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Copolymerization of styrene with butadiene using methyl tert‐butyl ether as active center modifier 以甲基叔丁基醚为活性中心改性剂的苯乙烯与丁二烯共聚反应
Pub Date : 1999-11-01 DOI: 10.1002/(SICI)1522-9505(19991101)271:1<18::AID-APMC18>3.0.CO;2-#
M. Iovu, E. Buzdugan, M. Teodorescu, A. Britchi, G. Hubca, H. Iovu
The copolymerization reaction of styrene with butadiene was performed using n-butyllithium (BuLi) as initiator and methyl tert-butyl ether (MTBE) as active center modifier. The randomness of the copolymers increases with decreasing polymerization temperature and increasing [MTBE]/[BuLi] molar ratio. The solvent and the modifier/initiator ratio strongly influence the copolymerization rate. In comparison with other modifiers, MTBE exhibits a moderate action on rate and selectivity of styrene-butadiene copolymerization. The reaction rate increases as the [MTBE]/[BuLi] molar ratio increases from 7 to 40. At higher [MTBE]/[BuLi] molar ratios, the copolymerization rate decreases. First partial reaction orders with respect to styrene and butadiene were calculated. No transfer reactions were detected in cyclohexane, but these are evident in toluene. The microstructure of the butadiene units incorporated into the copolymer chain is little influenced by the polymerization temperature. Higher [MTBE]/[BuLi] molar ratios will lead to an increase in the number of butadiene units incorporated as vinyl units.
以正丁基锂(BuLi)为引发剂,甲基叔丁基醚(MTBE)为活性中心改性剂,进行了苯乙烯与丁二烯的共聚反应。随着聚合温度的降低和[MTBE]/[BuLi]摩尔比的增大,共聚物的随机性增大。溶剂和改性剂/引发剂的比例对共聚速率有很大影响。与其他改性剂相比,MTBE对丁苯共聚的速率和选择性有中等程度的影响。[MTBE]/[BuLi]的摩尔比从7增加到40,反应速率随之增加。在较高的[MTBE]/[BuLi]摩尔比下,共聚速率降低。计算了苯乙烯和丁二烯的一偏反应阶数。在环己烷中没有检测到转移反应,但在甲苯中这些反应很明显。聚合温度对共聚物链中丁二烯单元的微观结构影响不大。较高的[MTBE]/[BuLi]摩尔比将导致作为乙烯基单元的丁二烯单元的数量增加。
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引用次数: 11
Comparison of poly(2,5-dibutoxy-p-phenylenevinylene)s synthesized by two different methods 两种不同方法合成聚(2,5-二丁氧基-对苯乙烯)的比较
Pub Date : 1999-09-01 DOI: 10.1002/(SICI)1522-9505(19990901)270:1<56::AID-APMC56>3.0.CO;2-#
H. Xie, Chengyong Liu
Poly(2,5-dibutoxy-p-phenylenevinylene)s (PDBOPVs) were synthesized by two different methods, namely the organosoluble precursor method followed by thermal treatment, and phase transfer catalysis. Both the organosoluble precursor and PDBOPV were characterized by elemental analysis, IR spectrophotometry, UV-Vis spectrophotometry, gel permeation chromatography, thermal gravimetric analysis and differential scanning calorimetry. Factors affecting the synthesis of PDBOPV via the phase transfer catalysis, such as kind and amount of phase transfer catalyst, kind of solvent, reaction time as well as NaOH concentration were studied. Yield, molecular weight, solubility, conductivity and electroluminescent properties of PDBOPVs were compared. The results showed that the yield and solubility of PDBOPV obtained by phase transfer catalysis are higher than those of PDBOPV obtained by the organosoluble precursor method. However, molecular weight, conductivity and electroluminescence of PDBOPV obtained by the organosoluble precursor method are much higher than those of PDBOPV obtained by the phase transfer catalysis method. Conditions for thermal elimination of the organosoluble precursor to improve the electroluminescent properties were also investigated.
