Toughness Of Polylactic Acid Research Articles

Phosphorus-nitrogen-containing flame-retardant plasticizers derived from L-lactic acid for poly (lactic acid) improved toughness, flame retardancy and crystallization

Designing highly-effective and environmentally friendly biobased flame-retardant plasticizers for polylactic acid (PLA) remains a formidable challenge. In this study, we synthesized four novel phosphorus-nitrogen-containing L-lactic acid-based flame-retardant plasticizers with adjustable chemical structures and phosphorus content, designated as NPDL-Cn, where ’n’ corresponds to the alkyl groups numbers in the alkylamine chain (with n = 4, 6, 8, and 10). Incorporating NPDL-Cn into the PLA matrix offered a twofold benefit, significantly enhancing both the flame retardancy and toughness of PLA. Remarkably, as incorporating 20 phr NPDL-Cn, the resulting blends all achieved UL-94 V-0 grade, and their limiting oxygen index reached about 30.8 %, 29.5 %, 28.3 % and 27.2 %, respectively. A comprehensive analysis of the volatile gases and char layer generated during combustion showed that the flame-retardant mechanism of NPDL-Cn in PLA significantly influenced both the condensed-phase and gas-phase behavior. Meanwhile, NPDL-Cn effectively overcame the brittleness and rigidity of PLA, thus realizing the enhancement of its toughness. In particular, as compared to a mere 3.7 % and 1.7 MJ/m3 for neat PLA, when the methylene numbers of NPDL-Cn were 4, the elongation at break and tensile toughness of the PLA/NPDL-C4 exhibited a substantial increase to 180.1 % and 43.4 MJ/m3, respectively, due to the best interfacial tension of NPDL-C4 with PLA matrix. Additionally, while the tensile strength of neat PLA is notably high at 50.7 MPa, the introduction of PLA/NPDL-C4 results in a significant decrease to 26.3 MPa. Interestingly, biodegradation experiments showed that NPDL-C4 was decomposed into non-toxic and harmless small molecules. This study presents a method for constructing toughened and flame-retardant PLA blends by modulating the alkyl chain length of flame-retardant plasticizers and elucidating their structure–property relationships.

Interfacial compatibilization of fully biodegradable polylactic acid/polybutylene adipate terephthalate blends for improved mechanical and physical performance

Environmental problems, such as plastic pollution and global warming, are motivating researchers worldwide to seek sustainable biodegradable polymers that would replace the nonbiodegradable ones. Polylactic acid (PLA) has emerged as one of the most promising alternatives due to its superior mechanical and thermal qualities compared to other types of biopolymers. However, PLA has some inherent deficiencies such as its brittleness and rigidity, which limit its further use. This study investigates the toughening effect of different amounts of polybutylene adipate terephthalate (PBAT) on PLA, and the compatibilization effect of ADR, a chain extender, on the PLA/PBAT blends. The results indicate that PBAT can significantly enhance the flexibility and toughness of PLA. PLA and PBAT can react with ADR to form PLA-g-PBAT copolymers thereby increasing the compatibility of these two polymers. The tensile strength, elongation at break and impact strength of the PLA/PBAT/ADR blends are all increased due to the increased compatibility. The chain extension reaction can promote the formation of a better crystalline structure in the PLA/PBAT blends, which leads to the increase of the Tm of PLA. Besides, the hydrophilicity of PLA can be adjusted by blending with PBAT, and the hydrophilicity of the blends with blend ratios of 75:25, 50:50 and 25:75 can also be enhanced after the addition of ADR.

Effect of UV-induced crosslink network structure on the properties of polylactic acid/polybutylene adipate terephthalate blend

Over the past few decades, biobased polylactic acid (PLA) has emerged as the most promising option to replace some of the fossil-based and nonbiodegradable polymers due to environmental concerns. In this study, a flexible polymer, polybutylene adipate terephthalate (PBAT) was blended with PLA to improve the toughness and flexibility of PLA, and the PLA/PBAT blend was further UV-induced to form crosslink structure. The results show that the flexibility and toughness of PLA could be significantly enhanced when PBAT was introduced, and the compatibility of PLA and PBAT could be enhanced by the development of a crosslink structure. Especially, the elongation at break and unnotched impact strength of ABT-UV30 (PLA/PBAT/triallyisocyanurate (TAIC) exposed to ultraviolet (UV) light for 30 min) was increased to 3.9 and 8.4 times of neat PLA. The glass transition temperature (Tg) of PLA was increased from 63.4 to 72.9 °C as the radiation duration was prolonged to 60 min. The melting point temperature of PBAT was also increased gradually until it eventually coincided with that of PLA. The thermalgravimetric analyzer thermograms show that a moderate amount of UV radiation can improve the thermal stability of the sample while an excessive amount of UV radiation can reduce the degradation temperature.

