查找使用阿拉丁产品的科研文献

Toughening PLA via Diisocyanate-Induced Dynamic Vulcanization of Carboxylated Oleic Acid: Role of Crosslinked Network Topology

Diisocyanate-induced dynamic vulcanization of difunctional fatty acids has emerged as a universal strategy to efficiently improve the impact resistance of polylactic acid (PLA). However, how the crosslinked network topology of the in situ formed polyamide elastomer (COPA) affects its toughening efficacy on PLA remains unknown. Here, we synthesized two carboxylated fatty acids with distinct molecular architectures (TCOA and NCOA) from technical-grade and high-purity oleic acids via UV-initiated thiol-ene click chemistry. These two diacids, along with tetradecanedioic acid (TA) without a dangling chain, were dynamically vulcanized with hexamethylene diisocyanate (HDI) to toughen PLA. By varying NCO/COOH molar ratios between HDI and TCOA, their effects on gel content, crosslinking density, phase morphology, and mechanical properties of resulting blends were systematically investigated. With increasing the ratio, both gel content and interfacial adhesion with PLA in the blends were enhanced, accompanied by the transformation of phase structure from “sea-island” morphology to a partially or fully co-continuous one. At a molar ratio of 1.8:1, the notched impact strength value of the blend reached 86.5 kJ/m2. By substituting TCOA with high-purity NCOA or TA, comparable gel content and interfacial compatibilization level, and co-continuous morphologies were achieved. Notably, NCOA yielded a PLA blend with a remarkably higher impact toughness (131.0 kJ/m2). The linear chain structure of TA led to a higher crosslinking density of the formed TAPA domains, which unfavorably suppressed their cavitation during impact fracture and thus resulted in an inferior impact strength (7.0 kJ/m2). These findings provide valuable insights into the toughening mechanism of PLA via dynamic vulcanization of monomers.

Study on the Mechanical Properties and Superhydrophilicity of Electrospun Coaxial Gel-PLA/PHBV Core–Sheath Nanofibers

Xinjiao Wang,Ping Liu,Xiaohong Chen,Honglei Zhou

The strength and hydrophilicity of nanofiber materials for tissue engineering have always been a significant challenge. This paper presents the design and preparation of PLA&Gel/PHBV core–sheath nanofibers that combine strength and super hydrophilicity using electrospinning technology. Compared to the original materials, the addition of gelatin simultaneously enhances both the strength and hydrophilicity of the materials, with the mechanical and hydrophilic properties of PLA&20 wt%Gel/PHBV nanofibers reaching optimal values of 7.45 MPa and 2.2°, respectively. The increase in strength is attributed to the entanglement effect caused by the gelatin molecular chains, which hinders the relative sliding of the molecular chains. The enhancement in hydrophilicity is due to the introduction of a large number of hydrophilic groups from Gel, improving the material's hydrophilicity. Additionally, the polar groups in gelatin and the emergence of a network pore structure significantly increase the material's water absorption rate. This work provides new insights into the design and preparation of nanofiber materials. Graphical A design and preparation method of electrospun fiber membranes with high strength and toughness and super-hydrophilicity.

Super-Toughed PLA Blown Film with Enhanced Gas Barrier Property Available for Packaging and Agricultural Applications

Yuanping Jiang,Cong Yan,Kai Wang,Dawei Shi,Zhengying Liu,Mingbo Yang

Polylactic acid (PLA) holds enormous potential as an alternative to the ubiquitous petroleum-based plastics to be used in packaging film and agricultural film. However, the poor viscoelastic behavior and its extremely low melt strength means it fails to meet the requirements in film blowing processing, which is the most efficient film processing method with the lowest costs. Also, the PLA’s brittleness and insufficient gas barrier properties also seriously limit PLA’s potential application as a common film material. Herein, special stereocomplex (SC) networks were introduced to improve the melt strength and film blowing stability of PLA; polyethylene glycol (PEG) was introduced to improve PLA’s toughness and gas barrier properties. Compared with neat poly(l-lactide) acid (PLLA), modified PLA is stable in the film blowing process and its film elongation at break increases more than 18 times and reaches over 250%, and its O2permeability coefficient decreased by 61%. The resulting film material also has good light transmittance, which has great potential for green packaging applications, such as disposable packaging and agricultural films.Keywords:PLA;biodegradable films;toughness;film blowing

Enhanced cold crystallization and dielectric polarization of PLA composites induced by P[MPEGMA-IL] and graphene