采用两种不同的方法合成了聚(2,5-二丁氧基-对苯乙烯)s (PDBOPVs),即有机可溶性前驱体法-热处理法和相转移催化法。采用元素分析、红外分光光度法、紫外可见分光光度法、凝胶渗透色谱法、热重分析和差示扫描量热法对有机可溶性前驱体和PDBOPV进行了表征。研究了相转移催化剂的种类和用量、溶剂种类、反应时间以及NaOH浓度等因素对相转移催化合成PDBOPV的影响。比较了PDBOPVs的产率、分子量、溶解度、电导率和电致发光性能。结果表明,相转移催化制得的PDBOPV收率和溶解度均高于有机可溶性前驱体法制得的PDBOPV。然而,有机可溶性前驱体法制备的PDBOPV分子量、电导率和电致发光均远高于相转移催化法制备的PDBOPV。研究了热消除有机可溶性前驱体以改善电致发光性能的条件。
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引用次数: 0
Electro‐optic birefringence and scattering of concentrated solutions of ethylcellulose 乙基纤维素浓溶液的电光双折射和散射
Pub Date : 1999-07-01 DOI: 10.1002/(SICI)1522-9505(19990701)268:1<1::AID-APMC1>3.0.CO;2-#
G. Maitland, O. P. Nwammuo
Photon correlation spectroscopy (PCS) at small scattering vector (kR G ≃ ) and the same is true for the broadening parameters of the decay and rise transients (β r ≃ β d ). The β values were found to decrease with increasing concentration. The experimental results are in qualitative agreement with the theoretical prediction of Doi and Edwards but in quantitative disagreement; thus implying that idealised models are far from describing the true observation. The semi-empirical theory of Douglas and Hubbard aptly described the concentration exponents observed in this work for the zero shear viscosity and the whole chain relaxation data.
光子相关光谱(PCS)在小散射矢量(kR G)处和衰减和上升瞬态(β r)的增宽参数处均具有相同的特征。β值随浓度的增加而降低。实验结果在定性上与Doi和Edwards的理论预测一致,但在定量上不一致;这意味着理想化的模型远远不能描述真实的观察结果。道格拉斯和哈伯德的半经验理论恰当地描述了本工作中观察到的零剪切粘度和全链弛豫数据的浓度指数。
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引用次数: 0
Photovieillissement d'un copolymère d'éthylène et d'acétate de vinyle en présence de sueur artificielle. II. Evolution morphologique 乙烯和醋酸乙烯共聚物在人工汗液存在下的光老化。二。进化形态学
Pub Date : 1999-05-01 DOI: 10.1002/(SICI)1522-9505(19990501)266:1<50::AID-APMC50>3.0.CO;2-#
C. Dubois, V. Rigny-Bourgeois, A. Chambaudet
Un copolymere d'ethylene et d'acetate de vinyle (EVA) a ete photovielli, en presence de sueur artificielle, dans une cellule amenagee a cet effet. D'autre part, le photovieillissement a ete realise sans sueur artificielle afin d'apprehender le role de ce substrat. Des etudes similaires ont egalement ete conduites sur cet EVA contenant des stabilisants lumiere. L'evolution morphologique des phases cristallines a ete etudiee par calorimetrie differentielle a balayage en suivant, principalement l'evolution des temperatures correspondant aux pics de fusion, et en second lieu celles des temperatures de transitions vitreuses et des enthalpies de fusion. Ainsi, il est possible d'interpreter la reorganisation des deux phases cristallines presentes dans l'EVA neuf, l'une riche en motifs vinyle acetate (VA) et l'autre riche en motifs polyethylene (PE), et de preciser l'action de la temperature, de la photolyse et de la sueur, en presence ou en absence de stabilisants. An artificial photoaging cell was arranged with the goal to study the behaviour of polymers partly immersed in artificial sweat. A poly(ethylene-co-vinyl acetate) (EVA) was photoaged in this cell. On the other hand, photoaging was realized without artificial sweat in order to understand the action of this substrate. Similar studies were carried out with light stabilized EVA. The morphological evolution of the crystalline structures of the polymer was studied by differential scanning calorimetry, mainly the evolution of the melting temperatures, and secondly those of the glass transition temperatures and of the melting enthalpies. Thus, it was possible to understand the reorganization of two crystalline structures contained in the fresh EVA, the first one rich in poly(vinyl acetate) and the second one in rich in polyethylene.
