Cured melamine systems as thick fire-retardant layers deposited by combination of plasma technology and dip-coating

Melamine and melamine resins are widely used as fire-retardants for polymer building materials. Cured melamine systems are used in heat-sensitive items, such as furniture and window frames and sills. In this work, differently cured methylated poly(melamine-co-formaldehyde) (cmPMF) resins were used as fire-retardant coverage for poly(styrene) (PS) and poly(ethylene) (PE) building materials. Such polymer layers should have several tenths of micrometers thickness to produce sufficient fire retardancy. These thick layers were produced by dip-coating. To promote sufficient adhesion of such thick coating to the polyolefin substrates, also in the case of high temperatures occurring at fire exposure, the polymer substrates were firstly coated with a few hundred nanometer thick adhesion-promoting plasma polymer layer. Such thin plasma polymer layers were deposited by low-pressure plasma polymerization of allyl alcohol (ppAAl). It was assumed that the hydroxyl groups of ppAAl interact with the melamine resin; therefore, ppAAl was well suited as adhesion promoter for thick melamine resin coatings. Chemical structure and composition of polymer films were investigated using infrared-attenuated total reflectance and X-ray photoelectron spectroscopy (XPS). Peel strengths of coatings were measured. After peeling, the peeled polymer surfaces were also investigated using optical microscopy and XPS the layers for identification of the locus of peel front propagation. Thermal properties were analyzed using TGA (thermo-gravimetric analyses). Finally, the fire-retardant properties of such thick coated polymers were evaluated by exposure to flames.     

Plasma deposition of adhesion-promoting polymer layers onto polypropylene for subsequent covering with thick fire retardant coatings

Melamine resins were used as 50-μm-thick fire retardant coatings for polypropylene (PP). Preceding deposition, low-pressure plasma polymer films of allyl alcohol were coated onto PP to improve the adhesion between PP and melamine resin coatings. The efficiency of such fire retardant coatings was confirmed by flame tests. The plasma-deposited polymer and the dip-coated melamine resin films were characterized by Fourier transform infrared-attenuated total reflectance spectroscopy and X-ray photoelectron spectroscopy (XPS). The adhesion of coatings was measured using a 90° peel test with a doubled-faced adhesive tape. To detect the locus of failure, the peeled layer surfaces were inspected using optical microscopy and XPS. Thermal properties of PP thick melamine resin-coated films were analyzed by thermogravimetric analysis.     

Surface modification of films of various high temperature resistant thermoplastics

The influence of different surface treatments on the physical and chemical surface properties of poly(etheretherketone) (PEEK), poly(phenylenesulfide) (PPS) and a liquid crystal polymer (LCP) was studied. For all the three polymers, the adhesion strength of an adhesively-bonded copper foil could be increased significantly by a chemical etching process using chromic sulphuric acid or a low pressure air-plasma treatment. However, for LCP the enhancement of adhesion by the surface treatments was lower than for the other polymers. Peel tests were employed for determining the adhesion strength of the copper foil. The physical surface properties were investigated by laser scanning microscopy (LSM). Contact-angle measurements and X-ray photoelectron spectroscopy (XPS) provided detailed information on the chemical surface properties. The detailed XPS analyses revealed different chemical mechanisms of the surface treatments depending on the polymer investigated. In all cases an incorporation of oxygen containing groups by the surface treatments was found to be responsible for a better adhesion of the copper foil on the treated polymer films compared to the untreated.     

