Search

Thermoplastic starch (TPS) consisting of corn starch and glycerol as a plasticizer, and TPS-montmorillonite (MMT) nanocomposite were stored at room temperature in the air with relative humidities (RH) of 11, 55 and 85% for seven weeks. Mechanical testing and dynamic mechanical thermal analysis (DMTA) were performed to detect changes in their mechanical properties. Solid-state NMR spectroscopy monitoring the changes in molecular mobility in the samples provided an insight into relations between mechanical properties and local structure. The results of mechanical testing indicated that the addition of MMT results in the increase in the tensile strength and Young’s modulus while elongation at break decreased, indicating the reinforcing effect of MMT. DMTA experiments revealed a decrease in glass transition temperature of starch-rich phase below room temperature for samples stored at higher RH (55 and 85%). This indicates that absorbed water molecules had additional plasticizing effect on starch resulting in higher mobility of starch chain segments. Recrystallization in these samples was deduced from the shape of cross-polarization magic-angle spinning 13C NMR spectra. The shape of broad-line 1H NMR spectra reflected changes in molecular mobility in the studied samples during seven weeks of storage and revealed that a high amount of water molecules impacts the starch intermolecular hydrogen bond density.

The work deals with the application of biopolymer fillers in rubber formulations. Calcium lignosulfonate was incorporated into styrene–butadiene rubber and acrylonitrile–butadiene rubber in a constant amount of 30 phr. Glycerol in a concentration scale ranging from 5 to 20 phr was used as a plasticizer for rubber formulations. For the cross-linking of the compounds, a sulfur-based curing system was used. The study was focused on the investigation of glycerol in the curing process; the viscosity of rubber compounds; and the cross-link density, morphology, physical–mechanical, and dynamic mechanical properties of vulcanizates. The study revealed that the application of glycerol as a plasticizer resulted in a reduction in the rubber compounds’ viscosity and contributed to the better dispersion and distribution of the filler within the rubber matrices. The mutual adhesion and compatibility between the filler and the rubber matrices were improved, which resulted in the significant enhancement of tensile characteristics. The main output of the work is the knowledge that the improvement of the physical–mechanical properties of biopolymer-filled vulcanizates can be easily obtained via the simple addition of a very cheap and environmentally friendly plasticizer into rubber compounds during their processing without additional treatments or procedures. The enhancement of the physical–mechanical properties of rubber compounds filled with biopolymers might contribute to the broadening of their potential applications. Moreover, the price of the final rubber articles could be reduced, and more pronounced ecological aspects could also be emphasized.

Mixtures of poly(butylene-adipate-co-terephthalate) (PBAT) with thermoplastic starch (TPS) in a broad concentration range from 70:30 to 30:70 wt.% were prepared in a twin-screw extruder. Mechanical...

A procedure is described of grafting the acrylic acid onto an oxygen/ozone-activated metallocene poly(ethylene-co-propylene). Consequently, the grafted copolymer is applied as a component in a metallocene polyolefin-based hot-melt adhesive composition with increased adhesion. The surface properties and adhesion strength of the prepared hot-melt adhesive (HMA) were determined and used to account for the effect of grafting. The application of grafted polyolefin as one of the components of the HMA mixture provides significant increase in adhesive strength, and it also results in increased compatibility and negligible effects on the technological parameters of the final composition. The obtained results may have significant impact for the practical application of prepared HMA for book bonding.

Conductive polymer composites (CPC) from renewable resources exhibit many interesting characteristics due to their biodegradability and conductivity changes under mechanical, thermal, chemical, or electrical stress. This study is focused on investigating the physical properties of electroconductive thermoplastic starch (TPS)–based composites and changes in electroconductive paths during cyclic deformation. TPS–based composites filled with various carbon black (CB) contents were prepared through melt processing. The electrical conductivity and physicochemical properties of TPS–CB composites, including mechanical properties and rheological behavior, were evaluated. With increasing CB content, the tensile strength and Young’s modulus were found to increase substantially. We found a percolation threshold for the CB loading of approximately 5.5 wt% based on the rheology and electrical conductivity. To observe the changing structure of the conductive CB paths during cyclic deformation, both the electrical conductivity and mechanical properties were recorded in parallel using online measurements. Moreover, the instant electrical conductivity measured online during mechanical deformation of the materials was taken as the parameter indirectly describing the structure of the conductive CB network. The electrical conductivity was found to increase during five runs of repeated cyclic mechanical deformations to constant deformation below strain at break, indicating good recovery of conductive paths and their new formation.

