Toughening Of Poly Research Articles

Boosting the Strength and Toughness of Polymer Blends via Ligand-Modulated MOFs.

Mechanically robust and tough polymeric materials are in high demand for applications ranging from flexible electronics to aerospace. However, achieving both high toughness and strength in polymers remains a significant challenge due to their inherently contradictory nature. Here, a universal strategy for enhancing the toughness and strength of polymer blends using ligand-modulated metal-organic framework (MOF) nanoparticles is presented, which are engineered to have adjustable hydrophilicity and lipophilicity by varying the types and ratios of ligands. Molecular dynamics (MD) simulations demonstrate that these nanoparticles can effectively regulate the interfaces between chemically distinct polymers based on their amphiphilicity. Remarkably, a mere 0.1wt.% of MOF nanoparticles with optimized amphiphilicity (ML-MOF(5:5)) delivered ≈3.4- and ≈34.1-fold increase in strength and toughness of poly (lactic acid) (PLA)/poly (butylene succinate) (PBS) blend, respectively. Moreover, these amphiphilicity-tailorable MOF nanoparticles universally enhance the mechanical properties of various polymer blends, such as polypropylene (PP)/polyethylene (PE), PP/polystyrene (PS), PLA/poly (butylene adipate-co-terephthalate) (PBAT), and PLA/polycaprolactone (PCL)/PBS. This simple universal method offers significant potential for strengthening and toughening various polymer blends.

Structure and properties of homogeneous toughened poly(vinyl alcohol) blended membrane and exploration of application in membrane separation

Polyvinyl alcohol (PVA) has excellent physical and chemical properties; however, its rigidity easily leads to brittleness and breakage during use. Additionally, due to intramolecular hydrogen bonding, the dense structure of the film limits its application. This research used a self-toughening approach by homogeneously blending PVA 0588 and PVA 0499 with different molecular weights to enhance the toughness of PVA and create a porous structure for broader application in membrane separation. Porous PVA membranes were then produced through mechanical stretching. Rheological testing, differential scanning calorimetry, and dynamic thermomechanical analysis confirmed that the blend system is partially compatible. Mechanical characterization revealed that adding PVA 0499 decreased the tensile modulus, strength, and bending modulus of the blended film but increased the elongation at break, reaching a maximum of 179 %. This result indicates that homogeneous blending effectively achieved PVA self-toughening. After this, the PVA blended membrane underwent mechanical stretching. Results showed that the stretched membrane developed a porous structure with a PVA 0588 content of 60 wt%, yielding a pure water flux of 70.3 L m−2 h−1 MPa−1 and a glucan rejection rate of 91.07 %. The molecular weight cut-off test demonstrated that the resulting porous membrane was suitable for water treatment, effectively filtering substances with a molecular weight of ≥70 kDa. The membrane also exhibited notable antifouling properties. The hydrophilicity and high roughness of the porous membrane facilitated the formation of additional hydrogen bonds between the membrane surface and water molecules, thereby reducing direct contact between pollutants and the membrane surface. This study provides preliminary theoretical and experimental insights into enhancing PVA toughness and expanding its applications in membrane separation. Furthermore, homogeneous blending opens new avenues for improving the mechanical performance of polymers.

Flame-retardant and tough poly(lactic acid) with well-preserved mechanical strength via reactive blending with bio-plasticizer and phosphorus derivative

With sustainable development, advanced poly(lactic acid) (PLA) with superior toughness and flame retardancy is highly demanded in various industries, but the current design strategies often fail to achieve such bioplastics. In this work, flame-retardant and tough PLA bioplastics with well-preserved thermal stability and mechanical strength and enhanced UV resistance and soil degradation are prepared by solvent-free, reactive blending of PLA, bio-based epoxidized soyabean oil (ESO) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO). With the introduction of 10.0 wt% ESO and 3.0 wt% DOPO, the resultant PLA/10E/3D bioplastic has a high tensile strength of 52.8 MPa, with 26.3 times and 67.5 % increases in elongation at break and impact strength compared to those of PLA due to the toughening effect of ESO and the rigid structure of DOPO. The superior toughness of PLA/10E/3D enables it to outperform previous flame-retardant PLA counterparts. PLA/10E/3D achieves a vertical burning (UL-94) V-0 classification and a limiting oxygen index (LOI) of 27.5 %, indicative of satisfactory flame retardancy. Compared with PLA, PLA/10E/3D maintains high thermal stability and shows significantly enhanced UV-protecting and soil degradation properties. Therefore, this work delivers a green and scalable reactive processing method to create flame-retardant, tough yet strong bioplastics with improved soil decomposition and UV resistance, which contributes to sustainable development.