水性含磷聚合物在涂料中的应用研究进展

水性含磷聚合物具有良好的热稳定性、耐腐蚀性等优点,是一种重要的环境友好型材料。本文主要介绍了水性含磷丙烯酸类和聚氨酯类等重要的水性含磷聚合物,并对这两种聚合物的合成及其在水性防火涂料和防腐涂料中的应用进行了讨论。分析结果表明：以水性含磷聚合物为基料的防火涂料热稳定性较好,成炭率明显增加,阻燃性能大大提高;以水性含磷聚合物为基料的防腐涂料,漆膜附着力增强,防腐性能提高。提出今后的研究方向是：①将磷与卤素、氮、硅等元素同时引入水性聚合物中,以协同阻燃;②将含磷基团引入聚合物分子内,作为基料来提高阻燃性能。     

A comparison of gas-phase methods of modifying polymer surfaces

Oxidation is the most common surface modification of polymers. This paper presents a comparison of five gas-phase surface oxidation processes: corona discharge, flame, remote air plasma, ozone, and combined UV/ozone treatments. Well-characterized biaxially oriented films of polypropylene and poly(ethylene terephthalate) were treated by each of the five techniques. The surface-treated films were then analyzed by X-ray photoelectron spectroscopy (XPS or ESCA), contact-angle measurements, and Fourier-transform IR (FTIR) spectroscopy. Corona, flame, and remote-plasma processes rapidly oxidize polymer surfaces, attaining XPS O/C atomic ratios on polypropylene of greater than 0.10 in less than 0.5 s. In contrast, the various UV/ozone treatments require orders of magnitude greater exposure time to reach the same levels of surface oxidation. While corona treatment and flame treatment are well known as efficient means of oxidizing polymer surfaces, the ability of plasma treatments to rapidly oxidize polymers is not as widely appreciated. Of the treatments studied, flame treatment appears to be the 'shallowest'; that is, the oxygen incorporated by the treatment is most concentrated near the outer surface of the film. Corona and plasma treatments appear to penetrate somewhat deeper into the polymers. At the other extreme, the UV/ozone treatments reach farther into the bulk of the polymers.     

高分子体系阻燃剂的研究新进展

使用阻燃剂可避免火灾中聚合物燃烧所带来的危害,但常用的阻燃剂存在阻燃效率低、燃烧时烟雾大或对复合材料的力学性能产生不良影响等缺点。本文介绍了新技术(包括纳米技术、微胶囊化技术)在高分子阻燃体系中的应用及研究现状,并对其阻燃机理进行了阐述。通过分析阻燃剂的发展趋向预测了阻燃高分子材料发展的一些新趋向。     

The study and application of LL flame retardant

Inorganic flame retardants containing water are less likely to produce toxic gases and smoke during combustion. The raw materials used to synthesize inorganic flame retardants are inexpensive and readily available. Therefore it is appropriate to research and synthesize these kinds of flame retardants and use them to produce building materials that have improved flame retardance and a low price and that constitute no environmental hazards. This paper introduces one kind of liquid,‘LL flame retardant’, which is the product of the reaction of phosphoric acid and aluminium hydroxide under specified reaction conditions. This flame retardant can be used for fire-retardant coating and can also treat the combustible materials, such as fabrics, paper and wood. This paper describes the preparations, properties and the mechanism of flame-retardant action of this additive.     

环境友好聚苯乙烯阻燃技术新进展

介绍了近年来环境友好阻燃聚苯乙烯(PS)的研究进展,分别从反应型阻燃剂和添加型阻燃剂展开阐述。反应型阻燃剂相对于添加型阻燃剂能为PS提供更高的阻燃效率和力学性能,并提出无卤、高效、低烟、低毒、多功能的新型PS阻燃材料的研究开发将是当今的发展方向。     

Characterisation of flame retardant plasma polymer deposited BOPP film

Abstract

Flame retardancy of polypropylene films was studied by plasma polymerisation technique. The surface of BOPP film was modified by boron containing plasma polymers at different plasma conditions. Plasma polymer coated polypropylene films were examined by flame retardancy test (limiting oxygen index, LOI) and TGA. Boron containing plasma polymer deposition on the film surface showed an improvement of flame retardancy. Furthermore, TGA thermograms pointed out that the first degradation temperature of treated polypropylene film was increased from 331 to 396°C, and the second degradation temperature was shifted from 401 to 455°C. Also, the plasma polymers were characterised by FTIR spectroscopy and XPS. According to XPS results, the BOPP surfaces treated with TMB showed significant difference in the composition with respect to the untreated sample. The FTIR spectra of plasma polymers obtained indicated that when the treatment time was increased to 60 min with a constant discharge power at 80 W, the absorption intensities of all the functional groups increased. As a result, boron containing plasma polymer treatment was found to be an effective method in enhancing the flame retardancy of BOPP film.     

