Combined effect of zeolite and boric acid on thermal behavior of epoxy composites

The particles of natural zeolite in combination with boric acid were incorporated into the epoxy resin ED-20 in order to improve the thermal stability of epoxy polymer. Epoxy resin was cured using polyethylenepolyamine. Characterization of the epoxy composites was carried out by using Fourier transform infrared spectrometry, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under flow of air and argon. The thermal behavior of the zeolite/boric acid-based epoxy composites (total percentage 15 mass%) were compared with that of 15 mass% boric acid-based epoxy system and the neat epoxy resin. TG and DSC results revealed that the combination of 5 mass% zeolite and 10 mass% boric acid significantly increased the mid-point temperature and residue, and decreased the maximum decomposition rate of the epoxy composites at the heating.     

Effects of synthetic and natural zeolites on morphology and thermal degradation of poly(lactic acid) composites

Poly(lactic acid) (PLA) composites containing 5 wt% synthetic (type 4A) and natural (chabazite) zeolites were prepared using extrusion/injection molding. Morphological, structural, and thermal properties of composites were investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). DSC results revealed that the glass transition and melting temperatures were not significantly changed; however, the incorporation of both type 4A and chabazite zeolites enhanced the nucleation of PLA crystallites as well as increased the percent crystallinity. Thermal degradation properties of PLA and PLA/zeolite composites were studied by non-isothermal thermogravimetric analysis (TGA) in nitrogen atmosphere. TGA results showed that at temperatures above 300 °C, PLA/type 4A synthetic zeolite composites were thermally decomposed more easily than the PLA and PLA/chabazite natural zeolite composites. The apparent activation energies of thermal degradation of PLA and PLA/zeolites composites estimated using both the Flynn-Wall-Ozawa and Kissinger methods followed the same order: PLA/type 4A < PLA/chabazite < PLA.     

Influence of surface modification of fillers and polymer on flammability and tensile behaviour of polypropylene-composites

An intumescent system consisting of ammonium polyphosphate (APP) as an acid source and blowing agent, pentaerythritol (PER) as a carbonific agent and natural zeolite (clinoptilolite, Gördes II) as a synergistic agent was used in this study to enhance flame retardancy of polypropylene (FR-PP). Zeolite was incorporated into flame retardant formulation at four different concentrations (1, 2, 5, and 10 wt%) to investigate synergism with the flame retardant materials. Filler content was fixed at 30 wt% of total amounts of flame retardant PP composites. Zeolite and APP were treated with two different coupling agents namely, 3-(trimethoxysilyl)-1-propanethiol and (3-aminopropyl)-triethoxysilane for investigation of the influence of surface treatments on mechanical properties and flame retardant performance of composites. Maleic anhydride grafted polypropylene (MAPP) was used for making polypropylene hydrophilic. Flammability of FR-PP composites was measured by the determination of limiting oxygen index (LOI). The LOI values reached to a maximum value of 41% for mercapto silane treated APP:PER (2:1) PP composite containing 5 wt% zeolite. The tensile strength of composites was increased by the addition of MAPP and elongation at break of composites was increased with silane treatments.     

Natural rubber composites reinforced with basic magnesium oxysulfate whiskers: Processing and ultraviolet resistance/flame retardant properties

The Magnesium sulfate whiskers (MOSw) were first modified by Stearic acid or Si69, and Natural rubber (NR)/modified-MOSw composites were prepared by blending the modified-MOSw with natural rubber latex. By adding modified-MOS_W into NR, the mechanical properties, the anti-ultraviolet aging property, flammability, and thermal stability of composites were improved obviously. The mechanical properties, crosslink density and thermal stability of composites reach the highest value at 4 wt% Si69-MOS_W. The composite with MOS_W addtion had a higher retention rate after ultraviolet irradiation and the MOS_W could improve the anti-ultraviolet aging property of rubber matrix. The modified MOS_W can effectively improve the oxygen index and the flame retardant grade of rubber composites.     

