POLYMER
·
2023
·
IF 4.6
Yong He,Kuiyong Dong,Yadong Guo,Gang Zhao,Shanshan Tang,Xueli Wang,Bomou Ma
Poly( L -lactide) (PLA) is the most important biobased polymer and is widely used in various fields. However, its application is still greatly limited by the distinct disadvantage such as poor thermal resistance . In this study, in order to improve the thermal properties, crosslinked PLA with high crystallinity (44 %) and high gel content (91 %) is prepared by the UV irradiation of its semicrystalline films by the loading of certain photoinitiators and curing agents . The structure and properties of the obtained films are systematically investigated with NMR, DSC , DMA , TG and WAXD . It is found that the crosslinking of the semicrystalline PLA film is more difficult than that of the amorphous in the absence of crosslinker. However, the combinations of 2phr photoinitiator such as 4,4′-dichloro benzophenone (DCB) and 2 phr crosslinker of 1,3,5-triallylisocyanurate (TAIC) can effectively trigger the crosslinking and high gel content up to 91 % can be achieved. Corresponding to the high density crosslinking, an increase of the glass transition temperature from 66.6 °C to 75.5 °C is observed for crystallized PLA, indicating an obvious improvement in thermal resistance. More interestingly, it is found that this crosslinked PLA with high crystallinity and high gel content still possesses high crystallizability.
研究领域:
材料科学
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高分子化学
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DOI
高影响因子
CHEMICAL PAPERS
·
2018
·Vol. 73
·期 2
·517-524
·
IF 0.963
Feng Yefeng,Deng Qihuang,Hu Jianbing,Peng Cheng,Wu Qin,Xu Zhichao
Abstract Ultraviolet (UV)-cured adhesives have attracted plenty of attention in the fields of health care and electronic components thanks to low energy loss and environment pollution. UV-cured adhesives bearing epoxy acrylate prepolymers have been extensively utilized, ascribed to low cost and high stability. However, the gel content of UV-cured adhesives has hardly been investigated in detail. The gel content has been found to strongly affect the mechanical properties and serving life of adhesives. We have found the strong composition dependence of adhesive performances of UV-cured adhesives before. To clarify the influencing factors of gel content in UV-cured adhesives containing epoxy acrylate prepolymers, in this work, a family of UV-cured adhesives with epoxy acrylate constituents have been elaborately designed and further fabricated. The influences of prepolymer kind, UV photoinitiator kind, UV photoinitiator concentration, reactive diluent concentration, feed style during preparing prepolymers and film thickness on gel weight fraction of cured adhesive films were deeply researched. This work might open the door to the large-scale preparation of promising high-performance UV-cured adhesives with a higher gel weight fraction based on regulating the formula. Graphical Abstract
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
Polymers
·
2021
·Vol. 13
·期 17
·2847
·
IF 4.329
Furong Wang,Chao Du,Junjun Chen,Lisheng Shi,Hailong Li
The study aimed at developing a new spectrophotometric method for determining the pectin content. Take commercial pectin as an example, and the method is based on the reaction of copper ions with pectin to produce copper pectate. The spectrophotometer was used to measure the remaining content of copper ions so as to calculate the pectin content. This method eliminated the weight step and avoided the error associated with it. Effects of reaction time, temperature, and pH on absorbance were also studied. Additionally, the accuracy of this method was verified. It indicated excellent repeatability and accuracy with the relative standard deviation of 2.09%. In addition, three different plant types were used to demonstrate the reliability of the method. To summarize, this method can be widely used for the determination of pectin content in many materials.Keywords:copper pectate;calcium pectate;ultraviolet and visible spectrophotometer
研究领域:
食品科学
·
分析化学
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DOI
PubMed
高影响因子
EUROPEAN POLYMER JOURNAL
·
2021
·
IF 4.598
Qiang Gui,Changou Pan,Pengwei Xie,Mingliang Pei,Peng Liu
Fluorination could efficiently improve the comprehensive performance of nitrile-butadiene rubber (NBR). However, severe gelation usually occurred in the radical graft polymerization onto the diene-based polymers. Here, a facile approach has been established for the facile fluorination of NBR without gelation via radical graft polymerization in presence of n -dodecylmercaptan (NDM) as chain transfer agent, with 2,2,3,4,4,4-hexafluorobutyl acrylate (F6) as the model fluorinating monomer. The gel content decreased with increasing the feeding ratio of NDM and reached 0 with a feeding ratio of NDM of 50 mol% of the initiator, with a fluorination degree of 0.50%. The graft polymerization mechanism was proposed with the 1 H NMR analysis. The proposed strategy is expected to provide a promising approach for the functionalization of diene-based polymers.
