117 resultados para PP NANOCOMPOSITES
Resumo:
用WAXD、TBA、DSC等方法对PP/EPO共混体系的结晶结构和相容性进行了研究。WAXD方法测定表明PP/EPO共混体系的结晶度随EPO组份含量的增加而降低,晶胞参数值与组份比无关,使用Hosemann次晶模型法计算了此体系的第二类晶格畸变和应力畸变,表明衍射峰的宽化主要是由第二类晶格畸变引起的。根据DSC和TBA实验得出在所有组成PP/EPO共混体系是不相容的,但在非晶区可能部分相容。采用WAXD、DDV、DSC等方法对LDPE/EPO共混体系的结晶结构和相容性进行了研究,用Ruland方法计算的结晶度值随EPO组份含量的增加而降低,晶胞参数值与组份比无关。使用方差——范围函数方法计算了LDPE/EPO共混体系的(110)和(200)晶面的微晶大小(L_(hkL))和晶格畸变参数(g_t)。L_(hkL)和g_t值随EPO组份的增加而下降。从DDV-II粘弹谱仪测得的共混体系的谱图可看出,在β松驰附近,EPO的β转变随LDPE的加入量增加向低温方向移动,这是由于渗透到EPO非晶中的LDPE非晶部分影响了EPO链段运动所致。从LDPE/EPO共混体系的DSC图谱可知,只存在一个熔融峰,这说明很可能LDPE与EPO形成了共晶,从共混物的Tm、Tc可知,随EPO组份增加,熔点下降,结晶温度下降,纯EPO显示出高于LDPE及共混物的Tm.WAXD法证明,这是由于EPO中PE长序列贡献的结果。为了进一步证实EPO中少量结晶相与LDPE中晶相形成了共晶,我们做了萃取实验,结果表明了共晶的存在。由于各种聚乙烯的非晶相间是任意混容的,大部分为非晶部分的EPO中少量结晶相又与LDPE的结晶相形成了共晶,因盯LDPE/EPO是相容的共混体系。用DSC方法研究了LDPE/EPO共混体系的结晶动力学,对LDPE/EPO共混体系的等温结晶动力学研究表明,共混物是三维生长的异相成核。共混体系的平衡熔点随EPO含量的增加而降低,采用Lauritzen提出的Z判断方法,得出共混体系在各个结晶温度下的结晶过程都是以方式(II)进行的。采用Avrami方程和Ozawa方程的新的处理非等温结晶动力学的方程,研究了LDPE/EPO共混体系的非等温结晶动力学,得到了描述非等温结晶过程的一些基本参数。
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本工作旨在通过共聚、共混技术制备酚酞型聚芳醚砜共聚物(PP/BiS-T) PES和共混物(PPS/PES-C)、PPO/PES-C,以便改善酚酞型聚芳醚砜(PES-C)的加工性能(特别是注射加工性能)和耐溶剂性能。通过研究共聚物和共混物的微观结构,聚集态结构与性能的关系,探索改善酚酞型聚芳醚硕性能的有效途径第一部分:(PP/BiS-T) PES共聚物的合成、结构与性能(PP/BiS-T) PES共聚物是以4,4'二氯二苯砜(DCDPS)、酚酞(PP)和4,4'-二羟基二苯硫醚(BiS-T)为单体,采用固体无水K_2CO_3/NMP/TMSO_2 混合溶剂反应体系合成的。共聚反应规律研究表明:在NMP/TMSO_2混合溶剂中,共聚反应可以顺利进行,避免了交联反应的发生,并成功地合成了高分子量的(PP/BiS-T) PES共聚物。DSC分析结果表明(PP/BiS-T) PES系列属于无定形的均相共聚物体系,每一组成比例对应的共聚物只具有一个玻璃化转变温度。且随组成比例的改变呈线性变化,TBA分析结果与DSC基本一致,并证实了(PP/BiS-T) PES属于均相共聚物体系,而不是均聚物的共混物。TG分析表明:共聚物具有良好的耐热氧化稳定性BiS-T链节在分子链中起到了提高自身抗氧性的作用。1R光谱对共聚物的结构进行表征。~(13)C-NMR分析确认共聚物多属于无规共聚物。动态力学试验表明共聚物(PP/BiS-T) PES以及PES-C,在-100 ℃附近和0-100 ℃,存在着次级松驰与转变,并发现水分子的存在对这种转变(次级松驰)有一定的影响。共聚物的熔融流动性试验和溶解性试验表明共聚物(PP/BiS-T) PES具有稍好于PES-C的熔融流动性;溶解性与PES-C类似。力学试验说明共聚物属于强而硬类型的聚合物。第二部分:PPS/PES-C共混物的制备、聚集态结构与性能PPS/PES-C共混物是以联苯/二苯硕混合物为溶剂,采用溶液沉析方法制备的,DSC、WAXD,SEM和1R分析手段对共混物的聚集态结构和微观结构进行了表征。DSC分析认为共混物属于多相体系,PPS的结晶性随着PES-C含量增加而降低。DSC和SEM观察结果表明:相转变发生在PPS占40%左右。PPS占25%时,DSC曲线呈现出界面相玻璃化转变温度。共混物具有良好的耐热氧化稳定性和耐热分解稳定性。微晶大小计算结果:PES-C存在导致了PPS微晶大小降低。WAXD曲线表明PPS占50%,共混物中的PPS具有较好的结晶性。SEM观察发现:随着PES-C含量增加,PES-C由分散相(PES-C50%)变为连续相(PES-C70%)。PPS占50%或低于50%时,共混物体系不仅发生了微观相分离,而且发生了宏观相分离。