Exfoliated polystyrene (PS)/laponite nanocomposites were prepared successfully. The characteristic doo1 diffraction peak of organo-laponite disappeared in the XRD patterns of nanocomposites, indicating that the laponite layers were exfoliated and the ordered crystal structure of laponite was destroyed because of the styrene polymerization. TEM observations showed that the exfoliated laponite primary particles were dispersed randomly in the PS matrix with lateral dimensions from 1 nm to 10 rim. SEM results showed that the PS/laponite nanocomposite particles were almost monodispersed spheres with the size of about 120 rim. Because of the interaction between PS and laponite nanolayers, the nanocomposites exhibited higher thermal stability and glass transition temperature when compared to pure PS. 相似文献
Styrene butadiene rubber (SBR) composites filled with fillers, such as modified kaolinite (MK), precipitated silica (PS), and the hybrid fillers containing MK and PS, were prepared by melt blending. The kaolinite sheets were finely dispersed in the SBR matrix around 20–80 nm in thickness and reached the nano-scale. The SBR composites with fillers exhibited excellent thermal stability compared to the pure SBR. The thermal stability of SBR composites was improved with the increasing of MK mass fraction. When MK hybridized with PS, kaolinite sheets were covered by the fine silica particles and the interface between filler particles and rubber matrix became more indistinct. SBR composite filled by hybrid fillers containing 40 phr MK and 10 phr PS became more difficult in decomposition and was better than that of 50 phr PS/SBR and 50 phr MK/SBR in thermal stability. Therefore, the hybridization of the fine silica particles with the kaolinite particles can effectively improve the thermal stability of SBR composites. 相似文献
Inorganic nanoparticles are widely used to improve space charge behavior, DC breakdown strength and other electrical properties of polymer insulating materials, but the uniform distribution of inorganic nanofillers in matrix is difficult due to their agglomeration and bad compatibility with the polymeric matrix. In this paper, polypropylene (PP)/polystyrene (PS) blends were prepared to suppress space charge accumulation and improve DC breakdown strength. Polypropylene-g-polystyrene (PP-g-PS) graft copolymer was used as compatibilizer to improve the compatibility of PP matrix and PS filler. The evolution of microstructure of PP/PS blends were investigated by scanning electron microscope (SEM), the space charge distributions were measured by a pulsed electro-acoustic (PEA) system, and DC breakdown strength was also tested. The morphologies show that the size of PS particles reduced to 310 nm when the content of PP-g-PS graft copolymer increased to 24 wt%, and the interaction between PP matrix and PS particles enhanced. The presence of PS particles in all PP/PS blends suppressed the space charge accumulation compared to neat PP, but the DC breakdown strength in uncompatibilized blend was lower than neat PP. The increasing of content of PP-g-PS improved the DC breakdown strength with the maximum value of 408.9 kV/mm was obtained. This may attribute to excellent interface structure formed between PP matrix and PS particles. 相似文献
Polystyrene/iron-nickel (PS/FeNi3) nanocomposites were synthesized via an in-situ polymerization route and characterized by XRD,SEM and FTIR. FeNi3 nanoparticles were characterized by TEM and XRD. The pure FeNi3 nanoparticles (100~125 nm) were highly clustered and percolated through the PS matrix. When the content of FeNi3 nanoparticles reached 5 wt%,an interaction between FeNi3 nanoparticles and PS matrix was observed. The thermal decomposition behavior of PS/FeNi3 nanocomposites was investigated by thermal analysis. The activation energies (E) and pre-exponential factors (lnA) were calculated by using Archar method. The results show that the thermal decomposition of pure PS is a one-dimensional diffusion mechanism. A three-dimensional diffusion mechanism appears when FeNi3 nanoparticles incorporate. The E of PS/FeNi3 nanocomposites with different FeNi3 contents is 217.5,225.3,180.6 and 73.0 kJ·mol-1,and the corresponding lnA is 35.6,34.9,27.5 and 10.4 S-1,respectively. 相似文献
This study describes the preparation of polyaniline (PANI) coated on the surface of monodispersed 400 nm polystyrene (PS) particles by in situ chemical oxidative polymerization. The monodispersed 400 nm PS particles served as cores were synthesized using the emulsion polymerization. Both images observed by field-emission scanning electron microscopy and transmission electron microscopy show the presence of a thin PANI layer uniformly coated on the surface of PS particle. The electrical conductivity of various amounts of PANI-coated PS particles is significantly increased about 13 orders of magnitude compared to that of the pristine PS particles. Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to investigate the thermal stability and thermal degradation behavior of PS and PANI-coated PS particles. Both DSC and TGA curves revealed that the coating of a thin PANI layer on the surface of PS can drastically increase the thermal stability of PS matrix. TGA isothermal degradation data illustrate that the activation energy of the PANI-coated PS particle is larger than that of PS. This phenomenon can be attributed to the incorporation of PANI coating on the surface of PS particle caused a decrease in the degradation rate and an increase in the residual weight for the PANI-coated PS particle. 相似文献
