A generalizable strategy toward highly tough and heat-resistant stereocomplex-type polylactide/elastomer blends with substantially enhanced melt processability

Deng, Shihao; Ju, Yao; Bai, Hongwei; Xiu, Hao; Zhang, Qin; Fu, Qiang

doi:10.1016/j.polymer.2021.123736

Cited by 28 publications

(23 citation statements)

References 56 publications

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“…The interface between PLA and Hytrel clearly appeared at higher Hytrel contents, showing that the two polymers had poor miscibility. These results are in agreement with those presented by Yan et al [21] with PLA/eSEPS blends and by Deng et al [23] with PLA/EVA blends.…”

Section: Morphologysupporting

confidence: 94%

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Modified Polylactic Acid with Improved Impact Resistance in the Presence of a Thermoplastic Elastomer and the Influence of Fused Filament Fabrication on Its Physical Properties

et al. 2021

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The standard polylactic acid (PLA), as a biodegradable thermoplastic polymer, is commonly used in various industrial sectors, food, and medical fields. Unfortunately, it is characterized by a low elongation at break and low impact energy. In this study, a thermoplastic copolyester elastomer (TPCE) was added at different weight ratios to improve the impact resistance of PLA. DSC analysis revealed that the two polymers were immiscible. A good balance of impact resistance and rigidity was reached using the formulation that was composed of 80% PLA and 20% TPCE, with an elongation at break of 155% compared to 4% for neat PLA. This new formulation was selected to be tested in a fused filament fabrication process. The influence of the nozzle and bed temperatures as printing parameters on the mechanical and thermal properties was explored. Better impact resistance was observed with the increase in the two thermal printing parameters. The crystallinity degree was not influenced by the variation in the nozzle temperature. However, it was increased at higher bed temperatures. Tomographic observations showed an anisotropic distribution of the porosity, where it was mostly present between the adjacent printed filaments and it was reduced with the increase in the nozzle and bed temperatures.

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Section: Morphologysupporting

confidence: 94%

“…Consequently, the impact resistance decreased. Similar observations were found by J. Cai et al, who worked on PLA and poly(ether-blockamide) copolymer [25] and by Deng et al [23], who worked on PLA/EVA. During the impact test, a complete fracture was present in the PLA 4032D samples and PLA/Hytrel-10% blend.…”

Section: Mechanical Propertiessupporting

confidence: 87%

Modified Polylactic Acid with Improved Impact Resistance in the Presence of a Thermoplastic Elastomer and the Influence of Fused Filament Fabrication on Its Physical Properties

et al. 2021

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“…The PLLA/PDLA blends without and with epoxy-functioned modifiers (RMs) were prepared by reactive melt-blending under the catalysis of 0.3 wt% triethylamine at 200 • C, where multi-arm stereo-block PLA copolymers could be in situ generated (as illustrated in Figure 1) along with the stereocomplexation of enantiomeric PLA chains [38,57]. The coupling reaction between epoxy groups of the RMs and hydroxyl end groups of the PLAs was verified by FT-IR.…”

Section: Generation Of Multi-arm Stereo-block Pla Copolymers In Plla/pdla Blendsmentioning

confidence: 99%

“…In this case, the physicochemical properties and sustainable attributes of the SC-PLA could be significantly deteriorated. Very recently, we demonstrated that the introduction of trace amounts (e.g., 0.3-0.5 wt%) of epoxy-functionalized oligo(styrene-acrylic) (ESA) into the blends leads to the in situ generation of comb-like PLA-graft-ESA copolymers containing long PLLA/PDLA branches in the reactive melt-blending process, and these copolymers can behave as highly efficient compatibilizers to stimulate exclusive SC formation [57]. This indicates that reactive blending is a relatively facile and low-cost strategy to remarkably enhance the SC crystallizability of the high-MW enantiomeric blends without sacrificing their valuable properties.…”

