Polymers
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2017
·Vol. 9
·期 8
·323
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IF 3.364
Xin-yu Song,Meng Wang,Yun-xuan Weng,Zhi-gang Huang
Bamboo flour (BF) was grafted onto lactide (LA) in the molten state using stannous octoate as a catalyst to form BF-g-LA. Then, polylactic acid (PLA) was blended with BF (PLA/BF, 85/15 wt %) to prepare PLA/BF/BF-g-LA composites using BF-g-LA as a compatibilizer. The grafting rate of BF was characterized using infrared testing and elemental analysis. To investigate the effect of BF-g-LA on the performance of PLA/BF/BF-g-LA composites, the phase morphology, thermal stability, and mechanical properties of the composites were characterized using scanning electron microscopy, thermogravimetric analysis, and universal material testing, respectively. The addition of BF-g-LA improved the interface compatibility between PLA and BF. When the BF-g-LA content was 2 phr, the tensile and impact strengths of PLA/BF/BF-g-LA composites were 55.3 MPa and 9.56 kJ/m2, representing 30% and 27% increases, respectively, relative to corresponding values for PLA/BF composites.Keywords:bamboo flour;lactide;graft;polylactic acid;compatibility
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
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2017
·Vol. 134
·期 17
·
IF 1.86
Yanmei Guo,Jun Shao,Haoqing Hou
Linear poly( d -lactide) (PDLA) with various molecular weights is synthesized and incorporated into commercial poly( l -lactide) (PLLA) with different optical purities. And then, the crystallization, mechanical and thermal properties of the PLLA and PLLA/PDLA cast films are investigated. In the PLLA and PDLA/PLLA specimens with lower optical purity, few homochiral crystallites (HC) form in all the specimens and only a small amount of PLA stereocomplex crystallites (SC) are observed in the blends. The elongation at break of all the specimens is extraordinary high, >300%. Dynamic mechanical analyses indicate that the destruction temperature increases at first, and then depresses as enlarging the molecular weight of PDLA in these blends. For the PLLA and PLLA/PDLA with higher optical purity, more content of HC develops in neat PLLA, and both SC and HC produce in the PLLA/PDLA specimens. However, the strains of neat specimens and binary blends are much lower than that of specimens with lower optical purity. The specimens with higher optical purity exhibit higher destruction temperatures and lower loss factors. The high content of crystals (SC and HC) would act as the physical cross-linking points and provide a key factor to impede the deformation of neat PLLA and binary blends during stretching, which should result in the fragile behavior of the PLLA and PLLA/PDLA blends with higher optical purity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44730.
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL RESEARCH
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2021
·
IF 0.782
Xiaolong Xu,Lijuan Liu
Lactic acid is an important platform compound used as raw material for the production of lactide and polylactic acid. However, its concentration and composition distribution are not as simple as those of common compounds. In this work, the mass concentration distribution of highly concentrated lactic acid is determined by back titration. The components of highly concentrated lactic acid, crude lactide, and polymer after the reaction are analyzed by HPLC. Different concentrations of lactic acid solution were prepared for the synthesis of lactide and its content in the product was determined by 1H NMR analysis. We found that lactide is more easily produced from high-concentration lactic acid solution with which the condensed water is easier to release. Hence, the removal of condensed water is crucial to the formation of lactide, although it is not directly formed by esterification of two molecules of lactic acid.
