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1

The Temperature and Pressure Dependence of the Free Volume in Fluoroelastomers from PALS and PVT Experiments

100%

Dlubek G., Sen Gupta A., Wawryszczuk J., Kilburn D., Pionteck J., Krause-Rehberg R., Goworek T., Alam M., Kaspar H., Lochhaas K.

Acta Physica Polonica A

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2005

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vol. 107

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issue 4

685-689

EN

Positron lifetime and pressure-volume-temperature experiments were performed as function of T (100-485 K) and P (10^{-5} Pa-500 MPa) on a fluoroelastomer. From positron annihilation lifetime spectroscopy, analyzed with LT9.0 assuming a dispersion in the e^+ (τ_2) and o-Ps (τ_3) lifetime, the mean, 〈v_h〉, and the width (standard deviation), σ_h, of the hole size distribution were calculated. The pressure-volume-temperature data were analyzed using the Simha-Somcynsky hole-lattice theory to estimate the specific hole free volume V_f. From a comparison of V_f with 〈v_h〉 the specific hole number, N'_h, is estimated. The data from thermal expansion and pressure experiments show complete agreement when taking into account the compressibility of the occupied volume.

2

Free-Volume and Tensile Properties of Glass Fibre Reinforced Polyamide 6 Composites

100%

Dryzek E., Wróbel M., Juszyńska-Gałązka E.

Acta Physica Polonica A

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2017

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vol. 132

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issue 5

1501-1505

EN

The tensile properties and free volume of commercially available modified polyamid 6 and polyamid 6 composites with 15 and 30 wt% of glass fibre were the subject of the studies. The tensile test allowed us to obtain the stress-strain curves and determine the tensile properties of the polyamid 6 samples. The positron lifetime measurements were performed for the samples before the test and for the samples in the vicinity of the break after they failed. The composites exhibited slightly lower values of the ortho-positronium lifetime and therefore smaller size of the local free volumes in comparison to polyamid 6 without reinforcement. The analysis of the positron lifetime spectra indicated size distribution of the free volume. The initially narrower distributions for the composite samples became broader as a result of the deformation. The deformation caused also increase of the ortho-positronium intensity in the obtained positron lifetime spectra.

3

Positron Annihilation Lifetime Spectroscopy of ABS Objects Manufactured by Fused Deposition Modelling

100%

Dryzek M., Dryzek E.

Acta Physica Polonica A

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2017

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vol. 132

|

issue 5

1506-1508

EN

Positron annihilation lifetime spectroscopy was used to study acrylonitrile butadiene styrene (ABS) specimens manufactured using fused deposition modelling to explore possibilities of identifying differences in molecular structure. The set of specimens was prepared including square tiles and long rectangular tiles (100 mm and 200 mm long) with all filament roads parallel to the longer edge. All types of tiles were produced with various infill line distance parameter resulting in different overlapping of the roads in horizontal and vertical directions. The slight increase of the ortho-positronium lifetime indicating increase of the mean free volume radius was observed for the longest tiles for which influence of weld interface is expected to be most pronounced. No differences were observed for different infill line distance parameters.

4

A Novel Method for Manufacturing Polymer/Metal Hybrid Structures

100%

Altan M., Yavuz B.

Acta Physica Polonica A

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2016

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vol. 129

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issue 4

639-641

EN

In this study, a method for manufacturing polymer/metal hybrid structure is presented in which traditional plastic injection machine was converted to plastic injection forming (PIF). In this method, deforming of the metal and adhering the metal to the polymer is done in one step. In the experimental study, a special mold within rectangular cavity was used during PIF process. Aluminum plates of different thicknesses were used as the metal parts of the structure. The injected polymers were pure polystyrene and elastomer-added polystyrene. The deformability of the Al plates was examined under different injection pressures. In order to provide adhesion between metal and polymer, an adhesive of elastomeric nature was applied on the metal plate prior to injection molding. Bending test was applied to determine the flexural strength and maximum deflection of the polymer/metal hybrid structures. The obtained results were satisfactorily acceptable in improving the method for designing and manufacturing polymer/metal hybrid structures in one step.

5

A Simplified Method for the Estimation of Hole Free Volume Fraction from the Specific Volume

100%

Dlubek G., Pionteck J.

