Preparation and characterization of soap-free carboxylated polystyrene latexes

Soap-free carboxylated polystyrene latexes have been prepared by copolymerizing carboxylic monomers in a wide range of degree of neutralization using a slight amout of soap. In this polymerization system, the formation of particles seems to be explained by the precipitation of growing radicals formed in the aqueous phase. The degree of neutralization of carboxylic monomers has a great effect on the formation of particles, which may be attributed to a change in the hydrophilic nature of growing radicals formed in aqueous phase that governs the number and uniformity of particles. The number of particles increases remarkably with increasing the amount of soap to some extent, which may be attributed to the stabilization of primary particles formed by the precipitation of growing radicals with the adsorption of soap. The localization of carboxyl groups on the surface of particles seems to be governed by the electrostatic repulsion between carboxyl groups. The surface area occupied by a surface carboxyl group, however, is fairly small irrespective of the degree of neutralization of carboxylic monomers or the amount of soap, which indicates that the latexes are sufficiently stabilized with surface carboxyl groups.     

Preparation and characterization of maleic anhydride-functionalized syndiotactic polystyrene

The free radical-induced grafting of maleic anhydride (MA) onto syndiotactic polystyrene (sPS) has been accomplished in the solution process by using 1,1,2-trichloroethane as solvent and dicumyl peroxide as free radical initiator. The amount of MA grafted on sPS was evaluated by a titration method. Grafted products separated from the reaction mixture were purified and analyzed. Fourier transform infrared spectroscopy and ¹H NMR studies indicate that MA attaches to the sPS in the form of single succinic anhydride rings as well as short oligomers. The results obtained by GPC analysis suggest that the degradation and chain extension reaction do not occur under the reaction conditions. Moreover, the crystallization behavior of MA-functionalized sPS was also studied by means of differential scanning calorimetry. It was found that the crystallization behavior of the grafted polymer exhibited somewhat differences in comparison to the neat sPS. The MA-functionalized sPS crystallizes at higher rate than the unmodified polymer, on the other hand, the degree of crystallinity (X_c) are lowered by the presence of the MA grafts.     

Preparation and characterization of polystyrene foams from limonene solutions

The foaming process has been traditionally performed at high temperature because the CO₂ and the polymer should behave as a homogeneous solution. The addition of a solvent could avoid the high working temperature while the homogeneity is ensured. Among the terpene oils, limonene outlines as a good candidate to carry out the dissolution of polystyrene because it respects the green chemistry principle, it is highly soluble in CO₂ and very compatible with the polymer.The sorption of CO₂ is the first step of the foaming process. The presence of the terpene oil enhances the solubility of the gas which is solubilized in the Polystyrene as well as in the limonene. During the foaming process, many parameters can be tuned to customize the foams. In this work, a fractional factorial design of experiment was proposed to determine the effect of pressure, temperature, concentration of the solution, contact time and vent time over the diameter of cells, its standard deviation and the cells density. The proposed foaming process can be simply performed at mild pressure and temperature thanks to the presence of the solvent. The results showed that the most suitable conditions to foam polystyrene from limonene solutions are 90 bar, 30 °C, 0.1 gPS/ml Lim, 240 min contacting and 30 min venting. Finally, the samples were characterized to determine the amount of residual solvent, their glass transition and degradation temperature checking that the foams presented around 5% of solvent traces but did not show any evidence of degradation.     

季铵化壳聚糖-聚苯乙烯共混膜的制备及表征

以十六烷基三甲基溴化铵(CTAB)为表面活性剂,过硫酸钾为引发剂制备了聚苯乙烯微乳液,用共混法制备了3种不同质量比的季铵化壳聚糖和聚苯乙烯微乳液的共混膜.研究了该膜的温度和pH的敏感性及力学强度.结果表明,共混膜的拉伸强度与纯壳聚糖膜相比有较大提高,而且该膜仍然具有一定的温度敏感性和pH敏感性,有较好的应用价值.     

