Ethylene Butylacrylate Copolymer Research Articles

Influence of the Structure of Acrylate Groups on the Flame Retardant Behavior of Ethylene Acrylate Copolymers Modified with Chalk and Silicone Elastomer

This study treats the flame retardant effects of different ethylene acrylate copolymers used in a chalk and silicone elastomer system, specifically the flame retardant chemistry and behavior at lower temperatures. The presence or absence of ester pyrolysis, formation of ionomers or other crosslinks, viscosity, and the effects of these factors on the formation and stability of the intumescent structure formed during heating are discussed. The effects of the acrylate content and melt flow rate in flame retardant compounds based on ethylene butyl acrylate copolymer and ethylene ethyl acrylate copolymer are examined. Results of oxygen index, cone calorimetry (including visual observations), dripping, viscosity measurement, thermogravimetric analysis, and infrared spectroscopy are reported.

Microwave dielectric properties of carbon black filled polymers under uniaxial tension

Broadband microwave spectroscopy is commonly employed in the determination of the wave transport properties in mesostructured polymers with embedded carbon black particles. However, very little is known on how uniaxial stress affects the effective permittivity of these percolative materials. In this work we carry out a comprehensive study of the complex permittivity spectra of carbon black filled ethylene butylacrylate copolymer which is submitted to a tensile stress up to 45% over the 0.1−3 GHz frequency range and at room temperature. Permittivity measurements indicated large decreases in the real and imaginary parts of the effective permittivity of the axially elongated samples. This set of experiments illustrates that these microwave permittivity data scale as a power law in frequency, where the exponent is strongly sensitive to stress. In addition, we show that our effective permittivity measurements under stress can be explained in terms of the Gaussian molecular network model in the limit of low stress. The observed variation of the effective permittivity is consistent with that reported for related materials, i.e., carbon black filled cross-linked rubber. Our analysis points out to the importance of local properties, i.e., properties associated with specific subsystems (e.g., aggregates of carbon black particles) in understanding the effective dielectric properties of these “macroscopic homogeneous” materials. Improved reliability through real-time monitoring of strain and material parameters (permittivity and permeability) simultaneously will result in significant benefits to the community in many areas, such as aerospace, power, and automotive industries.

Rheological investigation of the influence of acrylate polymers on the modification of asphalt

AbstractThe effect of ethylene, ethylene acrylate and glycidyl methacrylate (EA) terpolymer, and ethylene butyl acrylate (EBA) copolymer on asphalt modification was investigated at 4, 6 and 8% polymer concentrations. Both melt state rheology and asphalt concrete mix (ACM) were investigated. In the melt state analysis, dynamic shear rheology, storage stability, artificial ageing, and performance grading (PG) were studied. The PG grading of polymer modified asphalt (PMA) is correlated to the elastic properties of the polymers. Both resins improved the rheological properties, reduced the temperature susceptibility, showed better storage stability, and increase the upper grading (performance) temperature of the base asphalt. The two polymers showed similar ageing characteristics with little influence on flow activation energy. In asphalt concrete mix analysis, Marshall stability, stripping (durability), resilient modulus, and permanent deformation tests were performed. Polymer‐modified asphalt concrete mix (PMACM) has increased percent retained stability and the resilient modulus when compared with ACM. The elastic modulus of PMA and the resilient modulus of their ACM followed the same trend. Weak influence on water sensitivity was observed, but excellent rutting resistance was obtained for PMACM over ACM. EA (much cheaper than EBA) produced satisfactory properties of PMA and superior ACM properties when blended with the high asphaltenes Arabian asphalt. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3446–3456, 2006

Scaling of the viscoelasticity of highly filled carbon black polyethylene composites above the melting point

Different types of linear low-density polyethylene and ethylene butylacrylate copolymers were mixed with various types of carbon black in amounts between 25 and 40% by weight. Viscoelastic properties were measured using dynamic mechanical analysis applying a frequency sweep. Typically, the complex modulus approaches asymptotically a constant value at small frequencies, which is referred to as ‘yield modulus’. These results were analysed using a scaling approach according to which the complex modulus and the frequency are normalised by the yield modulus and the quotient of the yield modulus and the polymer viscosity, respectively. Thus a master curve is achieved for nearly all samples independent of the polymer and carbon black type and loading. A similar scaling behaviour has been observed earlier for differently concentrated suspensions of carbon black in Newtonian liquids, but not for filled polymers and different carbon blacks. Thus, contributions from polymer and carbon black to the compounds' viscoelastic properties are discussed.

