Displaying publications 1 - 20 of 571 in total

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  1. Hosen MA, Jumaat MZ, Alengaram UJ, Islam ABMS, Bin Hashim H
    Polymers (Basel), 2016 Mar 03;8(3).
    PMID: 30979167 DOI: 10.3390/polym8030067
    Existing structural components require strengthening after a certain period of time due to increases in service loads, errors in design, mechanical damage, and the need to extend the service period. Externally-bonded reinforcement (EBR) and near-surface mounted (NSM) reinforcement are two preferred strengthening approach. This paper presents a NSM technique incorporating NSM composites, namely steel and carbon fiber-reinforced polymer (CFRP) bars, as reinforcement. Experimental and analytical studies carried out to explore the performance of reinforced concrete (RC) members strengthened with the NSM composites. Analytical models were developed in predicting the maximum crack spacing and width, concrete cover separation failure loads, and deflection. A four-point bending test was applied on beams strengthened with different types and ratios of NSM reinforcement. The failure characteristics, yield, and ultimate capacities, deflection, strain, and cracking behavior of the beams were evaluated based on the experimental output. The test results indicate an increase in the cracking load of 69% and an increase in the ultimate load of 92% compared with the control beam. The predicted result from the analytical model shows good agreement with the experimental result, which ensures the competent implementation of the present NSM-steel and CFRP technique.
    Matched MeSH terms: Polymers
  2. Shahabudin N, Yahya R, Gan SN
    Polymers (Basel), 2016 Apr 06;8(4).
    PMID: 30979216 DOI: 10.3390/polym8040125
    One of the approaches to prolong the service lifespan of polymeric material is the development of self-healing ability by means of embedded microcapsules containing a healing agent. In this work, poly(melamine-urea-formaldehyde) (PMUF) microcapsules containing a palm oil-based alkyd were produced by polymerization of melamine resin, urea and formaldehyde that encapsulated droplets of the suspended alkyd particles. A series of spherical and free-flowing microcapsules were obtained. The chemical properties of core and shell materials were characterized by Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and proton nuclear magnetic resonance spectroscopy (¹H-NMR). Differential scanning calorimetry (DSC) analysis showed a glass transition around -15 °C due to the alkyd, and a melting temperature at around 200 °C due to the shell. Thermogravimetric analysis (TGA) results showed that the core and shell thermally degraded within the temperature range of 200⁻600 °C. Field emission scanning electron microscope (FESEM) examination of the ruptured microcapsule showed smooth inner and rough outer surfaces of the shell. Flexural strength and microhardness (Vickers) of the cured epoxy compound were not affected with the incorporation of 1%⁻3% of the microcapsules. The viability of the healing reactions was demonstrated by blending small amounts of alkyd with epoxy and hardener at different ratios. The blends could readily cure to non-sticky hard solids at room temperature and the reactions could be verified by ATR-FTIR.
  3. Al-Hada NM, Saion E, Talib ZA, Shaari AH
    Polymers (Basel), 2016 Apr 08;8(4).
    PMID: 30979222 DOI: 10.3390/polym8040113
    Cadmium oxide semiconductor nanoparticles were produced using a water based mixture, incorporating cadmium nitrates, polyvinyl pyrrolidone (PVP), and calcination temperature. An X-ray diffraction (XRD) evaluation was conducted to determine the degree of crystallization of the semiconductor nanoparticles. In addition, scanning electron microscopy (SEM) was conducted to identify the morphological features of the nanoparticles. The typical particle sizes and particle dispersal were analyzed via the use of transmission electron microscopy (TEM). The findings provided further support for the XRD outcomes. To determine the composition phase, Fourier transform infrared spectroscopy (FT-IR) was conducted, as it indicated the existence of not only metal oxide ionic band in the selection of samples, but also the efficient removal of organic compounds following calcinations. The optical characteristics were demonstrated, so as to analyze the energy band gap via the use of a UV⁻Vis spectrophotometer. A reduced particle size resulted in diminution of the intensity of photoluminescence, was demonstrated by PL spectra. Plus, the magnetic characteristics were examined using an electron spin resonance (ESR) spectroscopy, which affirmed the existence of unpaired electrons.