Acta Physica Polonica A

|

2008

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vol. 113

|

issue 5

1331-1338

EN

A brief introduction in the equation of state of the Simha-Somcynsky hole theory is presented. This theory allows to calculate the volume fraction h of free volume holes from pressure-volume-temperature experiments. These holes are detected by ortho-positronium and from the value of h and the mean ortho-positronium hole size the hole density may be calculated. We discuss a simplified method to estimate h which makes use of the relation V* = 1.52V_W between the scaling volume V* of the Simha-Somcynsky hole theory equation of state and the van der Waals volume V_W. Moreover, we present a new simplified method for the estimation of h which starts with the Schottky (Arrhenius) equation for the concentration of thermal vacancies and makes use of a linear relation between the scaling temperature T* and the hole formation enthalpy H_h, H_h(kJ/mol)=6.54×10^{-4}T*(K).

6

Homonuclear Separated Local-Field Spectroscopy by Magnetization-Exchange NMR

100%

Demco D. E., Filip X., Filip C., Chira D., Cozar O.

Acta Physica Polonica A

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1997

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vol. 92

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issue 6

1135-1149

EN

The possibility to perform homonuclear separated-local field NMR spectroscopy by magnetization-exchange is presented. Solid-state one-dimensional proton magnetization-exchange NMR is used to investigate intergroup residual dipolar couplings in cis-1,4-polybutadiene elastomer. A three-spin model is employed, in which the CH- and CH_{2}-protons are considered to be coupled by residual dipolar interactions. The magnetization-exchange process between the CH- and the CH_{2}-group in the regime of short mixing time provides valuable insight regarding molecular order. The spin-system response reflects well-localized dipolar interactions. The residual intergroup dipolar couplings are measured along the average polymer-chain direction for different temperatures. The dynamic order parameter along the chains is also evaluated.

7

The Role of Ferric(III) Oxide in Poly-(1,4-Phenylene Sulphide) Curing. EPR and X-ray Studies

100%

Wejchan-Judek M., Hoffmann S., Goslar J., Garbarczyk J.

Acta Physica Polonica A

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2005

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vol. 108

|

issue 1

107-112

EN

Commercially available poly-(1,4-phenylene sulfide) = PPS with trade names TEDUR and RYTON contain a great amount of Fe(III) (order of 10^{20} Fe/gram) as shown by electron spin resonance spectra. The curing of the pure and Fe-doped (0.2% Fe_2O_3) PPS polymers proves that Fe(III) can be used for improvement of the PPS strength by increasing the polymer cross-linking and a decrease in the polymer crystallinity degree as shown by X-ray diffraction.

8

Investigation of the Crash Boxes Light Weighting with Syntactic Foams by the Finite Element Analysis

80%

Özer H., Can Y., Yazıcı M.

Acta Physica Polonica A

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2017

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vol. 132

|

issue 3

734-737

EN

Light-weighting is a new scope in the automotive industry to accommodate new emission regulations. The parts produced with conventional metallic materials are replaced with parts produced by using light weight or high strength materials, to obtain light weighted equivalents of the same strength. Foam core sandwich structures, high strength steels, composite materials are the most used alternative materials. Syntactic foams that show outstanding performance in case of high-speed collisions have an excellent utility as energy absorbers in vehicle crash boxes. Syntactic foams are modeled in crash boxes at various filling rates and filling patterns in the context of this study. As results of the FEM analyses, it is observed that syntactic foams have excellent crash performance, as well as weight-reducing effect in vehicle crash boxes.

9

Estimation of the Degree of Crystallinity of Partially Crystalline Polypropylenes Using ^{13}C NMR

80%

Hronský V., Koval'aková M., Vrábel P., Uhrínová M., Olčák D.

Acta Physica Polonica A

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2014

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vol. 126

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issue 1

409-410

EN

The paper deals with a method for the estimation of the degree of crystallinity for partially-crystalline isotactic-polypropylenes (i-PP) using high-resolution solid-state ^{13}C NMR. For this purpose direct polarization ^{13}C MAS NMR spectra were measured for i-PP samples with different degrees of crystallinity at 98°C. The areas beneath the resonance lines in these spectra correspond to the number of carbons in particular functional groups, while the widths and shapes of the lines reflect the degree of crystallinity, crystalline modifications, distribution of chain conformations and the chain mobility. The ^{13}C MAS NMR spectra, measured using appropriate combination of delay time and high proton decoupling field, made it possible to detect only amorphous domains in the sample. This enabled identification of the lines associated with the amorphous domains in the complete ^{13}C MAS NMR spectra and provided sufficient information for reliable estimation of the degree of crystallinity. The heteronuclear Overhauser enhancement of the ^{13}C NMR signals due to short delay time was taken into account in our calculations.