乙烯和醋酸乙烯酯(EVA)的共聚物在一个有这种效果的细胞中,在人工汗液的存在下进行了photovielli。此外,光老化是在没有人工汗水的情况下进行的,以保证这种基质的作用。类似的研究也在这种含有光稳定剂的EVA上进行。用差示扫描量热法研究了结晶相的形态演变,主要是监测与熔合峰相对应的温度演变,其次是玻璃化转变温度和熔合焓。从而感染流行性感冒的动物,有可能结晶团队设计两个阶段的eva九个盛产的理由之一,乙酸乙烯(VA)和另一种富含理由:聚乙烯(PE)、温度、行动和魁松光解和汗水,存在或缺少稳定剂。= =地理= =根据美国人口普查,这个县的面积为,其中土地面积为,其中土地面积为。在这个细胞中,聚乙基共乙烯醋酸酯(EVA)被拍摄下来。另一方面,为了了解这种物质的作用,在没有人工汗的情况下进行了光aging。类似的研究也在光稳定的EVA中进行。形态进化of The crystalline圣母polymer was studied by微分结构,扫描calorimetry咸水的进化》,熔点温度,and多少话of The glass)和圣母熔点温度过渡焓。Thus, it was知道可能的重组问题》two in the fresh crystalline结构这娃,rich in the first one聚乙酸乙烯酯(聚乙烯)and the second one in rich in。
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引用次数: 1
N‐Oxyl‐kontrollierte radikalische Lösungspolymerisation von Styrol N‐Oxyl‐控制radikalische Lösungspolymerisation Styrol的
Pub Date : 1999-03-01 DOI: 10.1002/(SICI)1522-9505(19990301)265:1<47::AID-APMC47>3.0.CO;2-#
Marco Drache, A. Koch, G. Schmidt-Naake
The radical solution polymerization (solvent: anisole) controlled by 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) makes possible to synthesize block copolymers with higher molecular weights, as well as to polymerize solid monomers. Polystyrene previously terminated by TEMPO was employed as a macroinitiator, which was then polymerized at various styrene/anisole ratios, temperatures, and initiator concentrations (initiator: dicumyl peroxide). In addition, model calculations were employed to study the initiator-based acceleration and to simulate the product composition of the resulting polymer. The controlled radical polymerizations in solution and in bulk can be performed through dosed initiator addition with comparable rates of polymerization.
2,2,6,6-四甲基哌啶- n -氧基(TEMPO)控制的自由基溶液聚合(溶剂:苯甲醚)使得合成高分子量嵌段共聚物和聚合固体单体成为可能。先前用TEMPO终止的聚苯乙烯作为宏观引发剂,然后在不同的苯乙烯/苯甲醚比例、温度和引发剂浓度(引发剂:过氧化二氨基)下进行聚合。此外,采用模型计算研究了基于引发剂的加速,并模拟了所得聚合物的产物组成。在溶液和散装中控制自由基聚合可以通过添加剂量引发剂以相当的聚合速率进行。
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引用次数: 2
Thickness distribution of degradation products during photochemical aging of rigid PVC 硬质PVC光化学老化过程中降解产物的厚度分布
Pub Date : 1998-12-01 DOI: 10.1002/(SICI)1522-9505(19981201)261-262:1<25::AID-APMC25>3.0.CO;2-#
L. Audouin, C. Anton-Prinet, J. Verdu, G. Mur
The photooxidation of bulk (1 mm) and thin (∼80 μm) samples of unfilled PVC free of photostabilizers was studied in various photoreactors in the 40-70°C temperature range. In bulk samples, the thickness distributions of photoproducts (carbonyls, conjugated polyenes, chain scission, crosslinks) and thermal stabilizer (Zn/Ca stearate) were established using various analytical methods from measurements made on 20 μm microtome slices parallel to the irradiated surface. The experimental results clearly reveal the existence of the following three distinct zones across the sample thickness, starting from the irradiated surface: i) A thin (<100 μm) superficial layer rich in oxidation products and in which chain scissions predominated. ii) A subcutaneous layer extending up to 400 μm depth, containing essentially polyenic species and in which crosslinking predominated. iii) A non degraded core zone beyond about 400 μm depth. During UV exposure, the subcutaneous maximum of polyene concentration moves towards the surface whereas the superficial oxidized layer keeps an almost constant thickness, practically independent of irradiation conditions. These features, and the kinetic data obtained on thin films, are consistent with a mechanistic scheme close to standard one, but in which polyenes (and crosslinks) are generated from alkyl (P°) radicals. These latter can survive at a given distance from the sample surface, because oxidation is diffusion controlled. This behavior is further complicated by the fact that after a certain exposure time the screen effect by the polyene layer takes the control of the thickness distribution of the reactive species.