M.I.指数表明共混物中PPS为连续相时,共混物具有良好的熔融流动性。溶解性试验结果:共混物具有较好的耐溶剂性。第三部分:PPO/PES-C共混物的合成、结构与性能 PPO/PES-C共混物系用溶液-涂膜法,以氯彷为溶剂制备的。讨论了由同一共混物溶液浓度下制备的共混物的互溶性随组成的改变而变化。DSC分析结果:PPO/PES-C属于部分相溶性体系。利用Fox方程推导式计算结果表明PPO在富PES-C相中具有良好的分散性;而PES-C在富PPO相中的分散性较差。共混物(PPO/PES-C)试样经丙酮浸泡后,PPO(>50%)发生了溶剂诱导结晶现象,同时丙酮促使共混物发生完全相分离。结晶溶化热显示共混物中少量的PES-C存在有利于PPO的溶剂诱导结晶。TG分析表明共混物具有良好的耐热分解稳定性和耐热氧化分解稳定性。偏光显微镜下观察到PPO球晶的存在。SEM和FT-1R分别对共混物的形态结构和微观结构进行了表征。WAXD试验证实了丙酮处理的(PPO/PES-C)(70/30),(90/10)共混物中PPO的结晶性。溶解性试验表明:PPO掺入有助于 PES-C的耐溶剂性提高。
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本文的主要工作如下:1、本文提出用化学方法将聚丙烯(PP)接枝马来酸酐(MA)的方法,得到了较高接枝率的PP-MA接枝物,MA的接枝状态主要取决于反应条件。2.本文合成了(PP-MA)-g-PEO梳型接枝物,接枝物中PP、PEO结晶性能明显与纯PP、PEO不同。3.采用溶液共混方法制备了PP/PMMA、PP/TPU、PP/PA-12、PP/PEO四种共混物。从实验上证明了PP-MA及(PP-MA)-g-MA两种接枝物对上述四种共混物增容的机理。4.共混物中极性聚合物对PP结晶具有两种不同作用:成核促进作用和结晶阻碍作用。5.在PP/PA-12、PP/PEO这类双晶共混体系中,组分之间相互作用比较复杂,尤其是高熔点组分对低熔点组分的影响,如取向附生作用。6.结晶分极是含有结晶组分不相容共混物的普遍具有的现象,它与组分配比、异种聚合物成核能力及组分之间相容性有必然联系。7、PP-MA是PP/TPU、PP/NBR-26有效增容剂,开发上述两种共混物材料势在必行。
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The pp -> pn pi(+) reaction is a channel with the largest total cross section for pp collision in COSY/CSR energy region. In this work, we investigate individual contributions from various N* and Delta* resonances with mass up to about 2 GeV for the pp -> pn pi(+) reaction. We extend a resonance model, which can reproduce the observed total cross section quite well, to give theoretical predictions of various differential cross sections for the present reaction at T-p = 2.88 GeV. It could serve as a reference for identifying new physics in the future experiments at HIRFL-CSR.
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In an effective Lagrangian model we find that the N*(1535) resonance contribution might be important to the interpretation of the present data of the pp -> pp eta' and pn -> d phi reactions. The strong coupling strength of N*(1.535) to eta' and phi are indicated, and the possible implication to the intrinsic component of N*(1535) is explored. These results may provide hints to the real origin of the OZI rule violation. It is stressed that further measurements could be performed at the Cooling Storage Ring (CSR) at Lanzhou of China.
