Direct ink writing‐based additive manufacturing of styrene‐isoprene‐styrene block copolymer

Adhesives and sealants show fine rheology with good physical and mechanical properties as viscous pastes, a possible starting point for developing direct ink writing (DIW) 3D printing ink. However, many commercial adhesives and sealants take days or weeks to cure fully. DIW 3D‐printed parts made directly from these sealants are not designed for a scalable manufacturing process and high‐volume production. Moreover, most of these adhesives and sealants have volume shrinkage during cure. A systematic understanding of formulation methods and design principles for an elastomeric silicone DIW ink can overcome these issues. This study presents the cogent formulation development of a 3D printable thermoset elastomer silicone that gels and cures isotropically in minutes, reducing cycle time for rapid ink development with no shrinkage during cure. More specifically, we outline the principles of raw material selection of a formulation to achieve excellent rheology, printability, synchronized working, and gel time fitting requirements closer to scalable manufacturing. The reaction kinetics and their corresponding 3D‐printed structural properties are also described. Interest in future work is toward a rational DIW 3D printing ink material development protocol and use of machine learning (ML).Highlights Formulation method flexibility and design principle of DIW ink. Raw material selection principle to achieve optimal rheology for DIW printing. Ink gel kinetics for large‐scale DIW manufacturing. Hydrosilylation conversion over time at different ambient temperatures. Structural properties of DIW 3D printed parts.

Section: Resultsmentioning

confidence: 99%

On the cogent formulation of an elastomeric silicone ink material for direct ink write (DIW) 3D printing

Elahee,

Cheng,

Rong

et al. 2024

Improving 3D printability and interlayer adhesion in ABS/PP immiscible polymer blends

Yesu,

T.,

Goyal

et al. 2024

Self Cite

Printability and interlayer adhesion are the most critical issues in 3D printing of immiscible polymer blends. It can affect structural integrity and mechanical performance of the printed parts. In this work, an effective strategy to improve the printability and interlayer adhesion of immiscible acrylonitrile‐butadiene‐styrene/polypropylene (ABS/PP) blends was implemented by introducing styrene–ethylene/butylene–styrene copolymer grafted with maleic anhydride (SEBS‐g‐MA) as a compatibilizer. The printability of the developed blends was investigated using rheological properties such as absolute value of complex viscosity, loss tangent and die‐swell ratio. Interestingly, it was found that the additive manufactured blends with 20 wt% SEBS‐g‐MA loading showed improved interlaminar shear strength, impact strength, Young's modulus and toughness as compared with the pure blend. Fractography analysis revealed that two different possible failure mechanisms, interface and matrix failure were apparent in the 3D printed samples with and without SEBS‐g‐MA content. This work provides a promising pathway to fabricate the complex structures from polymer blends with improved mechanical properties and surface finish.Highlights This study demonstrated improved interlayer adhesion at the printed interface of immiscible ABS/PP blends in presence of SEBS‐g‐MA. The printability of the developed blends was predicted from rheological properties. Additive manufactured blends with SEBS‐g‐MA loading showed improved mechanical performance.

Statistical modeling and optimization of process parameters for additive manufacturing of styrene–ethylene–butylene–styrene block copolymer parts using solvent cast 3D printing technique

Kumar,

Pandey,

Jha

et al. 2024

Additive manufacturing of thermoplastic elastomers is challenging using fused deposition modeling due to their high melt viscosity, low column strength, and poor fusion among layers. Solvent‐cast 3D printing (SC‐3DP) is an efficient alternative to successfully 3D print such materials. However, selection of suitable 3D printing parameters is crucial to realize parts with optimum physicomechanical properties. In this work, statistical modeling and SC‐3DP parameter optimization for styrene–ethylene–butylene–styrene (SEBS) block copolymer were performed. The effect of 3D printing process parameters on shrinkage, relative density, and tensile strength was analyzed using response surface methodology. Experiments were planned as per central composite design and analysis of variance was performed to evaluate the significant parameters. SEBS content in the polymer solution significantly affected the shrinkage of SC‐3DP samples. Moreover, relative density and tensile strength were significantly affected by print speed and layer height. A significant interaction between print speed and layer height was also noticed for tensile strength and relative density of printed samples. Multi‐objective optimization using genetic algorithm was also performed to minimize shrinkage and maximize relative density and tensile strength. Finally, a case study was conducted comparing the physicomechanical properties of SC‐3DP samples printed at optimized process parameters and compression molded samples.Highlights Statistical models were developed using response surface methodology. Genetic algorithm based multi‐objective optimization was performed. Optimum solvent‐cast 3D printing (SC‐3DP) process parameters were determined.