Blends of polyamide1010 with unmodified and maleic‐anhydride‐grafted high‐impact polystyrene

The crystallization behaviors, dynamic mechanical properties, tensile, and morphology features of polyamide1010 (PA1010) blends with the high‐impact polystyrene (HIPS) were examined at a wide composition range. Both unmodified and maleic‐anhydride‐(MA)‐grafted HIPS (HIPS‐g‐MA) were used. It was found that the domain size of HIPS‐g‐MA was much smaller than that of HIPS at the same compositions in the blends. The mechanical performances of PA1010–HIPS‐g‐MA blends were enhanced much more than that of PA1010–HIPS blends. The crystallization temperature of PA1010 shifted towards higher temperature as HIPS‐g‐MA increased from 20 to 50% in the blends. For the blends with a dispersed PA phase (≤35 wt %), the T_c of PA1010 shifted towards lower temperature, from 178 to 83°C. An additional transition was detected at a temperature located between the T_g's of PA1010 and PS. It was associated with the interphase relaxation peak. Its intensity increased with increasing content of PA1010, and the maximum occurred at the composition of PA1010–HIPS‐g‐MA 80/20. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 857–865, 1999     

Use of maleic anhydride–grafted polyethylene as compatibilizer for HDPE–tapioca starch blends: Effects on mechanical properties

Tapioca starch in both glycerol‐plasticized and in unplasticized states was blended with high‐density polyethylene (HDPE) using HDPE‐g‐maleic anhydride as the compatibilizer. The impact and tensile properties of the blends were measured according to ASTM methods. The results reveal that blends containing plasticized starch have better mechanical properties than those containing unplasticized starch. High values of elongation at break at par with those of virgin HDPE could be obtained for blends, even with high loading of plasticized starch. Morphological studies by SEM microscopy of impact‐fractured specimens of such blends revealed a ductile fracture, unlike blends with unplasticized starch at such high loadings, which showed brittle fracture, even with the addition of compatibilizer. In general, blends of HDPE and plasticized starch with added compatibilizer show better mechanical properties than similar blends containing unplasticized starch. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 863–872, 2001     

Adhesion of surface‐grafted low‐density polyethylene plates with enzymatically modified chitosan solutions

An investigation was undertaken on application of dilute chitosan solutions modified by tyrosinase‐catalyzed reaction with 3,4‐dihydroxyphenetylamine (dopamine) to adhesion of the low‐density polyethylene (LDPE) plates surface‐grafted with hydrophilic monomers. Tensile shear adhesive strength effectively increased with an increase in the grafted amount for methacrylic acid‐grafted and acrylic acid‐grafted LDPE (LDPE‐g‐PMAA and LDPE‐g‐PAA) plates. In particular, substrate breaking was observed at higher grafted amounts for LDPE‐g‐PAA plates. The increase in the amino group concentration of the chitosan solutions and molecular mass of the chitosan samples led to the increase in adhesive strength. Adhesive strength of the PE‐g‐PMAA plates prepared at lower monomer concentrations sharply increased at lower grafted amounts, which indicates that the formation of shorter grafted PMAA chains is an effective procedure to increase adhesive strength at lower grafted amounts. Infrared measurements showed that the reaction of quinone derivatives enzymatically generated from dopamine with carboxyl groups was an important factor to increase adhesive strength in addition to the formation of the grafted layers with a high water absorptivity. The above‐mentioned results suggested that enzymatically modified dilute chitosan solutions can be applied to an adhesive to bond polymer substrates. The emphasis is on the fact that water is used as a solvent for preparation of chitosan solutions and photografting without any organic solvents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Blends of high‐density polyethylene with solid silicone additive

