Mass,Mobility, Volatility,and Morphology of Soot Particles Generated by a McKenna and Inverted Burner

Particle mass, mobility, volatile mass fraction, effective density, mass concentration, mass–mobility exponent, and particle morphology were measured from soot generated from a premixed flame (McKenna burner) and an inverted diffusion flame over a range of equivalence ratios. It was found that the mass fraction of volatile material on the soot from the McKenna burner could be up to 0.83 at a high equivalence ratio, but there was no measurable volatile material on the soot from the inverted burner. The inverted burner can produce soot at different mass–mobility exponents, ranging from 2.23 to 2.54, over a range of global equivalence ratios of 0.53–0.67, while the mass–mobility exponent ranges from 2.19 to 2.99 for fresh soot and 2.19 to 2.81 for denuded soot for the McKenna burner at equivalence ratios of 2.0–3.75. Transmission electron microscopy analysis of inverted burner soot shows that a range of particle morphologies is present at a given global equivalence ratio, likely due to different local equivalence ratios and flame conditions in the diffusion flame. Primary particle diameter tends to increase with aggregate size, which could contribute to the mass–mobility exponent being well above 2.

Copyright 2013 American Association for Aerosol Research     

Synthesis and photoluminescent properties of poly(aryl ether)s containing alternate emitting and electron‐transporting moieties

A new diphenylbutadiene‐containing bisphenol was successfully synthesized from benzylideneaniline and 4‐propenylanisole via an anil synthetic method. A series of copoly(arylene ether)s consisting of an alternate isolated blue chromophore (diphenylbutadiene) and an electron‐transporting moiety (1,3,4‐oxadiazole) was synthesized and characterized. High molecular weight copoly(arylene ether)s with an inherent viscosity of >0.5 dL/g were prepared by the nucleophilic displacement reaction of oxadiazole‐activated bis‐fluorocompounds with bisphenols. Introduction of ether linkages into the copolymers led to an enhanced solubility in organic solvents such as N,N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidinone (NMP). The resulting copolymers can be cast into tough and transparent films. The copolymers were amorphous in structure with high glass transition temperatures ranging from 182.29 to 194.50°C. They also exhibited good thermal stability with the maximum decomposition temperatures higher than 500°C in nitrogen. The absorption peaks of these copolymers in thin films varied from 375 to 391 nm, while the photoluminescent peaks varied from 410 to 433 nm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1645–1651, 2003     

Process–structure–property relationship in ternary short‐glass‐fiber/elastomer/polypropylene composites

Short‐glass‐fiber (SGF)‐reinforced polypropylene (PP) composites toughened with a styrene/ethylene butylene/styrene (SEBS) triblock copolymer were injection molded after extrusion. Furthermore, a maleic anhydride (MA)‐grafted SEBS copolymer (SEBS‐g‐MA) was used as an impact modifier and compatibilizer. The effects of the processing conditions and compatibilizer on the microstructure and tensile and impact performance of the hybrid composites were investigated. In the route 1 fabrication process, SGF, PP, and SEBS were blended in an extruder twice, and this was followed by injection molding. In route 2, or the sequential blending process, the elastomer and PP were mixed thoroughly before the addition of SGF. In other words, either PP and SEBS or PP and SEBS‐g‐MA pellets were premixed in an extruder. The produced pellets were then blended with SGF in the extruder, and this was followed by injection molding. The SGF/SEBS‐g‐MA/PP hybrid fabricated by the route 2 process exhibited the highest modulus, yield stress, tensile stress at break, Izod impact energy, and Charpy drop weight impact strength among the composites investigated. This was due to the formation of a homogeneous SEBS elastomeric interlayer at the SGF and matrix interface of the SGF/SEBS‐g‐MA/PP hybrid. This SEBS rubbery layer enhanced the interfacial bonding between SGF and the matrix of the SGF/SEBS‐g‐MA/PP hybrid. The correlations between the processing, microstructure, and properties of the hybrids were investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1384–1392, 2003     

Reinforcement of polypropylene using sisal fibers grafted with poly(methyl methacrylate)

Sisal fiber (SF) surface modification was carried out by grafting with methyl methacrylate (MMA) using cerium and ammonium nitrate as initiator. The effects of reaction time, monomer, and initiator concentration on the grafting parameters were systematically investigated. The results showed that MMA was successfully grafted onto the sisal fiber surface. The PMMA‐grafted sisal fibers were melt blended with polypropylene (PP) and then injection molded. The PP/SF composites were characterized by means of thermal analysis, mechanical testing, wide‐angle X‐ray diffraction, and SEM examination. PMMA grafted onto the surface of SF enhanced the intermolecular interaction between the reinforcing SF and PP matrix, improved the dispersion of SF in the PP matrix, and promoted the formation of β‐crystalline PP. These enhanced the thermal stability and mechanical properties of PP/SF composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1055–1064, 2003     

Impact fracture behavior of PP/EPDM/glass bead ternary composites

The effects of glass bead filler content and surface treatment of the glass with a silane coupling agent on the room temperature impact fracture behavior of polypropylene (PP)/ethylene‐propylene‐diene monomer copolymer (EPDM)/glass bead(GB) ternary composites were determined. The volume fraction of EPDM was kept constant at 10%. The impact fracture energy and impact strength of the composites increased with increasing volume fraction of glass beads (?_g). Surface pretreatment of the glass beads had an insignificant effect on the impact behavior. For a fixed filler content, the best impact strength was achieved when untreated glass beads and a maleic anhydride modified EPDM were used. The impact strength exhibited a maximum value at ?_g=15%. Morphology/impact property relationships and an explanation of the toughening mechanisms were developed by comparing the impact properties with scanning electron micrographs of fracture surfaces.     