The performance of European Union in terms of R&D investment, innovations, and educational attainments generally lags behind that of its main competitors - the United States and Japan. Within the EU, the new member states from Central and Eastern Europe belong to the group of moderate innovators. As technology is the key component of the innovation system of the 2nd generation, this paper is dedicated to discussing the methods of technology transfer applied by innovation leaders in the EU (e.g. Germany or Finland) and to identifying the factors that may represent the main stumbling blocks in the way of more effective innovation procedures in the new member states (e.g. Governments´ preferences for FDI that is attracted by the relatively cheap and skilled labour force; investors´ preferences for using know-how developed in their home countries; the absence of venture capital available for R&D and technology transfers, etc.). As the situation in the new member states begins to change - wages are growing and the countries are building new research infrastructure with the help of the EU funds - a new innovation and TT paradigm enters the stage. We discuss the ways of coping with these new challenges – such as better governance in the field of patents, extended education of students in the field of innovative competences and entrepreneurial skills, deeper understanding of the operations of industry technology transfer organizations and improved access to venture capital.

The grafting of metallocene ethyle-octene copolymer to higher polarity with acrylic acid. Metallocene polyolefins (MePO) were grafted in melt due to increasing their surface free energy and adhesive properties. MePO modification with ozone was used to initiate the creation of peroxides on the surface of the polymer with subsequently grafting of acrylic acid in polymer melt. The efficiency of grafting in melt is high, ranging between 0.77 and 0.97.

1H and 13C NMR spectroscopy was used for the study of corn starch plasticized with urea and/or glycerol. The information on the interactions between plasticizers and starch macromolecules as well as the arrangement of starch macromolecules depending on the storage time (from 1 day to 52 weeks), were obtained from the broad-line and magic-angle spinning 1H NMR spectra measured at 22 °C and within the range from 30 to 140 °C and the cross-polarization magic-angle spinning (CP MAS) 13C NMR spectra measured at 30 °C. The 1H chemical shifts for the groups of the plasticizer molecules enabled characterization of the interactions between urea and glycerol molecules in starch plasticized with a mixture of urea and glycerol. With increasing temperature, the signal related to water molecules gradually vanished due to water evaporation, and resolved 1H peaks associated with starch macromolecules were detected above 100 °C. The free water amount in the thermoplastic starch samples was also estimated using MAS 1H NMR spectra. Formation of double helices due to sample ageing was observed through the CP MAS 13C NMR spectra.

Materials based on mixture of poly(butylene adipate-co-terephthalate) (PBAT) with thermoplastic starch (TPS) were investigated concerning mechanical properties and structure characterized by DMTA and SEM. TPS plasticized with two different plasticizers were tested, namely glycerol and urea. It was found that TPS with urea exhibits significantly higher tensile strength and modulus than TPS with starch plasticized by glycerol and this affects also the properties of mixtures PBAT/TPS. Tensile strength of mixtures containing 20% of both kinds of TPS is substantially lower than virgin PBAT but the strength for mixture with 50% of TPS with urea is approaching to the value for neat PBAT while the same content of TPS/glycerol leads to further decrease in stress. Differences in moduli for PBAT with TPS/urea and TPS/glycerol represent one order of magnitude. The reason for this behavior consists in much stronger interactions between urea and starch hydroxyl groups compared to glycerol resulting in prevention of void formation visible on fracture surfaces (SEM) and higher glass transitions temperature (DMTA).

Modification of wood by radio-frequency discharge plasma. Low-temperature plasma was used to improve the surface and adhesive properties of wood. The pre-treatment of wood surfaces using radio-frequency (RF) discharge plasma is attractive for various wood applications, mainly because of the high efficiency and low production cost of the process. The treatment of wood by RF plasma exhibited an aging effect, with the modified surface never recovering its initial hydrophobic state. The contact angle of water decreased with the activation time of the RF plasma treatment.

