Multi-stage, in-situ polymerisation for low-exotherm, liquid resin infusion of thick thermoplastic laminates at room temperature

This study exploits the unique attributes of a reactive thermoplastic acrylic resin system (room-temperature liquid-resin infusibility, in-situ polymerisability, and room-temperature weldability) to achieve additive-free mitigation of exothermic heat generation during thick laminate production. Additives are typically required when thicknesses exceed 12 mm, but their use often compromises the degree of polymerisation and mechanical performance. An innovative multi-stage manufacturing scheme has been used to achieve a 55 °C reduction in exothermic peak temperature during the production of a 16-mm-thick laminate compared to the use of a standard resin infusion (89 °C) for the same thickness. Laminates produced using the multi-stage scheme were also found to exhibit 24 % higher short-beam shear strengths than those obtained via standard resin infusion, suggesting improved part quality as an additional benefit. Further demonstrating the applicability of the proposed method, a 40-mm-thick laminate was successfully produced with a peak temperature of only 60 °C. This work highlights the potential of room-temperature welding for practical and low-cost production of ultra-thick laminates at room temperature

Thermal reshaping as a route for reuse of end-of-life glass fibre-reinforced acrylic composites

Thermal reshaping has been employed to simulate the end-of-life reuse of liquid-resin-infused thermoplastic acrylic composite laminates, and the associated effects on matrix-dominated mechanical performance and microstructure have been studied. L-shaped laminates were infused at room temperature and subjected to 1 or 4 hot-press flattening cycles (25 min at 120 °C; 11 bar). Compared to the original references, up to 13% higher transverse flexural strengths were measured for the reprocessed laminates. Such a scheme may be readily implemented for high-value reuse without sacrificing fibre length scales, and with minimal cumulative mass loss over successive reheating cycles (10 cycles: 2% and 15 cycles: 2.6%). This study provides important insights to foster a greater understanding of the performance limits of hot-press reprocessing to inform the practical reuse and re-application of sustainable composites in a circular economy

Rationale, design and methodology of APPROACH-IS II: International study of patient-reported outcomes and frailty phenotyping in adults with congenital heart disease.

In recent years, patient-reported outcomes (PROs) have received increasing prominence in cardiovascular research and clinical care. An understanding of the variability and global experience of PROs in adults with congenital heart disease (CHD), however, is still lacking. Moreover, information on epidemiological characteristics and the frailty phenotype of older adults with CHD is minimal. The APPROACH-IS II study was established to address these knowledge gaps. This paper presents the design and methodology of APPROACH-IS II. APPROACH-IS II is a cross-sectional global multicentric study that includes Part 1 (assessing PROs) and Part 2 (investigating the frailty phenotype of older adults). With 53 participating centers, located in 32 countries across six continents, the aim is to enroll 8000 patients with CHD. In Part 1, self-report surveys are used to collect data on PROs (e.g., quality of life, perceived health, depressive symptoms, autonomy support), and explanatory variables (e.g., social support, stigma, illness identity, empowerment). In Part 2, the cognitive functioning and frailty phenotype of older adults are measured using validated assessments. APPROACH-IS II will generate a rich dataset representing the international experience of individuals in adult CHD care. The results of this project will provide a global view of PROs and the frailty phenotype of adults with CHD and will thereby address important knowledge gaps. Undoubtedly, the project will contribute to the overarching aim of improving optimal living and care provision for adults with CHD