Recycling of polyurethane foam waste in the production of lightweight cement pastes and its irradiated polymer impregnated composites

This study aimed at using polyurethane foam waste in the production of lightweight white cement pastes by a partial replacement of white cement with different ratios of polyurethane foam waste (10%, 20%, 30%, and 40%) based on the weight of cement. The lightweight white cement pastes specimens in addition to conventional white cement paste were cured under tap water for 7 and 28 days. The physical, mechanical, and thermal properties were evaluated. The results showed that the specimens cured for 28 days achieved better properties as compared to the specimens cured for 7 days. Furthermore, at each curing age the specimens of lightweight white cement pastes showed relatively lower properties as compared to the conventional white cement paste and as the polyurethane waste content increased, the properties in terms of compressive strength and bulk density decreased while the total porosity percentage increased especially at higher ratios. On the other hand, the effects of styrene–butadiene rubber latex and irradiation dose on the properties of irradiated polymer impregnated lightweight white cement composites have been investigated. The results confirmed that the impregnation of the hardened lightweight white cement pastes with styrene–butadiene rubber latex and their exposure to different doses of gamma rays (50, 100, 150, and 200 kGy) showed a gradual improvement in the mechanical and physical properties up to 150 kGy and then started to decrease at 200 kGy. Characterization of some selected specimens was carried out by the studying of thermogravimetric analysis, scanning electron microscopy, and X‐ray diffraction. J. VINYL ADDIT. TECHNOL., 25:328–338, 2019. © 2019 Society of Plastics Engineers     

基于均匀设计试验法石材废粉再利用研究

为解决石材废料污染问题,利用花岗岩废粉和大理石废粉,结合水泥、石英砂、粉煤灰和木浆纤维,制备了经济实用、性能优异的水泥纤维压力板。运用均匀设计试验法和回归分析法,揭示了花岗岩废粉和大理石废粉对水泥纤维压力板抗折强度、抗冲击强度及导热系数的影响,并通过对比试验,分析了掺入石材废粉对水泥纤维压力板物理性能、水化产物及微观结构的影响。结果显示,适量掺入花岗岩废粉和大理石废粉可有效提高水泥纤维压力板的力学性能,当花岗岩废粉、大理石废粉与水泥的质量比分别为0.625和0.417时,不会对水泥纤维压力板的水化产物和微观结构形貌产生显著影响,可制备出符合要求并且经济适用的水泥纤维压力板。     

Morphology and Properties of Waterborne Polyurethane/CNT Nanocomposite Adhesives with Various Carboxyl Acid Salt Groups

Three series of waterborne polyurethane (WBPU)/carbon nanotube (CNT) nanocomposites were prepared, and their morphology and properties with various 2,2-dimethylol propionic acid (DMPA) and CNT contents were investigated. The CNTs were homogeneously dispersed up to the optimum content in WBPU/CNT nanocomposite films. The degree of homogeneous CNT dispersion increased with increasing DMPA content in WBPU/CNT nanocomposite films. The optimum CNT content showed maximum tensile strength, Young's modulus and adhesive strength of WBPU/CNT nanocomposite film. The optimum CNT contents for WBPU/CNT nanocomposite samples containing 3.61, 5.16 and 5.86 wt% DMPA were about 0.50, 1.00 and 1.50 wt%, respectively. The WBPU/CNT nanocomposite adhesive showed higher adhesive strength at moderately high temperatures (40/60/80/100°C) compared to conventional WBPU. The highest adhesive strength at moderately high temperatures was found with 5.86 wt% DMPA and 1.5 wt% CNT content.     

