No description available.

No description available.

With the growing concern of the accumulation of plastic-based food packaging waste, the search for bio-based biodegradable packages is on the rise. These materials differ from their petro-based counterparts in their degradation rates, which are much higher in the former. Not only do bio-based biodegradable materials degrade faster during post-usage processes but also they age faster during usage and storage, which affects their performance and functionality. The application of noninvasive testing methods with the capability to report on the matrix’s state could assist in the development of a more ubiquitous way to assess ageing in food packaging, particularly in biodegradable ones. To this end, the performance of a luminescence spectroscopy technique based on three luminescent probes, one intrinsic to the matrix and two added, was monitored and the sensitivity of the probes to report on ageing was analyzed. Biodegradable films were made of 2% gelatin (type A) and 0.5% glycerol (plasticizer). Gelatin contains an intrinsic fluorophore, the aromatic amino acid tyrosine (Tyr), which can report on the molecular mobility of a matrix. Additionally, the films were doped with two extrinsic fluorophores, Fast Green FCF (FG) at 0.124 mM and pyranine (Pyr) at 0.05 mM, which can report on the physical state and available free water within a matrix, respectively. Films were casted onto plastic Petri dishes and stored at five relative humidities (RHs), namely 2.5, 25, 33, 53, and 75%, for five weeks with measurement collection every week. Films were tested using fluorescence spectroscopy at excitation and emission range wavelengths optimized depending on the assessed probe. Additional measurements to determine moisture content, changes in secondary protein structure using FTIR spectroscopy, and mechanical properties using a Universal Testing Machine in tensile mode aided in the evaluation of the sensitivity of the luminescent probes in sensing ageing. Luminescent probes, intrinsic or added, have the capability to assess the physical state of the films in situ and can provide molecular level sensing of their local environment. Tyr emission showed a sharp increase in fluorescence intensity in films stored at low RH as a function of time. FG showed a similar pattern to that of Tyr but higher sensitivity to changes along the observed period. The two characteristics emission bands of Pyr provide information on the state of water within the matrix. Although the results on this probe hinted microstructural rearrangements within the films as a function of time, the sensitivity of this probe was not high enough at the conditions evaluated and provided limited information on films’ solvation. The sensitivity of the luminescent probes to changes during ageing were revealed through correlation of the photophysical properties of the two effective probes, Tyr and FG, and the mechanical properties of the films at different RH through storage. Both methods, mechanical and optical, were similarly sensitive to changes during ageing particularly after 3-week storage. However,, it can be speculated that because of the different scales at which optical and mechanical measurements report (local vs. bulk), the methods, they could also complement each other. These findings suggest that, in principle, a luminescence spectroscopy technique using intrinsic and extrinsic probes can replace mechanical testing to noninvasively monitor structural changes and stability of biodegradable packaging as a function of time.

Yes / Binary and ternary blends of a polylactic acid matrix with polycaprolactone (PCL) and polybutylene succinate (PBS) were produced by twin screw extrusion, containing up to 30 wt% loading. Mechanical, thermal and rheological characterisation techniques were used to quantify properties of the different blend formulations and miscibility was investigated using scanning electron microscopy. PCL is known to act as an impact modifier in PLA but to cause a corresponding reduction in strength. Results showed that addition of both PBS and PCL seperatly caused a reduction in melt viscosity, elastic modulus and tensile strength, but an increase in impact strength and strain at break. Analysis of morphology suggested that immiscibility was evident, particularly at higher PCL and PBS loadings. Results indicated that incorporation of a small loading of PBS had a synergistic effect on the PLA-PCL blend properties. Miscibility was improved and enhanced mechanical properties were observed for a ternary blend containing 5 wt% of both PBS and PCL compared to blends containing 10% of each polymer alone. / Financial support of Floreon- Transforming Packaging Ltd through the PhD sponsorship and materials provision.

