Adhesion-active compositions based on modified low-molecular-weight polyolefins

This paper presents the results of studies aimed at developing an adhesion-active composition based low-molecular-weight polyethylene modified by polyacrylic-acid polymer complexes and ?-caprolactam with different ratios of components. The optimal composition and amount of the modifying agent were determined based on their effect on the tackiness and adhesive properties of the composition. It is shown that the properties of the developed composition allow it to be recommended for the use as a building mastic and basis for labeling adhesives and compositions for application to polymeric films.     

Composite materials based on modified butadiene-styrene rubber

Effect of fabrication procedure of rubber stocks on the strength and fatigue performance of composite materials based on modified butadiene-styrene rubber was examined.     

The use of industrial oligomers modified by diisocyanates as adhesive and sealing compositions of different purposes

Methods for effective substitution of the traditional polymer-composite materials (PCM) during mounting of an electronic device by new-generation PCMs, including ones based on epoxyurethane oligomers (EPUR oligomers), are suggested. The processes of production of a complex of EPUR oligomer properties and polymers based on them are investigated.     

Adhesive compounds based on natural rubber,modified by nitrogen-containing compounds

The possibility of modifying adhesive compounds based on natural rubber by nitrogen-containing adhesion promoters has been studied. It was shown that the properties of modified adhesive compounds based on natural rubber are comparable to those of adhesive compounds based on polychloroprene, as well as that the implementation of the elaborated technology will enable one to obtain high-strength constructions based on different rubbers.     

Influence of maleic anydrate on properties of incongealable sealants based on butyl rubber

The possibility of using butyl rubber modified by maleic anhydrate as an adhesive additive and obtaining incongealable composites on its basis are shown.     

Effect of calcium carbonate on the properties of noncuring sealants based on butyl rubber and thermoplastics

The effect of the content, dispersity, and surface polarity of calcium carbonate on the physicomechanical and rheological properties of filled noncuring hot melt sealant formulations based on butyl rubber and various thermoplastics was examined. In the formulations based on nonpolar polymers, the cohesion strength and viscosity increase with an increase in the content and dispersity of calcium carbonate, with the strongest reinforcing effect observed with hydrophobized grades of calcium carbonate. With an increase in the polarity of the polymer base, untreated natural carbonate (chalk) becomes more efficient.     

Radiation-induced degradation of butyl rubber vulcanized by three different crosslinking systems

Butyl rubber (IIR) is an isobutylene/isoprene copolymer and is provided with good properties including low permeability to gases, good thermal stability and high resistance to oxygen and ozone action, among others. It is well known that the major effect of ionizing radiations on butyl rubber is chain scission accompanied with a significant reduction in molar mass. This work aimed to study the effects of gamma radiation on the properties of butyl rubbers vulcanized by three different curing systems, such as, the ones based on sulfur, sulfur donor and phenolic resin to identify which curing system is the most stable under irradiation. The butyl rubber vulcanized by three different systems was gamma irradiated with doses of 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 kGy. Irradiated and non-irradiated samples were characterized by the following techniques: tensile, elongation and hardness. It was observed that doses higher than 150 kGy practically destroy the assessed properties for all butyl compounds, irrespective of the vulcanization system used; however compounds cured with phenolic resin showed a decrease in properties proportional to the dose.     

Investigation of the oxidative cleavage of butyl rubber by selective catalysis

Selective oxidizing cleavage of carbon-carbon double bonds of unsaturated polymers leads to bifunctional oligomers. It is shown, using ruthenium tetroxide in catalytic amount in conjunction with a peracid as co-oxidizing agent, that efficient cleavage of butyl rubber double bonds can be obtained without side reaction. The procedure can be used for analytical as well as for synthetic purpose.     

Biodegradable compositions by reactive processing of aliphatic polyester/polysaccharide blends

Commercially available biodegradable aliphatic polyesters, i.e., high molecular weight poly(ϵ-caprolactone) (PCL) and polylactide (PLA), were melt blended with a well-known natural and biodegradable polysaccharide: starch either as corn starch granules or as thermoplastic corn starch after plasticization with glycerol. Conventional melt blending yielded compositions with poor mechanical performances as a result of lack of interfacial adhesion between the rather hydrophobic polyester matrix and the highly hydrophilic and moisture sensitive starch phase. Interface compatibilization was achieved via two different strategies depending on the nature of the polyester chains. In case of PLA/starch compositions, PLA chains were grafted with maleic anhydride through a free radical reaction conducted by reactive extrusion. The maleic anhydride-grafted PLA chains (MAG-PLA) allowed for reinforcing the interfacial adhesion with granular starch as attested by TEM of cryofracture surface. As far as PCL/starch blends were concerned, the compatibilization was achieved via the interfacial localization of amphiphilic graft copolymers formed by grafting of PCL chains onto a polysaccharide backbone such as dextran. The PCL-grafted polysaccharide copolymers were synthesized by controlled ring-opening polymerization of ϵ-caprolactone proceeding via a coordination-insertion mechanism. These compatibilized PCL/starch compositions displayed much improved mechanical properties as determined by tensile testing as well as a much more rapid biodegradation as measured by composting testing.     

Information media based on electron-donor oligomers

Routes for designing hole-conducting organic polymers for use in photoelectric solar-energy converters and light emitters and primarily for recording, storage, and processing of optical information are considered. New carbazole-containing radially tetrasubstituted silanes and germanes are described. It is shown that the information characteristics of holographic recording media based on oligomer compositions substantially depend on the shapes of the oligomer macromolecules.     