10

Positron Lifetime in Hostaphan

80%

Kostrzewa M., Bujnarowski G., Kluza A., Szuszkiewicz M.

Acta Physica Polonica A

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2006

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vol. 110

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issue 5

615-620

EN

Positron lifetime measurements in hostaphan RNK, used for encapsulation of ^{22}Na positron sources, were performed. It was found that the parameter of positron lifetime spectra in hostaphan RNK differ markedly from those for other forms of polyethylene terephthalate. The maximum penetration depth of positrons from RNK hostaphan amounts 0.42 mm. The information gained in the present study is of great importance for experimenters using hostaphan RNK for encapsulation of positron sources.

11

Magnetic Properties of Conducting Polymers

80%

Aksimentyeva O., Artym V., Melnik O., Plusnina T.

Acta Physica Polonica A

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1994

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vol. 85

|

issue 1

237-240

EN

Magnetic susceptibility, electroconductivity and structure of polymer conducting layers of polyaniline and polyaminophenoles were studied in a wide temperature range. It was found that magnetic susceptibility depends on the doping level of polymer and the nature of doping agents. The obtained result suggested the existence of metallic states in highly doped conducting polymers.

12

Electron Spin-Lattice Relaxation in Polymers and Crystals Related to Disorder and Structure Defects

80%

Hoffmann S., Hilczer W., Radczyk T., Polus I.

Acta Physica Polonica A

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2003

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vol. 103

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issue 4

373-385

EN

Temperature dependences (4-300 K) of the electron spin-lattice relaxation have been determined by electron spin echo technique for free radicals in two polymeric systems: phenol-formaldehyde resin and polyhydrazodisulphide. The dependences are described in terms of dynamics specific for amorphous systems involving two-level tunnelling states at low temperatures, exchange-coupled clusters of paramagnetic centres and local oscillators. Some universal temperature behaviour of the spin-lattice relaxation of amorphous systems is suggested, with a strong increase in relaxation rate with temperature at low temperatures and much weaker increase above 50 K with characteristic linear temperature dependence in a broad temperature range and cosech(Δ/kT) -type behaviour. It is also shown that the amorphous-type behaviour appears in low temperatures relaxation studies of single crystals but it is due to a non-uniform distribution of doped paramagnetic ions. Such behaviour we have found in Tutton salt crystals doped with Cu^{2+}, as well as for free radical centres produced by ionising irradiation in (NH_4)_3H(SeO_4)_2 and Li(N_2H_5)SO_4 single crystals, where extended phonons are suppressed around radiation damage centres suggesting a local amorphisation of the crystal structure.

13

A Novel High Strain Rate Sensitive Rigid Polyurethane Resin Based Syntactic Foam

80%

Yazıcı M.

Acta Physica Polonica A

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2016

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vol. 129

|

issue 4

613-616

EN

Syntactic foams are closed cell structured foam materials and present improved properties for lightweight and high performance material requests. They have been widely used in naval, aeronautical, aerospace, civil, industrial, and automotive engineering applications on account of their good acoustical attenuation, excellent strength to weight ratio, vibration isolation, dielectric properties. In this study, a novel high strain rate sensitive syntactic foam was developed. A rigid polyurethane resin was used as a binder material. Glass bubbles were used as an additive for producing cell structure. Elastomeric silicone rubber resin were used to change elastic properties of the foam as an additional binder material. Quasistatic compression properties and high strain rate compression properties were obtained by using Instron Universal Tensile-Compression Machine and Split Hopkinson Pressure Bar experimental setup respectively. The results show that developed foams are low dense and very high strain rate sensitive materials. Consequently, developed foam can be used for the blast, impact or ballistic mitigation purpose as a coating material.

14

Correlations between Positron Annihilation Parameters and Macroscopic Properties in Copolymers Belonging to Elastomers Group

80%

Krzemień K., Kansy J.

Acta Physica Polonica A

|

2008

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vol. 113

|

issue 5

1435-1440

EN

The positron annihilation lifetime spectroscopy was used to study correlations between positron annihilation parameters and macroscopic properties in two kinds of polymers from elastomers group. Two kinds of material were investigated: three samples of ethylene octane copolymers (commercial name engage) of different densities and six samples of polybutylene terephtalate-polyether glycol copolymers (hytrel) having different densities. A correlation between intensity of ortho-positronium component and the density (d) of samples was observed for both kinds of material. From the ortho-positronium pick-off lifetime the mean radii (R) of free volume centers were determined. A good linear correlation between R and d was found.