Improved adhesion of aluminum layers deposited on plasma and thermally treated poly(paraphenylene-vinylene) films substrates

Searching for better adhesion properties of metallic thin films to polymer substrates, we have studied the influence of the plasma and thermal treatments of poly(paraphenylene-vinylene) thin films on their adhesion to aluminum layers. The adhesion was found to be substantially increased when the polymer surface was treated with oxygen by RF sputtering, or when it was kept at high temperature prior to the metal deposition. An attempt has been made to explain the adhesion improvement in terms of surface analysis (XPS) and scanning electron microscopy (SEM) results of the treated surfaces. Both the metal-oxygen-carbon complex formation at the interface and the roughness induced by the oxygen treatment were found to be the reasons for the improved adhesion properties.     

Adhesion of calcium phosphate coatings on polyethylene (PE), polystyrene (PS), poly(tetrafluoroethylene) (PTFE), poly(dimethylsiloxane) (PDMS) and poly-L-lactic acid (PLLA)

Calcium phosphate (CaP) coatings can be applied to improve the biological performance of polymeric medical implants. For clinical applications, a strong adhesion of the coating to the polymeric substrate is important. Therefore, the adhesion of rf magnetron-sputter-deposited CaP coatings on five polymers was studied: polyethylene (PE), polystyrene (PS), poly(tetrafluoroethylene) (PTFE), poly-L-lactic acid (PLLA) and poly(dimethylsiloxane) (PDMS). To influence the adhesion, the interface was varied in six different ways, e. g. by a plasma or ion-beam pretreatment, or by using a Ti interlayer. The adhesion was determined by using scratch, tensile and 180^° bend tests. Especially the polymers PE and PS needed a bombardment by energetic particles prior to or during coating deposition, to enable the formation of chemical bonds between the coating and the polymer, which gave adhesion. On PLLA and PDMS, being oxygen containing polymers, it was easier to establish a strong interface. An overtreatment of the polymeric substrates gave worse adhesion, probably due to the formation of weak low molecular weight (LMW) layers on the polymer. On PTFE, the use of a Ti interlayer was necessary to prevent the PTFE from UV degradation during coating deposition, as this caused cohesive failure within the PTFE. The results showed that each polymer requires a different approach for obtaining optimal adhesion. The observed adhesion could often be explained in the terms of processes occurred during the pretreatment of the polymers or the deposition of the coating.     

Influence of polymeric flame retardants based on phosphorus‐containing polyesters on morphology and material characteristics of poly(butylene terephthalate)

Flame retarded poly(butylene terephthalate) (PBT) is required for electronic applications and is mostly achieved by low molar mass additives so far. Three phosphorus‐containing polyesters are suggested as halogen‐free and polymeric flame retardants for PBT. Flame retardancy was achieved according to cone calorimeter experiments showing that the peak heat release rate and total heat evolved were reduced because of flame inhibition and condensed‐phase activity. The presented polymers containing derivatives of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide form immiscible blend systems with PBT. Shear‐rheology shows an increase in storage moduli at low frequencies. This is proposed as quantitative measure for the degree of phase interaction. The phase structure of the blends depends on the chemical structure of the phosphorus polyester and was quite different, depending also on the viscosity ratio between matrix and second phase. A lower viscosity ratio leads to two types of phases with spherical and additionally continuous droplets. Addition of the flame retardants showed no influence on the dielectric properties but on the mechanical behavior. The polymeric flame retardants significantly diminish the impact strength because of several reasons: (1) high brittleness of the phosphorus polyesters themselves, (2) thermodynamic immiscibility, and (3) weak phase adhesion. By adding a copolymer consisting of the two base polymers to the blend, an improvement of impact strength was obtained. The copolymer particularly acts as compatibilizer between the phases and therefore leads to a smaller phase size and to a stronger phase adhesion due to the formation of fibrils. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Characterization of antireflective coatings on poly(methyl methacrylate) substrate by different process parameters