Silicone masterbatch (SMB) is a pelletized formulation containing 50% of an ultrahigh molecular‐weight polydimethylsiloxane dispersed in polyethylene. This SMB is designed to be used as an additive in polyethylene‐compatible systems to impart benefits such as processing improvement and modification of surface characteristics. In this work, binary blends of high‐density polyethylene (HDPE) and SMB were prepared by melt‐mixing technique to study the influence of this masterbatch on the processing and mechanical properties of HDPE. Ternary blends were also prepared by the addition of silane‐grafted polyethylene (HDPE‐VTES) as compatibilizer. The blends were analyzed by melting flow rate (MFR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and tensile tests. Data of final torque and MFR showed that SMB improved the processability of pure HDPE. DSC results showed differences in crystalline behavior between binary and ternary blends. In the former, the degree of crystallinity increased up to 10 wt % of SMB content; beyond this concentration, it decreased. In ternary blends, a reverse behavior was observed. The morphologic study showed silicone particles uniformly distributed in HDPE matrix. With high SMB concentration, the addition of HDPE‐VTES significantly reduced the size of silicone particles. In the range of SMB composition studied, the mechanical properties of blends lower slightly compared to pure HDPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2347–2354, 2002     

Modifying adhesion of linear low‐density polyethylene to polypropylene by blending with a homogeneous ethylene copolymer

Adhesion of a Ziegler–Natta catalyzed ethylene copolymer (ZNPE) to polypropylene (PP) was studied by measuring the delamination toughness G of coextruded microlayers by using the T‐peel test. Low values of G compared to a homogeneous copolymer with approximately the same short chain branch (SCB) content were attributed to an amorphous interfacial layer of low molecular weight, highly branched ZNPE fractions. Blending ZNPE with a homogeneous metallocene catalyzed copolymer (mPE) increased G. In this regard, mPE with higher SCB content was more effective than mPE with slightly lower SCB content. The ZNPE interface was mimicked by microlayering ZNPE and ZNPE blends with polystyrene from which the ZNPE layers were easily separated without damage to the surface. Examination with atomic force microscopy revealed a soft coating about 8 nm thick on the surface of the ZNPE layer. Blending with mPE reduced or eliminated the amorphous interfacial layer. It was proposed that mPE increased miscibility of low molecular weight, highly branched fractions of ZNPE and prevented their segregation at the interface. After blending with mPE eliminated the interfacial layer, G increased to a value comparable to that of a homogeneous copolymer with about the same SCB content as ZNPE bulk chains. The increase in G was attributed to epitaxial crystallization of the ethylene copolymer in the absence of an amorphous interfacial layer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 109–115, 2004     

Evaluation and simulation of the peel behavior of polyethylene/polybutene‐1 peel systems

The peel characteristics of sealed low‐density polyethylene/isotactic polybutene‐1 (PE‐LD/iPB‐1) films, with different contents of iPB‐1 up to 20 m.‐% (mass percentage), were evaluated and simulated in dependence on the iPB‐1 content, and in dependence on the peel rate. Sealing involves close contact and localized melting of two films for a few seconds. The required force, to separate the local adhered films, is the peel force, which is influenced, among others, by the content of iPB‐1. The peel force decreases exponentially with increasing iPB‐1 content. Transmission electron microscopy studies reveal a favorable dispersion of the iPB‐1 particles within the seal area, for iPB‐1 concentrations ≥6 m.‐%. Here, the iPB‐1 particles form continuous belt‐like structures, which lead to a stable and reproducible peel process. The investigation of the peel rate‐dependency on the peel characteristics is of important interest for practical applications. The peel force increases with increasing peel rate by an exponential law. A numerical simulation of the present material system proves to be useful to comprehend the peel process, and to understand the peel behavior in further detail. Peel tests of different peel samples were simulated, using a two‐dimensional finite element model, including cohesive zone elements. The established finite element model of the peel process was used to simulate the influence of the modulus of elasticity on the peel behavior. The peel force is independent of the modulus of elasticity, however, the peel initiation value increases with increasing modulus of elasticity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Blends of polyamide 6 with low‐density polyethylene compatibilized with ethylene–methacrylic acid based copolymer ionomers: Effect of neutralizing cations

