystems with higher plants. The study shows that MET release can be controlled by using different techniques of constructing formulations and by varying MET loading. MET accumulation in soil occurs gradually, as the polymer is degraded. The average P(3HB) degradation rates were determined by the geometry of the formulation, reaching 0.17, 0.12, 0.04, and 0.05mg/day after 60days for microparticles, films, microgranules, and pellets, respectively. The herbicidal activities of P(3HB)/MET formulations and commercial formulation Sencor Ultra were tested on the Agrostis stolonifera and Setaria macrocheata plants. The parameters used to evaluate the herbicidal activity were plant density and the weight of fresh green biomass measured at days 10, 20, and 30 after sowing. All P(3HB)/MET formulations had pronounced herbicidal activity, which varied depending on MET loading and the stage of the experiment. In the early phases of the experiment, the herbicidal effect of P(3HB)/MET formulations with the lowest MET loading (10%) was comparable with that of the commercial formulation. The herbicidal effect of P(3HB)/MET formulations with higher MET loadings (25 and 50%) at later stages of the experiment were stronger than the effect of Sencor Ultra.

MO‐AB‐BRA‐02: Modeling Nanoparticle‐Eluting Spacer Degradation During Brachytherapy Application with in Situ Dose‐Painting

Purpose:Brachytherapy application with in situ dose‐painting using gold nanoparticles (GNP) released from GNP‐loaded brachytherapy spacers has been proposed as an innovative approach to increase therapeutic efficacy during brachytherapy. This work investigates the dosimetric impact of slow versus burst release of GNP from next generation biodegradable spacers.Methods:Mathematical models were developed based on experimental data to study the release of GNP from a spacer designed with FDA approved poly(lactic‐co‐glycolic acid) (PLGA) polymer. The diffusion controlled released process and PLGA polymer degradation kinetics was incorporated in the calculations for the first time. An in vivo determined diffusion coefficient was used for determining the concentration profiles and corresponding dose enhancement based on initial GNP‐loading concentrations of 7 mg/g.Results:The results showed that there is significant delay before the concentration profile of GNP diffusion in the tumor is similar to that when burst release is assumed as in previous studies. For example, in the case of burst release after spacer administration, it took up to 25 days for all the GNP to be released from the spacer using diffusion controlled release process only. However, it took up to 45 days when a combined model for both diffusion and polymer degradation processes was used. Based on the tumor concentration profiles, a significant dose enhancement factor (DEF &gt;20%), could be attained at a tumor distances of 5 mm from a spacer loaded with 10 nm GNP sizes.Conclusion:The results highlight the need to take the slow release of GNP from spacers and factors such as biodegradation of polymers into account in research development of GNP‐eluting spacers for brachytherapy applications with in‐situ dose‐painting using gold nanoparticles. The findings suggest that I‐125 may be the more appropriate for such applications given the relatively longer half‐live compared to other radioisotopes like Pd‐103 and Cs‐131.

QCM-based measurement of chlorine-induced polymer degradation kinetics.

Highly structured network polymers are prepared via a molecular layer by layer technique (mLbL) and used as a model system to study aqueous degradation of polymer thin films in real time. Quantitative analysis of the degradation kinetics was enabled by the use of a quartz crystal microbalance (QCM). We conclude that the common metric of halogen, specifically chlorine, exposure (concentration × time) to be an ineffective normalization unit and showed a multistage adsorption process consistent with the established chemical mechanism. Additionally, degradation progression was tracked at multiple points of exposure to determine the effects of chlorination on the chemical and morphological state of the polymer structure with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. The formation of known halogenation products were corroborated with XPS through the high resolution spectra. Insight into the heterogeneous nature of the nanostructural degradation was derived from the AFM images. Periodic rinsing was found to release adsorbed chlorine but had negligible benefits on extending the exposure limits of the polyamide film. Fluorinated amine monomer (3,4-difluoroaniline) was incorporated into the surface of the polymer to determine the effect of limiting N-halogenation and the formation of the halogenated ring product. The modified surface layer reduced the rate and magnitude of chlorine adsorption relative to the neat polyamide surface. The QCM technique was shown to be an effective tool for rapid and high fidelity evaluation of molecular degradation and modification strategies to increase device lifetimes.

