Vesna Ocelić Bulatović

Effect of polymer modifiers on the properties of bitumen

This article presents an investigation about the polymer-modified bitumens (PMBs) containing styrene–butadiene–styrene (SBS) block copolymers with different structures, linear (SBS-L) and radial (SBS-R), semicrystalline copolymer ethylene–vinyl acetate (EVA), and terpolymer ethylene–butyl acrylate–glycidyl methacrylate, Elvaloy AM and Elvaloy 4170. The aim of the study was to establish the influence of the polymer type and content on the properties of PMBs for engineering applications and to evaluate the effectiveness of polymer modifiers. The results indicated that the polymer modification improved the rheological properties of bitumen, increased critical temperature, that is better resistance to permanent deformation was achieved as well as a wider temperature range in service. The degree of improvement generally increased with the polymer content but varied with the polymer type.

Polymer modified bitumen

Abstract Standard methods of characterisation of bitumen (BIT) and polymer modified bitumen (PMB) do not provide sufficient information. We propose to rely on determination of rheological properties which are much more informative. Along theses lines, we have determined rheology before and after the rolling thin film oven test. The materials studied were BIT, BIT+linear (L), styrene–butadiene–styrene (SBS), block copolymer, BIT+radial (R) and SBS copolymer. The rheological properties of the modified binders are characterised using a dynamic shear rheometer, over wide ranges of temperatures at a fixed traffic frequency of 10 rad s−1. The SBS block copolymers increase the elasticity of the BIT at high temperatures and contribute to a better flexibility at low temperatures. Polymer modified bitumens have higher resistance to permanent deformation. After aging, the hardening of BIT and PMBs occurred and the elastic response decreases as a consequence of degradation. The determined rheological properties are in agreement with the results of conventional tests.

Relationship between fractal, viscoelastic, and aging properties of linear and radial styrene–butadiene–styrene polymer-modified bitumen

The present study is aimed at evaluating the morphological and interfacial properties of the polymer and bitumen (BIT) in linear styrene–butadiene–styrene (SBS-L) block copolymer and radial SBS (SBS-R) block copolymer-modified BIT (PmB) by fractal analysis. Fluorescence microscopy technique coupled with image analysis was used to measure the particle size distribution and fractal dimension of PmB morphology formed in mixtures. Fractal analysis approach was proposed as quantitative description method to evaluate nonuniformity of phase-separated SBS polymer particles/fibrils in PmB. Fractal-like structures in fluorescence micrographs of PmB morphology with the polymer phase-separated particles/fibrils were quantified using interface D[BW], BIT-rich phase D[B+BW], and SBS-rich phase D[W+BW] box-counting fractal dimensions. The overall morphological structure became more compact or more fibril organized as the polymer content attained overcritical values. The relatively high values for the BIT-rich phase D[B+BW] fractal dimension suggests that the PmB mixtures have a structure with extremely high space-filling capacity. Polymer-BIT mixture properties by the conventional laboratory performance tests and by the rheological measurements before and after the Rolling Thin Film Oven Test have been correlated with the PmB mixtures fractal dimensions.

Influence of polymer types on bitumen engineering properties

Abstract In order to achievement new engineering properties, bitumen is mixed with polymers, thereby obtained blends that can have different physical or chemical structures, depending on the composition of the added polymer. The addition of polymers influences the rheological properties of polymer modified bitumens (PMBs), resistance to permanent deformation, PMBs stability under stress and temperature. Along theses lines, the PMBs blends with non-reactive polymers, elastomer styrene–butadiene–styrene with linear and radial structure, thermoplastic polymer ethylene-vinyl acetate and reactive polymer ethylene–butylacrylate–glycidylmethacrylate (Elvaloy), were prepared. Their rheological properties are characterised using dynamic shear rheometer, over wide ranges of temperatures at a fixed traffic frequency of 10 rad s−1 both before and after thermooxidative aging. The aim was to established the influence of the polymer type on the bitumen engineering properties and evaluation of the polymer modifier effectiveness.

