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Electrospinning is a promising drying technology providing a rapid and gentle drying at ambient temperature, thus electrospinning of polyvinyl alcohol aqueous solutions was investigated for the solid formulation of biopharmaceuticals. The commonly used single-needle electrospinning does not have adequate productivity to satisfy the industrial requirements, therefore our aim was to study the scale-up of the technology by using high-speed electrospinning. High molecular weight polyethylene oxide as a secondary polymer was applied to enhance the fiber formation of polyvinyl alcohol. While polyvinyl alcohol-polyethylene oxide formulations resulted in adequate fiber formation it was not possible to process them further as the friability of the fibers was too low. In order to increase the friability, the effect of adding various sugars (mannitol, glucose, lactose, saccharose, and trehalose) was investigated. The results showed that mannitol was the best friability enhancing excipient because of its crystallinity and low moisture content in the fibrous sample. In contrast, glucose, lactose, saccharose, and trehalose were amorphous with higher moisture content and fibers containing these were grindable only after post-drying.

Polymer-based electrospun amorphous solid dispersions (ASDs) were prepared and investigated from pharmaceutical application point of view. Spironolactone (SPIR) was used as model drug mixed in various concentrations with polymers suitable for fibre formation, such as vinylpyrrolidone-vinyl acetate copolymer, polyvinylpyrrolidone K30 and hydroxypropyl methylcellulose. Single needle electrospinning was applied at first for screening the composition of the prepared ASDs. Scaling-up the selected polymer-drug combination was accomplished by high speed electrospinning, the productivity of which enabled investigation of downstream processing to generate tablet formulation. The steps of a potential continuous production line (fibre collection, grinding, feeding and tableting) proved to be feasible with the electrospun ASD without any sign of crystallization. If crystalline drug was added into the ASD containing tablets as impurity strictly monotonous decrease of drug dissolution was observed in the function of the crystalline drug content. The capabilities of the non-destructive Raman and near-infrared spectroscopies, as fast quality assurance tools, were compared to each other in quantifying of crystalline SPIR content in the prepared tablets.

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The aim of this work was to investigate the suitability of electrospinning for biodrug delivery and to develop an electrospinning-based method to produce vaginal drug delivery systems. Lactobacillus acidophilus bacteria were encapsu- lated into nanofibers of three different polymers (polyvinyl alcohol and polyvinylpyrrolidone with two different molar masses). Shelf life of the bacteria could be enhanced by the exclusion of water and by preparing a solid dosage form, which is an advantageous and patient-friendly way of administration. The formulations were stored at -20, 7 and 25°C, respec- tively. Viability testing showed that the nanofibers can provide long term stability for huge amounts of living bacteria if they are kept at (or below) 7°C. Furthermore, all kinds of nanowebs prepared in this work dissolved instantly when they got in contact with water, thus the developed biohybrid nanowebs can provide new potential ways for curing bacterial vagi- nosis.

This study compares a wide range of potentially synergistic flame retardant combinations in thermoplastic polyurethanes, applying both additive and reactive formulations. After preliminary screening based on LOI and UL-94 results, the best additive and reactive systems were subjected to detailed (thermogravimetric, cone calorimetric, mechanical and rheological) analysis and were compared to the reference TPU and a flame retarded benchmark TPU system.

A novel evaluation method was developed for Raman microscopic quantitative characterization of polymerwaste. Car shredder polymer waste was divided into different density fractions by magnetic density separation (MDS) tech -nique, and each fraction was investigated by Raman mapping, which is capable of detecting the components being presenteven in low concentration. The only method available for evaluation of the mapping results was earlier to assign each pixelto a component visually and to count the number of different polymers on the Raman map. An automated method is pro-posed here for pixel classification, which helps to detect the different polymers present and enables rapid assignment ofeach pixel to the appropriate polymer. Six chemometric methods were tested to provide a basis for the pixel classification,among which multivariate curve resolution-alternating least squares (MCR-ALS) provided the best results. The MCR-ALSbased pixel identification method was then used for the quantitative characterization of each waste density fraction, whereit was found that the automated method yields accurate results in a very short time, as opposed to manual pixel countingmethod which may take hours of human work per dataset.

