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采用溶液浇铸法制备了不同组分比的聚甲基丙烯酸甲酯(PMMA)/苯乙烯–丙烯腈无规共聚物(SAN)共混物。通过光学显微镜,考察了不同粒径的SiO2粒子对PMMA/SAN非临界组成共混物相行为的影响。结果表明,SiO2粒子的加入会抑制PMMA/SAN共混物相形态的发展,这种抑制作用在填料粒径越小时表现越明显。此外,SiO2粒子对PMMA/SAN共混物相分离动力学的影响具有组分依赖性,当PMMA为少数相时,粒子对PMMA/SAN共混物相分离动力学的抑制作用更为明显。该现象可能是由于SiO2粒子的选择性吸附限制了PMMA分子链的运动,从而导致PMMA为少数相的PMMA/SAN体系的黏弹性增加更大。 相似文献
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通过种子乳液聚合方法合成聚丁二烯接枝甲基丙烯酸甲酯(PB-g-MMA)核-壳改性剂。将PB-g-MMA、聚氯乙烯(PVC)和聚甲基丙烯酸甲酯(PMMA)在160℃下熔融共混,制得橡胶含量为16%(质量含量)的一系列的橡胶改性PVC/PMMA共混物。研究了基体组成对共混物力学性能和形态结构的影响。结果表明在宽组成范围内PVC和PMMA是相容的,并且当PVC含量较少时,共混物以脆性方式断裂,银纹是其主要的形变机理;当PVC含量较多时,共混物以韧性方式断裂,此时主要的形变机理是橡胶粒子的空洞化和基体的剪切屈服。在橡胶改性PVC/PMMA共混物中,随着基体组成的改变形变,机理存在着从银纹到剪切屈服的转变。 相似文献
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通过在线测定聚合反应体系黏度,取样分析相差图片中聚合物形貌、橡胶粒径,产品的TEM表征结果以及测试产品的物理力学性能等,考察了本体ABS聚合过程中,橡胶相和SAN基质相的相态变化过程、橡胶粒子的形成过程以及橡胶相态结构对物理力学性能的影响。结果表明:随着聚合反应的进行,反应体系黏度不断升高,经历两相转变时体系黏度急剧下降,而后逐渐升高;相转变后橡胶粒子经历从大到小的形成过程并逐步稳定,最终以包藏结构存在于ABS产品中,这种包藏结构能显著提高ABS产品的韧性,缺口冲击强度提高20%,断裂伸长率提高2倍以上。 相似文献
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研究了复合橡胶对高抗冲聚苯乙烯(HIPS)结构与性能的影响,并用透射电子显微镜对HIPS进行了表征。结果表明:低顺聚丁二烯橡胶(简称低顺橡胶)能增加HIPS橡胶相体积分数,使橡胶粒子形态分布更均匀;高顺聚丁二烯橡胶(简称高顺橡胶)有利于提高产品的韧性;低顺橡胶对HIPS弯曲强度和拉伸强度的增加贡献更大;采用高顺橡胶与低顺橡胶复合,能够协调HIPS的韧性、弯曲强度和拉伸强度。 相似文献
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通过乳液聚合制备了橡胶粒子尺寸为64~420 nm的丙烯腈-丁二烯-苯乙烯(ABS)共聚物.然后将其与SAN-T树脂熔融共混制备橡胶质量分数为15%的ABS树脂.研究了橡胶粒子尺寸对ABS树脂力学性能影响和材料内部形态结构.结果表明:随着橡胶粒子尺寸的增加ABS树脂的冲击韧性提高.当橡胶粒子尺寸在320 nm时,拉伸强度达到最大,ABS树脂的综合性能达到最好.粒子尺寸在64~110 nm时,橡胶粒子在基体内部发生团聚,材料发生脆性断裂.当橡胶粒子尺寸在216~420 nm时,材料主要以韧性断裂为主,发生脆韧转变.具有双峰分布ABS-110nm/ABS-275 nm共混物大、小橡胶粒子间发生明显的协同作用. 相似文献
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In the absence of emulsifier, we prepared stable emulsifier‐free polymethylmethacrylate/polystyrene (PMMA/PSt) copolymer latex by batch method with comonomer N,N‐dimethyl, N‐butyl, N‐methacryloloxylethyl ammonium bromide (DBMEA) by using A1BN as initiator. The size distribution of the latex particles was very narrow and the copolymer particles were spherical and very uniform. Under the same recipe and polymerization conditions, PMMA/PSt and PSt/PMMA composite polymer particle latices were prepared by a semicontinuous emulsifier‐free seeded emulsion polymerization method. The sizes and size distributions of composite latex particles were determined both by quasi‐elastic light scattering and transmission electron microscopy (TEM). The effects of feeding manner and staining agents on the morphologies of the composite particles were studied. The results were as follows: the latex particles were dyed with pH 2.0 phosphotungestic acid solution and with uranyl acetate solution, respectively, revealing that the morphologies of the composite latex particles were obviously core–shell structures. The core–shell polymer structure of PMMA/PSt was also studied by 1H, 13C, 2D NMR, and distortionless enhancement by polarization transfer, or DEPT, spectroscopy. Results showed that PMMA/PSt polymers are composed of PSt homopolymer, PMMA homopolymer, and PMMA‐g‐PSt graft copolymers; results by NMR are consistent with TEM results. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1681–1687, 2005 相似文献
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Prapasri Rajatapiti Victoria L. Dimonie Mohamed S. El-Aasser Menas S. Vratsanos 《应用聚合物科学杂志》1997,63(2):205-219