Changes in mechanical and thermal properties of biodegradable mulches based on plasticized PLA/PHB filled with 3 wt% of carbon black were investigated during natural ageing in real soil environments after application for one season. The natural ageing process changes were evaluated under three different conditions of the mulching films: (a) buried in the soil, (b) exposed to sunlight, and (c) shadowed by plants. In a parallel study, the film was irradiated by a UV–Vis lamp under laboratory controlled test conditions at constant temperature and humidity. All samples were analyzed using GPC, DSC, DMTA and tensile tests. The plasticized PLA/PHB/CB film buried in soil lost its tensile properties faster than when shadowed by plants or exposed to sunlight. The deterioration of mechanical properties during degradation resulted in significant decreases elongation at break, while Young’s modulus values and tensile stress increased. Assessment of the mulching effect on the harvest of sweet pepper fruits, as well as carotenoids and vitamin C contents, was also performed. The obtained results showed that plasticized PLA/PHB/CB film has the potential for application for one season mulches.

Grafting of metallocene ethyle-octene copolymer to higher polarity with acrylic acid. Metallocene polyolefins (MePO) were grafted in melt due to increasing their surface free energy and adhesive properties. MePO modification with ozone was used to initiate the creation of peroxides on the surface ofthe polymer with subsequently grafting of acrylic acid in polymer melt. The grafting efficiency of grafting in melt is high and varies between 0.77 and 0.97.

Conventional polymers are made from fossil resources and consume fossil energy in their production, yielding CO2 emissions. Production of large-volume compounds from CO2, either from point sources ...

This study is focused on enhancing the stability of mechanical and chemical properties of thermoplastic starch (TPS) by dual crosslinking strategy through melt processing conditions. The dually crosslinked TPS was prepared by in situ reaction of starch, glycerol, and epichlorohydrin (ECH), resulting in both noncovalent and covalent bond formation. The TPS was characterized by tensile testing, dynamic mechanical analysis (DMTA), rheology, and solubility in water. A substantial increase in tensile strength, Young's modulus, insoluble portion, and stability in water for dually crosslinked TPS was observed in comparison with conventional TPS. The rheology results indicated that the ECH induced the formation of 3D networks and significantly limited the chain mobility of the melted TPS, resulting in an extended relaxation process, which was also verified by DMTA. The suggested strategy avoids any chemical modification pretreatment of starch for introducing covalent bonds into TPS before one-step mixing using the melt processing technique.

We propose a method for developing an Energy Activated External Thermal Insulation Composite System (En-ActivETICS) for smart building envelopes that guarantees the required performance, durability, and service life of the building. The En-ActivETICS combines the traditional ETICS with phase change material (PCM) and flexible photovoltaics (FPV). These combined materials will become multifunctional, playing the roles of thermal insulator, heat accumulator, and energy generator with PCM lowering the temperature of FPV and therefore, increasing their efficiency. The En-ActivETICS is a new step in the development of building facade technology enabling to achieve a component that is classified as a functional material. The main result reported in the paper is the proposed method, which improves the existing technical approval guidelines for ETICS, entitled ETAG 004, when thermally activated components are added to the system. The method proposes research activities necessary to determine whether the novel wall system is in line with the essential requirements set to a building by the Construction Products Regulation. When tested according to the proposed method, a wall system should be comprehensively tested and technically documented active thermal insulation system that is aimed to give better building performance in terms of indoor environment, energy efficiency, and aesthetics.

Commercial metallocene ethylene–octene random copolymer, Resinex PE RXP 1502 (RXP), was grafted with acrylic or crotonic acid in the solution and in the melt to increase the RXP’s polarity and adhe...