Pei Xu,Xiao Luo,Yiyang Zhou,Youwen Yang,Yunsheng Ding

To investigate the effect of modified graphene (Gra) by poly(methoxy poly(ethylene glycol) monomethacrylate-co-1-vinyl-3-ethylimidazolium bromide) (P[MPEGMA-IL]) on crystallization and dielectric behavior for poly(lactic acid) (PLA), the neat PLA and its composites were fabricated via solution blending and hot pressing. P[MPEGMA-IL] can improve the dispersibility of Gra in PLA matrix. The crystallization rate of PLA composites was increased with increasing the content of P[MPEGMA-IL] and Gra due to the plasticizing effect of P[MPEGMA-IL] and the nucleating effect of better-dispersed Gra. In the frequency spectra of PLA composites treated by cold crystallization process, α relaxation and interfacial polarization resulted in high values of dielectric permittivity. The incorporation of modified Gra into the matrix can accelerate interfacial polarization. The effect of modified Gra on charge carrier movement mechanism was resulted from the increase of the mobile charge carriers at the interphase and the dielectric strength of interfacial polarization.

Construction and Synthesis of High-Stability Biobased Oligomeric Lactate Plasticizer: Applicable to PVC and PLA Polymers

Zheming Zhang,Pingping Jiang,Phyu Thin Wai,Shan Feng,Minjia Lu,Pingbo Zhang,Yan Leng,Lingen Pan,Jie Pan

A novel green plasticizer, cyclohexyl ester-capped glutaric acid oligomeric lactate (CGOL) with many poly(lactic acid) (PLA) matrix repeating units, applicable for plasticizing both poly(vinyl chloride) (PVC) and PLA, was designed and developed through a two-step esterification reaction route. Due to the growing concerns about the environment and health, we used biobased raw materials to synthesize the biobased plasticizer with the hope of potentially replacing petroleum-based plasticizers that are already widely used. The molecular structure of CGOL was confirmed, and then CGOL was blended with PVC or PLA for performance testing. Compared with commercial plasticizers, it had better comprehensive plasticization performance, showing high thermal stability, mechanical stability, and migration stability in both PVC and PLA polymers, which could be demonstrated by thermogravimetric analysis, tensile tests, and migration resistance test results. Among all PVC blends containing 50 phr plasticizer, CGOL plasticized PVC films exhibited the highest elongation at break (736.3%) and initial degradation temperature (Ti, CGOL-50 = 273.5 °C), the lowest glass transition temperature (Tg = 24.8 °C), and minimal migration in various environments, better than that of commercial ATBC, DOTP, and DOP. As for PLA blends, CGOL plasticized PLA films outperformed PLA/ATBC films in terms of comprehensive performance. Overall, CGOL demonstrated potential as a novel green substitute plasticizer for preparing flexible products of PVC and PLA.

Synthesis of aluminum bis(hydroxy-phenyl-methyl)phosphinate and its synergistic flame retardant mechanism in PLA

Baoming Xu,Jingxue Yang,Xinhui Wang,Na Wang,Guorong Chen,Heng Zhang

In this paper, we report on the synthesis of a new aluminum bis(hydroxy-phenyl-methyl)phosphinate, AlBPi, under mild reaction conditions. The product structure was confirmed via characterization, and its thermal stability and flame retardant properties were assessed. To improve the flame retardant properties, we employed ammonium polyphosphate (APP) as a synergist with AlBPi. The PLA composite material containing 10% AlBPi and 5% APP achieved an LOI of 28.1% and a UL-94 rating of V-1. Cone calorimetry tests showed a significant reduction in PHRR, THR, PSPR, and TSP for the PLA/AlBPi/APP composite compared to the pure and PLA/AlBPi materials. SEM analysis revealed a continuous and dense char layer on the residual surface of the synergistic flame retardant sample. AlBPi and APP exhibited excellent synergistic flame retardant effects, with both releasing a large amount of PO·free radicals. APP was also able to release inert gas, exhibiting excellent flame retardant effects in the gas phase. Additionally, APP improved the charring performance of AlBPi and formed a compact char layer on the material surface, achieving good flame retardant effects in the condensed phase. Therefore, the AlBPi and APP synergistic flame retardant system can be considered a viable flame retardant additive for PLA. Highlights A novel flame retardant AlBPi was synthesized. AlBPi and APP demonstrate good synergistic flame retardant performance in PLA. AlBPi and APP play a flame retardant role in both gas and condensed phases.

