Dynamic mechanical behavior of polymer modified bitumen

The dynamic mechanical behaviour of bitumen (BIT) modified with styrene/butadiene/styrene block copolymer (SBS) were investigated. Dynamic mechanical analysis (DMA) were performed in the temperature range –80 to 60 °C. The primary viscoelastic functions were determined at the traffic frequency, 5 Hz. The BIT+SBS blends were investigated in creep fatigue regime at temperature 10, 20, 30, 40 and 50 °C. Dynamic mechanical behaviour of BIT+SBS blends depends on their morphological characteristics, number of phases, phase compositions and phase content in blend, as well as time and temperature. The curves of primary viscoelastic functions, storage modulus (E′), loss modulus (E′′) and loss tangent (tg δ) vs. temperature of polymer modified bitumen differ from unmodified bitumen and indicate the presence of the swollen polybutadiene and polystyrene phases in bitumen phase. The curve E′ vs. temperature of polymer modified bitumen show the rubbery plateau. With the increment of SBS content the rubbery plateau is shifted to high temperatures. At the constant load the creep values of BIT-SBS blends increase and those of creep modulus decrease over a period of time. These effect are more pronounced in samples with higer content of SBS. The time-temperature correspondence principle was applied to create master curves for the reference temperature 10 °C for the creep modulus of BIT + SBS blends. The data were analysed using WLF and Arrhenius equations. Electronic Publication     

Engineering characterization of recycled asphalt concrete and aged bitumen mixed recycling agent

A recycling agent is commonly used to restore the aged bitumen to a condition that resembles that of the virgin bitumen. Three reclaimed asphalt pavement (RAP) stockpiles were sampled, and the aged binders recovered from RAP binders were mixed with recycling agents at ten levels to produce bitumen blends. The blends using virgin bitumen as the softening agent exhibited a significantly different rheological behavior from ones using the rejuvenating agent. The addition of a recycling agent could shift up or down the master curve of the blend vertically, depending on the engineering properties of the recycling agent. A normalized viscosity ratio (NVR) model was used to characterize the rheological properties of aged bitumen mixed with softening and rejuvenating agents. An interaction parameter was introduced into the model to consider the physico-chemical reaction between aged bitumen and recycling agent. This mixing rule was compared to the method specified in the blending chart by the Asphalt Institute (AI). The blending chart was shown to be applicable to determine the amount of the softening agent required to meet the target viscosity. The NVR model appeared to be a better tool for the rejuvenating agent to predict the viscosity of a recovered bitumen blend than the AI chart.     

Thermal and mechanical properties of EPDM/PP + thermal shock-resistant ceramic composites

Dynamic vulcanizate blends of polypropylene (PP) and ethylene–propylene-diene rubber (EPDM) were filled with 5 wt% of micro-scale ceramic powder. To overcome the difficulty of particles dispersion and adhesion, the filler was modified through grafting using three kinds of organic molecules. A combination of Raman data with thermogravimetric analysis (TGA) results prove that grafting of organic macromolecules onto ceramic surfaces takes place. Dynamic mechanical analysis (DMA) has been performed from −100 to +50 °C; addition of the ceramic increases the storage modulus E′, more so for modified filler. Compared to PP and thermoplastic vulcanizate (TPV), a higher thermal expansion is seen after addition of the ceramic filler, a result of creation of more free volume. The tensile modulus of the composites is about 1.2 times that of pure TPV, an increase in the rigidity clearly caused by the ceramic. Fracture surfaces show weak bonding of filler particles to the matrix. In the sample containing modified filler the tensile deformation is going through the polymer matrix. The brittleness, B, decreases upon surface modification of the ceramic. The highest value of B is seen for the PP + unmodified ceramic while lower B values are obtained for TPV and its composites.     

Structural characteristics of peat bitumen and peat/petroleum bitumen blends,and consideration of their potential use as road binder materials

Bitumen derived from peat was blended with petroleum bitumen and subjected to laboratory evaluation for use as road binder material. Standard empirical procedures used included penetration, softening point and Fraass brittle point determinations. Rheological behaviour has been assessed at low shear rate using a sliding plate microviscometer and at high shear rate using a cone and plate instrument. Thermal analysis techniques including calorimetry and dielectric thermal analysis have been used to obtain fundamental structural information. Properties have also been measured after accelerated ageing. Peat bitumen is shown to differ significantly from petroleum bitumen in having a relatively high (30%) crystal content; however, as crystal melting commences below 20 ° C, the initial effect obtained in blending with petroleum bitumen is that of a plasticizer, reducing blend viscosity and increasing penetration. Crystallinity in the blends is lower than expected and this is ascribed to diffusional control of the crystallization process. Peat bitumens show a marked propensity to harden on heating, presumably due to condensation reactions increasing molecular weight, and this more than compensates for the plasticizing effect. The results suggest that age hardening will limit technically useful blends to a maximum of 17% wt/wt peat bitumen.     

