Papers by Keyword: Polyester

Abstract: In this work, a series of novel polymer gel electrolytes with 3D network as ion channels were extensively investigated. Four type polyesters, which are poly (glutaric acid pentaerythritol ester) (PGAPE), poly (adipic acid pentaerythritol ester) (PAAPE), poly (suberic acid pentaerythritol ester) (PSAPE) and poly (pentanedioic acid pentaerythritol ester) (PPAPE), were successfully developed for quasi-solid-state dye-sensitized solar cells (DSCs) with a maximum PCE of 5.32% under AM 1.5 illumination. Photoelectrochemical measurements of the DSCs were conducted by using electrochemical workstation. The present findings indicate that the 3D network structure of polyesters can facilitate the ionic transport and improve the PCE of the DSCs.

Abstract: Polymer matrix composites are widely applied for the manufacturing of components employed in hostile environments to increase the service life and sometimes at a later stage for the reclamation of worn out parts. Every decade, numerous materials and techniques are being introduced and developed for the effective protection of low cost bulk materials out of which the fabrication of components could be done. Among such techniques hand layup, matched die mould methods, contact mould methods, filament winding and pultrusion methods has being employed increasingly in the process industries which has several significant advantages over other processes. It has become a process of its reliability, better process control, ease of use, good surface finish and closeness of dimensions. One among the method matched die mould method was selected as the process of preparation of the composite plate in the presented work. However, there are some inherent problems with control of resin flow, application of high temperature for curing during fabrication process. To address those main problems, a systematic investigation was carried out. The selected material is natural plant fibre available in abundant called “Crotalaria juncea” and is being employed as a green manuring plant in agriculture. In the investigation, the fibre is taken in two different forms of random and woven orientations and plate fabrication is done with unsaturated polyester resin as the matrix. The investigation is on woven orientation of biaxial, biaxially stitched and unidirectional woven types were done using the fibre to the size of the plate to be fabricated. Woven fibres of these three types were done at fibre design centre, Kerala. It was found that the fabrication could be done by placing two layer and three layer of the woven mat alone. So for the three woven types, two layer and three layer plates were fabricated to give about six plates in total. Here again to arrive at a closeness value for each combination, three plates were fabricated and the average value is got by testing. Tensile, flexural, impact and shear testing was done on all the plates as per ASTM standards and the responses were noted and plots were drawn and studied for the orientation for which the material possessed best property. The second part of the study was, with the experimental results got from the woven orientation, analysis was done by ANSYS and LS-DYNA software for the mechanical property and the responses got, was matching with the experimental testing methods and found that both the results were nearly the same thereby optimizing the results achieved. This is presented in detail in the forth coming chapters. The studies revealed that the fibre parameters taken had a significant influence on the mechanical properties. It was found that at a particular weight fraction the mechanical properties achieved the highest values in case of random orientation and particular woven orientations in case woven types. The increase in layers also had an influence over the property of the material. This composite prepared also initiates us in preparing newer composites with existing natural fibers, which haven’t been yet explored and which can reduce the cost. This gives way also in preparation of the same and releasing a newer variety of material to the Engineering industry which can be suited for some required application.

Abstract: Epoxy/amine-coated polyester triangular bar composites were fabricated and exposed to 5 wt% hydrochloric acid (HCl) solution at 40 °C. The weight loss characteristics of pre-exposed composites in heated air at 40 °C under forced convection were studied as function of size, spacing, alignment, and orientation of triangular bars. The diffusion coefficient of composites during desorption increases when the bars are oriented flat and are aligned in parallel. The same result is observed when the size of triangular bars is increased, and when spacing between bars is decreased. These results are attributed to the presence of epoxy/polyester interphase regions, which are more accessible when the triangular bars are oriented flat and aligned parallel, have larger size, and have smaller spacing. These interphase regions are preferred conduits of water during desorption of composites. The diffusion coefficients of composites being higher than the values of epoxy and polyester resins further confirm the effect of interphase regions. Among the factors, orientation of triangular bars has the highest influence on the desorption behavior of epoxy composites.

Abstract: Natural zeolite, an abundant clay with porous solids based on silica, is modified with amine salt and surfactant, and incorporated as filler for polyester to produce modified zeolite/polyester (MZP) composite. A general factorial design of experiment is implemented with two factors (type of amine salt and type of surfactant) varied at three levels each. The amine salts are tetra- (TDA), hexa-, and octadecyl dimethylamine chloride while surfactants are stearic acid (SA), glycerol monostearate, and cocamide diethanolamine (CDEA). Water sorption and flexural testing are performed on MZPs. Results show that natural zeolite treated with SA exhibits improved hydrophobicity of MZPs, resulting to lower water uptake as compared to untreated natural zeolite. However, water sorption in MZPs is higher than in pure polyester due to difference in hydrophobicity. Flexural modulus of MZP is highest using TDA + CDEA due to enhanced filler-to-matrix compatibility. Meanwhile, break stress is highest for untreated zeolite filler due to the high stress resistance of rigid natural zeolite. Analysis of variance shows water sorption to be significantly affected by the type of surfactant, while break stress is significantly higher using amine salt with shorter chain length.

