Lightweight, low-shrinkage and high elastic poly(butylene adipate-co-terephthalate) foams achieved by microcellular foaming using N2 & CO2 as co-blowing agents

Shrink-Resistant Poly(butylene adipate-co-terephthalate) Foam Reinforced with Crystalline Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Particles

“…However, the substantial post-foaming shrinkage ratio of pure PBAT foam can reach up to 80%, which poses a serious challenge to its practical applications. 12,13 The post-foaming shrinkage observed in PBAT foam is similar to other polymers with their glass transition temperatures below ambient temperature, such as thermoplastic polyurethane, thermoplastic polyester elastomer (TPEE), and low-density polyethylene. 14−18 This phenomenon can be attributed to several factors, including inadequate stiffness of the cell walls, rapid diffusion of blowing agents out of the foam, low open-cell content, and rapid relaxation of chain segments.…”

“…The widespread application of polymer foam in a broad range of industries, such as packaging, construction, aerospace, and biomedicine, has propelled research endeavors toward the development of biodegradable alternatives, which stems from the urgent need to mitigate environmental pollution that threatens global sustainability. − Currently, various biodegradable polymers are commercially available, including polylactic acid (PLA), polybutylene succinate (PBS), poly­(butylene adipate- co -terephthalate) (PBAT), poly­(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV), polycaprolactone, and poly­(butylene succinate-butylene terephthalate) (PBST). − PBAT has gained significant attention due to its impressive toughness, cost effectiveness, and remarkable foamability, with an initial expansion ratio (ER) of up to 30 when utilizing supercritical CO 2 (scCO 2 ) as a blowing agent. However, the substantial post-foaming shrinkage ratio of pure PBAT foam can reach up to 80%, which poses a serious challenge to its practical applications. , The post-foaming shrinkage observed in PBAT foam is similar to other polymers with their glass transition temperatures below ambient temperature, such as thermoplastic polyurethane, thermoplastic polyester elastomer (TPEE), and low-density polyethylene. − This phenomenon can be attributed to several factors, including inadequate stiffness of the cell walls, rapid diffusion of blowing agents out of the foam, low open-cell content, and rapid relaxation of chain segments. ,, …”

Calculating diffusion coefficients from molecular dynamics simulations for modelling foam processes of polypropylene: Investigating different process conditions and blowing agents

“…40 In two other recent works the diffusion coefficient for CO 2 in poly(butylene adipate-co-terephthalate) and polystyrene were measured and a pressure dependence was found. 41,42 This discrepancy can be explained by the method of measurement. The diffusion coefficient was measured by applying an external blowing agent pressure on the melt, while in our simulation the pressure was applied on the system of the polymer loaded with the CO 2 .…”

Super‐Elastic and Dimensionally Stable Polyether Block Amide Foams Fabricated by Microcellular Foaming with CO2&N2 as Co‐Blowing Agents

“…An improved microcellular foaming with N 2 and CO 2 as coblowing agents was developed to address the shrinkage problem in our previous works. [9,4,21] The results show that introducing N 2 and CO 2 as co-blowing agents can not only stabilize the cellular structure, but also restrict the shrinkage of the cell walls. The PBAT foams achieved a high expansion ratio of 14.9 fold and a restricted shrinkage of less than 6%.…”

“…Compared to traditional chemical foaming, microcellular foaming can not only obtain a structure-tunable cellular morphology, but also endow foams with unique multifunctional properties, such as higher toughness and impact strength, better thermal insulation, outstanding light reflection, and dielectric properties. [9] Driven by these favorable structures and functions, a series of microcellular PEBA foams has been developed and applied in related fields. Xu [4] et al obtained a PEBA microcellular foam with a high expansion ratio of 24 and a high cell density using supercritical CO 2 as the blowing agent, which exhibited a high tensile strength and a good resilience rate of 80%.…”