  4. Mahmood Raouf R, Abdul Wahab Z, Azowa Ibrahim N, Abidin Talib Z, Chieng BW
    Polymers (Basel), 2016 Apr 14;8(4).
    PMID: 30979233 DOI: 10.3390/polym8040128
    The use of transparent polymers as an alternative to glass has become widespread. However, the direct exposure of these materials to climatic conditions of sunlight and heat decrease the lifetime cost of these products. The aim of this study was to minimize the harm caused by ultraviolet (UV) radiation exposure to transparent poly(methylmethacrylate) (PMMA), which usually leads to changes in the physical and chemical properties of these materials and reduced performance. This was achieved using environmentally friendly cellulose acetate butyrate (CAB). The optical, morphological, and thermal properties of CAB blended with transparent PMMA was studied using UV-VIS spectrophotometry, scanning electron microscopy, X-ray diffraction, dynamic mechanical analysis, and thermal gravimetric analysis. The results show that CAB was able to reduce the effects of UV radiation by making PMMA more transparent to UV light, thereby preventing the negative effects of trapped radiation within the compositional structure, while maintaining the amorphous structure of the blend. The results also show that CAB blended with PMMA led to some properties commensurate with the requirements of research in terms of a slight increase in the value of the modulus and the glass transition temperature for the PMMA/CAB blend.
    Matched MeSH terms: Polymers
  5. Baharin SNA, Muhamad Sarih N, Mohamad S
    Polymers (Basel), 2016 Apr 28;8(5).
    PMID: 30979266 DOI: 10.3390/polym8050117
    Poly(phenyl-(4-(6-thiophen-3-yl-hexyloxy)-benzylidene)-amine) (P3TArH) was successfully synthesized and coated on the surface of Fe₃O₄ magnetic nanoparticles (MNPs). The nanocomposites were characterized by Fourier transform infra-red (FTIR), X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, analyzer transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). P3TArH-coated MNPs (MNP@P3TArH) showed higher capabilities for the extraction of commonly-used phthalates and were optimized for the magnetic-solid phase extraction (MSPE) of environmental samples. Separation and determination of the extracted phthalates, namely dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), dicyclohexyl phthalate (DCP), di-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DNOP), were conducted by a gas chromatography-flame ionization detector (GC-FID). The best working conditions were as follows; sample at pH 7, 30 min extraction time, ethyl acetate as the elution solvent, 500-µL elution solvent volumes, 10 min desorption time, 10-mg adsorbent dosage, 20-mL sample loading volume and 15 g·L-1 concentration of NaCl. Under the optimized conditions, the analytical performances were determined with a linear range of 0.1⁻50 µg·L-1 and a limit of detection at 0.08⁻0.468 µg·L-1 for all of the analytes studied. The intra-day (n = 7) and inter-day (n = 3) relative standard deviations (RSD%) of three replicates were each demonstrated in the range of 3.7⁻4.9 and 3.0⁻5.0, respectively. The steadiness and reusability studies suggested that the MNP@P3TArH could be used up to five cycles. The proposed method was executed for the analysis of real water samples, namely commercial bottled mineral water and bottled fresh milk, whereby recoveries in the range of 68%⁻101% and RSD% lower than 7.7 were attained.
  6. Liew CW, Ng HM, Numan A, Ramesh S
    Polymers (Basel), 2016 May 18;8(5).