Replacement of hydroxyapatite from chicken eggshell waste for ceramic properties improvement

The chicken eggshell waste from food processing was synthesized as the hydroxyapatite for fluxing agent replacement in ceramic manufacturing. The main fluxing agents in Thailand ceramic manufacturing are natural potash feldspar (k-feldspar) and animal bone ash. To overcome the problems of inconstant properties and the lack of k-feldspar, the hydroxyapatite from chicken eggshell waste was selected as fluxing agent for the enhancement of the ceramic product. In this work, the hydroxyapatite with 0, 5, 10, and 15 wt% was replaced with the k-feldspar in the ceramic samples. The results revealed the physical and mechanical properties of the ceramic samples with various hydroxyapatite contents were investigated after heat treatment in the temperature range of 1000–1200 °C. The ceramic samples added with hydroxyapatite have higher linear shrinkage and bulk density as compared with the ceramic sample without hydroxyapatite. The apparent porosity and water absorption decreased to near zero after the heat treatment at a temperature of 1200 °C. Moreover, the results showed that the physical properties affected the mechanical properties improvement after the hydroxyapatite addition and heat treatment process.     

Flame retardancy,antifungal efficacies,and physical–mechanical properties for wood/polymer composites containing zinc borate

This work aimed to examine flame retardancy, antifungal performance and physical–mechanical properties for silane‐treated wood–polymer composites (WPCs) containing zinc borate (ZnB). ZnB with content from 0.0 to 7.0 wt% was added to WPCs, and silane‐treated wood contents were varied. The polymers used were poly(vinyl chloride) (PVC) and high‐density polyethylene (HDPE). The decay test was performed according to the European standard EN 113. Loweporus sp., a white‐rot fungus, was used for antifungal performance evaluation. Antifungal performance was observed to decrease with wood content. Incorporation of ZnB at 1.0 wt% significantly increased the antifungal performance of WPCs. ZnB content of greater than 1.0 wt% lowered the antifungal properties of WPCs. The results suggested that the wood/PVC composite exhibited better antifungal performance than the wood/HDPE composite. The addition of wood flour to PVC and HDPE decreased flame retardancy, whereas the incorporation of ZnB retained the flame retardancy. ZnB was found to be more appropriate for wood/PVC than wood/HDPE as a result of hydrogen chloride generated from the dehydrochlorination reaction of PVC. The results indicated that the addition of ZnB did not affect the physical‐mechanical properties of neat polymers and the composites. Copyright © 2016 John Wiley & Sons, Ltd.     

Influence of hydration on the mechanical,structural, thermal,and morphological properties of cement filled epoxy composites

Different loading of Portland cement (PC) (10, 20, 30, and 40 wt%) was used to produce epoxy-based polymer concrete. The optimum loading was used to prepare another sample using hydration in presence of air circulation. The polymer concretes were characterized in terms of mechanical, thermal, structural and morphological properties. The properties showed increasing trends after cement addition. Results showed that the tensile strength of the polymer concretes were improved by 37.2%, 115.5%, 165.9%, and 40.6% for loading of 10, 20, 30, and 40 wt% cement, respectively. In addition, the flexural strength of the polymer concretes was also enhanced and found maximum (175.3% higher) in 30 wt% concrete compared to neat epoxy. Other mechanical properties of the polymer concrete were also found increasing. Moreover, decomposition temperature was raised nearly 15°C for adding 30 wt% cement which was the maximum among the other polymer concretes. For the case of hydration in presence of air circulation, the prepared composite showed the highest tensile mechanical performance with improved surface topography. From the results, it was concluded that the addition of cement into the epoxy was very effective to produce polymer concretes.     

Evaluating recyclability of fly ash reinforced polyvinyl chloride foams

Using fly ash as a reinforcing filler can be very cost effective; however, the recycling of postconsumer products containing fly ash is of a considerable concern. In this study, the recycling of processed polyvinyl chloride (PVC) foam reinforced with fly ash was investigated by evaluating the effect of regrind content (up to 40 wt%) and fly ash content (up to 20 wt%) on the physical, mechanical, microstructural, and processing properties of the composites. Experimental results show an increase in the foam density with increasing regrind and fly ash contents. The melt viscosity increased with increasing the regrind concentration; however, it dropped with increasing the fly ash content. The tensile strength increased with increasing the regrind content, indicating a good degree of gelation in the composites. Meanwhile, the charpy impact strength of the composites decreased due to the high rigidity of fly ash particles. Dynamic mechanical analysis show that the storage modulus improved with both the addition and increasing the amount of regrind, which confirmed good stress transformation between the polymer foam matrix and the fly ash particles. The polymer matrix morphology, as was determined by scanning electron microscopy (SEM), confirmed uniform foam structure even with the addition of 40 wt% regrind in the virgin PVC. J. VINYL ADDIT. TECHNOL., 24:154–161, 2018. © 2016 Society of Plastics Engineers     

