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1.
用硅溶胶、丙烯酸酯类单体,以过硫酸钾为引发剂,配以适当的乳化剂,采用乳液聚合法制成了高SiO2含量硅溶胶-聚丙烯酸酯复合乳液。系统的研究了温度、乳化剂种类及用量、单体SiO2质量比等因素对乳液稳定性的影响。结果表明:75℃为最佳反应温度;十二烷基硫酸钠(SDS)为最佳乳化剂;当SDS质量分数为0.45%~0.7%、单体SiO2质量比为3时,可制得SiO2质量分数为10%的复合乳液,且乳液的稳定性达到使用要求,此法制得的复合乳液的涂膜水白性较共混改性乳液(硅溶胶和纯丙乳液)和纯丙乳液的涂膜有显著的提高;TEM图片显示,复合乳液中,硅溶胶粒子是以纳米SiO2粒子存在的,且在复合乳液中比在共混改性乳液(硅溶胶和纯丙乳液)中分散的更均匀。 相似文献
2.
有机硅-丙烯酸酯共聚乳液的制备和性能研究 总被引:8,自引:0,他引:8
用γ-甲基丙烯酰氧丙基三甲氧基硅烷(MATS)与丙烯酸酯类单体进行乳液共聚,制备了有机硅丙烯酸酯共聚乳液.考察了聚合方法和有机硅单体含量对聚合过程稳定性的影响,详细讨论了有机硅单体用量对乳液粒径大小和粘度的影响,采用PCS跟踪了聚合过程的粒径大小,并对粒子形态采用TEM进行了表征.实验表明.采用种子乳液法时,乳液的聚合稳定性良好.聚合过程中乳胶粒径逐步增加.随MATS用量的增加.乳液的聚合稳定性变差,乳胶粒的平均粒径增加,乳液的粘度增大.乳胶粒子呈球形,粒径分布较窄。 相似文献
3.
离子交换膜燃料电池作为一种理想的氢能发电装置,是目前氢能研究开发的热点。用实验方法研究了电极添加剂Nafion乳液对离子交换膜燃料电池电化学性能的影响。实验结果表明,在电极中加入适量的Nafion乳液可以显著地提高电极的电催化反应活性。当电极中Nafion乳液的含量为3% ̄5%时,燃料电池的放电电压和电流密度者处于高峰值状态。实验结果还发现,用不同方法配制的Nafion乳液对燃料电池放电性能的影响 相似文献
4.
以丁氧基甲基丙烯酰胺(BOA)为活性单体,采用种子乳液聚合方法制备了PSt/P(BA-BOA)〔聚苯乙烯/聚(丙烯酸丁酯-丁氧基甲基丙烯酰胺)〕核壳型复合乳液.用透射电子显微镜观察了乳液粒子的微观状态,采用粒度分析仪测定了乳液粒子的粒径及其分布,对乳液的流变性能进行了测试.考察了聚合方式、乳化剂用量对乳液性能的影响 相似文献
5.
采用半连续乳液聚合方法制备了一种室温自交联合氟乳液,对影响含氟乳液涂膜性能的因素如N-MA含量(质量分数,下同)、成膜温度、含氟单体的用量及涂膜厚度等进行了分析.采用DSC法对乳液涂膜的玻璃化温度进行了测定,用Wilhelmy方法对膜的表面性能进行了表征,并通过人工加速老化实验来考察膜的耐老化性能.结果表明,所制得的乳液的性价比优于市场上的含氟乳液。 相似文献
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7.
聚丙烯酸酯/TiO2纳米复合乳液的研究 总被引:5,自引:0,他引:5
以丙烯酸酯为原料、纳米TiO2粉体或浆料作为改性剂,采用不同改性工艺,制备丙烯酸酯/TiO2纳米复舍乳液,研究各种因素(反应温度、原料组成、配比和其它添加剂)对乳液性能的影响。结果表明:以油酸作为纳米粉体TiO2的表面改性剂,可明显改善复合乳液的各种性能;各种改性方法中,表面改性效果最佳;表面改性剂(油酸)的用量为(0.15—0.25)%时,复合乳液及其涂膜的性能最佳;表面改性的纳米粉体TiO2对复合乳液的改性效果优于直接用纳米浆料混合所得的纳米复合乳液。 相似文献
8.
分别采用丙烯酸丁酯和苯乙烯作为软硬单体,NP和DBS的混合乳化剂作为乳化体系,采用过硫酸钾作为引发剂,并引入功能性单体甲基丙烯酸,用半连续种子乳液聚合工艺来制备苯丙乳液.在聚合过程中改变加入的乳化剂量.研究了乳化剂对苯丙乳液的平均粒径、稳定性、吸水率、粘度和流变性等性质的影响.研究结果表明随着乳化剂用量的增大,乳液胶粒的平均粒径减小,而乳液的粘度和胶膜的吸水率却增大.乳液的稳定性受乳化剂中非离子乳化剂和阴离子乳化剂的质量配比影响较大,而乳液的流变性则与乳化剂的浓度无关.并对乳化剂对乳液性质的影响原因进行解释和分析.因此,在制备不同用途的苯丙乳液时,必须要严格控制乳化剂的浓度及配比. 相似文献
9.
以丁氧基甲基丙烯酰胺为活性单体,采用种子乳液聚合方向制备了PSt/P(BA-BOA)「聚苯乙烯/取(丙烯酸丁酯-丁氧基甲基丙烯酰胺)」核索型复合乳液。用透射电子显微镜观察了乳液粒子的微观状态,采用粒度分析仪测定了乳液粒子的粒径及其分布,对乳液的流变性能进行了测试。 相似文献
10.
加料方法的不同对阴离子型聚氨酯乳液性能的影响 总被引:3,自引:0,他引:3
加料方法的不同直接影响到合成产物的结构,从而决定其产物具有不同的性质,用一步预聚体法和二步预聚体法合成了阴离子型聚氨酯乳液并研究其乳液粒径及乳胶膜的耐水性和力学性能方面的差异,研究结果表明二步预聚体法合成的乳液粒径较小,且其成膜物的耐水性及抗张强度,断裂伸长率者优于一步预聚体法合成的乳液。 相似文献
11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness. 相似文献
12.
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly. 相似文献
13.
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well. 相似文献
14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation. 相似文献
15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。 相似文献
16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death. 相似文献
17.
Miao Maosheng 《华南师范大学学报(自然科学版)》2014,(6)
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula- 相似文献
18.
Yang Weitao 《华南师范大学学报(自然科学版)》2014,46(6):137-138
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re- 相似文献
19.
Bernard Kirtman 《华南师范大学学报(自然科学版)》2014,(6)
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that 相似文献
20.
《上海师范大学学报(自然科学版)》2014,(5):550
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with 相似文献