Upgrading of polypropylene waste was performed by different composite technologies, in order to improve the flame retardancy combined with preserved or improved mechanical properties. The polymer waste of density below 900 kg/m 3 is originated from end-of-life vehicles (ELV) after comminution, density separation and comprehensive analy- sis. Intumescent flame retardant system was used for reducing the flammability; while chopped glass fibre reinforcement was used to compensate the deterioration of mechanical properties caused by flame retardant additives. In mixed composite beside of flame retardants, the reinforcement effect of glass fibre can not be realized; therefore with modification of com- posite structure (but maintaining the composition) a multilayer composite was developed, which contains 65.5% of recy- cled polymer, where the core is reinforced with glass fibre covered by flame retarded shell layers. Enhanced flame retardancy (4 min longer time to escape) was achieved by using this layered composite compared to the mixed composite, thus the time to escape could be extended only with modification of composite structure.

The applicability of phosphorus-containing reactive amine, which can be used in epoxy resins both as crosslinking agent and as flame retardant, was compared in an aliphatic and an aromatic epoxy resin system. In order to fulfil the strong requirements on mechanical properties of the aircraft and aerospace applications, where they are mostly supposed to be applied, carbon fibre-reinforced composites were prepared. The flame retardant performance was characterized by relevant tests and mass loss type cone calorimeter. Besides the flame retardancy, the tensile and bending characteristics and interlaminar shear strength were evaluated. The intumescence-hindering effect of the fibre reinforcement was overcome by forming a multilayer composite, consisting of reference composite core and intumescent epoxy resin coating layer, which proved to provide simultaneous amelioration of flame retardancy and mechanical properties of epoxy resins.

A mathematical model, simulation results and laboratory experiments are reported to describe the degradation of fire retardant polymeric materials. The model describes the heat and mass balances of a polymer layer with finite thickness. The degradation is initiated by a constant heat flux at the top of the layer. It is assumed that the polymer degrades to a fixed mass of char and volatile gas in an instantaneous step, at the moment when the temperature reaches a critical value. The most important heat transport mechanism is conduction, which dominates the temperature profile. The mass transport of gas is described by Darcy's law, with a simplifying condition that the overall solid volume is constant during degradation. The transport processes have been modelled in one spatial dimension. Calculations and experiments have been carried out to establish the effects of critical parameters such as layer thickness, heat flux and material properties.

Flame retarded thermoplastic polymer compounds were prepared containing recycled rubber tyres, low density polyethylene, ethylene vinyl acetate copolymer and an intumescent additive system consisting of waste polyurethane foam and ammonium polyphosphate. The effect of the additives on the combustion properties was characterised by Limiting Oxygen Index, UL 94 and mass loss calorimetric measurements. The environmental impact was estimated by determining the gas components of CO2 and CO evolving from the compounds during the burning process using a gas analyser system constructed by coupling an FTIR unit to a mass loss calorimeter. The new material forms a thermoplastic rubber of excel- lent processability making it suitable for application in construction industry.

Flame retardant effect of newly synthesized phosphorus-containing reactive amine, which can be used both as crosslinking agent in epoxy resins and as flame retardant, was explored. The effect of montmorillonite and sepiolite additives on thermal stability and flame retardancy was compared in the epoxy resin matrix. Copyright © 2006 John Wiley & Sons, Ltd.

Interface modifications optimized for fire retardancy require detailed research. Confocal Raman microscopy was used to analyze the degradation locally in the area of the nanotube and clay additives. The double-walled carbon nanotube (DWCNT), containing Co catalyst residue, accelerates the deacetylation process of poly(ethylene-co-vinylacetate) (EVA) considerably, while the montmorillonite (MMT) has no significant influence under static circumstances. The compounding process influences the effect of MMT, which causes partial crosslinking in EVA during the compounding. This mechanochemical reaction is catalyzed by uncovered MMT particles, while organophillized MMT promotes the charring process. Inorganic surface modification with various metal ions has also some stabilizing effect. Spray drying of MMT results in microparticles of increased surface area and improved thermal stability of the EVA system. The lowest rate of flame spreading was achieved using uncoated MMT, while coating with cationic surfactant was most efficient for hindering dripping. The rate of heat release (RHR) of the organically modified and the spray dried MMT was approximately the same. The combined organic-inorganic modified clay moderates both the dripping and the flame spreading in the EVA. Copyright © 2006 John Wiley & Sons, Ltd.