Two natrified montmorillonites of different origin and three organomodified fillers (including two non-commercial experimentally prepared) were investigated either in dispersions in various solvents or in mixtures with three polymeric matrices. Rheological measurements of filler dispersions in solvents were used as a tool for determination of the affinity of modified filler's surfaces towards substrates with various polarities. These data were used for the prediction of filler structure in polymer matrices. The measurements in various liquids provide a fast and rather simple tool to determine the suitability of particular filler for certain polymer. This approach is based on the Hildebrand solubility parameter (δ) where materials with similar values of δ are likely to be miscible. The same or similar solubility parameters of chosen solvents and polymers are taken as tool for selecting appropriate pairs polymer – solvent considering the compatibility with particular filler. The predictions made according to rheological data were confirmed with rheology of real nanocomposites of the respective fillers in three polymeric matrices, namely low density polyethylene, polyamide 12 and polycaprolactone and supported by comparison with results obtained by transmission electron microscopy (TEM) as commonly used method for characterization of polymer - clay nanocomposites.

Three biodegradable plastics materials, namely pure poly(l-lactide) (PLA), PLA with plasticizer triacetine (TAC) and the mixture PLA/polyhydroxybutyrate (PHB) and TAC were investigated concerning changes of physical properties due to biodegradation in compost at 58°C up to 16days. With rising time of degradation in compost, both number and weight molecular masses were decreasing progressively, but only marginal change of the polydispersity index was observed which indicates that biodegradation is not random process. FTIR spectroscopy revealed that in spite of the extensive decrease of molecular weight, no substantial change in chemical composition was found. The most significant modification of the spectra consisted in an appearing of the broad band in region 3100-3300cm-1, which was assigned to a formation of biofilm on the sample surfaces. This effect appeared for all three materials, however, it was much more pronounced for samples containing also triacetine. Measurement of changes in crystalline portion confirmed that amorphous phase degrades substantially faster compared to crystalline part. The plasticizer triacetine is disappearing also rather fast from the sample resulting besides other effect also in a temporary increase of Tg, which at the beginning grows almost to the value typical for PLA without plasticizer but later the Tg is decreasing due to substantial changes in molecular weight. Generally during composting, the samples keep shape for up to 8days, after that time the material disintegrates to rough powder.

Foamy phase-change materials (FPCMs) based on linear low-density polyethylene (LLDPE) blended with 30 wt.% of paraffin wax (W) were successfully prepared for the first time. The advantage of these materials is their double functionality. First, they serve as standard thermal insulators, and second, the paraffin wax acts as a phase change component that absorbs thermal energy (the latent heat) during melting if the temperature increases above its melting point, which ensures better heat protection of buildings, for instance, against overheating. The density of the porous fabricated FPCM was 0.2898 g/cm3 with pore content 69 vol.% and gel portion achieved 27.5 wt.%. The thermal conductivity of the LLDPE/W foam was 0.09 W/m.K, whereas the thermal conductivity of the neat LLDPE foam prepared under the same conditions was 0.06 W/m.K, which caused a higher porosity of approximately 92 vol.%. The FPCM absorbed or released approximately 22–23 J/g during melting or cooling, respectively, and the material was stable under thermal and mechanical cycling.

In this study, we report a novel and simple technique to synthesize water-insoluble nanocomposite macromolecule composed of graphene oxide (GO) nanosheets and β-cyclodextrin (β-CD) polymer. These nanocomposites were synthesized by the one-pot precipitation polymerization process via polycondensation of β-CD with epichlorohydrin (ECH) in an aqueous suspension of GO under alkaline condition. The obtained β-CD polymer/GO (CDP-ECH/GO) were characterized by thermal gravimetry, differential scanning calorimetry, infrared and Raman spectroscopies, high-resolution solid state 13C NMR, X-ray diffraction, electron microscopy (both SEM and TEM), and energy dispersive spectroscopy. Furthermore, the mechanism of CDP-ECH/GO nanocomposites formation is also discussed depending on the type of mixing device that has been used during polymerization. The swelling ratio of the nanocomposites as well as their absorption properties toward methylene blue (MB), phenol (PN), 1-naphtol (1-NPH) and 2-naphtol (2-NPH) have been determined. Increasing the GO content in the nanocomposites results in an increase of the adsorption capacity of the materials.

Investigation was made into the effect of plasma treatment on the release kinetics of the drug Temozolomide (TMZ) from thin, biodegradable polyester films, comprising polylactic acid (PLA) and poly...

• The effect of mixture of plasticizers glycerol and urea on properties of starch was investigated.