研究领域:
生物化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2025
·
IF 4
Liu Xue,Li Hang,Dai Jun-Xiang,Tian Guo-Qiang,Chen Si-Chong,Wu Gang,Wang Yu-Zhong
Poly(lactic acid) (PLA), a bio-based polymer, is considered to be a sustainable alternative to conventional petroleum-based plastics. However, owing to its widespread use and relatively slow degradation rate in water, PLA still poses potential environmental pollution risks after being discarded. The efficient chemical recycling of PLA represents an attractive approach to addressing both resource reuse and environmental pollution challenges caused by its waste. Hydrolysis is the predominant method of industrial recycling. However, because PLA is insoluble in water, efficient heterogeneous hydrolysis requires high-temperature and high-pressure conditions. In this study, an efficient homogenous hydrolysis method capable of simultaneously dissolving PLA and calcium hydroxide (Ca(OH) 2 ) was developed. Suitable solvents for this method were screened, and it was found that PLA hydrolysis using dioxane and 1,4,7,10,13-Pen-taoxacyclopentadecane as solvents achieved conversion rates of 93% and 90%, respectively, within 2 h at room temperature. Notably, the hydrolysis product, calcium lactate, precipitated as a solid from the solvent and therefore self-separated from the reaction solution. The solvent, acid/base conditions, water content, and depolymerization kinetics were investigated. Compared with previously reported hydrolysis methods, the enhanced efficiency observed in this study can be attributed to the concurrent solvation of PLA and Ca(OH) 2 , which maintains homogeneity throughout the reaction process. Additionally, this method facilitates closed-loop recycling of PLA and is compatible with the highly selective recovery of PLA from various types of PLA products.
研究领域:
材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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2012
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IF 2.947
Hui-xue Ren,Han-jie Ying,Ping-kai Ouyang,Ping Xu,Jing Liu
Efficient and pollution-free catalysts play an essential role in the ultimate biodegradation of products in the synthesis of biodegradable and recyclable poly( l -lactic acid) (PLLA). Therefore, macroporous resin was utilized as the solid acid for the first time, on which lactate that could be absorbed in vivo was composited to catalyze the synthesis of PLLA. It was discovered that macroporous resin Amberlyst-15 showed good catalytic activity in oligomerization and polymerization, and lactate showed different catalytic efficiencies due to the differences in ionic radius and ionic charge. Compared to the traditional catalysts of SnCl 2 ·2H 2 O/TSA, the composite catalyst can improve the quality, yield and optical purity of its product, which can also be recycled without any residual in products. PLLA with molar mass of about 110,000 g mol −1 was synthesized at the yield of 93%. The product exhibits pure color (white), and its optical purity and crystallinity are 98% and 55%, respectively. A possible catalytic mechanism was proposed. The resulting PLLA products were characterized by GPC, 1 H NMR, DSC, and polarimeter.
研究领域:
材料科学
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生物工程
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
BIOTECHNOLOGY AND BIOENGINEERING
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2022
·Vol. 119
·期 7
·1903-1915
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IF 4.395
Niling He,Jia Jia,Zhongyang Qiu,Chun Fang,Gunnar Lidén,Xiucai Liu,Jie Bao
Cyclic chiral lactide is the monomer chemical for polymerization of high molecular weight polylactic acid (PLA). The synthesis of cyclic l -lactide starts from poly-condensation of l -lactic acid to a low molecular weight prepolymer and then depolymerized to cyclic l -lactide. Lignocellulose biomass is the most promising carbohydrate feedstock for lactic acid production, but the synthesis of cyclic l -lactide from l -lactic acid produced from lignocellulose has so far not been successful. The major barriers are the impurities of residual sugars and inhibitors in the crude cellulosic l -lactic acid product. Here we show a successful cyclic l -lactide synthesis from cellulosic l -lactic acid by lignocellulose biorefining with complete inhibitor removal and coordinated sugars assimilation. The removal of inhibitors from lignocellulose pretreatment was accomplished by biodetoxification using a unique fungus Amorphotheca resinae ZN1. The nonglucose sugars were completely and simultaneously assimilated at the same rate with glucose by the engineered l -lactic acid bacterium Pediococcus acidilactici . The l -lactic acid production from wheat straw was comparable to that from corn starch with high optical pure (99.6%), high l -lactic acid titer (129.4 g/L), minor residual total sugars (~2.2 g/L), and inhibitors free. The cyclic l -lactide was successfully synthesized from the regularly purified l -lactic acid and verified by detailed characterizations. This study paves the technical foundation of carbon-neutral production of biodegradable PLA from lignocellulose biomass.