Simultaneous improvement of tensile strength and toughness of polylactic acid by incorporating a biodegradable core‐shell nanofiller with double polymer layers

AbstractWhile blending with flexible polymers has been a commonly employed strategy to enhance the toughness of polylactic acid (PLA), it's still a great challenge to avoid the sacrifice of tensile strength at the same time. In this work, we demonstrate a promising route to simultaneously improve the strength and toughness of PLA by compounding PLA with poly(ε‐caprolactone) (PCL) and PLA grafted multi‐walled carbon nanotubes core‐shell nanofiller (MWNT‐PCLPLA) via a two‐step ring‐opening polymerization and have analyzed the strengthening and toughening mechanism through molecular dynamics simulation. The double polymer layers of MWNT‐PCLPLA effectively improve the interfacial interaction between MWNTs and the matrix, in which the outer PLA layer has the same molecular structure with the matrix and facilitates stress transfer, while the flexible PCL layer can absorb energy through self‐deformation and induce local plastic deformation of the matrix. When the content of MWNTs was only 1 wt%, the strength and elongation at break of PLA/MWNT‐PCLPLA nanocomposites were increased by 47.92% and 690.11% compared to neat PLA. Furthermore, the toughness of nanocomposites reached 11.93 MJ/m3, which is about 16 times that of neat PLA. This novel core‐shell nanofiller with double polymer layers is expected to be further applied in other polymer systems.Highlights A core‐shell nanofiller with double polymer layers was synthesized. Improved dispersion and interfacial compatibility of nanofillers in matrix. The crystallization ability of PLA was improved by functionalized MWNTs. Simultaneously improved strength and toughness of PLA/MWNT‐PCLPLA nanocomposite.

Enhancing the strength and toughness of polylactic acid through fused deposition modeling‐induced orientation and nucleation effects of attapulgite

AbstractSimultaneously enhancing strength and toughness through simple and low‐cost methods has always been a challenge for polylactic acid (PLA) materials. In this context, natural attapulgite (ATT) nanorods were used as fillers combined with fused deposition modeling (FDM) to improve the strength and toughness of PLA. The printable PLA nanocomposite filaments filled with ATT nanorods were prepared by melting compounding and smoothly printed via a commercial FDM three‐dimensional (3D) printer. The influences of FDM process and ATT filling on the properties of PLA/ATT composite parts were evaluated through microstructure analysis, rheological, and mechanical tests. The results suggest that PLA/ATT composite parts manufactured by FDM exhibit superior mechanical properties, which can be attributed to the FDM induced orientation and nucleation effect of ATT nanorods. The tensile strength can reach 56 MPa with the addition of 2 wt% ATT at a nozzle temperature of 205°C, increasing by 24% compared to pure PLA. In addition, the fracture elongation of PLA/ATT parts printed by FDM has significantly increased to 26%, which is 924% higher than pure PLA. Furthermore, the filling of ATT significantly improves the storage modulus of composite parts. This work provides a new high‐strength, ultra tough, low‐cost, and printing stable PLA/ATT composite material and forming method, offering a promising avenue for the wider application of PLA and ATT in the future.

Construction of high-performance and sustainable polylactic acid composites for 3D printing applications with plasticizer

Polylactic acid (PLA) attains much attention because of its biodegradability, biocompatibility, and high strength, but its further application was remarkably hindered by its brittleness. In order to improve the toughness of PLA, a biodegradable composite was prepared by blending ductile polycaprolactone (PCL), stiff microcrystalline cellulose (MCC), and green plasticizer tributyl citrate (TBC) with PLA by melting extrusion. The physicochemical properties and microstructure of PLA composites were thoroughly investigated using FTIR, TGA, DSC, XRD, melting rheology, optical transmittance, 3d printing, tensile tests, and SEM. The tensile tests results show that introduction of TBC exhibited a remarkable improvement effect in the elongation at break of PLA/PCL/MCC (PPM) composite, increasing from 2.9 % of PPM to up to 30 % of PPM/6TBC and PPM/8TBC. Noticeably, the strength of PPM/TBC composites (at least 33.1 MPa) was enhanced compared with that of PPM (28.2 MPa). The plasticization of TBC, enhancing the compatibility of composites, and reinforcing effect of MCC were identified as pivotal factors in toughening and reinforcing PLA. Furthermore, it is observed that the incorporation of TBC contributed to enhanced thermal stability, crystallinity, and rheology property of composites. This research supplies a novel approach to bolstering the toughness of PLA and broaden its potential applications.