Initiation of crosslinking of polyamide-6 (PA6) by proton beam irradiation was investigated for a virgin material as well as for PA6 containing up to 5 wt% of triallyl cyanurate (TAC) as a crosslinking coagent. The gel point was found to be 144 and 40 kGy for virgin PA6 and for PA6 with 1 wt% of TAC, while for higher TAC content gel content was determined to be around zero absorbed dose. The ratio between crosslinking and scission of macroradicals formed by irradiation was found to be around 0.65 regardless on presence or absence of TAC and its concentration. The more detailed discussion on chemical processes as well as on final structure formation after irradiation is based on data from differential scanning calorimetry, detecting a decrease of both lamellar thickness and crystalline portion, but an increase of glass transition temperature.

Ageing of foils made from poly(lactic acid)/poly(3-hydroxybutyrate) PLA/PHB blends, unfilled or filled with 1 wt% of carbon black is presented. The foils were either buried in the soil or exposed to the sunlight for 4 months to imitate the behavior of the material when applied as mulching foils. In addition, UV-vis irradiation and hydrolysis over water vapor were studied under laboratory conditions. Finally, the effect of the ageing under the mentioned conditions on mineralization of the foils at room temperature was investigated in order to simulate plowing the material after its application. The degradation was studied by gel permeation chromatography and structural changes were investigated using differential scanning calorimetry. The changes in mechanical properties were investigated by dynamic-mechanical thermal analysis and a tensile test. Addition of carbon black to PLA/PHB resulted in improved photochemical stabilization of the foils, preventing supplemental crystallization during ageing and provided longer retention of the mechanical properties during ageing.

The 1H–13C cross polarization nuclear magnetic resonance technique was used for the study of molecular mobility in amorphous polylactic acid. The cross polarization buildup curves for methine and methyl functional groups measured at magic angle spinning rates of 4 and 10 kHz, under Hartmann–Hahn conditions determined from corresponding Hartmann–Hahn matching profiles, confirmed the presence of 1H–13C spin pairs isolated from lattice since transient oscillations were observed in the initial stages of buildup curves. The values of dipolar coupling constants derived from Fourier transforms of cross polarization buildup curves indicate the presence of rigid methine groups and two kinds of methyl functional groups which differ in mobility. This could be due to the presence of amorphous phase with chain aggregations and phase with less spatial restrictions in this material. Fitting of theoretical expressions to experimental data provided additional information on the cross polarization process in this material.

The main goal of this study is to develop the new external thermal insulation composite system (ETICS) by integration of flexible photovoltaic (FPV) and encapsulated phase change materials (PCM). This work is the first step of the international project En-ActivETICS and concerns mainly material selection and systems integration issues. The paper presents a complete solution of façade component which integrates thermal insulation, heat storage and electricity generation - En-ActivETICS that combines ETICS technology with a self-supporting flexible photovoltaic elements. This system will be applicable for both masonry or concrete constructions and it is a new step in the development of building facade technology allowing to achieve a component classified to the group of functional material. In the paper, the formulation of basic principles of En-ActivETICS as well as an overview of existing materials and technologies is presented. Finally, the initial concept of the system is described. The main features of that system is using an elastic, high heat capacity and frost resistant adhesive joining flexible PV with thermal insulation.

The mechanical and electrical properties of a styrene-butadiene rubber (SBR) matrix reinforced with carbon black, at various weight fractions were experimentally studied. Τhe electroconductive composites were used for strain sensing, under tension, by measuring together strain and electrical resistance. The storage and loss modulus decrement with strain were also investigated, on the basis of Payne effect, while a micromechanical model developed elsewhere was employed for the interpretation of the reinforcing mechanism of the composites examined.

Single-pulse 13C NMR spectra and spin-lattice relaxation times T1(1H), detected indirectly via 13C carbons, and T1(13C) were measured at 31°C for virgin pelletized and annealed polylactic acid (PLA) samples using the magic-angle spinning technique. The structural relaxation resulting in more regular crystals with narrower conformation distribution and increase in the lamellae thickness and crystallinity brought about by annealing at 100°C was deduced from the narrowing of the 13C NMR lines and proton spin-lattice relaxation times T1(1H). The spin-lattice relaxation times T1(13C) related to the respective carbons of the α-polymorph of PLA are also discussed in the study.