Investigation of the rheological and mechanical properties of a polystyrene‐polyisobutylene‐polystyrene triblock copolymer and its blends with polystyrene

The rheological and mechanical properties of a polystyrene‐polyisobutylene‐polystyrene (SIBS) block copolymer containing 30 wt% polystyrene (PS) and its blends with PS (SIBS/PS) were investigated. Atomic Force Microscopy (AFM) was used to visualize the nanostructured phase morphology of the SIBS, which is responsible for the mechanical strength of this thermoplastic rubber. The order‐disorder transition (ODT) for the SIBS block copolymer was found to be above 250°C. SIBS/PS blends with 10–30 wt% PS showed improved moduli and tensile strengths. Blends containing up to 40 wt% PS behaved as thermoplastic elastomers. In the region of linear viscoelasticity the blends revealed pronounced non‐Newtonian behavior and enhanced elasticity. This paper also reports the role of this styrenic block copolymer in the impact modification of PS.     

Recycling of aluminum dross and silica fume wastes for production of mullite-containing ceramics: Powder preparation,sinterability and properties

The improper disposal of industrial wastes causes environmental pollution so their recycling for fabrication of new products became an interesting research issue. In this work, sintered mullite-containing ceramics were prepared from aluminum dross and silica fume (up to 40 wt%) waste materials after sintering up to 1500 °C. Before sintering, the starting waste materials were converted into nano powders by mechanical milling alloying method up to 15 h. The obtained waste nano powders were investigated using different techniques as X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). On the other hand, phase identification by XRD, physical properties determination (bulk density and apparent porosity), microstructure by SEM, mechanical and electrical properties of sintered bodies were investigated. The results revealed that mullite phase was formed in higher amounts with increasing both sintering temperature (1500 °C) and silica fume content. At 1300 °C, amorphous mullite was formed in addition to the alumina phase. It is also noted that the apparent porosity and bulk density were reduced with increasing silica content. However, they exhibited opposite trend when the temperature increased from 1300 into 1500 °C. Moreover, with increasing the mullite content, the microhardness, compressive strength, Younges modulus and electrical conductivity were decreased and reached 10.2 GPa, 216.9 MPa, 119.7 GPa and 4.9 × 10 ^?12 S/m, respectively, for the sample that contained higher amount of mullite, while the fracture toughness was improved and reached to 3.44 MPa m^0.5.     

Preparation and characterization of eco-friendly and low-cost mullite-corundum foamed ceramics with low thermal conductivity

Mullite-corundum foamed ceramics were prepared by direct-foaming method using white clay and industrial alumina as raw materials, and calcium aluminate cement (CAC) as the binder. Effects of the calcium aluminate cement content on the phase compositions, microstructures and properties of the foamed ceramics were investigated through X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), etc. The results showed that with increasing the calcium aluminate cement content from 0 wt% to 8 wt%, the viscosities of the initial slurries decreased, the porosities of the samples improved, the thermal conductivities decreased, and the compressive strengths increased first and then decreased. The optimized sample with 4.0 wt% CAC content had a high porosity of 80.8%, a low bulk density of 0.56 g/cm³ and a low thermal conductivity of 0.232 W/(m·K) (800 °C). On the foundation of research results, the Gong equation (GE model) and a modified GE model were used to predict the thermal conductivity at 200 °C and 800 °C of the mullite-corundum foamed ceramics with different pore characteristics and phase compositions, respectively.     