Common consideration and classification of surface and interface phenomena in wide areas of material science are discussed through three examples: basalt fiber reinforced composite; flame retarded polypropylene and polyorganosiloxane nanocomposite. Interface-related characteristics of polymer composites and biomaterials are discussed using uniform principles. A new classification of the interphases is introduced including the compatible, adaptive and smart interfacial layers. In case of basalt fiber reinforced polypropylene reactive interface modification is performed in a new and economic way using reactive surfactants. These additives accomplish the compatibilization of the phases during reactive compounding/processing. The fire retardancy of polypropylene system containing ammonium polyphosphate and clay nanoparticles is enhanced by adaptive polysiloxane interphase. Clay additive provides thermal and pH responsive character to silicone based biomaterial thus it can be applied for forming smart interphases.

The efficiency of ammonium polyphosphate in different biocomposites was compared. For the comparison flame retarded lignocellulosic filler reinforced biocomposites were prepared using polypropylene (PP), polyurethane (PUR) and fully biodegradable starch matrices. The compatibility of wood flake with PP was improved by application of an alkoxy silane based reactive surfactant. The silylation improved not only the compatibility but also the thermal stability of the wood flake according to TG measurements. Raman spectroscopic analysis of the silylated product showed that the improved thermal stability is the result of reduced ratio of the amorphous phase of cellulose. The phosphorus additives in flame retarded PUR biocomposites, comprising waste bio fillers and recycled polyol, proved to be very effective because both the matrix and the filler components participate in mechanism of flame retardancy. Plasticised thermoplastic starch could be flame retarded efficiently by as little as 10% ammonium polyphosphate. After their service life the biocomposites can be utilised as chemical fertilizer.

The deterioration of naturally aged low-density polyethylene (LDPE) film was observed by elongation properties, DSC melting enthalpies and surface geometric characteristics by use of atomic force microscopy (AFM). The decrease of elongation at break under the influence of ageing was in good accordance with the increase of melting enthalpies and both phenomena could be explained by the gradual decrease of molecular mass of the polymer. On the wavy surface with a wavelength range of 10–15 μm, valleys with amplitudes from 160 to 600 nm could be observed by AFM depending on the time of ageing. The increase of deepness of valleys was explained not by the gradual erosion of the degraded surface but by the gradual increase of crystallinity, consequently the gradual shrinking on the surface of the polymer film. The gradual increase of crystallinity in the surface region of the film could be demonstrated by confocal Raman microscopy.

This article deals with the study of the efficiency of different compatibilizing agents in the intumescent polypropylene/polyamide-6/ammonium polyphosphate (PP/PA-6/APP) blend. The migration of additive was first investigated by X-ray photoelectron spectroscopy. The study showed that ethylene–butyl acrylate–maleic anhydride is not efficient in preventing the exudation of APP to the surface. However, ethylene vinyl acetate (EVA) prevented such a phenomenon. Second, the modifications in the blends were analyzed as a function of their compositions. Optical microscopy analysis showed that adding EVA to PP/PA-6/APP promoted a decrease in the size of PA-6 droplets. X-ray diffraction was used to characterize the effect of each component on the PP crystallinity. It was clearly shown that the crystallinity depends on the composition of the blend. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 402–411, 2004

Multilayer systems consisting of flame retarded and reinforced layers of recycled polymer were formed. The structure and the thickness of the interfacial layer between the phases were analysed by Differential Scanning Calorimetry and Raman microscopy. The sequence order of the layers was varied for achieving improvement in both the flame retardancy and mechanical performance of recycled polymers and for obtaining upcycled product this way. Investigation of injection moulded and compression moulded products demonstrated the advantage of reinforced core and flame retarded shell over the opposite structure. The multilayered structure was found an economic way for producing recycled polymer materials of improved fire resistance, flexural strength and modulus.

