Flexural behavior of methyl methacrylate modified unsaturated polyester polymer concrete beams reinforced with glass‐fiber‐reinforced polymer sheets

This study represents the behavior of flexural test of methyl methacrylate modified unsaturated polyester polymer concrete beam reinforced with glass‐fiber‐reinforced polymer (GFRP) sheets. The failure mode, load–deflection, ductility index, and separation load predictions according to the GFRP reinforcement thickness were tested and analyzed. The failure mode was found to occur at the bonded surface of the specimen with 10 layers of GFRP reinforcement. For the load–deflection curve, as the reinforcement thickness of the GFRP sheet increased, the crack load and ultimate load greatly increased, and the ductility index was found to be the highest for the beam with the thickness of the GFRP sheet at 10 layers (6 mm) or 13 layers (7.3 mm). The calculated results of separation load were found to match only the experimental results of the specimens where debonding occurred. The reinforcement effect was found to be most excellent in the polymer concrete with 10 layers of GFRP sheet reinforcement. The appropriate reinforcement ratio for the GFRP concrete beam suggested by this study was a fiber‐reinforced‐plastic cross‐sectional ratio of 0.007–0.008 for a polymer concrete cross‐sectional ratio of 1 (width) : 1.5 (depth). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Flexural behavior of fiber and nanoparticle reinforced concrete at high temperatures

In this study, the flexural tests were conducted to investigate the effects of temperature, steel fiber, nano‐SiO₂, and nano‐CaCO₃ on flexural behavior of concrete at high temperatures. The load‐deflection curves of fiber and nanoparticle reinforced concrete (FNRC) were measured both at room and high temperatures. Test results show that the load‐deflection curves become flatter, and the flexural strength, peak deflection, and energy absorption capacity decrease seriously with the increase of temperature. Both steel fiber and nanoparticles could significantly improve the flexural behavior of the concrete at room and high temperatures. The energy absorption capacity of FNRC before the peak point increases with the increase of steel fiber volume fraction. The improvement of nano‐SiO₂ on flexural strength of FNRC at high temperature is better than that at room temperature, but the enhancement on energy absorption capacity is reverse. Nano‐SiO₂ is more effective than nano‐CaCO₃ in improving flexural behavior of concrete both at room and high temperatures.     

Mixed-mode fracture behavior of glass fiber reinforced polymer concrete

Fracture toughness of chopped strand glass fiber reinforced particle-filled polymer composite beams was investigated in Mode I and Mode III loading conditions using three-point bend tests. Effects of crack angles on fracture behavior were also studied. The specimens, which have inclined crack at an angle θ to the axis of the specimens, were used to carry out the tests. The specimens were tested with inclination angles 30°, 45°, 60° and 75°. The results are compared with the values of K_IC obtained using conventional (θ=90° ) specimens. In addition, J integrals were also determined. J_IC increases continuously with increasing in crack angle from θ=30° to θ=90°. In contrast, J_IIIC decreases with the crack inclination angle θ from 30° to 90°.     

Some aspects of the miscibility behavior of polyester/halogenated polymer blends

Glass transition temperature and depression in melting point methods are commonly used to determine the miscibility behavior of polymer/polymer blends, where at least one component of the mixture is semicrystalline. However, these methods often lead to ambiguous and even contradictory results, as can be shown by several examples. Furthermore, a comparison of the miscibility behavior of poly(vinyl chloride), poly(vinyl bromide), and poly(vinyl fluoride) with linear and branched polyesters indicates that small changes in the structure of the halogenated polymer and/or of the polyester lead to major changes in miscibility, indicating the subtle nature of the miscibility phenomenon and emphasizing difficulties in its control.     