The effect of triethyl citrate on the dispersibility and water vapor sorption behavior of polylactic acid/zeolite composites

The aim of this study was to investigate the water vapor adsorption behavior and mechanical properties of poly (lactic acid) (PLA)/zeolite (5, 10, or 15 phr) composites prepared with triethyl citrate (TEC; 20 phr) via a melting process. TEC was used to improve the flexibility of the PLA and the dispersibility of the zeolite in TEC-zeolite suspensions that were ultra-sonicated. It was found that zeolite was uniformly dispersed in the PLA matrix, and the interfacial adhesion between the PLA matrix and zeolite was enhanced by TEC. In addition, the tensile strengths and Young's modulus of the composites improved with increasing zeolite content. The PLA/zeolite composites prepared with TEC had increased water vapor permeability and contact angles compared to neat PLA and standard PLA/zeolite due to the presence of TEC. In particular, TEC accelerated the hydrolysis of the PLA surface in a high humidity environment, resulting in an improvement in water vapor sorption capacity. At the same zeolite content of 15 phr, the equilibrium moisture content (EMC) values of PLA/zeolite films prepared with TEC increased by up to 39.25 mg/g whereas those prepared without TEC only increased by up to 24.33 mg/g. The results suggest the possibility of applying PLA/zeolite films prepared with TEC as a flexible active packaging material.     

Effects of modified multi-walled carbon nanotubes on the curing behavior and thermal stability of boron phenolic resin

One kind of boron phenolic resin (BPR) was prepared from the solvent-less reaction of resoles with boric acid. X-ray photoelectron spectroscopy (XPS) showed that the reaction degree of boric acid was 83.8%. Multi-walled carbon nanotubes (MWCNTs) were modified by nitric acid, 4,4′-Diaminodiphenyl methane and boric acid. The effect of modification was determined by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) techniques and XPS. The cure kinetics and thermal behavior of BPR and modified multi-walled carbon nanotubes (m-MWCNTs)/BPR were studied. It was found that the curing apparent activation energy (E_a) decreased with the increasing amount of m-MWCNTs. But there was no obvious change in the orders of curing reactions. The results of TGA showed that 1.0 wt% of the m-MWCNTs could increase the thermal decomposition temperature (T_d) and the char yield of m-MWCNTs/BPR nanocomposites by 36.7 °C and 6.2%. These critical enhancements will definitely help to attract more researches on this area.     

Industrial cutting waste granite dust reinforced cardanol benzoxazine/epoxy resin hybrid composites for high-voltage electrical insulation applications

An attempt has been made to develop hybrid composites from benzoxazine monomer (C-ddm) hybridized with DGEBA epoxy resin (EP) and reinforced with varying weight percentages (20 wt%, 40 wt%, 60 wt%, 80 wt% and 100 wt%) of glycidoxypropyltrimethoxy- silane (GPTMS) functionalized granite dust (GD) obtained from industrial granite cutting and polishing process in order to utilize them for electrical insulation applications. The thermal stability of granite dust reinforced poly(EP-co-C-ddm) composites was studied by TGA analysis. Among the composites samples studied, 100 wt% GD reinforced poly(EP-co-C-ddm) composites possess better thermal stability than that of other neat matrices and composites. Among the composites prepared using varying weight percentages of functionalized GD reinforcement, it was observed that 80 wt% GD reinforced poly(EP-co-C-ddm) composites possesses better hydrophobic character than that of other neat matrices and composites. The value of LOI calculated for neat matrix (poly[EP-co-C-ddm]) and 20 wt%, 40 wt%, 60 wt%, 80 wt% and 100 wt% GD reinforced composites was found to be 22, 28, 34, 40, 43 and 45 respectively. The 80 wt% GD reinforced poly(EP-co-C-ddm) composites possess the higher values of tensile strength and flexural strength of 47 MPa and 140 MPa, respectively than those of their samples. The values of electrical surface resistivity and electrical volume resistivity of all the neat matrices and GD reinforced polybenzoxazine composites were found to be in the order of 10¹² and 10¹³ respectively. The values of dielectric strength obtained from break down voltage (BDV) for neat matrix [poly(EP-co-C-ddm)] and 20 wt%, 40 wt%, 60 wt%, 80 wt% and 100 wt% of GD reinforced poly(EP-co-C-ddm) composites are 15.0, 15.5, 16.5, 17.0, 17.0 and 17.0 kV/mm, respectively. Data obtained from thermal stability, hydrophobic behavior and dielectric studies it was inferred that the hybrid polymer composites developed in the present work can be conveniently used in the form insulators, sealants, adhesives and matrices where application demands at high-performance industrial and engineering applications.     

