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1.
The miniemulsion and macroemulsion polymerization of vinyl acetate with vinyl versatate in batch and semibatch systems was investigated. Vinyl versatate was added either as an emulsion with the vinyl acetate, or as a neat liquid stream. In the batch runs, there is a poor dispersion of vinyl versatate during the nucleation period for the runs in which the vinyl versatate was added neat at the beginning of the polymerization. This led to smaller particles, lower polymerization rate, and different polymer composition evolution when compared with runs in which the vinyl versatate was emulsified with the vinyl acetate. In seeded semibatch runs, residual surfactant in the seed latex, along with the propensity for homogeneous nucleation in vinyl acetate emulsions, resulted in continuing nucleation during the entire semibatch interval. The polymerization rate was primarily affected by monomer feed rate rather than the feeding mode. The effect of monomer feeding mode on copolymer composition was weak when the semibatch feed rate was low, indicating some level of vinyl versatate mass transfer resistance. In all runs, only one glass transition temperature was observed, indicating effective copolymerization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2219–2229, 2002 相似文献
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Pressure‐sensitive adhesives (PSAs) were produced with latexes synthesized via starved semibatch emulsion polymerization processes with butyl acrylate, three different kinds of hard monomers [styrene (St), methyl methacrylate, and 2‐phenoxy ethyl methacrylate (SR340)], acrylic acid, and 2‐hydroxy ethyl acrylate. The management of both the copolymer composition and the polymerization process allowed us to control the behavior of the PSAs. For the acrylate latexes, the types of hard monomers and their contents, the concentration of buffer [bicarbonate (NaHCO3)], and three kinds of semibatch processes were manipulated to modify the polymer properties. The performance of the PSA films cast from these latexes was evaluated by the peel strength. The results show that the PSA prepared with St exhibited the highest peel strength among the three hard monomers, and the latex synthesized by SR340 showed the largest gel content compared with the other two hard monomers. With increasing buffer, the latex particle size increased, and the peel strength initially increased to a maximum and then decreased. Nevertheless, the stability of the latexes decreased with increasing buffer concentration. In addition, the effects of the three kinds of semibatch processes on the peel strength of the PSA were also evaluated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40095. 相似文献
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The emulsion polymerization of the monomers methyl methacrylate (MMA) and 2‐ethylhexyl acrylate (EHA) was studied to investigate the effect of the crosslinkable monomer poly(propylene glycol diacrylate) (PPGDA). IR spectroscopy, NMR, differential scanning calorimetry, gel permeation chromatography, and scanning electron microscopy were used to characterize the synthesized polymers. These polymers were coated on glass panels and cured at appropriate temperatures to study the physical properties, swelling behavior, surface tension, and contact angle of these polymer latices. The results show that as the concentration of EHA monomer increased, the surface tension of the latices decreased. The copolymers were characterized by 1H‐NMR spectroscopy to ensure the absence of unreacted monomer, and the results confirm the incorporation of EHA units in the copolymer. The contact angle of the latices on the glass substrate was smaller than that on the metal. The swelling mechanism of the film showed that the Fickian diffusion coefficient with 10 wt % PPGDA was at a minimum value and was the most highly crosslinked polymer among the samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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Jana Machotová Lucie Zárybnická Radka Bačovská Eva Černošková 《Polymer-Plastics Technology and Engineering》2016,55(4):423-431
In this study, the spinnability of styrene–ethyl acrylate copolymers prepared via emulsion polymerization was explored with the aim to establish the influence of glass transition temperature and polymer composition on morphological features of electrospun materials with regard to their hydrophobic/hydrophilic nature. Nonwoven mats from polymer solutions in N,N′-dimethylformamide were spun using the electrospinning method (Nanospider? device). It was demonstrated that changing the copolymer polarity and glass transition temperature by copolymer composition or utilizing different supporting materials might lead to nanofiber webs with controlled hydrophobic/hydrophilic properties, which predetermines them for a wide range of applications such as protective textiles, composites, etc. 相似文献
