Role of Stereoregularity of Polylactide on the Microstructure and Mechanical Properties of Reactive Polylactide/Poly(ε‐Caprolactone)/Triisocyanate Bio‐Polyester Blends

The quote only partly states this claim.

The tensile strength of 6100D/PCL/tri-HDI blend was 47.2 MPa.

“The tensile strength of 6100D/PCL/tri-HDI blends was as low as 47.2 MPa.”

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The elongation at break of PLA/PCL/tri-HDI blends for 6100D, 2003D, and 4060D were 151.4%, 126.3%, and 168.1%, respectively, compared with 7.2%, 3.9%, and 27.6% for the corresponding PLA/PCL blends without tri-HDI.

“Compared with the elongation at break (7.2%, 3.9%, and 27.6%) of PLA/PCL blends (6100D, 2003D, and 4060D), the corresponding elongation at break values of PLA/PCL/tri-HDI blends were 151.4,126.3, and 168.1%, respectively.”

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The melting peak of PLA in PLA/PCL blends gradually moves toward the low-temperature zone as the D-lactide content increases, while the cold crystallization peak gradually moves toward the high-temperature zone.

“The melting peak of PLA gradually moved toward the low-temperature zone as the content of D-lactide increased, while the cold crystallization peak gradually moved toward the hightemperature zone (crystallization and melting temperatures for Dlactide contents of 0.5% and 4% were 97.8°C, 117.4°C and 172.1°C, 151.6°C, respectively).”

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For PLA with 4% D-isomer, the PLA/PCL/tri-HDI blend exhibits a high elongation at break (126.3%) without sacrificing mechanical strength (62.9 MPa), comparable to neat PLA.

“For PLA with 4% content of the D-isomer, blends exhibited a high elongation at break (126.3%)without sacrificing mechanical strength (62.9 MPa), which was comparable to that of neat PLA.”

• Also stated in: § 3.3 | Mechanical Properties · plain

  “the corresponding elongation at break values of PLA/PCL/tri-HDI blends were 151.4,126.3, and 168.1%, respectively.”

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After adding compatibilizers, the surface became rougher and PCL droplets were completely wrapped or embedded into the PLA matrix, evidenced by good interfacial adhesion.

“Differently, the surface became rougher and it could be clearly seen that the PCL droplets were completely wrapped or embedded into the PLA matrix, evidenced by good interfacial adhesion, implying that the interphase boundary was apparently changed by the addition of tri-HDI.”

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In 4060D/PCL/tri-HDI, the fractured surface showed a dense PCL phase and undulating PLA matrix with chain bundles featuring tapered crack tips, without distribution of elongated fibers and voids.

“As presented in Figure 8F, the dense PCL phase and undulating PLA matrix with chain bundles featuring tapered crack tips were observed at the fractured surface without the distribution of elongated fibers and voids.”

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After addition of tri-HDI, the crystallization temperature (Tc) of 6100D shows almost no change, while the Tc of 2003D increases from 117.4°C to 126.4°C.

“As shown in Table 2, after the addition of tri-HDI, the T c of 6100D showed almost no change, while the T c of 2003D increased from 117.4°C to 126.4°C.”

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The 2003D/PCL/HDI blend achieved an elongation at break of 170.1% and a tensile strength of 43.4 MPa, exhibiting a higher elongation at break and lower tensile strength compared to the 2003D/PCL/tri-HDI blend.

“The 2003D/PCL/HDI blend achieved an elongation at break of 170.1% and a tensile strength of 43.4 MPa, respectively, exhibiting a higher elongation at break and lower tensile strength compared to the 2003D/PCL/tri-HDI blend.”

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The impact samples of 4060D/PCL/tri-HDI showed partial adhesion and nonbroken behavior during impact testing after adding reactive compatibilizers, while the other PLA/PCL mixtures showed complete fracture.

“In addition, from the photos of the fractured samples inserted in Figure 6, it could be seen that the impact samples of 4060D/PCL/tri-HDI showed partial adhesion and still nonbroken behavior during the impact testing process after adding reactive compatibilizers, while the other PLA/PCL mixture showed complete fracture after impact testing.”