Polystyrene (PS)/layered double hydroxides (LDHs) composites were prepared for the first time from LDHs aqueous suspension
and PS emulsion by electrostatic assembly. The morphology characterization based on XRD and TEM showed that the LDHs were
partially exfoliated in PS matrix. By using a reactive emulsifier, i.e., sodium 2-hydroxyl-3-(methacryloxy)propane-1-sulfonate
(HMPS), which was able to copolymerize with styrene, a strong polymer-LDHs platelets interaction was achieved. The glass transition
temperature (Tg) of the composites was measured by DSC and DMA. The results showed that a strong polymer-LDHs platelets interaction played
a dominant role in affecting the mobility of polymer chains, i.e., the Tg. With a strong interaction, PS-HMPS/LDHs composite showed a significant enhancement in Tg while a slight increase in Tg was observed for PS-SDS (PS prepared by emulsion polymerization using sodium dodecyl sulfate as emulsifier)/LDHs composite
with a weak interaction. The addition of LDHs improved the thermal stability of PS, and the improvement depended on the dispersion
of the LDHs platelets. 相似文献
In this study, polystyrene (PS) was melt blended with different amounts of poly1‐hexene (PH) and poly(1‐hexene‐co‐hexadiene) (COPOLY) and the blends were compared with conventional PS/polybutadiene (PS/PB) one. Scanning electron microscope revealed that the dispersion of PH and COPOLY in PS matrix was more uniform with the appearance of small particles in PS matrix; however, in the case of PS/PB blends, the fracture surface showed nonhomogenous morphology with the appearance of bigger rubber particles. Based on Differential Scanning Calorimetry (DSC) and dynamic mechanical thermal analysis results, Tg of the blends decreased in comparison with it in neat PS. Impact strength of PS/PH and PS/COPOLY blends was considerably higher than that in PS/PB and significantly higher than the value for neat PS. Tensile test showed substantial improvement in stress at yield and better elongation at break for COPOLY containing blend than the samples containing PH and PB rubbers. Also, blending of PS with 10% of the rubbers was considered in the presence of dicumylperoxide as a probable grafting/cross‐linking agent to produce XPS/COPOLY10 and XPS/PB10 samples, respectively. IR results of the nonsoluble solvent extracted gel showed that COPOLY and PB were grafted to PS matrix during melt blending, which caused higher impact strength in the related samples. 相似文献
A novel and versatile approach for the mixing of ZnO nanofillers into a host polymer matrix, poly(ethyl methacrylate) (PEMA), is reported. Firstly, ZnO nanoparticles are deposited onto the surface of polystyrene (PS) colloidal particles in a “raspberry‐like” fashion and subsequently obtained PS/ZnO composite particles are mixed into the PEMA matrix in the range of 0.5 to 5 wt.‐%. Microscopic analyses reveal a homogenous distribution of PS/ZnO domains into the PEMA matrix even at 5 wt.‐% loading level. Thermogravimetric analysis and differential scanning calorimetry results indicate an improvement in thermal stability of PEMA matrix after mixing with PS/ZnO filler particles. A significant enhancement in mechanical properties of PEMA matrix in the presence of PS/ZnO particles has been evidenced by dynamic mechanical analysis and three point bending measurements.
The potential of cathodic protection of steel with composite coatings based on polystyrene (PS) filled by highly dispersed
powders of zinc (Zn) of different forms and dispersivities is investigated. The potential for all PS/Zn systems with a low
content of filler is shown to be less than for pure metal; as some critical value (the percolation threshold) is reached,
the negative values of potential increase abruptly and become higher in absolute value than the potential of pure metal. The
threshold zinc contents are found to depend on the particle shape and rise from 9 to 30 vol% upon transitioning from spear-shaped
to spherical particles. The electrochemical protection properties of a composite coating are correlate with the enthalpy of
mixing of filled composites. The enthalpy of mixing in regions of low filling is shown to be negative, indicating strong interphase
interaction; that in regions of high filling is positive. The positive enthalpy of mixing corresponds to compositions that
generate the potential of cathodic protection. It is found that an increase in the concentration range of positive values
of a composition’s enthalpy of mixing occurs symbatically with a decrease in the threshold concentration of metallic zinc
within the composition. We conclude that cathodic protection by zinc-filled polymeric composites is due to weak interphase
interaction that results in the aggregation of particles of metallic zinc within a polymeric matrix and the appearance of
an infinite cluster. In the case of PS/Zn compositions, it is shown that the infinite cluster appears at enthalpies of mixing
greater than 0.6 J/g of the composition. 相似文献
