Thermoformable high oxygen barrier multilayer EVOH/LDPE film/foam

Technical development and application of supercritical CO2 foaming technology in PCL foam production

Polycaprolactone (PCL) has the advantages of good biocompatibility, appropriate biodegradability, non-toxicity, flexibility, and processability. As a result, PCL-based foams can successfully work in bone tissue engineering, medical patches, drug delivery, reinforcing materials, and other applications. A promising technology for producing PCL foam products is supercritical CO2 (ScCO2) foaming technology, which avoids using organic solvents, is green, and has low foaming agent costs. However, due to the limitations of ScCO2 foaming technology, it is no longer possible to use this technology alone to meet current production requirements. Therefore, ScCO2 foaming technology must combine with other technologies to develop PCL foam products with better performance and matching requirements. This paper systematically reviews the technological development of ScCO2 foaming in producing PCL foams. The molding process of ScCO2 foaming and the conventional preparation process of PCL foam products are discussed comprehensively, including the preparation process, advantages, and disadvantages, challenges faced, etc. Six combined technologies for ScCO2 foaming in the production of PCL foams and the applications of PCL foams are presented. Finally, the future remaining research for producing PCL foams by ScCO2 foaming is analyzed.

Mechanical compressive behavior of pomelo peel and multilayer polymeric film/foam systems

The study of natural cellular materials offers valuable insights into the superior properties and functions underlying their unique structure and benefits the design and fabrication of advanced biomimetic materials. In this study, we present a systematic investigation of the mechanical behavior of fresh and oven-dried pomelo peels. Density measurements revealed the gradient structure of the pomelo peel, which contributed to its mechanical properties. Step-by-step drying revealed two types of water in the peel. Both uniaxial compression and low-strain hysteresis tests were conducted, and the results showed that fresh pomelo peel exhibits soft elastomer-like behavior, while dried pomelo peel behaves more like conventional synthetic polymer foam. Compared to fresh pomelo peel, dried peel samples showed higher compressive modulus and energy loss in 6, 8 and 10% strain hysteresis tests. The rehydration process was studied using hysteresis tests at three different strains. In addition, multilayer gradient EO/EO and LDPE/LDPE film/foams with 16 alternating layers were produced using the microlayer coextrusion technique. The morphology and mechanical properties were examined and indicated great potential for biomimicking the structure and properties of pomelo peel.