FERROELECTRICS
·
2018
·
IF 0.728
Yuguo Zhuo,Jun Liu,Qingshan Li
Nano-TiO2/MDI-50 based waterborne polyurethane composites were prepared with MDI-50, polypropylene glycol (PPG) and nano-TiO2 as main materials. Nano-TiO2 was modified using r-aminopropyltriethoxysilane (KH550) as modifier in order to improve the dispersion of nano-TiO2 in WPU. The composites morphologies and physical states were investigated using scanning electron microscopy (SEM), thermogravimetry analysis (TG), fourier transform infrared (FTIR) spectroscopy and UV-visible (UV-Vis) spectroscopy. Scanning electron microscopy observations revealed that modified nano-TiO2 has good dispersibility. Results from FTIR and TG suggested that the modified nano-TiO2 had been successfully introduced to the polyurethane molecular chain and the thermal decomposition temperature of nano-TiO2/MDI-50 based waterborne polyurethane composites doubled under the same thermal weight loss. Results from UV-Vis suggested that when 2% of modified nano-TiO2 was added, maximum absorbance of composites were significantly improved and was twice higher than that of pure waterborne polyurethane.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
POLYMER BULLETIN
·
2016
·Vol. 74
·期 6
·2099-2116
·
IF 1.371
Wu Lu,Guo Jingfeng,Zhao Shu
A series of flame-retardant waterborne polyurethanes were synthesized with 4,4′-diphenylmethane diisocyanate and polyethylene glycol600 (PEG600) and modified with different level of diethylbis(2-hydroxyethyl)aminomethylphosphonate (fyrol-6); besides, 1,1,1-Tris(hydroxymethyl)propane was introduced as chain extender and crosslinking agent. The structures of these waterborne polyurethanes were confirmed by Fourier transform-infrared spectroscopy. Thermal degradation properties and flame retardancy were investigated by thermal gravimetric analysis (TGA), limiting oxygen index (LOI), and vertical burning test (UL-94). Wettability and mechanical property of film were measured with contact angle analyzer and universal mechanical machine, respectively. The results showed that when the mass of fyrol-6 was 12.0 % and the TMP was 1.7 %, an LOI value of 28.1 % and a UL-94V-2 rating could be achieved. Besides, the mechanical properties, including tensile strength, 100 % modulus and impact strength, are also relatively good. Simultaneously, the TGA analysis indicated that the incorporation of fyrol-6 enhanced the carbon residue from 8.9 to 19.9 %.
研究领域:
材料科学
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高分子化学
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产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
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2015
·Vol. 132
·期 48
·
IF 1.768
Fei Zhao,Han-Xiong Huang,Shui-Dong Zhang
This work focuses on largely toughening poly(lactic acid)/thermoplastic polyurethane (PLA/TPU) blend with lower content (20 wt %) of TPU using appropriate contents of 4,4-methylene diphenyl diisocyanate (MDI) via simple melt blending. Both scanning electron micrographs and differential scanning calorimetry curves suggest little change of the compatibility between the PLA and TPU phases by adding the MDI. Dynamic rheological test demonstrates that a reaction occurs between the TPU phase and MDI during melt blending. Combining the rheological behaviors and gel contents of the blends, it can be speculated that adding the MDI extends the TPU chains and forms branched and crosslinked structure in the TPU chains sequentially. Toughening mechanism is analyzed and different impact strengths for the blends with different MDI contents are explained based on combined effects of the decreased crystallinities for the PLA matrix and the extended, branched and crosslinked structure in the TPU chains. A 0.8 wt % MDI content is optimal in terms of the impact strength (100.6 kJ/m 2 ) and the elongation at break (392.4%). The former is about 1.9 and 32.5 times of that for the blend without MDI and the PLA, respectively. Moreover, the MDI results in some increase in the tensile strength of the blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42511.
