Papers by Keyword: Polystyrene

Abstract: Polymer membranes with fixed pore size or narrow pore size distribution can be used for special separation. However, polymer membranes prepared by conventional method usually have wide pore size distribution and the pore size is hard to control. Here we prepared a porous polymer membrane with uniform pore size via spraying a blend of polystyrene (PS) and polyethylene oxide (PEO) on a filtration paper. Dissolving the water-soluble component (PEO) forms the pore and varying the ratios of PEO in the blend controls the pore size. The pore size and size distribution are also affected by processing parameters, such as the flow rate of solution and carrier gas, and gap length. The morphologies of the membrane are observed using scanning electron microscopy (SEM). The novel polymer membrane with controllable and uniform pore size will be used for the separation of solutes with predictable sizes.

Abstract: Polystyrene-grafted natural rubber (PS-GNR) at various graft levels was evaluated to improve mechanical properties of natural rubber (NR). PS-GNR was synthesized by emulsion copolymerization at 60°C at different reaction times between 15 and 360 mins to control the grafting levels of PS in the PS-GNR co-polymer. The resultant PS-GNR co-polymers were then blended into NR latex. The vulcanized NR compounds were investigated for the effect of PS grafting percentage in PS-GNR/NR compounds on mechanical properties, including tensile, tear strength and hardness. A core-shell structure was revealed with PS encapsulating the NR core via transmission electron microscopy. The polystyrene grafting percentage was determined to be 12.7%, 17.1%, 22.1% and 23.6% for polymerization times of 15 min, 60min, 120min, and 360 min, respectively. Addition of PS-GNR into NR exhibited biphasic behavior, resulting in a decrease in the tensile strength and tear strength. With further increase in grafting percentage of PS, the tensile strength and tear strength continues to decrease. The rigid chain of PS grafted onto NR surface reduced the elasticity of NR chain resulting in lower tear strength and the tensile strength. Fracture surface revealed a decrease in ductility of material with increasing grafting percentage of PS. On the other hand, modulus and hardness of PS-GNR/NR compounds were found to increase with increasing grafting percentage of PS. The addition of PS-GNR to rubber compound had shown an impact on dynamic behavior. With further increase in grafting percentage of PS in PS-GNR, an enhancement of storage modulus of rubber compound was clearly observed.

Abstract: The different amount of hydrophilic hydroxyl group, including 3, 5, 7 and 10 wt.% copoly (styrene-co - divinyl benzene – co - 2-hydroxylethylenemethacrylate) (poly (St- co -DVB- co -HEMA) s) nanoparticles were synthesized via microemulsion polymerization in the present paper. The average size of the poly (St-co-DVB-co-HEMA) s was ca. 44 nm after zetasizer (DLS) measurement and SEM observation. The characteristic peaks at 3200 ~3600 cm^-1 in FTIR was assigned at hydroxyl group of HEMA unit. The NBR/poly (St-co-DVB-co-HEMA) s composites films with 250 μm thickness were prepared simply via latex mixing and followed by spinning coating. The mechanical properties of the poly (St-co-DVB-co-HEMA) s/rubber nanocomposites, including the tensile strength, modulus and elongation, were increased with that of increasing of poly (St-co-DVB-co-HEMA) s adding. In addition, as the poly (St-co-DVB-co-HEMA) s nanoparticles carried out with constant St/HEMA molar ratio of 97:3 and the DVB content in 10 wt.%, the elongation at break that up to more than 3500% and the ultimate stress increased from 0.2 MPa to 0.6 MPa. The poly (St-co-DVB-co-HEMA) s nanoparticles prepared by emulsion polymerization could be successfully enhanced the mechanical properties of rubber latex.

Abstract: In this paper, the lightweight concrete made from polystyrene and ethylene vinyl acetate (EVA) waste was studied. EVA waste from footwear industry and waste polystyrene were used as an aggregate in the lightweight concrete. Each of the plastic wastes was used alone (as a sole aggregate) or in combination with the other in a ratio of 1:3, 1:1 and 3:1. The water-cement ratio of 0.50 and the dose of cement – 175 kg·m^-3 were used for all mixtures. Test results showed that the bulk density and the thermal conductivity of lightweight concrete tended to increase with increasing EVA waste content. The maximum compressive strength of lightweight concrete was reached with the waste materials in a ratio of 1:1. Based on the results, the application of EVA waste as lightweight filler showed a good possibility for use in the lightweight concrete.

Abstract: Electrically conducting composites with a structure of alternating (A-B-A)_n layers were prepared by a novel microlayer coextrusion, which were consisted of alternating layers of polystyrene (PS) and layers of carbon black (CB)-filled polystyrene (PSCB). The co-continuous structure with selective location of CB in PSCB layers was controllable by changing the number of multiplying elements, and decreased the percolation threshold and electrical resistivity of multilayered composites because of the double percolation effect. In addition, the multilayered composites exhibited better mechanical properties than that of the conventional blends, which were related to the layered structure and small size of CB aggregates.