Basalt fibers, similarly to other silicate fibers, can be introduced into both thermoplastic and thermosetting polymer matrices. In this work some basalt fiber reinforced polypropylene composites were investigated. The fiber-matrix adhesion was improved by commercial and non-commercial maleic anhydride derivatives. The latter types, called reactive surfactants, were prepared in laboratory scale and the progress of the syntheses was determined by Raman microscopy. The additives allowed performing reactive interface modification during the compounding process. Due to the interface modification with the additives in low concentration the mechanical properties improved. The boundary layers on the surface of the reinforcing fibers were observed using scanning electron microscopy (SEM).

The Raman microscope is one of the most convenient instruments for analyzing the structural characteristics and changes in the interfacial region of multicomponent systems. This is confirmed by the results obtained in the field of packaging materials, nanocomposites, and basalt fibre reinforced composites. In the course of this study, the chemical character of the surface and interfacial regions were investigated and, in addition, the local characteristics of the crystallization process of the polymer matrix could be determined.

Polypropylene-based composites were prepared containing non-treated and various treated cotton fibre and wood flakes. A correlation was observed among the fibre treatment and compounding parameters, mechanical and discoloration properties. The structural changes in fibres were demonstrated by Raman spectroscopic and DSC measurements. The possibility for forming cellulose fibre containing flame retardant composites was also investigated. The efficiency of various treatments on compounding, discoloration and mechanical properties enhance in the following order: no treatment < non ionic surfactant < reactive silicone segment containing non ionic surfactant < special silylation treatment. The best results obtained with the special silylation treatment were explained with the more organophilic character and by the thermal stability of the treated fibres. Cellulose fibre as a polyol-charring component and ammonium-polyphosphate together constitute a high performance intumescent flame retardant system in the PP matrix.

Addition of Ammonium Polyphosphate/Polyamide-6 system is known to provide flame retardancy in many polymers blends via an intumescent process. Particulate fillers (talc and calcium carbonate) are used in large quantities in PP. Combination of fillers in PP can modify the properties of the polymeric matrix. This study investigates the effect of fillers (talc and calcium carbonate) on the fire performance of the Polypropylene/Ammonium polyphosphate/Polyamide-6 blend. It is shown that the fire performance strongly depends on the nature of the filler used. Talc increases and calcium carbonate decreases in the fire performance of the blend.

The effects of fillers (talc and calcium carbonate) were investigated on polypropylene /ammonium polyphosphate/polyamide-6 (PP/APP/PA-6) intumescent system by using mechanical testing, LOI method, cone calorimetry and thermoanalytical techniques. Calcium carbonate and talc affect the fire protective properties of PP/APP/PA-6 system in different ways. It is shown that talc induces an increase in the Young's modulus and a decrease in the elongation at break. Calcium carbonate leads to a decrease in the elongation at break, but there is no improvement in the Young's modulus. Talc increases fire protective performance due to forming a ceramic like protective shield at the surface, whereas calcium carbonate decreases it because of a reaction with APP. Effects of talc and calcium carbonate were furthermore investigated on PP/APP/PA-6 system by measuring Rate of Heat Release (RHR), Total Heat Emitted (THE), CO/CO 2 evolution and residual mass. Results are interpreted by means of decomposition, chemical reaction between components and formation of a protective shield at the surface at ignition.

Monophosphorylated hydroxy phenols were synthesized in a selective way and incorporated in different percentages into epoxy resins as reactive flame retardants. The LOI values of the epoxy resin samples could be increased this way up to 28%. The DSC results show that by increasing the percentage of incorporated monophosphorylated hydroquinone (HMP), the exothermic effect of the curing is decreased, which implies lower network density. An optimum balance is necessary between the flame retardant effect, determined by percentage of HMP, and the lower degree of crosslinking.

Montmorillonite nanoparticles were found to be inefficient in polypropylene because of the lack of a heat insulating char layer and the decomposition of the compatibilising surfactant layer on their surface. Combination with an ammonium polyphosphate-based intumescent system showed some synergism due to modified rheology. The effect of surface and interface modification was analysed using Raman microscopy and X-ray photoelectron spectroscopy. Forming a heat resistant coating layer of low surface energy around the nanoparticles promotes their migration to the surface and formation of a flexible barrier layer, and thus leads to better performance.