The high/low refractive index organic/inorganic antireflective (AR) hybrid polymers were formed using the sol–gel process, in which TiO₂/2‐hydroxyethyl methacrylate (2‐HEMA) (high refractive index hybrid polymer) and SiO₂/2‐HEMA (low refractive index hybrid polymer) two‐layer thin films were formed on a hard coating deposited poly(methyl methacrylate) (HC‐PMMA) substrate by both spin coating and dip coating. The relationship between the process parameters and the optical properties, thickness, porosity, surface morphology, and adhesion was determined. The results show that the reflectance of the two‐layer thin films on HC‐PMMA substrate is less than 0.21% (λ = 550 nm), with good adhesion (5B) and a hardness of up to 4H. In addition, the thickness, porosity, and roughness of the films affect refractive index and the antireflection properties of the AR two‐layered thin film. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Advancements in traditional and nanosized flame retardants for polymers—A review

Synthetic polymers are ubiquitous materials widely used in construction, automotive, electronics, and countless commercial products. With the growing trend of polymer applications in everyday life, upholding the rigorous fire safety regulations has become a matter of concern. In this regard, numerous studies have been conducted for improving the fire retardancy of polymers, mainly through incorporating a diverse group of fire-retardant compounds into polymer-based composites. This review article aims to present a comprehensive overview of recent advances in the fire-retardant categories for polymeric materials especially emphasizing the nanosized fire retardants. Along with an attempt to focus attention on the consumption of conventional and possibly harmful fire retardants, potential eco-friendly alternatives are represented. A detailed discussion on the flame retardation mechanisms and conventional fire characterization techniques are also discussed.     

新型无机磷基阻燃剂的研究进展

以黑磷基阻燃剂为代表的纳米级新型无机磷基阻燃剂,在极低的添加量下即可实现高分子材料的阻燃性能和机械性能的同步提高,表现出良好的应用前景。综述了新型无机磷基阻燃剂的研究进展,重点介绍了黑磷基阻燃剂的功能化策略、制备工艺、阻燃机理和应用进展,最后对发展趋势进行了展望。总结并评述了黑磷制备所用的超声剥离、球磨剥离、电化学插层剥离等纳米化工艺和利用阻燃有机/无机物质对黑磷进行共价或非共价的修饰策略,对比分析了溶液共混、熔融共混、原位聚合、涂层等复合制备工艺的利弊,归纳了黑磷基阻燃剂的结构与性能之间的基本规律,提出了今后在科学创新和工程突破两方面的研究重点。     

A study of paint adhesion to polymeric substrates

In order to explore the fundamental mechanism of paint adhesion to polymer substrates the surface of polypropylene- ethylene propylene rubber (PP-EPR) blends was modified by flame or plasma treatments. The changes in surface composition and properties were investigated and discussed in light of the results of simple adhesion tests. The topography and surface properties of the PP-EPR samples were studied by employing various surface sensitive techniques. Additionally, the surface properties of the pre-treated PP-EPR were compared with the model polymers poly(methyl methacrylate) (PMMA) and polycarbonate (PC) displaying a poor and an excellent paint adhesion, respectively. Differential scanning calorimetry (DSC) measurements showed that the miscibility of the polymer substrate with paint components was an essential factor for the understanding of the adhesion mechanism. A general model of paint adhesion to polymer surfaces is proposed, where the degree of interdiffusion of the polymer chains of the substrate and paint in the interphase determines the adhesion strength.     

