JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2024
·Vol. 149
·期 10
·4655-4670
·
IF 3
Qu Haowen,Bai Mingqi,Dang Jing,Shu Chi-Min,Yu Yanan,Li Kai,Deng Zijian,Li Bing,Liu Yi
Methylene diphenyl diisocyanate (MDI) serves as a primary component of polyurethane in various applications, including household appliances, architectural structures, automobiles, and adhesives. A recent MDI plant explosion in China highlighted the importance of studying MDI’s thermal stability and parameters to prevent accidental thermal decomposition. In this study, an extensive array of analytical techniques, including differential scanning calorimetry, thermogravimetric analysis, and adiabatic accelerating calorimeter, was employed to determine the thermokinetic constants of MDI, providing a solid foundation for further in-depth investigations. The findings revealed that MDI containing water reacts at substantially lower temperatures, while pure MDI can release heat and gases in an adiabatic environment, posing a considerable explosion risk. The kinetic constant of MDI was calculated using the Flynn–Wall–Ozawa method, yielding apparent activation energy values ranging from 51.78 to 96.70 kJ mol −1 across a conversion degree range of 0.05–0.70. The Coats–Redfern model pinpointed the kinetic reaction mechanism as a two-stage chemical process based on the apparent activation energy. Molecular optimization, following the energy minimisation principle, was conducted using Gaussian 09 software, which led to the identification of the optimal pathway for generating carbodiimide and carbon dioxide. This investigation offers valuable insights for the effective management of MDI during production, transportation, and storage, contributing to improve loss prevention practices in the industry.
研究领域:
化学工程
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材料科学
·
安全工程
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DOI
高影响因子
Nanomaterials
·
2022
·Vol. 12
·期 8
·1267
·
IF 5.719
Gang Lu,Changgeng Shuai,Yinsong Liu,Xue Yang,Xiaoyang Hu
To adapt to the complex application of polyurethane bearings, it is feasible to improve the tribological performance of single polyurethane-based friction materials through the synergistic effect produced by multi-component-lubricating fillers. In this context, rather than using tungsten disulfide (WS2), which has demonstrated excellent self-lubricating performance as a lubricating oil additive, this paper proposes that WS2and single-walled carbon nanotubes (SWNTs) can be designed for addition into a polyether 4,4′-diphenylmethane diisocyanate (MDI) polyurethane matrix as self-lubricating fillers so as to explore the synergistic effect of micro- and nano-lubricating fillers on the tribological performance of polyurethane matrix materials. Through a series of characterizations and tests, it was found that the dispersion of two-component-lubricating additives in a polyurethane matrix is improved when the ratio of WS2to SWNTs is roughly 2:1. In this case, the tribological performance of polyurethane matrix composites is more satisfactory than at other ratios. In addition, compared with the blank sample, the tribological performance of the synergistically modified polyurethane composites under dry friction is more significantly improved with the increase in contact load, while there is no significant improvement under water lubrication. Aside from contributing to the idea of exploring the synergistic effect of WS2and other micro or nanofillers, this method also opens up the possibility of practically applying WS2in the field of friction.Keywords:polyurethane elastomer;WS2;SWNTs;synergistic effect;tribological performance
研究领域:
材料科学
·
摩擦学
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产品关联
DOI
PubMed
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2024
·
IF 7.4
Mingen Fei,Chenhui Luo,Xiaoyan Zheng,Tengfei Fu,Kunqi Ling,Han Chen,Wendi Liu,Renhui Qiu
Pervious concrete has a unique open-skeleton structure and high permeability, which effectively control water runoff, mitigate urban heat island effects , and reduce traffic noise in urban constructions. However, low strength , easy granulation, and poor durability often limit its application in pavement engineering . As a polymer binder , vinyl ester (VE) resin has high strength, wear resistance, durability, and corrosion resistance , which can remedy the shortage of pervious concrete. In this work, by optimizing the aggregate gradation and curing temperature, high-performance pervious concrete using VE resin as binder was fabricated. To further improve the performance of VE binder, renewable acrylated epoxidized soybean oil (AESO) and diphenylmethane diisocyanate (MDI) were used to increase the crosslinking degree of the resin and the durability of pervious concrete. When using 15% AESO and 10% MDI based on the weight of VE, the pervious concrete achieved an enhanced flexural strength of up to 7.72 MPa. A significant improvement was achieved by incorporating 50 wt% solid wastes copper slag into the pervious concrete, the compressive strength and flexural strength reached 37.72 MPa and 7.53 MPa, respectively. The permeability coefficient of the permeable concrete was 2.64 mm/s, and the connected porosity was 11.33%, which are higher than the requirements of China national standard. The satisfactory durability of pervious concrete was also verified through freeze-thaw, abrasion, and aging tests. This work offers a viable strategy for cost-efficient and sustainable high-performance pervious concrete, providing insights into the utilization of renewable feedstocks and solid wastes in civil materials.