A Mechanical Model for Stress Relaxation of Polylactic Acid/Thermoplastic Polyurethane Blends

Polylactic acid (PLA) is considered a promising biodegradable polymer alternative. Due to its high brittleness, composite materials made by melt blending thermoplastic polyurethane (TPU) with PLA can enhance the toughness of PLA. To understand the forced aging caused by stress relaxation in polymer materials, this study explains the stress relaxation experiments of PLA/TPU blends with different mass ratios under applied strain through mechanical model simulations. The Kelvin representation of the standard linear solid model (SLSM) is used to analyze the stress relaxation data of TPU/PLA blends, successfully explaining that the Young’s moduli (E1 and E2) of springs decrease with increasing temperature and TPU content. The viscosity coefficient of the PLA/TPU blends decreases with increasing temperature, and its reciprocal follows the Arrhenius law. For TPU/PLA blends with increased concentration of TPU, the activation energy for stress relaxation shows a linear decrease, confirmed by the glass transition point measured by DMA, indicating that it does not involve chemical reactions.

Super-tough polylactic acid blends via tunable dynamic vulcanization of biobased polyurethanes

Polylactic acid (PLA) is a biobased plastic with biodegradability, biocompatibility, and high-strength properties; however, its inherent brittleness limits its widespread application. Toughness can be improved by physical blending, chemical copolymerization, and reactive blending of PLA with flexible components. As highly engineered block polymers, polyurethanes (PUs) can improve the toughness of PLA through physical blending or in situ polymerization. However, current research on PU-toughened PLA is hindered by poor compatibility, toughening, and dependence on petrochemical resources. Therefore, to address these issues, we developed a novel biobased millable polyurethane (PO3G-MPU) containing unsaturated double bonds and used it to toughen PLA via peroxide-initiated dynamic vulcanization. The results showed that balancing toughness and strength is possible, with the notched impact strength and tensile strength of the prepared PLA/MPU blends reaching 59.01 kJ/m2 and 43.97 MPa, respectively. The massive shear yielding and plastic deformation of the PLA matrix induced by the crosslinked PO3G-MPU were responsible for the main toughening mechanism. These results provide a new perspective on research on PU-toughened PLA.

In-situ self-crosslinking strategy for super-tough polylactic acid/ bio-based polyurethane blends

As a bio-based degradable plastic, polylactic acid (PLA) is highly commercialized, but its inherent brittleness limits its widespread use. In-situ polymerization techniques are effective in improving the toughness of PLA. However, the enhancement of the toughening effect in polyurethanes (PUs) through in-situ self-crosslinking still requires improvement and heavily relies on petroleum-derived feedstocks in certain approaches. In this paper, 1,3-polypropanediol (PO3G) of bio-based origin rather than conventional polyols like polyethylene glycol (PEG) and poly propylene glycol (PPG) was used. PLA/PO3G-PU blends were prepared via an in-situ self-crosslinking strategy. With a notch impact and tensile strength of 55.95 kJ/m2 and 47.77 MPa (a retention rate of 68.9 % compared with pure PLA), respectively, PLA/PO3G-PU blends achieved a better balance between stiffness and toughness. This work provides a new option for PLA to achieve a stiffness-toughness balance and get rid of dependence on petrochemical resources.