研究领域:
材料科学
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高分子化学
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DOI
高影响因子
Journal of Rubber Research
·
2022
·Vol. 24
·期 4
·555-562
·
IF 1.208
Chen Xu,Zhang Hui-Feng,Zhang Lu,Wei Yan-Chan,Hu Benxiang,Luo Ming-Chao,Liao Shuangquan
The changes in the structure, such as molecular weight, crosslinking density, and gel content, could influence the stability and the processing performance of natural rubber (NR) during storage. Previous works showed that temperature and humidity influence storage performances. Here, we found different coagulation methods could also affect storage behaviors of natural rubber, since coagulation methods could affect the content of non-rubber components. In this article, natural rubber latex was coagulated by three different coagulation methods. Under storage conditions, the content of some non-rubber components, namely the gel content, Mooney viscosity, Wallace initial plasticity ( \(P_{0}\) ), plasticity retention index (PRI), molecular weight, tensile strength, and crosslinking density of natural rubber were compared and analyzed. The results showed that properties (PRI, Mooney viscosity, and green strength) of NR were higher than that of NR-Salt and NR-Acid after storage; at the same time, PRI, Mooney viscosity, and green strength of NR-Salt were higher than that of NR-Acid after storage. Mooney viscosity and green strength of NR-Salt and NR-Acid showed a tendency for increase in the begin and then decrease. According to the changes before and after storage, we can choose suitable coagulation methods and rubber based on what we need.
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
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Chao Jiang,Yao Yang,Binbo Jiang,Jingyuan Sun,Zhengliang Huang,Zuwei Liao,Jingdai Wang,Yongrong Yang
Multiphase polypropylene is an important engineering plastic. Stickiness concerns in multiphase polypropylene particles with a high rubber content are well known, and they are not favorable to industrial production stability. However, there has been a scarcity of green and effective surface stickiness reduction techniques. In this work, a Damp mode was employed to construct multiple concentration zones at the particle scale, allowing the synthesis of polypropylene with a high rubber content, reduced particle surface stickiness, and dramatically increased copolymerization activity. The rubber content limit of the conventional gas-phase technique (designated as the Dry mode) was found to be approximately 30 wt % before the particles became sticky, whereas the rubber content limit of the Damp mode was found to be 45 wt %. More notably, early in the procedure, the gas-phase copolymerization activity was boosted by 86.7%. Furthermore, given the same rubber content, the impact strength and flexural modulus of the polymers synthesized in both modes and commercial resins were found to be essentially the same. Lastly, the polymer particles synthesized in Damp mode had a multizone structure with an EPR-rich core and an EPR-poor shell. This work establishes a new method for reducing the surface stickiness of multiphase polypropylene particles, paving the way for the manufacturing of high-performance polypropylene resins using ordinary polypropylene plants.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2025
·
IF 2.8
Yuhang Du,Yuanshan Cheng,Mingyao Zhang,Baijun Liu
Styrene–acrylonitrile copolymer (SAN) is widely used in various industries due to its excellent transparency, rigidity, and chemical resistance, but its brittle properties limit its utilization and development in niche areas. To improve the brittle properties of SAN resins for more applications, different PBA latexes were synthesized in this study by semicontinuous emulsion polymerization, and two key factors affecting the toughening effect of the resins, particle size and gel content of the poly butyl acrylate (PBA) rubber particles, were effectively and easily controlled. It was found that the crosslinker content and monomer dropping time could control the gel content of PBA latex, while the particle size of the latex was affected by the emulsifier distribution ratio and monomer dropping time. In addition, acrylate styrene acrylonitrile (ASA) resins were constructed by blending PBA-g-SAN graft copolymers with SAN resins, and impact strength tests were conducted to demonstrate the toughening effect on SAN resins. The experimental results show that the gel content can be as low as 73.03%, the particle size varies from 200 nm to 530 nm, and the maximum impact strength of ASA resin reaches 6.17 kJ/m 2 .