Section: Introductionmentioning

confidence: 99%

Substantially Enhanced Stereocomplex Crystallization of Poly(L-lactide)/Poly(D-lactide) Blends by the Formation of Multi-Arm Stereo-Block Copolymers

et al. 2022

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Stereocomplex-type polylactide (SC-PLA) created by alternate packing of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) chains in a crystalline state has emerged as a growingly popular engineering bioplastic that possesses excellent hydrolytic stability and thermomechanical properties. However, it is extremely difficult to acquire high-performance SC-PLA products via melt-processing of high-molecular-weight PLLA/PDLA blends because both SC crystallites and homocrystallites (HCs) are competitively formed in the melt-crystallization. Herein, a facile yet powerful way was employed to boost SC formation by introducing trace amounts of some epoxy-functionalized small-molecule modifiers into the enantiomeric blends during reactive melt-blending. The results show that the SC formation is considerably enhanced with the in situ generation of multi-arm stereo-block PLA copolymers, based on the reaction between epoxy groups of the modifiers and hydroxyl end groups of PLAs. More impressively, it is intriguing to find that the introduction of only 0.5 wt% modifiers can induce exclusive SC formation in the blends upon isothermal and non-isothermal melt-crystallizations. The outstanding SC crystallizability might be attributed to the suppressing effect of such unique copolymers on the separation of the alternately arranged PLLA/PDLA chain segments in molten state as a compatibilizer. Furthermore, the generation of these copolymers does not result in a significant increase in melt viscosity of the blends. These findings suggest new opportunities for the high-throughput processing of SC-PLA materials into useful products.

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“…[12,13] Several compatibilization methods have been frequently utilized to enhance the interfacial adhesion, such as, interfacial coupling via the incorporation of premade block/graft copolymers [14,15] or in situ formation of special copolymers during the blending. [16][17][18] Nevertheless, it is still difficult to achieve highly efficient interfacial compatibilization using these copolymers. On one hand, the low-molecular-weight copolymers have a limited effect on the improvement of interfacial strength due to its inferior Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Manipulating Matrix Crystallization and Impact Toughness of Polylactide/Elastomer Blends via Tailoring Size and Packing Density of Stereocomplex Crystallites Formed at the Interface

Zeng

Luo

Bai

et al. 2022

Macro Materials & Eng

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Constructing stereocomplex (SC) crystallites at the interface of poly(L-lactide) (PLLA)/elastomer blends represent a promising strategy to develop heat-resistant and super-tough PLLA materials because such SC crystallites can behave as not only nucleator to accelerate crystallization of PLLA matrix but also interfacial binder to strengthen interface. The properties of blends could be largely dominated by the SC interfacial layer, however, it is still unclear how the interfacial structure affects nucleating efficiency and interfacial strength. Herein, taking PLLA/poly(ethylene-co-methyl acrylate-graft-poly(D-lactide)) (EMA-g-PDLA) blends as an example, EMA-g-PDLA bearing different chain lengths and grafting densities is prepared to tailor the size and packing density of interface-localized SC crystallites. The results indicate that the interfacial structure and properties of the blends have been successfully manipulated. Compared with low-graft-density long PDLA chains, high-graft-density short ones can readily collaborate with PLLA chains to form numerous SC crystallites with smaller size and higher packing density at the interface and thus dramatically enhance the impact toughness and matrix crystallization rate. Moreover, the toughness is dominated by the content of SC crystallites, but the matrix crystallization is determined by their size and packing density. The work provides a new understanding of SC structure controlling the properties of PLLA/elastomer blends.

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A generalizable strategy toward highly tough and heat-resistant stereocomplex-type polylactide/elastomer blends with substantially enhanced melt processability

Cited by 28 publications

References 56 publications

Modified Polylactic Acid with Improved Impact Resistance in the Presence of a Thermoplastic Elastomer and the Influence of Fused Filament Fabrication on Its Physical Properties

Modified Polylactic Acid with Improved Impact Resistance in the Presence of a Thermoplastic Elastomer and the Influence of Fused Filament Fabrication on Its Physical Properties

Substantially Enhanced Stereocomplex Crystallization of Poly(L-lactide)/Poly(D-lactide) Blends by the Formation of Multi-Arm Stereo-Block Copolymers

Manipulating Matrix Crystallization and Impact Toughness of Polylactide/Elastomer Blends via Tailoring Size and Packing Density of Stereocomplex Crystallites Formed at the Interface

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