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The kinetics of emulsion polymerization of monomers MMA/BA was studied to investigate the effect of cross‐linkable monomer PPGDA. The results showed that by the incorporation of PPGDA, rate constant of reaction decreased. The IR and differential scanning calorimetry were used to characterize the presence of PPGDA in the synthesized polymers. These polymers were coated on glass panels and cured at appropriate temperature. The results showed that the polymer containing 15 wt % PPGDA had minimum value of Fickian diffusion coefficient, thus showing highest level of cross‐linking among all the polymers studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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The target of the research is to examine influence of a polymerization process and monomer ratio on structures and compositions of phases in an emulsion copolymerization of n‐butyl acrylate (BA) and methyl methacrylate (MMA). Emulsion copolymerizations are performed using three different BA/MMA weight ratios (60%/40%, 50%/50%, and 40%/60%) and two different processes, statistical batch and seeded emulsion polymerizations. Phase structures, monomer compositions, and morphological stabilities of copolymers are investigated by differential scanning calorimetry, 1H‐NMR, and scanning electron microscopy. Gel permeation chromatography is used to follow the changes in the molar mass distribution during syntheses. The gel content and backbiting level of end products are measured by extraction and 13C‐NMR, respectively. Copolymerizations give products with a bimodal molar mass distribution and three or two separate phases having different BA/MMA compositions. The morphological stability of particles decreases with the increasing BA fraction in the feed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41467. 相似文献
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In order to investigate the influence of mixing flow condition on particle generation, poly(lactic acid) (PLA) particles were fabricated at different mixing velocities (10–50 m s?1) using a nanomixer through either the nanoprecipitation or the emulsion diffusion method. With a nanomixer (Couette–Taylor mixing geometry modified with cavitations), particles became smaller as the mixing velocity increased as long as the temperature was kept below the glass transition temperature (Tg) of PLA. Even in the emulsion diffusion method, it led to the formation of PLA nanoparticles in a short emulsification time (～1 min) and the mean diameter was less than 100 nm with deviation less than 10% (100 nm ± 10%). However, at high mixing velocity, the particle size was rapidly increased which was enhanced as mixing time increased. Dissipation rapidly increased the temperature inside the mixer above Tg of PLA, which caused smaller particles to agglomerate to form larger micron‐sized particles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46199. 相似文献
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采用乳液聚合的方法合成了一系列α-甲基苯乙烯(α-MSt)/苯乙烯(St)/丙烯腈(AN) (α-MSAN)共聚物,用ABS接枝共聚物与α-MSAN熔融共混制备了耐热ABS。研究了α-MSAN组成对ABS耐热性能及力学性能的影响。固定AN的含量,调整α-MSt/St配比,差示扫描量热分析发现,α-MSAN的玻璃化转变温度(Tg)随着α-MSt含量的增加呈线性增加趋势,α-MSt含量每增加10%,共聚物的Tg均提高约1-2℃;动态力学分析发现,ABS树脂的Tg随着α-MS含量的增加向高温方向移动,当α-MSt/St配比为100/0时Tg高达129. 5 C。固定α-MSt/St的配比为50/50,调整AN含量,结果发现,当AN含量为25%(质量分数,下同)时,ABS树脂的Tg可达121℃,且力学性能最佳。 相似文献
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耐热ABS树脂的制备 总被引：2，自引：0，他引：2
采用乳液聚合法合成了一系列N-苯基马来酰亚胺（NPMI）-苯乙烯（St）-丙烯腈（AN）共聚物（简称SMIA树脂）,将其与AN-丁二烯-St三元共聚物（ABS）熔融共混制备了耐热ABS树脂。采用傅里叶变换红外光谱、差示扫描量热法对SMIA树脂进行了表征,探讨了SMIA树脂组成对ABS树脂性能的影响。结果发现：NPMI的引入可以显著提高ABS树脂的耐热性能,当w（NPMI）为10％～20％、m（St）／m（AN）为70：30时,ABS树脂既具有较高的玻璃化转变温度,又具有较好的力学性能。 相似文献
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Shahriar Sajjadi 《American Institute of Chemical Engineers》2009,55(12):3191-3205
The evolution of particle size distribution (PSD) in the monomer‐starved semibatch emulsion polymerization of styrene with a neat monomer feed is investigated using a population balance model. The system under study ranges from conventional batch emulsion to semicontinuous (micro)emulsion polymerization depending on the rate of monomer addition. It is shown that, contrary to what is often believed, the broadness of PSD is not necessarily associated with the length of nucleation period. The PSDs at the end of nucleation are found to be independent of surfactant concentration. Simulation results indicate that at the completion of nucleation the particle size is reduced and the PSD narrows with decreasing rate of monomer addition despite nucleation time increasing. The broad distribution of particles frequently encountered in semibatch emulsion polymerizations is therefore attributed to stochastic broadening during the growth stage. The zero‐one‐two‐three model developed in this article allows perceiving that the dominant kinetic mechanism may be different for particles with different sizes. © 2009 American Institute of Chemical Engineers AIChE J, 2009 相似文献
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J. Esteban López‐Aguilar René O. Vargas Carlos E. Escobar‐Toledo Eduardo Mendizábal Jorge. E. Puig Francisco López‐Serrano 《应用聚合物科学杂志》2015,132(13)
A previously presented model with four states (conversion, active and inactive particles and micelles) is further tested with conversion versus time experimental data at 50, 60, and 70°C, to recognize the main events occurring in styrene microemulsion polymerization. The S‐shaped conversion–with no overprediction‐ and the bell‐shaped active particles number concentration–evidencing diffusive effects at late stages–versus time data, are well described by the proposed model. It was found that: (i) transfer of monomer and surfactant from micelles to particles occurs, (ii) the capture of radicals by micelles is the only cause of particle nucleation, (iii) the rate coefficient of radical‐entry‐to‐micelles is much smaller than that of exit‐from‐particles, and (iv) no coagulation between particles was detected. The Arrhenius dependency on temperature of the kinetic rate parameters is also reported. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41720. 相似文献