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The principle of multilayer interphases was proposed earlier for modifying the mechanical properties and UV stability of various multicomponent polymer systems. This paper focuses on the applicability of this principle for improving the performance of intumescent flame-retardant systems using melamine-treated ammonium polyphosphate, silicone modified polyol + ammonium polyphosphate, and silicone modified nanoparticles in polypropylene. The structure–property relationship of the formed systems was studied. A melamine layer of 1.45 nm thickness was formed around ammonium polyphosphate in order to improve the hygrothermal stability, but this layer was not shear-resistant enough. An interphase formed using a special silicone additive is more stable and acts with the intumescent flame-retardant system synergistically. The advantageous interfacial structure is quite complex in this case: polyphosphate particles are surrounded with a macromolecular layer formed from polyol, silicone, and reactive surfactant in order to ensure good stability, efficiency and compatibility. AFM, XPS and a Cone Calorimeter were used for determining the structure and flame-retardancy of these systems. Nanocomposites combined with silicone-containing intumescent system were developed in order to avoid dipping at ignition in the vertical position. SAXS and µ-TA methods were used for determining the structure of this material. Copyright ­© 2003 John Wiley & Sons, Ltd.

Mg(OH)2 and ammonium polyphosphate (APP) based flame retarded polyethylene (PE) and polypropylene (PP) compounds were prepared in a plastograph and the influence of additive systems on the microstructure, mechanical, and melt characteristics of the compounds was investigated by DSC, Raman microscopy, and rheological measurements. A high loading of Mg(OH)2 has a nucleating and crystallinity reducing effect in low density PE. The crystallinity reducing effect was explained by formation of a partially ordered but noncrystallized interfacial region around the flame retardant (FR) particles. The nucleating effect was hindered when the particles were embedded in elastomer. The nucleating effect of APP in PP was also reduced when a polyol layer surrounded it. The incorporation of boroxo siloxane (BSil) elatomer FR synergist, introduced additionally to the above additives, resulted in a further nucleating effect, and increased the melt viscosity. Polymer layered montmorillonite, applied instead of BSil elastomer,...

A model system of intumescent flame retardants, consisting of ammonium polyphosphate and pentaerythritol was prepared and investigated in polypropylene and without the polymer matrix. Thermal scanning oscillation rheometric investigation in the temperature range of 170–500 °C was used to detect the rheological behaviour in the region of melting of the polymer and the plasticity of the char formed at higher temperature. Addition of boroxo siloxane to the model system caused advantageous changes in both regions. Increased complex viscosity and viscoelsasticity of the melt and char respectively contributes to better flame retardancy. According to DTG and FTIR studies the reactions of boroxo siloxane with pentaerythritol and ammonium polyphosphate are the reasons for the rheological changes.

Optimal concentration of boroxo siloxane elastomer synergist was determined by LOI and cone calorimetric measurements on ammonium polyphosphate and pentaerythritol containing intumescent flame retardant for polypropylene. The increased viscosity of the melt and plasticity of intumescent char due to boroxo siloxane elastomer could be proved by a thermal scanning rheometric investigation. It is presumed, the increased melt viscosity is created by the product of boroxo siloxane-pentaerythritol, formed during the compound preparation, while the improved char plasticity is the result of product formed at high temperature from boroxo siloxane and ammonium polyphosphate.

The deterioration of differently stabilised and pigmented high density polyethylene films was investigated by DSC and UV spectroscopy methods in the course of accelerated photo-ageing and compared to earlier XPS and gel-content results. Unexpectedly quick destruction of phthalocyanine containing film was observed and explained by the adsorptive removal of the stabiliser from the polymer matrix. In the pigment (filler)-solvent-stabiliser model systems the high susceptibility of hindered phenol type heat-stabiliser to adsorb on talc and phthalocyanine pigment was proved by UV spectroscopic measurements. Surface coating of the talc and pigment with a reactive surfactant considerable reduced the adsorption capacity and thus improved the photo-stability of the pigmented film.