On the use of plant cellulose nanowhiskers to enhance the barrier properties of polylactic acid

Polylactic acid (PLA) nanocomposites were prepared using cellulose nanowhiskers (CNW) as a reinforcing element in order to asses the value of this filler to reduce the gas and vapour permeability of the biopolyester matrix. The nanocomposites were prepared by incorporating 1, 2, 3 and 5 wt% of the CNW into the PLA matrix by a chloroform solution casting method. The morphology, thermal and mechanical behaviour and permeability of the films were investigated. The CNW prepared by acid hydrolysis of highly purified alpha cellulose microfibers, resulted in nanofibers of 60–160 nm in length and of 10–20 nm in thickness. The results indicated that the nanofiller was well dispersed in the PLA matrix, did not impair the thermal stability of this but induced the formation of some crystallinity, most likely transcrystallinity. CNW prepared by freeze drying exhibited in the nanocomposites better morphology and properties than their solvent exchanged counterparts. Interestingly, the water permeability of nanocomposites of PLA decreased with the addition of CNW prepared by freeze drying by up to 82% and the oxygen permeability by up to 90%. Optimum barrier enhancement was found for composites containing loadings of CNW below 3 wt%. Typical modelling of barrier and mechanical properties failed to describe the behaviour of the composites and appropriate discussion regarding this aspect was also carried out. From the results, CNW exhibit novel significant potential in coatings, membranes and food agrobased packaging applications.     

SYNERGISTIC EFFECT OF Cu-ZSM-5 ZEOLITE ON FLAME RETARDED PP BY MELAMINE SALT OF DIPENTAERYTHRIOL PHOSPHATE

A novel intumnescent flame melamine salt of dipentaerythriol phosphate (MDP),was prepared from dipentaerythritol (DPE) polyphosphoric acid,and melamine.The flammability,combustion behavior,and thermal degradation and stability of PP-MDP were characterized.When MDP loading was 20 wt%,LOI values of the composites reached up to 27%,and UL94 rating,V-2.PP-MDP containing 1 wt% Cu-ZSM-5 presented the highest LOI value of 30.5% and UL94 rating,V-0,and released lest heat during cone test.TG data showed that the ...     

聚氨酯/分子筛复合材料的制备及性能

以聚对苯二甲酸乙二醇酯（PEA）、甲苯二异氰酸酯（TDI-80）、扩链剂（MOCA）、分子筛为原料,采用预聚体法制备了聚氨酯／分子筛复合材料．考察了分子筛的种类及加入量对聚氨酯／分子筛复合材料的耐溶剂性能、力学性能及热分解温度的影响．结果表明：在相同加入量的前提下,采用4A和13X分子筛制备的复合材料,前者的耐溶剂性能及力学性能要优于后者,当加入量为5％时,性能达到最佳．两者的加入均能提高复合材料的热分解温度,但影响相差不大．     

Synthesis and properties of organo-fly ash/polyaniline with core/shell structure based on emulsion polymerization

Organo-fly ash(OFA) was prepared with pretreated fly ash(FA) and hexadecyltrimethyl ammonium bromide (HDTMAB),and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios(2.0 wt%,5.0 wt%,10.0 wt%,15.0 wt%and 20.0 wt%) in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier.A polymerization procedure was supposed.The electrical conductivities of the composites were tested by the four-probe technique.The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction,respectively.Morphologies of FA,OFA and the composites were observed by SEM.The element analysis was performed by energy dispersive spectrometry.The thermal stability of the composites was analyzed by TGA.The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA,and the lowest value was 0.62 S/cm.HDTMAB and PAn were just adsorbed on the surface of FA and OFA,respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA.The surface became smoother after organification of FA by using HDTMAB,and its content on FA surfaces was about 26.9 wt%.The core/shell structure of the composite was observed by SEM analysis.The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system,the heat stability of PAn was increased by decreasing 31.8 wt%of weight loss after introducing 20 wt%of OFA.     

The influence of CaCO3 filler component on thermal decomposition process of PP/LDPE/DAP ternary blend

Polypropylene‐low density polyethylene (PP‐LDPE) blends involving PP‐LDPE (90/10 wt%.) with (0.06 wt%) dialkyl peroxide (DAP) and different amounts (5, 10, 20 wt%) of calcium carbonate (CaCO₃) were prepared by melt‐blending with a single‐screw extruder. The effect of addition of CaCO₃ on thermal decomposition process and kinetic parameters, such as activation energy and pre‐exponential factor of PP‐LDPE blend with DAP matrix, was studied. The kinetics of the thermal degradation of composites was investigated by thermogravimetric analysis in dynamic nitrogen atmosphere at different heating rates. TG curves showed that the thermal decomposition of composites occurred in one weight‐loss stage. The apparent activation energies of thermal decomposition for composites, as determined by the Tang method (TM), the Kissinger–Akahira–Sunose method (KAS), the Flynn–Wall–Ozawa method (FWO), and the Coats–Redfern (CR) method were 156.6, 156.0, 159.8, and 167.7 kJ.mol^?1 for the thermal decomposition of composite with 5 wt% CaCO₃, 191.5, 190.8, 193.1, and 196.8 kJ.mol^?1 for the thermal decomposition of composite with 10 wt% CaCO₃, and 206.3, 206.1, 207.5, and 203.8 kJ mol^?1 for the thermal decomposition of composite with 20 wt% CaCO₃, respectively. The most likely decomposition process for weight‐loss stages of composites with CaCO₃ content 5 and 10 wt% was an A_n sigmoidal type. However, the most likely decomposition process for composite with CaCO₃ content 20 wt% was an R_n contracted geometry shape type in terms of the CR and master plots results. It was also found that the thermal stability, activation energy, and thermal decomposition process were changed with the increase in the CaCO₃ filler weight in composite structure. Copyright © 2009 John Wiley & Sons, Ltd.     