在不同的光反应器中,在40-70°C的温度范围内,研究了不含光稳定剂的散装(1 mm)和薄(~ 80 μm)未填充PVC样品的光氧化。在大量样品中,通过平行于辐照表面的20 μm切片,利用各种分析方法建立了光产物(羰基、共轭多烯、断链、交联)和热稳定剂(锌/硬脂酸钙)的厚度分布。实验结果清楚地表明,从辐照表面开始,在样品厚度上存在以下三个不同的区域:i)一个薄(<100 μm)的表面层富含氧化产物,并且以链断裂为主。ii)延伸至400 μm深度的皮下层,主要包含多基因物种,并以交联为主。iii)深度超过约400 μm的岩心区域未退化。在紫外线照射期间,皮下最大多烯浓度向表面移动,而表面氧化层的厚度几乎保持恒定,几乎与照射条件无关。这些特征以及在薄膜上获得的动力学数据与接近标准的机制方案一致,但其中多烯(和交联)是由烷基(P°)自由基产生的。后者可以在离样品表面一定距离的地方存活,因为氧化是扩散控制的。在一定的曝光时间后,多烯层的屏蔽效应控制了反应物质的厚度分布,这一事实使这种行为进一步复杂化。
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引用次数: 20
Studies on the aging processes of polymers in electrical systems 电气系统中聚合物老化过程的研究
Pub Date : 1998-12-01 DOI: 10.1002/(SICI)1522-9505(19981201)261-262:1<143::AID-APMC143>3.0.CO;2-#
C. Mayoux
After a definition of electrical systems in which polymers play the role of the insulating material, the macroscopic failures occurring in the polymer under working conditions are presented. Some aspects of aging, like electrical or water treeing, are considered dependent on the morphology and the induced characteristics of the insulating material. The understanding of the aging process of LDPE and XLPE is achieved through the use of original techniques, e.g. electroluminescence, confocal laser scanning microscopy, thermally stimulated crcep. The slow degradation of the polymer characterized by the break of bonds may lead to submicrocracks which coalesce to produce defects of critical sizes. Indeed, it is shown how the presence of gas-filled cavities in the insulating material is one of the causes of breakdown. The synergistic effect of the discharge species impinging on the polymer is prescnted. The discharge activity is cxtended to new insulating materials like poly(ethylene 2,6-naphthalate) (PEN) films. An overview of the rccent models is given in conclusion to point out the needs for a better understanding of the aging mechanisms.
