Combined modification of asphalt with polyethylene packaging waste and organophilic montmorillonite

Organophilic montmorillonite (OMMT) was prepared via ion exchange of Ca-montmorillonite (Ca-MMT) using dioctadecyl dimethyl ammonium chloride (DDAC). The OMMT and polyethylene packaging waste (WPE) were used as a combined modifier for asphalt, and the microstructure and performance of the modified asphalt were studied. Results show that the organophilic modification with DDAC results in an obvious increase of interlayer spacing of Ca-MMT, and the OMMT nano-lamellas can be completely exfoliated during the preparation of modified asphalt. The WPE, dispersed in asphalt, exhibits relatively small particles with homogeneous distribution, indicating that the OMMT addition is beneficial for the dispersion of WPE in asphalt. Compared with ordinary polymer modified asphalt, the penetration, softening point and ductility of the modified asphalt are all markedly improved. The modified asphalt obtained possesses excellent high-temperature stability, low-temperature anti-cracking performance and deformation resistance.     

DCLR与TLA共混改性沥青的性能对比

以SK-90沥青为基质沥青,分别加入相同掺量(与沥青质量比为5%、10%、15%和20%)的DCLR和TLA,利用SHRP PG、针入度分级体系、红外光谱仪和凝胶色谱仪对比分析DCLR和TLA共混改性沥青的宏观性能和微观结构的变化。结果表明,DCLR和TLA的加入均可以改善沥青的高温性能,但对沥青的低温性能和疲劳性能产生一定的不利影响。同时,根据DCLR和TLA共混改性沥青的官能团和分子量分布的变化可以判断DCLR和TLA对沥青的改性作用主要为物理改性,在某种程度上,DCLR不能完全替代TLA。     

Preparation and characterization of an asphalt-modifying agent with waste packaging polyethylene and organic montmorillonite

In this paper, waste packaging polyethylene (WPE)/organic montmorillonite (OMMT) nanocomposites were prepared and used as an asphalt-modifying agent. The structure and morphology of the nanocomposites and the effects of OMMT on the thermal properties of WPE were investigated. The influence of the microcosmic effects and physical properties of the composite agents on the base asphalt were also studied. The results show that the WPE/OMMT asphalt-modifying agents are exfoliated nanocomposites. When compared with WPE, the melting range of the composites decreases and the thermal stability is improved. In addition, the composite agents not only promote good dispersion of WPE in asphalt, but also improve the low temperature properties of WPE-modified asphalt without adversely affecting its excellent high temperature properties. Therefore, from an environmental and economic standpoint, it is a novel and significant attempt at dealing with waste plastics packaging.     

Microwave assisted fabrication of polymethyl methacrylate-graphene composite nanoparticles applied for the preparation of SBS modified asphalt with enhanced high temperature performance

In order to improve the high temperature rutting resistance ability and stability of styrene-butadiene-styrene (SBS) modified asphalt, microwave heating emulsion polymerization strategy was used to prepare polymethyl methacrylate (PMMA) and graphene nanoparticles (GNPs) composite (PMMA-GNPs) which was used to prepare PMMA-GNPs/SBS modified asphalt. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis characterizations showed that PMMA-GNPs particles were successfully prepared having a weight ratio of GNPs: PMMA of 1:9. Microwave heating reduced the reaction time from 5 h to 30 min compared to conventional oil bath heating. Dynamic shear rheological test and multi-stress creep recovery test confirmed that 0.06% PMMA-GNPs/SBS modified asphalt (0.06% PMMA-GNPs of the mass of base asphalt) exhibited an increase of 14.2% in elastic modulus (G′), while rutting resistance was enhanced and sensitivity to stress changes was reduced as compared to those of 5% SBS modified asphalt. Fluorescence microscopy analysis and phase separation test revealed that an appropriate amount of PMMA-GNPs can be uniformly dispersed in SBS modified asphalt and enhance the mutual interaction of SBS with base asphalt. Based on the results of mechanical tests and characterizations, a suitable modification mechanism of PMMA-GNPs particles in the original SBS modified asphalt was described in detail. This study proposes a simple, cost effective and fast strategy for the preparation of PMMA-GNPs incorporated SBS modified asphalt and hence can be envisioned of great promise in construction and highway industries.     

Morphology influence on the permeation properties of styrene and polystyrene modified polyethylene membranes

Influence of the structure of styrene and polystyrene modified PE membranes on their permeation properties is presented. It is demonstrated that the temperature of styrene treatment (N membranes) and the presence of polystyrene (P membranes) results in high differentiation of the permeation properties. SALS studies have shown the structural reorganization depending on modification extent and diffusion of the penetrant. It is also shown that the morphology of the dried films remains unchanged. This work proves that the appropriate modification of PE films results in membranes with controlled permeation behavior.     

