Composites of a PLA with SBA-15 mesoporous silica: Polymorphism and properties after isothermal cold crystallization

Díez‐Rodríguez, Tamara M.; Blázquez‐Blázquez, Enrique; Martínez, Juan Carlos; Pérez, Ernesto; Cerrada, María L.

doi:10.1016/j.polymer.2022.124515

Cited by 15 publications

(22 citation statements)

References 62 publications

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“…In addition to the lower values (around 12–15 °C lower) for T m 1 and T m 2 observed in PLLA4 and PLLA4SBA9 due to the smaller chain regularity, other features can be deduced. On one hand, the temperatures at which the α’ polymorph is developed during isothermal crystallization from the glass are also considerably lower in PLLA4 and PLLA4SBA9 than in PLLA2 and PLLA2SBA8, being in the former from 70 to 80 °C (since the majority of crystals at 85 °C are α-type [ 58 ]) while its development in PLLA2 and PLLA2SBA8 takes place in the range from around 95 to 105 °C. This lowering of temperatures makes the formation interval of α’ crystals in the PLLA4 overlap with the glass transition.…”

Section: Resultsmentioning

confidence: 99%

Influence of Content in D Isomer and Incorporation of SBA-15 Silica on the Crystallization Ability and Mechanical Properties in PLLA Based Materials

et al. 2022

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Two L-rich polylactides (PLLA) with distinct contents in D isomer and their composites with an intermediate amount of mesoporous Santa Barbara Amorphous-15 (SBA-15) (about 9 wt.%) particles were attained by melt extrusion for the evaluation of the effect of content in D isomer and incorporation of mesoporous silica on the structural PLLA features and on their ultimate mechanical performance. For that, samples have been crystallized under dynamic and isothermal tests (from the melt and from the glassy states). The results from DSC and X-ray diffraction show obtainment of the pure α’ and α modifications at different intervals of crystallization temperature depending on the D steroisomer amount of the PLLA used. Furthermore, several phase transitions are observed depending on the crystallinity reached and the polymorphs developed during the isothermal crystallization from the glass: an additional cold crystallization, the α’/α transformation and the subsequent melting process, appearing all of them at temperatures clearly dependent on the D content. Rigidity, measured through microhardness in amorphous samples, is also affected by the D isomer and the presence of SBA-15 particles. Reinforcement effect of mesoporous silica is relatively more important in the matrix with the highest D content.

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Section: Resultsmentioning

confidence: 99%

Influence of Content in D Isomer and Incorporation of SBA-15 Silica on the Crystallization Ability and Mechanical Properties in PLLA Based Materials

et al. 2022

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“…It has been described in literature that the presence of SBA-15 particles does not affect the development of one or another PLA crystalline lattice. [29,30] Content in the PLA of D stereoisomer is the key parameter. [40] As mentioned above, the disordered 𝛼′ modification is attained for this PLA grade at temperatures below ≈90 °C, [40] while the pure 𝛼 form is achieved for temperatures above ≈110 °C, observing mixed proportions of the two polymorphs in the temperature interval in between those two values.…”

Section: Resultsmentioning

confidence: 99%

“…The X‐ray crystallinity was assessed as the ratio of normalized areas of the crystalline peaks and the total area of the background‐corrected diffraction profile. [ 30 ] The area of pure crystalline peaks was attained from the normalized area of total diffraction profile after subtracting the normalized scattering area of the amorphous halo, to which a coefficient was applied in order to achieve the perfect fit at the beginning and the end of the interval considered at each experimental profile. This amorphous halo is taken from the X‐ray pattern of a fully amorphous sample, obtained from the compression‐molded films prepared at high cooling rates from the molten state.…”

Section: Methodsmentioning

confidence: 99%

“…An effect of the mesoporous Santa Barbara Amorphous‐15 (designated commonly as SBA‐15) silica was recently reported in the PLA crystallization for extruded composites. Formation of PLA crystallites was evaluated through dynamic and isothermal experiments from the molten [ 29 ] or glassy [ 30 ] states. These mesoporous particles are very interesting inorganic materials since they show ordered arrangements developed during their synthesis that consist of hollow channels, with diameters ranging from 7 to 10 nm, within the particles.…”

