Addition Of Styrene-butadiene-styrene Research Articles

Changes in fractional compositions of PPA and SBS modified asphalt binders

Asphalt binders are complex chemical composites of various organic molecules. They are often modified chemically to obtain some rheological and physical superiority over the unmodified neat binders. The chemical compositions they inherit from their crude origins determine the suitable modification methodologies, which eventually lead to their rheological changes. The changes in chemical compositions due to the modifications of selected asphalt binders with Polyphosphoric Acid (PPA) and Styrene Butadiene Styrene (SBS) were observed in this study. The percentage fractions of Saturates, Aromatics, Resins, and Asphaltenes (SARA) were measured for binders modified with different amounts of PPA and SBS. The Asphaltenes content was found to increase linearly with the addition of PPA and SBS, and so did their viscosity values. Unlike acidic binders (pH < 7.0), basic binders (pH > 7.0) demonstrated a distinctive decline of pH with PPA modifications. The Aromatics and Resins contents had a sharp change after a certain amount of PPA that demonstrated a demarcation point beyond which further addition of PPA would result in no desirable benefits. The demarcation points were different for two different (crude origin) binders. The addition of SBS did not contribute in changing the Asphaltenes content. Rather, SBS changed the Aromatics and Resins contents to yield the desired paving grade binder.

Cell evolution and compressive properties of styrene–butadiene–styrene toughened and calcium carbonate reinforced polystyrene extrusion foams with supercritical carbon dioxide

ABSTRACTPolystyrene (PS) foams have been used in various fields, whereas its broader application is limited by its low mechanical strength and brittle features. In this study, styrene–butadiene–styrene (SBS) and calcium carbonate (CaCO3) nanoparticles were melt‐blended with PS and extrusion‐foamed with supercritical carbon dioxide as a blowing agent to simultaneously toughen and reinforce PS foams. Under the same foaming conditions, the addition of SBS and CaCO3 was shown to have a significant influence on the cell structure and the compressive properties of the composite foams. We found that the cell structure evolution was highly correlated with the system viscosity. When the rubbery‐phase SBS content was 20%, the cell diameter decreased by 20.7%, and the compressive modulus was enhanced by 289.5%. With the further addition of 5% rigid CaCO3 nanoparticles, the cell diameter was further reduced by 72.2% and the compressive modulus was improved by 379.2%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43508.

Physical and rheological properties of crumb rubber/styrene-butadiene-styrene compound modified asphalts

In order to improve the storage stability and tenacity of crumb rubber modified (CRM) asphalt, CRM compound modified asphalt was prepared by the addition of styrene–butadiene–styrene (SBS) and sulfur. The addition of SBS improved the tenacity of CRM asphalt, due to the formation of a dense polymer network. The storage stability of crumb rubber (CR)/SBS-modified (CRSM) asphalt was improved by the addition of sulfur. The rheological tests confirmed the effect of SBS and sulfur on the physical properties of CRM asphalt to some extent and showed the susceptibility of CR/SBS/sulfur-modified (CRSSM) asphalt to dynamic shearing. The morphology observation showed the compatibility of CRSM asphalt was improved greatly by vulcanization. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Visible-light-induced synthesis of pH-responsive composite hydrogels for controlled delivery of the anticonvulsant drug pregabalin

We report here a novel method for the synthesis of a pH-responsive composite using visible light. Formation of the pH-responsive layer is based on poly(methacrylic acid-g-ethylene glycol) as the macromer, eosin Y as the photoinitiator and triethanolamine as the co-initiator. The hydrogel was functionalized with hydrophobic domains through incorporation of crosslinked styrene–butadiene–styrene (SBS) copolymer into the pH-responsive prepolymer. Swelling ratios were decreased with the addition of SBS, and resulted in high hydrogel crosslink density. The composite allowed for controlled release of an anticonvulsant model drug, pregabalin, under neutral pH condition and the release was analyzed to describe the mode of transport through the network. In vitro human fibroblast survival assay and in vivo rabbit implantation experiments demonstrated that this hybrid network is not toxic and has desirable biocompatibility properties. This is the first report about the synthesis of a pH-responsive network incorporating crosslinked SBS synthesized under visible light. The approach for multifunctional membranes could allow the incorporation of molecules with specific functionalities so that sequential molecule delivery in response to specific stimuli could be achieved.

