CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2015
·
IF 1.098
Zhijuan Sun,Xiao Wang,Fei Guo,Chunyue Jiang,Qinmin Pan
Bio-sourced nylon 69, one of promising engineering plastics, has a great potential in developing sustainable technology and various commercial applications. Isothermal and nonisothermal crystallization kinetics of nylon 69 is a base to optimize the process conditions and establish the structure–property correlations for nylon 69, and it is also highly beneficial for successful applications of nylon products in industry. Isothermal and nonisothermal crystallization kinetics has been investigated by differential scanning calorimetry for nylon 69, bio-sourced even–odd nylon. The isothermal crystallization kinetics has been analyzed by the Avrami equation, the calculated Avrami exponent at various crystallization temperatures falls into the range of 2.28 and 2.86. In addition, the Avrami equation modified by Jeziorny and the equation suggested by Mo have been adopted to study the nonisothermal crystallization. The activation energies for isothermal and nonisothermal crystallization have also been determined. The study demonstrates that the crystallization model of nylon 69 might be a two-dimensional (circular) growth at both isothermal and nonisothermal crystallization conditions. Furthermore, the value of the crystallization rate parameter ( K ) decreases significantly but the crystallization half-time ( t 1/2 ) increases with the increase of the isothermal crystallization temperature. To nonisothermal crystallization, the crystallization rate increases as the cooling rate increases according to the analysis of Jeziorny's theory. The results of Mo's theory suggest that a faster cooling rate is required to reach a higher relative degree of crystallinity in a unit of time, and crystallization rate decreases when the relative degree of crystallinity increases at nonisothermal crystallization conditions.
研究领域:
材料科学
·
聚合物科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER SCIENCE SERIES A
·
2018
·Vol. 60
·期 3
·381-390
·
IF 0.729
Yang Dongyu,Yuan Chaosheng,Yang Kun,Shao Chunguang,Wang Yongqiang,Cheng Xuerui,Su Lei
Isothermal crystallization behavior of Pluronic F127 blended with and without an ionic liquid (IL) was investigated by in situ polarized optical microscopy (POM) and Fourier transform infrared spectroscopy (FTIR). For the pure F127, the POM and FTIR results showed that the spherulite size and crystallinity of F127 increased with the melting temperature increasing to 60, 80, and 135°C. This could be explained by the flexibility of the polymer chain at high melting temperatures. For the F127 blended with IL, the POM results showed that the morphology of F127 evolved from spherulite to dendritic segregation and fibrous crystal with the increasing IL content. FTIR results indicated that hydrogen bonds were formed between F127 and IL, and the intensity of the hydrogen bonds became strengthened gradually with increasing IL content. The effect of hydrogen bonds on the morphology evolution of F127/IL is discussed.
研究领域:
高分子科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2021
·Vol. 147
·期 3
·2239-2251
·
IF 4.626
Zhao Qian,Wang Bowen,Qin Chenyuan,Li Qiuxuan,Liu Chuntai,Shen Changyu,Wang Yaming
In this work, biodegradable poly(lactic acid) (PLA)/Ti 3 C 2 T x MXene nanocomposites were prepared through melt compounding. The roles of MXene in nonisothermal melt and cold crystallization of PLA were explored. The morphology, structure and crystallization behavior were studied using polarized optical microscopy, wide-angle X-ray diffraction and differential scanning calorimetry. For nonisothermal melt crystallization, the presence of MXene increases the crystallinity and shortens the half-crystallization time but does not change the crystallization peak temperature of PLA. For nonisothermal crystallization from the glassy state, the incorporation of MXene decreases the cold crystallization peak temperature and reduces the crystallinity marginally but does not affect the half-crystallization time of PLA. The crystallization kinetics analysis based on the Avrami equation shows that, for both the melt and cold crystallization, the crystallization mechanism is unchanged irrespective of the addition of MXene. The investigation would be useful for understanding the correlation between processing and properties of PLA/MXene nanocomposites.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2018
·Vol. 10
·期 11
·1284
·
IF 2.935
Bo Wang,Fu-hua Lin,Xiang-yang Li,Zhong-wei Zhang,Xiao-rong Xue,Si-xiao Liu,Xu-ran Ji,Qian Yu,Zheng-qiu Yuan,Xin-de Chen,Jun Luo