Unsaturated polyester resins from poly(ethylene terephthalate) waste for polymer concrete

Depolymerization of poly(ethylene terephthalate), PET, textile waste was performed with a manganese acetate catalyst. Different ratios of diethylene glycol (DG) to propylene glycol (PG) were used for glycolysis. The weight ratio of PET to the glycol mixture was 1:0.65. The glycolyzed products were analyzed for hydroxyl value and the amount of free glycol. These glycolyzed products were reacted with mixtures of sebacic acid (SE) and maleic anhydride (MA) to prepare a series of unsaturated polyesters having different molecular weights. The molecular weights of the unsaturated polyesters produced were determined by the end group analysis. The obtained polyesters were dissolved in styrene (Sty) monomer and their curing behavior was investigated. Polymer concretes (PC) made with these resins were investigated for their compressive strength. The data revealed that the properties of the PC based on recycled PET are comparable to PC made from virgin materials. We concluded that recycling of PET waste may provide a potentially lower cost source of resin, and its recycling in PC will also help reduce an environmental problem.     

Characteristics of polyester polymer concrete using spherical aggregates from industrial by‐products

Despite its excellent physical and mechanical properties, polymer concrete has not been widely used owing to its much higher unit price than conventional portland cement concrete. To ensure the economic efficiency of polymer concrete, it is utmost important to reduce the use of polymer binder, which occupies most of the production cost of polymer concrete. Based on the experimental investigations, replacing filler (calcium carbonate) and fine aggregate (river sand) with fly ash and rapid‐cooled steel slag (RCSS), which are spherical materials obtainable from industrial by‐products, was found to be effective for improving the strength characteristics and durability as well as the cost efficiency of polymer concrete. The product developed in this study successfully reduced the demand for polymer binder by 21.3% compared to the conventional product, which in turn saved the total material costs by 18.5%. Although the use of RCSS showed performance degradation at an elevated temperature condition, considering typical temperature ranges that actual concrete infrastructures experience, it is expected that the polymer concrete using fly ash and RCSS will provide high‐level performances as construction and repair materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The swelling behavior of interpenetrating polymer networks composed of polyurethane and unsaturated polyester

The kinetics of swelling and the sorption performance were observed for the polymer compositions with interpenetrating polymer networks made up of polyurethane and unsaturated polyester during their exposure to chlorobenzene at 25°C. It was found that the rates for solvent transport and solvent absorption processes were controlled by the chemical composition of the formulation studied. On the basis of the observed swelling process, parameters could be assessed which were specific for the mass transfer process, i.e., diffusion coefficient, sorption coefficient, and permeability coefficient. Moreover, an attempt was made to evaluate structural parameters that describe topology of the obtained networks. It was found that the increasing share of polyurethane in the composition reduced crosslinking density in the polyester network that resulted in faster diffusion of the solvent and higher sorption capacity for the solvent. The higher the styrene content in the composition, the higher the crosslinking density in the system, and hence the diffusion of solvent and its sorption inside the polymer network was much more difficult. In the scanning electron microscope analysis of samples, which had been subjected to swelling, no leaching was observed for any phase present in the system, despite phase separation for both the components. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3511–3519, 2006     

Influences of metallic polymeric materials on the properties of fresh polyester and acrylic polymer concrete

To investigate the influences of three metallic polymeric materials in polyester and acrylic fresh polymer concretes (PCs), PC‐incorporated different levels of these materials have been investigated for their properties of fresh PC. The mix design was made and optimized for workability, strength, and economy, depending on the resin viscosity, the intended use, and the additional quantities of these polymeric materials. The properties investigated include workability, working time, and curing time of fresh PC. It is concluded that these polymeric materials offer the possibility of improving properties of polyester and acrylic fresh polymer concretes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Flexural performance of ring-type steel fiber-reinforced concrete

Steel fiber-reinforced concrete (SFRC) with randomly dispersed, short straight steel fibers hardly fails by fiber yielding, and the postpeak behavior is governed by mechanisms related to fiber pullout. It would be more desirable if more fracture energy could be consumed by fiber yielding at failure. It has been experimentally demonstrated in this research that SFRC with the ring-type steel fibers failed by more energy consuming mechanisms other than fiber pullout. Consequently, significant improvements in flexural toughness were obtained as compared to that of SFRC with conventional straight steel fibers.     