Action of phosphorus compounds on fire-retardancy of cellulosic materials: A review

Owing to their low cost phosphorus fire-retardants find vast application in making fire-retardant cellulosic compostions. They have been used both as a physical additive as well as part of the polymer structure. Acid forming phosphorus compounds are generally effective in cotton and other cellulosic. Acidic retardants produce char via a dehydration process and this brings about the final fire-retardancy in phosphate-containing composition. High efficiency of phosphorus fire retardants in polyurethane foam has also been suggested to be the result of stable char formation. The char affects the flammability in the three following ways: reduction of flammable fuel, insulation by the char and coating by the non-volatile thermally stable phosphorous acids which screen the hot carbon from the oxygen. Nitrogen-phosphorus synergism in cellulose in controversial and evidence indicates that it is non existent in polymers.     

Effects of mechanical properties of polymer on ceramic-polymer composite thick films fabricated by aerosol deposition

ABSTRACT: Two types of ceramic-polymer composite thick films were deposited on Cu substrates by an aerosol deposition process, and their properties were investigated to fabricate optimized ceramic-based polymer composite thick films for application onto integrated substrates with the advantage of plasticity. When polymers with different mechanical properties, such as polyimide (PI) and poly(methyl methacrylate) (PMMA), are used as starting powders together with α-Al2O3 powder, two types of composite films are formed with different characteristics - surface morphologies, deposition rates, and crystallite size of α-Al2O3. Through the results of micro-Vickers hardness testing, it was confirmed that the mechanical properties of the polymer itself are associated with the performances of the ceramic-polymer composite films. To support and explain these results, the microstructures of the two types of polymer powders were observed after planetary milling and an additional modeling test was carried out. As a result, we could conclude that the PMMA powder is distorted by the impact of the Al2O3 powder, so that the resulting Al2O3-PMMA composite film had a very small amount of PMMA and a low deposition rate. In contrast, when using PI powder, the Al2O3-PI composite film had a high deposition rate due to the cracking of PI particles. Consequently, it was revealed that the mechanical properties of polymers have a considerable effect on the properties of the resulting ceramic-polymer composite thick films.     

A rapid approach to urushiol–copper(I) coordination polymer under UV irradiation

Urushiol–metal polymers have attracted more and more attention in China because of their wide applications as a heavy anticorrosive coating in chemical industry. They could also offer many novel properties, including catalytic activity, magnetic property, semiconductive properties, flame retarding performance, etc., and significant progresses have been achieved in synthesis and study on the mechanism of these polymers. In this paper, a rapid method for fabrication of urushiol–copper(I) coordination polymer was developed under UV irradiation within 2 min. The formation and thermo-stability of the cured films were characterized by ESR, XPS, FT-IR, TGA, etc. The results suggested the coordination occurred between copper(I) ion and oxygen under UV irradiation. In the course of UV irradiation, the hydroxyl groups on the phenyl ring of urushiol were dissociated to urushiol semiquinone, and then coordinated with copper(I) ions generated by deoxidization of copper(II) ion. At the same time, crosslinking reaction on the long aliphatic unsaturated side chain occurred to form polymer. TG analysis showed that the polymer had excellent thermo-stability.     

环保型阻燃PC的研究进展

聚碳酸酯(PC)具有优异的力学性能、良好的电性能、较宽的使用温度范围,广泛应用于电子电气、汽车、建筑等行业,通常有阻燃及环保要求。PC中常用的阻燃剂有溴系、有机磷系、磷腈类、硅系和磺酸盐类阻燃剂。随着欧盟RoHS指令和REACH法规的实施,部分阻燃剂被禁用,环保且高效的PC阻燃剂也越来越受关注。综述了环保阻燃剂在PC中的最新应用进展,对实际的改性工作有一定指导意义。