Analysis of dipolar relaxation in polyurethane/polyaniline blend

Thin films of blend made up of castor oil-based polyurethane (PU) and polyaniline (PANI) were obtained by casting. The molecular mobility was studied using dielectric spectroscopy and thermally stimulated depolarization current (TSDC) for blends with two different compositions (90/10, 80/20) and the results were compared with PU pure. The peak located around −60°C in TSDC thermograms of PU/PANI blend has dipolar behavior and might be attributed to the change in the molecular chain due to the interaction between isocyanate and the solvent. Vogel-Fulcher Tammann fits was performed on the observed relaxation and the result shows a α-relaxation-like.     

Determination of polymer content in modified bitumen

Polymer-modified bitumen (PMB) has been increasingly used to enhance pavement performance. Two styrenebutadiene-styrene (SBS) copolymers were mixed with two bitumens by weight of the blend. This paper aims at developing the procedure to determine the proper polymer content to be mixed with bitumen. Tests including storage stability test, dynamic shear rheometer and scanning electron microscopy (SEM) were conducted to investigate the viscoelastic properties and microstructures of PMB. The addition of polymers increased the viscosity, softening point, toughness and complex modulus of bitumens. SEM results indicated that, as the polymer content increased, SBS gradually became the dominant phase that resulted in an increase in PMB's mechanic properties. Good compatibility produced an elastic network into the PMB up to 6% polymer concentration. The optimum polymer content was determined based on the rheological properties and the formation of the critical network. Adding higher polymer contents could lead to the separation of polymer and bitumen. The softening point temperature difference between top and bottom samples should be controlled within 2°C to monitor PMB's stability.     

Effect of core–shell structured modifier ACR on ASA/SAN/ACR ternary blends

In this study, acrylonitrile–styrene–acrylic terpolymer/styrene–acrylonitrile copolymer/acrylic resin (ASA/SAN/ACR) ternary blends with different compositions were prepared by melting blending. Properties of the ternary blends were studied by differential scanning calorimetry, heat distortion temperature (HDT), Fourier transform infrared (FTIR) spectra, melt flow rate (MFR), mechanical properties, and scanning electron microscopy (SEM). The blends showed two T _gs at about −48 and 109 °C. FTIR analyses showed no strong interactions between the characteristic groups existed in the prepared blends. No obvious phase separation observed in SEM images indicated good compatibility in the blend system. With respect to mechanical properties and processability, the addition of ACR not only led to the improvement of impact strength and elongation at break, but also the decline of tensile strength, flexural properties, hardness, and MFR. Furthermore, heat resistance of ASA/SAN (70/30) binary blends decreased with the addition of ACR, but the HDT of ASA/SAN (30/70) almost remain unchanged.     

Transport properties of high-density polyethylene/ethylene propylene diene terpolymer blends

Polymer blends based on high-density polyethylene and ethylene propylene diene terpolymer rubber (EPDM) were prepared. The sorption and diffusion of four aliphatic hydrocarbons through the blends were studied in the temperature range of 28–58 °C. Sulfur, dicumyl peroxide (DCP), and a mixture of sulfur and DCP (mixed) were used as cross-linking agents for the blends. Of the three systems, the peroxide vulcanized blends were found to exhibit the lowest penetrant uptake. This has been explained based on the higher rigidity of the –C–C– networks than the polysulfide linkages. The aliphatic liquid penetration through the matrix increased with increase in the EPDM content in the blend. The experimental observations were correlated with the morphology of the blends. Diffusion and permeation coefficients were calculated from the sorption data. A slight deviation from the Fickian trend was observed for the mechanism of transport with an increase in EPDM in the blends. The molar mass between cross-links and thermodynamic parameters of sorption was determined from the swelling data. The experimental observations were compared with various theoretical models.     