Classified as probably not a substantial claim.

The main difference between the three PLA pellets was the ratio of D-type chiral lactide isomers to the L-type ones, which varied from 0.5% to 12%.

“The main difference between the three PLA pellets was the ratio of D-type chiral lactide isomers to the L-type ones, which varied from 0.5% to 12%.”

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At a PLA/PCL weight ratio of 5:5, the impact strength of 6100D/PCL/tri-HDI and 4060D/PCL/tri-HDI was 16.5 and 64.9 kJ/m2, respectively, approximately 2.2 and 7.5 times higher than the corresponding samples without tri-HDI.

“High toughness was achieved for the blend consisting of 50% PLA and 50% PCL, with an impact strength as high as 64.9 kJ/m 2 , which was 3.9 and 5.7 times higher than that of 6100D and 2003D, whose impact strength was 16.5 and 11.3 kJ/m 2 , respectively.”

The quote only partly states this claim.

Blends of amorphous PLA exhibit lower complex viscosity and melt strength than blends of crystalline PLA.

“Dynamic rheological analysis showed that the blends of amorphous PLA exhibited lower complex viscosity and melt strength.”

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For neat 4060D/PCL blend, the cross-section became rough and showed obvious fiber stretching.

“For neat 4060D/PCL blend, the cross-section became rough and showed obvious fiber stretching, implying that robust deformation occurred during stretching (Figure 8C).”

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The crystallization degrees of 6100D and 2003D were much higher than that of 4060D, which was completely amorphous.

“The crystallization degrees of the 6100D and 2003D were much higher than that of 4060D, which was completely amorphous.”

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The gel contents of 6100D/PCL, 2003D/PCL, and 4060D/PCL blends were 23.4%, 32.6%, and 19.3%, respectively.

“Under the same reaction conditions, the calculated gel contents of 6100D/PCL, 2003D/PCL, and 4060D/ PCL were 23.4%, 32.6%, and 19.3%, respectively.”

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The crystallinity of PLA/PCL/tri-HDI blends with D-lactide content of 0.5% and 4% after adding reactive compatibilizers were 47.1% and 17.5%, respectively, slightly lower than that of PLA/PCL mixtures without tri-HDI addition (67.0% and 23.1%), indicating that tri-HDI confined the crystallization of PLA.

“The crystallinity of PLA/PCL/ tri-HDI blends with D-lactide content of 0.5% and 4% after adding reactive compatibilizers were 47.1% and 17.5%, respectively, slightly lower than that of PLA/PCL mixtures without tri-HDI addition (67.0% and 23.1%), indicating that tri-HDI confined the crystallization of PLA.”

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FTIR spectra confirmed the reaction of tri-HDI with PLA and PCL, and insoluble matter in solvent revealed its cross-linked network structure of 3-arm star PLAx-PCLy copolymers.

“FTIR spectra confirmed the reaction of tri-HDI with PLA and PCL, and insoluble matter in solvent further revealed its cross-linked network structure of 3-arm star PLA x -PCL y copolymers.”

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The decomposition temperature range of PLA was approximately 300°C-400°C, while the decomposition temperature range of PCL was approximately 350°C-450°C.

“From Figure 12, the decomposition temperature range of PLA was approximately 300°C-400°C, while the decomposition temperature range of PCL was approximately 350°C-450°C.”

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As D-isomer content increased to 12%, the sea-island structure was less obvious and the PCL phase was buried in the PLA phase.

“As D-isomer content increased to 12%, the seaisland structure was less obvious and the PCL phase was buried in the PLA phase.”

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The impact strength of the 4060D/PCL/tri-HDI blends was greater than that of the blends prepared by 6001D and 2003D, with partial break impact behavior.

“The impact strength of the 4060D/PCL/tri-HDI blends was greater than that of the blends prepared by 6001D and 2003D, with partial break impact behavior.”

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The presence of the cross-linked network limited local crack propagation and enhanced impact strength by dispersing stress.

“The presence of the cross-linked network helped to limit the local crack propagation and enhanced the overall impact strength by dispersing stress.”

Classified as probably not a substantial claim. May combine two claims.