Section: Introductionmentioning

confidence: 99%

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Synergistic Effect of Mesoporous SBA‐15 Particles and Processing Strategy for Improving PLA Crystallization Capability in their Composites

Díez‐Rodríguez

Blázquez‐Blázquez

Barranco‐García

et al. 2022

Macro Materials & Eng

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Several composites based on an L‐rich poly(lactic acid) (PLA) and mesoporous Santa Barbara Amorphous‐15 (SBA‐15) are prepared by their addition through two methods: solution‐mixed (solvent casting) or melt‐mixed (extrusion). Subsequently, films of all the materials are processed by compression molding. The nucleating capacity of silica on PLA crystallization is found to be strongly dependent on protocol used for SBA‐15 incorporation. Thus, mesoporous particles induce some PLA ordering in composites when extrusion is used but nucleating ability is much more remarkable when PLA‐SBA composites are prepared by SBA‐15 addition through casting, PLA crystallization being observed on cooling even at 40 °C min−1. Crystallinity, crystallization temperature, and polymorphs developed are also dependent on preparation method and cooling rate. Mechanical properties are tested on the just compressed‐molded films. At a given SBA‐15 content, the melt‐mixed composite is less stiff than the solution‐mixed material despite both are completely amorphous. Accordingly, microhardness shows a smaller value in the former. For the solution‐mixed approach, a partial coating (either external or internal) of the silica particles by PLA chains is suggested to occur during the first preparation stage, enabling a better transfer of reinforcement exerted by SBA‐15 silica into the PLA matrix.

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“…Recently, the mesoporous silica has been used as well. In particular, the SBA-15 particles have been proved to play an important role in the PLA crystallization in composites prepared either by melt extrusion [ 17 , 18 ] or by solution mixing [ 19 ]. Mesoporous SBA-15 is constituted by ordered hexagonal arrangements within the particles, which are developed during the synthesis and consist in hollow channels with diameters from around 7 to 10 nm [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

Combined Effects from Dual Incorporation of ATBC as Plasticizer and Mesoporous MCM-41 as Nucleating Agent on the PLA Isothermal Crystallization in Environmentally-Friendly Ternary Composite Systems

et al. 2023

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Different materials, based on an L-rich polylactide (PLA) as matrix, acetyl tri-n-butyl citrate (ATBC) as plasticizer, and mesoporous Mobile Crystalline Material.41 (MCM-41) particles as nucleating agent, were attained by melt extrusion. These materials are constituted by (a) binary blends of PLA and ATBC with different contents of the latest; (b) a dual compound of PLA and a given amount of MCM-41 silica (5 wt.%); and (c) ternary composites that include PLA, ATBC at several compositions and mesoporous MCM-41 at 5 wt.%. Influence of the incorporation of the plasticizer and nucleating particles has been comprehensively analyzed on the different phase transitions: glass transition, cold crystallization, melt crystallization and melting processes. Presence of both additives moves down the temperature at which PLA phase transitions take place, while allowing the PLA crystallization from the melt at 10 °C/min in the composites. This tridimensional ordering is not noticeable in the pristine PLA matrix and, accordingly, PLA crystallization rate is considerably increased under dynamic conditions and also after isothermal crystallization from either the melt or the glassy state. An important synergistic effect of dual action of ATBC and MCM-41 has been, therefore, found.

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Composites of a PLA with SBA-15 mesoporous silica: Polymorphism and properties after isothermal cold crystallization

Cited by 15 publications

References 62 publications

Influence of Content in D Isomer and Incorporation of SBA-15 Silica on the Crystallization Ability and Mechanical Properties in PLLA Based Materials

Influence of Content in D Isomer and Incorporation of SBA-15 Silica on the Crystallization Ability and Mechanical Properties in PLLA Based Materials

Synergistic Effect of Mesoporous SBA‐15 Particles and Processing Strategy for Improving PLA Crystallization Capability in their Composites

Combined Effects from Dual Incorporation of ATBC as Plasticizer and Mesoporous MCM-41 as Nucleating Agent on the PLA Isothermal Crystallization in Environmentally-Friendly Ternary Composite Systems

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