Grafting of hyperbranched poly(amidoamine) onto waste tire rubber powder and its potential application as the curing agent for epoxy resin

To realize the high‐valued application of waste tire rubber (WTR), hyperbranched poly(amidoamine) (PAMAM) were synthesized from the surface of WTR powders to endow its chemical reactivity. The hyperbranched PAMAM‐grafted WTR powders containing a large amount of amine groups on their surface were obtained through “divergent procedure.” First, methyl methacrylate‐grafted WTR powders (MMA‐g‐WTR) were prepared by ozone‐induced grafting polymerization. Afterwards, Michael reaction and subsequent amidation reactions were carried out repetitively to obtain hyperbranched PAMAM chains grafted from the surface of the MMA‐g‐WTR powders. The resulting hyperbranched PAMAM‐grafted WTR powders exhibit good dispersibility in water. Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and thermogravimetric analysis demonstrate the successful grafting of hyperbranched PAMAM on WTR surface. The hyperbranched PAMAM‐grafted WTR powder could be utilize as curing agent and potential toughener for epoxy resin due to abundant amine groups and elastomeric feature of WTR. Differential scanning calorimetry shows that the hyperbranched PAMAM‐grafted WTR powders can be used as effective curing agent for epoxy resin. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation of Fe3O4 thin film by the sol-gel method and its magnetic properties

Films consisting of magnetite particles were prepared by the sol-gel method using iron (III) nitrate dissolved in ethylene glycol and 2-methoxyethanol as a new precursor with the aim of decreasing the processing temperatures. Films were annealed under the mixture of hydrogen and nitrogen at various temperatures. Magnetite formation was found to be influenced both by temperature and atmosphere during firing and hydrogenation processes. Typical values of magnetization in saturation and coercive force of films were 440 mT and 196 kA/m, respectively.     

Evaluation of the migration of UV-ink photoinitiators from polyethylene food packaging by supercritical fluid chromatography combined with photodiode array detector and tandem mass spectrometry

UV-ink photoinitiators (PIs), which are used to initiate polymerization reaction for the curing of inks and lacquers, have become a kind of contaminant residues in printing plastic food packaging. The residual PIs in packaging may pose a potential threat to customers. In this work, migration behaviors of 13 PIs from a polyethylene (PE) packaging to food simulants according to regulation EU No 10/2011 were studied by supercritical fluid chromatography combined with photodiode array detector and tandem mass spectrometry (SFC-PDA-MS/MS). The method simultaneously analyzed 13 PIs within 4.5 min and was sensitively with low limits of detection of 0.02–2.16 μg/L, which could meet high throughput analysis for control the quality of food packaging. The migration results revealed that Irgacure 819, Darocure 1173 and TPO, which had low migration rates, should be preferably selected by plastic food packaging manufacture for food safety.     

Structure and properties of (1−x)(0.6Pb(Zn1/3Nb2/3)O3-0.4Pb (Mg1/3Nb2/3)O3)-xPbTiO3 thin films with perovskite phase promoted by polyethylene glycol

The preferential formation of a pyrochlore structure is a knotty problem in the preparation of Pb(Zn_1/3Nb_2/3)O₃ (PZN)-based thin film materials and its presence is significantly detrimental to the dielectric and piezoelectric properties. In this study, 40 mol% of PZN was replaced with Pb(Mg_1/3Nb_2/3)O₃ (PMN) for obtaining a perovskite composition around a morphotropic phase boundary (MPB), (1−x)(0.6PZN-0.4PMN)-xPT ((1−x)PZMN-xPT, PT: PbTiO₃) where x = 0.23. The thin films with this composition were prepared with a polyethylene glycol (PEG) modi-fied sol-gel method on LaAlO₃ substrates. The microstructural evolution of the films on heat treatment was examined with X-ray diffraction. With the aid of PEG, the formation of the pyrochlore phase was suppressed and the perovskite phase formed directly from the amorphous gel film. The multilayer films with a thickness around 0.25 μm showed a single perovskite phase without any detectable pyrochlore structure. Microscopic images showed uniform grain size of a few tens of nanometers. The role of the polymer dramatically promoting the perovskite phase was investigated with the aid of X-ray photoelectron spectroscopy and thermal analysis. The dielectric constant of the obtained film was 4160 at 1 kHz. The film demonstrated typical ferroelectric hysteresis loops and exhibited excellent piezoelectric performance.     

Characterization by inverse gas chromatography of the surface properties of silicas modified by poly(ethylene glycols) and their models (oligomers,diols)

Summary Silicas are modified by esterification of the surface silanol groups either with poly(ethylene glycol), its oligomers or diols of the same chain length. A whole series of samples carrying grafts differing in chemical nature, molecular weight and number are prepared. These samples are examined by inverse gas chromatography. The London component of the surface energy, the acid/base interaction parameter and the enthalpy of adsorption of alkanes and polar probes are measured. It is apparent for PEG-grafted silicas that the most important variable is the surface coverage, i.e., the number of monomer units of the grafted PEG per unit surface area, and not its molecular weight. The fixation of PEG changes drastically the surface properties of the silicas. According to the surface coverage, silica may acquire base-like properties. The strong PEG-silica interactions cause the polymer to adopt a flat configuration by spreading on the solid surface. Grafted diols behave entirely differently: the conformation of the longer grafts is best described by a sandwich structure in which the outer surface layer is formed by associated alcohol groups, whereas the middle part is formed by the highly organized aliphatic parts of the chains. IR spectroscopy supports these conclusions.