PCL has multiple repeated methylene units between ester bonds, a more flexible molecular structure, and a lower glass transition temperature (about -60°C), making it one of the materials with the highest ductility among similar materials.

“On the contrary, PCL has multiple repeated methylene units between ester bonds with a more flexible molecular structure and a lower glass transition temperature (about -60°C), which makes it one of the materials with the highest ductility among similar materials [32].”

• cites [32] 32. E. Archer, M. Torretti, and S. Madbouly, "Biodegradable Polycapro- lactone (PCL) Based Polymer and Composites," Physical Sciences Re- views 8 (2023): 4391. sourceNot checked — no full text of the source

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The actual impact strength of 4060D/PCL/tri-HDI should be higher than 14.7 kJ/m2 because the corresponding specimens were only partially broken.

“It was worth noting that the actual impact strength of 4060D/PCL/tri-HDI should be higher than 14.7 kJ/m 2 because the corresponding specimens were only partially broken.”

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The higher impact strength of 4060D/PCL/tri-HDI compared to 6100D/PCL/tri-HDI was because 4060D was amorphous and 6100D was crystalline.

“This was because 4060D was amorphous and 6100D was crystalline.”

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In 2003D/PCL/tri-HDI, the tensile strength was higher than that of 2003D/PCL because of the higher degree of crosslinking and the relatively minor effect of the cross-linked structure on PLA crystallinity.

“In 2003D/PCL/tri-HDI, because of the higher degree of crosslinking and the relatively minor effect of the cross-linked structure on PLA crystallinity, the tensile strength of 2003D/PCL/tri-HDI was higher than that of 2003D/PCL.”

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Excessive crystallinity may cause the mixture to become too rigid, making it more prone to brittle fracture under impact, leading to reduced notched impact strength.

“An excessive crystallinity may cause the mixture to become too rigid, making it more prone to brittle fracture under impact, which led to a reduction in notched impact strength.”

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The miscibility of PCL and PLA, morphology of phase boundaries, and crystallization morphology in blends were altered by the addition of tri-HDI and the optical purities of PLA, thus effectively affecting the above-mentioned mechanical properties.

“In summary, the miscibility of PCL and PLA, morphology of phase boundaries, and crystallization morphology in blends were altered by the addition of tri-HDI and the optical purities of PLA, thus effectively affecting the above-mentioned mechanical properties.”

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The optical purity of PLA significantly affects its crystallization ability and glass transition temperature, and would also affect physical properties such as molecular chain density, mechanical, and rheological properties.

“Since the optical purity of PLA exhibits a significant impact on the crystallization ability and glass transition temperature, it would also affect the physical properties of PLA, such as molecular chain density, mechanical, and rheological properties [39,40].”

• cites [39] 39. J. R. Sarasua, A. L. Arraiza, P. Balerdi, and I. Maiza, "Crystallin- ity and Mechanical Properties of Optically Pure Polylactides and Their Blends," Polymer Engineering and Science 45, no. 5 (2005): 745. sourceNot checked — no full text of the source
• cites [40] 40. H. Xu, S. Tang, J. Chen, P. M. Yin, W. M. Pu, and Y. Lu, "Thermal and Phase-Separation Behavior of Injection-Molded Poly (L-Lactic Acid)/Poly (D-Lactic Acid) Blends With Moderate Optical Purity," Poly- mer Bulletin 68 (2012): 1135. sourceNot checked — no full text of the source

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Compared with HDI, tri-HDI is a trimer of HDI containing three isocyanate groups; the additional isocyanate groups increase cross-linking density and form a more complex polymer network, leading to an improvement in tensile strength but a reduction in elongation at break.

“Compared with HDI, tri-HDI is a trimer of HDI containing three isocyanate groups.The additional isocyanate groups can significantly increase the cross-linking density and form a more complex polymer network, leading to an improvement in tensile strength but a reduction in elongation at break.”

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In 4060D/PCL/tri-HDI, the tensile strength did not decrease compared to 4060D/PCL because 4060D was amorphous and the cross-linked network enhanced interactions between molecular chains.