Enhanced compatibility and toughness of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/polycaprolactone blends by ring‐opening polymerization and hydrogen bonding of epoxy‐terminated hyperbranched polyester

AbstractMelt extrusion process was followed in order to improve the high crystallinity and poor toughness of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) blend materials. It was achieved by the incorporation of epoxy‐terminated hyperbranched polyester (EHBP) elastomer into PHBV and polycaprolactone (PCL). EHBP cross‐links PHBV and PCL through ring‐opening polymerization of epoxy‐terminated and carboxyl groups. The mass percentages of EHBP in the PHBV/PCL blends are 1, 2, 3, and 4mass%, which are expressed as 1, 2, 3, and 4 phr in the following text. Therefore, when the EHBP content was 3 phr, the Young's modulus and tensile strength of the blends are increased to 750 and 15 MPa, respectively, which was comparable to the biodegradable polymers used for packaging. Simultaneously, compatibility between PHBV and PCL has been improved and the particle size reduction of blends can be obviously observed in scanning electron microscope (SEM) images. Dynamic mechanical analysis (DMA) analysis revealed that PHBV and PCL showed improved compatibility with each other by the addition of EHBP. Differential scanning calorimetry (DSC) revealed that the decrease of crystallinity of the blend was consistent with the increase in mechanical properties. Additionally, all the bio‐blends show good thermal stability. Food overall migration studies showed that the amount of migration of composite materials in contact with food was also far lower than the national standard value. Therefore, PHBV/PCL/EHBP blends are expected to be used in the field of food packaging.

Biosynthesis of High Toughness Poly(3-Hydroxypropionate)-Based Block Copolymers With Poly(D-2-Hydroxybutyrate) and Poly(D-Lactate) Segments Using Evolved Monomer Sequence-Regulating Polyester Synthase.

This study synthesized poly(3-hydroxypropionate) [P(3HP)]-containing polyhydroxyalkanoate (PHA) block copolymers, P(3HP)-b-P[2-hydroxybutyrate (2HB)] and P(3HP)-b-P(D-lactate) (PDLA), using Escherichia coli. The cells expressing an evolved sequence-regulating PHA synthase, PhaCARNDFH, and propionyl-CoA transferase were cultured with the supplementation of the corresponding monomer precursors in the medium. The block structure of P(3HP)-b-PDLA was confirmed by proton nuclear magnetic resonance analysis and solvent fractionation. The molecular weights of the polymers were in the range of 0.8-2.8 × 105. The solvent-cast polymer films were subjected to isothermal treatment to promote phase separation and crystallization and were subsequently melt-quenched to produce an amorphous phase. The melt-quenched P(3HP)-b-P(2HB) film exhibited a high elongation at break (1153%), resulting in a toughness of 181 MJ/m3. The solvent-cast film of P(3HP)-b-65 mol% PDLA exhibited partial elastic deformation, in which the P(3HP) phase functioned as a soft segment. The melt-quenching of the polymer resulted in embrittlement presumably due to the high lactate fraction. Overall, the P(3HP)-based block copolymers exhibited several mechanical properties depending on the higher-order structure of the polymer and the properties of the P(2-hydroxyalkanoate) segments. This study findings show that P(3HP)-b-P(2HB) and P(3HP)-b-PDLA can function excellently if their microstructures are properly controlled.