单分散氢氧化钙/聚苯乙烯微球的制备与表征

以葡萄糖水溶液为反应介质,在氧化钙消化成氢氧化钙的过程中,加入苯乙烯单体和引发剂,采用原位悬浮聚合法成功制备了聚苯乙烯(PS)包覆氢氧化钙[Ca(OH)2]形成Ca(OH)2/PS微球.考察了葡萄糖水溶液、苯乙烯、稳定剂聚乙烯醇以及反应温度对单分散Ca(OH)2/PS微球的粒径及粒子分散系数的影响,得出较佳合成条件.在较佳条件下制备的Ca(OH)2/PS微球平均粒径为30～40 μm,粒子分散系数为0.08～0.10.扫描电镜照片表明,Ca(OH)2/PS具有良好的球形度,表面光滑、无破损.红外光谱表征显示,产物为Ca(OH)2/PS微球.     

Preparation and characterization of thermally conductive polystyrene/carbon nanotubes composites

Thermally conductive polystyrene (PS)/multi‐walled carbon nanotubes (MWNTs) nanocomposites was prepared through a simple solution‐evaporation method assisted by ultrasonic irradiation. To enhance the dispersion of MWNTs in PS, MWNTs were chemically functionalized with poly(styrene‐co‐maleic anhydride) (SMA) (MWNT‐g‐SMA), which had benzene group and exhibited strong affinity with PS. The thermal conductive properties of PS increased and the mechanical properties decreased in presence of MWNTs, while by addition of MWNT‐g‐SMA, the properties of the composites can be improved to some extent. The thermal conductivity can reach 0.89 W/m K for the composite with 33.3 vol % MWNT‐g‐SMA, which was four times higher than that of neat PS. A linear increase of the thermal conductivity was observed with increasing MWNTs‐g‐SMA content, and the Maxwell–Eucken model and the Agari model were used for theoretical evaluation. Compared with MWNT‐OH, MWNT‐g‐SMA with larger diameter exhibited diffused boundary with the PS matrix, resulting from the strong interfacial bonding of the two phases. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of surface modified silicon carbide/polystyrene nanocomposites

A simple method is reported to coat silicon carbide (SiC) nanoparticles with polystyrene (PS) to improve the interfacial adhesion between polymer matrix and SiC nanoparticles. The morphology of untreated SiC nanoparticles, PS coated SiC (p‐SiC) nanoparticles, SiC/PS nanocomposites, and p‐SiC/PS nanocomposites are observed. The HRTEM image of p‐SiC shows that the thickness of PS on the surface of SiC is about 1.5–2.0 nm, which is consistent with the TGA results. With 24.7 vol % untreated SiC nanoparticles dispersed into PS matrix, the thermal conductivity (λ) of the SiC/PS composites increases by about 192%. However, when the same volume fraction of p‐SiC nanoparticles is used, the increase is about 353%. This big difference could be attributed to the promoted dispersion of the p‐SiC in the PS matrix. The measurements of glass transition (T_g), dielectric constant (ε), and tensile strength at break (σ_b) also support this explanation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and rheological characterization of intercalated polystyrene/organophilic montmorillonite nanocomposite

Polystyrene (PS)/organophilic montmorillonite (OMMT) clay nanocomposites were prepared by a solvent casting method using chloroform as a cosolvent. Intercalation of the OMMT in the PS matrix was achieved as revealed by X‐ray diffraction. The IR spectra of the products indicated that the OMMT is homogeneously dispersed in the PS matrix. A thermogravimetric analysis (TGA) showed that the onset temperature increases linearly with the clay content. The glass‐transition temperature of the PS, examined using differential scanning calorimetry, had a trend similar to that from the TGA. The rheological properties of the PS/OMMT nanocomposites were also investigated via a rotational rheometer with a parallel plate geometry, and they exhibited sharper shear thinning and increased storage and loss modulus with clay content. Furthermore, the shear viscosity obtained from the steady shear experiment was well correlated with the complex viscosity obtained from the oscillatory experiment via the Cox and Merz relation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2106–2112, 2003     

聚苯乙烯磺酸钠掺杂正渗透膜的制备及其性能

通过两步无皂乳液聚合法,改变第二步对苯乙烯磺酸钠的加入量,制备表面携带磺酸根基团量不同的纳米粒子（PSS）,并将其应用于正渗透（FO）膜的制备。采用红外光谱仪（FTIR）和光电子能谱仪（XPS）表征粒子组成,通过扫描电子显微镜（SEM）表征膜的表面和断面形貌,测定膜孔隙率和亲水性,考察表面磺酸根量不同的聚合物粒子对膜结构性能的影响。结果表明,PSS的引入能提高膜的孔隙率,改善膜的亲水性,且随着粒子表面携带的磺酸根基团量增多,膜的孔隙率与亲水性也随之提高。这是因为PSS粒子可以支撑内部孔道,且表面携带的亲水基团-SO3Na可以提高膜的亲水性,影响活性层的形成。所制备的FO膜性能也得到相应改善,水通量达到了61.1L/(m²·h),为纯聚砜膜的2.8倍,盐截留率达到93.2%,J_s/J_v值仅为0.31g/L,性能得到极大提升。     