Abstract: Polymer nanocomposites based on polyhedral oligomeric silsesquioxanes (POSS) and their solutions and suspensions are promising systems for fundamental research which could potentially utilize self-assembly approach in designing new nanocomposite materials. Numerous applications could benefit from understanding of these systems, for instance polymer solution based paints and varnishes. This work is an initial stage of a study which aim is to link macroscale thermomechanical properties with nanoscale structures found in polymer nanocomposites. To do so, a suitable experimental protocol for preparing differently organized NPs in polymer matrix has to be find first in which both kinetic and thermodynamical parameters should be taken into account, i.e. solution casting has being investigated. The results presented here found differences between nanoparticle induced changes on rheological behavior of polystyrene solution under large amplitude oscillation shear (LAOS). High-affinity OP-POSS NPs seem to interact with PS at low loadings and form stiffened aggregates, whereas low-affinity OM-POSS NPs remained rather uninvolved. Effect of hydrodynamic forces independent of the NPs chemical nature was also observed.

Abstract: Multi cavity injection molds contain two or more cavities for the fabrication of multiple parts in a single production cycle sharing a mutual batch of thermoplastic resins. The current study simulates the process of performing runner balancing for the two uneven cavities of an electrical box, while it studies the effects of certain injection molding process parameters. The runner layout and the injection locations have been studied and detailed considering the product’s geometries. The runner balancing procedure and the thickness distribution have been also investigated by taking into account the properties of three polymers such as high density polyethylene (HDPE), polystyrene (PS) and polypropylene (PP). The results show that the thickness distribution of the sprue and the runners for the PP and HDPE polymers is quite similar, after the conduction of the runner balancing process; on the contrary, the runners for the PS polymer should be thicker in order to achieve balanced filling within the cavities. The comparison of the materials reveals that PS has certain difficulties to flow under the conditions specified in this study. On the other hand, the injection of PP resulted in excellent balanced fillings, indicating a polymer that is easier to flow. Finally, the HDPE polymer appears to possess the greatest performance in terms of flowability considering the corresponding performances of PP and HDPE polymers.

Abstract: This study observed the influence of solvents on polystyrene regarding the layered morphologies of zinc phthalocyanine (ZnPc) and its influence on the bovine serum albumin (BSA) immobilization on quartz crystal microbalance (QCM) sensor. The larger surface width introduced by surface roughness of the polystyrene due to chloroform (CHCl₃) as the solvents allows more ZnPc to be trapped within the polystyrene. Moreover, the wider surface width also increases the amount of ZnPc to be deposited on top of the polystyrene surface. Therefore, the ZnPc layer deposited onto polystyrene created with CHCl₃ solvent is thicker than other solvents, which result in the largest ∆f of the ZnPc layer.

Abstract: The polymer blends offer end products with better thermo-mechanical properties and they can be more economical. Hence, the interest in the blends by the plastics industry has been increasing and the industry has been moving towards more complex systems.In the present work, an attempt was made to improve compatibility in a polymer blend composed of two normally incompatible constituents, namely, low density polyethylene (LDPE) and polystyrene (PS), through the addition of a compatibilizer. The compatibilizing agent, styrene–ethylene-butadiene–styrene block copolymer (SEBS), was added to the polymer blend in ratios of 5, 10, 20, and 30 wt% with a twin-screw extruder. The morphology and the compatibility of the mixtures were examined by scanning electron microscopy. Further, all blends of LDPE/PS/SEBS were tested to examination to obtain their tribological properties. The result showed that the addition of SEBS to the PS/LDPE blend increased the friction coefficient and the wear rate.

Abstract: Fabrication of high sphericity, monodispersed microspheres (100~600 nm) of various oxides (SiO₂, TiO₂, ZnO, In₂O₃, SnO₂) via sol-gel process and polystyrene (PS) microspheres (200~400 nm) via emulsion polymerization is presented. A high colloidal stability suspension was obtained by adjusting the zeta potential of such spheres and pH of the colloid. The 3-D photonic crystal (PhC) templates of opaline structure on ITO-coated glasses and silicon wafers were easily formed under electrophoretic self-assembly (EPSA) of microspheres under the influence of exerting electrical forces. Different setups of counter-electrode were attempted to establish an electrical field. The lattice constant of an ordered opal structure by EPSA can also be tuned by the electrical field gradient. Interestingly various self-assembled 3-D structures of silica microspheres in either symmetrical curvilinear profile or triangular ridges can be produced through EPSA route using specific counter-electrode setups. The measured optic properties of such 3-D PhC templates manifest photonic bandgap (PBG) based on planar-wave expansion (PWE) simulation to verify the existence of real PBG in PhC samples with tunable nanostructures. The PS PhC templates are currently used to easily transform into inverse opal structure (IOS) by infiltrating sol of other oxides with high dielectric constant (e.g. ZnO or TiO₂) and filled with metallic nanoparticles (Ni or Cu) by electrochemical deposition or chemical bath deposition (CBD).