Viscoelastic behavior of a polyester resin concrete reinforced with nonmetallic bars under bending loads

This article deals with the study of a highly durable polyester polymer concrete reinforced with glass fiber polymer rebars. It describes the specific properties of the concrete, which were tested using different experimental techniques such as porosimetry, scanning electron microscopy, and petrography. Likewise, characterization on a macroscale was carried out to define the mechanical properties of the material (modulus of elasticity, stress–strain curve, ultimate strength, and bond). Having defined these properties, the article then presents a relatively simple calculation method to estimate the ultimate bearing capacity of beams under bending load, which is then verified by testing both beams and full-scale elements. Bearing in mind the viscoelastic nature of the polymer, several considerations are advanced on the identification of safety factors connected with permanent load (deferred deformations) and live load. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Effects of metallic monomer powders on the mechanical properties of hardened polyester and acrylic polymer concrete

To investigate the effects of three metallic monomer powders on polyester‐ and acrylic‐hardened polymer concretes, polymer concretes incorporating different levels of these materials were investigated for the properties of hardened polymer concrete. The mix design was made and optimized for workability and strength, depending on the resin viscosity, the intended use, and the additional quantities of these polymeric materials. The investigated properties included the compressive strength, flexural strength, and bond strength of hardened polymer concrete. It was concluded that these polymeric materials offer the possibility of improving the properties of polyester‐ and acrylic‐hardened polymer concretes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3106–3113, 2006     

Flexural behavior of bamboo-fiber-reinforced mortar laminates

This paper reports the flexural behavior of bamboo-fiber-reinforced mortar laminates. The laminate considered in this study is a sandwich plate combined with reformed bamboo plate and extruded fiber-reinforced mortar sheet. Due to its high strength to weight ratio, the reformed bamboo can remarkably strengthen the mortar and reduce the total weight of the laminate. Test results show that, for the laminates with reformed bamboo plate on the bottom as tensile layer and fiber-reinforced mortar sheet on the top as compressive layer, the flexural strength values can be improved to greater than 90 MPa.     

高黏度聚酯流变行为的研究

采用毛细管流变仪研究了高黏度聚酯(PET)的表观黏度及黏流活化能随温度(280～300℃)及剪切速率(20～104s-1)的变化。结果表明:高黏度PET熔体随着剪切速率的增加出现切力变稀现象,随着熔体温度升高,剪切速率对熔体的表观黏度的影响降低;高黏度PET的黏流活化能随着剪切速率的提高而降低;在温度为300℃,剪切速率为3 000 s-1时,高黏度PET熔体具有较好的流动性。     

Interfacial adhesion in polyester resin concrete

Silane coupling agents are widely used to improve the interfacial adhesion between the inorganic filler and the organic polymer matrix of polymer concretes. The mechanical properties of the concretes are also found to improve on the addition of silane coupling agents. This paper compares two methods of silane application; pretreatment of aggregates with silane and direct addition of silane to the resin, on the interfacial adhesion in polyester resin concrete for three different silanes. The effects of other parameters, such as the silane loading, predrying of aggregates before silane treatment, addition of CaCO₃ microfiller and pH of the silane treatment medium, are also investigated.     

聚酯类生物基聚合物的扩链改性

以丙二醇、丁二醇、癸二酸、丁二酸及衣康酸为原料合成了端羟基与端羧基并存的聚酯类生物基预聚物,以亚磷酸三苯酯(TPP)为扩链剂,研究了扩链温度、TPP添加量及数均分子量不同的预聚物等对扩链反应的影响。结果表明,在扩链温度为180℃、预聚体数均分子量为1.0×104左右的条件下,加入质量分数为15%的TPP,经扩链反应后,产物的数均分子量可达到4.8×104。红外光谱分析证实了扩链反应的发生;差示扫描量热分析结果显示扩链后产物的玻璃化转变温度有所上升,熔点有所下降;热重分析表明扩链后产物的热稳定性有所提高。     

Electrochemical behavior of coupled carbon fiber-reinforced polymer (CFRP) rods in concrete