研究领域:
土木工程
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材料科学
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环境工程
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产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2024
·
IF 10.7
Cuihuan Li,Yuan He,Jiankang Zhang,Jiahui Mu,Junya Wang,Mengyao Cao,Haq Nawaz,Sheng Chen,Feng Xu
Many amines with high toxicity always cause a serious threat to the ecological environment and human health; thus, their detection is important. Herein, a dual-mode colorimetric and ratiometric fluorescent sensor based on cellulose for detecting amines has been constructed by a new strategy. This sensor is made of a “negative response” indicator (Lum-MDI-CA) and a “positive response” indicator (perylene tetracarboxylic acid, PTCA). Lum-MDI-CA was obtained by attaching luminol onto cellulose chains, which emitted blue fluorescence and was quenched upon contact with amines. A possible mechanism of fluorescence quenching phenomenon is proposed by the intramolecular charge transfer (ICT) of Lum-MDI-CA. Subsequently, by simply mixing Lum-MDI-CA with PTCA, a dual-mode fluorescence sensor was designed for visual detection and classification of amines. When adding ammonia (NH 3 ), morpholine (MOR), benzylamine (BNZ), diethylamine (DEA), and triethylamine (TEA), respectively, the dual-mode sensor showed visible different color changes under both UV light and daylight. In addition, owing to the excellent processibility and formability of cellulose acetate backbone, the prepared sensor can be easily processed into different material forms, including inks, coatings, films, and fibers, which still exhibit excellent fluorescence emission. Such sensors based on cellulose fluorescent materials are of great value in anti-counterfeiting and information encryption.
研究领域:
分析化学
·
材料科学
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环境科学
·
纳米技术
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产品关联
DOI
PubMed
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2015
·
IF 5.337
Kelin Peng,Changzhong Chen,Wanli Pan,Wenmin Liu,Zhiqiang Wang,Lanlan Zhu
Four β-cyclodextrin/4,4′-diphenylmethane diisocyanate/polyethylene glycol (β-CD/MDI/PEG) crosslinking copolymers with different crosslinking density were prepared and characterized as novel polymeric solid–solid phase change materials (SSPCMs) for thermal energy storage . In the SSPCMs, PEG acts as the phase change functional chain and β-cyclodextrin (β-CD) acts as the molecular framework. The results from wide-angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM) show that the synthesized SSPCMs have good crystallization properties and spherocrystal morphology with smaller size than that of PEG. According to the results of differential scanning calorimetry (DSC) and thermogravimetry (TG) curves, the SSPCMs possess high phase change enthalpies , good reusability , thermal reliability and stability. It is concluded that the crosslinking density of SSPCMs is a crucial factor significantly influenced the free movement and crystallization of PEG segments, and then affects phase transition properties of SSPCMs.
研究领域:
材料科学
·
高分子化学
·
热能存储
·
相变材料
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DOI
高影响因子
POLYMER BULLETIN
·
2022
·Vol. 80
·期 2
·1873-1891
·
IF 2.843
Shi Wenshuo,Wei Kun,Fan Yuzhe,Wang Xiaoqing,Shi Jiahao,Wang Sifan,Cheng Peng
Transition temperature is significant in determining applications of phase change materials. In this paper, PEG2000 and PEG4000 were used as soft segments and MDI and 3,3ʹ-Dichloro-4,4ʹ-diaminodiphenylmethane (MOCA) were used as hard segments. Several polyurethane solid–solid phase change materials (PUSSPCMs) were synthesized by adjusting the mass ratio of PEG4000 and PEG2000. Based on the differential scanning calorimeter test, this paper studied the relationship between the mass ratio of PEG2000 and the phase transition temperature. The influence mechanism of phase change temperature was revealed from molecular structure, crystallization properties, and surface morphology. Furthermore, PUSSPCMs were tested for leakage and the thermal stability. The results showed that the synthesized PUSSPCMs had no liquid leakage during the heating process. There was a good linear relationship between the mass ratio of PEG2000 and phase transition temperature. The thermal decomposition onset temperature was above 230 °C.
