Papers by Keyword: Polymer Blend

Abstract: Electrical dielectric spectra and alternating current (ac) conductivity of blended poly (N-vinlycarbazole) (PVK) with polyvinylpyrrolidone (PVP) at different temperature are investigated. The polymer blends were prepared by dissolving in dimethylformamide (DMF) using drop casting method and further dried in vacuum oven. The dielectric and ac conductivity of each sample was investigated using electrochemical impedance spectroscopy (EIS) method. Dielectric permittivity studies revealed that there are significant changes in the spectra at different temperature. The ac conductivity was further analyzed by using universal power law. The hopping parameter was calculated by using correlated barrier hopping model.

Abstract: The concept of smart blender to form a multilayer structure of PLA/EVOH has been developed. Unlike conventional mixing, smart blending provides a formation of multilayer structure by dictating the motion of stir rod to agitate melts. The PLA and EVOH are supplied separately by a single-screw extruder. An experimental rig is assembled at the end of a co-extruder, and melt from an extruder entered an experimental rig via a cylindrical port. The molten EVOH is recursively stretched and folded in an experimental rig of PLA major phase to give an alternating layer structure. The rod is rotated by variable speed motor that is independently controllable. The rod rotational speed and volumetric flow rates of EVOH and PLA are of our interest. Careful design of stir rod in smart blending is necessary for effective performance. The computational model provided the visualization of flow profile inside an experimental rig. The simulation determined the geometry of the stir rod required to achieve the spiral flow developed of the melt. The experimental results suggest that the injected streams of EVOH are stretched and folded to multiple and distributed layers ranging thickness from 10 to 200 um. The characteristic folding of EVOH melt depends on the volumetric flow rate of the screw extruder and rod rotational speed. However, the coalescence of EVOH layers is observed for high rod rotational speed.

Abstract: Wheat gluten (WG) plastics are inherently brittle and sensitive to water. In this research, wheat gluten was blended with epoxidized natural rubber containing 50 mol% epoxide group (ENR-50) to improve flexibility and water resistance of WG plastics. Three plasticizers (i.e. glycerol (Gly), polyethylene glycol (PEG) and dioctyl phthalate (DOP) were used to enhance polymer chain mobility and process ability of WG phase in the blends. Differential scanning calorimetry (DSC) was used to evaluate plasticizing efficiency of plasticizers on WG. The DSC result revealed that an excellent plasticizer for WG was glycerol which could remarkably reduce glass transition temperature (T_g) of WG. Furthermore, effect of plasticizer types and contents (0, 10, 20 and 30wt% with respect to protein weight) on morphology, mechanical properties and water absorption of the WG/ENR blends was investigated. It was found that an enhancement in ductility and impact strength of the blends was observed with increasing plasticizer content. Among the plasticized WG/ENR blends, the glycerol-plasticized blend provided better homogenous morphology and superior results in tensile and impact properties. On the other hand, the Gly-plasticized WG/ENR blend showed a low water resistance compared with the blends plasticized with PEG and DOP as well as the unplasticized WG/ENR blend.

Abstract: Blending polymers is an effective method to develop novel materials, tailoring the properties of the components. However, different morphology structures can be formed during the preparation, which could result in a wide diversity of mechanical and physical properties. The properties of polymer blends are most significantly influenced by the emerging range of phase inversion, which depends on the composition ratio and the viscosity ratio. In this paper various blends were prepared, utilizing polyethylene terephthalate (PET), polystyrene (PS) and two high density polyethylenes (HDPE), which differ in flowability. After preliminary homogenization by twin screw extruder, standard injection moulded specimen were prepared in order to present the effects of phase inversion on tensile properties, shrinkage and burning characteristics in binary polymer blends.

Abstract: Nowadays biopolymers are in the focus of many research and Poly (lactic acid) (PLA) is the one of the candidates of this field. The rigid behavior of PLA limits its application field, thus it is mostly used for rigid packing. Our research aim is to increase PLA ductility while keeping the biodegradability as much as possible. In our study, PLA was melt mixed in an internal mixer with 5, 10, 20 and 30 wt% natural rubber. It was possible to increase the toughness to a three time higher value compared to neat PLA while the tensile and flexural properties only decreased maximum 30%.

Abstract: Polymer blend consist of epoxy and polymethylmethacrylate (PMMA) was prepared via two different blending methods. Conventional blending method which required solvent to obtain polymer blend of PMMA and epoxy. However, due to the high consumption of solvent and environmental issue, a new approaching method: direct mixing method was used to prepare the polymer blend without the usage of solvent. The PMMA pellets are grinded and sieved into fine powders and incorporated into epoxy. Comparison between the conventional and new method was done through the investigation based on the morphology and mechanical behaviour, with different PMMA content (0, 10, 20, 30, 40 and 50 vol.%) between two blending methods. In overall, the polymer blend system prepared via direct mixing methods exhibited better mechanical properties as compared to conventional solvent dissolution method. Improvement on fracture toughness was observed in direct mixing method.