Bacterial cellulose (BC) is a new kind of cellulose with great potential in enhancing preparation of isotactic Polypropylene (iPP) composites, which have been found with excellent performance. However, the interface compatibility between BC and iPP is poor. In this study, iPP/BC composites were prepared by solution mixing. Esterification modified BC (CO) and Maleic anhydride grafted polypropylene (MAPP) added as a compatibilizer was both used to improve the interfacial compatibility of the iPP/BC composites. The rheology and isothermal crystallization behavior of the composites was tested and discussed. The result shows that the complex viscosity and storage modulus of the composite significantly increase in the rule iPP, iPP/BC2, iPP/CO2, and M-iPP/BC3, which indicates that the compatibility of the composite increases as this rule. According to the isothermal crystallization kinetics result, the crystal growth mode of iPP was not affected by the addition of BC and the interfacial compatibility. The spherulite growth rate of the iPP/BC composite increases with increasing crystallization temperature. Especially, the value decreases as the same rule with the complex viscosity and storage modulus of the composite at the same isothermal crystallization temperature. These results suggest that the interface compatibility of iPP/BC composites is greatly improved and the interface compatibility of the M-iPP/BC3 is better than the iPP/CO2.Keywords:Isotactic polypropylene;bacterial cellulose;rheology;isothermal crystallization
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 11
·6221-6227
·
IF 3.049
Nuo Ji,Guang Hu,Jianbo Li,Jie Ren
The influence of the addition of linear and four-arm poly(lactide) (PLA) stereocomplexes (scPLAs) on the non-isothermal and isothermal crystallization behavior of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) from the molten state was investigated. The linear PLAs and four-arm PLA with a similar chain length for each arm were synthesized by ring-opening polymerization. The linear and four-arm scPLAs were then prepared by solution blending and characterized by 1H-NMR, FTIR, and WAXD analysis. Various mass ratios of the scPLAs were subsequently added to PLLA and PDLA as nucleating agents and specimens were prepared by solution casting. The isothermal and non-isothermal crystallization behavior of the specimens was examined by differential scanning calorimetry and polarized optical microscopy. The SC crystallites effectively promoted the nucleation of the PLAs, thereby increasing the general crystallization rate of the matrix. A 10% content of stereocomplex nucleating agent increased the crystallization rate of PDLA and PLLA by more than 55% and 70%, respectively. Compared with the linear scPLA, the four-arm scPLA more strongly promoted crystallization at higher temperatures. This might be because the greater degree of branching and larger steric hindrance of the four-arm scPLA led to the formation of defective SC crystallites, which was more beneficial for adsorption of the matrix on the crystal surface and permitted the nucleation and growth at higher temperatures. These results demonstrate that scPLAs can potentially be used as nucleating agents to improve the performance and transparency of PLA films.
研究领域:
高分子科学
·
材料工程
·
化学合成
·
热分析
✓ 已验证
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2025
·
IF 6.3
Zhirong Liao,Yongzhe Fang,Fengshuo Zhang,Xinlu Nong,Huajing Zhang,Xiaoze Du,Chao Xu
Molten salts are promising phase change materials for high-temperature thermal energy storage. Mixing molten salts with nanoparticles is attracting much attention to enhance thermal performance. However, the solid-liquid phase transition mechanism of molten salt mixing with nanoparticles has not been revealed. Therefore, this study focuses on the non-isothermal crystallization behavior of solar salt (SS) and two solar salt-based nanofluids (Ag-SS and SiO 2 -SS). Firstly, SS, Ag-SS and SiO 2 -SS samples were prepared and characterized. Secondly, based on the DSC test results, the kinetic characteristics of the samples under different cooling rates were analyzed by the Jeziorny-modified Avrami equation and the combined model of Avrami and Ozawa. Then, the activation energy was calculated, and the phase diagram analysis was introduced to analyze the crystallization process. Finally, the topological evolution of crystals obtained from the visual experiments was discussed. The results showed that the latent heat of solar salt slightly reduced when mixing with 0.5 wt% SiO 2 nanoparticles but hardly changed with 0.5 wt% Ag nanoparticles. The crystallization of solar salt slowed down about 8 % after adding 0.5 wt% Ag nanoparticles but hardly changed with 0.5 wt% SiO 2 nanoparticles. The Jeziorny-modified Avrami equation can describe the first crystallization stage of the samples, while it was not for the second stage due to the eutectic transition. Adding Ag and SiO 2 nanoparticles would change the topological evolution of solid-liquid crystals. During the first crystallization phase, SS showed mainly epitaxial crystals with strong main stems, Ag-SS lots of acicular crystals, and SiO 2 -SS snowflake crystals with well-developed lateral branches.