研究领域:
材料科学
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高分子化学
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产品关联
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2025
·
IF 8
Wenxiu Jiao,Jiaxing Zhang,Zhiyong Zhang,Aimin Sha,Meng Jia
Adding phase change materials (PCMs) to asphalt pavements can effectively reduce temperature sensitivity and delay snow and ice accumulation. This study aims to develop solid-solid phase change materials (SSPCMs) for asphalt pavements, with a focus on winter road de-icing. First, the suitability of polyethylene glycol (PEG) and polytetramethylene ether glycol (PTMEG) with varying molecular weights as soft segments was systematically evaluated based on phase change performance, thermal stability, phase change cycling stability, and specific heat capacity. SSPCMs were synthesized using a two-step solution polymerization method, with successful synthesis confirmed by FTIR analysis. The influence of different soft-to-hard segment ratios on phase change performance was also examined. PTMEG2000 exhibited excellent performance, with an exothermic phase change temperature range from 8.5°C to -1.2°C and an enthalpy of 94.3 J/g. Its thermal decomposition onset temperature was 266.05°C, and its performance remained stable after 20 thermal cycles. The incorporation of hard segments led to a reduction in both phase change enthalpy and the initial phase change temperature. At a molar ratio of 4,4′-diphenylmethane diisocyanate (MDI) to PTMEG2000 of 2.4:1, the phase change temperature range was 4.1°C to -5.1°C, with an enthalpy of 37.1 J/g, demonstrating great potential as a de-icing material for roads in cold climates.
研究领域:
材料科学
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土木工程
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DOI
高影响因子
HIGH PERFORMANCE POLYMERS
·
2020
·
IF 1.568
Yi Wang,Mengyao Huang,Yi Lei
Polyimides are usually synthesized over a long period of time, and the process is complex. In order to shorten the synthesis time and simplify the process, we developed an improved synthesis method, namely, microwave-assisted polycondensation. The 3,3′-4,4′-benzophenone tetracarboxylic dianhydride (BTDA)–2,4-tolylene diisocyanate (TDI)/1,1′-methylenebis(4-isocyanatobenzene) (MDI) ternary copolyimides prepared in this work have been synthesized using microwave heating at rather short reaction times (15 min), without the need for either the once-off addition of TDI/MDI or the drop-wise addition of that mixture. The structure of the desired ternary copolyimide was confirmed by proton nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. Its glass-transition temperature is above 400°C, and the temperature for 5% thermal loss under nitrogen atmosphere is 508.8°C. The tensile strength is 141 MPa, which shows that the microwave-assisted copolyimide has excellent heat resistance and mechanical properties.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 9
·4610-4623
·
IF 2.936
Hongwei Pan,Zonglin Li,Jia Yang,Xin Li,Xue Ai,Yanping Hao,Huiliang Zhang,Lisong Dong
In this work, poly(lactic acid) and poly(butylene adipate-co-terephthalate) (PLA/PBAT 50/50) were melt-blended in the presence of 4,4′-methylene diphenyl diisocyanate (MDI) which acted as a reactive chain extender. The mechanical properties, phase morphology, thermal behavior and crystalline structure of the blends were investigated. Fourier transform infrared measurements revealed that some remarkable chemical interaction had taken place between the two polymers and MDI. Upon increasing the content of MDI, the blends showed increased tensile strength and elongation at break. With the addition of 0–2 wt% MDI, the impact strength of PLA/PBAT-MDI blends increased from 7.0 kJ m−2 to 70.0 kJ m−2. A large shift towards each other in terms of the glass transition temperature was observed by DMA and DSC analysis. SEM micrographs showed not only a reduction in the PBAT phase size but also a significant increase in interfacial adhesion between the PLA and PBAT phases with increasing of MDI. Furthermore, the toughening mechanism of the oriented samples was confirmed by wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) images; it was possible for the smaller crystallites of blends to form during the course of chain extension.
研究领域:
材料科学
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高分子化学
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产品关联
DOI
PubMed
高影响因子
MATERIALS SCIENCE FORUM
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2016
·
IF 0
Yue Ting Li,Hui Qin Lian,Yan Ou Hu,Lei Zu,Xiu Guo Cui,Yang Liu,Yu Peng Liu,Ben Ze Wu
Liquid crystalline polyurethanes (LCPU) were prepared from 4,4’-methylenediphenyl diisocyanate (MDI), 1,6-hexanediol (HDO), 2,2-dimethylol propionic acid (DMPA) and polytetramethylene ether glycol (PTMG). The experiments synthesized three liquid crystalline polyurethane films with different soft/hard segment ratio. Chemical and structural characterization of the polyurethanes were investigated by Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, differential scanning calorimeter and polarized microscopy respectively. Swelling rate and shape memory property were tested. The results indicated that the polyurethane with 62% soft segment and large group of carboxyl displayed excellent swelling and shape memory properties, and the shape recovery rate reached 100%. It was found that the crystallinity, thermal stability decreased and the temperature flexibility, water absorption and shape recovery rate increased with the increase of polytetramethylene ether glycol.
