Macromolecular Symposia最新文献

This study demonstrates that calcium carbonate derived from food waste (FW-CC) is a sustainable alternative to mineral CaCO₃ (G-CC), effectively enhancing the mechanical properties of polymer-based composites. The influence of chemical additives (polymeric dispersants and fatty acids) is analyzed to improve powder processability, dispersion, and filler-matrix adhesion. Additionally, the effect of FW-CC particle size on composite performance is assessed. Chemically treated FW-CaCO₃ is produced in an industrial facility, then mixed with the polymer matrix at 10% and 20%, and compared to those with untreated FW-CaCO₃ and traditional CaCO₃. Results confirm that FW-CC is a viable substitute for mineral CaCO₃, promoting sustainability by valorizing food waste and reducing dependence on non-renewable resources. These findings support further optimization and industrial applications in polymer composites.

Nowadays, the widespread use of composite materials is limited in some applications by their low delamination resistance and low damping ability. Thermoplastic and elastomeric nano- and micro-fibers have recently been proposed to enhance the fracture toughness of Carbon Fiber Reinforced Polymer (CFRP) laminates, yielding promising results. In the present work, the morphology of microfibrous electrospun membranes based on natural rubber/poly(lactic acid)/poly(ethylene oxide) (NR/PLA/PEO) polymer blends is investigated. It is observed that environmental parameters play a key role in determining the morphology of the fibers, allowing smooth and defect-free ones to be obtained at low humidity values while porous ones at high humidity values.

Breast prostheses are extensively employed for either aesthetic augmentation or medical aims. Clinical or subjective reasons may sometimes induce early removal; however, it is not uncommon for them to remain implanted for extended periods, often exceeding 20 years. Understanding the expected materials changes over time is crucial for deciding on their potential removal or replacement. This study examines the aging of silicone prosthesis materials, measuring the changes in the mechanical properties of the elastomeric shell and the viscosity of the inner gel after accelerated aging tests at various temperatures over a period exceeding two years. Predictive models based on the time-temperature superposition principle enable the estimation of mechanical performance over extended timeframes, providing valuable insights into the expected durability and lifespan of implants.

Epoxy diamine systems were thermally oxidized at 110°C under air. Ageing was monitored using DMA in multi-frequency multi-temperature mode. The analysis led to the conclusion that the crosslinking predominates. Data were exploited using classical VTFH and WLF theories for estimating the changes of free volume-related parameters with ageing.

Several factors still limit the achievement of effective mechanical recycling strategies for polyolefins. In particular, the thermo-mechanical degradation undergone during reprocessing, the different degradation forms experienced during the service life, as well as the cross-contaminations resulting from non-fully accurate sorting technologies, cause the obtainment of recyclates with heterogeneous microstructure, which significantly affect their final properties, often limiting their possible future applications. This study evaluates the combined effects of aging and cross-contamination for high-density polyethylene (HDPE) containing low amounts of polypropylene (PP) and polyethylene terephthalate (PET) as contaminants. HDPE systems were subjected to photo-oxidative or thermo-oxidative treatments and reprocessing to simulate real recycling scenarios. Results show that PP and PET contamination significantly reduce HDPE ductility under thermo-oxidative conditions, while exerting minimal impact on photo-oxidized materials.

Carbon fiber reinforced polymer (CFRP) laminates experienced a considerable diffusion in several application fields, especially where high specific mechanical properties are requested. While such materials are very versatile and contribute to obtaining lightweight and more “sustainable” structures, they potentially suffer from delamination, which poses an important limitation to their even more extensive widespread use. The integration of electrospun materials, especially nanofibers, is a smart solution to reduce such a phenomenon. The present work aims to compare different fibrous and nanofibrous systems that are able to contrast delamination by increasing interlaminar fracture toughness. In particular, the reinforcing effect delivered by electrospun veils made of Nylon 66, Nylon 66 coated with nitrile butadiene rubber (NBR), rubber-containing blends (NBR with polycaprolactone, PCL, or with Nomex), and a commercial thermosetting polymer is disclosed.

As a result of the conducted research, rigid polyurethane-polyisocyanurate foams (PUR/PIR) with enhanced flame resistance and biocidal functionality were developed. The flame retardancy was achieved by incorporating a novel type of halogen-free flame retardant. Resistance to fungi and bacteria was conferred through the use of a proprietary hybrid biocidal additive (HBA). Such rigid polyurethane-polyisocyanurate foams are suitable for use as insulation materials in modular construction applications.

Dust poses a significant threat to any equipment operating on the Moon, particularly for long-term explorations. The development of efficient dust mitigation solutions is therefore critical for the success of lunar missions. In this work, fully aromatic and fluorinated polyimide (PI) and poly(imide-dimethylsiloxane) (PIDMS) copolymers are synthesized. The surface properties of the PIDMS materials are investigated using several techniques to evaluate their potential application as materials with lunar dust mitigation properties. In particular, the top and bottom surfaces are analyzed using Fourier transform infrared spectroscopy and a wettability study to assess the preferential segregation of the siloxane chains toward one or the other side. Thermal analysis from differential scanning calorimetry suggests that the copolymer materials can withstand the harsh conditions of the Moon's surface. Morphology analysis by scanning electron microscopy shows an increase in surface roughness upon addition of the siloxane segments.

Electrospun nanofibrous coatings based on poly(lactic acid) (PLA) and bioactive nano-hydroxyapatite (nHAp) are developed to enhance the biocompatibility and corrosion resistance of titanium implants for medical applications. The electrospinning process parameters are optimized to achieve a uniform morphology of PLA nanofibers and PLA/nHAp composite fibers. The morphology and porosity of the fiber coatings were investigated by scanning electron microscopy. FTIR spectroscopy confirms the successful incorporation of nHAp into the PLA fibers, while electrochemical impedance spectroscopy demonstrates a significant improvement in corrosion resistance for the nanocomposite-coated titanium. Results show that the PLA/nHAp composite coatings prepared by electrospinning have promising features for applications in orthopedic and dental implantology.

Carbon capture, utilization, and storage is a crucial short-term strategy to mitigate climate change. Once captured, CO₂ needs to be transported to storage sites, and to ensure efficient transport, it is typically compressed into a liquid or supercritical fluid. These conditions can alter the properties of materials used during the transport stage. A HNBR, a commonly used elastomer in oil and gas applications, is investigated in this work in terms of its CO₂ permeation properties. The plasticization effect of CO₂ plays a key role, as it can shift the glass transition temperature, leading to peculiar permeability behavior at high-pressure. Thermodynamic modelling is also effectively applied, describing the observed trends.