Three different surface modifications of montmorillonite (MMT) have been investigated regarding the modifier effect on the ultimate properties of natural rubber-clay nanocomposites. The reference filler was modified by natrification of the native MMT, and was subsequently modified by two alkylammonium salts to achieve exchange of Na+ with selected organic cations, either octadecyltrimethylammonium (ODTMA) or oleyltrimethylammonium (OLEYL). Consequently, varying concentrations of MMT fillers (1, 3, 5 and 10 phr) were mixed with the elastomeric matrix natural rubber SMR 20 aimed to melt intercalation. For both composites containing organo-modified fillers, vulcanization characteristics revealed an increase of curing rate with rising filler concentrations, while XRD diffraction indicated the formation of intercalated as well as exfoliated structures. The morphology of the natural rubber-clay composites examined by electron microscopy (TEM and SEM) supported the conclusions of the XRD results regarding the intercalation and exfoliation of the surface-modified fillers to smaller nano-size aggregates, particularly tactoids of a few layers or a few thin clay layers. Tensile strength and elongation at break, increased with rising mass content of MMT fillers in the composites. The dependences indicate certain differences in the reinforcement mechanism depending on the surface modifier; while the effect of ODTMA consists in substantial hydrophobization of the surface, it is suggested that OLEYL filler apparently participates also in vulcanization reaction by the double bond in the middle of the aliphatic chain of the ligand.

Crosslinking of virgin polyamide 6 (PA-6) and PA-6 filled with 30 wt% glass fibers (GF) was investigated. The crosslinking was initiated by electron irradiation applying dose ranging from 50 to 500 kGy. The gel point was determined to be 200 kGy for both materials. The results obtained indicate that the GF presence may retard gel formation in the PA-matrix. The irradiation of unfilled PA-6 resulted in an increase in tensile strength at break and Young׳s moduli (a minimum 50% gel content is needed), tensile properties at yield were not affected by crosslinking. Thermal resistance, as measured by the heat deflection temperature and Vicat softening temperature, was affected only marginally. Considering these effects, electron beam irradiation is found to be more beneficial for the virgin PA than for the corresponding PA/GF composite.

Electroconductive composites were prepared using either elastomeric (styrene–butadiene rubber) or thermoplastic (polycaprolactone) matrix with varying amounts of two grades of electroconductive carbon black. For all composites, electrical conductivity was measured during rising deformation and at the same time a stress–strain curve was recorded. The changes in electrical conductivity during deformation were not monotonic, and several extremes were observed. From a comparison of the mechanical and electrical responses of the materials, a decrease in the conductivity was observed at the beginning of deformation in the Hookean elastic region. At a deformation near the yield point for the thermoplastic matrix and near the inflection point for the elastomeric matrix, the increase in conductivity was observed, followed by a decrease in conductivity in the region of plastic flow. All effects of conductivity changes were interpreted in terms of either the destruction or the formation of new conductive pathways formed by the filler. The changes in the structure of reinforcing carbon blacks may be a general process for other filler materials, including nonconductive reinforcing fillers. Thus, electrical conductivity may be correlated with the specific features of the physical network of the reinforcing filler that affect the mechanical properties of the composite.

Polyester foil was treated by the surface diffuse barrier discharge (SDBD) plasma at atmospheric pressure in oxygen and/or in nitrogen containing a small amount of oxygen to improve its surface and adhesive properties. Changes in a chemical structure of the polyester were analyzed by electron spin resonance (ESR) spectroscopy, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and by X-ray photoelectron spectroscopy (XPS). The changes in surface morphology were studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). A surface energy as well as an adhesion of polyester modified by the SDBD plasma to polyacrylate significantly increased. The efficiency of the modification by the SDBD plasma depends on the used processing gas as well as on the modification time. The decrease in the surface energy of polyester modified by the SDBD plasma due to hydrophobic recovery was also investigated. A correlation between adhesive properties of polyester modified by the SDBD plasma and its surface has been found.