pharmaceutical technologies is one of the most exciting examples of the cross-fertilization tendencies within the materials science in the 21st century. The extended use of polymers and the composite structure in solid pharmaceuticals should have been induced it earlier but the conservative approach (based on safety arguments) of pharmacists hindered the spread of continuous processes in this field. The next decades will, however, bring about the technology of pharmaceutical plants getting closer to that of the plastic factories. The roots of this change, i.e. pharmaceuticals produced by extrusion and electrospinning, appeared already in the scientific literature and patents. The innovation in the pharmaceutical industry can be accelerated this way rather than by the expensive development of new drugs. The current task is to clarify the advantages of such interdisciplinary cooperation. The last step of the synthesis (crystallization) is expected, for example, to be integrated with continuous formulation processes in the pharmaceutical plant of the future. Positive feedbacks of this radical change to the plastic industry can be noticed already nowadays. Special types of polylactic acid, polyhydroxybutyrate and other biodegradable polymers, the larger scale application of which was hindered by economic reasons, have found substantial market share in the pharmaceutical industry. After recovery of the investment costs these polymers can spread out in the plastic industry in optimized and well-controlled way. The remaining task is the development of specific functional properties, such as the fire retardancy. Investment in the supercritical extrusion is also expected for pharmaceuticals, the heat sensitivity of which needs this gentle technology badly. These developments, coupled with inline process control (required by real time release) will provide very positive influence to the traditional plastic industry as well. In-line process control accompanied by total management and continuous development of the technology, called ‘Process Analytical Technology (PAT)’, need the application of recently developed advanced mathematical (chemometric) algorithms, which, on the other hand, have been proven to be very useful tools for spectroscopic identification and classification of components of mixed polymer wastes.

The rapidly growing polymer market increases the risk of fire. The competition for reducing the costs and the activities for increasing the recyclability are advantageous from many aspects but promote the use of cheap and flammable polymers. The relative amount of the types of fire retardants (FRs) used in polymers is changing. The halogen containing compounds initiate corrosion, furthermore, some of them proved to be harmful to the environment and human health. Therefore the new European regulations promote the substitution of some conventional flame retardants by environmental-friendly ones. Reactive processing methods bond the additives to the polymer chains thus provide solution against their release to the environment, which is critical especially for some potential pseudohormones. Beyond the increasing importance of reactive methods the nano-concept is the most widely investigated novel approach to fire retardancy. Promising is the low environmental impact of nanofillers and influence on the macromolecular arrangement owing to their high surface area (reducing the heat distortion and melt dripping at high temperature). However, their fire retardancy performance should be enhanced, which requires better understanding of the mechanism of their action. It has to be clarified what is the relative role of their catalytic and physical action. The importance of the geometric dimensions, quality of dispersion and the potential synergism between different types should be clarified as well. Furthermore, the undesirable by-effect of removing stabilizers from the polymer matrix through their high surface area has to be eliminated. Most recent concepts are the in situ formation of nanofillers (during extrusion of the polymers) and of FR-active interfaces or surfaces around inclusions. Advancement of these concepts require the development of new micro-scale fire modeling/testing methods. Based on the described research activities increasing use of reactive, halogen free solutions in combination with nanofillers of well designed interfaces are predicted. Economic approaches applying recycled polymer matrices, nanofillers and multifunctional additives will increase in the close future. A multifunctional flame retardant can be applied for example as adaptive interlayer in a multiphase systems facilitating good mechanical, transport or adhesive performance at ambient temperature and transforming to protective (heat and combustiblegas barrier) layer at the temperature of combustion.

A mechanistic scheme is suggested for lactam polymerisation initiated by hydrochloric acid on the basis of the general mechanism put forward earlier by Bertalan et al. According to this mechanism during the polymerization conditions are created which can initiate further polymerizations resulting in a characteristic inflection type kinetic curve. Experimental results can be well interpreted qualitatively on the basis of this mechanism, and therefore it can serve as a starting point also for a quantitative kinetic model.

One way to improve the fire performance of polymers is by the development of intumescent systems. The addition of ammonium polyphosphate/polyamide-6 is known to provide flame retardancy in many polymers via an intumescent process. The development of appropriate formulations is limited by their mechanical properties. This study shows that polypropylene based intumescent blends are efficient fire retardant systems and that acceptable mechanical properties can be obtained. It is also shown that adding talc improves the mechanical properties of intumescent polypropylene formulations without decreasing their fire retardancy.