Shock wave energy dissipation in strong and tough poly(dimethylsiloxane) composites with controlled microstructure

Of particular significance is to design materials mitigating shock waves induced by blast and high-speed impact for protecting people and structures. Polymer composites possess remarkable energy-dissipation performance, but there is a lack of awareness about precise regulation of energy dissipation through control over material microstructure. Herein, strong and tough poly(dimethylsiloxane) (PDMS) composites with particle-mediated microstructure were devised for shock wave energy dissipation. Morphological observation revealed that composites with agglomerate structure and homodisperse structure were obtained by adjusting particle surface chemistry. Compared with pure PDMS, strength and toughness for composites with agglomerate structure increased by 65 % and 280 %, respectively, while these characteristics for composites with homodisperse structure rised by 90 % and 433 %, respectively. During laser-induced shock compression, composites with homodisperse structure exhibited better energy dissipation ability than composites with agglomerate structure. In comparison with pure PDMS, the shock wave peak pressure for composites with agglomerate structure and homodisperse structure reduced by up to 43 % and 75 %, respectively. As for composites with agglomerate structure, the mechanism for shock wave energy dissipation derived from fast segmental dynamics and low glass transition temperature of PDMS matrix, agglomerate breakup and wave scattering at agglomerate/matrix interfaces. The raised energy dissipation effect for composites with homodisperse structure rooted in enhanced reflections of shock waves at increased particle/matrix interfaces. These findings provide a promising strategy to construct energy-adsorbing materials with controlled microstructure for personnel and equipment protection.

Ultrastretchable and Tough Poly(ionic liquid) Elastomer with Strain-Stiffening Ability Enabled by Strong/Weak Ionic Interactions

Ultrastretchable and Tough Poly(ionic liquid) Elastomer with Strain-Stiffening Ability Enabled by Strong/Weak Ionic Interactions

Strong and tough poly(vinyl alcohol)/xanthan gum-based ionic conducting hydrogel enabled through the synergistic effect of ion cross-linking and salting out

The mechanical properties of ionic conductive hydrogels (ICHs) are generally inadequate, leading to their susceptibility to breakage under external forces and consequently resulting in the failure of flexible electronic devices. In this work, a simple and convenient strategy was proposed based on the synergistic effect of ion cross-linking and salting out, in which the hydrogels consisting of polyvinyl alcohol (PVA) and xanthan gum (XG) were immersed in zinc sulfate (ZnSO4) solution to obtain ICHs with exceptional mechanical properties. The salt-out effects between PVA chains and SO42− ions along with the cross-linked network of XG chains and Zn2+ ions contribute to the desirable mechanical properties of ICHs. Notably, the mechanical properties of ICHs can be adjusted by changing the concentration of ZnSO4 solution. Consequently, the optimum fracture stress and the fracture energy can reach 3.38 MPa and 12.13 KJ m−2, respectively. Moreover, the ICHs demonstrated a favorable sensitivity (up to 2.05) when utilized as a strain sensor, exhibiting an accurate detection of human body movements across various amplitudes.

Weathered coal-based carbon dots modified by organic amine for enhanced crystallinity and toughness of poly(lactic acid) film

Poly(lactic acid) (PLA) has its own limitations in terms of slow crystallization rate and low crystallinity during processing, resulting in poor toughness and thermal stability, which seriously restricts the practical application of PLA. Blending nanoparticles into the PLA matrix is an effective way to improve PLA crystallization. In this study, carbon dots (CDs) were prepared by green oxidation using weathered coal as carbon source and then surface-modified with dodecylamine (DDA) and octadecylamine (ODA). Modified CDs (MCDs)/PLA composite films were prepared using MCDs as filler to improve the crystallinity and toughness of PLA films. The results showed that the improvement effect of ODA-modified CDs (ODACDs) was better than that of DDA-modified CDs (DDACDs). The crystallinity of PLA composite film (0.05 wt% ODACDs) was increased from 7.20% (pure PLA film) to 35.44%, and its elongation at break was increased by 5.01 times compared with that of the pure PLA film. Moreover, thermogravimetric analysis suggested that the thermal stability of MCDs/PLA films was also improved. The results of simultaneous rheology and in-situ FTIR analysis as well as molecular dynamics simulations confirmed that MCDs had a strong interaction with PLA molecules, which promoted the crystallization of PLA film, thereby improving its toughness and thermal stability.