Blends of polyamide 6 with low‐density polyethylene compatibilized with sodium‐, zinc‐, and lithium‐neutralized ethylene—methacrylic acid ionomers were investigated at 11, 33, and 55 wt % neutralization of the ionomers. Blends of polyamide 6 with low‐density polyethylene without a compatibilizer had poor properties characteristic of incompatible polymer–polymer blends. After the addition of a compatibilizer, tensile properties improved, the modulus drop associated with melting increased to higher temperatures, and the dispersed phase size decreased. The improvement of the mechanical properties and thermomechanical properties was less with the acid copolymer than with the ionomers. Overall, ionomers neutralized with sodium, zinc, or lithium showed little difference in their compatibilization efficiency. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structure and adhesion properties of linear low‐density polyethylene powders grafted with acrylic acid via ultraviolet light

The structure and adhesion properties of linear low‐density polyethylene (LLDPE) powder grafted with acrylic acid (AA) via ultraviolet light (UV) were studied by Fourier transform infrared spectroscopy (FTIR), electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), and water contact angle, peel strength, and graft degree measurements. The results show that the chemically inert LLDPE powder can be graft‐copolymerized with AA via this photografting method. The graft degree increases with the ultraviolet irradiation time. The hydrophilicity of the grafted LLDPE powder and the peel strength of high‐density polyethylene (HDPE)/steel joint with the grafted LLDPE powder used as hot‐melt adhesive are improved considerably, as compared to that with the ungrafted LLDPE powder. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2549–2553, 2006     

Preparation of high‐performance polyethylene via a novel processing method of combining dynamic vulcanization with a silane‐grafted water‐crosslinking technique

A novel processing method of combining dynamic vulcanization with the silane‐grafted water‐crosslinking technique to improve the comprehensive properties of polyethylene (PE) is reported. PE was grafted with vinyl triethoxysilane (VTEO) first, and then, N,N,N′,N′‐ tetragylcidyl‐4,4′‐diaminodiphenylmethane epoxy resin was dynamically cured in a PE‐g‐VTEO matrix through a twin‐screw extruder to prepare PE‐g‐VTEO/epoxy blends. Polyethylene‐graft‐maleic anhydride (PE‐g‐MAH) was used as a compatibilizer to improve the interaction between PE‐g‐VTEO and the epoxy resin. The results show that the novel processing method improved the strength, stiffness, and toughness of the blends, especially the heat resistance of the blends, by the addition of the dynamically cured epoxy resin as the reinforcement. PE‐g‐MAH increased the compatibility between PE‐g‐VTEO and the epoxy resin, which played an important role in the improvement of the comprehensive properties of the blends. In addition, after treatments in both hot air and hot water, the comprehensive properties of blends were further improved, thanks to the further curing reaction of epoxy with PE‐g‐VTEO. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Blends of high density polyethylene and ethylene/1‐octene copolymers: Structure and properties

The morphology formation in the blends comprising a high density polyethylene (HDPE) and selected ethylene/1‐octene copolymers (EOCs) was studied with variation of blend compositions using atomic force microscopy (AFM). The binary HDPE/EOC blends studied showed well phase‐separated structures (macrophase separation) in consistence with individual melting and crystallization behavior of the blend components. For the blends comprising low 1‐octene content copolymers, the lamellar stacks of one of the phases were found to exist side by side with that of the another phase giving rise to leaflet vein‐like appearance. The formation of large HDPE lamellae particularly longer than in the pure state has been explained by considering the different melting points of the blend components. The study of strain induced structural changes in an HDPE/EOC blend revealed that at large strains, the extensive stretching of the soft EOC phase is accompanied by buckling of HDPE lamellar stack along the strain axis and subsequent microfibrils formation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1887–1893, 2007     

Prediction of turbulent gas‐solid flow in a duct with a 90° bend using an Eulerian‐Lagrangian approach