Enzymatic degradation of polymers: a brief review

Recently, research on polymer has drawn much attention mainly due to the ever increasing application of these polymeric materials in several areas such as food packaging industry, agricultural industry and biomedical research. However, increasing industrial use of polymers has led to the environmentally critical issue of waste disposal. Further, the successful implication of polymeric materials in biomedical applications depends on the biodegradability of the concerned polymer. Various enzymes play an important role in the biodegradation of polymers. The present review describes the enzyme mediated biodegradation of various polymers including synthetic, natural and blends of these materials. Detailed examples of enzymatic degradation of polymers are illustrated from current scientific literature with the discussion on various factors that can influence the degradation. In addition, different techniques that are generally applied to assess the degradation process as well as degradation products have been described. Finally, a special emphasis is given to the investigation of the kinetics of polymer degradation by enzymes.

Degradation of thin poly(lactic acid) films: Characterization by capacitance–voltage, atomic force microscopy, scanning electron microscopy and contact-angle measurements

For the development of new biopolymers and implantable biomedical devices with predicted biodegradability, simple, non-destructive, fast and inexpensive techniques capable for real-time in situ testing of the degradation kinetics of polymers are highly appreciated. In this work, a capacitive field-effect electrolyte–insulator–semiconductor (EIS) sensor has been applied for real-time in situ monitoring of degradation of thin poly(d,l-lactic acid) (PDLLA) films over a long-time period of one month. Generally, the polymer-modified EIS (PMEIS) sensor is capable of detecting any changes in the bulk, surface and interface properties of the polymer (e.g., thickness, coverage, dielectric constant, surface potential) induced by degradation processes. The time-dependent capacitance–voltage (C–V) characteristics of PMEIS structures were used as an indicator of the polymer degradation. To accelerate the PDLLA degradation, experiments were performed in alkaline buffer solution of pH 10.6. The results of these degradation measurements with the EIS sensor were verified by the detection of lactic acid (product of the PDLLA degradation) in the degradation medium. In addition, the micro-structural and morphological changes of the polymer surface induced by the polymer degradation have been systematically studied by means of scanning-electron microscopy, atomic-force microscopy, optical microscopy, and contact-angle measurements.

Effect of drug loading and laser surface melting on drug release profile from biodegradable polymer

ABSTRACTThe biodegradable polymer such as poly(l‐lactic acid) is promising in drug delivery applications because it allows for drug release in a controlled manner. In a polymer‐based drug delivery system, drug release is controlled by polymer degradation and drug loading concentration. In this study, effect of drug concentration on drug release profile is investigated through polymer crystallinity, chain mobility, and polymer degradation, as characterized by the wide‐angle X‐ray diffraction, differential scanning calorimetry, and gel permeation chromatography, respectively. The addition of drug has been shown to accelerate polymer degradation and drug release rate. With a low drug concentration, the slow polymer degradation kinetics results in an induction period of drug release, during which a limited amount of drug is released. The induction period is undesirable because it delays drug release and effectiveness. Since drug release is controlled by polymer degradation, which is a function of polymer crystallinity, laser surface melting is conducted to reduce polymer surface crystallinity and modify its degradation. The effect of laser crystallinity modification on drug release is investigated. A numerical model is also implemented based on hydrolysis and diffusion mechanisms to investigate the effects of drug loading and laser surface melting on polymer degradation and drug release process. It has been demonstrated that laser treatment shortens the induction period of drug release while keeps the release rate unmodified, as desired in drug delivery applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4147–4156, 2013

Understanding mild acid pretreatment of sugarcane bagasse through particle scale modeling

Sugarcane bagasse is an abundant and sustainable resource, generated as a by-product of sugarcane milling. The cellulosic material within bagasse can be broken down into glucose molecules and fermented to produce ethanol, making it a promising feedstock for biofuel production. Mild acid pretreatment hydrolyses the hemicellulosic component of biomass, thus allowing enzymes greater access to the cellulosic substrate during saccharification. A particle-scale mathematical model describing the mild acid pretreatment of sugarcane bagasse has been developed, using a volume averaged framework. Discrete population-balance equations are used to characterise the polymer degradation kinetics, and diffusive effects account for mass transport within the cell wall of the bagasse. As the fibrous material hydrolyses over time, variations in the porosity of the cell wall and the downstream effects on the reaction kinetics are accounted for using conservation of volume arguments. Non-dimensionalization of the model equations reduces the number of parameters in the system to a set of four dimensionless ratios that compare the timescales of different reaction and diffusion events. Theoretical yield curves are compared to macroscopic experimental observations from the literature and inferences are made as to constraints on these "unknown" parameters. These results enable connections to be made between experimental data and the underlying thermodynamics of acid pretreatment. Consequently, the results suggest that data-fitting techniques used to obtain kinetic parameters should be carefully applied, with prudent consideration given to the chemical and physiological processes being modeled.