The effect of dynamic vulcanization on the morphology and biodegradability of super toughened poly(lactic acid)/unsaturated poly(ether-ester) blends

Preparing a super-tough polylactic acid (PLA) material while maintaining its biodegradability is a significant challenge. This study synthesized a biodegradable unsaturated poly(butylene succinate-co-fumarate)-poly(ethylene glycol) multiblock copolymer (PBSFG) and dynamically vulcanized it with PLA to obtain super-tough blends. The PBSFG self-vulcanized and formed a crosslinked “hard-soft” core-shell rubber phase in the blending process, where the PBSF segment acted as the core and PEG as the shell. As a result, the elongation at break and notched Izod impact strength of PLA increased significantly from 3 % to 66 % and from 3.2 to 58.0 kJ/m2, respectively. Furthermore, adding a small amount of dicumyl peroxide (DCP) promoted dynamic vulcanization and improved the compatibility between PLA and PBSFG. With the addition of 0.03 % DCP, the elongation at break and notched Izod impact strength of PLA/PBSFG were further increased to 218 % and 88.9 kJ/m2, respectively. Meanwhile, the crystallization rate of PLA was enhanced by the addition of PBSFG and DCP. The PLA/PBSFG blends also degraded in a proteinase K Tris-HCl buffered buffer solution. Finally, fully biodegradable and super-tough PLA blends were achieved.

Fabrication high toughness poly(butylene adipate-co-terephthalate)/thermoplastic starch composites via melt compounding with ethylene-methyl acrylate-glycidyl methacrylate

The preparation of biodegradable composites with high toughness and low cost is of great significance for their application and promotion in the packaging field. As a renewable and biodegradable material with abundant sources, the inclusion of starch in biodegradable composites can significantly reduce costs. However, the poor compatibility between starch and matrix severely limits its large-scale practical application. In this work, the poly(butylene adipate-co-terephthalate)/thermoplastic starch/ethylene-methyl acrylate-glycidyl methacrylate (PBAT/TPS/EGMA) blends with high toughness were prepared by melt compounding. The elongation at break increased significantly from 533 ± 125 % for the PBAT/TPS(60/40) blend to 1188 ± 28 % for the PBAT/TPS/EGMA(60/40/2) blend. According to the analysis of Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscope (SEM), the toughness improvement brought about by the addition of EGMA can be attributed to the enhanced compatibility between PBAT and TPS and the refinement of TPS particle size. The knowledge obtained from this study provides a method to enhance the toughness of biodegradable polymer composites with high TPS loading, which will facilitate the practical application of starch in the packing field.

Toughening of poly(lactic acid) (PLA) with poly(butylene adipate-co-terephthalate) (PBAT): a morphological, thermal, mechanical, and degradation evaluation in a simulated marine environment

Toughening of poly(lactic acid) (PLA) with poly(butylene adipate-co-terephthalate) (PBAT): a morphological, thermal, mechanical, and degradation evaluation in a simulated marine environment

A highly-crosslinked phthalonitrile modified bismaleimide-triazine resin for PCB substrates: The synergistic effect on curing behavior and properties

In view of the problems of difficult processing and poor toughness, bismaleimide-triazine (BT) resin was modified by the 4-(4-amino-phenoxy)phthalonitrile (4-APN). The effect of 4-APN on the curing behavior of BT resin was investigated, followed by the calculated activation energy. The possible curing mechanism of this ternary system was also proposed, with the further study of the relationship between chemical structures and properties. The results showed that 4-APN can increase the reactivity and decrease the curing temperature of BT resin. Meanwhile, due to the fact that 4-APN exerted a thermal synergistic curing effect on the BT resin, poly(BT/APN)s with a high crosslinking density exhibited the superior overall performance. Concretely, the high heat-resistance of poly(BT/APN)s was displayed, especially the glass transition temperature up to 347 ℃ of poly(BT/30APN). More intriguingly, poly(BT/APN)s with a high breakdown strength possessed better insulation properties, and the dielectric constant and loss reduced to 3 and 0.005 (1 MHz), respectively, while remaining a good stability at high temperature. Additionally, the moisture resistance and toughness of poly(BT/APN)s were also significantly improved. Based on these merits, poly(BT/APN)s can be considered as an ideal material for microelectronics.

