长支链
- 网络long-chain branch;long chain branch;lcb
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长支链结构增大了分子折叠链自由能,在结晶形成过程中,分子链更不容易折叠回到片晶中排列,因而长支化结构促进了γ晶的形成。
LCB structure increases the chain folding energy and makes molecular chain fold back more hardly , so it will facilitate the formation of γ crystal .
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产物聚乙烯支化度为17%,13cNMR分析结果表明,含有甲基、丁基和长支链。
13 C NMR analysis reveals there are methyl , butyl and long branches at polyethylene backbone .
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研究结果表明,将长支链引入线性PP中会显著改变PP流变行为,导致PP熔体显示出更长的松弛行为。
The results showed that the long branch chain could change the rheological behavior of the samples evidently and result in a longer relaxation process .
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~(13)C-NMR研究聚丁二烯长支链支化
Study of long-chain branching in polybutadiene by ~ ( 13 ) c-nmr spectrometry
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通过辐照法制备了长支链型高熔体强度聚丙烯(LCB-HMSPP),采用高级流变扩展系统(ARES)表征了其熔体黏弹性,采用毛细管流变仪研究了其在高剪切速率下的流变行为。
High-melt-strength polypropylene with long chain branching ( LCB-HMSPP ) was prepared via irradiation .
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发现13cNMR谱和DRI指数在一定程度上一致反映了mPEs的长支链结构;
The results showed that to some extent , 13C NMR spectra were in accord with the values of DRI for characterizing the long branching level in mPEs .
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实验结果显示,随枝化链含量上升,LCBPP结晶行为对流场的响应变得更加敏感,长支链的引入加速了PP成核动力学。
The results showed that the LCB PP samples became more and more sensitive to the flow fields with the content of the branched component increasing ; moreover , long branched chains also accelerated the nucleation kinetic of polymer samples .
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但当mPEs中存在的少量长支链时,mPEs的流变性能受其影响很大,导致了DRI指数与13cNMR谱结果差异,以至影响了DRI指数的应用范围。
However , fewer long branching level had great effect on the rheological behavior of mPEs so as to result in differences between 13C NMR spectra and the values of DRI .
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与PHB/CAB共混物相比,由于PEG长支链的引入,PHB/CAB-g-PEG共混体系具有更好的相容性,因此韧性明显提高,拉伸时呈现出韧性断裂的特征。
Unlike PHB / CAB blends , PHB / CAB-g-PEG blends were miscible system because of the introduction of PEG long side chain . So the toughness of these blends was much better than PHB / CABblends and showed obvious characteristic of tenacity fracture .
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13C核磁共振谱分析结果表明,催化剂体系Ⅰ制备的聚乙烯产物的支链全部为长支链(支链碳原子数大于等于6),而催化剂体系Ⅱ制备的聚乙烯则含有长支链和侧甲基;
~ ( 13 ) C NMR indicated that branched chain polyethylene with long chain branch es ( carbon number more than 6 ) was only synthesized on Cat ⅰ, while polyethylene with methyl pendants and long chain branch was prepared over Cat ⅱ .
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辐照改性制备长支链型高熔体强度聚丙烯(LCB-HMSPP)流变行为及挤出发泡的研究
Research on High-Melt-Strength Polypropylene with Long-Chain-Branching Structure ( LCB-HMSPP ) Prepared by ~( 60 ) Co - γ Irradiation : Rheological Properties and Applications in Extrusion Foaming
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长支链结构对等规聚丙烯结晶行为的影响
Effect of long chain branched structure for isotactic polypropylene on crystallization behaviors
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天然纤维素蒸汽闪爆改性对其长支链酯合成影响
Effect of Steam Explosion on Synthesizing Long Chain Cellulose Ester
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长支链型高熔体强度聚丙烯流变性能的研究&剪切流变
Rheological Behavior of High-melt-strength Polypropylene with Long-chain-branching Structure-Shear Rheology
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长支链聚丙烯的制备与表征
Synthesis and Characterization of Long Chain Branched Polypropylene
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研究表明:成功合成了具有长支链和梳型结构特点的两性聚丙烯酰胺。
The study showed that the as prepared PAM had long branched chain and comb structure .