Toughening study of fire‐retardant high‐impact polystyrene

AbstractFire‐retardant high‐impact polystyrene (HIPS) was modified by melt blending with varying amounts of three types of tougheners. The effects of the tougheners on the properties of the fire‐retardant HIPS were studied by mechanical, combustion tests, and thermogravimetric analysis. The morphologies of fracture surfaces and char layers were characterized through scanning electron microscopy. The results show that the impact properties of styrene–butadiene–styrene (SBS)‐containing composites were better than those of ethylene–propylene–diene monomer (EPDM)‐containing or ethylene–vinyl acetate copolymer (EVA)‐containing composites. The tensile strength and flexural modulus of the fire‐retardant HIPS decreased evidently with the addition of tougheners. It is found that the compatibility between SBS copolymer and HIPS matrix was best among the three types of tougheners. The addition of SBS had little influence on the thermal property, residue, flammability, and morphology of char layer of the fire‐retardant HIPS, but the addition of EPDM rubber or EVA brought adverse influence on the residue, flammability, and morphology of char layer of the fire‐retardant HIPS, especially for EPDM. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Flame retardancy and toughening of high impact polystyrene

AbstractFlame retardant high impact polystyrene (HIPS) was prepared by melt blending HIPS, nano‐modified aluminum trihydrate (nano‐CG‐ATH), red phosphorus masterbatch (RPM), and modified polyphenylene oxide (MPPO). Styrene‐butadiene‐styrene (SBS) was used as a toughener in this research. The effects of nano‐CG‐ATH, RPM, MPPO, and SBS on properties of HIPS composites were studied by combustion test, mechanical tests, and thermogravimetric analysis. The morphologies of fracture surfaces and char layers were characterized through scanning electron microscopy (SEM). The HIPS/nano‐CG‐ATH/RPM/MPPO (60/6/9/25) composite and its combustion residues at various temperatures were characterized by Fourier transform infrared (FTIR) spectra analysis. The results showed that the UL‐94 rating of the HIPS/nano‐CG‐ATH/RPM/MPPO (60/6/9/25) composite reached V‐0 and its char layer after flame test was integrated, but its impact strength was low. Addition of SBS improved its impact property and did not influence its thermal and flame retardant properties but lowered its tensile strength and flexural modulus to some extent. The FTIR spectra confirmed that the POC group was present in the charred substance. POLYM. COMPOS., 28:551–559, 2007. © 2007 Society of Plastics Engineers

The Effect of Styrene-Butadiene-Styrene Modification on the Characteristics and Performance of Bitumen

In order to cover the effect of styrene-butadiene-styrene (SBS) modification on the characteristics of bitumen, two types of bitumen, one plain bitumen, and one polymer modified bitumen produced with the plain bitumen as base material were characterized in terms of chemical composition, microstructure, micromechanical properties, and thermoanalytical behavior. In order to determine the complex chemical composition of bitumen, elemental analysis, gel permeation chromatography, and the Iatroscan method were employed. Microstructure and micromechanical properties were determined using an environmental scanning electron microscope and the nanoindentation technique. Modulated differential scanning calorimetry was used to determine phase-change temperatures and endo/exotherms associated with molecular movement. The addition of SBS leads to different rheological behavior over the whole service temperature range. This is reflected in bitumen chemistry by differences in elemental composition and molecular weight distribution with much higher Mw values for the modified bitumen. Accordingly, the polymer leads to a shift in molecular fractions. Electron microscopy reveals two distinct phases building up the bitumen microstructure. The chosen mode of quantification leads to similar material parameters for both bitumens, which is explained by the use of the same base material. In contrast, nanoindentation delivers viscosities in the micro-range corresponding to large-scale rheological properties. Modulated differential scanning calorimetry indicates two glass transitions corresponding with two material phases also confirmed by other experiments. Due to modification, these glass transitions depart from each other and the amount of the two material phases changes, correlating with the shift in molecular fractions observed in Iatroscan analyses.