研究领域:
材料科学
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高分子化学
·
智能材料
·
形状记忆聚合物
✓ 已验证
DOI
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2023
·
IF 8.2
Lidong Chen,Jin Wu,Gaojian Zhu,Chao Liu,Tingting Xu,Liulian Huang,Weibing Wu,Jiaqi Guo,Huining Xiao,Hongqi Dai,Chen Huang,Zhen Zhang,Huiyang Bian
A large number of polluting substances, including chlorinated organic substances that were highly stable and hazardous, has been emitted due to the rapidly developing chemical industry, which will affect the ecological environment. Nanocellulose aerogels are effective carriers for adsorption of oil substances and organic solvents , however, the extremely strong hydrophilicity and poor mechanical properties limited their widespread applications. In this study, TEMPO-oxidized cellulose nanofibrils was modified with 2, 4-toluene diisocyanate (TDI) and 4,4′-diphenylmethane diisocyanate (MDI) to prepare strong and hydrophobic aerogels for oil adsorption. The main purpose was to evaluate and compare the effects of two diisocyanates on various properties of modified aerogels. It was found that the modified aerogel had better hydrophobic properties, mechanical properties and adsorption properties. In particular, the modified aerogel with TDI as crosslinker showed a better performance, with a maximum chloroform adsorption capacity of 99.3 g/g, a maximum water contact angle of 131.3°, and a maximum compression stress of 36.3 kPa. This study provides further evidence of the potential of functional nanocellulose aerogel in addressing environmental pollution caused by industrial emissions.
研究领域:
材料科学
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环境科学
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产品关联
DOI
PubMed
高影响因子
EUROPEAN POLYMER JOURNAL
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2021
·
IF 4.598
Chengqiang Li,Fangping Chen,Bowen Lin,Chenhao Zhang,Changsheng Liu
The corn starch/Poly (butylene adipate-co-terephthalate) (PBAT) composites with high starch content and high mechanical strength were prepared by in-situ reaction with 4,4′-methylene diphenyl diisocyanate (MDI) as bifunctional crosslinker and polyurethane prepolymer (PUP) as starch modifier and physical compatibilizer. We studied the effects of different MDI contents on the mechanical properties, morphology, thermodynamics, rheology, water absorption and heat-sealing properties of starch/PBAT composites. The results showed that MDI was an effective reactive crosslinker, promoting the interfacial adhesion between modified starch and PBAT . The hydrophobicity, thermal stability, heat-sealing performance and mechanical properties of Starch/PBAT composites enhanced with the increased contents of MDI. The tensile strength and elongation at break of composites with 60% starch content reached 10.95 MPa and 461.23 %. The potent interfacial compatibility of starch/PBAT composites was mainly attributed to the chemical cross-linking of MDI and the physical compatibilization of PUP. Physical-chemical dual compatibilization in our study provided an effective strategy for preparing biomass-based polymers.
研究领域:
材料科学
·
生物基材料
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DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2017
·
IF 3.169
Xiong Xu,Jianying Yu,Canlin Zhang,Zhilong Cao,Yi Gu,Lihui Xue
This paper mainly investigates the effect of the reactive rejuvenator diphenyl methane diisocyanate (MDI) and 1,4-butanediol diglycidyl ether (BUDGE) on chemical structures of aged SBS and rejuvenated structures, rejuvenation mechanisms, physical and rheological properties of UV-aged SBS modified bitumen (SMB). Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) show the hydroxyl and carbonyl groups have formed on aged SBS, which indicates that the broken-chain structures of SBS have formed after UV radiation. Meanwhile, the disappeared hydroxyl groups and formed amide bond in FTIR spectrum of MDI rejuvenated SBS, and the associated hydroxyl groups and another appeared carbonyl groups in FTIR spectrum of BUDGE rejuvenated SBS indicate MDI and BUDGE can act as a “bridge” to connect the broken-chain SBS together at 150 °C. Moreover, the performance results show rejuvenation temperature and time have little impact on the physical properties of rejuvenated SMB whatever the rejuvenator is selected. With the increasing content of MDI, the softening point of rejuvenated SMB can be improved and the ductility at low temperature remains almost unchanged. However, the softening point of rejuvenated SMB decreases and the ductility increases as the rising content of BUDGE. Phase angle results indicate MDI can further increase the elasticity of aged SMB, and BUDGE can to