The Preparation of Crystalline and Heat Resistance PLA in the Presence of Fully Biodegradable Macromolecular Nucleating Agent

Wang Jiang,Xin Meng,Weiguang Gong,Chenyang Li,Yichen Xu,Longjie Jiao,Pu Du,Zhong Xin

In this study, branched poly(lactic acid) (PLA) was synthesized through melt blending, which was blended with linear PLA (L-PLA) to enhance the crystallization. Nonisothermal and isothermal crystallization studies demonstrated that nucleated PLA exhibited a crystallization temperature and melt crystallinity of 119.0 °C and 48.0%, respectively, at the highest degree of entanglement of branched PLA (B-PLA). Following a simple annealing treatment, the Vicat softening temperature (VST) and heat deflection temperature (HDT) of nucleated PLA reached 157.2 and 94.3 °C, respectively. The presence of dipole interactions among molecular chain segments during the initial stages of nucleation was revealed via in situ infrared spectroscopy, which facilitated the adsorption of L-PLA onto B-PLA, thereby allowing branched segments to serve as nucleation sites for L-PLA. This comprehensive analysis elucidated the influence of B-PLA on the crystallization behavior of L-PLA and established a correlation between its degree of entanglement and nucleation efficacy. It could be concluded that nucleated PLA retains its biodegradability while demonstrating improved crystallization and heat resistance.

Enhanced thermal and mechanical properties of PLA/MoS2 nanocomposites synthesized via the in-situ ring-opening polymerization

Pengpeng Chen,Xiao Liang,Ying Xu,Yifeng Zhou,Wangyan Nie

In this work, MoS 2 nanosheets were employed to reinforce PLA. In order to promote the homogeneous dispersion of MoS 2 in PLA and form a strong interface between MoS 2 and PLA, the MoS 2 nanosheets were firstly modified by mercapto-ethylamine, and then functionalized with PLA chains through ring-opening polymerization of poly( l -lactide). The XRD, XPS, TGA and 1 H NMR characterizations confirmed the successful amino and PLA functionalization of MoS 2 nanosheets. The obtained MoS 2 -g-PLA nanosheets were then introduced to reinforce PLA. SEM images displayed that the MoS 2 -g-PLA nanosheets were dispersed in PLA matrix uniformly. TGA results showed that initial decomposition temperature was improved from 275.6 °C to 334.8 °C with 0.5 wt% of MoS 2 -g-PLA nanosheets. The storage modulus of PLA/MoS 2 -g-PLA-0.5 wt% in the glass state and rubber state were both greatly enhanced compared with neat PLA.

Laccase/TEMPO-mediated Graft Hydrophobization of Jute Fibers to Enhance the Mechanical Properties of Jute/PLA Composites

Dong Aixue,Teklu Kidanu Masho,Wang Weiming,Fan Xuerong,Wang Qiang,Ardanuy Mònica,Dong Zhen

In this work, the hydrophobization of lignocellulosic jute fibers was achieved via the laccase/TEMPO-mediated grafting of octadecylamine (OA) on their surface, with the aim to improve the interfacial compatibility with nonpolar polylactic acid (PLA) resins in fiber-reinforced composites. The modified jute fibers were analyzed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The characteristic vibrations of methylene groups and the increase in the surface C/O ratio of the jute fibers after the enzymatic treatment indicated that OA molecules were successfully grafted onto the jute fiber surface mediated by the laccase/TEMPO system. It was shown that the grafted jute fibers had increased surface hydrophobicity and reduced polarity with water contact angle of 124.2 °, diiodomethane contact angle of 94.1 ° and surface free energy of 11.44 mJ/m 2 , which were attributed to the presence of the OA nonpolar alkyl chains on their surface. The tensile, bending, and dynamic mechanical properties of the hydrophobized jute/PLA composites were enhanced, which suggested stronger interfacial adhesion between the jute fibers and the PLA matrix. The mechanical stability was investigated by water immersion measurements and it was found that the modified jute/PLA composites were better in this regards than the control jute/PLA composites. Therefore, this enzymatic hydrophobic modification could be used as an effective and eco-friendly method to produce natural lignocellulosic fiber-reinforced composites with excellent performance.