研究领域:
生物化学
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可再生资源与环境工程
✓ 已验证
DOI
高影响因子
POLYMER DEGRADATION AND STABILITY
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2024
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IF 6.3
Qiuyang Liu,Rulin Yang,Bingzhe Dong,Hongguang Sun,Guangqiang Xu,Qinggang Wang
The depolymerization of waste plastics into high-value products is a promising solution to address the plastic crisis. Among this field, catalytic activity and selectivity of depolymerization catalyst are of great concerns. Accordingly, in this work, a simple catalytic system was explored in detail to achieve the fast and selective chemical recycling of PLA into methyl lactate. Using commercially available M[bis(trimethylsilyl)amide] (MHMDS, M = Li, Na, K) as catalysts, the depolymerization of PLA was completed within a few minutes at room temperature. The selectivity and optical purity of the depolymerized product methyl lactate are greater than 99 %. The effect of conditions such as metal center, catalyst form, and solvent on depolymerization was investigated. Moreover, the gram-grade depolymerization, selective depolymerization of blended or mixed PLA plastic, and the recyclability of catalyst were further explored. This work accomplishes the path of highly selective and active depolymerization of PLA under mild conditions, thereby promoting sustainable development of PLA.
研究领域:
材料科学
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环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS COMMUNICATIONS
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2018
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IF 3.463
Marzieh Ghadamyari,Somboon Chaemchuen,Kui Zhou,Michiel Dusselier,Bert F. Sels,Bibimaryam Mousavi,Francis Verpoort
Poly (lactic acid) (PLA) is extensively used as an eco-friendly compound for many applications. The synthesis of stereo-pure lactide, specifically l , l -lactide which is the most desired isomer for the synthesis of high-quality PLA is very important. In this work, various materials including MOFs and simple bases have been applied as catalysts for the Lactide synthesis. Herein we report the one-step synthesis of l , l -lactide with high selectivity and yield (99%) in the absence of racemization by applying a cost-effective Cs 2 CO 3 catalyst. The novel described procedure is even expected to be very efficient for industrial applications.
研究领域:
材料科学
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化学工程
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2023
·Vol. 15
·期 2
·413
·
IF 5
Jialin Xu,Kuo Zhou,Linlin Qin,Zaiming Tan,Shijing Huang,Peigao Duan,Shimin Kang
The chemical recycling of end-of-life polylactic acid (PLA) plays roles in mitigating environmental pressure and developing circular economy. In this regard, one-pot tandem alcoholysis and hydrogenation of PLA was carried out to produce 1,2-propanediol, which is a bulk chemical in polymer chemistry. In more detail, the commercially available Raney Co was employed as the catalyst, and transformation was conducted in ethanol, which acted as nucleophilic reagent and solvent. Single-factor analysis and Box–Behnken design were used to optimize the reaction conditions. Under the optimized condition, three kinds of PLA materials were subjected to degradation. Additionally, 74.8 ± 5.5%, 76.5 ± 6.2%, and 71.4 ± 5.7% of 1,2-propanediol was yielded from PLA powder, particle, and straws, respectively, which provided a recycle protocol to convert polylactic acid waste into value-added chemicals.Keywords:polylactic acid;alcoholysis;hydrogenation;1,2-propanediol;PLA straws
研究领域:
化学工程
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
POLYMER DEGRADATION AND STABILITY
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2018
·
IF 3.193
Lidong Feng,Songyang Feng,Xinchao Bian,Gao Li,Xuesi Chen