Abstract: Previously, the addition of silicon dioxide (SiO₂) improved the homogeneity of polymethyl methacrylate/50 % epoxidised natural rubber (PMMA/ENR 50) blend. However, the presence of SiO₂ agglomerates limits its overall performance. The formation of these agglomerates was due to the hydrogen bonding interaction that form between the oxygen atoms in silanol groups (Si-OH) and hydrogen atoms from the surrounding moisture. Therefore, in this study, SiO₂ were modified with dodecanoic acid (DOA) to reduce the number of Si-OH on the SiO₂ surface using esterification technique. Interestingly, it was found that the addition of DOA modified SiO₂ (D-SiO₂) improves the homogeneity of PMMA/ENR 50 blend. However, the amount of DOA used in the modification affect the capability of forming hydrogen bonding with the neighbouring of polymer chain. Different amounts of DOA were used upon the surface modification of SiO₂ filler and then were added into PMMA/ENR 50 blends doped with lithium tetrafluoroborate (LiBF₄)_. The films were prepared by solvent casting technique. CHNS analysis proven the increases of percentage of carbon atoms in D-SiO₂. The attachment of DOA on SiO₂ surface was confirmed using Fourier transform infrared spectroscopy (FTIR) and ionic conductivity of PMMA/ENR 50/LiBF₄ filled D-SiO₂ films was measured by electrochemical impedance spectroscopy (EIS). The result shows the blend properties and ionic conductivity of PMMA/ENR 50 filled D-SiO₂ films was improved due to surface modification of SiO₂ filler.

Abstract: A Polymer blends compose of Poly (3,4-ethylenedioxythiophene):Poly (styrene sulphonic acid)(PEDOT:PSS) and Polyaniline (PANi) have been prepared using drop casting technique. Optical parameters such as refractive index (n), extinction coefficient (k), reflectance, and optical dielectric were determined in this study. It is found that reflectance spectra increase as the PANi concentration decreases in the sample of small photon energy. The refractive index of the sample shows significant effect with the PEDOT:PSS concentration. As the concentration of PEDOT:PSS increases, the refractive index shows a normal dispersion behavior. Extinction coefficient decrease as the wavelength increase within the range of 300 nm to 350 nm that may contribute to the loss fraction of light due to scattering and the decreasing of absorbance at this range. However, the extinction coefficient increases from 350 nm to the maximum wavelength of 800 nm since the absorbance is also increasing. Both the real and imaginary part of the dielectric constant decreases when the photon energy increases. This revealed that the compositions of PEDOT:PSS influence the optical properties of hybrid PEDOT-PSS:PANi thin film.

Abstract: In this study, HP/ENR blends were prepared in aqueous solution with different hydrophilic polymers for rubber glove donning coating application. HP/ENR blend films were prepared using cast films technique to investigate the film formation prior to coating onto rubber glove. The films surface morphology were characterised using Scanning Electron Microscopy (SEM) and Light Microscopy (LM). While, the thermal properties of the films were determined using Differential Scanning Calorimetry (DSC). The microscopy results showed that coherence film formation can be obtained even though the PVA/ENR and PAA/ENR blends were immiscible. DSC result showed that the glass transition temperature (T_g) of the blends shifted to higher temperature compared with T_g of ENR. The preliminary evaluation of coating onto rubber latex film indicated that PVP/ENR blend is feasible as coating material.

Abstract: Previously, it was found that the addition of SiO₂ filler can improve the homogeneity and enhance the ionic conductivity of lithium tetrafluoroborate (LiBF₄) doped polymethyl methacrylate/50 % epoxidized natural rubber (PMMA/ENR 50) blend from 6.21 x 10^-7 Scm^-1 to 5.26 x 10^-6 Scm^-1. Unfortunately, this SiO₂ filler tend to agglomerates thus obstructing the smoothness in the transportation of lithium ion in the polymer blend matrix. This unruly phenomenon was due to the formation of hydrogen bonding between the oxygen atom of SiO₂ and the hydrogen atom from the moisture. Therefore, in this study, this SiO₂ filler was modified using hydrochloric acid (HCl) to reduce the formation of hydrogen bonding between SiO₂ and moisture. It was found that the modification was able to reduce the hydrogen bond in SiO₂ filler. The CHNS analysis shows that the percentage of hydrogen reduces as concentration of acid increased. This was further confirmed from the FT-IR analysis in which the peak corresponding to Si-OH was reduces meanwhile the peaks corresponding to Si-O-Si increases as HCl concentration increased. As a result, the homogeneity of the blends was further improved. However, the ionic conductivity of the system was found slightly reduce by few magnitudes. Temperature dependence ionic conductivity of LiBF₄ doped PMMA/ENR 50 filled HCl-SiO₂ electrolytes shows nonlinear trend indicates that the system not obeys Arrhenius equation.