Cloud-point curves of ethylene−(meth)acrylate copolymers in fluid ethene up to high pressures and temperatures—experimental study and PC–SAFT modeling

Cloud-point pressures of ethylene-(meth)acrylic acid ester copolymers in supercritical ethene have been measured to maximum pressures and temperatures of 3000 bar and 533 K, respectively. The copolymers under investigation were prepared in a continuously operated stirred tank reactor (CSTR), which ensures production of chemically homogeneous polymer. After isolation and purification of the copolymer, the phase behavior was mapped out in a discontinuously operated high-pressure cell. The influence of the type and of the content of (meth)acrylate units within the copolymer on cloud-point behavior in mixtures with ethene was systematically studied for ethylene–ethyl acrylate (poly(E-co-EA)), ethylene-propyl acrylate (poly(E-co-PA)), ethylene-methyl methacrylate (poly(E-co-MMA)), and ethylene-butyl methacrylate (poly(E-co-BMA)) copolymers mostly covering the entire comonomer composition range including the limiting homopolymer systems ethene−polyethylene and ethene−poly(meth)acrylate. The data is compared with previously measured cloud-point pressures for ethylene-methyl acrylate and ethylene–butyl acrylate copolymers in fluid ethene. Starting from the limiting ethene−polyethylene system, cloud-point pressures decrease upon increasing the content of polar comonomer segments. For poly(E-co-MA), poly(E-co-EA), poly(E-co-MMA), and poly(E-co-BMA) this tendency is reversed at higher (meth)acrylic acid ester contents where the cloud-point pressures increase again. No such minimum in cloud-point pressure as a function of comonomer content occurs with poly(E-co-PA) and poly(E-co-BA). The variation of cloud-point pressure with copolymer composition is assigned to effects resulting from (i) short-chain branches on the polymer backbone, (ii) intersegmental interactions of carbonyl groups being shielded to different extents by the various types of alkyl ester groups, and (iii) “entropy penalty” contributions associated with the introduction of the α-methyl groups in case of the methacrylates. The experimental cloud-point-pressure curves are satisfactorily modeled by the Perturbed-chain (PC)−statistical associating fluid theory (SAFT) equation of state. The entire set of pure-component parameters and the three binary interaction parameters are independent of temperature, pressure and polymer molecular weight. The parameters from PC–SAFT modeling allow for estimates of the cloud-point behavior of ethene−poly(E-co-(meth)acrylate) systems in wide ranges of pressure and temperature.

Ac conductance and capacitance of carbon black polymer composites during thermal cycling and isothermal annealing

The ac electrical properties of acetylene black composites mixed into ethylene butylacrylate copolymer (EBA) and into poly (methyl methacrylate) (PMMA) have been measured in thermal cycling and isothermal annealing experiments. The results show that changes in electrical properties are due to rearrangement of gaps between the carbon black aggregates. This has been concluded using an exponent z that relates the critical frequency ωc denoting the crossover of the conductivity from the dc-plateau to its frequency-dependent part to the dc conductivity, σdc, according to ωc ∝σdcz. Below the melting range of EBA and the glass transition of PMMA z is about one corresponding to strong variation of the conductivity and weak dependence of the permittivity on the gaps. Above the melting range of EBA z is about 1.5, indicating strong dependence of both the conductivity and the permittivity on the gaps, as predicted by percolation theory. This was not found in the PMMA composites above the glass transition. We conclude that the polymer matrix affects the nature of the gaps between carbon black aggregates, either allowing their size to vary continuously (z about 1) or letting them open and close (z about 1.5).

Rheological properties of SEBS, EVA and EBA polymer modified bitumens

The rheological properties of various polymer modified bitumens were studied. Three bitumens from two different sources were mixed with styrene-ethylenbutylene-styrene (SEBS), ethylene vinyl acetate (EVA) and ethylene butyl acrylate (EBA) copolymers at different polymer contents. The rheological properties of the modified binders were investigated by means of dynamic mechanical analysis and creep test (bending beam rheometer). The results indicated that polymer modification increased binder elastic responses and dynamic moduli at intermediate and high temperatures, and reduced binder complex and stiffness moduli at low temperatures. Polymer modification also reduced temperature susceptibility, glass transition temperature as well as limiting stiffness temperature. The degree of the improvement generally increased with polymer content, but varied with bitumen source/grade and polymer type.