An effective DLP 3D printing strategy of high strength and toughness cellulose hydrogel towards strain sensing

Photocurable 3D printing technology has outperformed extrusion-based 3D printing technology in material adaptability, resolution, and printing rate, yet is still limited by the insecure preparation and selection of photoinitiators and thus less reported. In this work, we developed a printable hydrogel that can effectively facilitate various solid or hollow structures and even lattice structures. The chemical and physical dual-crosslinking strategy combined with cellulose nanofibers (CNF) significantly improved the strength and toughness of photocurable 3D printed hydrogels. In this study, the tensile breaking strength, Young's modulus, and toughness of poly(acrylamide-co-acrylic acid)D/cellulose nanofiber (PAM-co-PAA)D/CNF hydrogels were 375 %, 203 % and 544 % higher than those of the traditional single chemical crosslinked (PAM-co-PAA)S hydrogels, respectively. Notably, its outstanding compressive elasticity enabled it to recover under 90 % strain compression (about 4.12 MPa). Resultantly, the proposed hydrogel can be utilized as a flexible strain sensor to monitor the motions of human movements, such as the bending of fingers, wrists, and arms, and even the vibration of a speaking throat. The output of electrical signals can still be collected through strain even under the condition of energy shortage. In addition, photocurable 3D printing technology can provide customized services for hydrogel-based e-skin, such as hydrogel-based bracelets, fingerstall, and finger joint sleeves.

Generation of Tough Poly(glycolic acid) (PGA)/Poly(butylene succinate-co-butylene adipate) (PBSA) Films with High Gas Barrier Performance through In situ Nanofibrillation of PBSA under an Elongational Flow Field

Generation of Tough Poly(glycolic acid) (PGA)/Poly(butylene succinate-co-butylene adipate) (PBSA) Films with High Gas Barrier Performance through In situ Nanofibrillation of PBSA under an Elongational Flow Field

Cyclic Polyphenylene Sulfide as Additive to Improve the Mechanical Properties of Polystyrene-Based Materials

Cyclic polyphenylene sulfide (PPS) is an unavoidable byproduct of the preparation of linear PPS, one of the most important engineering plastics. Turning the waste into treasure is the best way to address byproducts, prevent pollution, and save energy and resources. Cyclic PPS’s potential to be used in supramolecular chemistry was proven as an additive to enhance the mechanical properties of polystyrene (PS)-based materials. After the addition of cyclic PPS, the toughness of poly(styrene-co-ethyl acrylate) (PS-PEA) was approximately 4 times that of PS, and the value of Young’s modulus saw a slight increase. Cyclic PPS was found to form reversible and movable cross-links with PS-PEA and increase the homogeneity of PS-PEA. Thus, the results of this study provide not only a way to make use of cyclic PPS but also an easy and practical method to prepare reinforced PS-based polymers.

Construction of fully biodegradable poly(L-lactic acid)/poly(D-lactic acid)-poly(lactide-co-caprolactone) block polymer films: Viscoelasticity, processability and flexibility

Development of biodegradable polymer films is essential for sustainable energy conservation and ecological protection. In this work, to improve the processability and toughness of poly(lactic acid) (PLA) films, poly(lactide-co-caprolactone) (PLCL) segments were introduced into poly(L-lactic acid) (PLLA)/poly(D-lactic acid) (PDLA) chains via chain branching reactions during reactive processing, and fully biodegradable/flexible PLLA/D-PLCL block polymer with long-chain branches and stereocomplex (SC) crystalline structure was prepared. Compared with neat PLLA, PLLA/D-PLCL exhibited much higher complex viscosity/storage modulus, lower tanδ values in terminal region and obvious strain-hardening behavior. Through biaxial drawing, PLLA/D-PLCL films were prepared, which showed improved uniformity and non-preferred orientation. With increasing draw ratio, the total crystallinity (Xc) and Xc for SC crystal both increased. By introduction of PDLA, the two phases of PLLA and PLCL penetrated and entangled with each other, and the phase structure transformed from “sea-island” structure to “co-continuous network” structure, which was beneficial for exerting the toughening effect of flexible PLCL molecules on PLA matrix. The tensile strength and elongation at break of PLLA/D-PLCL films increased from 51.87 MPa and 28.22 % of neat PLLA film to 70.82 MPa and 148.28 %. This work provided a new strategy for developing fully biodegradable polymer films with high performance.