Graft copolymers with poly(n-butyl acrylate) (PBA) backbones and poly(methyl methacrylate) (PMMA) macromonomer side chains are used as compatibilizing agents for PBA/PMMA composite latexes. The composite latexes are prepared by seeded emulsion polymerization of methyl methacrylate (MMA) in the presence of PBA particles. Graft copolymers were already incorporated into the PBA particles prior to using these particles as seed via miniemulsion (co)polymerization of n-butyl acrylate (BA) in the presence of the macromonomers. Comparison between size averages of composite and seed particles indicates no secondary nucleation of MMA during seeded emulsion polymerization. Transmission electron microscopy (TEM) observations of composite particles show the dependence of particle morphologies with the amount of macromonomer (i.e., mole ratio of macromonomer to BA and molecular weight of macromonomer) in seed latex. The more uniform coverage with the higher amount of macromonomer suggests that graft copolymers decrease the interfacial tension between core and shell layers in the composite particles. Dynamic mechanical analysis of composite latex films indicates the existence of an interphase region between PBA and PMMA. The dynamic mechanical properties of these films are related to the morphology of the composite particles, the arrangement of phases in the films, and the volume of the interphase polymer. © 1997 John Wiley & Sons, Inc. 相似文献
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通过种子乳液聚合方法,采用丙烯酸丁酯(BA)、丙烯酸2-乙基己酯(EHA)为核层单体,与少量有机锡单体共聚制备了含有机锡的P(BA-EHA)胶乳,与氯乙烯(VC)乳液接枝共聚合成了P(BA-EHA)/PVC复合改性剂。通过透射电子显微镜(TEM)、动态力学分析仪(DMA)、扫描电子显微镜(SEM)等测试手段,考察了复合乳胶粒子和共混材料的形态结构、复合改性剂中有机锡含量对其共混改性PVC材料的力学性能及复合粒子热稳定性的影响。DMA和TEM分析结果表明:复合粒子的加入显著改善了橡胶相与PVC之间的相容性,P(BA-EHA)在PVC基体中具有很好的分散性和均匀度,SEM照片显示共混材料缺口断面表现为优异的基体屈服型断裂韧性。 相似文献
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采用原位乳液聚合法制备了聚甲基丙烯酸甲酯(PMMA)/三聚氰胺氰尿酸盐(MC)复合胶粒,对其进行X光电子能谱及热重分析结果显示,在MC阻燃剂颗粒表面覆盖了一层PMMA胶膜,形成了具有核-壳结构的PMMA/MC复合胶粒;MC能影响PMMA的热降解过程并促进其成炭;在尼龙6(PA6)中的应用结果表明,PMMA/MC复合胶粒能改善PA6的力学性能和阻燃性能。 相似文献
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Poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core–shell particles embedded with nanometer‐sized silica particles were prepared by emulsion polymerization of butyl acrylate (BA) in the presence of silica particles preabsorbed with 2,2′‐azobis(2‐amidinopropane)dihydrochloride (AIBA) initiator and subsequent MMA emulsion polymerization in the presence of PBA/silica composite particles. The morphologies of the resulting PBA/silica and PBA/silica/PMMA composite particles were characterized, which showed that AIBA could be absorbed effectively onto silica particles when the pH of the dispersion medium was greater than the isoelectric potential point of silica. The critical amount of AIBA added to have stable dispersion of silica particles increased as the pH of the dispersion medium increased. PBA/silica composite particles prepared by in situ emulsion polymerization using silica preabsorbed with AIBA showed higher silica absorption efficiency than did the PBA/silica composite particles prepared by direct mixing of PBA latex and silica dispersion or by emulsion polymerization