Preparation and characterization of polystyrene sulfonic acid-co-maleic acid copolymer modified silica nanoparticles

Two types of silanes, including 3-glycidoxypropyltrimethoxysilane (GPTMS) and 3-aminopropyltriethoxysilane (APTES), were grafted onto polystyrene sulfonic acid-co-maleic acid (PSSA_MA) first, followed by the grafting reaction to the silica surface. The modification of PSSA_MA onto silica was confirmed through FTIR (Fourier transform infrared spectrum), NMR (Nuclear magnetic resonance), and TGA (Thermogravimetric analysis). The grafting ratio of PSSA_MA via APTES with 1-ethyl-3-(3- dimethylaminopropyl)-carbodiimide (EDC) activation reached 18.0 %. As for GPTMS case, the grafting ratio reached 14.4 %, which was slightly lower than that of APTES case. The grafting mechanisms for both cases were elucidated. The epoxysilane was found to react with maleic acid groups on PSSA_MA only. On the other hand, the aminosilane not only interacted with sulfonic groups but also activated maleic acid groups via EDC. However, without the use of the coupling agent, the grafting degree of PSSA_MA was only 3 %, which signified the essential role of coupling agents in this organically modified silica. The average particle size of silica was around 200 nm with or without organic modification from transmission electron microscopy (TEM) and Zetasizer analysis. The APTES-modified samples showed the highest improvement in the ion adsorption capacity in all investigated cases.     

Preparation and characterization of polystyrene modified single‐walled carbon nanotube

A halogen atom terminated Polystyrene (PSt) was prepared by means of atom transfer radical polymerization. Then, the halogen atom was converted into ‐N₃ group and a ‐N₃ terminated PSt was obtained. Finally PSt was grafted onto the surface of single walled carbon nanotube (SWNT) by the reaction of azide group with SWNT. Comparison of X‐ray photoelectron spectrometer of N1s electron belonging to ‐N₃ and the surface of SWNT demonstrated that three‐membered rings were formed by releasing N₂ from ‐N₃ during the reaction. The structure of PSt modified SWNT was characterized by FTIR, UV, Raman spectrum, and TEM. The experimental results showed that the PSt was connected assuredly to SWNT by the covalent bond. TGA data showed that the amount of PSt on the surface of SWNT firstly increased with growing of PSt and then decrease when continues to grow. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

聚苯乙烯增强的室温硫化硅橡胶的制备及表征

以过氧化苯甲酰(BPO)为引发剂,使苯乙烯(St)在α,ω-羟基聚二甲基硅氧烷(PDMS)的甲苯溶液中进行自由基聚合制备PDMS/聚苯乙烯(PS)共混物,在甲基三乙氧基硅烷与PDMS的质量比为1∶1时,制得PS增强的室温硫化硅橡胶。研究了原料配比、BPO用量和甲苯用量对硅橡胶力学性能的影响,并对其微观结构进行了表征。结果表明,当PDMS/St(质量比)为60/40、BPO为PDMS质量的2.5%、甲苯/PDMS(质量比)为2时,所得硅橡胶的拉伸强度可达到3.8 MPa,PS的增强效果明显;该室温硫化硅橡胶具有微相分离结构,PS作为分散相分布于PDMS连续相中,且具有2个玻璃化转变温度。     

表面接枝高密度磺酸基聚苯乙烯的制备及表征

以无水溴化铝为催化剂,对氯苯甲醛为醛基化试剂,通过傅克反应在聚苯乙烯微球表面接枝醛基;基于醛基的可氧化性,利用还原剂硝酸铵铈将树脂微球表面的醛基自由基化,引发对苯乙烯磺酸钠在树脂微球表面聚合,并对其进行表征。结果表明,聚苯乙烯微球磺酸化改性成功,优化的磺化工艺条件为:醛基含量1.5 mmol/g的聚苯乙烯微球用量0.3 g,对苯乙烯磺酸钠质量浓度40 g/L,硝酸铵铈质量浓度40 g/L,反应温度70℃,在此条件下制备的树脂表面磺酸基含量为58 mmol/g。     