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We explore production mechanism and final state interaction in the pp -> nK(+)Sigma(+) channel based on the inconsistent experimental data published respectively by COSY-11 and COSY-ANKE. The scattering parameter a > 0 for n Sigma(+) interaction is favoured by large near-threshold cross section within a nonrelativistic parametrization investigation, and a strong n Sigma(+) interaction comparable to pp interaction is also indicated. Based on this analysis we calculate the contribution from resonance Delta*(1920) through pi(+) exchange within resonance model, and the numerical result suggests a rather small near-threshold total cross section, which is consistent with the COSY-ANKE data. With an additional sub-threshold resonance Delta*(1620), the model gives a much better description to the rather large near-threshold total cross section published by COSY-11
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In this paper, we report for the first time on the synthesis of ZnO nanocrystallites in conjugated polymer (PPV) nanofibers by the coupling of the in situ/blend methods and electrospinning. These composite nanofibers were characterized by fluorescence microscopy, atomic force microscope (AFM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffraction (XRD).
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In this paper, the modification of polypropylene (PP) with acrylic acid (AA) by reactive extrusion using pre-irradiated PP (rPP) as initiator was investigated. It was found the relatively high graft degree (Gd) and slight degradation of modified PP was obtained when 20 wt% rPP was used. This result can be explained in terms of effective concentration of free radicals.
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用DSC方法研究了聚丙烯(PP)、PP与间同1,2-聚丁二烯(s-1,2PB)共混物的非等温结晶行为,结果表明:Mo法处理PP及PP侮1,2PB(90/10)共混物是非常适宜的,而用Ozawa法处理则存在缺陷。用Jeziomy法处理共混物也是适宜的,但对PP处理存在缺陷;s-1,2PB对PP有加速结晶的作用;s-1,2PB使PP的结晶活化能降低,s-1,2PB在PP结晶过程中起到异相成核的作用
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In order to solidify the electrochemiluminescence (ECL) luminophor tris(2,2'-bipyridyl) ruthenium(II) ([Ru(bpy)(3)](2+)) onto the electrode surfaces robustly, the negative charged heteropolyacids (HPAs) moieties were utilized to attract and bond cations [Ru(bpy)(3)](2+) via an adsorption method. The compositions and microstructures of the hybrid complexes were characterized by elemental analysis (EDS), spectroscopic techniques (UV-vis, FTIR) and field-emission scanning electron microscopy (FE-SEM). The electrochemical and ECL behaviors of the [Ru(bpy)(3)](2+)/[PW12O40](3-) hybrid complex contained in the solid film of the nanocomposites formed on the electrode surfaces were also studied.
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By reducing the attraction between the platelets of octaclecylammonium chloride modified montmorillonite (OMMT-C18) via pre-intercalation of maleated polypropylene (MAPP), OMMT-C18 was exfoliated in thermoplastic polyurethane (TPU) matrix during melt-mixing. Wide angle X-ray diffraction, transmission electron microscopy and thermogravimetric analysis were used to investigate the microstructure of TPU nanocomposites. Three factors (including introducing sequence, the kind and the content of MAPP) showed important effects on the dispersion degree of OMMT-C18 in TPU matrix. The results confirmed that the pre-intercalation of MAPP was necessary for the exfoliation of OMMT-C18; however, the role of MAPP in TPU nanocomposites was different from that in polypropylene nanocomposites.
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The effect of combination between a trace of halogenated compounds (such as ferric chloride and ammonium bromide) and Ni2O3 particles on the carbonization of polypropylene (PP) was investigated during combustion. The results showed a synergistic catalysis of combined halogenated compounds with Ni2O3 in promoting the formation of the residual char during combustion. The investigation on the promotion mechanism showed that halide radical releasing from halogen-containing additives worked as a catalyst to accelerate dehydrogenation-aromatization of degradation products of PR which promote the degradation products to form the residual char catalyzed by nickel catalyst.
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Deformation behavior of polyethylene/modified montmorillonites with polymerizable surfactant (PE/P-MMT) nanocomposite with strong interfacial interaction was studied by means of morphology observation and X-ray scattering measurements. The orientation of PE chains was accompanied by the orientation of well-dispersed MMT platelets due to the presence of strong interfacial interaction, and both of the orientations were parallel to the deformation direction. The high degree of orientation of MMT platelets and PE chains resulted from the synergistic movement of PE matrix and MMTs, which originated from the presence of a network-like structure.
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A one-step method was developed to fabricate conductive graphene/SnO2 (GS) nanocomposites in acidic solution. Graphite oxides were reduced by SnCl2 to graphene sheets in the presence of HCl and urea. The reducing process was accompanied by generation of SnO2 nanoparticles. The structure and composition of GS nanocomposites were confirmed by means of transmission electron microscopy, x-ray photoelectron and Raman spectroscopy. Moreover, the ultracapacitor characteristics of GS nanocomposites were studied by cyclic voltammograms (CVs) and electrical impedance spectroscopy (EIS). The CVs of GS nanocomposites are nearly rectangular in shape and the specific capacitance degrades slightly as the voltage scan rate is increased. The EIS of GS nanocomposites presents a phase angle close to p/2 at low frequency, indicating a good capacitive behavior.