Effects of SiO<Subscript>2</Subscript> and TiO<Subscript>2</Subscript> fillers on thermal and dielectric properties of eco-friendly bismuth glass microcomposites of plasma display panels

The effects of SiO₂ (amorphous) and TiO₂ (crystalline, rutile) fillers on softening point (T _s), glass transition temperature (T _g), coefficient of thermal expansion (CTE), and dielectric constant (ɛ) of zinc bismuth borate, ZnO-Bi₂O₃-B₂O₃ (ZBIB) glass microcomposites have been investigated with a view to its use as the white back (rear glass dielectric layer) of plasma display panels (PDPs). The experimentally measured properties have also been compared with those of theoretically predicted values. Both the experimental and theoretical trends of these properties with added filler contents correlate very well. The interaction of fillers with glass which occurred during sintering at 560°C has also been monitored by XRD and FTIR spectroscopic analyses. The microstructures and distribution of fillers in the glass matrix have been analyzed by SEM images. It is observed that the fillers have partially dissolved in the glass at the firing temperature leaving some unreacted filler as residue which results in ceramic-glass microcomposites. In consideration of the desired properties of white back of PDPs, the addition of TiO₂ filler to ZBIB glass is found to be more preferable than SiO₂ filler. The addition of 10 wt% TiO₂ filler yielded T _s, T _g, CTE and ɛ values of 560°C, 480°C, 82 × 10⁻⁷/K and 14·6 which are found to meet the desired values of <580°C, <500°C, <83 × 10⁻⁷/K and <15, respectively with respect to use of PD200 glass as substrate in PDP technology.     

Master curve of filler localization in rubber blends at an equilibrium state

In this study, the phase-specific localization of filler in NBR/NR blends was characterized by means of the selective extraction method and wetting concept. A strong dependence of silica localization on the filler loading was found. A model based on thermodynamic data was proposed for a quantitative prediction of filler localization in rubber blends. The filler localization can be described by a master curve demonstrating a characteristic behavior in dependence on the filler surface tension data of blend components and filler. The effect of filler loading on the silica localization is sufficiently explained by this model by taking into consideration the deactivation of the silanol groups on the silica surface by adsorbed curing additives. Using the master curve, the surface tension of filler affected by curing additives and silane addition can be estimated that may be useful for evaluation and comparison of the effect of different coupling agents. Surface tension values of different fillers were estimated by means of the master curve and they lie in the same order compared to those reported in literature. A potential transfer of filler within a rubber blend can be also quantitatively predicted.     

Nanocrystalline filler induced changes in electrical and stability properties of a polymer nanocomposite electrolyte based on amorphous matrix

An ion conducting polymer nanocomposite electrolyte (PNCE) series of film based on an amorphous polymer host (PMMA)–lithium salt (LiClO₄) complex dispersed with nanocrystalline yttria stabilized zirconia (n-YSZ) is reported. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis have confirmed feasibility of interaction among composite components (i.e. polymer–ion–filler). Ions in the PNCE matrix are present in the form of both free cations/anions as well as contact ion pairs and their concentration depends on filler loading in the matrix. Electrical conductivity enhancement on n-YSZ dispersion occurs by ~2 orders of magnitude at 30 °C and by ~5 orders of magnitude at 100 °C when compared with room temperature conductivity of the undispersed polymer salt (PS) film. The highest achieved conductivity value is ~1.3 × 10⁻⁴ S cm⁻¹ at 100 °C for 2 wt% n-YSZ. An excellent correlation between variation of d.c. conductivity and free mobile charge carriers versus filler loading has been observed. This correlation has been attributed to filler-induced polymer–ion–filler interaction. These evidences have formed the basis to propose a mechanism for ion transport.     

Effect of crystallinity on the mechanical properties of starch/synthetic polymer blends

Crystallization behaviour of starch and maleated blends was studied at 50°C over a period of 20 weeks using wide angle X-ray diffraction (WAXS). The variation of mechanical properties (tensile and flexural) and stress relaxation behaviour of the blends stored at 50°C and −10°C were studied over the same period. The starch content in the blends was 70% by weight. The synthetic polyolefins used in the blends were two grades of ethylene-co-vinyl acetates (EVA) containing 28% and 18% VA, two grades linear low-density polyethylene (melt index of 40 and 20) and high density polyethylene. An increase in the tensile properties of all the blends was observed in the first 5 weeks for samples kept at both temperature conditions. Blend samples kept at 50°C had higher tensile strengths than the ones at −10°C. Flexural strength remained constant over the duration of time. Freshly moulded specimens relaxed faster than the samples aged at either temperature. X-ray diffraction patterns showed that the starch was completely melted and had lost its crystallinity. Also, starch blends with EVA did not show any crystalline structure. The crystallinity in the starch blends with polyethylene was mainly due to the crystallinity of the synthetic polymer. The X-ray patterns of pure synthetic polymers were not found to be different from their functionalized counterparts. Crystal intensity was found to decrease for all the polyethylene blends. The effect of crystallinity on the mechanical properties is discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