Polymeric materials based on oligodieneurethane-epoxy oligomers

Differential-scanning calorimetry in the dynamic mode was used to study the curing kinetics of a PDI-3AK macromolecular oligodieneurethane-epoxy oligomer with isomethyltetrahydrophthalic anhydride in the presence of a number of catalysts, modifiers, and fillers. The effect of their chemical nature on physicomechanical properties of cured polymers was examined.     

Dynamic mechanical properties of epoxy/novolac system modified with reactive liquid rubber and carbon filler

This paper reports on the work carried out to evaluate the frequency dependent viscoelastic properties of epoxy/novolac compositons modified with a liquid reactive rubber and carbon filler. For epoxy systems modified with elastomer, three typical transitions were observed: the α-relaxation deeply related to the glass transition of epoxy, the β-transition of epoxy, and the glass transition of rubber appeared near to the β-relaxation of epoxy resin. Considering an Arrhenius equation, the activation energies of β-relaxation were estimated. In the region of glass transition and rubbery state the temperature dependence of the shift factor (α_T) was determined through Williams-Landel-Ferry (WLF) equation.     

Chain scission of butyl rubber by nitrogen dioxide in absence and presence of air

The chain scission reaction suffered by butyl rubber due to NO₂ (0.01-1 mm Hg) has been studied in the presence and absence of air. It has also been studied as a function of temperature (25–65°C) at constant NO₂ pressure, again in absence and presence of 1 atm of air. Reaction mechanisms which are in good agreement with the experimental results have been formulated. The synergistic action of O₂ and NO₂ has been pointed out.     

The coating performance of adipic acid modified and methacrylated bisphenol- A based epoxy oligomers

In the present work adipic acid modified and methacrylated bisphenol A based epoxy resins were prepared. The structures of oligomers were characterized by FT-IR. UV curable clear coatings were applied on aluminum substrates. The physical and mechanical properties of UV-cured coatings such as gel content, solvent resistance, hardness, gloss, flexibility and tensile tests were examined. In addition, the thermal behavior of coatings was also evaluated. It is observed that the tensile properties and thermal stabilities of modified epoxy methacrylate coatings mainly depend on the adipic acid content. The best results were obtained with 5 wt% adipic acid modification. Copyright © 2007 John Wiley & Sons, Ltd.     

Toughness of epoxies modified by preformed acrylic rubber particles

A bisphenol-A diglycidyl ether resin, cured with isophorone-diamine at 60°C, was modified by means of preformed core-shell acrylic rubber particles. Blends with rubber contents up to 30 phr by wt were tested. The fracture toughness depended linearly on the amount of rubber and significant improvement was found. No deterioration of temperature resistance was also observed. The viscosity of resin/modifier mixtures was controlled by means of antifoaming agents. A comparison with liquid acrylonitrile-butadiene copolymers showed that core-shell particles are efficacious tougheners. The effect of a bimodal particle size distribution was considered. In the size range investigated (0.2+5μm) no synergic effect was observed.     

A critical review on analytical methods and characterization of butyl and bromobutyl rubber

The molecular structure characterization of butyl and bromobutyl rubber (BIIR) requires the definition of three main parameters: (I) the unsaturation degree of the rubbers, (II) the total bromine content of the BIIRs, and (III) the functional bromine content of the BIIRs. The analytical methods for the determination of the previously mentioned parameters have been described and critically examined in this review.     

Macrospirocyclic oligomers based on carbazole and fluorene

Monodisperse macrospirocyclic oligomers were prepared using self-condensation of the Friedel-Crafts reaction. Through the C-9s of the central fluorene units of four surrounding oligofluorenes, four carbazole units are connected in a series to form a macrocyclic core. These rodlike oligofluorenes form a rigid three-dimensional structure, affording the resulting macrocyclics a high steric hindrance for close interchain packing.     

Epoxy oligomers based on eugenol cyclotriphosphazene derivatives

Oligomers of hexakis(4-allyl-2-methoxyphenoxy)cyclotriphosphazene have been synthesized and their molecular structure studied by X-ray and NMR analysis. The nonplanar character of a phosphazene cycle is established, and the bond lengths P-N and valence angles N-P-N are shown to change in narrow ranges (1.5771–1.5894 Å and 117.80°–118.37°, respectively). During epoxidation of hexakis(4-allyl-2-methoxyphenoxy)cyclotriphosphazene by m-chloroperbenzoic acid or peracetic acid, in addition to hexaepoxy derivatives, the corresponding dimer is formed due to partial intermolecular interaction of epoxy groups.     

Oxidative bromination of isoprenyl links of butyl rubber by the system sodium bromide-sodium hypochlorite-phosphoric acid

Results of studying kinetics of the bromination of isoprenyl links of butyl rubber by the system sodium bromide-sodium hypochlorite-phosphoric acid are presented. Reaction orders with respect to the reagents were determined, and the value of the observable activation energy was estimated.     

Effect of oligomers on the polymer diffusion rate in poly(butyl methacrylate) latex films

The aqueous phase of a poly(butyl methacrylate) (PBMA) latex dispersion contained an oligomeric component that was isolated after sedimentation of the PBMA latex particles. The component contained both water‐soluble PBMA oligomer and some longer chain species that were present as a very fine colloidal dispersion. We describe the isolation and characterization of this component. This component was then added to a purified PBMA latex dispersion from which the aqueous component was previously removed. Latex films were prepared, and in the presence of the oligomeric material, the rate of polymer diffusion in the latex film was strongly enhanced. The magnitude of the enhancement was fit quantitatively to the Fujita–Doolittle equation, indicating that the oligomers acted like a traditional plasticizer to increase the free volume in the system. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3933–3943, 2000