    PMID: 30979292 DOI: 10.3390/polym8050179
    Nanocomposite polymer electrolyte membranes (NCPEMs) based on poly(acrylic acid)(PAA) and titania (TiO₂) are prepared by a solution casting technique. The ionic conductivity of NCPEMs increases with the weight ratio of TiO₂.The highest ionic conductivity of (8.36 ± 0.01) × 10-4 S·cm-1 is obtained with addition of 6 wt % of TiO₂ at ambient temperature. The complexation between PAA, LiTFSI and TiO₂ is discussed in Attenuated total reflectance-Fourier Transform Infrared (ATR-FTIR) studies. Electrical double layer capacitors (EDLCs) are fabricated using the filler-free polymer electrolyte or the most conducting NCPEM and carbon-based electrodes. The electrochemical performances of fabricated EDLCs are studied through cyclic voltammetry (CV) and galvanostatic charge-discharge studies. EDLC comprising NCPEM shows the specific capacitance of 28.56 F·g-1 (or equivalent to 29.54 mF·cm-2) with excellent electrochemical stability.
    Matched MeSH terms: Polymers
  7. Jakir Hossain Khan M, Azlan Hussain M, Mujtaba IM
    Polymers (Basel), 2016 Jun 14;8(6).
    PMID: 30979325 DOI: 10.3390/polym8060220
    In this study, a novel multiphasic model for the calculation of the polypropylene production in a complicated hydrodynamic and the physiochemical environments has been formulated, confirmed and validated. This is a first research attempt that describes the development of the dual-phasic phenomena, the impact of the optimal process conditions on the production rate of polypropylene and the fluidized bed dynamic details which could be concurrently obtained after solving the model coupled with the CFD (computational fluid dynamics) model, the basic mathematical model and the moment equations. Furthermore, we have established the quantitative relationship between the operational condition and the dynamic gas⁻solid behavior in actual reaction environments. Our results state that the proposed model could be applied for generalizing the production rate of the polymer from a chemical procedure to pilot-scale chemical reaction engineering. However, it was assumed that the solids present in the bubble phase and the reactant gas present in the emulsion phase improved the multiphasic model, thus taking into account that the polymerization took place mutually in the emulsion besides the bubble phase. It was observed that with respect to the experimental extent of the superficial gas velocity and the Ziegler-Natta feed rate, the ratio of the polymer produced as compared to the overall rate of production was approximately in the range of 9%⁻11%. This is a significant amount and it should not be ignored. We also carried out the simulation studies for comparing the data of the CFD-dependent dual-phasic model, the emulsion phase model, the dynamic bubble model and the experimental results. It was noted that the improved dual-phasic model and the CFD model were able to predict more constricted and safer windows at similar conditions as compared to the experimental results. Our work is unique, as the integrated developed model is able to offer clearer ideas related to the dynamic bed parameters for the separate phases and is also capable of computing the chemical reaction rate for every phase in the reaction. Our improved mutiphasic model revealed similar dynamic behaviour as the conventional model in the initial stages of the polymerization reaction; however, it diverged as time progressed.
    Matched MeSH terms: Polymers
  8. Mhd Haniffa MAC, Ching YC, Abdullah LC, Poh SC, Chuah CH
    Polymers (Basel), 2016 Jun 29;8(7).
    PMID: 30974522 DOI: 10.3390/polym8070246
    The properties of a composite material depend on its constituent materials such as natural biopolymers or synthetic biodegradable polymers and inorganic or organic nanomaterials or nano-scale minerals. The significance of bio-based and synthetic polymers and their drawbacks on coating film application is currently being discussed in research papers and articles. Properties and applications vary for each novel synthetic bio-based material, and a number of such materials have been fabricated in recent years. This review provides an in-depth discussion on the properties and applications of biopolymer-based nanocomposite coating films. Recent works and articles are cited in this paper. These citations are ubiquitous in the development of novel bionanocomposites and their applications.
    Matched MeSH terms: Biopolymers; Polymers
  9. Darain KMU, Jumaat MZ, Shukri AA, Obaydullah M, Huda MN, Hosen MA, et al.
    Polymers (Basel), 2016 Jul 19;8(7).