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
INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES
·
2020
·
IF 2.671
Yongxia Ren,Yunsheng Dong,Ruoning Yang,Youwei Yao
Ultraviolet (UV)/thermal dual-curable polyurethane acrylate (PUA) mixtures were prepared using a PUA oligomer , tripropylene glycol diacrylate (TPGDA), benzoyl peroxide (BPO), 2,4,6-trimethylbenzoyldiphenyl phosphine oxide (TPO), and cobalt isooctanoate. For purposes of comparison, a UV-curable PUA mixture was prepared by mixing the PUA oligomer, TPGDA, and TPO. When placed under a UV lamp (400 W, 50 mW/cm 2 ), the surface drying time of each curable mixture was approximately 2 s. The content of volatiles during UV curing (the intensity of the lamp was 100 mW/cm 2 ) was less than 0.3 wt%, and the content of potential volatiles (the test condition was heating at 110 °C for 1 h after UV curing) was below 1.0 wt%. Compared with the UV-cured sample, the UV/thermal dual-cured sample containing cobalt isooctanoate had more favorable properties, that is: (1) better acid and alkali resistance; and (2) better thermal stability and higher gel content. The temperature at 5 wt% weight loss ( T 5wt.% ) and the gel fraction of the UV-cured sample (the curing condition was 1 min of UV irradiation) were 269.4 °C and 94.6%, respectively. The T 5wt.% and the gel fraction of the UV/thermal dual-cured sample (cured at 100 °C for 10 min after 1 min of UV irradiation) were 318.2 °C and 99.8%, respectively. BPO and cobalt isooctanoate had little effect on the surface drying rate of the curable mixtures, and the performance of the cured samples was improved by thermal treatment following irradiation with UV. Considering the dyeing effect of BPO, this system provides a more practical approach to the complete curing of colored UV-curable resins.
研究领域:
材料科学
·
聚合物化学
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产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2025
·
IF 2.8
Yupan Li,Haozhi Wang,Gaorong Li,Wenfeng Peng,Hongtu Lin,Xiaoxue Liao,Lusheng Liao
This study investigated structural degradation differences in nonconstant viscosity rubber (TSR) and constant viscosity rubber (TSR CV) with two inherent molecular weight distributions (MWD) during mechanical mastication. The results demonstrated that compared with nonconstant viscosity treatment or unimodal MWD, constant viscosity treatment and bimodal MWD showed significantly retarded degradation of NR, as evidenced by molecular weight, Mooney viscosity, initial values, and macrogel content. Notably, the evolution of microgel ≥ 1 μm content exhibited divergent trends: For TSR, the microgel ≥ 1 μm content initially increased and then decreased with mastication time, whereas for TSR CV, it stabilized after partial degradation. The rheological analysis via Cole–Cole plots revealed that among all samples, the branched structure in the TSR from the Reyan73397 clone with bimodal MWD exhibited more pronounced degradation behavior, which was reflected by the variation of parameter h . These findings highlight the effects of MWD and constant viscosity treatment on the evolution of molecular chains, gel, and branching architecture during the mechanical masticating process of NR.