Mirror assembly of spherical chitosan-based additives: Towards a circular revolution of PLA from high-value applications to soil degradation

Polylactic acid (PLA) is recognized as a promising alternative to traditional petroleum-based plastics due to its excellent biodegradability and well-balanced mechanical properties. Nevertheless, the disadvantages of PLA such as flammability in fire, susceptibility to UV light attack, and slow natural degradation rate limit its application and recovery in high-security areas. In this work, a spherical chitosan-based additive DMPC-Al with mirror-symmetric internal structure was assembled by layer-by-layer electrostatic reactions, resulting in PLA characterized excellent comprehensive performances. When 7 wt% DMPC-Al was added into PLA, the LOI value of the composite PLA/7DMPC-Al was increased to 29.6%, and UL-94 reached V-0 grade without any molten droplets. The peak heat release rate and total heat release rate were reduced by 13.5% and 16.2%, respectively, and the carbon layer was highly self-expanding. In addition, the UPF of PLA/7DMPC-Al was increased to 34.45 from 0.45 of pure PLA, blocking most of the UV light attacks and extending the service life of PLA. Surprisingly, DMPC-Al actually improved the impact toughness of PLA by 38.5% and facilitated PLA to work continuously when drawing large curved shapes by 3D printing. More importantly, the introduction of DMPC-Al changed the sensitivity of PLA to water and provided sufficient energy for microbial growth, thus accelerating the degradation rate of PLA in the soil under abandoned buildings. This work provides a practical and feasible strategy to achieve multifunctionality of degradable plastics.

Green synthesis of bio-based flame retardant/natural rubber inorganic-organic hybrid and its flame retarding and toughening effect for polylactic acid

Polylactic acid (PLA) has garnered significant interest as a bio-based polymer due to its favorable thermal and processing characteristics, as well as its notable economic and environmental benefits. However, the drawbacks such as flammability and poor toughness of PLA severely constrained its applications in more fields. Here, based on the outstanding flame-retardant properties of core-shell flame retardant (CSFR) and the toughening potential of natural rubber (NR), we synthesized inorganic-organic hybrid of CSFR-NR using an aqueous synthesis to synchronous optimization of the comprehensive performance of PLA. The as-prepared CSFR-NR with “hard core and soft shell” possess the ability to promote char formation and facilitate uniform dispersion in the PLA matrix. Consequently, the PLA/CSFR-NR showed an excellent flame retardancy with the limiting oxygen index (LOI) value of 31.5 % and UL-94 V-0 rating and synergistic toughening effect with absolutely improvement in elongation at break and notched izod impact strength, achieving a balance between the fire safety and mechanical performance. Moreover, the degradation rate of PLA has also been substantially promoted by CSFR-NR in simulated seawater. Hence, this study offers a straightforward, efficient, and environmentally friendly strategy for creating high-performance flame retardant and toughened bioplastics.

Effect of curcumin-modified nanodiamonds on properties of eco-friendly polylactic acid composite films

Polylactic acid (PLA) has attracted much attention as a biodegradable polymer material, but its inherent brittleness limits its application. In order to improve the overall performance of PLA, thermoplastic polyurethane (TPU) was first blended with PLA to improve the toughness, and then curcumin-functionalized nanodiamond (ND-Cur) was added to the polymer matrix to improve the strength and toughness of PLA. The effects of nanoparticles on the structure, thermal and mechanical properties of polymer matrix were investigated by scanning electron microscopy, thermogravimetric analysis and tensile testing. When the addition of ND-Cur is 1.5 wt%, the mechanical properties of the composite are the best, and the elongation at break is 124.8%, which is 119.9% higher than that of PLA. At this time, the improvement of thermal stability is also the most significant, and the T5% (temperature at 5% heat loss of sample) of the film is 47.9% higher than that of pure PLA. In addition, the modification also improved the hydrophobicity of the composite film.

Recent Advances of Polylactic Acid (PLA) Toughening Methods

Nowadays, polylactic acid (PLA) has been one of the most important packaging materials in daily life. PLA is eco-friendly because it can be made from renewable resources and is degradable, but it also has a drawback that is lack of toughening. In this review, papers about 3 main methods that could help improve the toughening of the PLA have been collected. They are blending, copolymerization and composition. Blending is a physical method to make the materials uniformly to improve the properties of the material. Copolymerization is the reaction of polymerizing various compounds into one substance under certain conditions. Composition is the termination of reaction by combining two growing free radicals to form a saturated macromolecule. This work will give some exact examples to improve the toughening of the PLA. It is expected that there will be better research methods and materials that are able to improve the toughness of PLA in the future.