Effect of Alkyl Phenol from Cashew Nutshell Liquid and Sisal Fiber Reinforcement on Dry Sliding Wear Behavior of Epoxy Resin

A phenalkamine made from the reaction of alkyl phenol from cashew nut shell liquid (CNSL) and alkaylamine was added at three different weight percentages (30%, 40%, and 50%) as a hardener for curing the epoxy polymer. The effect of phenalkamine concentrtation on mechanical and dry sliding wear resistance properties were compared to synthetic aliphatic amine (TETA) cured epoxy network. It was obsererved that incorporation of phenalkamine improves the dry sliding wear resistance property of the epoxy network along with the impact strength and elongation properties. Epoxy composites incorporating sisal fiber placed unidirectionally (either parallel, anti-parallel, or perpendicular to the sliding direction) were prepared in a vacuum infusion process using phenalkamine as a crosslinking agent. It was observered that wear resistance of longitudinally oriented fibers composite was found to be higher owing to the area of fibers exposed to sliding asperities being smaller. With the goal to understand the brittleness behavior of epoxy networks, fractured surfaces of the epoxy networks were analyzed using optical microscope. A correlation was found between the mechanical and wear resistance properties of the epoxy networks.     

Electrical properties of low density polyethylene/ZnO nanocomposites: The effect of thermal treatments

Low density polyethylene (LDPE)/ZnO nanocomposites were prepared by melt compounding followed by annealing or quenching treatment. Electrical properties of the thermally treated nanocomposites were investigated. The results showed that thermal treatments exerted a pronounced effect on the electrical properties of LDPE/ZnO nanocomposites. The dielectric constant of annealed LDPE/ZnO nanocomposites at various ZnO contents was higher than that of quenched nanocomposites. In sharp contrast, the resistivity of annealed LDPE/ZnO nanocomposites was considerably lower than that of quenched samples. The frequency dependence of dielectric constant was much pronounced for both the annealed and quenched LDPE/ZnO nanocomposites associated with the formation of ZnO network as the ZnO volume content reached 52 vol %. The structure–property relationship of the nanocomposites is discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1436–1444, 2006     

Synthesis and properties of poly(aryl ether sulfone)s containing the phthalazinone moiety

Three series of poly(aryl ether sulfone)s (PAESs) containing the phthalazinone moiety in the polymer backbone were synthesized by solution polycondensation of bis(4-chlorophenyl) sulfone with three commercial bisphenols and 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one. Bisphenol-A, hydroquinone, and bis(4-hydroxyphenyl) sulfone, or bisphenol-S, were selected as the commercial bisphenols for copolymerization. The synthesized polymers exhibited very high glass transition temperatures and excellent thermooxidative properties. They also showed superior mechanical properties and fair rheological properties. The introduction of relatively flexible moieties, such as benzene rings, onto the poly(phthalazinone ether sulfone) (PPES) chain led to a decrease in glass transition temperature with respect to the phthalazinone homopolymer. However, the processability of PPES was improved dramatically by the addition of these commercial bisphenols. The properties of synthesized PAESs can be tailored by changing the molar ratios of bisphenols to phthalazinone monomer. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:137–143, 1998     

Cellulose-based Antimicrobial Composites and Applications: A Brief Review

Cellulose-based antimicrobial composites, typically in the form of functional films and cloth, have received much attention in various applications, such as food, medical and textile industries. Cellulose is a natural polymer, and is highly biodegradable, green, and sustainable. Imparting antimicrobial properties to cellulose, will significantly enhance its applications so that its commercial value can be boosted. In this review paper, the use of cellulose for antimicrobial composites’ preparation was discussed. Two different approaches: surface loading/coating and interior embedding, were focused. Three most widely-applied sectors: food, medical and textile industries, were highlighted. Nanocellulose, as a leading-edge cellulose material, its unique application on the antimicrobial composites, was particularly discussed.     

Effects of nitrogen implantation on low cycle fatigue behavior of ferritic Fe-24Cr-4Al stainless alloy

The effects of nitrogen implantation on cyclic deformation response, near-surface dislocation sub-structure, surface slip band formation, crack initiation, and fatigue life under low cycle fatigue of the ferritic Fe-24Cr-4Al stainless alloy were investigated. Implantation was carried out at an energy of 65 keV and at a fluence of 2 × 10¹⁷ ions/cm². Nitrogen implantation resulted in a substantial cyclic hardening in the alloy. Homogeneous planar dislocation arrangements were formed in the near-surface region of implanted specimens after fatigue, while dislocation loop debris and patches were developed in the un-implanted specimens. Moreover, formation of persistent slip bands (PSBs) was greatly suppressed in the surface of the implanted specimens. Nitrogen implantation also resulted in an alteration of the crack initiation mode from the grain boundary to the surface penetration of the PSBs nucleated below the surface layer. Fatigue life improvements after nitrogen implantation could only be obtained when the PSBs were not only suppressed but also homogenized in the implanted surface layer.