聚苯乙烯增强室温硫化硅橡胶的制备及表征

以过氧化苯甲酰为引发剂,使苯乙烯在α,ω-羟基聚(二甲基-甲基乙烯基)硅氧烷(PDM-MVS)中进行自由基聚合,制备了PDM-MVS/聚苯乙烯(PS)共混物。将该共混物在室温下进行硫化,获得了PS增强的室温硫化硅橡胶,并对硅橡胶的力学性能和微观形态进行了表征。结果表明,目标硅橡胶的拉伸强度和扯断伸长率均随PDM-MVS中乙烯基质量分数的增加而增大,当乙烯基质量分数为1.50%时,其拉伸强度达3.9 MPa,扯断伸长率达416%,PS的增强效果明显;目标硅橡胶具有微相分离结构,PS作为分散相均匀分布于PDM-MVS连续相中,两相的相容性随着PDM-MVS中乙烯基质量分数的增加而增强。     

Preparation and characterization of porous titanium dioxide sulfonated polystyrene composite microspheres with amphiphilicity

Porous particles with amphiphilicity were prepared by a nonpolymeric pore‐formation process with the sulfonation of polystyrene microspheres. Nano titanium dioxide (TiO₂) particles were then grafted onto the surface via a sol–gel method to finally form the composite particles. The effects of the mass ratio of ethanol (EtOH) to water, temperature, and solubility parameter on the pore‐formation process is discussed in detail. The morphology, porous structure, and wetting properties of the particles were studied by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and contact angle measurement. The results show that porous sulfonated polystyrene (SP) microspheres could be fabricated at 60°C with a 1 : 1 mass ratio of EtOH–water and a solubility parameter of 29.69 MPa^1/2. The TiO₂ particles were determined to be grafted onto the SP microspheres by physical‐bond interaction on the basis of FTIR analysis. The contact angles for both water (aqueous‐phase) and various organic solvent (oil‐phase) droplets with different polarities on the surface of compressed tablets of TiO₂–SP powder were all lower than 30°; this indicated excellent amphiphilicity in the composite particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of polystyrene/graphite composite prepared by cationic grafting polymerization

A new graphite/polystyrene composite was produced with cationic grafting polymerization of styrene initiated by CO⁺ClO⁻₄ group on the surface of expanded graphite (EG). The structures of EG and the graphite/polystyrene composite were studied with SEM and optical micrograph. The spectra of XRD and IR were used not only for confirming whether the polymerization reaction took place, but also for determining whether the polystyrene in the composite covered the surface of EG particles or intercalated into EG particles. The electrical conductivity, thermal phase transitions and mechanical properties were also discussed.     

Preparation and characterization of syndiotactic polystyrene/ethylene‐propylene copolymer blends

The reactive compatibilization of syndiotactic polystyrene (sPS)/oxazoline‐styrene copolymer (RPS)/maleic anhydride grafted ethylene‐propylene copolymer (EPR‐MA) blends is investigated in this study. First, the miscibility of sPS/RPS blends is examined by thermal analysis. The cold crystallization peak (T_cc) moved toward higher temperature with increased PRS, and, concerning enthalpy relaxation behaviors, only a single enthalpy relation peak was found in all aged samples. These results indicate that the sPS/RPS blend is miscible along the various compositions and RPS can be used in the reactive compatibilization of sPS/RPS/EPR‐MA blends. The reactive compatibilized sPS/RPS/EPR‐MA blends showed finer morphology than sPS/EPR‐MA physical blends and higher storage modulus (G') and complex viscosity (η*) when RPS contents were increased. Moreover, the impact strength of sPS/RPS/EPR‐MA increased significantly compared to sPS/EPR‐MA blend, and SEM micrographs after impact testing show that the sPS/RPS/EPR‐MA blend has better adhesion between the sPS matrix and the dispersed EPR‐MA phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2084–2091, 2002     

高1,2-间同聚丁二烯/聚苯乙烯原位共混物的制备与表征

在聚苯乙烯(PS)基体中采用原位生成方法制备了高1,2-间同聚丁二烯(s-PB)／PS原位共混物,并进行了差示扫描量热分析。结果表明,该共混物为部分相容体系,随着PS用量的增加,s-PB的结晶温度及结晶度都随之下降。