Development and processing of flame retardant cellulose acetate compounds for foaming applications

Cellulose acetate (CA) is a bio-based polymeric material suitable to replace foamed polystyrene (PS) boards in applications for building insulation. Foam boards can be produced by extrusion foaming with physical blowing agents. In addition, the high heat deflection temperature and good mechanical properties (e.g., tensile and compression strength) of CA make it suitable for the injection molding of technical parts. In general, flame retardancy of foamed products is often required in building or electronic applications. This article presents the effects of various flame retardant (FR) additives, process settings, and the calibration of the foam board on flammability, foam morphology, and mechanical properties of extruded CA boards. Different formulations of FR additives and foaming agents were investigated regarding density and morphology of the foamed boards. Furthermore, investigations on foam behavior for foam injection molding with physical blowing agents were conducted. The foamed parts were characterized with regard to their flammability. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48863.     

The effect of ultra-high molecular weight polyethylene fiber on the mechanical properties of acrylic bone cement

The effects of the addition of ultra-high molecular weight polyethylene fiber (UHMWPE) on the mechanical properties of standard surgical Simplex-P radiopaque bone cement have been investigated. It was found that the tensile strength and tensile modulus were apparently not improved by the incorporation of UHMWPE in the acrylic bone cement. The results of bending strength and bending modulus indicated that a reinforcing effect is obtained at UHMWPE contents as low as 1 wt%, and then levelled off with increasing UHMWPE contents. When the UHMWPE contents as low as 2 wt%, the values of compressive strength and modulus seemed approximate the same; whereas the values of compressive strength and modulus decreased with increasing UHMWPE contents. From the results of dynamic mechanical analysis (DMA), the values of dynamic storage modulus of bone cement increased at UHMWPE fiber as low as 2 wt%, but beyond that UHMWPE content the value of the dynamic storage modulus decreased with increasing UHMWPE contents. The same results were also found for the dynamic loss modulus. When methyl methacrylate was grafted onto UHMWPE by plasma and UV irradiation treatment, it was found that by adding the treated UHMWPE fiber in acrylic bone cement had a significant reinforcing effect on the mechanical properties of bone cement.     

Polystyrene–organoclay nanocomposites prepared by melt intercalation,in situ,and masterbatch methods

In this study, polystyrene (PS)/montmorillonite nanocomposites were prepared by melt intercalation, in situ polymerization, and masterbatch methods. In the masterbatch method, as the first step, a high clay content composite of PS–organoclay (masterbatch) was prepared by in situ polymerization, and then the prepared masterbatch was diluted to desired compositions with commercial PS in a twin‐screw extruder. The structure and mechanical properties of the nanocomposites were examined. X‐ray diffraction (XRD) analysis showed that the d‐spacing of the in situ formed nanocomposites increased from 32.9 Å for the organoclay powder to 36.3 and 36.8 Å respectively in nanocomposites containing 0.73 and 1.6 wt% organoclay, indicating intercalation. However, the d‐spacing of the other prepared materials remained nearly unchanged when compared with pure organoclay powder. Thus, at these low clay contents, in situ formed nanocomposites showed the best improvement in mechanical properties including tensile, impact strength, and Young's modulus. In situ polymerization method did not prove to be efficient at high clay loadings in terms of intercalation and mechanical properties. At high clay loadings, the effects of the three methods in promoting mechanical properties were not significantly different from each other. POLYM. COMPOS., 27:249–255, 2006. © 2006 Society of Plastics Engineers     

Mechanical and morphological behavior in polystyrene based compatible polymer blends