    PMID: 30974542 DOI: 10.3390/polym8070261
    This study investigates the flexural behaviour of reinforced concrete (RC) beams strengthened through the combined externally bonded and near-surface mounted (CEBNSM) technique. The externally bonded reinforcement (EBR) and near-surface mounted (NSM) techniques are popular strengthening solutions, although these methods often demonstrate premature debonding failure. The proposed CEBNSM technique increases the bond area of the concrete⁻carbon fibre reinforced polymer (CFRP) interface, which can delay the debonding failure. This technique is appropriate when any structure has a narrow cross-sectional width or is in need of additional flexural capacity that an individual technique or material cannot attain. An experimental test matrix was designed with one control and five strengthened RC beams to verify the performance of the proposed technique. The strengthening materials were CFRP bar as NSM reinforcement combined with CFRP fabric as EBR material. The test variables were the diameter of the NSM bars (8 and 10 mm), the thickness of the CFRP fabrics (one and two layers) and the U-wrap anchorage. The strengthened beams showed enhancement of ultimate load capacity, stiffness, cracking behaviour, and strain compatibility. The ultimate capacity of the CEBNSM-strengthened beams increased from 71% to 105% compared to that of the control beam. A simulation method based on the moment-rotation approach was also presented to predict the behaviour of CEBNSM-strengthened RC beams.
    Matched MeSH terms: Polymers
  10. Al-Asbahi BA, Haji Jumali MH, AlSalhi MS
    Polymers (Basel), 2016 Sep 06;8(9).
    PMID: 30974607 DOI: 10.3390/polym8090334
    The effect of TiO₂ nanoparticle (NP) content on the improvement of poly(9,9'-di-n-octylfluorenyl-2,7-diyl) (PFO)/Fluorol 7GA organic light emitting diode (OLED) performance is demonstrated here. The PFO/Fluorol 7GA blend with specific ratios of TiO₂ NPs was prepared via a solution blending method before being spin-coated onto an indium tin oxide (ITO) substrate to act as an emissive layer in OLEDs. A thin aluminum layer as top electrode was deposited onto the emissive layer using the electron beam chamber. Improvement electron injection from the cathode was achieved upon incorporation of TiO₂ NPs into the PFO/Fluorol 7GA blend, thus producing devices with intense luminance and lower turn-on voltage. The ITO/(PFO/Fluorol 7GA/TiO₂)/Al OLED device exhibited maximum electroluminescence intensity and luminance at 25 wt % of TiO₂ NPs, while maximum luminance efficiency was achieved with 15 wt % TiO₂ NP content. In addition, this work proved that the performance of the devices was strongly affected by the surface morphology, which in turn depended on the TiO₂ NP content.
  11. Ghaemi F, Abdullah LC, Tahir P
    Polymers (Basel), 2016 Nov 09;8(11).
    PMID: 30974671 DOI: 10.3390/polym8110381
    This paper focuses on the synthesis and mechanism of carbon nanospheres (CNS) coated with few- and multi-layered graphene (FLG, MLG). The graphitic carbon encapsulates the core/shell structure of the Ni/NiO nanoparticles via the chemical vapor deposition (CVD) method. The application of the resulting CNS and hybrids of CNS-FLG and CNS-MLG as reinforcement nanofillers in a polypropylene (PP) matrix were studied from the aspects of mechanical and thermal characteristics. In this research, to synthesize carbon nanostructures, nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O) and acetylene (C₂H₂) were used as the catalyst source and carbon source, respectively. Besides, the morphology, structure and graphitization of the resulting carbon nanostructures were investigated. On the other hand, the mechanisms of CNS growth and the synthesis of graphene sheets on the CNS surface were studied. Finally, the mechanical and thermal properties of the CNS/PP, CNS-FLG/PP, and CNS-MLG/PP composites were analyzed by applying tensile test and thermogravimetric analysis (TGA), respectively.