在定义了以聚合物为绝缘材料的电气系统后,给出了在工作条件下聚合物中发生的宏观失效。老化的某些方面,如电树或水树,被认为取决于绝缘材料的形态和诱导特性。对LDPE和XLPE的老化过程的了解是通过使用原始技术,如电致发光,共聚焦激光扫描显微镜,热刺激蠕变。以键断裂为特征的聚合物的缓慢降解可能导致亚微裂纹,这些亚微裂纹合并产生临界尺寸的缺陷。实际上,它显示了绝缘材料中充满气体的空腔的存在是击穿的原因之一。提出了放电物质与聚合物碰撞的协同效应。放电活性扩展到新型绝缘材料,如聚乙烯2,6-萘二甲酸酯(PEN)薄膜。最后,对最近的模型进行了概述,指出了更好地理解老化机制的必要性。
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引用次数: 5
Inverse microemulsion polymerization of acrylamide in the presence of N,N-dimethylacrylamide N,N-二甲基丙烯酰胺存在下丙烯酰胺的反相微乳液聚合
Pub Date : 1998-08-01 DOI: 10.1002/(SICI)1522-9505(19980801)258:1<27::AID-APMC27>3.0.CO;2-#
V. Juraničová, Sakurako Kawamoto, K. Fujimoto, H. Kawaguchi, J. Barton̆
The presence of N,N-dimethylacrylamide (NDA) influences the stability of initial, clear, single-phase Winsor IV inverse microemulsion composed of toluene/AOT (sodium salt of bis(2-ethylhexyl) sulfosuccinate)/NDA/water/acrylamide (AAm). For a molar fraction of NDA, nNDA = [NDA]/([NDA] + [AAm]) = 0.200 a single-phase system turned to a milky one during polymerization initiated by oil-soluble dibenzoyl peroxide or water-soluble ammonium peroxodisulfate, and finally a two-phase system was formed. For nNDA values greater than 0.200 also the precipitation of a polymeric product was observed during polymerization. The (co)polymerization rate of AAm and NDA exponentially decreases with increasing value of nNDA, while the reverse is true for the (co)polymer particle diameter. The results support the idea of simultaneously proceeding free-radical polymerization initiated by free radicals in continuous oil and dispersed water phase of the inverse microemulsion system. Die Gegenwart von N,N-Dimethylacrylamid (NDA) beeinflust die Stabilitat von klaren, einphasigen inversen Winsor-IV-Mikroemulsionen aus Toluol/AOT (Natriumsalz von Bis(2-ethylhexyl)sulfosuccinat)/NDA/Wasser/Acrylamid (AAm). Wahrend der durch lipophiles Benzoylperoxid oder hydrophiles Ammoniumperoxodisulfat initiierten Polymerisation wird das klare Ein-Phasen-System bei einem NDA-Molanteil von nNDA = [NDA]/([NDA] + [AAm]) = 0.200 milchig trub und bildet schlieslich ein Zwei-Phasen-System. Bei nNDA-Werten uber 0.200 fallt wahrend der Polymerisation auch eine polymere Substanz aus. Die (Co)Polymerisationsgeschwindigkeit von AAm und NDA nimmt exponentiell mit steigendem nNDA-Wert ab, wahrend der Durchmesser der (Co)Polymerteilchen wachst. Diese Ergebnisse stutzen die These einer simultan verlaufenden Radikalkettenpolymerisation, die durch freie Radikale in einer kontinuierlichen Ol- und einer dispergierten wasrigen Phase des inversen Mikroemulsionssystems initiiert wird.
N,N-二甲基丙烯酰胺(NDA)的存在影响了甲苯/二甲基丙烯酰胺(AOT)/NDA/水/丙烯酰胺(AAm)组成的初始、透明、单相Winsor IV逆微乳液的稳定性。当NDA的摩尔分数nNDA = [NDA]/([NDA] + [AAm]) = 0.200时,油溶性过氧化二苯甲酰或水溶性过氧二硫酸铵引发的聚合反应使单相体系变为乳状体系,最终形成两相体系。当nNDA值大于0.200时,还观察到聚合过程中聚合产物的沉淀。AAm和NDA的(co)聚合速率随nNDA值的增加呈指数降低,而(co)聚合物粒径则相反。研究结果支持了反相微乳液体系中连续油相和分散水相自由基同时引发自由基聚合的观点。dimethylacrylamid (NDA), dimethylacrylamid (AAm), degegenwart von N,N- dimethylacrylamid (NDA), dedestabilitat von klaren, dephasen inverse winor - iv - microemulsionen aus Toluol/AOT (Natriumsalz von Bis(2-乙基己基)磺基琥珀酸)/NDA/Wasser/丙烯酰胺(AAm))。亲脂剂苯甲酰过氧化物亲水剂氨过氧化物二硫脂引发剂的聚合反应:NDA- molanteil - nNDA = [NDA]/([NDA] + [AAm]) = 0.200;benda - werten在2000年的研究中发现了聚合聚合的新趋势。(1) dco (Co) polymerationsgeswindikeit on AAm和NDA最小指数。(2)dco (Co) polymerationsgeswindikeit on AAm和NDA最小指数。这两种微乳液体系分别是:verlaufenden、radikalketen、verlaufenden、verlaufinenden、verlaufinenden、verlaufinenden、verlaufinenden、veridecolen、veridecolen、veridecolen、veridecolen、veridecolen、veridecolen、veridecolen、veridecolen等。
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引用次数: 14
Hydrophilic PVC composite films obtained by in situ polymerization, 1 : Swelling studies 原位聚合法制备亲水性PVC复合膜,1:溶胀研究
Pub Date : 1998-06-01 DOI: 10.1002/(SICI)1522-9505(19980601)257:1<31::AID-APMC31>3.0.CO;2-#
C. Simionescu, Carmen Topor
In order to introduce a monomer into a PVC matrix, the swelling behavior of PVC films was tested in four solvents (acetone, methyl ethyl ketone, benzene, and toluene) and in acrylic acid solutions in acetone (10, 25 and 50 wt.-%) containing 0.1 wt.-% azoisobutyronitrile. The type of transport, diffusion and permeation coefficients, sorption kinetics and Arrhenius parameters are discussed.