研究领域:
材料科学
·
热物理学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF POLYMER ANALYSIS AND CHARACTERIZATION
·
2016
·
IF 1.515
Xu-Feng Xia,Jun-Hui Zhang,Jia-Ming Fan,Qian-Lu Jiang,Shi-Ai Xu
The non-isothermal crystallization kinetics of three functionalized polypropylenes (PPs; polypropylenes-g-acrylic acid [PP-g-AA], polypropylenes-g-glycidyl methacrylate [PP-g-GMA], polypropylenes-g-maleic anhydride [PP-g-MAH]) at different cooling rates were investigated by differential scanning calorimetry, using the Jeziorny method, Ozawa method, and Mo method. The result showed that Mo method can adequately describe the non-isothermal crystallization kinetics of pure PP and functionalized PPs, and at a given relative crystallinity, the crystallization rate obtained using Mo method followed an order of PP-g-AA > PP-g-GMA > PP > PP-g-MAH. The crystallization activation energy for these samples was calculated using Kissinger's method, which indicated that the introduction of monomers had a confinement effect on the motion of PP chains.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2019
·Vol. 139
·期 3
·1931-1939
·
IF 2.471
Qu Dezhi,Gao Hongwei,Wang Qiuxia,Bai Yongping,Li Ning
Crystallization kinetics are very important for polymeric materials due to the fact that they determine the final degree of crystallinity and the morphology of the final product after processing. The kinetic of non-isothermal crystallization of poly(butylene-co-isosorbide succinate) (PBIS) was investigated using differential scanning calorimetry. Ozawa, Jeziorny and Mo methods were used to describe the non-isothermal crystallization process of PBIS. Both the Ozawa constant and the Avrami constant were obtained by Ozawa method and Jeziorny method, respectively. The crystallization activation energy (∆ E ) for non-isothermal crystallization process of PBIS, analyze based on the differential isoconversional method of Friedman and Kissinger, was found to increase with the relative crystallinity.
研究领域:
材料科学
·
聚合物科学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2021
·Vol. 13
·期 21
·3815
·
IF 4.329
Wanxin Peng,Furui Sun,Yuke Liang,Jian Kang,Jinyao Chen,Wei Wang,Ya Cao,Ming Xiang
In this study, one of the commonly used MXene (Ti3C2Tx) and β nucleated isotactic polypropylene (β-iPP)/MXene composites of different compositions were fabricated. The effects of MXene on non-isothermal crystallization and polymorphic behavior of β-iPP/MXene composites were comparatively studied. The non-isothermal crystallization kinetics indicates that for all samples, the lower cooling rates promote composites to crystallize at higher temperatures. When MXene and β-Nucleating agent (β-NA) are added separately, the crystallization temperature of composites shifts towards higher temperatures at all cooling rates. When MXene and β-NA are added simultaneously, the composite shows different cooling rate dependence, and the effects of improving crystallization temperatures is more obvious under rapid cooling. The activation energy of four samples iPP, iPP/MXene, iPP/β-NA, and iPP/MXene/β-NA were −167.5, −185.5, −233.8, and −218.1 kJ/mol respectively, which agree with the variation tendency of crystallization temperatures. The polymorphic behavior analysis obtained from Differential Scanning calorimetry (DSC) is affected by two factors: the ability to form β-crystals and the thermal stability of β-crystals. Because β-crystals tend to recrystallize to α-crystals below a critical temperature, to eliminate the effect of β-α recrystallization, the melting curves at end temperatures Tend= 50 °C and Tend= 100 °C are comparatively studied. The results show that more thermally unstable β-crystals would participate in β-α recrystallization with higher cooling rates. Moreover, thermal stability of β-crystals is improved by adding MXene. To further verify these findings, samples of three different thermal conditions were synthesized and analyzed by DSC, X-Ray Diffraction (XRD), and Polarized Light Optical Microscopy (PLOM), and the results were consistent with the above findings. New understandings of synthesizing β-iPP/MXene composites with adjustable morphologies and polymorphic behavior were proposed.Keywords:istotactic polypropylene;MXene;nonisothermal crystallization behavior
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Omega
·
2021
·
IF 3.512
Wanxin Peng,Ran Hu,Weijiao Jiang,Jian Kang,Jingping Li,Ya Cao,Ming Xiang