CAP-PCL共混合金的结构与性能

采用溶液共混的方法制备了一系列聚己内酯(PCL)与醋酸丙酸纤维素(CAP)的共混薄膜。DMA显示共混物中二者的玻璃化转变温度互相靠近,表明二者之间有一定的相容性。X射线衍射表明,CAP对PCL的结晶有一定的抑制作用,但对其特征晶体结构并无改变。透射电镜下可发现共混物中CAP的相区尺寸减小,形态及排列均未受影响。热重分析表明PCL的加入改善了混合物的热解稳定性。拉伸试验说明与PCL的共混可以在不过多降低拉伸强度的情况下大幅提高断裂伸长率。     

Miscibility and melting properties of poly(ethylene 2,6-naphthalate)/poly(trimethylene terephthalate) blends

The miscibility and melting properties of binary crystalline blends of poly(ethylene 2,6-naphthalate)/poly(trimethylene terephthalate) (PEN/PTT) have been investigated with differential scanning calorimetry (DSC). The glass transition and cold crystallization behaviors indicated that in PEN/PTT blends, there are two different amorphous phases and the PEN/PTT blends are immiscible in the amorphous state. The polymer–polymer interaction parameter, , calculated from equilibrium melting temperature depression of the PEN component was −1.791 × 10⁻⁵ (300 °C), revealing miscibility of PEN/PTT blends in the melt state.     

聚氨酯/纳米复合涂料的红外特性及其力学性能的研究

系统研究了聚氨酯涂料在红外特性及其力学性能。选用三种填料（纳米级氢氧化镁、氧化铬、ITO）对聚氨酯进行共混改性，并讨论了不同含量的填料与性能的关系。含有纳米级层状氢氧化镁的聚氨酯涂料具有最低的红外发射率和最高的红外吸收率。该体系的拉伸强度、断裂伸长率和回弹性相对于纯的聚氨酯体系下降幅度最小，并且涂层耐擦洗次数最高；加入填料后，体系的硬度增加，但用量超过20％后硬度增加不明显；此外，体系的吸水性随填料的增加而显著增加，但用量超过10％，吸水率则开始下降。     

Quantitative mapping of surface elastic moduli in silica-reinforced rubbers and rubber blends across the length scales by AFM

The surface elastic moduli of silica-reinforced rubbers and rubber blends were investigated by atomic force microscopy (AFM)-based HarmoniX material mapping. Styrene–butadiene rubbers (SBR) and ethylene–propylene–diene rubbers (EPDM) and SBR/EPDM rubber blends with varying concentrations of silica nanoparticles (0, 5, 10, 20, 50 parts per hundred rubber, phr) were prepared to investigate the effect of different composition on the resulting morphology, filler distribution and elastic moduli of a specific rubber or rubber blend sample. For SBR, the elastic modulus values varied from 0.5 MPa for unfilled SBR to 5 MPa for 50 phr reinforced SBR with the increase in the concentration of filler. For EPDM, the corresponding values increased from 1.4 MPa for unfilled EPDM to 4.5 MPa for 50 phr reinforced EPDM. Local stiff and soft domains in silica-reinforced SBR and EPDM rubbers and rubber blends were identified by HarmoniX AFM imaging. While the stiff silica particles show modulus values as high as 2 GPa, the rubber matrix reveals modulus values in the range of ca. 30 MPa for the rubber blends to ca. 300 MPa for the unfilled rubbers. The lower value of elastic modulus of the EPDM phase in the blend, compared to the blank EPDM compound can be attributed to the presence of Sunpar oil in the compound which has a very good affinity with EPDM and decreases the rubber modulus. The elastic moduli maps revealed an increase of the areal fraction of silica particles showing an intrinsic surface modulus value with rising silica content in the compound preparation mixture. HarmoniX AFM measurements revealed the formation of larger silica aggregates in EPDM in contrast to SBR where isolated silica particles were observed. For silica-reinforced rubber blends a phase separation into a soft (ca. 40 MPa) and a significantly harder phase could be observed (ca. 500 MPa–1.5 GPa) indicating the incorporation of silica particles in the SBR phase. Using HarmoniX AFM imaging significantly higher surface elastic moduli were observed compared to those obtained by bulk tensile testing. Possible reasons for the observed differences between bulk modulus values and those measured by AFM are discussed in detail, including the aspect of different averaging procedures like inherent to surface probing by AFM versus bulk tensile testing, different filler distributions in SBR and EPDM and the AFM modulus calibration procedures.     