研究领域:
材料科学
·
化学工程
·
热能存储
✓ 已验证
产品关联
DOI
高影响因子
Desalination and Water Treatment
·
2015
·
IF 1.173
Qian Zhang,Chukwunonso Peter Okoli,Lingqing Wang,Tao Liang
Two kinds of cross-linked starch polymers were synthesized and used as adsorbent materials for the adsorption of o-nitrophenol (o-NP), p-nitrophenol (p-NP), 2,4-dinitrophenol (2,4-DNP) and 2-s-butyl-4,6-dinitrophenol (DNBP) from aqueous solutions. Results from adsorption experiments showed that the polymer 1 prepared by 4,4′-methylene-bis-phenyldiisocyanate (MDI) as cross-linking agent exhibited higher adsorption behaviors than that of the polymer 2 prepared by hexamethylene diisocyanate (HMDI). Equilibrium and thermodynamic of four nitrophenols on polymer 1 were further studied. Analyzed experimental data showed that the Freundlich model fitted the isotherm data better than the Langmuir model of the four nitrophenols onto polymer 1. The thermodynamics for the adsorption of the nitrophenols on polymer 1 were estimated in the range of 303–333 K. It has been found that the values of Gibbs free energy (ΔG) became more negative with decreasing temperature, which indicated that the adsorption process was more favorable at low temperature.
研究领域:
环境科学
·
化学工程
·
材料科学
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DOI
高影响因子
COMPOSITES SCIENCE AND TECHNOLOGY
·
2017
·
IF 4.873
Chen Wang,Yuan Xu,Shudong Sun,Changsheng Zhao
Herein, a new and facile approach by in situ cross-linking polymerizationcoupled with a post-functionalization procedure was developed to prepare functional PES composite membranes to improve its over-all performance as hemodialysis membrane. In our strategy, poly(acrylate acid-co-2-hydroxyethyl methacrylate) P(AA-co-HEMA) as a macromonomer, was firstly synthesized by free radical copolymerization , then blended in PES solution and in situ cross-linked polymerization via the reaction of the hydroxy group of HEMA and the isocyanate group of 4,4′-diphenylmethane diisocyanate (MDI) to prepare the carboxylic membranes. To further enhance the hemocompatibility , the carboxylic membranes were post-functionalized by grafting sulfonic acid groups onto the membrane surfaces via a “grafting from” method. The chemical compositions and surface morphologies of the prepared membranes were investigated by ATR-FTIR, XPS , SEM and AFM . After introducing the functional groups, the surface hydrophilicity of the membranes was significantly improved, demonstrated by the reduced water contact angles (WCAs) and enhanced permeability. The decreased protein adsorptions and higher flux recovery ratios (F RR s) revealed that the modified membranes showed improved protein antifouling property. The improvement of hemocompatibility was confirmed by the inhibited platelet adhesion, prolonged clotting times , and suppressed blood-related complement activation. Moreover, the post-functionalized membranes also showed good cytocompatibility. In general, the in situ cross-linking technique is a suitable route in the field of membrane modification for its facile and easy operation; and the post-functionalization operation could endow the membranes with efficiently improved properties.
研究领域:
材料科学
·
化学工程
·
生物医学工程
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产品关联
DOI
高影响因子
POLYMERS FOR ADVANCED TECHNOLOGIES
·
2021
·Vol. 32
·期 9
·3495-3504
·
IF 3.665
Kun Cong,Jiyu He,Rongjie Yang
TPU and flame-retardant TPU (FR-TPU) were prepared through a polyaddition reaction with polytetramethylene ether glycol (PTMEG) and 4,4′-methylene-bisphenyl-isocyanate (MDI) by reactive extruding. 1,4-Butanediol (BDO) and diethyl bis(2-hydroxyethyl) amino methyl phosphonate (DBAMP) were used as the chain extender in different ratios, respectively, to obtain TPU and flame-retardant TPU (FR-TPU)with adjusted molecular weight and mechanical properties. The resulting TPU and FR-TPU were characterized by FTIR, DSC, TGA, and NMR. A kinetic model based on the data from extrusion process was used to depict the polymerization of TPU. These reactions carried out without any solvent and the residual water showed that the polymerization with BDO could be achieved in 20 minutes, instead, that with DBAMP in 55 minutes while with a similar molecular weight. These results point out that Twin Screw Extrusion Reaction (TSER) is a suitable and convenient way to produce a variety of polymers.
研究领域:
材料科学
·
高分子化学
·
化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）