为了将单体引入PVC基体,在四种溶剂(丙酮、甲基乙基酮、苯和甲苯)和含有0.1 wt.-%偶氮异丁腈的丙酮(10、25和50 wt.-%)的丙烯酸溶液中测试了PVC薄膜的膨胀行为。讨论了输运类型、扩散和渗透系数、吸附动力学和阿伦尼乌斯参数。
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引用次数: 1
New method for predicting lifetime of seals from compression-stress relaxation experiments 从压应力松弛试验中预测密封件寿命的新方法
Pub Date : 1998-06-01 DOI: 10.1002/(SICI)1522-9505(19981201)261-262:1<83::AID-APMC83>3.0.CO;2-#
K. Gillen, M. Keenan, J. Wise
Interpretation of compression stress-relaxation (CSR) experiments for elastomers in air is complicated by (1) the presence of both physical and chemical relaxation and (2) anomalous diffusion-limited oxidation (DLO) effects. For a butyl material, the authors first use shear relaxation data to indicate that physical relaxation effects are negligible during typical high temperature CSR experiments. They then show that experiments on standard CSR samples ({approximately}15 mm diameter when compressed) lead to complex non-Arrhenius behavior. By combining reaction kinetics based on the historic basic autoxidation scheme with a diffusion equation appropriate to disk-shaped samples, they derive a theoretical DLO model appropriate to CSR experiments. Using oxygen consumption and permeation rate measurements, the theory shows that important DLO effects are responsible for the observed non-Arrhenius behavior. To minimize DLO effects, they introduce a new CSR methodology based on the use of numerous small disk samples strained in parallel. Results from these parallel, minidisk experiments lead to Arrhenius behavior with an activation energy consistent with values commonly observed for elastomers, allowing more confident extrapolated predictions. In addition, excellent correlation is noted between the CSR force decay and the oxygen consumption rate, consistent with the expectation that oxidative scission processes dominate the CSR results.
空气中弹性体的压缩应力松弛(CSR)实验的解释由于(1)物理和化学松弛的存在以及(2)异常扩散限制氧化(DLO)效应而变得复杂。对于丁基材料,作者首先使用剪切松弛数据表明,在典型的高温CSR实验中,物理松弛效应可以忽略不计。他们随后表明,在标准CSR样品(压缩时直径约为15毫米)上进行的实验导致了复杂的非阿伦尼乌斯行为。通过将基于历史基本自氧化方案的反应动力学与适合于圆盘状样品的扩散方程相结合,他们推导出适合于CSR实验的理论DLO模型。利用耗氧量和渗透速率测量,该理论表明重要的DLO效应是观测到的非阿伦尼乌斯行为的原因。为了最小化DLO效应,他们引入了一种新的CSR方法,该方法基于并行使用许多小磁盘样本。这些平行的小圆盘实验的结果表明,阿伦尼乌斯行为的活化能与弹性体通常观察到的值一致,从而允许更有信心的外推预测。此外,CSR力衰减与耗氧速率之间存在良好的相关性,这与氧化裂解过程主导CSR结果的预期一致。
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引用次数: 16
期刊
Angewandte Makromolekulare Chemie
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