This paper reports strong, reversible actuation of nanocomposites on the base of ethylene vinyl acetate (EVA) filled with multiwalled (MWCNTs) and singlewalled carbon nanotubes (SWCNTs). The carbon nanotubes (CNTs) dispersion within the EVA matrix was ensured with pyrene-based compatibilizer and the alignment of the CNTs within a matrix was induced by shear stress to 50% applied as a prerequisite for unilateral photo-actuation. The CNT dispersion within EVA matrix was characterized by transmission electron microscopy (TEM). The dependence of the actuation stress as a function of CNTs concentration, energy and intensity of light was studied. Stress variation of actuation and relaxation were evaluated. The photo-actuation responses showed contraction under illumination up to 170 kPa for EVA-CNTs-based nanocomposites. Repeatability of photo-actuation process up to 100 cycles was observed. High optical-to-mechanical energy conversion factor (ηM) of 55 MPa W−1 for EVA nanocomposite containing 0.1 wt.% MWCNTm during illumination by red light-emitted diode (LED) is reported.

Crosslinking of polyamide 6 (PA) and filled one with glass fibres (PA/GF) was initiated via macroradical formation by gamma irradiation either in air or in inert argon atmosphere. The crosslinked portion was found to start at absorbed dose around 300 kGy and achieved about 60 and 40 wt% for PA and PA/GF, respectively, if irradiation proceeded in inert, while in air molecular weight increase was only observed without crosslinked gel formation. DSC indicated that irradiation leads to a decrease in crystallinity as well as lamellae thickness. Besides crosslinking, scission of polymer chains also occurs. Modest increase of impact strength was found for PA while small decrease for PA/GF was observed. The dependence of Young’s modulus values on the irradiation dose indicates a minimum around gel point being more pronounced for PA compared to the composite. Irradiation resulted in minor changes in tensile strength and elongation at break while a substantial increase in the elongation at yield was found for PA if irradiated in inert atmosphere. Generally, the application of an optimal dose of gamma irradiation in air results in an increase of toughness of PA without changing other mechanical properties.

The paper is aimed on the investigation of natural ageing of plasticized poly(lactic acid)/poly(β-hydroxybutyrate) PLA/PHB blend films during their one-season application as mulches under real field conditions in the western part of Slovakia. Acetyl tributyl citrate (ATBC) was used as the plasticizer. The analysis was performed on three differently exposed parts of the foil: i) buried in soil, ii) exposed to sunlight, and iii) shadowed by plants. In parallel, UV irradiation of the blend under laboratory controlled conditions (constant temperature of 30°C and relative humidity of 55 %) was carried out. The degradation effect was followed by changes in the molar mass, chemical and crystalline structures, as well as in thermal and mechanical properties. The ternary PLA/PHB/ATBC blend lost its tensile properties faster when buried in soil than when exposed to sunlight. This result is in agreement with the data obtained for the UV-irradiated materials. Young’s modulus values showed a significant mechanical degradation under the UV irradiation as well as during natural ageing. The study was also focused on the influence of mulches on the yield and quality of sweet pepper production, characterized by carotenoids and vitamin C content.

Low-density polyethylene (LDPE) modified by atmospheric dielectric surface barrier discharge plasma in oxygen was investigated to improve surface properties and adhesion of LDPE to more polar polymers. The process of plasma modification was investigated using several methods—surface energy measurements, Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The surface energy of LDPE increased significantly after activation by oxygen barrier plasma even at very short time of modification. The FTIR-ATR spectra manifested the presence of carbonyl functional groups on the surface of polymer pre-treated by oxygen barrier plasma. It was shown by SEM, and AFM, that the topography of modified LDPE was significantly changed and the surface of modified polymer exhibited higher roughness in comparison with unmodified polymer. The surface energy of treated LDPE diminished in the course of ageing especially during the first 10 days after modification by barrier plasma. Hydrophilicity of the modified LDPE surface was stabilized by photochemical post-functionalization with 2,2,6,6-tetramethylpiperidin-4-yl-diazoacetate. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Epoxy resins are materials capable of polymerizing under certain conditions, i.e., a temperature and the presence of a hardener, yielding a three-dimensional net formed by the crosslinking of the chains. This polymerization is also called the curing process. During the curing, different physical processes can be detected, namely, formation of polymer chains and their crosslinking. Thermodynamic and transport characteristics change markedly. A new thermal-conductivity sensor was used for monitoring of the curing process. The principle of the sensor is based on the hot-ball method for measuring the thermal conductivity. The sensor recognizes the processes operating during polymerization. This paper deals with the monitoring of the curing process of diglycidylether of bisphenol A (DGBA) epoxy resin modified with aromatic reactive diluent, where the curing rate is controlled by the temperature and boron trifluoride (BTF) hardener. A short description of the measurement method is given.