This paper presents results on the electrochemical behavior of carbon fiber-reinforced polymer (CFRP) composite rods in contact with steel or epoxy coated steel bars in chloride-contaminated concrete. Twelve concrete prisms reinforced by CFRP rods electrically connected to plain or epoxy coated rebars were exposed to 80% humidity for 345 days. Four identical specimens that were not electrically connected served as controls. Measured galvanic currents densities were found to be as much as 100 A cm^–2, raising concerns about the degradation of both CFRP and steel. Electrochemical impedance spectroscopy (EIS) tests were performed to detect possible changes in the electrochemical parameters of CFRP due to galvanic interaction with active steel. Equivalent circuit simulations of the pre- and post-galvanic interaction of CFRP rods with active steel were also evaluated. EIS data indicated that the composite surface was altered so as to have porous electrode characteristics. Optical microscopy provided visible evidence of interface changes on the composite surface, supporting EIS data. The preliminary findings suggest that it would be unwise to permit CFRP to be directly in contact with steel in reinforcing or prestressing applications.     

聚酯纤维在沥青混凝土中的应用

分析了路用纤维性能的要求,比较了各种纤维的性能,确认了聚酯纤维是较适宜的纤维沥青混凝土加强材料。纤维沥青混凝土提高了沥青路面的高温抗车辙能力、低温抗裂性能、抗疲劳性能以及水稳定性能,有效地延长沥青路面的使用寿命。重点介绍了上海石油化工股份有限公司聚酯纤维产品金路丝在沥青混凝土中的应用情况。     

Flexural tests on epoxy-jointed precast prestressed concrete piles

The flexural behaviour of an epoxy-jointed precast prestressed concrete pile is discussed and compared with the performance of an unjointed pile and another pile with a welded joint. It is shown that the epoxy-jointed pile was capable of developing most of the ultimate capacity of the unjointed pile and had a stiffness comparable to the unjointed pile but higher than a welded jointed pile.     

Tensile behavior of clay-filled polyester composites

In this study, the tensile behavior of clay-filled unsaturated orthophthalic polyester composites was evaluated. Specifically, ultimate strength, yield strength, fracture strain, and Young's modulus of two composites with small but varying fractions of clay particulates were determined. Several predictive approaches were considered for correlation with experimental values. Only the Young's modulus of the composites could be predicted satisfactorily. The irregular shape and size distribution of clay particulates seriously complicate attempts to analytically model the mechanical behavior of filled composites. Microcracking response of the composites was evaluated using an acoustic emission (AE) technique. The addition of clay is shown to embrittle the composites and is confirmed by the AE count rate and amplitude distribution data. Scanning electron microscopy of the fracture surface shows evidence of flaw initiated fracture. This study provides an insight into the influence of clay particulates in altering the properties of a polyester matrix.     

Modifying polyester surfaces with incompatible polymer additives

Surface modification of amorphous PET in incompatible blends is demonstrated using fluorocarbon end-functional polystyrenes. Contact angles with water and decane were consistent with high levels of surface fluorocarbon, even for spin-cast films with no further processing required. Hydrophobicity and lipophobicity were further increased by annealing above the glass transition temperature. High resolution depth profiling using complementary ion beam analysis and specular neutron reflectometry has enabled accurate characterisation of the composition profile of the additive including the minimum in additive concentration found just below the surface enriched layer. This analysis quantified the very low compatibility between the modifying polymer and the amorphous PET and was consistent with the highly segregated nature of the adsorbing species and its sharp interface with the subphase. For these incompatible polymer blends, surfaces enriched with the surface active polymer could coexist at equilibrium with extremely low (∼0.4%) bulk loadings of the additive. This suggests that for thicker films at even lower additive concentrations than the minimum 1% that we studied, it may be possible to achieve efficient surface modification. However, at this concentration, the efficiency of surface modification is limited by the processing conditions. Finally we note that in higher loadings of surface active additive there is clear evidence for lateral phase separation into patterned domains of differing composition. The enhancement in surface properties is due to local reorganisation rather than bulk redistribution of the components within the film, as the composition versus depth distributions of the polymer blend components was observed to be relatively unaffected by annealing.