The effects of natural zeolite and silane coupling agents on melting and crystallization behaviour of polypropylene

The thermal characterization of polypropylene (PP) composites containing untreated and treated zeolite with different silane coupling agents was carried out using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) to investigate the effects of natural zeolite and surface modifiers on melting, crystallization and degradation behaviour of PP. 3-aminopropyltriethoxysilane (AMPTES), methyltriethoxysilane (MTES) and 3-mercaptopropyltrimethoxysilane (MPTMS) were used as surface modifiers at four different concentrations (0.5–2.0 mass%). Thermal analyses indicated that silane treatment and 2–6 mass% zeolite addition have no significant effect on the melting and degradation temperatures of the composites. The crystallization temperatures of the composites were increased due to the nucleating effect of the zeolite. The influence of the modifiers on the interactions between PP and zeolite was determined by the activities of untreated and treated zeolite. The maximum interactions leading to good adhesion were observed in the AMPTES treated composites. Also, non-isothermal crystallization kinetics of the composites was analyzed using Avrami and Kissinger models.     

A method for simultaneously improving the flame retardancy and toughness of PLA

In order to modify the brittleness and flame retardant properties of poly(lactic acid) (PLA), a series of flame retardant toughened PLA composites were prepared using poly(ethylene glycol) 6000 (PEG6000) as a toughening and charring agent together with ammonium polyphosphate (APP) as an acid source and blowing agent. The fire and thermal behavior of PLA/PEG/APP composites was evaluated by limiting oxygen index (LOI), UL‐94, cone calorimeter, and thermogravimetric analysis (TGA). The results showed that the PLA/PEG/APP system had good charring ability and could improve the flame retardancy of PLA. When the content of APP in the composites was more than 5 wt%, all samples could reach UL‐94 V‐0 rating. The results of mechanical property tests demonstrated that the brittleness of PLA was also improved after blended with PEG6000. All the PLA/PEG/APP composites with an APP content of less than 10 wt% showed an obvious neck and fracture behavior, that is, the tensile behavior of PLA was changed from brittle to ductile. Copyright © 2010 John Wiley & Sons, Ltd.     

Photocatalytic synthesis of urea from in situ generated ammonia and carbon dioxide

TiO(2) and Fe-titanate (different wt%) supported on zeolite were prepared by sol-gel and solid-state dispersion methods. The photocatalysts prepared were characterized by X-ray diffraction, scanning electron microscopy and ultraviolet (UV)-visible diffuse reflectance spectroscopy techniques. Photocatalytic reduction of nitrate in water and isopropanol/oxalic acid as hole scavengers are investigated in a batch reactor under UV illumination. The yield of urea increased notably when the catalysts were supported on zeolite. The Fe-titanate supported catalyst promotes the charge separation that contributes to an increase in selective formation of urea. The product formation is because of the high adsorption of in situ generated CO(2) and NH(3) over shape-selective property of the zeolite in the composite photocatalyst. The maximum yield of urea is found to be 18 ppm while 1% isopropanol containing solution over 10 wt% Fe-titanate/HZSM-5 photocatalyst was used.     

Preparation and properties characterization of gallic acid epoxy resin/succinic anhydride bionanocomposites modified by green reduced graphene oxide

Graphene oxide was reduced into reducing-graphene oxide (r-GO) successfully using gallic acid (GA) as a green reducing agent. Biobased gallic acid epoxy resin (GAER) was synthesized from renewable GA, and the biobased GAER/r-GO nanocomposites and glass fiber-reinforced composites were prepared with succinic anhydride as a curing agent. The dynamic mechanical, thermal, and mechanical properties of the composites with varying r-GO contents were characterized. When the content of r-GO was 0.5 wt%, the glass transition temperature was 10.4°C higher than the pure resin system. The thermal and mechanical properties were increased with increasing r-GO content; when the r-GO content was 1.0 wt%, the initial degradation temperature was enhanced by approximately 6.8°C, the tensile and impact strengths were 34.5% and 49.1% higher, respectively, than the pure cured GAER. The impact strength of GAER was higher than that of the bisphenol A epoxy resin/SUA curing system, but the tensile strength was lower than it.     

Flame retarded composite panels from sugar beet residues

Sugar beet residues and various additives were used to prepare panels by forming the semi-dry or wet mixtures and pressing the composites at a temperature of 150?°C and pressures of 100?C5410?kPa for up to 105?min. The highest panel density and second highest thickness were observed when a combination of calcium hydroxide and boric acid were used as additives using the semi-dry procedure. SEM images revealed that at pressures over 1000?kPa the cell wall structure of sugar beet was completely unrecognizable. The FTIR results indicated that the non-cellulosic polysaccharides contributed significantly to the properties of the panels by acting as adhesives. The best flame retardant parameters were also obtained with the calcium hydroxide/boric acid formulation. In comparison to composites prepared from recycled paper and mixtures of sugar beet shreds with recycled paper, higher density panels were prepared at lower pressure from sugar beet sources.     

热致液晶共聚酯与聚酯热塑弹性体复合物的制备与性能

原位缩聚法制备了一系列(对羟基苯甲酸-对苯二甲酸-间苯二酚)(HB-TA-RES)热致液晶共聚酯与聚对苯二甲酸丁二酯-聚四亚甲基醚热塑弹性体(PBT-PTMG)复合物,并用POM,TGA,WAXD,SEM及动态应力流变仪等手段进行了表征.复合物在较宽的共聚酯含量范围(30 wt%~70 wt%)或共聚酯组成不同时(共聚酯中HB含量20 mol%~80 mol%)均具有热致液晶行为.当复合物中共聚酯含量≤50 wt%以及共聚酯中对羟基苯甲酸(HB)含量≤60 mol%时,共聚酯分子的结构更加均匀化,结晶组分的结晶行为受到限制,基体与液晶组分具有较好的复合效果,不表现明显的相分离行为.复合物与相应的纯共聚酯相比,具有较好的热稳定性;其粘度均比基体PBT-PTMG小.当复合物中共聚酯含量≥30 wt%时,其粘度下降尤为显著,表明其具有较好的加工性.     

Thermal behavior of cardanol resin reinforced 20 mm long untreated bagasse fiber composites

Recently the attention in composite materials reinforced with natural fibers has significantly increased due to the new environmental legislation as well as consumer pressure that forced manufacturing industries to search substitutes for the conventional materials, e.g., glass fibers. In this way, the objective of the paper was to evaluate the thermal properties of sugarcane bagasse fiber-cardanol resin composites. Fibers were cut down to 20?mm length in diagonally. These fibers were mixed with the cardanol and epoxy resin, and fabricate in a biocomposites with different compositions, such as 0, 5, 10, 15, and 20?wt%. The thermal properties were evaluated by thermal gravimetric analysis and differential thermogravimetry analysis and also chemical formulation studied in Fourier transform infrared spectroscopy. The results showed the improved thermal strength of the composites in comparison to the neat polymer (0?wt%).     

Effect of preheat and encapsulation of steel particles on the interaction with Bisphenol A composites

In this study, the mechanical and thermal behavior of the steel particles (SP) fabricated epoxy-based composites were investigated. The purpose of using SP was to find out their suitability and compatibility to be used as low-cost fillers for epoxy-based composites. A special steel-cast metal mold was used to fabricate the composites via self-casting method. The effect of SP concentration (10, 20, 30 and 40 wt%) on various properties of the epoxy/SP composites was explored. Another sample was prepared using the optimum loading with a special treatment using heat and encapsulation of the SP. Mechanical properties of the composites were analyzed through tensile, flexural and impact testing. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to examine the structural and morphological properties. In addition, thermal properties of the composites were analyzed with the thermogravimetric analyzer (TGA). Results indicated that the addition of PS into epoxy improved both tensile and flexural strength up to 98.5% and 147.6%, respectively, compared to the neat epoxy (NE). The decomposition temperature was raised nearly 18 °C for adding 30 wt% SP which was the maximum among all other composites. Results showed that 30 wt% of SP was the optimum loading for the better properties of the composites. In addition, the preheat treatment of the particles and the encapsulation process established a better interaction between the epoxy and the particles which resulted in the superior performance of the composites compared to the other samples. Overall, the improved mechanical and thermal properties of the SP-fabricated epoxy composites indicate that the epoxy/SP composite is a good candidate for structural and high temperature applications.