A dilute, particle‐laden turbulent flow in a square cross‐sectioned duct with a 90° bend is modeled using a three‐dimensional Eulerian‐Lagrangian approach. Predictions are based on a second‐moment turbulence closure, with particles simulated using a Lagrangian particle tracking technique, coupled to a particle‐wall interaction algorithm and a random Fourier series method used to model particle dispersion. The performance of the model is tested for a gas‐solid flow in a horizontal‐to‐vertical duct, with predictions showing good agreement with experimental data. In particular, the consistent use of anisotropic and fully three‐dimensional approaches throughout yields predictions that result in fluctuating particle velocities in acceptable agreement with data. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Blending of low‐density polyethylene with vanillin for improved barrier and aroma‐releasing properties in food packaging

Modification of low‐density polyethylene (LDPE) with vanillin to obtain flavored packaging film with improved gas barrier and flavor‐releasing properties has been studied. The modification of LDPE with vanillin was monitored by Fourier transform infrared spectroscopy, wherein the appearance of new peaks at 1704.7, 1673.6, and 1597.2 cm^?1 indicates the incorporation of vanillin into LDPE matrix. Films of uniform thickness were obtained by the extrusion of modified LDPE. Modified LDPE was found to have significantly higher gas barrier properties and grease resistance. Sensory quality of food products viz, doodhpeda (milk‐based solid soft sweet), biscuit, and skimmed milk powder packed in LDPE‐vanillin film showed that the doodhpeda sample had clearly perceptible vanilla aroma, whereas biscuit had marginal aroma and skimmed milk powder did not have noticeable aroma. When viewed in the light of imparting desirable vanilla aroma, results of the study indicated that LDPE‐vanillin film has better prospects as a packaging material for solid sweets with considerable fat content when stored under ambient conditions. The release of vanilla aroma was further confirmed by gas chromatography–mass spectrometery analysis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of branched polyethylene by ethylene homopolymerization with a novel (α‐diimine)nickel complex in the presence of methylaluminoxane

Branched polyethylene (PE) was prepared with a novel (α‐diimine)nickel(II) complex of 2,3‐bis(2,6‐dimethylphenyl)‐butanediimine nickel dichloride {[2,6‐(CH₃)₂C₆H₃? N?C(CH₃)C(CH₃)?N? 2,6‐(CH₃)₂C₆H₃]NiCl₂} activated by methylaluminoxane in the presence of a single ethylene monomer. The influences of various polymerization conditions, including the temperature, Al/Ni molar ratio, Ni catalyst concentration, and time, on the catalytic activity, molecular weight, degree of branching, and branch length of PE were investigated. According to gel permeation chromatography, the weight‐average molecular weights of the polymers obtained ranged from 1.7 × 10⁵ to 6.0 × 10⁵, with narrow molecular weight distributions of 2.0–3.5. The degree of branching in the polymers rapidly increased with the polymerization temperature increasing; this led to highly crystalline to totally amorphous polymers, but it was independent of the Al/Ni molar ratio and catalyst concentration. At polymerization temperatures greater than 20°C, the resultant PE was confirmed by ¹³C‐NMR to contain significant amounts of not only methyl but also ethyl, propyl, butyl, amyl, and long branches (longer than six carbons). The formation of the branches could be illustrated by the chain walking mechanism, which controlled their specific spacing and conformational arrangements with one another. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1123–1132, 2002; DOI 10.1002/app.10398     

Update: An Efficient Synthesis of Poly(ethylene glycol)‐Supported Iron(II) Porphyrin Using a Click Reaction and its Application for the Catalytic Olefination of Aldehydes

The facile synthesis of polyethylene glycol (PEG)‐immobilized iron(II) porphyrin using a copper‐catalyzed azide‐alkyne [3+2] cycloaddition “click” reaction is reported. The prepared complex 5 (PEG‐C₅₁H₃₉FeN₇O) was found to be an efficient catalyst for the selective olefination of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine, and afforded excellent olefin yields with high (E) selectivities. The PEG‐supported catalyst 5 was readily recovered by precipitation and filtration, and was recycled through ten runs without significant activity loss.