“In 4060D/PCL/tri-HDI, since 4060D was amorphous, the cross-linked network did not affect the crystallinity of PLA.The presence of the cross-linked network enhanced the interactions between the molecular chains, resulting in the tensile strength of 4060D/PCL/tri-HDI not decreasing compared to 4060D/PCL [51].”

• cites [51] 51. H. B. Chai, Y. Chang, Y. C. Zhang, et al., "The Fabrication of Poly- lactide/Cellulose Nanocomposites With Enhanced Crystallization and Mechanical Properties," International Journal of Biological Macromole- cules 155 (2020): 1578. sourceNot checked — no full text of the source

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Reducing the number of large spherulites or increasing a glassy amorphous region will reduce opportunities for crack formation and propagation, thus helping to improve toughness of materials.

“Reducing the number of large spherulites or increasing a glassy amorphous region will reduce the opportunities for crack formation and propagation, thus helping to improve the toughness of materials.”

• AssumptionRests on an assumption: Big spherulites are weak points in materials and easily become starting points of cracks.

Classified as probably not a substantial claim.

The as-formed fibrils were supposed to prevent and withstand the applied stress.

“The as-formed fibrils were supposed to prevent and withstand the applied stress.”

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Li et al. [52] prepared PLA/PCL/HDI blends by melt blending; when the weight ratio of PLA to PCL was 70/30, the tensile stress of the blend was below 25 MPa and the elongation at break was below 30%.

“Li et al. [52] prepared PLA/PCL/HDI blends by melt blending.The results showed that when the weight ratio of PLA to PCL was 70/30, the tensile stress of the blend was below 25 MPa and the elongation at break was below 30%.”

• cites [52] 52. H. C. Li, X. Zhang, J. J. Wang, Q. Xing, R. Li, and X. Dong, "Toward Highly Toughened Polylactide/Polycaprolactone-Based Polyurethane Blends With Shape Memory Property via Reactive Blending," Journal of Applied Polymer Science 142 (2024): 56490. sourceNot checked — no full text of the source

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The cross-linked copolymer worked together with the non-reacted PCL phase, consuming abundant energy through plastic deformation, resulting in improved toughness of the PLA/PCL/tri-HDI blend.

“It worked together with the non-reacted PCL phase, consuming abundant energy through plastic deformation, resulting in an improvement in the toughness of the PLA/PCL/tri-HDI blend.”

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The compatibilizer added to the blend can undergo an in situ reaction with the participating polymers, generating in situ block copolymers as reactive compatibilizers, effectively decreasing the intermural tension between the two polymer components and facilitating their compatibility.

“The compatibilizer added to the blend can undergo an in situ reaction with the participating polymers, generating”

• cites [29] 29. H. Wang, W. Dong, and Y. Li, "Compatibilization of Immiscible Polymer Blends Using in Situ Formed Janus Nanomicelles by Reactive Blending," ACS Macro Letters 4 (2015): 1398. sourceNot checked — no full text of the source

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The cross-linked structure enhanced overall interfacial bonding and toughness of the material.

“After the addition of tri-HDI, a cross-linked structure formed within the blend, enhancing the overall interfacial bonding and toughness of the material.”

Classified as probably not a substantial claim. May combine two claims.

Better interfacial compatibility between blend materials can be achieved through the addition of compatibilizers, resulting in significant performance improvement of the blends.

“It has been reported that better interfacial compatibility between blend materials can be achieved through the addition of compatibilizers, ultimately resulting in a significant performance improvement of the blends.”

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The 3-arm star PLAx-PCLy cross-linked copolymer obtained from in situ reaction was uniformly distributed in the two-phase structure of PLA and PCL, improving interfacial interaction and making the overall structure more difficult to separate.

“This was because 3-arm star PLA x -PCL y cross-linked copolymer obtained from in situ reaction was uniformly distributed in the two-phase structure of PLA and PCL, improving interfacial interaction and making the overall structure of the blend more difficult to separate.”

Classified as probably not a substantial claim.

The crystallization rate and crystallization ability of PLA decrease due to chain-folding being disturbed by stereoregularity defects.

