POLYMER
·
2021
·
IF 4.43
Mingzhang Song,Wei Luo,Shuibin Feng,Wenjun Jiang,Yukai Ge,Tao Liu
Long-chain branched polypropylene (LCB-PP) was generated by a melt grafting reaction with trimethylolpropane triacrylate (TMPTA) as the grafting monomer and zinc dimethyldithiocarbamate (ZDMC) or styrene (St) as the co-monomers. High-temperature size exclusion chromatography (HT-SEC) was used to characterize the molecular mass , molecular mass distribution and branching degree of the modified PP. Subsequently, linear and nonlinear viscoelasticity data were obtained by a small amplitude oscillatory shear (SAOS) test and uniaxial extensional viscosity measurement. The pressure balanced bubble-growth (PBB) model was used to calculate the critical coalescence radius (CCR) curves for PP to quantitatively correlate the viscoelasticity and foamability and evaluate the foamability of PP combined with batch foaming. It is shown that with increasing branching degree, the foam shows a better resistance to bubble coalescence , resulting in a more regular bubble structure and a higher expansion ratio. Moreover, viscosity should be controlled over an appropriate range for realising good foamability; otherwise, excessive viscosity can suppress bubble growth and limit the expansion ratio. MPPZ4 modified with 4 wt% TMPTA and 0.4 wt% ZDMC showed the best foamability. A combination of the PBB model and batch foaming experiment is used to quantitatively explain the contribution of LCB to foaming.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
ACS Applied Polymer Materials
·
2024
·
IF 4.4
Yehan Yang,Mengxia Xu,Zhu Luo,Ruhui He,Jikai Xie,Shenglong Yang,Hu Chen,Huaibin Li
To address the compatibility challenges between polypropylene (PP) and poly(ethylene terephthalate) (PET), a long-chain-branched polypropylene compatibilizer featuring ester groups (LCB-PP-E) was synthesized from PP and pentaerythritol triacrylate (PETA), facilitated by the initiator dicumyl peroxide. The structure of LCB-PP-E was characterized by using infrared spectroscopy, rheology, and melt flow index analysis, while potential reaction mechanisms were discussed. The morphology of the blend was examined by scanning electron microscopy and Raman spectroscopy. The effects of LCB-PP-E on the thermodynamic and crystallization behavior of PP/PET blends were studied by dynamic mechanical analysis, differential scanning calorimetry, and polarizing microscopy. LCB-PP-E sampled at the reaction peak point exhibited a longer branched PP chain compared to that of LCB-PP-E obtained at the balance torque, facilitating better entanglement with PP macromolecules. Furthermore, the ester groups on LCB-PP-E engaged in transesterification reactions with the ester groups on the PET chains. The combined effects of these interactions effectively reduced the interfacial tension between the two phases, resulting in a decreased size of the dispersed PET phase and a more uniform distribution. Additionally, the introduction of LCB-PP-E significantly narrowed the crystallization and glass transition temperature difference between the phases. The enhanced compatibility led to an increase in elongation at break, demonstrating a transition of the blend from a brittle material to a ductile material. This compatibilization system shows substantial potential for high-quality applications in PP/PET recycled plastics.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
·
IF 3.573
Jianan Cai,Zhipeng Liu,Bo Cao,Xiaoxiao Guan,Shumei Liu,Jianqing Zhao
Simultaneously improving the mechanical properties and processability of polyamide-6 (PA6) by chain extension in melting extrusion is usually very difficult. To address this issue, a novel small-molecule triepoxy chain extender (D1) is designed, synthesized, and used to modify PA6. The rheological measurements show that the shear viscosity of PA6 containing 2 wt % D1 decreases by 52.2% compared with that of the original PA6 at a shear rate of 1000 s–1, which is in the shear rate range of thermoplastic processing in the industry. This interesting result is attributed to the generation of a long-chain-branched structure of the macromolecular chains of chain-extended PA6, which reduces the power-law index and aggravates the shear-thinning behavior of the PA6 melt. In addition, the corresponding notched impact strength increases from 62.4 to 105.9 J/m. As a result, this work provides a feasible way to prepare PA6 with excellent mechanical properties and processability in industrial production.