Characterization of bitumens modified with SEBS, EVA and EBA polymers

A laboratory evaluation of the modified bitumens containing styrene-ethylene-butylene-styrene (SEBS), ethylene vinyl acetate (EVA) and ethylene butyl acrylate (EBA) copolymers is presented. The morphology, storage stability and rheological and ageing properties of the modified binders were studied using fluorescence microscopy, dynamic mechanical analysis, creep test (bending beam rheometer) and conventional methods. The results indicated that the morphology and storage stability of the modified binders were largely dependent on the polymer content and were influenced by the characteristics of the base bitumens and the polymers. At a low polymer content (3% by weight), the modified binders showed dispersed polymer particles in a continuous bitumen matrix. At a sufficiently high polymer content (6% by weight), a continuous polymer phase was observed. Regardless of the nature of the two phases, the storage stability of the modified binders decreased as polymer content increased. Polymer modification improved bitumen rheological properties such as increased elastic responses at high temperatures and reduced creep stiffness at low temperatures. The degree of improvement generally increased with polymer content, but varied with bitumen source/grade and polymer type. Polymer modification also influenced bitumen ageing properties. Evaluation of ageing effect was dependent on testing conditions (e.g. temperature and frequency).

Coionomeric mixtures of polyhydroxyethers and ethylene methacrylic acid copolymers. II. Compatibilizers for blends of polybutylene terephthalate and ethylene butyl acrylate copolymers

AbstractBlends of polybutylene terephthalate and ethylene butyl acrylate copolymers were studied at two extreme concentration levels so that each polymer would form, in turn, a particulate dispersed phase. The blends contained 5% by weight of a coionomeric compatibilizer, which was produced from 1 : 1 mixtures of a polyhydroxy ether of bisphenol A and the sodium ionomer of an ethylene methacrylic acid copolymer, using sodium ethoxide to enhance the formation of ionomeric clusters together with an A‐B‐A block oligomer to assist the solubilization of the two ionomeric polymers. In all cases the addition of the coionomeric compatibilizer mixture to the blend was found to decrease the size of the dispersed particles with a concomitant reduction in the interphase gap. It was also observed that the dispersed polymer exhibited a lower level of crystallinity and a slightly lower melting point than when it was present as a matrix, particularly for the case of the ethylene butylacrylate copolymer. The inability of the compatibilizer to completely prevent the formation of an interfacial gap which did not allow the blends to achieve more substantial improvements in mechanical properties, was attributed to the vast difference in crystallization temperature between the two polymers. © 1993 John Wiley & Sons, Inc.

Thermal degradation of EVA and EBA—A comparison. III. Molecular weight changes

AbstractThis is the third in a series of papers in which the thermal degradation of ethylene‐vinyl acetate (EVA) and ethylene‐butyl acrylate (EBA) copolymers are compared. The EBA samples contained 0.8, 1.6, and 5.4 mol % butyl acrylate (BA), respectively, and the EVA samples 1.2 and 6.7 mol % vinyl acetate (VA). The samples were heated in nitrogen in a tubular oven at 285–390°C, for 6–120 min. The molecular weight distribution (MWD), long chain branching, and gel content were analyzed with size exclusion chromatography (SEC). The columns were connected to refractive index, viscometric, and light scattering detectors. EVA gave a pronounced molecular enlargement at all degradation temperatures. In EVA‐6.7, gel was formed at all degradation levels, whereas the low content sample, EVA‐1.2, did not form any visible amount of gel. The strong tendency to molecular enlargement is due to allyl radicals formed after thermal deacetylation and the formation of internal double bonds. These macroradicals will combine or, less frequently, add to double bonds. The EBA copolymers show a more polyethylenelike degradation behavior. At 285°C molecular enlargement dominates, but already at 333°C a net reduction in molecular size is observed. At high temperatures, ester pyrolysis of the BA groups give carboxylic groups and anhydrides. Alkaline treatment will not give any appreciable change in MWD, showing that the anhydride formation is mainly intramolecular. The chain scission increases with the BA content. This is probably due to β‐cleavage of tertiary macroradicals formed in the chain at the acrylate or carboxylic side groups.