In order to obtain the mechanisms of the pyrolysis reaction that poly (lactic acid) (PLA) gives lactide in the presence of Sn, the four types of low molecular weight PLAs (L-PLA) with different end-groups were prepared, including HO-L-PLA-COOH, R-L-PLA-OH, R-L-PLA-COOH, and R-L-PLA-R, and depolymerized by thermogravimetry at different heating rates. As for the pyrolysis reactions of the L-PLAs, their activation energy ( E a ) were estimated by the several isoconversional model-free methods and their kinetic models were also explored by the Malek method. The random degradation behavior of L-PLAs was determined by the plots of ln { − ln [ 1 − ( 1 − w ) 0.5 ] } vs. 1/T for experimental data from TG for L-PLAs and model reactions. The experimental results showed that the E a values and the possible kinetic models for the pyrolysis reactions of the L-PLAs were different due to the different end-groups and thereof the mechanisms for the pyrolysis reactions of PLA that give lactide were proposed under the catalysis of Sn. The pyrolysis reactions of R-L-PLA-OH and R-L-PLA-R trend to be controlled by a single kinetic model. The pyrolysis reactions of HO-L-PLA-COOH and R-L-PLA-COOH are more complex and controlled by not less than two kinetic processes. The pyrolysis reaction of PLA selectively produces lactide through the unzipping and intramolecular transesterification reactions, including the backbiting reaction caused by the Sn-carboxylate and Sn-alkoxide chain ends, which are directly formed from the hydroxyl and carboxyl end-groups of PLA, and the lactide selective elimination at the random position of the polymeric backbone.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
Biology Direct
·
2025
·Vol. 20
·期 1
·1-15
·
IF 4.9
Wei Xiaoyong,Zou Long,Huang Yanqing,Qiu Chuan,Cheng Guang,Chen Ye,Rao Jun
Background Hepatocellular carcinoma (HCC) is among the deadliest cancers globally. Yes-Associated Protein (YAP), a Hippo pathway effector, crucially regulates cell proliferation and apoptosis. Recent research has implicated YAP’s role in HCC progression, but the mechanisms are unclear. This study aims to clarify YAP’s function in HCC, emphasizing its regulation of key pathways and targets. Results Gene knockout and overexpression models were established in nude mice and cell lines of HCC cells to investigate YAP’s impact on tumorigenesis. Additionally, functional assays and molecular biology techniques were employed to identify YAP’s regulatory networks. The study demonstrates that LDHA-regulated lactate production promotes YAP activation and malignant phenotypes in HCC. Overexpression of LDHA in HepG2 and Huh7 cells increased lactate levels and activated the YAP pathway, enhancing cell proliferation, migration, and invasion. Lactate treatment also promoted these malignant phenotypes by inhibiting YAP phosphorylation at Ser127. In a xenograft model, lactate accelerated tumor growth through YAP activation. YAP lactylation at K102 antagonized its Ser127 phosphorylation, further promoting malignant progression. Conclusions This study highlights the significance of YAP in HCC pathogenesis, providing insights into potential therapeutic targets for HCC management. Graphical
研究领域:
肿瘤学
·
分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS A-GENERAL
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2024
·
IF 4.7
Yingdan Ye,Han Wang,Yibin Zhang,Huaiyuan Zhao,Weichen Du,Ping Chen,Zhaoyin Hou
Chemical upcycling of end-of-life plastics is an economically and environmentally feasible way to tackle plastics crisis. Among them, methanol alcoholysis of polylactic acid (PLA) is a promising approach, which can produce methyl lactate (MLA) that can be further converted to lactide to achieve a sustainable development. In this work, a series of WO x /ZrP catalysts with WO x active sites in low coverage and high surface area were synthesized via anchoring WO x species on the surface of zirconium phosphate (ZrP). Characterizations indicated that the strong interaction between WO x and ZrP promoted the formation of WO x active sites in low coverage. In particular, 10 %WO x /ZrP catalyst was highly active and stable for the alcoholysis of PLA plastics under mild conditions due to the abundant WO x active sites and strong acidity. The yield of MLA over 10 %WO x /ZrP catalyst reached 94.5 % within 4 h at 160 °C, which was superior to the performance of traditional solid acids ( α -ZrP, HZSM-5, H β and Amberlyst-45). In addition, 10 %WO x /ZrP was versatile for the alcoholysis of discarded PLA-based products and could be recycled at least five times. The prominent performance of 10 %WO x /ZrP catalyst and the possible reaction mechanism were discussed.
研究领域:
化学工程
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）