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 BIOMEDICAL MATERIALS RESEARCH PART A
·
2019
·Vol. 107
·期 11
·2458-2467
·
IF 3.221
Zhengqiu Li,Lei Liu,Baoshu Chen,Tianbao Zhao,Longchang Ran,Xiaodie Yuan,Zhiwen Cao,Ting Wu
Long-chain branched poly (lactic acid) (LCB-PLA) with antimicrobial functional group was fabricated through a two-step ring-opening reactive processing for improving antimicrobial properties and broadening the PLA processing window. A combination of linear viscoelasticity and the branch-on-branch (BOB) model predicted probable compositions and chain topologies of the products. It is also explored the antimicrobial properties of LCB-PLA to provide a theoretical basis for broadening the possible applications.
研究领域:
材料科学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
International Journal of Environmental Research
·
2024
·Vol. 18
·期 4
·1-12
·
IF 2.6
Feng Meiyun,Xu Zhiqiang,Lin Kuangfei,Zhang Meng
The biodegradable film that exhibited excellent physical barrier properties and the function to degrade smelly organic pollutants (SOP) had been successfully synthesized in this study. The organic intercalation-modified bentonite that loaded with CaO 2 (OBT@CaO 2 ) was synthesized initially, which would serve as a layered nano-filler to modify the long-chain (polybutylene adipate-co-terephthalate) branched polylactic acid (PLA/PBAT), to produce the SOP diffusion control film (OBT@CaO 2 -PLA/PBAT, OCPP). OBT@CaO 2 could improve the initial tensile strength (46.5 ± 6.53 MPa) and elongation at break (412.8 ± 9.25%) of OCPP film, and the O 2 transmission rate was as low as 44.89 cc/m 2 ∙day. Although the saturated adsorption capacity of SOP on OBT@CaO 2 decreased with olfactory thresholds, the penetration time correspondingly increased due to reduced degradation difficulty. OCPP film showed excellent SOP control performance in laboratory and large-scale tests at actual pesticide industrial contaminated sites (PICSs). The diffusion fluxes of SOP exhibited a reduction of at least 84.0% within 14 days, and the effectiveness of SOP control increased over time. This improvement is attributed to the gradual release of H 2 O 2 by OBT@CaO 2 , enabling the effective degradation of SOP that adsorbed on it, thereby continuously providing adsorption sites. The research can provide a low-cost and green approach for long-term diffusion control of SOP at contaminated sites that are not limited to PICSs. Graphical Abstract
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Chenyang Li,Weiguang Gong,Zhaopeng Deng,Zhongyang Yao,Xin Meng,Zhong Xin
A biobased modifier, epoxidized cardanol, was used as a multifunctional coagent to develop long-chain branched polylactic acid (LCB-PLA) together with peroxide by a one-step reaction. The molecular structure of LCB-PLA was evaluated from weight-average molecular weight, intrinsic viscosity, and shear rheology. The results showed that the branching degree of LCB-PLA was enhanced with the increased addition amount of epoxidized cardanol due to the unique structure consisting of an epoxy group and a long carbon chain with multiple unsaturated bonds. The generated LCB-PLA exhibited improved crystallization performance and significant heat resistance. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) analyses showed that the long-chain branched structure could play the role of a nucleation site, resulting in the improved crystallization performance of PLA. Especially, for 0.3 wt % peroxide-modified PLA with 0.8 wt % epoxidized cardanol (PLA/0.3T/0.8E), the crystallinity of LCB-PLA reached approximately 44%, increasing the Vicat softening temperature (VST) and heat deflection temperature (HDT) to 156.2 and 82.5 °C, respectively, after a simple annealing treatment. Moreover, the annealed LCB-PLA exhibited better hydrolysis resistance than linear PLA in the early degradation stage, while it degraded rapidly in the later stage. In short, this work provided a green route to obtain LCB-PLA, which exhibited excellent crystallization properties and heat resistance.