Mesenchymal Stem Cells Sense the Toughness of Nanomaterials and Interfaces.

Stem cells are known to sense and respond to the mechanical properties of biomaterials. In turn, cells exert forces on their environment that can lead to striking changes in shape, size and contraction of associated tissues, and may result in mechanical disruption and functional failure. However, no study has so far correlated stem cell phenotype and biomaterials toughness. Indeed, disentangling toughness-mediated cell response from other mechanosensing processes has remained elusive as it is particularly challenging to uncouple Youngs' or shear moduli from toughness, within a range relevant to cell-generated forces. In this report, it is shown how the design of the macromolecular architecture of polymer nanosheets regulates interfacial toughness, independently of interfacial shear storage modulus, and how this controls the expansion of mesenchymal stem cells at liquid interfaces. The viscoelasticity and toughness of poly(l-lysine) nanosheets assembled at liquid-liquid interfaces is characterised via interfacial shear rheology. The local (microscale) mechanics of nanosheets are characterised via magnetic tweezer-assisted interfacial microrheology and the thickness of these assemblies is determined from in situ ellipsometry. Finally, the response of mesenchymal stem cells to adhesion and culture at corresponding interfaces is investigated via immunostaining and confocal microscopy.

Influence of interfacial compatibilization caused by epoxidized cardanol on the toughness of poly (lactic acid)/flax fiber blends

Poly (lactic acid) (PLA)/flax fiber/cardanol (or epoxidized cardanol) blends were prepared by mould injection. Epoxidized cardanol was effective on toughening PLA/flax fiber blends. The maximum notched Izod impact strength of PLA/flax fiber/epoxidized cardanol (80/10/10) blend reached 10.42 ± 0.61 kJ/m2 i.e. two fold of PLA/flax fiber (90/10) blend (5.18 ± 0.23 kJ/m2). Also, the elongation at break of PLA/flax fiber/epoxidized cardanol (85/5/10) blend was promoted to 43.76 ± 8.58 %, which was over four fold of PLA/flax fiber (95/5) blend (9.94 ± 1.65 %). The improved interfacial compatibility caused by epoxidized cardanol was presumed to be responsible for the superior toughness.

Bioinspired Strong, Tough, and Biodegradable Poly(Vinyl Alcohol) and its Applications as Substrates for Humidity Sensors

AbstractBiodegradable polymeric materials with high strength and outstanding toughness are necessary for real‐world applications in the fields of electronics, electrics, and packaging. Unfortunately, such performance portfolios in polymers remain challenging to achieve due to their different governing mechanisms. Inspired by the hydrogen‐bond (H‐bond) cross‐linking structure of spider silk, herein, strong and tough poly(vinyl alcohol) (PVA) composites with β‐cyclodextrin as a cross‐linker are developed. Benefiting from the H‐bond cross‐linking effect, the addition of 1.0 wt% of β‐cyclodextrin enables PVA to achieve a high tensile strength of 136.5 MPa, and a high elastic modulus of 3.0 GPa, in combination with a good toughness of 82.1 MJ m−3. In addition, the presence of β‐cyclodextrin improves the biodegradability of PVA composite by decreasing its crystalline size. Furthermore, PVA/β‐cyclodextrin composite combined with MXene has great potential as a sensor material for humidity and strain detection. This proof‐of‐concept opens numerous opportunities to create strong, tough, and biodegradable polymers for packing and sensing applications.