The fields of biotechnology and biomedical sciences are rapidly evolving and involve the constant growth of knowledge. As a consequence, engineering design has to also remain at the cutting edge in order to not inhibit the growth of these fields. This study focuses on engineering design and analysis as it pertains to the field of biotechnology, at every step of the engineering process. More specifically, how the engineering design and analysis approach can assist in solving medical problems relating to bone diseases and biomaterials. The first part of the study focuses on a project to design and manufacture a novel exosome isolation device, with the primary purpose of creating an affordable and accessible method of isolating exosomes for the testing and diagnosis processes in the Biomaterials & Nanoscience laboratory. The second part of the study focuses on the design and analysis of biodegradable bone implants, before, during, and after implantation. Together, these projects aim to show the engineering processes of design and analysis and serve to provide insight as to how engineering principles can be applied to the medical field.

Biodegradable implants continue to be of interest in orthopaedics for their many potential applications. The magnesium (Mg) alloy WE43 is a biodegradable material with the CE mark approval for clinical application and today mostly used as screws for dental prosthesis. Additional to magnesium, WE43 contains rare earth elements (REEs) of around 7 wt%. These REEs are needed to give the material its mechanical properties and corrosion resistance. Although WE43 is a promising material thought to be used in a diverse number of orthopaedical applications, questions have risen regarding the potential long-term effects of these REEs on the body after the implant degrades. Additionally, with the global demand of REEs rising and a decreasing supply of these elements, there may also be a potential future problem regarding the availability of materials based on REEs. Therefore, new materials containing only elements naturally found in the body are of interest. One such material is the novel Mg-Ca alloy, X0. In this study, a biological comparison was made to answer the question whether the biological performance of X0 is comparable to the already CE approved WE43. Viability, proliferation, and differentiation of MC3T3-E1 (preosteoblast) cells combined with extracts from X0 and WE43, respectively were used. An additional experiment was conducted were X0 was tested against three different versions of WE43 and titanium. In summary, the X0 alloy performed similarly to WE43 in all testing. Both WE43 and X0 showed indications of being bioactive. This led to the conclusion that the X0 alloy showed promise for future use and being a viable alternative to WE43.

Polylactic acid (PLA) is an aliphatic polyester, derived from sustainable natural sources that is biodegradable and can be industrially composted. This material has been in the spotlight recently due to its sustainability and properties. However it has been invented in 1932 by Carothers and then patented by DuPont in 1954 (Standau et al. 2019). The properties of this material though limit its use for applications mainly in the medical sector and in some cases single use packaging. In this research, PLA based blends with improved rheological and thermomechanical properties are investigated. The focus is based in proposing strategies in improving these properties based on commercial methods and processing techniques. In this work, commercial grade PLA has been blended with polycaprolactone (PCL) and polybutylene succinate (PBS) in binary and ternary formulations via twin screw extrusion. PCL has been known to act as an impact modifier for PLA, but to cause a corresponding reduction in strength. Results showed that the binary PLA blends containing PBS and PCL, had reduced viscosity, elastic modulus and strength, but increased strain at break and impact strength. Morphological and thermal analysis showed that the immiscibility of these additives with PLA caused these modifications. Incorporation of a small loading of PBS had a synergistic effect on the PLA-PCL blend properties. Miscibility was improved and enhanced mechanical properties were observed for a ternary blend containing 5wt% of both PBS and PCL compared to binary blends containing 10% of each additive. To increase heat resistance of PLA, the material’s crystallinity has to be increased. However PLA has a relatively slow crystallisation rate making it difficult and expensive to be used in commercial applications where heat resistance is needed. For this reason the chiral nature of PLA has been used to investigate the effect of stereochemistry of PLA in crystallisation. Optically pure PDLA was added to its enantiomer in small amounts (up to 15%) and the properties and crystallisation mechanism of these blends was investigated. Results showed that the addition of PDLA accelerated crystallinity and developed a stucture that increased heat resistance, melt strength and stiffness. Finally, a processing model of developing a fully stereocomplex PLA part based in commercial techniques is proposed. Injection moulded PLA showed even higher heat resistance without the need of further processing the product (increasing crystallinity). / Floreon

No description available.

No description available.

No description available.