15

Effects of Terpolymer Addition on the Thermal and Termomechanical Properties of Poly(Phenylene Sulfide)

80%

Cetin B., Sahin A., Yilmaz T., Sinmazcelik T., Curgul I.

Acta Physica Polonica A

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2017

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vol. 131

|

issue 3

598-600

EN

Poly(phenylene sulfide) (PPS) is one of the high-performance engineering polymers and it exhibits superior behavior, such as electrical insulation, dimensional and thermal stability, chemical resistance for various industrial applications. In addition to this, PPS has a high degree of crystallinity and it maintains these properties at high temperatures. These advantageous properties of PPS can be dependent on its chemical structure, composed of phenyl groups linked by a sulfur atom, which gives rigidity to the polymer chains. Owing to these properties, PPS is widely used in electrical and electronic components, automobile industry and mechanical applications. On the other hand, brittleness of PPS restricts its further applications. For this reason, ethylene-acrylic ester-glycidyl methacrylate terpolymer (Lotader®-AX8900) was used to overcome the brittleness of PPS. The effects of terpolymer addition on the thermal and thermomechanical properties of blends were investigated in this study. PPS/Lotader (0, 2, 5, 10 wt.% Lotader®) blends of various compositions were prepared. The blends were prepared by using laboratory scale micro compounder and injection molding machine. Thermomechanical and thermal properties of blends were investigated by means of dynamic mechanic analysis and differential scanning calorimeter test methods. As a result of this study, it was found that increasing loading level of Lotader® significantly decreased the crystallinity and increased glass transition temperature of PPS. On the other hand, Lotader® addition did not affect the melting temperature of PPS considerably. Results of dynamic mechanic analysis test revealed that while damping factor peak and loss modulus values of blends increased with the addition of Lotader®, storage modulus of blends decreased with the increasing loading level of Lotader®. When all test results are considered, it can be concluded that Lotader addition changes the brittle nature of PPS to ductile nature. In addition to this, 2 wt.% Lotader addition to PPS enables the optimum ductility for PPS without deteriorating its other properties.

16

Free-Volume Studies in Polycaprolactone/Poly(propylene oxide) Urethane/Urea Membranes by Positron Lifetime Spectroscopy

80%

Ferreira Marques M., Gordo P., de Lima A., Queiroz D., Norberta de Pinho M., Major P., Kajcsos Z.

Acta Physica Polonica A

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2008

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vol. 113

|

issue 5

1359-1364

EN

Positron annihilation lifetime spectroscopy was used to study the free volume parameters in polypropylene oxide-based tri-isocyanate terminated prepolymer/polycaprolactone diol bi-soft urethane/urea membranes (PU/PCL) with PCL content from 5 up to 25 wt%. Positron annihilation lifetime spectroscopy measurements carried out in the temperature range 298-324 K mirrored the phase separation of the various soft and hard segments present in the membranes. The size and amount of free volume holes determined by positron annihilation lifetime spectroscopy appear to be correlated with the CO_2 gas permeability through the membranes.

17

Dielectric Relaxation in Cellulose and its Derivatives

80%

Rachocki A., Markiewicz E., Tritt-Goc J.

Acta Physica Polonica A

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2005

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vol. 108

|

issue 1

137-145

EN

The relaxation processes in cellulose, methyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose were studied by dielectric spectroscopy. The dielectric spectra for these polysaccharides were measured in the frequency range from 100 Hz to 1 MHz and in the temperature range from 100 to 450 K. The dielectric relaxation data for cellulose, methyl cellulose, hydroxypropylmethyl cellulose were described by Arrhenius and Eyring equations and interpreted as due to a local motion of chain segments via the glucosidic linkages, so-calledβ-relaxation. The same relaxation process was also determined for the hydroxypropyl cellulose polymer in the temperature range of 240-270 K. At higher temperature in hydroxypropyl cellulose another relaxation mechanism occurs due to the reorientation of the side chain built of a few hydroxypropylene groups. The activation parameters of the observed dielectric relaxation processes were determined.