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但是对于梳形聚合物与不对称星形聚合物来说,在一定范围内单凭线性粘弹性是难以进行区分的,这表明线性流变学在表征长支链聚合物时是存在局限的。
However , it is difficult to distinguish the asymmetric star and comb polymers only by the linear viscoelasticity .
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在苯乙烯存在下只需较低的引发剂用量,经历一定的反应时间就有长支链形成。
It was also found that long chain branches can be formed at rather low initiator feed in the presence of styrene .
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随着温度的升高聚乙烯产物支化度和甲基支链含量都迅速增加,长支链含量则显著下降。
Branching degree of the polyethylenes and the content of methyl branch rise quickly with reaction temperature , but the content of long branches drops remarkably .
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而由Ni+Mo催化体系聚合的试样,可能为1,2-乙烯基的双键打开接长支链。
For samples polymerized from Ni + Mo catalysts systems , branching point is formed through the opening of the double bond of 1,2 vinyl group .
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反应温度、引发剂用量、单体用量以及反应时间等因素对长支链的形成也有影响。
The formation of long chain branches was affected by factors such as reaction temperature , feed ratio of initiator , styrene feed and reaction time .
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茂金属聚乙烯的分子链长支化结构对其流变特性有重要影响,长支链可以使熔体弹性和剪切变稀效应明显增强。
The molecular long chain branch structure of metallocene polyethylene has great effects on it 's rheological behavior , long chain branch can significantly enhance melt elasticity and shear thinning .
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双烷基过氧化物在短支链助交联剂的配合下,使乙丙二元共聚丙烯和长支链的乙-辛烯共聚物产生网状交联结构。
Crosslinked network structure of COPP and POES with long branched chain was formed by the combination effect of double alkyl peroxide and auxiliary crosslinking agent with short branched chain .
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分析了聚合物的结构因素包括熔体流动速率、长支链、共聚单体和相对分子质量分布以及测试条件包括温度、挤出速率和拉伸长度对熔体强度的影响。
Some factors affecting melt strength are analysed such as polymer structure factors including melt index , long chain branching , comonomer type and molecular weight distribution and measuring conditions incorporating temperature , extrusion rate and draw distance .
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产物具备长支链聚合物的一般特征,流变行为得到了大大改善,如低频剪切储存模量增加、损耗角变小、复数粘度增大、剪切变稀程度降低等。
The products possessed the general characteristics of long chain-branched polymer and the rheological behavior has been obviously improved , such as higher value of stored module at low frequency , distinct decrease of loss angle , significant increase of complex viscosities and shear thinning less sensitive .
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选用局部坐标系和球铰的转角描述了动平台的位置,分析了运动副转角、杆长、支链干涉等因素对并联机器人工作空间的影响。
By adopting the partial coordinates system and the turning angle of globe hinge the position of moving platform was described , and the influence on working space of parallel robot affected by factors of turning angle of motion pair , rod length and interference of branch chain etc.
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双突变还降低了短(聚合度(DP)5-6)和长(DP12-23)支链淀粉链的含量、增加了中长型(DP7-11)支链淀粉的含量。
The double mutation also reduced short ( degree of polymerization ( DP ) 5 – 6 ) and long ( DP12 – 23 ) amylopectin chain contents in the grain and increased the medium long types ( DP7 – 11 ) .
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氨基磺酸系减水剂的长主链、多支链、多极性基团的分子结构特点决定其在水泥颗粒表面的吸附特性。
The adsorption characteristic on the surface of cement particals can be attributed to the molecule structure of ASPF .
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对于配比为80/20的线形聚丙烯/长链支化聚丙烯共混物,由于长支链的存在,降温速率越慢,结晶温度越高。
For the blend that the mass rate of linear polypropylene / long chain branching polypropylene is 80:20 , its crystallization temperature goes up with a reduction in cooling rate because of the presence of long chain branding polypropylene .