Multi-fractal morphology of un-aged and aged SBS polymer-modified bitumen

ABSTRACT Polymer-modified bitumen (PmBs) has been characterised by fluorescence microscopy, conventional performance tests and by the rheological measurements, before and after the Rolling Thin Film Oven Test (RTFOT), and by multi-fractal analysis. The addition of 2–7 wt-% of linear styrene-butadiene-styrene block copolymer (SBS-L) or radial block copolymer (SBS-R) increased viscosity, softening point and complex modulus of PmBs. Hardening of PmBs occurred and the elastic response decreased after RTFOT aging. SBS-L PmBs are more susceptible to RTFOT aging. Digital fluorescence micrographs of sections of PmBs qualitatively exhibit different morphological structures which can be quantitatively probed by multi-fractal analysis: differences are reflected in the f (α) spectrum. The PmBs which appear less multi-fractal have the best rheological properties. In another approach, the focal fractal dimensions’ distributions for the SBS-modified bitumen have peak around 2.35 (which corresponds to the bitumen-rich phase) and around 2.7 (which corresponds to the noncontinuous SBS-rich phase).

The influence of filler treatment on the mechanical properties and phase behavior of thermoplastic polyurethane/polypropylene blends

Thermoplastic polyurethane (TPU) and isotactic polypropylene (iPP) composites and their talc reinforced blends containing untreated and silane treated talc were investigated. The talc surface was modified with organosilane coupling agent in order to improve the polymer–filler interface interaction. TPU has been blended with iPP in a twin screw extruder and samples for investigation were prepared by injection moulding at different concentrations. The neat polymers, composites and blends were characterized with DMA, XRD, FTIR and tensile testing. The obtained results showed that mechanical properties of the talc filled TPU and iPP composites and TPU/iPP blends were improved with the addition of untreated and silane treated talc. The storage modulus of the TPU/iPP blends increased with the addition of untreated and silane treated talc, due to a stiffer interface which talc generated in the polymer matrix. The comparison among samples filled with untreated and silane treated talc filler showed that the polymer composites and TPU/iPP blends filled with silane treated talc displayed better mechanical properties. Silane addition improves the adhesion between the filler and the polymer matrix.

Miscibility of Poly(Vinyl Chloride) with Poly(Ethylene Oxide) of Different Molecular Weights

In this work, five different techniques: dilute solution viscometry, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FT-IR), and scanning electronic microscopy (SEM) were employed in order to evaluate interactions of amorphous poly(vinyl chloride) (PVC) and semi- crystalline poly(ethylene oxide) (PEO) in solution and solid state. The results varied significantly from one experimental technique to another. The positive interactions between the investigated polymers were found over the whole composition range only in solution. However, in the solid state, by DSC and DMA analysis, the positive interactions were found only at elevated PVC content, while FT-IR and SEM analysis could not confirm interactions between the investigated polymers.

Effect of Silane Treated and Untreated Talc on the Properties of Thermoplastic Polyurethane/Polypropylene Blends

The effect of the silane treated talc on the mechanical and thermal properties of talc filled thermoplastic polyurethane/polypropylene blends (TPU/PP blends) was investigated. Thermoplastic polyurethane and polypropylene are partially miscible due to the lack of interfacial interaction between the nonpolar crystalline PP and polar TPU. Blends of TPU and PP with silane treated and untreated-talc were prepared using melt blending in a laboratory twin-screw extruder. Organosilane (3-glycidoxypropyl-trimetoxy silane coupling agent) was used to treat talc in order to improve the affinity between the filler and the TPU/PP blends. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and mechanical (tensile test) measurements were used to characterize the talc filled and silane treated talc filled composites and TPU/PP/talc blends. The addition of silane treated and untreated talc in TPU/PP blends improved miscibility in all investigated TPU/PP/talc blends. The silane treatment increases the storage modulus in all investigated TPU/PP/talc blends in comparison with that of the untreated TPU/PP/talc blends. The obtained DSC results show that the addition of silane treated talc increases the degree of crystallinity (χc) of TPU/PP/talc blends because of the improved adhesion between the polymer and the treated talc. Addition of silane treated talc improved the mechanical properties as compared to TPU/PP/talc blends without chemical modification of talc. The results of strength correlate to the values of the storage modulus and crystallinity of the investigated TPU/PP/talc blends.