Softening of Bond Stretching Phonon Mode in Ba1?xKxBiO3 Superconductor

Single crystals of Ba_1−x K _x BiO₃ compound for different values of x (0≤x≤0.6) from insulator to superconducting region have been grown by electrochemical method. The crystals have been characterized by powder X-ray diffraction and Laue X-ray to determine the crystal structure, phases and potassium concentration. The phonon dispersion of the crystals in (100) direction has been investigated by high-resolution inelastic X-ray scattering. The phonon dispersion for low energy region is almost similar for all crystals measured in this study, while the higher energy modes shift to higher energy by increasing the potassium concentration. Anomalous softening of highest energy phonon has been observed across the insulator–superconductor transition around q∼0.25. Observation of the softening in the superconducting samples indicates a correlation between the softening and superconductivity in this system.     

Influence of a fine talc on the properties of composites with high density polyethylene and polyethylene/polystyrene blends

Fine talc filled high density polyethylene (HDPE) and HDPE/polystyrene (PS) blends were extruded, injection moulded and characterized. Some of the mechanical properties of the talc filled HDPE and talc filled 75/25 HDPE/PS blend were deduced from stress–strain measurements. A comparison between the effect of the talc on the properties of the filled HDPE and filled 75/25 HDPE/PS blend showed that the mineral filler had the same effect on both systems provided that its array in the organic matrix is almost the same in both cases. In fact, the rheological results proved that the dispersion of talc in the HDPE matrix was not really affected by the presence of PS. The study particularly focused on the effect of talc on the ultimate tensile strength of the filled HDPE and that of the filled blend. It has been noted that the brittle nature of PS neutralizes, to a certain extent, the degrading effect of talc on this property. Furthermore, both PS and talc have a complementary effect on the stiffness and the resilience of HDPE/PS/talc blend composites.     

NR/CSM/biogenic silica rubber blend composites

Biogenic silica (BSi) was added at different ratios to some polymer blends of polyisoprene rubber (NR) and chlorosulphonated polyethylene rubber (CSM) cured by conventional sulfur system. The reinforcing performance of the filler was investigated using rheometric, mechanical and swelling measurements, differential scanning calorimetry (DSC), thermogravimetric (TGA) and scanning electron microscopy (SEM) analysis. There was a remarkable decrease in the optimum cure time (t_c90) and the scorch time (t_s2), which was associated with an increase in the cure rate index (CRI), with filler loading up to 30 phr in the different blend ratios. The tensile strength and hardness was 4–5 Sh-A higher in the case for the different blend compositions, while the resistance to swelling in toluene became higher. SEM photographs show that the filler is located at the interface between the different polymers which induces compatibilization in the immiscible blends. DSC scans of the filled blends showed shifts in the glass transition temperatures Tg which can be attributed to the improve interfacial bonding between filler and NR/CSM matrix. A higher thermal stability of NR/CSM/BSi composites was detected.     

Fatigue Damage Characterization by NDT in Polypropylene/Glass Fibre Composites

This paper presents the results of a study on glass-fibre-reinforced polypropylene composite in which the fatigue damage was investigated in terms of residual stiffness and temperature rise. Thermographic and acoustic emission techniques were used to aid the interpretation the fatigue damage mechanisms. Different laminates were tested. For one series, all the layers have one of the two fibre directions oriented with the axis of the plate. For the other two series layer distribution was obtained with the following laminate orientation in respect to the axis of the sheet: +45°/0°/−45°/0°/+45°/0°/−45° and +30°/−30°/+30°/0°/+30°/−30°/+30°. It was possible to conclude that the residual stiffness and temperature rise can be used to predict final failure of a structure and/or component. With thermographic technique it is possible to obtain temperature maps and the precise site where the failure will occur.