18

Positron Annihilation Lifetime in situ Study of Deformed Polyolefin Elastomers

80%

Krzemień K., Kansy J., Frąckowiak J.

Acta Physica Polonica A

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2005

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vol. 107

|

issue 5

837-841

EN

The positron annihilation lifetime spectroscopy was used to investigate the free volume hole size of ethylene octane copolymers as a function of deformation in the range from 0 to 110% in steps of 10%. For each degree of deformation a series of 5-6 positron annihilation lifetime spectra was collected in situ. All spectra of a given series were analysed simultaneously. They were resolved into three exponential components, of lifetimes parametersτ_i and intensities I_i. The variations ofτ_3 reflect three deformation regions, the elastic range, strain softening range, and plastic region.

19

Molecular Dynamics Simulations of Poly(dimethylsiloxane) Properties

80%

Fojtíková J., Kalvoda L., Sedlák P.

Acta Physica Polonica A

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2015

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vol. 128

|

issue 4

637-639

EN

Models of poly(dimethylsiloxane) (PDMS) oligomers differing in topology are defined and structure and mechanical properties of these analysed by three different theoretical approaches: the Bicerano graph method, atomistic molecular dynamics simulations and mesoscale dissipative particle dynamics. The calculations are performed within the simulation software environment Materials Studio (Accelrys Software Inc.). The obtained values of the Young and bulk modulus are juxtaposed to experimental data available for real PDMS materials and quality of the agreement discussed in relation to the theory level and simulation method applied.

20

Outdoor Ageing of an Ethylene-Propylene Copolymer: A Positron Annihilation Study

80%

Consolati G., Quasso F., Gallo R., Severini F.

Acta Physica Polonica A

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2005

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vol. 107

|

issue 5

805-810

EN

An investigation on the environmental degradation of an ethylene-propylene copolymer was carried out through positron annihilation lifetime spectroscopy, density and differential scanning calorimetry measurements. Polymer sheets were exposed to sunlight up to 11000 hours. Density and melting enthalpy increase with ageing, while ortho-positronium intensity decreases; ortho-positronium lifetime does not show significant variations up to 4400 hours. At higher exposures it starts to decrease. Outdoor ageing produces an increased crystallinity of the copolymer; also a degradation occurs with formation of carbonyl groups. The corresponding Ps inhibition is the main reason for the decrease in ortho-positronium intensity, the other one being the reduced amount of the amorphous phase available. The lifetime decrease observed at the highest exposures can be interpreted in terms of a shrinking of the nanoholes trapping positronium.

Refine search results

The Temperature and Pressure Dependence of the Free Volume in Fluoroelastomers from PALS and PVT Experiments

Free-Volume and Tensile Properties of Glass Fibre Reinforced Polyamide 6 Composites

Positron Annihilation Lifetime Spectroscopy of ABS Objects Manufactured by Fused Deposition Modelling

A Novel Method for Manufacturing Polymer/Metal Hybrid Structures

A Simplified Method for the Estimation of Hole Free Volume Fraction from the Specific Volume

Homonuclear Separated Local-Field Spectroscopy by Magnetization-Exchange NMR

The Role of Ferric(III) Oxide in Poly-(1,4-Phenylene Sulphide) Curing. EPR and X-ray Studies

Investigation of the Crash Boxes Light Weighting with Syntactic Foams by the Finite Element Analysis

Estimation of the Degree of Crystallinity of Partially Crystalline Polypropylenes Using ^{13}C NMR

Positron Lifetime in Hostaphan

Magnetic Properties of Conducting Polymers

Electron Spin-Lattice Relaxation in Polymers and Crystals Related to Disorder and Structure Defects

A Novel High Strain Rate Sensitive Rigid Polyurethane Resin Based Syntactic Foam

Correlations between Positron Annihilation Parameters and Macroscopic Properties in Copolymers Belonging to Elastomers Group

Effects of Terpolymer Addition on the Thermal and Termomechanical Properties of Poly(Phenylene Sulfide)

Free-Volume Studies in Polycaprolactone/Poly(propylene oxide) Urethane/Urea Membranes by Positron Lifetime Spectroscopy

Dielectric Relaxation in Cellulose and its Derivatives

Positron Annihilation Lifetime in situ Study of Deformed Polyolefin Elastomers

Molecular Dynamics Simulations of Poly(dimethylsiloxane) Properties

Outdoor Ageing of an Ethylene-Propylene Copolymer: A Positron Annihilation Study