MXenes, a family of two-dimensional transition-metal carbides/nitrides, have attracted great attention and shown promising application in polymer composites. In this study, a typical MXene Ti3C2Tx was prepared by selective etching. The structure and morphology of Ti3C2Tx were studied by X-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy, and the results proved that Ti3C2Tx was successively fabricated. Then, Ti3C2Tx/isotactic polypropylene composites with different Ti3C2Tx dosages were fabricated, and the nonisothermal crystallization kinetics and melting behavior of the composites were investigated. The results indicated that when a small amount of Ti3C2Tx was added, the crystallization parameters including the crystallization peak temperature and the crystallization rate increased, suggesting that crystallization was promoted. When the weight percentage of Ti3C2Tx exceeded 1%, the crystallization parameters showed a reverse trend, suggesting that crystallization was hindered. The activation energy of composites with 0, 0.25, 0.5, and 1 wt % Ti3C2Tx were calculated to be −164.5, −196.5, −193.8, and −147.95 kJ/mol, respectively, revealing that the crystallization of composites is concentration-dependent. The impact of Ti3C2Tx dosage on the crystalline structure of the composites was studied using XRD. The related mechanism was proposed.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Polymers
·
2023
·Vol. 15
·期 6
·1579
·
IF 5
Deling Li,Congcong Luo,Jun Zhou,Liming Dong,Ying Chen,Guangtian Liu,Shuyun Qiao
Corn starch was plasticized by glycerol suspension in a twin-screw extruder, in which the glycerol suspension was the pre-dispersion mixture of glycerol with nano-SiO2. Polylactide (PLA)/thermoplastic starch/SiO2composites were obtained through melt-blending of PLA with thermoplastic starch/SiO2in a twin-screw extruder. The nonisothermal crystallization behavior of PLA in the composites was investigated by differential scanning calorimetry. An interface of PLA with thermoplastic starch was proven to exist in the composites, and its interfacial bonding characteristics were analyzed. The interfacial binding energy stemming from PLA with thermoplastic starch exerts a significant influence on the segmental mobility of PLA at the interface. The segmental mobility of PLA is gradually improved by increasing interfacial binding energy, and consequently, the relative crystallinity on the interface exhibits progressive promotion. The Jeziorny model could well describe the primary crystallization of PLA in the composites. The extracted Avrami exponents based on the Jeziorny model indicate that the primary crystallization of PLA follows heterogeneous nucleation and three-dimensional growth. This study has revealed the intrinsic effect of the interfacial segmental mobility on the nonisothermal crystallization behavior of PLA in composites, which is of technological significance for its blow molding.Keywords:polylactide;composites;interfacial binding energy;nonisothermal crystallization kinetics
研究领域:
材料科学
·
高分子科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Polymers
·
2020
·Vol. 13
·期 1
·72
·
IF 3.426
Xin Tong,Zhao Wang,Mei-Ling Zhang,Xiao-Jun Wang,Gang Zhang,Sheng-Ru Long,Jie Yang
A series of novel thermoplastic elastomers based on (poly(decamethylene terephthalamide/decamethylene isophthalamide), PA10T/10I) and poly(ethylene glycol) (PEG) were synthesized via a facile one-pot, efficient and pollution-free method. The thermal analysis demonstrates that the melting points of the resultant elastomers were in the range of 217.1–233.9 °C, and their initial decomposition temperatures were in the range of 385.3–387.5 °C. That is higher than most commercial polyamide-based thermoplastic elastomers. The tensile strength of the resultant elastomers ranges from 21.9 to 41.1 MPa. According to the high-temperature bending test results, the resultant samples still maintain considerably better mechanical properties than commercial products such as Pebax®5533 (Arkema, Paris, France), and these novel thermoplastic elastomers could potentially be applied in high-temperature scenes. The non-isothermal crystallization kinetics of the resultant elastomers and PA10T/10I was investigated by means of Jeziorny and Mo’s methods. Both of them could successfully describe the crystallization behavior of the resultant elastomers. Additionally, the activation energy of non-isothermal crystallization was calculated by the Kissinger method and the Friedman equation. The results indicate that the crystallization rates follow the order of TPAE-2000 > TPAE-1500 > PA10T/10I > TPAE-1000. From the crystallization analysis, the crystallization kinetics and activation energies are deeply affected by the molecular weight of hard segment.Keywords:thermoplastic elastomer;non-isothermal crystallization kinetics;semi-aromatic polyamide
研究领域:
材料科学
·
聚合物化学
✓ 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）