Furan-based renewable elastomers as effective tougheners for PLA: Enhanced mechanical properties and water vapor barrier properties

Xiaojun Ma,Hongji Wang,Hanyu Yao,Haohao Chang,Yuxuan Wei,Ziqing Wang,Yin Lv,Zhong Wei

There is a great need for versatile biomass additives sourced from renewable materials to enhance the performance of polylactic acid (PLA) composites. This study introduces a furan-based polyester elastomer called PNF-PBC that is designed to improve the mechanical and water vapor barrier characteristics of PLA. By incorporating PNF-PBC into PLA, the toughness of the PLA/PNF-PBC biocomposites was considerably enhanced through various intermolecular interactions. A 15 wt% PNF-PBC blend with PLA exhibited a 13.6-fold increase in elongation at break, while having a negligible impact on tensile strength. Furthermore, the water vapor barrier performance of PLA/PNF-PBC biocomposites was greatly boosted by a factor of 10 compared to pure PLA, making them highly suitable for food packaging materials. With its versatile properties, we anticipate that this bio-based PLA/PNF-PBC material will significantly expand the range of applications for PLA composites.

ZIF-71-programmed hydrophobic capillary gating in polylactic acid (PLA) composite aerogels for recyclable oil-water separation

Junyi Shi,Hongjuan Wang,Peng Liu,Dehai Yu,Dandan Ji

PLA-based composite aerogels with high oil selectivity, good reusability, and gravity-driven transport capability are promising materials for oily-water treatment and spill remediation. However, many high-performance oil/water separation aerogels still rely on non-degradable matrices or fluorinated surface modifiers. Herein, ZIF-71 nanoparticles were incorporated into a polylactic acid (PLA) aerogel to construct a hydrophobic capillary-gating network through solution blending, water-assisted thermally induced phase separation, liquid-nitrogen freezing, and freeze-drying. The chlorinated imidazolate framework contributed hydrophobic/oleophilic domains, polyhedral roughness, and textural porosity, while the PLA matrix provided a lightweight biodegradable skeleton. Compared with pristine PLA, the optimized PZ71–3 aerogel increased the water contact angle from 114° to 136°, tensile strength from 0.088 to 0.166 MPa, elongation at break from 10% to 25%, and total pore volume from 0.0066 to 0.0091 cm³ g⁻¹ , while showing a BJH average pore diameter of 10.8 nm. The aerogel resisted a water head of 14.5 cm, selectively captured both floating heptane and sinking CCl₄, achieved oil recovery efficiencies of 98.2–99.2% with gravity-driven oil fluxes of 5300–17,200 L m⁻² h⁻¹ , and retained stable oil sorption capacity and flux over 20 cycles. Comparative benchmarking shows that PZ71–3 offers a balanced performance profile among MOF/polymer and biodegradable-polymer aerogels. This work demonstrates ZIF-71-induced hydrophobic capillary gating as an effective fluorine-free strategy for recyclable PLA-based sorbents for oil/water separation.

Differentiated Stem Cell-Seeded Gelatin/PLA/P(3HB-co-4HB) Meniscal Scaffold with Biocompatibility and Mechanical Strength

Peng Li,Xiaoxin Cheng,Wuwei Li,Haiqing Yang,Yubi Jiang

Laceration is one of the most common meniscus injuries, which can cause knee joint dysfunction. The treatment of meniscus injuries remains one of the greatest challenges in orthopedics. In this study, a three-dimensional sponge-like Poly(lactic acid)/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (PLA/P(3HB-co-4HB)) scaffold with oriented microtubules was fabricated using an improved gradient thermal phase separation technique. The scaffold surface was modified by adsorbing gelatin. The surface-modified scaffolds and the unmodified scaffolds were divided into two groups. All preparation parameters were adjusted to meet tissue engineering requirements. The prepared scaffolds were tested for porosity, compression modulus, hydrophilicity, and degradability. Following scaffold preparation, induced differentiated rabbit bone marrow mesenchymal stem cells (BMSCs) were seeded to evaluate scaffold cytocompatibility. Cell proliferation was observed in the two scaffold groups, and cell viability was analyzed using CCK-8 assay, scanning electron microscopy (SEM), and confocal microscopy. Histological staining was performed to comparatively study cell synthetic function. Subsequently, tissue reconstruction and regeneration were evaluated following subcutaneous implantation of gelatin/PLA/P(3HB-co-4HB) scaffolds loaded with induced differentiated BMSCs in the dorsal regions of athymic nude mice. Results demonstrated that the gelatin/PLA/P(3HB-co-4HB) scaffold exhibited good cell compatibility, providing a suitable microenvironment for cell proliferation and differentiation. Furthermore, the scaffold supported the growth of seeded induced differentiated rabbit MSCs in vivo, maintaining meniscus cell phenotyping and function. The cell-laden scaffold has the potential to generate meniscus fibrocartilage.