Mechanical and morphological behavior of polystyrene (PS) based compatible polymer blend systems were studied using a tensile tester and scanning electron and optical microscopes. Four different binary compatible blend systems were employed and characterized: PS and poly (2,6-dimethyl 1,4-phenylene oxide) (PPO), PS and poly(vinylmethylether)(PVME), PS and poly(α-methyl styrene)(PαMS), and PPO and PαMS. The compositional dependence of the mechanical properties showed a synergistic effect with respect to modulus, but a negative deviation from the rule of mixtures relationship for strain at break. From the scanning electron microscope (SEM) observations, a deformation mode transition from crazing to crazing and shear banding occurs at ˜25 wt% PPO in the PS/PPO blends, as indicated by the patch and river patterns above this composition. In the PS/PVME blends, a similar transition was observed at >10 wt% PVME. The PS/PαMS blends showed brittle fracture regardless of composition. The PPO/PαMS blends showed a brittle fracture for a PαMS content >25 wt%. Optical microscope (OM) observations showed that blending of PS/PPO and PS/PVME resulted in a decrease of craze density and length as the PPO and PVME content was increased. PS/PαMS and PPO/PαMS blends showed few crazes, all of which were localized near the fracture surface. The mechanical and morphological behavior can be explained using models of intermolecular interactions and entanglement density in compatible blends, respectively. Overall the mechanical property and the consequent morphological behavior were similar to the effect of antiplasticization.     

Effects of cement content on the microstructural evolution and mechanical properties of cement-bonded corundum castables

The cement-bonded corundum castables are often subjected to great temperature gradient in the service process of purging plugs for refining ladle. The mechanical properties of such castables are of particular interest in the serviceability and the safety of purging plug, which are significantly influenced by the microstructures including the amount, size and morphology of materials. The reported cement contents in compounds of purging plugs are generally low or ultralow, which inevitably limits the adjustable range of the mechanical properties enhancement by regulating their microstructures. In the present research, a serial of comprehensive experiments have been carried out, including the high cement contents (10–15 wt%), so as to further understand the role of cement content on the microstructural evolution and mechanical properties of castables. It is found that the phase compositions and microstructure can be optimized through adjusting the cement content in corundum castables. When the cement content is below 10 wt%, the hexagonal flake CA₆ grains are platelet-shaped both in the matrix and at the border of the aggregates, their amount and size increase and distributions are more uniformly with cement content. When the cement content is above 10 wt%, small amount of granular crystals CA₂ are detected in matrix, and CA₆ crystals transform to equiaxial morphologies after cement content of 10 wt%. This research also provides quantitative relationship between the mechanical properties of the castables and the cement content. Castables with cement content of 10 wt% contain most hexagonal flake CA₆ crystals, so that they have the highest CMOR and HMOR after heating at 1600 °C. However, CMOR decreases after cement content of 10 wt% due to the porosity and volumetric expansion from the formation of in-situ CA₆ and CA₂.     

Effects of two types of clay on physical and mechanical properties of poly(lactic acid)/wood flour composites at various wood flour contents

To investigate the effects of two types of clay, namely, Na‐montmorillonite (Na‐MMT) and organic‐montmorillonite (OMMT), on poly(lactic acid) (PLA)/wood flour (WF) composites, some physical and mechanical properties including the water sorption, thickness swelling, flexural modulus of rupture (MOR), and modulus of elasticity (MOE) of PLA/WF composites at different WF contents of 0, 20, 40, and 60 wt% were tested in this study. The results showed that: (1) the 24 h water uptake and thickness swelling increased and the flexural MOR and crystallinity decreased with the increasing WF content, whereas the flexural MOE of the composites increased with WF content up to 40 wt% but decreased sharply at WF content of 60 wt%; (2) the addition of Na‐MMT slightly increased the 24 h water uptake as well as the thickness swelling rate below 40 wt%, whereas OMMT reduced the thickness swelling at higher WF contents (40, 60 wt%) although it showed little effect on 24 h water uptake; (3) both Na‐MMT and OMMT could improve the flexural MOR and MOE of PLA/WF composite at WF contents below 40 wt%, and OMMT resulted in more obvious improvement than Na‐MMT. However, they both showed negative effect at WF content of 60 wt%; (4) XRD and FT‐Raman analysis suggested that clays would be attached more on the surface of the WF rather than diffused in the PLA matrix at a higher WF content (60 wt%); (5) SEM analysis proved that the interfacial adhesion of PLA and WF became poorer at WF content above 40 wt%, whereas it could be improved by OMMT modified. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Glass transition behavior of polypropylene/polystyrene/styrene-ethylene-propylene block copolymer blends