Electrically conducting polystyrene (PS)/polyaniline blends have been prepared through a one-step “anilinium-surfactant template”-assisted emulsion polymerization at room temperature. The self-assembled cylindrical An+PDPSA? micelle formed inside the PS matrix can act as a structure directing template cum dopant. Morphological observation under scanning electron microscopic studies revealed that during the progress of polymerization, the initially formed nanostructured conducting polyaniline was changed into cubic/hexagonal/lamellar particles and finally transformed into a percolated structure inside the PS matrix. Blend was further characterized by UV-Vis spectroscopy, FTIR spectroscopy, X-ray diffraction, electrical conductivity, thermal stability, dielectric property, rheological property, and electromagnetic shielding efficiency. The key finding of this work is that the conductive blend prepared through micelle-guided polymerization exhibited superior electrical conductivity (9.6 S/m) with low percolation threshold concentration (5 wt%), excellent thermal stability, electromagnetic interference (EMI) SE of 1–10 dB which makes it a promising candidate for EMI shielding and antistatic discharge matrix for the encapsulation of microelectronic devices. 相似文献
Monolayer films of hexagonal close-packed polystyrene (PS) spheres were formed at the air-water interface through a self-ordering process without using Langmuir trough. The contact angle of PS particles on the surface of water was determined by an interfacial swelling method. It was found that the concentration and the nature of surfactant had an obvious influence on the arrangement of PS particles. PS suspension containing Triton X 100 (TX 100) of an appropriate concentration self-assembled into a closely packed monolayer on the surface of water. Sodium dodecyl sulfonate, an anionic surfactant, had a relative weak influence on the arrangement of pre-dried PS particles, in contrast, had an obvious effect on newly synthesized PS particles. Quantitative ultraviolet-visible (UV-vis) absorption spectrometry indicated that about 3% of the added TX 100 was adsorbed on the PS particle surface. Laser diffraction patterns on the monolayer film were used to investigate the lattice orientation. Ultraviolet-visible-near infrared (UV-vis-NIR) spectra of monolayer films of different sized PS particles displayed that the method presented here was universal for preparation of two-dimensional (2D) colloidal crystals. 相似文献
The preparation and characterization of polymer blends with structured natural rubber (NR)-based latex particles are presented. By a semicontinuous emulsion polymerization process, a natural rubber latex (prevulcanized or not) was coated with a shell of crosslinked polymethylmethacrylate (PMMA) or polystyrene (PS). Furthermore, core–shell latexes based on a natural rubber/crosslinked PS latex semi-interpenetrating network were synthesized in a batch process. These structured particles were incorporated as impact modifiers into a brittle polymer matrix using a Werner & Pfleiderer twin screw extruder. The mechanical properties of PS and PMMA blends with a series of the prepared latexes were investigated. In the case of PMMA blends, relatively simple core (NR)–shell (crosslinked PMMA) particles improved the mechanical properties of PMMA most effectively. An intermediate PS layer between the core and the shell or a natural rubber core with PS subinclusions allowed the E-modulus to be adjusted. The situation was different with the PS blends. Only core–shell particles based on NR-crosslinked PS latex semi-interpenetrating networks could effectively toughen PS. It appears that microdomains in the rubber phase allowed a modification of the crazing behavior. These inclusions were observed inside the NR particles by transmission electron microscopy. Transmission electron photomicrographs of PS and PMMA blends also revealed intact and well-dispersed particles. Scanning electron microscopy of fracture surfaces allowed us to distinguish PS blends reinforced with latex semi-interpenetrating network-based particles from blends with all other types of particles. 相似文献
Poly(bis(phenoxy)phosphazene) (SPBPP)/phosphotungstic acid (PWA)/silica composite membranes for fuel cells were prepared. The composite membranes were characterized by using FTIR, TGA and SEM techniquies. Incorporation of PWA particles and silica particles into the SPBPP polymer matrix and a specific interaction between them were confirmed by FTIR spectra. TGA results showed that the composite membranes had high thermal stability. Homogeneous distribution of PWA and silica particles within the SPBPP matrix was verified by SEM micrographs. The doped membranes showed increased water uptake and proton conductivity. 相似文献
This paper reports the preparation of cross-linked core-shell poly(butyl acrylate)/polystyrene (PBA/PS) and poly(butyl acrylate)/poly(methyl
methacrylate) (PBA/PMMA) nanoparticles via seeded emulsion polymerization and their application in nylon-based composites.
A highly cross-linked structure was formed in both the cores and the shells by using a cross-linking agent, which could prevent
the migration of hydrophobic PS shells to the inside of particles. There were covalent bonds on the interfaces between the
cores and the shells of both particles. The average particle sizes were 40–50 nm, and the size distributions were narrow.
The kinetics of polymerization was investigated. Well-defined core-shell structure and narrow particle size distribution could
be achieved under starved conditions of monomer feeding. Furthermore, PBA/PMMA particles were used to fill nylon 6, good dispersion
was obtained because of the strong interfacial interaction between the nanoparticles and the nylon 6 matrix and the good deformation
ability of nanoparticles, and the toughness and rigidity of the composites were improved evidently.
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Translated from Acta Polymerica Sinica, 2005, (6) (in Chinese) 相似文献