“The crystallization rate and crystallization ability of PLA were supposed to decrease due to the chain-folding of PLA being disturbed by the stereoregularity defects [38].”

• cites [38] 38. H. Tsuji and Y. Ikada, "Stereocomplex Formation Between Enantio- meric Poly(Lactic Acid)s. 6. Binary Blends From Copolymers," Macro- molecules 25 (1992): 5719-5723. sourceNot checked — no full text of the source

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Due to the cross-linked structure of 3-arm star PLAx-PCLy, the material became harder and solidified because the cross-linked structure prevented relative movement between molecules, enhancing rigidity and strength.

“Due to the cross-linked structure of 3-arm star PLA x -PCL y , the material became harder and solidified because the cross-linked structure could prevent relative movement between molecules, thereby enhancing the rigidity and strength of the material.”

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The interfacial adhesion of the blend was improved by cross-linked copolymers, endowing PLA/PCL/tri-HDI blends with excellent melt strength and mechanical properties.

“The interfacial adhesion of the blend was improved by cross-linked copolymers, endowing PLA/ PCL/tri-HDI blends with excellent melt strength and mechanical properties.”

May combine two claims.

At lower angular frequencies, molecular chains had enough time to respond to external strain, leading to viscous characteristics and relatively low G′.

“This was because, at lower angular frequencies, the molecular chains had enough time to respond to external strain, which led to the molecular chains exhibiting viscous characteristics, resulting in a relatively low G′.”

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Tri-HDI, as a reactive compatibilizer, could effectively improve the interfacial compatibility of PLA/PCL blends without affecting their thermal stability.

“This meant that tri-HDI, as a reactive compatibilizer, could effectively improve the interfacial compatibility of PLA/PCL blends without affecting their thermal stability.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A large G′ indicated higher melt strength when the angular frequency was in the low region.

“Typically, a large G′ indicated higher melt strength when the angular frequency was in the low region [53].”

• cites [53] 53. J. B. Hu, W. B. Wang, X. Y. Liu, et al., "Synergistic Enhancement of Poly(Lactide) Melt Strength via Copolymerization and Multi-Arm Branching Strategy," International Journal of Biological Macromole- cules 280 (2024): 136161. 26424169, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/pol.20250032 by Mount Vernon Nazarene University, Wiley Online Library on [28/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License sourceNot checked — no full text of the source

May combine two claims.

Appropriate selection of reactive additives, optical purities of PLA, and weight ratio of PLA/PCL in this work resulted in PLA/PCL blends with a good balance of mechanical properties, which would be helpful for understanding the development of high-performance PLA/PCL blends.

“Appropriate selection of reactive additives, optical purities of PLA, and weight ratio of PLA/PCL in this work had resulted in PLA/PCL blends with a good balance of mechanical properties, which would be helpful for the understanding of the development of high-performance PLA/PCL blends.”

May combine two claims.

As angular frequency increased, the strain action time on molecular chains became shorter and their response time became insufficient, resulting in more rigid characteristics and an increase in G′.

“As the angular frequency increased, the strain action time on the molecular chains became shorter, and the response time of the molecular chains gradually became insufficient to keep up with the speed of external changes, resulting in a more rigid characteristic and an increase in G′.”

May combine two claims.

Due to the increase in D-lactide content, different chiral molecules in PLA were randomly arranged, resulting in decreased molecular chain order, reduced number and size of crystallization regions, decreased crystallinity, and decreased rigidity of the blend.

“Due to the increase in D-lactide content, different chiral molecules in PLA were randomly arranged, resulting in a decrease in molecular chain order, a reduction in the number and size of crystallization regions, and a decrease in crystallinity, leading to a decrease in the rigidity of the blend.”

• AssumptionRests on an assumption: The degree of crystallinity and molecular arrangement of polymer chains significantly impact the storage modulus G′ of materials.
• AssumptionRests on an assumption: Higher crystallinity in polymer materials is usually manifested as more ordered molecular chains forming crystalline regions, which provide additional strength to resist external strain.
• AssumptionRests on an assumption: More ordered molecular arrangement strengthens intermolecular interactions, enhancing strength and rigidity and increasing G′.