in which AIBA was added after the mixing of BA and silica. The PBA/silica composite particles exhibited a raspberrylike morphology, with silica particles “adhered” to the surfaces of the PBA particles, whereas the PBA/silica/PMMA composite latex particles exhibited a sandwich morphology, with silica particles mainly at the interface between the PBA core and the PMMA shell. Subsequently, the PBA/silica/PMMA composite latex obtained had a narrow particle size distribution and good dispersion stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3425–3432, 2006 相似文献
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The radical-induced grafting of n-butyl acrylate (BA) onto poly(butadiene-co-styrene) [(P(Bd-S)] latexes during seeded emulsion polymerization was studied. This P(Bd-S)/PBA rubber/rubber core/shell latex system exhibited unique grafting behavior as compared to other extensively studied rubber/glass core/shell latex systems, such as poly(butadiene-co-styrene)/poly(methyl methacrylate) [P(Bd-S)/PMMA], poly(butadiene-co-styrene)/polystyrene [P(Bd-S)/PS] and poly(butadiene-co-styrene)/poly(acrylonitrile)[P(Bd-S)/PAN]. These composite latexes were characterized by the formation of a highly grafted/crosslinked P(Bd-S)/PBA interphase zone generated during the seeded emulsion polymerization process. Although both of the individual core and shell polymers studied were “soft” themselves, the resulting P(Bd-S)/PBA composite latex particles were found to be rather “hard.” The formation of the interphase zone was studied by using techniques such as solvent extraction, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:511–523, 1997 相似文献
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Wenping Chen Meifang Zhu Song Song Bin Sun Yanmo Chen Hans‐Jürgen P. Adler 《大分子材料与工程》2005,290(7):669-674
Summary: It is necessary to use a selective staining agent to enhance image contrast for transmission electron microscopy (TEM) morphological characterization of polymer composite particles. However, the typical selective staining agents osmium tetraoxide and ruthenium tetraoxide are neither suitable for poly(methyl methacrylate) (PMMA)/polyacrylonitrile (PAN) composite particles. In this study, it was found that phosphotungstic acid (PTA) solution with 6.4 pH value is unsuitable for PMMA, but it can stain PAN. Therefore, it can be a selective staining agent in the TEM for PMMA/PAN composite particles. By controlling different thermodynamic and kinetic polymerization parameters, PMMA/PAN and PMMA/P(AN‐MMA) composite particles with nano to submicro sizes having different morphological structures were synthesized. TEM micrographs of all these composite particles with their predicted morphology have been compared, and the experimental results are completely consistent with the predictions.
TEM micrograph of PMMA/PAN composite particles. 相似文献
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无机粒子的有机高分子化及其对PVC填充改性的研究 总被引:5,自引:0,他引:5
本文研究了几种无机 有机复合粒子与聚氯乙烯共混复合材料力学性能的变化规律。结果表明 :SiO2 /HPMC PMMA(SiO2 经SDS预处理 )和HPMC g PMMA使材料力学性能下降 ,而SiO2 /HPMC PMMA(未经SDS处理 )、TiO2 /HPMC PMMA、ZnO/HPMC PMMA复合粒子使材料的力学性能有所提高。经柔性设计后的SiO2 /HPMC PBA/PMMA和ZnO/HPMC PBA/PMMA使材料的冲击强度提高的幅度更大。SEM提供的证据也表明 :ZnO复合粒子使材料出现较好的塑性变形 ;经柔性设计的SiO2 复合粒子比未经柔性设计的SiO2 复合粒子使材料的塑性变形也更加显著 相似文献