Enhanced strength and toughness of polylactic acid by blending with modified natural rubber having acetate pendant group

Among biobased and biodegradable polymers, polylactic acid (PLA) is most widely used one. However, its poor mechanical properties need to be enhanced. In this study, PLA blend film with improved mechanical properties were developed without compromising any bio-content. For this, natural rubber derivative with acetate pendant group (ANR) and PLA blend films were prepared. First, natural rubber was epoxidized, and then partial acetylation was achieved by the ring-opening reaction of the epoxy groups. The epoxidation and the acetylation were examined by FTIR analysis. 1H-NMR spectrum revealed a 29% epoxidation and 8.25% acetylation degree. The Tg of natural rubber (−66°C) increased to −41°C and −31°C after epoxidation and acetylation, respectively. The compatibility of ENR and ANR with PLA was evident from the DSC results and Molau test. The morphology of PLA blend film containing 25 wt% of ANR (ANR25) was observed as well-dispersed fine droplets by SEM images. The tensile strength, elastic modulus, and yield strength of ANR25 were measured as 11.6 MPa, 397.3 MPa, and 6.9 MPa, respectively. These values are considerably higher than neat PLA film. Compared to reported studies on PLA toughening so far, increments in both the strength and elongation of ANR25 were observed by tensile tests. Moreover, highest toughness among all samples was determined as 18.8 MJm−3 for ANR25, which is 1.8 times higher than neat PLA. Thus, a strong and tough bio-based PLA blend was developed for film application such as packaging and sheeting.

Preparation and Mechanism of Toughened and Flame-Retardant Bio-Based Polylactic Acid Composites

As a biodegradable thermoplastic, polylactic acid (PLA) shows great potential to replace petroleum-based plastics. Nevertheless, the flammability and brittleness of PLA seriously limits its use in emerging applications. This work is focused on simultaneously improving the flame-retardancy and toughness of PLA at a low additive load via a simple strategy. The PLA/MKF/NTPA biocomposites were prepared by incorporating alkali-treated, lightweight, renewable kapok fiber (MKF) and high-efficiency, phosphorus-nitrogenous flame retardant (NTPA) into the PLA matrix based on the extrusion-injection molding method. When the additive loads of MKF and NTPA were 0.5 and 3.0 wt%, respectively, the PLA/MKF/NTPA biocomposites (PLA3.0) achieved a rating of UL-94 V-0 with an LOI value of 28.3%, and its impact strength (4.43 kJ·m-2) was improved by 18.8% compared to that of pure PLA. Moreover, the cone calorimetry results confirmed a 9.7% reduction in the average effective heat of combustion (av-EHC) and a 0.5-fold increase in the flame retardancy index (FRI) compared to the neat PLA. NTPA not only exerted a gas-phase flame-retardant role, but also a condensed-phase barrier effect during the combustion process of the PLA/MKF/NTPA biocomposites. Moreover, MKF acted as an energy absorber to enhance the toughness of the PLA/MKF/NTPA biocomposites. This work provides a simple way to prepare PLA biocomposites with excellent flame-retardancy and toughness at a low additive load, which is of great importance for expanding the application range of PLA biocomposites.

Toughening Modification of Polylactic Acid by Long-Chain Hyperbranched Polymers Containing Polycaprolactone end Groups

The hyperbranched polyester (HBPEs) were synthesized by the "one-step method" and grafted with caprolactone (ε-Cl) to obtain long-chain hyperbranched polymers (LCHBPs-Cl). In this study, LCHBPs-Cl with Cl long chain end groups were used for the first time to toughen and strengthen polylactic acid (PLA) by melt blending. Compared with pure PLA, the most significant toughening effect was obviously when the addition amount of LCHBPs-Cl was 2.0 phr. The tensile strength increased from 37.00 to 62.61 MPa. The impact strength was increased from 14.88 to 18.50 kJ. The elongation at break increased from 1.80% to 2.50%. The scanning electron microscope (SEM) images showed the impact section of the blends became rough, the brittle-ductile fracture transition occurred, and a large number of white wire drawing phenomena were produced. Due to the formation of topological entanglement and cohesive entanglement between the long-chain substituents of LCHBPs-Cl and PLA molecular chains, the plastic deformation of PLA was successfully improved, and the toughness of polylactic acid was highly improved.