  12. Chan SY, Choo WS, Young DJ, Loh XJ
    Polymers (Basel), 2016 Nov 18;8(11).
    PMID: 30974681 DOI: 10.3390/polym8110404
    Pectin is an anionic, water-soluble polymer predominantly consisting of covalently 1,4-linked α-d-galacturonic acid units. This naturally occurring, renewable and biodegradable polymer is underutilized in polymer science due to its insolubility in organic solvents, which renders conventional polymerization methods impractical. To circumvent this problem, cerium-initiated radical polymerization was utilized to graft methoxy-poly(ethylene glycol) methacrylate (mPEGMA) onto pectin in water. The copolymers were characterized by ¹H nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA), and used in the formation of supramolecular hydrogels through the addition of α-cyclodextrin (α-CD) to induce crosslinking. These hydrogels possessed thixotropic properties; shear-thinning to liquid upon agitation but settling into gels at rest. In contrast to most of the other hydrogels produced through the use of poly(ethylene glycol) (PEG)-grafted polymers, the pectin-PEGMA/α-CD hydrogels were unaffected by temperature changes.
    Matched MeSH terms: Polymers
  13. Irfan SA, Razali R, KuShaari K, Mansor N
    Polymers (Basel), 2017 Mar 22;9(3).
    PMID: 30970794 DOI: 10.3390/polym9030111
    A mathematical model for the reaction-diffusion equation is developed to describe the nutrient release profiles and degradation of poly(lactic acid) (PLA)-coated controlled-release fertilizer. A multi-diffusion model that consists of coupled partial differential equations is used to study the diffusion and chemical reaction (autocatalytic degradation) simultaneously. The model is solved using an analytical-numerical method. Firstly, the model equation is transformed using the Laplace transformation as the Laplace transform cannot be inverted analytically. Numerical inversion of the Laplace transform is used by employing the Zakian method. The solution is useful in predicting the nutrient release profiles at various diffusivity, concentration of extraction medium, and reaction rates. It also helps in explaining the transformation of autocatalytic concentration in the coating material for various reaction rates, times of reaction, and reaction-multi diffusion. The solution is also applicable to the other biodegradable polymer-coated controlled-release fertilizers.
    Matched MeSH terms: Polymers
  14. Udenni Gunathilake TMS, Ching YC, Ching KY, Chuah CH, Abdullah LC
    Polymers (Basel), 2017 Apr 29;9(5).
    PMID: 30970839 DOI: 10.3390/polym9050160
    Extensive employment of biomaterials in the areas of biomedical and microbiological applications is considered to be of prime importance. As expected, oil based polymer materials were gradually replaced by natural or synthetic biopolymers due to their well-known intrinsic characteristics such as biodegradability, non-toxicity and biocompatibility. Literature on this subject was found to be expanding, especially in the areas of biomedical and microbiological applications. Introduction of porosity into a biomaterial broadens the scope of applications. In addition, increased porosity can have a beneficial effect for the applications which exploit their exceptional ability of loading, retaining and releasing of fluids. Different applications require a unique set of pore characteristics in the biopolymer matrix. Various pore morphologies have different characteristics and contribute different performances to the biopolymer matrix. Fabrication methods for bio-based porous materials more related to the choice of material. By choosing the appropriate combination of fabrication technique and biomaterial employment, one can obtain tunable pore characteristic to fulfill the requirements of desired application. In our previous review, we described the literature related to biopolymers and fabrication techniques of porous materials. This paper we will focus on the biomedical and microbiological applications of bio-based porous materials.
    Matched MeSH terms: Biopolymers; Polymers
  15. Haniffa MACM, Ching YC, Chuah CH, Kuan YC, Liu DS, Liou NS
    Polymers (Basel), 2017 May 01;9(5).