High-density polyethylene (HDPE) surface was modified by radio-frequency discharge plasma and subsequently grafted by alkoxy silane to form a new surface containing polar functional groups. Reaction of the polar groups with vinyl silanes significantly improved hydrophilicity of the polymer. The decrease of surface energy of polymer modified by plasma in the course of ageing was stabilized by silane grafting. The changes in chemical structure of the polymer were analyzed by ATR-FTIR spectroscopy, surface roughness was studied using AFM. The surface energy, and its polar contribution of plasma modified HDPE increased, as well as peel strengths of adhesive joints to polyacrylate.

The effect of various modifiers on the structure and properties of clay/natural rubber nanocomposites are investigated with the aim to evaluate the effect of size and structure of the modifier. Nanocomposites are prepared by melt intercalation method. Mechanical properties of the cured rubber containing nanoclay are compared with the reference compound without the filler. No improvement of mechanical properties is observed for small organic cations; however, stress and strain at break of clay/rubber nanocomposites increase with rising number of octyl chains in the interlayer spaces of organo-clays. Concerning organo-cations with the same number of carbon atoms, more effective are the modifiers with several shorter carbon chains compared to those with one long chain. The composites exhibit hybrid structure of nanocomposite and microcomposite as revealed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The details of the structure are supported by DMTA and hysteresis measurements. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 3447-3455, 2013

Polyamide-6 (PA-6) irradiated by a 500 kGy electron beam (EB) dose or by 500 and 1000 kGy proton beam (PB) doses was examined by FTIR spectroscopy, crosslinked portion determination, DSC and tensile properties measurements. When using the same dose (500 kGy), the decrease in both melting temperature and crystallinity is similar for both radiation types; however, the EB generates more gel than the PB. According to FTIR spectra, irradiation by PB leads to more extensive structural changes; this result is assigned to the larger proton dimension compared to the electron. The PB results in attacking original crystalline phase, generation of unsaturated structures in ethylene sequences, a splitting of macromolecules into fragments that contain amine groups and terminal methyl moieties unlike the EB where similar effects were not observable. Consequently, PB irradiation results in less pronounced growth of Young modulus and strength as well as higher elongation compared to EB. FTIR analysis of both PA-6 irradiated by the PB applying dose of 1000 kGy and gel isolated from it showed that beside amorphous phase, the gel fraction contains also mixed crystalline phase, however, a small amount of crystalline phase with fully planar conformation is also present. The results indicate that the gel crystalline phase in the gel contains also a new component that originates from shorter macromolecule fragments generated by the PB radiation.

The high-resolution solid-state 13 C NMR spectra were recorded for metallocene (m) and Ziegler-Natta (ZN) iso- tactic polypropylenes (iPP) in pelletized form using cross polarization (CP) and magic angle spinning (MAS) techniques within the temperature range of 20-160°C. Besides the CP MAS experiments also the MAS 13 C NMR spectra (without CP), MAS 1 H NMR spectra and rotating frame spin-lattice relaxation times T1" ( 13 C) were measured at elevated temperatures. With the rise of temperature the splitting of CH2, CH and CH3 signals into two components was detected in 13 C NMR spec- tra and assigned to amorphous and crystalline phases. The temperature dependences of chemical shifts and integral intensi- ties obtained from the deconvoluted spectra provided information on the main chain and CH3 groups motions in amorphous and crystalline regions of studied samples. While T1" ( 13 C) values show that the rate of segmental motion in amorphous regions in m-iPP and ZN-iPP is virtually the same, larger linewidths in 13 C and 1 H NMR spectra indicate somewhat larger restraints of the motion in amorphous regions of ZN-iPP.