some extent restore the viscosity characteristic. From the results of fatigue and rutting performance, 1% BUDGE weakens the fatigue limit temperature of aged SMB from 20.1 °C to 14.9 °C and 1% MDI increases the rutting limit temperature from 79.6 °C to at least 80 °C, which indicates BUDGE and MDI can respectively help improve the fatigue resistance and rutting resistance. Based on the analysis of FTIR spectra and the relative functional group indexes, the results show the increasing concentration of I NH CO in MDI rejuvenated SMB and I C O C in BUDGE rejuvenated SMB, indicating the chemical reaction between reactive rejuvenators and aged SMB can be occurred. The rejuvenation of aged SMB with MDI or BUDGE abides by the addition reaction mechanism or condensation reaction mechanism.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Case Studies in Construction Materials
·
2026
·
IF 6.6
Yitong Hou,Qiqi Zhan,Xinqiang Zhang,Bailin Shan,Liming Yang,Pan Liu,Yanan Cui
Epoxy asphalt is widely applied in steel bridge deck paving due to its high strength and thermal stability. However, the thermosetting epoxy resin becomes highly brittle after curing, resulting in insufficient toughness and poor low-temperature crack resistance. To address this issue, a novel high-toughness epoxy asphalt (HTEA) was developed by grafting polytetramethylene ether glycol-diphenylmethane diisocyanate (PTMG-MDI), serving as polyurethane flexible segments, onto epoxy resin and incorporating it into asphalt. The cured high-toughness epoxy resin (HTER) exhibited good thermal stability and mechanical properties, with a tensile strength of 4.05 MPa and an elongation at break of 143 %. HTEA showed slightly reduced tensile strength but significantly increased elongation at break. Rheological tests indicated that the retention time of HTEA reached up to 37 min. The storage modulus decreased in the low-temperature region, while the high-temperature creep compliance changes only slightly, indicating improved creep recovery performance. The fracture morphologies of HTER and HTEA exhibits ductile characteristics. The PTMG-MDI increases the density of cross-linking points in the three-dimensional network, thereby improving the low-temperature crack resistance of epoxy asphalt. When the HTER content is 40 % the glass transition temperature of HTEA is as low as −28.7℃, and the testing temperature is −24℃, the maximum creep modulus reaches 492 MPa, with a minimum creep rate of 0.242, indicating excellent low-temperature performance.
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产品关联
DOI
高影响因子
MOLECULES
·
2023
·Vol. 28
·期 2
·662
·
IF 4.6
Xiaoyan Ran,Ping Guo,Caifang Liu,Yulan Zhu,Cheng Liu,Bangjin Wang,Junhui Zhang,Shengming Xie,Liming Yuan
The chiral covalent-organic framework (CCOF) is a new kind of chiral porous material, which has been broadly applied in many fields owing to its high porosity, regular pores, and structural adjustability. However, conventional CCOF particles have the characteristics of irregular morphology and inhomogeneous particle size distribution, which lead to difficulties in fabricating chromatographic columns and high column backpressure when the pure CCOFs particles are directly used as the HPLC stationary phases. Herein, we used an in situ growth strategy to prepare core–shell composite by immobilizing MDI-β-CD-modified COF on the surface of SiO2-NH2. The synthesized MDI-β-CD-modified COF@SiO2was utilized as a novel chiral stationary phase (CSP) to explore its enantiomeric-separation performance in HPLC. The separation of racemates and positional isomers on MDI-β-CD-modified COF@SiO2-packed column (column A) utilizing n-hexane/isopropanol as the mobile phase was investigated. The results demonstrated that column A displayed remarkable separation ability for racemic compounds and positional isomers with good reproducibility and stability. By comparing the MDI-β-CD-modified COF@SiO2-packed column (column A) with commercial Chiralpak AD-H column and the previously reported β-CD-COF@SiO2-packed column (column B), the chiral recognition ability of column A can be complementary to that of Chiralpak AD-H column and column B. The relative standard deviations (RSDs) of the retention time and peak area for the separation of 1,2-bis(4-fluorophenyl)-2-hydroxyethanone were 0.28% and 0.79%, respectively. Hence, the synthesis of CCOFs@SiO2core–shell composites as the CSPs for chromatographic separation has significant research potential and application prospects.Keywords:chiral covalent-organic frameworks;core–shell composites;high-performance liquid chromatography;chiral separation
研究领域:
化学
·
分析化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）