Abstract: The effect of alkali treatment and nanoclay addition on the mechanical properties and water absorption behavior of rice husk particle (RHP) reinforced unsaturated polyester (UP) composites was investigated. Thermogravimetric analysis (TGA) indicated that the alkali treatment removed most of the hemicellulose and impurities from the RHP with the tensile strength, tensile modulus, flexural strength and flexural modulus of the resulting composites being improved by alkali treatment. The results indicated that the 5% sodium hydroxide concentration had the optimum performance on mechanical strength and water absorption resistance. Furthermore, the influence of nanoclay addition (1, 3 and 5 wt%) on the properties of optimum alkali treated RHP-UP composites was investigated with the lowest content (1 wt%) of nanoclay showing the highest mechanical performance. However, further addition of nanoclay improved the moisture absorption resistance of the composites. Good interface bonding between the filler and matrix was observed from scanning electron micrographs for the optimum RHP alkali treated and nanoclay dispersed RHP-UP composites.

Abstract: Sorption and degradation characteristics of epoxy composites reinforced with amine-coated polyester triangular bars in acid environment were studied. The following aspects of amine-coated triangular bars were varied during preparation of epoxy composites: orientation (flat or pointed), alignment (parallel or staggered), spacing (1 or 5 mm), and size (5 or 7 mm). Composites were tested using a one-side acid exposure test in 5 wt% hydrochloric (HCl) acid solution at 40°C for 308 h. Weight change curves of composites with pointed orientation show continuous sorption of acid solution with square root of time, while composites with flat orientation display an initial increase in weight followed by continuous weight loss. This can be attributed to the large interfacial area of triangular bars exposed to diffusing acid in flat orientation. Since the bars are amine-coated, the acid preferentially diffuses in the interfacial region, resulting to early degradation of composite. The following parameters were measured from the weight curves for data analysis: initial sorption rate (% - h^-0.5), maximum weight change during sorption (%), and weight loss due to degradation (%). Analysis of variance (ANOVA) shows maximum weight change and weight loss due to degradation of epoxy composites are significantly affected by orientation and spacing.

Abstract: To recycle the solid wastes, the hydrotalcite-like compounds (HTLcs) were prepared from the magnesia flue gas desulfurization residues (MFGDR). The HTLcs as prepared and the products from degradation of Poly (ethylene terephthalate) (PET) were characterized by thermogravimetric analysis (TG) , x-ray powder diffraction (XRD) , fourier transform infrared spectrometer (FTIR) and differential scanning calorimetry (DSC) methods. Effects of calcining temperature and alkaline of solution on the structure and performance of HTLcs were studied. The main product of alcoholysis of PET was bis-hydroxyethyl terephthalate (BHET). The catalyst shows a potential application in solid waste treatment and recycle.

Abstract: In this study, four poly (ester-block-ether) copolymers were synthesized via the macromolecular transesterification method from different hydrophobic polyester segments prepared from precursors, dimethyl terephthalate (DMT), ethylene glycol (EG), dimethyl-5-hydroxyisophthalate (DHIP) and neopentyl glycol (NPG), and hydrophilic polyether, polyethylene glycol (PEG) or polyetheramine (PEA). The hydrolysis-resistance performance at alkaline condition and hydrophilicity of these four synthetic poly (ester-block-ether) copolymers were characterized by hydrolysis degree and water solubility with Nuclear Magnetic Resonance (NMR) and UV-Absorption Spectroscopy. The results showed that the hydrolysis degree and water solubility of poly (ester-block-ether) copolymers were mainly dominated by the molecular components, the molecular weights of polyester and polyether chains, and the connecting bonds between polyester and hydrophilic chains. The hydrolysis degree was listed from high to low: P(DHIP-NPG)-b-PEA, P(DMT-NPG)-b-PEA, P(DMT-EG)-b-PEA, then P(DMT-EG)-b-PEG. The P(DHIP-NPG)-b-PEA copolymer possesses the best hydrolysis-resistance performance, the hydrolysis degree of which reached only 4.1% after hydrolysis for 14 days, meanwhile, it showed excellent adsorption property on polyester fabrics and the surfaces of the treated fabrics exhibited well hydrophilicity. This study provides a light to explore novel poly (ester-block-ether) copolymers with well hydrolysis-resistance performance and high hydrophilicity through precisely constructing their molecular components, and further extend their potential applications in special auxiliaries and intermediates.

Abstract: This study investigated the mechanical behavior of the treated and untreated kenaf with different matrix resin (epoxy and polyester) using the tensile and low velocity test. The long kenaf fibre was treated with 6% of sodium hydroxide (NaOH) solution for twelve hours in room temperature. The tensile properties of composites at different weight percentage (10,15,20 and 25%) were studied by using Instron Universal Testing Machine according to the standard ASTM D638. Impact test was conducted using an instrumented drop tower device at 10J incident energy level according to the standard ASTM D3763. The results of the study indicated that the epoxy resin reinforced with treated kenaf fibre exhibited higher tensile properties. On the other hand, the impact properties of polyester resin reinforced with treated kenaf fibre show better matrix bonding compared to those with epoxy resin matrices.

Abstract: This paper reports on the application of natural dyes on polyester fabric. Melastoma malabathricum l. was extracted using conventional method of boiling for an hour. Plain lightweight polyester fabric was treated with sodium hydroxide as an alkaline treatment and Chitosan prior to dyeing in an attempt to increase the dye uptake. The dye extract of Melastoma malabathricum l. was applied on the polyester fabric at 85°C for an hour by exhaustion dyeing and 40 minutes for ultrasound dyeing. The colors of the dyed fabrics were measured using colour spectrophotometer and evaluated for washfastness. Ultrasound dyeing gave deeper colour shades to the fabric even though dyeing was conducted at lower temperature for 40 minutes. The alkaline treated fabrics dyed using ultrasound gave lower value of L* which indicate higher dye uptake and darker colour. The ratings for colourfastness to washing were between 4/5 to 5.