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The effects of a series of short chain alcohols, 1‐butanol (C4OH), 1‐pentanol (C5OH), and 1‐hexanol (C6OH), on the styrene (ST) emulsion polymerization mechanisms and kinetics were investigated. The CMC of the ST emulsions stabilized by sodium dodecyl sulfate (SDS) first decreases rapidly and then levels off when the CiOH (i = 4, 5, or 6) concentration ([CiOH]) increases from 0 to 72 mM. Furthermore, at constant [CiOH], the CMC data in decreasing order is CMC (C4OH) > CMC (C5OH) > CMC (C6OH). The effects of CiOH (i = 4, 5, and 6) on the ST emulsion polymerization stabilized by 6 mM SDS are significant. This is attributed to the reduction in CMC by CiOH, the different oil–water interfacial properties, the different concentrations of monomer within latex particles, and the different effectiveness of SDS/CiOH in stabilizing latex particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4406–4411, 2006 相似文献
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S. Sajjadi 《应用聚合物科学杂志》2001,82(10):2472-2477
Semibatch emulsion polymerization processes with a monomer emulsion feed are of great importance in both academia and industry. Monomer emulsion feeds can be applied to semibatch reactors using either a stream of an emulsified monomer or two streams of a neat monomer feed and an aqueous solution of an emulsifier. The effect of the feeding policy on the rate of polymerization and on the secondary particle formation was studied for a seeded semibatch emulsion polymerization of styrene. When a single-stream monomer emulsion feed is applied to a semibatch process, the monomer-swollen micelles formed in the feed might become the locus of initiation upon entering the reaction vessel. Under the conditions of this study, the application of monomer emulsion feed in either one stream or two streams did not result in secondary particle formation. The incoming monomer-swollen micelles were disintegrated to supply emulsifier molecules for the stability of growing particles, before they can capture radicals and become polymer particles. The rate of polymerization was found to be independent of the way that the monomer emulsion feed is added. In the absence of nitrogen, the rate of polymerization decreased more appreciably for the monomer emulsion feed, due to the oxygen dissolved in the emulsified monomer. The number of particles, however, was not affected by the purging policy. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2472–2477, 2001 相似文献
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Chaiwat Norakankorn Qinmin Pan Garry L. Rempel Suda Kiatkamjornwong 《应用聚合物科学杂志》2010,116(3):1291-1298
Functionalized core/shell nanoparticles of the co‐polymer of methyl methacrylate (MMA) and glycidyl methacrylate (GMA) could be polymerized by differential microemulsion polymerization, using a small amount of surfactant (the weight ratio of sodium dodecyl sulfate (SDS)/monomer is 1 : 24). The core/shell nanoparticles have a high conversion, high molecular weight, and small particle size (25–30 nm). The statistical analysis indicated that SDS, water, and the interactionbetween SDS and water have a significant positive interaction between the MMA conversion to form the core nanoparticles. For the core‐shell polymer, [GMA], [GMA]*[SDS], and [GMA]* [water] have significant negative effects on conversion; whereas [SDS] and [water], [SDS]*[water] and [GMA]*[SDS]*[water] have positive effects on the conversion to form core/shell nanoparticles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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This article describes the synthesis and characterization of N-(3-methoxyphenyl) itaconimide (MAI) and N-(4-methoxyphenyl) itaconimide (PAI) obtained by the reaction of itaconic anhydride with m-anisidine and p-anisidine, respectively. Structural and thermal characterization of MAI and PAI monomers was performed with Fourier transform infrared (FTIR), 1H-NMR, differential scanning calorimetry (DSC), and thermogravimetric analysis. Copolymerization of methyl methacrylate (MMA) with various amounts of MAI or PAI ranging from 0.1 to 0.5 was performed in solution with azobisisobutyronitrile as an initiator. Structural and molecular characterization of copolymers was performed with FTIR, 1H-NMR, elemental analysis, and gel permeation chromatography. The nitrogen percentage was used to calculate the copolymer composition. The monomer reactivity ratios for MMA–MAI copolymers were found to be 1.00 ± 0.01 for MMA and 0.99 ± 0.07 for MAI; those for MMA–PAI copolymers were 0.93 ± 0.02 for MMA and 1.11 ± 0.10 for PAI. The molecular weights of the copolymers were in the range of 0.94–9.7 × 103 (number-average molecular weight) and 3.3–101.8 × 103 (weight-average molecular weight), with polydispersity indices in the range of 1.5–4.1. The molecular weight decreased with the increasing molar fraction of imide in the polymer backbone. The glass-transition temperature, as determined from DSC scans, increased with increasing amounts of itaconimides in the copolymers. A significant improvement in the char yield, as determined by thermogravimetry, was observed upon copolymerization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
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主要研究了聚合工艺对丙烯酸酯乳液胶粘剂性能的影响 通过对乳液胶粘剂的各种性能测试,发现3种聚合方法中,种子乳液聚合法制备的乳液胶粘剂的综合性能较为理想 采用种子乳液聚合法,最佳聚合工艺为:单体的滴加时间4h、聚合温度50℃、搅拌速率80 r/min 相似文献