研究领域:
高分子科学
·
材料工程
·
化学加工
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产品关联
DOI
高影响因子
POLYMER
·
2020
·
IF 4.231
Xinke Zhong,Yihu Song,Qiang Zheng,Wanjie Wang
Gum vulcanizates exhibit Payne effect and weak strain overshooting behavior, which is usually forgot in rubber industry. Herein the Payne effect of butadiene rubber (BR) vulcanizates is investigated for clarifying the effect of crosslinking density and sol content mediated by using coagent in conjugation with dicumyl peroxide. Toluene extraction and paraffin swelling of the vulcanizates are performed for clarifying the contribution of sol fraction and chains entanglement. The results show that the Payne effect and weak strain overshooting of gum vulcanizates are closely related to effective crosslinking density rather than network defects. This work is helpful for understanding the nonlinear rheological responses of the gum vulcanizates with defective network structure.
研究领域:
材料科学
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高分子科学
·
流变学
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DOI
高影响因子
RSC Advances
·
2016
·Vol. 7
·期 1
·238-247
·
IF 3.289
Xuejuan Yang,Chunpeng Wang,Shouhai Li,Kun Huang,Mei Li,Wei Mao,Shan Cao,Jianling Xia
Two novel bio-based epoxy curing agents derived from myrcene (MMY) and castor oil (CMMY) were prepared, respectively. Their chemical structures were confirmed by Fourier transform infrared spectrometry (FTIR) and 1H nuclear magnetic resonance (1HNMR). The two curing agents were used to cure a commercial epoxy resin (E-51). The MMY-cured epoxy resin had very poor toughness while the CMMY-cured epoxy resin had low strength, so the two curing agents were mixed at different weight ratios to form new curing agents for the E-51 epoxy resin. The tensile strength, impact strength, dynamic mechanical properties, thermal stability, micro-morphology of fracture surfaces and gel content of the cured epoxies were all investigated. The curing behaviors of the cured epoxies were studied by differential scanning calorimetry (DSC). Results show that the elongation at break is increased and the tensile strength and glass transition temperature are decreased with increasing weight ratio of CMMY, while the impact strength is increased gradually. The initial degradation temperatures of all the cured epoxy resins were above 367 °C. The gel contents of the epoxy resins cured with the mixed curing agents were above 87%. The activation energies for the systems with MMY and CMMY were 75.90 and 67.69 kJ mol−1, respectively.
研究领域:
高分子化学
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材料科学
·
绿色化学
·
复合材料
·
热固性树脂
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生物基材料
·
聚合物改性
✓ 已验证
DOI
高影响因子
PLASMA CHEMISTRY AND PLASMA PROCESSING
·
2025
·
IF 2.5
Jiang Nan,Wang Yubo,Li Ju,Li Jie,Sheng Zunrong,Shang Kefeng,Lu Na,Wang Zhihong
Massive production and consumption of ground tire rubber (GTR) for transportation have led to significant waste rubber accumulation, posing a serious environmental threat. Rubber devulcanization technologies, as a promising strategy for rubber recycling, still face several challenges, including high consumption, pollution concerns. This study proposes an innovative method for rubber devulcanization using dielectric barrier discharge (DBD) plasma. Experimental results demonstrate a significant reduction in crosslink density, decreasing from 2.1 × 10 −4 mol/cm 3 to 0.8 × 10 −4 mol/cm 3 , after plasma treatment at a discharge voltage of 18 kV for 30 min. This reduction is accompanied by a decrease in gel content from 96.79 to 90.54%, indicating the effective cleavage of S-S and C-S bonds within GTR. Notably, after plasma treatment, the tensile strength and elongation at break of the regenerated rubber reached 10.2 MPa and 357.7%, respectively, meeting the standards for high-grade rubber. These mechanical properties meet the standards for high-grade rubber, rendering the devulcanized rubber suitable for reuse in industrial manufacturing processes. However, when the discharge voltage surpasses a critical level, the electron energy attains a magnitude sufficient to cause extensive structural damage to the rubber backbone of GTR. Consequently, this degradation results in a significant reduction in the molecular weight of the regenerated GTR, which ultimately leads to a decrease in both tensile strength and elongation at break. Based on a comprehensive analysis of experimental data and characterization results, a plausible mechanism for plasma-assisted devulcanization is proposed, highlighting the significant potential to enhance environmental sustainability and support circular economy initiatives.
研究领域:
环境工程
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高分子科学
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材料回收
·
等离子体技术
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）