    PMID: 30970841 DOI: 10.3390/polym9050162
    Non-isocyanate polyurethane (NIPU) was prepared from Jatropha curcas oil (JCO) and its alkyd resin via curing with different diamines. The isocyanate-free approach is a green chemistry route, wherein carbon dioxide conversion plays a major role in NIPU preparation. Catalytic carbon dioxide fixation can be achieved through carbonation of epoxidized derivatives of JCO. In this study, 1,3-diaminopropane (DM) and isophorone diamine (IPDA) were used as curing agents separately. Cyclic carbonate conversion was catalyzed by tetrabutylammonium bromide. After epoxy conversion, carbonated JCO (CJCO) and carbonated alkyd resin (CC-AR) with carbonate contents of 24.9 and 20.2 wt %, respectively, were obtained. The molecular weight of CJCO and CC-AR were determined by gel permeation chromatography. JCO carbonates were cured with different amine contents. CJCO was blended with different weight ratios of CC-AR to improve its characteristics. The cured NIPU film was characterized by spectroscopic techniques, differential scanning calorimetry, and a universal testing machine. Field emission scanning electron microscopy was used to analyze the morphology of the NIPU film before and after solvent treatment. The solvent effects on the NIPU film interfacial surface were investigated with water, 30% ethanol, methyl ethyl ketone, 10% HCl, 10% NaCl, and 5% NaOH. NIPU based on CCJO and CC-AR (ratio of 1:3) with IPDA crosslink exhibits high glass transition temperature (44 °C), better solvent and chemical resistance, and Young's modulus (680 MPa) compared with the blend crosslinked with DM. Thus, this study showed that the presence of CC-AR in CJCO-based NIPU can improve the thermomechanical and chemical resistance performance of the NIPU film via a green technology approach.
  16. Jaganathan SK, Mani MP, Ismail AF, Ayyar M
    Polymers (Basel), 2017 May 04;9(5).
    PMID: 30970842 DOI: 10.3390/polym9050163
    The objective of this work is to characterize and investigate the blood compatibility of polyurethane (PU)/mustard oil composites fabricated using electrospinning technique. The fabricated scaffold was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and contact angle measurements. The activated partial thromboplastin time (APPT), prothrombin time (PT) and the hemolytic assay were done to investigate the blood compatibility of the developed composites. The SEM results revealed that the fiber diameter of the composites (761 ± 123 nm) was reduced compared to pristine PU control. The interaction between PU and mustard oil was confirmed by FTIR as evident through the shifting of peaks. The fabricated composites depicted hydrophobic behavior as insinuated by the increase in contact angle measurements. PU/mustard composites displayed improved crystallinity as confirmed by TGA. Atomic force micrographs suggested that developed PU/mustard oil composites showed an increase in the surface roughness (Ra) compared to pure PU. The Ra of pure PU was observed to be 723 nm but for the fabricated PU/mustard oil composite the Ra was found to be 1298 nm (Ra). The hemolytic index value for pure PU and fabricated composites was observed to be 2.73% and 1.15% indicating that developed composites showed a non-hemolytic behavior signifying the safety of the composites with red blood cells. Hence the newly developed composites with improved physicochemical and blood compatibility properties may be considered as a potential candidate for fabricating cardiac patches and grafts.
  17. Hosen MA, Alengaram UJ, Jumaat MZ, Sulong NHR, Darain KMU
    Polymers (Basel), 2017 May 19;9(5).
    PMID: 30970858 DOI: 10.3390/polym9050180
    Reinforced concrete (RC) structures require strengthening for numerous factors, such as increased load, modification of the structural systems, structural upgrade or errors in the design and construction stages. The side near-surface mounted (SNSM) strengthening technique with glass fiber-reinforced polymer (GFRP) bars is a relatively new emerging technique for enhancing the flexural capacities of existing RC elements. Nine RC rectangular beams were flexurally strengthened with this technique and tested under four-point bending loads until failure. The main goal of this study is to optimize the structural capacity of the RC beams by varying the amount of strengthening reinforcement and bond length. The experimental test results showed that strengthening with SNSM GFRP bars significantly enhanced the flexural responses of the specimens compared with the control specimen. The first cracking and ultimate loads, energy absorption capacities, ductility and stiffness were remarkably enhanced by the SNSM technique. It was also confirmed that the bond length of the strengthened reinforcement greatly influences the energy absorption capacities, ductility and stiffness. The effect of the bond length on these properties is more significant compared to the amount of strengthening reinforcement.
