Prepared using high performance stretch Volume Bionic structural material flow field regulation microstructure

Polylactic acid (PLA) as the most promising one of biodegradable polymers, because of poor toughness, ductility, and thermal deformation capacity has been greatly limited in large-scale applications. Preparation also has high toughness, good ductility, high strength, high modulus and excellent resistance to thermal deformation capacity of PLA remains a huge challenge. However, the biological nature with limited resources through sophisticated structure of the building, to build a complicated multi-layered structure, thereby having excellent strength and toughness. However, the native structure and completely reproduce the material by artificial synthesis and processing of multi-level regulation of the microstructure of the material microstructure is difficult. South China University of Technology Academy team EXTRUDER developed a new processing equipment – Volume extensional rheology eccentric rotor extruder (Eccentric Rotor Extruder, ERE) [ 123], which is equipped with a strong stretching continuous volume flow field, the flow field using ERE regulatable tensile material microstructure alignment structure (Composites Science and Technology, 2019, 169, 135-141). Inspired by the multi-level structure of compact bone orientation using the orientation microstructure tensile ERE volume flow field structures may be regulated material EXTRUDER Academy team on an industrial scale of the PLA Bionic structural material Preparation and \”ACS Applied Materials & Interfaces\” entitled \”ConstructingBone-Mimicking High-Performance Structured Poly (lactic acid) by an Elongational Flow Field and Facile Annealing Process\” of research papers on journals . The PLA imitation bone structure materials with unique multi-level structure, to obtain a similar compact bone collagen by volume in the flow field generated in-situ tensile nanofibers TPU (Thermoplastic Poly (ether) urethane Nanofibers, TNFs)Fibers (Collagenfibers), PLA nanosheet crystals (lamellae) regularly arranged along TNFs oriented constructs similar to compact bone hydroxyapatite nanocrystals (HA), TNFs formed with good quality and dense interfacial layer of PLA lamellae Collagen fibers bone interface similar to HA. The PLA imitation bone structural materials interlocked three-dimensional network of interconnected lamellae (Interlocked 3D Network Lamellae) extended-chain and platelets (Extended-chain Lamellae) reinforcing the strength and modulus of the structural material; so that the PLA Bionic while super tough material having a structure also has a high modulus, an excellent balance between strength and thermal deformation resistance.

Preparation process of FIG. 1. PLA imitation bone structure and microstructure schematic structural material, three-dimensional representation (a) ERE\’s, (b) a polylactic acid / TPU nanofiber composite, (c) PLA imitation annealing the bone structure of the material; a-1-c1) are schematic respective composite microstructureusing a tensile ERE volume flow field is formed in situ and have made the alignment TNFs and extended molecular chains PLA PLA composite, PLA PLA Bionic composite material structural materials under appropriate annealing conditions, as shown in Figures 1 and 2.

Figure 2. The microstructure PLA Bionic structural material, (a, d) PLA lamellae tightly (compacted lamellae) wrapped in TNF surface and form a larger hybrid-fiber, in hybrid- growth is formed around fiber loose platelets (regular lamellae); (b, e) PLA lamellae interspersed with each other adjacent growing a three dimensional structure; SEM overall configuration of (c) PLA Bionic structural material; (f, i) cortical bone the overall three-dimensional structure and a schematic view of SEM; (g, h, j) is formed in a single PLA lamellae package TNFs unique microstructure; lamellar thickness dimension statistical distribution histogram (k) Regular lamellae of; (l) PLA lamEllae interlocking three-dimensional structure of interconnected schematic; schematic (m) of different molecular chain orientation PLA platelets theSuch structural material Bionic PLA, PLA molecular chains having a thickness of 170-270 nm tight sheet TNFs tightly wrapped in the surface of the crystal, and the crystal growth surface sheet formed close sloppy, just outside the tough (FIG. 3) platelets \”protection sleeve\” TNFs protected from damage, and adjacent surrounding sheet TNFs crystal outgrowth gap tends to easily platelets each other grow to form an interlocking network of the 3D structure when met, FIG. 2d, e, as shown in L; since ERE strong tensile deformation volume effect and the in situ formed TNFs synergistic effect, PLA length and width are formed along the surface TNFs thickness in the axial direction is 1.13 μm, respectively, 0.98 μm and 30 nm platelets extended-chain, extended-chain crystals formed sheet similar to \”bead\” of the adjacent platelets concatenated together to form the structure (FIG. 2g, as shown j) interlocked.

FIG 3. PLA Bionic structural material of TNF thickness characterized interfacial layer PLA matrix and, (a, b) AFM modulus distribution, (c, d) is a figure AB and CD modulus change graph of

Fig 4. (a) stress – strain curve, (b) mechanical performance statistics data, (c) and this paper Structured PLA Document PLA composite comparative notch impact strength and Young\’s modulus, (d) thermal stability test (1: Structured PLA, 2: Neat PLA, 3: PLA composite)just outside these tough \”protective sleeve\”, and the 3D structure of interconnected interlocking \”rib\” are beneficial to improve the mechanical properties of PLA material imitation bone structure, and mechanical properties of pure PLA (Young\’s modulus of 1.73 GPa, the elongation at break 5.8 %, the notched impact strength of 2.5 (∥) and 2.8 (⊥) KJ / m

2 ^{) as compared to Young\’s modulus 2.15 GPa PLA capacity Bionic structural material, breaking elongation of 48.5%, notched impact strength was 69.0 KJ / m} 2 ^{(∥) and 90.3KJ / m} 2 ^{(⊥), 24.3% were improved, 8.4,27.6 and 32.3 times, the tensile strength decreased only 9.7%; while it breaks the polymer composite material significantly toughened unavoidable a significant reduction in material strength and modulus of the conventional wisdom, and PLA Bionic structural material while also having good thermal deformation resistance. Such rapid industrial grade of PLA Bionic structural material having excellent properties can be enormous potential applications in the field of construction and bio-engineered material, such as artificial bones and tissue scaffolds. The first author of this paper is} Dr. School of Mechanical and Automotive Engineering, South China University of Technology He Yue, Qu Jinping Academy of Sciences is corresponding author of the paper.