Influence of Styrene-Ethylene-Butylene-Styrene and Stearic Acid on Poly(Lactic) Acid/Alumina Filament Composite for Fused Deposition Modeling Application

This study investigated the influence of adding styrene-ethylene-butylene-styrene (SEBS) and stearic acid (SA) on poly (lactic) acid (PLA) with nano-alumina (Al2O3) filament composite for fused deposition modeling (FDM) 3D printing (3DP) application. The filament composites were produced via hot-melt extrusion using a twin-screw extruder. Materials characterization and mechanical testing were conducted to determine the effect of SEBS+SA. Fourier transform infrared spectroscopy (FTIR) illustrated the interaction of the aliphatic group of PLA and SEBS+SA. XRD data showed that the SEBS+SA has no significant effect on crystallinity, but the differential scanning calorimetry (DSC) data showed a decreasing trend. Due to the nature of SEBS+SA, the heat capacity increased to 1.222 J/g•C°. The cold crystallization, melting, and degradation temperatures were reduced by 18.34°C, 5.29°C, and 25.19°C, respectively. An increase in the developed filament composite’s processability was evident in the MFR data. The axial strain and the toughness of PLA with nanoAl2O3 were increased significantly by 402.54% and 48.20%, respectively. Furthermore, the SEM images revealed overlapping of intra-and interlayers of the 3D printed specimens.

Bio-Based Poly(lactic acid)/Poly(butylene sebacate) Blends with Improved Toughness.

A series of poly(butylene sebacate) (PBSe) aliphatic polyesters were successfully synthesized by the melt polycondensation of sebacic acid (Se) and 1,4-butanediol (BDO), two monomers manufactured on an industrial scale from biomass. The number average molecular weight (Mn) in the range from 6116 to 10,779 g/mol and the glass transition temperature (Tg) of the PBSe polyesters were tuned by adjusting the feed ratio between the two monomers. Polylactic acid (PLA)/PBSe blends with PBSe concentrations between 2.5 to 20 wt% were obtained by melt compounding. For the first time, PBSe’s effect on the flexibility and toughness of PLA was studied. As shown by the torque and melt flow index (MFI) values, the addition of PBSe endowed PLA with both enhanced melt processability and flexibility. The tensile tests and thermogravimetric analysis showed that PLA/PBSe blends containing 20 wt% PBSe obtained using a BDO molar excess of 50% reached an increase in elongation at break from 2.9 to 108%, with a negligible decrease in Young’s modulus from 2186 MPa to 1843 MPa, and a slight decrease in thermal performances. These results demonstrated the plasticizing efficiency of the synthesized bio-derived polyesters in overcoming PLA’s brittleness. Moreover, the tunable properties of the resulting PBSe can be of great industrial interest in the context of circular bioeconomy.

Highly crystallized and tough polylactic acid through addition of surface modified cellulose nanocrystals

AbstractTo prepare a fully organic polylactic acid (PLA)‐based bio‐nanocomposite, cellulose nanocrystals (CNCs) were grafted by PLA through ring‐opening polymerization (ROP) of L‐lactide monomers onto CNCs. The grafting process was evaluated by 1HNMR and FTIR spectroscopic methods. The effect of surface‐modified CNCs (M‐CNCs) was investigated on thermal, mechanical, rheological, and dynamic mechanical thermal properties of PLA. The M‐CNCs were successfully dispersed in the PLA matrix. Isothermal and non‐isothermal DSC studies revealed that M‐CNCs caused an intensive increase in crystallization kinetics and therefore nucleation density and crystallization extent. DSC, XRD, and DMTA analyses indicated the formation of different crystal structures [α, α', β] in PLA after addition of M‐CNCs. Rheological analysis was carried out for microstructural investigation of the nanocomposites. Interestingly, after the addition of M‐CNCs not only the tensile strength and modulus of the samples increased but also the toughness of PLA was considerably improved.

The coupling effect of cellulose nanocrystal and strong shear field achieved the strength and toughness balance of Polylactide

Up to now, unbalanced mechanical properties and poor heat resistance have become two major problems of polylactic acid (PLA). In this study, the coupling between Cellulose nanocrystal (CNC) and strong shearing field formed a unique hierarchical structure. Compared with pure PLA, the tensile strength of DPIM PLA/CNC increased from 57.9 MPa to 79.6 MPa without sacrificing the toughness of PLA, and the vicat softening temperature of DPIM PLA/CNC increased from 60 °C to 155 °C. The microstructure of PLA/CNC composites was analyzed by SEM, SAXS and WAXD, and it was found that the coupling effect of CNC and strong shear flow field could significantly change the crystallization behavior of PLA. CNC could increase PLA shish length from 251 nm to 889 nm under the action of shear field. At the same time, due to this coupling effect, more PLA shish-kebab structures were induced at the interface. This special hierarchical structure composed of CNC and PLA Shish-Kebab is of great significance and can provide important guidance for achieving the balance of strength and toughness of polymer materials.