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
POLYMER SCIENCE SERIES B
·
2025
·
IF 1
Weijie Xie,Zhang Shaojie,Gong Xiangyun,Zhao Caixia,Zou Guoxiang
In this study, we employed two distinct branching coagents to optimize the topology structure of long-chain branched polylactide (LCB-PLA) via melt grafting with 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane (Trigonox301) and PLA. Our findings reveal that an impressive 22.8% degree of branching degree in PLA was attainable with the addition of merely 2 wt % allyl glycidyl ether (AGE) and 0.75% Trigonox301. Three mathematical models were applied to quantitatively assess the degree of branching based on molecular weight distribution, zero-shear viscosity η 0 , and phase angle. Notably, the presence of gel complicated the precise determination of the branching degree when using LCB G derived from molecular weight distribution fitting. Comparatively, the η 0 and LCB C , derived from complex viscosity fitting for LCB-PLA samples enriched with 2 wt % AGE, saw a marked escalation from 2140 Pa s and 0 mol % to 13286 Pa s and 22.8 mol %, respectively. Furthermore, the preferential end-group reaction between the epoxy group of AGE and the carboxyl group of the PLA molecule chain indicated that AGE was more efficacious in enhancing the branching degree than trimethylolpropane triacrylate (TMPTA).
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMERS AND THE ENVIRONMENT
·
2021
·Vol. 30
·期 3
·1127-1140
·
IF 3.667
Wang Jun,Yang Le,Li Xiaolong,Luo Zhu,Li Jianjun,Xia Xiaosong,Linghu Changkai
Incompatible polypropylene (PP) and polyethylene (PE) are difficult to separate in mixed recycling streams such as waste plastic packaging, which makes polyolefin mixtures unsuitable for high-quality products. In this work, based on the free radical branching reaction, a co-branching reaction of isotactic polypropylene (iPP) and high-density polyethylene (HDPE) blends was carried out in the presence of the peroxide, free radical regulator and multifunctional acrylate monomer, and a star-like long-chain branching (LCB) copolymer was obtained. The effect of in situ compatibilization on the structures and mechanical properties of iPP/HDPE was investigated, and the compatibilization mechanism was discussed. Results showed that the mechanical properties of the modified blends were largely improved, and efficient in-situ compatibilization of iPP and HDPE could be taken place in a wide process window. Moreover, the sizes of the dispersed phase in the modified blends were clearly decreased, and the interfacial thickness increased. Compared with the pure iPP/HDPE blend, the initial crystallization temperature of iPP in the modified iPP/HDPE blend was increased, and long branched chains of the LCB copolymers were physically entangled with the chemical identical homopolymers or even participated in the crystallization of iPP and HDPE. Thanks to the in situ compatibilization strategy, the compatibility of iPP/HDPE was significantly improved.
研究领域:
材料科学
·
聚合物工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CELLULAR PLASTICS
·
2023
·
IF 2.5
Jing Cao,Jingwen Zou,Siying Zheng,Na Wen,Weijie Xu,Yuying Zheng
The foaming of PP has encountered challenges because of its low melt strength and semi-crystalline characteristics. Introducing long chain branching (LCB) onto the PP backbone and the addition of particles as cell nucleating agent are the commonly used methods to improve the cell structure of PP foams. In this paper, clay-supported sodium benzoate (NaB-OMMT) was prepared from Na-montmorillonite (Na-MMT) via the partial ion exchange reaction with surfactant and subsequent reaction with benzoic acid. The as prepared NaB-OMMTs were then applied to prepare LCBPP/NaB-OMMT nanocomposites and their foams. The dispersion state of clay, crystallization behaviors and rheological properties of the nanocomposites, as well as the cell structure and compression properties of the foams were investigated. The results show that clay layers are mostly exfoliated in the nanocomposites with low NaB-OMMT content, while intercalated layers dominant with the content reaches 2% or higher. The melting temperature of the nanocomposites decreases and the crystallinity increases, while the spherulite size decreases compared to LCBPP. The melt viscosity and elasticity of nanocomposites increase significantly when the content of NaB-OMMT reaches 2% or higher. LCBPP/NaB-OMMT nanocomposites foams exhibit higher cell density, smaller cell size and its standard deviation. Therein, the foam with 1% of NaB-OMMT shows the maximum cell density and the minimum cell size. It is concluded that the cell structure of the foam is highly dependent on the content, dispersion state and structure of the cell nucleating agent. When NaB is supported on well dispersed and exfoliated clay layers, the cell nucleation efficiency is significantly enhanced. The compression properties of the foams depend on their cell structures and exhibit the similar variation trend with the latter with the content of NaB-OMMT increasing.