Summary The glass transition behavior of ternary blends of polypropylene (PP), polystyrene (PS) and styrene-ethylene-propylene-styrene block copolymer (SEPS) was investigated. The blends were prepared by an internal mixer, and their dynamic mechanical properties and morphology were measured. The blends showed phase inversion at around 75wt% PS composition. The glass transition temperature (T_g) of the PP phase shifted to lower temperature as the PS contents were increased in PP/PS binary blends, probably due to the mismatch of thermal expansion coefficients between two components. As the SEPS copolymer contents were increased, the T_g's of the PP phase in the blends increased. In particular, the large increase in T_g of the PP phase was observed in the PP/PS (25/75) blends where the phase inversion takes place. Received: 2 February 1998/Revised version: 24 March 1998/Accepted: 13 April 1998     

Introductory behavior of rubber concrete

This article introduces a new type of concrete, the so‐called rubber concrete, and thereupon presents a way of modification of waste rubber to construction articles. The conventional cement concrete is made by mixing cement with sand and pebbles, but the rubber concrete proposed here virtually excludes cement completely. The manufacturing process of rubber concrete can be divided into two methods, which are designated for dry and wet processes, but this article focused just on the dry process. The physical properties of rubber composite increased with the silane treatment of added aggregates, but the volume of the aggregate might not be a critical factor affecting the compressive strength in the range of the aggregate contents used in this study, that is, the interfacial adhesion between the matrix rubber and the aggregates was a key factor to improve the mechanical properties of rubber concrete. The compressive strength of rubber concrete was about 89 MPa and the Poisson's ratio, which is the ratio of compressive‐to‐tensile strength, was 5.5%. From the viewpoint of the compressive strength and the Poisson's ratio, rubber concrete had better properties than those of conventional cement concrete. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 35–40, 1999     

In situ compatibilization of polystyrene/polyolefin elastomer blends by the Friedel–Crafts alkylation reaction

Blends of polystyrene (PS) with polyolefin elastomer (POE) were prepared by a reactive extrusion method. In order to increase the compatibility of the two blending components, a Lewis acid catalyst, aluminium chloride (AlCl₃), was adopted to initiate the Friedel–Crafts alkylation reaction. Fourier‐transform infrared (FTIR) spectra of the PS/POE/AlCl₃ blends extracted with butanone verified the graft structure between the PS and POE. Because the in situ generated PS‐graft‐POE copolymers acted as compatibilizers, the mechanical properties of PS/POE blends were greatly improved. For example, after compatibilization, the Charpy impact strength of an 80/20 (wt%) PS/POE blend was increased from 6.29 to 8.50 kJ m^?2. Scanning electron microscopy (SEM) showed that the size of the droplets decreased from 9–10 µm to less than 2 µm with the addition of AlCl₃. Gel permeation chromatography (GPC) showed competition between the grafting reaction and the degradation of blending components in the presence of AlCl₃. Copyright © 2005 Society of Chemical Industry     

Use of polystyrene nanoparticles synthesized by differential microemulsion polymerization for property improvement of (vinyl acetate)‐ethylene copolymer

The nanolatex of polystyrene (PS) synthesized by differential microemulsion polymerization was blended with (vinyl acetate)‐ethylene (VAE) copolymer emulsion at VAE/PS dry weight ratios of 90/10, 80/20, 70/30, and 60/40. This technique provided a well dispersion of PS nanoparticles in the blends without any phase separation or flocculation. The blended emulsions were cast into thin sheet for further characterizations. It was found that the tensile strength, Young's modulus, dynamic mechanical properties, and thermal stability at 50% degradation of VAE were increased by the addition of an appropriate amount (20, 30, 40, and 40 wt%, respectively) of the PS nanoparticles, whereas the elongation at break deteriorated. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers