Curing and combustion properties of a PU‐coating system with UV‐reactive phosphazene

A UV‐curable polyurethane (PU)‐coating system containing phosphorus is formulated by the combination of photoinitiator, PU acrylate oligomer, and UV‐reactive phosphazene monomer. PU acrylate oligomer is prepared by the addition of 2‐hydroxyethylmethacrylate (HEMA) to NCO‐terminated PU prepolymer. UV‐reactive phosphazene monomer is derived from the HEMA substitution reaction to hexachlorocyclotriphosphazene (NPCl₂)₃. The curing reaction of this PU‐coating system is carried out by UV irradiation. The resultant UV‐cured PU‐coated films demonstrated better performance properties than those of original UV‐cured PU acrylate (UV‐PU) without UV‐reactive phosphazene monomer. Furthermore, their thermal properties are investigated by a thermogravimetric analyzer and a dynamic mechanical thermal analyzer, respectively. The combustion behaviors of these UV‐cured PU‐coated films are evaluated by the measurements of a limiting oxygen index and a cone calorimeter. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1980–1991, 2002     

Thermal stability,surface wettability and mechanical behavior of highly ordered ZnO-doped thermoplastic polyurethane films with hierarchically porous structures

In this paper, the effect of ZnO nanoparticle on thermal, microstructure, mechanical behavior, superhydrophobicity of thermoplastic polyurethane (TPU), ZnO/TPU composite materials with doped-ZnO nanoparticles were obtained via a solution blending method. The results show that the melting temperature region in soft segments of ZnO/TPU composite materials was the transition temperature region. The added ZnO slightly enhances the crystalline slipped of ZnO/TPU composite materials, and effectively hinder the transfer of high temperature small gas molecules. Due to the added ZnO nanoparticles, the microphase separation and ordered structures in TPU are reduced. In TPU, and between TPU and ZnO nanoparticles, there are variations in electron density at hard phase and soft phase interfaces. The good ZnO/TPU composites exhibit high water repellence with water contact angle of ~157°. The prepared ZnO/TPU nanocomposites show mechanical properties that are superior to those of pristine TPU. Tensile strength and storage modulus increase by 47.1% and 39.8% at ZnO loading values of 10 wt%. The results indicate that thermal behavior, microstructure, superhydrophobicity and the mechanical behavior of TPU composite materials can be enhanced by the doped ZnO.     

Alumina reinforced eucryptite ceramics: Very low thermal expansion material with improved mechanical properties

Composite materials formed by a LAS matrix reinforced with second phases are promising materials in many applications where better mechanical properties than those corresponding to conventional low thermal expansion coefficient materials are required. In this study we will show the capability of the design of a LAS-alumina submicron composite. The main scope of this work is to test the sinterability of the composites and to design a composition for a very low thermal expansion submicron composite. For this purpose, Taimei alumina (TM-DAR) powders and an ad hoc synthesized β-eucryptite phase were used to fabricate the composite. XRD phase compositions and microstructures are discussed together with data from dilatometries in a wide temperature range. The results obtained show the possibility of designing a submicron composite with a very low thermal expansion coefficient and improved mechanical properties that can be used in oxidizing conditions.     

沉淀均聚氯醇橡胶的合成及研究

应用沉淀聚合方法在无水无氧气环境下合成均聚氯醇橡胶.通过相同硫化配方处理来自武汉及日本某工厂和本实验室沉淀聚合法自制合成的均聚氯醇橡胶生胶,并用高温硫化制备各均聚氯醇橡胶复合材料;对其力学性能、分子量和热稳定性进行了分析表征,对自制的均聚氯醇橡胶做了红外表征.实验结果表明:本实验室沉淀聚合自制合成的均聚氯醇橡胶红外表征表明符合均聚氯醇橡胶的结构,力学性能强于武汉某工厂接近日本某工厂,分子量大于日本某工厂,热稳定性强于武汉及日本某工厂.     

Flame retardation improvement of aqueous‐based polyurethane with aziridinyl phosphazene curing system

Aziridinyl phosphazene (NPAZ) was introduced to aqueous‐based polyurethane (PU) as a flame retardant and a postcuring agent, mainly because of the presence of phosphorus compositions, as well as the reactive aziridinyl groups on NPAZ. This dual‐function NPAZ was prepared from the substitution reaction of hexachlorocyclotriphosphazene with aziridine. Aqueous‐based PU was treated with NPAZ and its curing reaction took place upon drying. The performance properties of this NPAZ cured PU (NPAZ‐PU) were improved and better than those of the original PU. The phosphorus composition from NPAZ was evenly distributed on this NPAZ‐PU film, which was identified by the phosphorus mapping on the energy dispersion spectrum. The physical and mechanical properties of NPAZ‐PU were evaluated by the measurements of the gel content, water uptake, ethanol swelling, and tensile stress. The thermal properties of NPAZ‐PU were investigated by thermogravimetric analysis (TGA), TG analyzer‐interfaced FTIR, and dynamic mechanical thermal analysis. Furthermore, its combustion behaviors were demonstrated with the data of a cone calorimeter measurement. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 662–673, 2001     

Recycling of textile waste into green composites: Performance characterization

Recycling of any waste is as such a worldwide phenomenon. In this context application of textile waste for development of some value added product has been thought of in this work. Textile fabric waste is collected from various sources. These waste materials are garneted, so as to produce loose fibrous material. Subsequently this fibrous material was converted into nonwoven web and also twisted strand for manufacturing of 3D woven preforms to be used in composites. In case of nonwoven preforms, the webs are produced by combining polypropylene with cotton component with different proportions. Composites of various specifications are developed to examine their application in several end uses. These composite materials are characterized for their mechanical and thermal behavior in order to find out the response against tensile loading, impact force and thermal loading. The effects of moisture absorption on mechanical properties of these composites are investigated. As the percentage of PP fibres is increased in the web, mechanical performance of the composite material is improved in general. The exposure of composite material to high humidity condition has not shown any significant change in their mechanical behavior. 3D woven fabric reinforced composite produced by using garneted fibre yarn and virgin cotton OE yarn didn't exhibit any significant difference in the mechanical and thermal behavior of composite. The results confirmed that textile waste material can be safely used as reinforcing structure in composite manufacturing. POLYM. COMPOS., 35:1960–1967, 2014. © 2014 Society of Plastics Engineers     

EPS颗粒对超轻水泥基复合保温材料性能的影响

聚苯乙烯泡沫塑料颗粒(EPS颗粒)作为水泥基复合保温材料的超轻骨料,对水泥基复合保温材料力学性能、热工性能影响显著。以水泥为胶凝材料,EPS颗粒、混合材、泡沫剂和改性剂、水等为主要原料,采用物理发泡工艺制备干表观密度不大于120 kg/m³的超轻水泥基复合保温材料(UCIM)。通过设计不同体积掺量的EPS颗粒,分析EPS颗粒掺量对泡沫混凝土基体孔结构、超轻水泥基复合保温材料强度和热工性能的影响规律。结果表明,适宜掺量EPS颗粒可显著提高超轻水泥基复合保温材料抗压强度和抗拉强度,并确保超轻水泥基复合保温材料具有良好的热工性能,即通过EPS颗粒与泡沫混凝土基体的协同作用,协调力学性能和热工性能,制备出高性能超轻水泥基复合保温材料。     

Thermal and mechanical properties of dough modeling compound reinforced ethylene propylene diene monomer/silicon rubber composites

Ethylene propylene diene monomer (EPDM)/silicon rubber composite was prepared by adding dough‐modeling compound (DMC). EPDM/silicon rubber is the matrix of the composite, and DMC is a disperse phase (reinforced phase). The morphology of the composite was studied by scanning electron microscopy, and it was found that the compatibility of DMC/EPDM/silicon rubber composite was good. The influence of the DMC and peroxide curing agents on the mechanical and thermal properties were studied. The results showed that the mechanical and thermal properties of the composite were best, when DMC/EPDM/silicon rubber was 80/25/75. The thermal properties of the composite prepared with added equivalent dicumyl peroxide was better than those with added benzoperoxide, but Shore A hardness and elongation at break are unchangeable. The integral properties of DMC reinforced EPDM/silicon rubber composite was much better than three raw materials. POLYM. COMPOS. 27:621–626, 2006. © 2006 Society of Plastics Engineers     

Al_2O_3–ZrO_2复相陶瓷的低温力学性能和热学性能

采用无压烧结法制备Al2O3–15%（质量分数）ZrO2（简称ZTA）复相陶瓷,研究了ZTA复相陶瓷在293～77K的力学性能以及300～5K的热学性能,分析了ZTA复相陶瓷在不同温度断裂时断面上ZrO2发生的相变量和相变区宽度。结果表明：ZTA复相陶瓷的抗弯强度、断裂韧性和Vickers硬度均随温度下降而逐渐提高;77K时抗弯强度、断裂韧性和Vickers硬度比293K时分别提高了10.8%、19.7%和10.4%;ZTA复相陶瓷的热导率随温度下降先增大,在97K时达到最大值,然后随温度下降而降低。低温环境增强了ZTA复相陶瓷中应力诱导t-ZrO2→m-ZrO2的相变增韧效应,提高了ZTA复相陶瓷的低温力学性能。ZTA复相陶瓷具有良好的低温力学性能和较小的低温热导率,是一种有广阔应用前景的低温结构陶瓷材料。     

氧化石墨烯改性磺酸型水性聚氨酯的制备与性能研究

首先对石墨进行氧化处理制备氧化石墨(GO),然后对GO进行超声处理得到氧化石墨烯(GOs),并通过共混法制备了水性聚氨酯(WPU)/GOs复合材料。讨论了超声分散以及GOs加入量对WPU/GOs复合材料力学性能和热稳定性的影响。结果表明,经过超声分散的复合材料的力学性能比未超声分散的好;随着GOs含量的增加,复合材料的拉伸强度先增大后减小,断裂伸长率逐渐减小;加入质量分数0.50%的GOs,其WPU/GOs复合材料的热分解温度可提高44.7℃,明显提高WPU的热稳定性。     

Synthesis and properties of electromagnetic wave shielding polymer materials with low flammability

Novel polyethylene‐ and polypropylene‐based electromagnetic wave shielding and absorbing composite materials with low combustibility, enhanced thermal and mechanical properties, containing graphite, grinded wood, and fire retardants, were developed and investigated. Flame‐resistance, thermal and mechanical properties of these materials was investigated. Electromagnetic wave reflection coefficients over the frequency range 20–40 GHz were measured; at moderate concentration (10–15%) of functional filler, reflection coefficient can be as low as ?16 dB for PE and ?11 dB for PP composite, respectively. Coke formation mechanism was investigated, the principal role in this process is attributed to aromatization and condensation of aromatic compounds with the formation of polycyclic aromatic systems, an important role of phosphoric acids in accelerating this process was found. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

TEM,XPS and thermo-mechanical properties of novel sustainable hybrid coatings

This work contributes to the development of a new generation of protective coatings composed of organic–inorganic materials. A silica based hybrid film was used in this work as high performance materials. The silica sol–gel film reveals enhanced thermo-mechanical properties in comparison with the pure polymer film. Herein, we demonstrate the possibility of employing cheap SiO₂ as prospective nano-fillers for hybrid coatings with active thermo-mechanical properties. Organic–inorganic hybrid coatings based on polyimide and silica were synthesized through a simple physical mixing technique. 3,3′,4,4′-Biphenyltetracarboxylic dianhydride (BPDA), benzene-1,3-diamine (BDA), 3,3′-oxydianiline (ODA) and SiO₂, were used as precursors for the hybrid coatings. These hybrid coatings were deposited via spin coating onto a galvanized iron, aluminum and copper in order to study the adhesive strength. The effects induced by the silica content on the mechanical properties of the coated samples were investigated. The mechanical properties of hybrid composite were found to be enhanced compared to polyimide coating. The main objective was to observe potential improvements in the mechanical and thermal properties of PI–silica hybrid films. Morphology, and structural changes in the composite films were studied as well as adhesion and impact strength and these characteristics were compared with those of unreinforced polyimide films.     

Effect of surface treatment on the physicomechanical and thermal properties of high‐density polyethylene/olive husk flour composites

In this study, a particular interest was focused on the recovery of lignocellulosic waste of olive husk flour (OHF) by its incorporation as filler in manufacturing composite materials based on high‐density polyethylene (HDPE) matrix with various filler contents (10, 20, and 30 wt %). The problem of incompatibility between the hydrophilic filler and the hydrophobic matrix was treated with two methods: the first method consists of using maleic anhydride‐grafted polyethylene (MAPE) as compatibilizer in HDPE/OHF composites. The second method, was focused on the chemical modification of OHF by vinyl‐triacetoxy‐silane (VTAS). Fourier transform infrared spectroscopy is used to analyze both grafting and silanization reactions involved. Scanning electron microscopy was used to show the morphology of the flour surface. Furthermore, the physicomechanical and thermal characteristics of the various composite samples were investigated as a function of filler contents and treatment types. The results showed that the properties of the composite materials are positively affected by the silanization treatment of OHF and also by MAPE addition. However, better mechanical and thermal properties with less moisture absorption were obtained for the composite materials compatibilized with MAPE. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of TiO2-Modification on the Mechanical and Thermal Properties of Sugarcane Bagasse–EVA Composites

The effect of nano-particles of TiO₂ on the mechanical and thermal properties of sugarcane bagasse (SCB)–ethylene co-vinyl acetate (EVA) composite was investigated. Composite materials were prepared using a melt-mix intercalation method on a rheomex mixer coupled with a single screw extruder. differential scanning calorimeter (DSC), thermogravimetric (TG) analyser and an Instron, were used to probe the thermal and mechanical properties of the samples. Composites with TiO₂ were compared with those without TiO₂ but with the same content of sugarcane bagasse (SCB). After the addition of TiO₂, the tensile strength increased by 10%, from 11.26 MPa for neat EVA, which correlated with the enthalpy of fusion, however, the tensile strength decreased by 18% at higher SCB loading. Elongation at break decreased from 463 to 0% as the filler (SCB) was increased which was inversely proportional to the modulus. The composite showed an improved thermal stability with the addition of TiO₂.     

Curing reaction mechanism and heat resistance properties of hexa‐(4‐carboxyl‐phenoxy)‐cyclotriphosphazene/bisphenol A aniline benzoxazine blends

A blend system of hexa‐(4‐carboxyl‐phenoxy)‐cyclotriphosphazene (HCPCP) and bisphenol A aniline benzoxazine (BA‐a) was prepared, and its curing reaction mechanism and heat resistance properties were studied. The curing reaction mechanism of the blend was explored by differential scanning calorimetry, Fourier transform infrared spectroscopy, and modeling software using model compounds Ar‐COOH and hexachlorocyclotriphosphazene (HCCP). The heat resistance properties of the cured blends were studied by thermogravimetric analysis and dynamic mechanical analysis. The polymerization of benzoxazine was catalyzed by HCPCP through phosphazene ring and acid groups, and phosphazene played a predominant role. Compared with the materials with a single functional group (Ar‐COOH and HCCP), HCPCP containing two functional groups (phosphazene ring and acid) exhibited weaker catalytic effects, mainly due to the high molecular weight of HCPCP obstructing movement and causing steric hindrance. In addition, HCPCP had a positive effect on the thermal stability of polybenzoxazine from 250 to 400 °C. When the HCPCP content reached 3%, the cured blend had the highest glass‐transition temperature (222.2 °C), which is higher by 20 °C than that of cured benzoxazine. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46389.     

Dynamic viscoelastic properties and thermal properties of Ni powder–epoxy resin composites

The composite materials containing metal Ni powder of 5–15 μm in size were prepared by use of the matrix epoxy resin of glycidyl amine crosslinked with bis-4-amino-3-methylcyclohexyl methane and 2,4-diamine 3,5-dimethyltoluene. Dynamic viscoelastic properties of the composites at various volume fraction (Φ_p) of Ni powder have been measured over the temperature range from 30 to 300°C. The peak temperatures in dynamic loss modulus–temperature diagrams of the composite increased with increasing Φ_p, although the peak position was abruptly shifted to lower temperatures in the range of Φ_p more than 0.245. At this high concentration of Φ_p, agglomeration of the particles occurring in the composite lead to reduction of the interaction between Ni particle and epoxy resin. Parallel studies on the thermal conductivity (λ) of the composites materials showed that the value of λ at Φ_p = 0.245 increased by approximately 7 times that of the original epoxy resin. The shape of Ni particles also affected the thermal durabilities of the composites; the rough surface of Ni powder yields a higher storage modulus of the composite than that of the materials containing the powder with a smooth surface, which had been brought through a ball-milling process. The finding suggested that the increasing in specific surface area of the powder improved the thermal durability of the composites as well as their mechanical properties. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2593–2598, 1998     

Effect of thermal treatment on the tensile and in‐plane shear behavior of carbon fiber‐reinforced poly(phenylene sulfide) composite specimens

The effect of PPS matrix evolution occurring during thermal treatment of carbon fiber‐reinforced PPS plies prior to their consolidation to laminates on the mechanical behavior of the composite material has been investigated. The thermal treatments were performed at temperatures and times, which are relevant for processing PPS composites. All thermal treatments were carried out in an oven in air to facilitate the presence of oxygen, while the subsequent consolidation was performed in an autoclave. The tensile and in‐plane shear behavior of both, thermal‐treated and untreated materials, was investigated. Differential scanning calorimetry and microscopy analyses were made to evaluate the effect of the performed thermal treatments on degree of crystallinity and porosity of the laminates. The mechanical tests carried out have shown an appreciable degradation of the mechanical properties investigated. The observed degradation increases with increasing thermal treatment temperature and time when thermal treatments were carried out on each single composite ply prior to the consolidation. On the other hand, when, prior to the consolidation, the whole set of plies was subjected to thermal treatment, improved mechanical properties were observed. The results were discussed under the viewpoint of PPS matrix evolution during processing of the composite plies in the presence of oxygen. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

One‐Pot Substitution Approach for the Syntheses of Nonfunctional and Functional Poly[(amino acid ester)phosphazene] Biomaterials

Biodegradable polyphosphazenes are important class of biomaterials. Their preparation typically requires specialized setup, inert conditions, and cumbersome and multiple processes. This work focuses on the synthesis of both nonfunctional and novel functional poly[(amino acid ester)phosphazene]s using a simplified thermal ring opening polymerization in air, followed by one‐pot ( 1P ) room temperature substitution, also in air. While some hydrolysis was inevitable under such conditions, purified materials with lower polydispersity indices than previously reported and acceptable yields were successfully and reproducibly obtained. The poly[(amino acid ester)phosphazene]s developed in this work are based on l ‐alanine, l ‐phenylalanine, and l ‐methionine with l ‐glutamic acid to render them functionality. Characterization of these synthesized materials demonstrated that the 1P substitution was successful in developing mono‐ and co‐substituted poly[(amino acid ester)phosphazene]s. Cytotoxicity studies on 2D films showed the materials to be compatible with NIH‐3T3 fibroblasts while confocal imaging of cells showed a well‐spread morphology with abundant F‐actin within the cytoskeleton. The l ‐phenylalanine‐based poly[(amino acid ester)phosphazene]s also showed significantly enhanced cell viability over tissue culture polystyrene at days 1 and 3 of cultivation (p < 0.01). Overall, this study has shown that poly[(amino acid ester)phosphazene]s can be obtained with acceptable yields and straightforward reaction conditions, leading to materials suitable for broader biomedical applications.

     

Graft copolymerization of ϵ-Caprolactam onto Kevlar-49 fiber surface and properties of grafted Kevlar fiber reinforced composite

The anionic graft copolymerization of ϵ-caprolactam onto a Kevlar-49 fiber surface was carried out by using a metalation reaction in a dimethyl sulfoxide solution of sodium hydride. The effects of reaction conditions on the graft yield and on the tensile strength of the fiber have been investigated. Graft yield significantly increased with increasing metalation time, NaH concentration, and monomer concentration. The graft yield varied from 6 to 32% with reaction conditions. The tensile strength of the fiber depended predominantly on NaH concentration. The retained tensile strength was over 93% when the concentration of NaH was below 2.1 mmol/L per 0.5 g of Kevlar. The discontinuous Kevlar fiber reinforced composites were prepared by a blending/melt-pressing method. In thermomechanical and dynamic mechanical analyses, the relaxation peak of grafted Kevlar fiber/Nylon 6 composite film moved to higher temperatures, compared with the original Kevlar fiber/Nylon 6 composite film. The grafted Kevlar fiber reinforced Nylon 6 composite film exhibited mechanical properties superior to those of the original Kevlar fiber reinforced composite film. The higher thermal and mechanical properties were due to the effect of higher interfacial interaction between the grafted Kevlar fiber and matrix. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 99–107, 1997     

Bamboo fiber polypropylene composites: Effect of fiber treatment and nano clay on mechanical and thermal properties

In the current study, bamboo fibers were modified with sodium meta‐periodate in order to improve the mechanical and thermal properties of the bamboo‐clay‐polypropylene (PP) composites. Both raw and treated bamboo fibers were used in the manufacturing of the composites. The mechanical and thermal properties of the composites from modified bamboo fibers were found to increase considerably compared with those of untreated fibers. Tensile strengths of (raw bamboo fiber)/PP, (raw bamboo fiber‐clay)/PP, and (treated bamboo fiber‐clay)/PP composites showed a decreasing trend with increasing fiber loadings. However, the values for the chemically modified (bamboo fiber)‐clay‐PP composite at all mixing ratios were found to be higher than that of the original PP. The scanning electron micrographs showed that interfacial bonding between the treated fiber‐clay and matrix has significantly improved. It was determined that better dispersion of the filler into matrix occurred on 5% clay addition and fiber treatment. J. VINYL ADDIT. TECHNOL., 21:253–258, 2015. © 2014 Society of Plastics Engineers