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
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Yueling Chen,Wenchao Yang,Zikang Hu,Xiaoyan Gao,Jingbiao Ye,Xiangqian Song,Baoshu Chen,Zhengqiu Li
In order to solve the problem of uneven microporous structure of Poly(L-lactic acid) (PLLA) bulk orientation by using biological safety multi-functional plant oil as chain extenders (CE), multi-armed flexible chains were introduced into PLLA through reactive processing to prepare long chain branched PLLA (LCB-PLLA). When the total content of the CE was 6.15 wt%, PLLA and the CE reacted most fully, while maintaining the tensile strength of PLLA and improving toughness. After introducing the LCB structure, the presence of multi-armed flexible chains increased the mobility of the molecular chains, resulting in a significantly lower degree of crystallinity. When the draw ratio up to 900 %, the crystallinity of LCB-PLLA-F-900 % was only 45.15 %, lower than that of PLLA-F-900 %. Thanks to the mobility of polymer chains can be enhanced, which reduces the degree of crystallinity while promoting the uniform growth of oriented microporous structures. Finally, an oriented micro-porous biomimetic LCB-PLLA material with an average cell diameter of 540 nm was prepared, and the results of in vitro cell culture showed that the oriented micro-porous LCB-PLLA biomimetic material was more conducive to cell proliferation.
研究领域:
材料科学
·
生物医学工程
·
高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Polymer Chemistry
·
2016
·Vol. 7
·期 21
·3551-3561
·
IF 5.687
Xiaohang Han,Yangguang Hu,Miao Tang,Huagao Fang,Qianghua Wu,Zhigang Wang
In this study a series of long chain branched polycarbonates (LCB-PCs) was prepared from linear PC precursors through gamma radiation with addition of a difunctional monomer, divinyl benzene (DVB) of varying amounts. The topological structures of the linear PCs and LCB-PCs were measured by size-exclusion chromatography coupled with a multiangle light scattering detector (SEC-MALLS) and rheology. SEC-MALLS measurements showed that the topological structures of the PCs were changed with the introduction of LCB structures. Rheological measurements showed that the LCB structures of the LCB-PCs contributed to enhancements of storage modulus, complex viscosity, shear-thinning behavior, and the deviation of phase angle, δ, from the “standard” curve of linear PCs in the δ − |G*| plots (van Gurp–Palmen plot). Modulated differential scanning calorimetry (MDSC) measurements showed that the glass transition temperature, Tg, of LCB-PCs decreases with increasing LCB degree, which is attributed to the combined effects of both increased branching density and free chain ends. LCB structures introduced into PCs did not apparently weaken the tensile properties of the PC materials, whereas the notched Izod impact strength could be obviously improved by the LCB structures. More importantly, the influence of LCB structures on the environmental stress cracking (ESC) behavior of LCB-PCs was explored and the results indicated that the ESC properties of LCB-PCs could be significantly enhanced with the introduction of LCB structures, which makes the application of LCB-PCs as the window view materials for helmets worn by astronauts while in outer space a possibility.
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
RSC Advances
·
2019
·Vol. 9
·期 2
·1123-1133
·
IF 3.049
Lijin Xie,Xiaokun Liang,Hongwei Huang,Le Yang,Feng Zhang,Xiaolong Li,Zhu Luo
A compounded nanoparticle with multiple double bonds (CC) was prepared by grafting glycidyl methacrylate (GMA) onto the surface of nano-SiO2. Then gel-free long chain branched polyethylene (LCBPE) was prepared by melt branching reaction in a Haake torque rheometer in the presence of initiator peroxide and GMA grafted nano-SiO2 (SiO2-g-GMA). The sampling time corresponded to the summit of the reaction peak in the torque curve. Fourier transform infrared results indicated that SiO2-g-GMA had been grafted onto the HDPE backbone via radical reaction. The reaction mechanism and the topological structure of the PE products are also discussed. Rheological results showed that the relaxation time and molecular weight distribution of modified PE were increased owing to the introduction of LCB structure, and the more SiO2-g-GMA was added, the more apparent variation could be observed. Compared with linear HDPE, both the melt strength and mechanical properties of LCBPE were improved obviously. From the differential scanning calorimetry and polarized optical microscopy results, smaller crystal size and lower growth rate were observed compared with linear HDPE, which are ascribed to the nucleation and restriction of long branching chains in the system. Well distributed nano-SiO2 without any agglomeration in the PE matrix was observed in the scanning electron microscope images when the SiO2-g-GMA content was less than 3 phr.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）