Based Polyol Research Papers - Academia.edu (original) (raw)

Objectives: This study is an attempt to enhance the properties of conventional PMMA denture material by incorporation of a polyfunctional polyol derived from palm oil by copolymerization with methyl methacrylate monomer to overcome the low fatigue resistance property of PMMA. Methods: A series of copolymerizations of palm oil polyol with MMA was performed in solution. The polyol was added from 40-20 , MMA from 20-40 , benzoyl peroxide as initiator was at 0.04 and toluene used as solvent was at 60 of the total weight. The copolymerization was carried out in a 500ml-round-bottom reaction flask, equipped with a magnetic stirrer, for 7.5 hour at 80ÂºC, in a water bath. The yield of each copolymerization obtained was recorded and the conversion was estimated gravimetrically. Later, the polymers acquired were analyzed by FTIR. Results: The copolymerizations have achieved conversions that ranged from 24 to 95, where the higher conversion was obtained when the reactant mixture contain higher amount of MMA. The reaction produced a clear color, light-weighted copolymer that has the potential to be developed as denture material. The evidence of incorporation of the polyol into PMMA was given by the FTIR measurements, by comparing the spectrum of the copolymer to the spectrum of PMMA and polyol. Evaluations of the mechanical properties were currently being carried out. Conclusion: The new copolymers have potential of being developed into new dental materials. The branching structure of the copolymer was expected to improve the impact strength of PMMA. In addition, the palm oil based polyol was made from natural sustainable material. This study was supported by E-Science fund, Grant No.: 03-0103-SF0190 and University of Malaya, Postgraduate Research Vote Grant No. : PS 079C/ 2007C and National Science Fellowship (NSF 2007/2008).

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- PMMA, Modification, Based Polyol, Dental Resin

Objectives:Biocompatibility is an important desirable property for a dental polymer and it can be achieved by utilizing more materials from natural sources. The flexural strength of an experimental polymer prepared from MMA monomer modified with palm-oil polyol was compared to two commercial resins,namely the Lucitone 199® (Dentsply Trubyte, USA) and Impact (Ivoclar Vivadent, Liechtenstein). Methods: The experimental polymer was prepared by copolymerizing MMA monomer and palm oil polyol. The resulting polymer was cast into a plate form and sectioned using a precision diamond saw (Buhler, Germany) to form 10 specimens of dimension, 65mm x 11mm x 5mm. These specimens were then polished to achieve a nominal dimension of 64mm x 10mm x 3.3mm. Another 10 specimens were prepared using Lucitone 199® and Impact according to the manufacturers' instructions and were polished by the same procedure. Their flexural strengths were determined using a three point bend test on an Instron Universal Testing Machine (Anytown, Australia)according to the procedure of test method ISO 1567. Data obtained was analysed using Oneway ANOVA (SPSS 12.0) at 95% confidence interval. Results: The mean flexural strength of Lucitone 199® was 127.39MPa (±16.54), Impact was 177.57MPa (±11.44) and experimental polymer was 51.62MPa (±4.21). Although the experimental polymer has exhibited higher flexural strength than PMMA homopolymer, it has lower flexural strength when compared to Lucitone 199® and Impact denture base resins, both of which were filler-reinforced materials. Conclusions:In this preliminary study, the experimental polymer contained a significant proportion of non-petroleum based materials derived from palm oil. Its lower flexural strength is expected to be enhanced and improved through the incorporation of reinforcing fillers or fibers in future work.

- by Noor Hayaty Abu Kasim
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- PMMA, Flexural Strength, Modified, Palm-oil

Polyol methods to synthesize nanoparticles and their arrays are ﬁrstly described.Magnetic nanoparticles selfassemble
under particular conditions into spherical superstructures, like CoNi nanoparticles, or planar structures with hexagonal ordering, like FePt nanoparticles.Particles and their arrays are structurally analysed by techniques like TEM, X-ray, etc. Magnetic characterization is ﬁrstly performed by VSM magnetomer as a function of the nanoparticles size paying particular attention to the transition from multidomain to single-domain structures.Later on, magnetic exchange coupling effects are discussed including the temperature dependence of magnetic parameters as coercive and exchange bias ﬁelds, as well as the inﬂuence of ﬁeld or zero-ﬁeld cooling processes. Finally, magnetic polymers consisting of magnetic nanoparticles embedded into PVC polymeric matrix are prepared and magnetically analysed.

Monodispersed spherical Co80Ni20 nanoparticles with diameters between 10 and 540 nm have been prepared by boiling liquid reduction of cobalt and nickel salts through a heterogeneous nucleation process (polyol process). All samples exhibit a core/shell structure with a ferromagnetic core surrounded by a surface layer consisting of antiferromagnetic oxides and organic matter. The ferromagnetic/antiferromagnetic interface, which arises from the core/shell structure, induces an exchange anisotropy at low temperature when the samples are subjected to a ﬁeld cooling process or to a zero ﬁeld cooling process starting from a remanent state. The shift of the hysteresis loops (exchange bias) and the increment of the coercive ﬁeld are consequences of the presence of this magnetic anisotropy. The effect of the particle size, the temperature and the cooling process on the magnetic behaviour of the samples has been analysed.

The goal of this study was to investigate the role of ethanol and temperature on the hydroxyl and carbonyl groups in biopolyol produced from hydrothermal liquefaction of loblolly pine (Pinus spp.) carried out at 250, 300, 350 and 390 °C for 30 min. Water and water/ethanol mixture (1/1, wt/wt) were used as liquefying solvent in the HTL experiments. HTL in water and water/ethanol is donated as W-HTL and W/E-HTL, respectively. It was found that 300 °C and water/ethanol solvent was the optimum liquefaction temperature and solvent, yielding up to 68.1 wt.% bio-oil and 2.4 wt.% solid residue. 31 P-NMR analysis showed that biopolyol produced by W-HTL was rich in phenolic OH while W/E-HTL produced more aliphatic OH rich biopolyols. Moreover, biopolyols with higher hydroxyl concentration were produced by W/E-HTL. Carbonyl groups were analyzed by 19 F-NMR, which showed that ethanol reduced the concentration of carbonyl groups.

- by Maria Auad
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- Water, Polymers, Multidisciplinary, Biomass to fuel conversion

A synthesis method based in the principles of the so-called polyol process has been developed to prepare Co nanocrystals of 5, 8 and 20 nm average diameter. The influence of stabilizers, as oleic and lauric acids, on the morphology and the self-assembled aggregates of the final Co nanocrystals has been analysed, as well as on their magnetic properties. Rather spherical Co nanoparticles were obtained using oleic and lauric acid, respectively, with 8 and 5 nm in diameter and narrow particle size distribution. The lauric acid, having a shorter chain length, seems to be more effective in coating the particles.