Influence of Interfacial Enantiomeric Grafting on Melt Rheology and Crystallization of Polylactide/Cellulose Nanocrystals Composites

Fang, Huagao; Yang, Kangjie; Xie, Qizheng; Chen, Xu; Wu, Shengli; Ding, Yunsheng

doi:10.1007/s10118-021-2635-7

Cited by 11 publications

(8 citation statements)

References 56 publications

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“…Infrared spectra of different samples were investigated on a Nicolet iS50 Fourier transform infrared spectroscopy with an attenuated total reflection assembly (ATR-FTIR, Thermo Scientific). The thermal properties of the vitrimer samples were measured on a Q2000 differential scanning calorimetry (DSC, TA Instruments) at the heating and cooling rate of 10 K/min to investigate the characteristic temperatures …”

Section: Methodsmentioning

confidence: 99%

“…The thermal properties of the vitrimer samples were measured on a Q2000 differential scanning calorimetry (DSC, TA Instruments) at the heating and cooling rate of 10 K/min to investigate the characteristic temperatures. 38 Rheological Characterization. Rheological measurements were performed on a TA DHR-1 rheometer (TA Instruments) using 8 mm plates and 0.5 mm thick samples of the fully cured vitrimers.…”

Section: Methodsmentioning

confidence: 99%

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Rheology of Smectic Liquid Crystalline Elastomers with Dynamic Covalent Bonds

Fang,

Zhang,

Zhao

et al. 2023

Macromolecules

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Liquid crystal elastomer networks (LCEs) have found a wide range of applications due to their unusual mechanical and optical properties. The introduction of dynamic covalent bonds with their possibilities for network renewal opens up further opportunities. Elastomeric vitrimer epoxies (EV, m-EV, and vLCE) were synthesized with increased liquid crystal mesogens (LCM), in which the rheological properties vary with the fraction of LCM in the backbone. Differing from EV and m-EV, the distinctive contributions arising from the smectic structure in the vLCE were manifested in several viscoelastic responses. The underlying mechanisms were discussed for the first time. The smectic-isotropic transition of LCM is expressed, and the residual partially ordered structure in vLCEs contributes to the relatively high storage modulus in heating scans and seems to be the cause of thermal memory effects in the closed-loop cooling and heating experiment. Time−temperature superposition (tTS) is applicable to the EV and m-EV. vLCE becomes�thermorheologically complex in the vicinity of the order−disorder transition temperature of LCM domains. The temperature dependence of the shift factors in tTS can be divided into two regions, showing Williams−Landel−Ferry (WLF)-type at lower temperatures and Arrhenius-type at higher temperatures. At lower temperatures, the flow activation energy (E WLF ) increases in the sequence of EV, m-EV, and vLCE, reflecting the increase in backbone stiffness and its control over chain mobility. The activation energy, associated with the release of the transient cross-link from a smectic layer, also exists in vLCE. Above the LC transition temperature, a stretched exponential Kohlrausch−Williams−Watts (KWW) function is introduced to quantitatively describe the network rearrangement kinetics in the stress relaxation process; a low exponent β indicates marked structural heterogeneity in vLCE. Increased LCM causes stress relaxation processes to slow down significantly in a highly elastic state. The activation energy (E a ) obtained from the Arrhenius dependence of characteristic relaxation times declines as the LCM content is increased. This could be attributed to the locally higher concentration of the ester group and catalyst in vLCE.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Rheology of Smectic Liquid Crystalline Elastomers with Dynamic Covalent Bonds

Fang,

Zhang,

Zhao

et al. 2023

Macromolecules

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“…The main feature of ROP in the grafting from the cellulose surface is the heterogeneous nature of this process. A typical procedure of such grafting involves the utilization of stannous (II) octoate as a catalyst (0.2-2.0 wt% with respect to the monomer) and performing the reaction in toluene at 80-130 • C for 18-24 h [67,199,202,205,208]. Chai et al reported the PLLA and PDLA synthesis in toluene at 170 • C for 8 h [201].…”

Section: Grafting "From"mentioning

confidence: 99%

Advances in Bio-Based and Biodegradable Polymeric Composites

2023

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“…The main feature of ROP in the grafting from the cellulose surface is the heterogeneous nature of this process. A typical procedure of such grafting involves the utilization of stannous (II) octoate as a catalyst (0.2–2.0 wt% with respect to the monomer) and performing the reaction in toluene at 80–130 °C for 18–24 h [ 67 , 199 , 202 , 205 , 208 ]. Chai et al reported the PLLA and PDLA synthesis in toluene at 170 °C for 8 h [ 201 ].…”

Section: Modification Of Cellulose Micro- and Nanomaterialsmentioning

confidence: 99%

“…Fang et al found that during the melt-crystallization process, CNC-g-PLLA provided better nucleation and less restriction to chain mobility than CNC-g-PDLA at undercooled conditions [ 205 ]. In particular, no melt crystallization was detected in neat PLLA during the cooling process, while the melting-crystallization temperatures were 92.3 and 97.8 °C for 5 and 15 wt% composites produced by injection molding, respectively.…”

Section: Aliphatic Polyesters/cellulose Compositesmentioning

confidence: 99%

Modification of Cellulose Micro- and Nanomaterials to Improve Properties of Aliphatic Polyesters/Cellulose Composites: A Review

Stepanova

Korzhikova-Vlakh

2022

Polymers

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Aliphatic polyesters/cellulose composites have attracted a lot attention due to the perspectives of their application in biomedicine and the production of disposable materials, food packaging, etc. Both aliphatic polyesters and cellulose are biocompatible and biodegradable polymers, which makes them highly promising for the production of “green” composite materials. However, the main challenge in obtaining composites with favorable properties is the poor compatibility of these polymers. Unlike cellulose, which is very hydrophilic, aliphatic polyesters exhibit strong hydrophobic properties. In recent times, the modification of cellulose micro- and nanomaterials is widely considered as a tool to enhance interfacial biocompatibility with aliphatic polyesters and, consequently, improve the properties of composites. This review summarizes the main types and properties of cellulose micro- and nanomaterials as well as aliphatic polyesters used to produce composites with cellulose. In addition, the methods for noncovalent and covalent modification of cellulose materials with small molecules, polymers and nanoparticles have been comprehensively overviewed and discussed. Composite fabrication techniques, as well as the effect of cellulose modification on the mechanical and thermal properties, rate of degradation, and biological compatibility have been also analyzed.

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Influence of Interfacial Enantiomeric Grafting on Melt Rheology and Crystallization of Polylactide/Cellulose Nanocrystals Composites

Cited by 11 publications

References 56 publications

Rheology of Smectic Liquid Crystalline Elastomers with Dynamic Covalent Bonds

Rheology of Smectic Liquid Crystalline Elastomers with Dynamic Covalent Bonds

Advances in Bio-Based and Biodegradable Polymeric Composites

Modification of Cellulose Micro- and Nanomaterials to Improve Properties of Aliphatic Polyesters/Cellulose Composites: A Review

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