    Matched MeSH terms: Polymers
  18. Chieng BW, Ibrahim NA, Then YY, Loo YY
    Polymers (Basel), 2017 Jun 02;9(6).
    PMID: 30970882 DOI: 10.3390/polym9060204
    A renewable resource, epoxidized jatropha oil (EJO), was used as a green plasticizer and added to poly(lactic acid) (PLA). EJO was compounded into PLA at different contents. The addition of 3 wt % EJO to the PLA demonstrates significant improvement in flexibility, which leads to a percentage increase of about 7000% in elongation at break. This tensile result was confirmed by surface morphology analysis with clear proof of plastic deformation in EJO-plasticized PLA. EJO imparts a good heat stabilization effect. Thermal stability of PLA was enhanced upon addition of EJO, which is due to their good interaction and plasticizer dispersion within the PLA matrix. This EJO-plasticized PLA has wide applications in various industries, such as packaging of food and non-food products.
  19. Gaaz TS, Kadhum AAH, Michael PKA, Al-Amiery AA, Sulong AB, Nassir MH, et al.
    Polymers (Basel), 2017 Jun 06;9(6).
    PMID: 30970887 DOI: 10.3390/polym9060207
    A halloysite nanotubes⁻polyvinyl alcohol⁻polyvinylpyrrolidone (HNTs⁻PVA⁻PVP) composite has been investigated for a quite long time aiming at improving the physico⁻chemical characterization of HNTs. In this work, HNTs⁻PVA⁻PVP composite were prepared based on a unique procedure characterized by crosslinking two polymers with HNTs. The composite of two polymers were modified by treating HNTs with phosphoric acid (H₃PO₄) and by using malonic acid (MA) as a crosslinker. The composite was also treated by adding the dispersion agent sodium dodecyl sulfate (SDS). The HNTs⁻PVA⁻PVP composite shows better characteristics regarding agglomeration when HNTs is treated in advance by H₃PO₄. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), brunauer⁻emmett⁻teller (BET), size distribution, and atomic force microscopy (AFM) are used to characterize the physio-chemical properties of the composite. FTIR shows additional peaks at 2924.29, 1455.7, and 682.4 cm-1 compared to the neat HNTs due to adding MA. Despite that, the XRD spectra do not show a significant difference, the decrease in peak intensity could be attributed to the addition of semi-crystalline PVA and the amorphous PVP. The images taken by TEM and FESEM show the possible effects of MA on the morphology and internal feature of HNTs⁻PVA⁻PVP composite treated by MA by showing the deformation of the matrix. The BET surface area increased to 121.1 m²/g compared to the neat HNTs at 59.1 m²/g. This result, the second highest recorded result, is considered a breakthrough in enhancing the properties of HNTs⁻PVA⁻PVP composite, and treatment by MA crosslinking may attribute to the size and the number of the pores. The results from these techniques clearly showed that a significant change has occurred for treated HNTs⁻PVA⁻PVP composite where MA was added. The characterization of HNTs⁻PVA⁻PVP composite with and without treating HNTs and using crosslinker may lead to a better understanding of this new composites as a precursor to possible applications in the dentistry field.
    Matched MeSH terms: Polymers
  20. Rizwan M, Yahya R, Hassan A, Yar M, Azzahari AD, Selvanathan V, et al.
    Polymers (Basel), 2017 06 14;9(6).
    PMID: 30970902 DOI: 10.3390/polym9060225
    The authors wish to make a change to their published paper [1]. [...].
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