ISSN:0032-3888    

DOI:10.1002/pen.760272002

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractEnthalpic interactions between blend components primarily determine the state of miscibility and many of the physical properties of the blend. Recent applications of these thermodynamic considerations are reviewed for a variety of systems, including binary and ternary blends of homopolymers, binary blends of copolymers with homopolymers, and polymer‐solvent mixtures. Recent advances toward predicting polymer blend miscibility through use of a modified quasichemical thermodynamic model and heats of mixing data for liquids are also discusse

ISSN:0032-3888    

DOI:10.1002/pen.760272003

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractIt has been reported that the addition of specific copolymers can improve the mechanical properties of blends of polyethylene with polyamide‐6. One of these, a poly(ethylene‐co‐methacrylic acid) (EMA) containing between 4 and 15 mol % of methacrylic acid units, has often been used. Binary polyethylene/EMA and EMA/polyamide‐6 blends were studied with the hope that the role of EMA as a compatibilizer in polyethylene/EMA/polyamide‐6 ternary blends might be better understood. Differential scanning calorimetry (DSC), laser small‐angle light scattering, and mechanical property results are discussed. DSC measurements show that one component of the binary blends does not modify the crystallinity of the other. However, laser small‐angle light scattering shows that the morphology of the mixtures changes under similar conditions. Tensile properties of polyethylene/EMA binary blends vary linearly as a function of composition, whereas those of EMA/polyamide‐6 blends deviate slightly from linearity. These results indicate no interaction between the crystalline components of the mixtures, and weak interactions in the

ISSN:0032-3888    

DOI:10.1002/pen.760272004

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractBlending of a poly(ether urethane) with a polyphosphonate obtained by phase transfer catalyzed polycondensation of 4,4′‐biphenol and chloromethylphosphonic dichloride generates a phase‐separated material. One phase contains the soft segment of the polyurethane. This has been excluded from a high‐Tgphase that contains ionic species formed mainly by proton transfer and elimination reactions between the hard segment of the polyurethane and the polyphosphonate. Two glass transitions appear in the blend: one close to theTgof the polyphosphonate and one belonging to the excluded soft segment of the polyurethane. The low temperatureTgdecreases with the increasing content of the polyphosphonate, whereas the high temperature transition increases slightly, indicating an increasing purity of the soft segment and the presence of ionic interactions in the hard segment. The presence of ionic interactions is confirmed by NMR analysis of the blend. Comparison of the spectra of the blends with those of the pure components, along with two‐dimensional experiments, indicate a reaction involving the chloromethyl groups of the polyphosphonate and the nitrogens of the pol

ISSN:0032-3888    

DOI:10.1002/pen.760272005

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThe steady state and dynamic shear behavior of linear low density polyethylenes (LLDPE) blended with low density polyethylene (LDPE) and with another LLDPE resin were measured in capillary and parallel plate geometries atT= 150, 190, and 230°C. The extrudate swell and the Bagley correction were determined. It was observed that the pressure correction plays a significant role in capillary flow of LLDPE/LDPE blends–an indication of immiscibility. Several other rheological functions also suggested a phase separation for the system. Nevertheless, the blend behaved as a “compatible” mixture of emulsion type. By contrast, blends of two LLDPE resins show expected miscibility. However, even in this case additivity was not always observed. A new simple method of calculating the relaxation spectrum was developed. The method is analytical and its accuracy depends on adequacy of the semiempirical relation (proposed previously) to describe dynamic viscosity dependence on the test frequency. For all samples the spectrum allowed computation of storage modulus in good agreement with experimental fi

ISSN:0032-3888    

DOI:10.1002/pen.760272006

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThe uniaxial extensional flow at 150°C of two series of blends: I. LLDPE/LLDPE and II. LLDPE/LDPE was examined in full range of concentrations as well as that of accessible in the rheometer strains and strain rates. It was concluded that Series‐I blends containing different LLD‐type polymers are miscible. Their properties can be predicted on the basis of molecular weight and molecular weight distribution. By contrast, excepting low concentration limits, blends of Series‐II are immiscible. Both series show strain hardening, due to higher values of the maximum strain at break. Series‐II seems to be superior (under the test conditions). The stress growth function in shear, computed from the frequency relaxation spectrum, provided a good prediction of the linear viscoelastic component of the stress growth function in uniaxial e

ISSN:0032-3888    

DOI:10.1002/pen.760272007

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractBlends of polycarbonate (PC) and poly(hexamethylene sebacate) (HMS) with two different molecular weights were prepared and their thermal properties were studied via differential scanning calorimetry. It was found that the high molecular weight PC (HPC) and high molecular weight HMS (HHMS) were partially miscible as evidenced by the decrease in glass transition temperature of HPC in the blends. This partial miscibility is attributed to the interaction of the carbonyl dipole of the ester group and the highly polarizable aromatic carbonate structure. When the low molecular weight PC or HMS was used, the compatibility was enhanced because of the increased entropic contribution to the Gibbs free energy of mixing. In all the blends prepared, the PC crystallized as a result of the plasticizing effect of HMS. Bisphenol‐A diphenyl carbonate (dimer) was synthesized and used as the dimeric model of PC. This material was found to be an excellent diluent for HPC. A single glass transition was found in the HPC/dimer system and the temperature was dependent on the composition. The Couchman's equation was found to fit very well the glass transition temperature versus composition relationship for this system. A single glass transition was also found in the HHMS/dimer system. The melting point depression analysis was performed and resulted in a very low heat of fusion for the 100% crystalline HHMS. It may suggest that the dimer and HHMS are not completely miscible in the amorphous regio

ISSN:0032-3888    

DOI:10.1002/pen.760272008

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractIn this paper we discuss PP‐PB blends in which both components are highly crystallizable. It was our intention to try to prepare homogeneous PP‐PB blends, assuming miscibility in the melt, by using the ultraquenching technique and to study the properties of the resulting blends following crystallization from the glass. Due to the possibility of preparing homogenous blends by ultraquenching, it should be interesting to compare the morphology, properties, and crystallization of the glass‐crystallized blends with the melt‐crystallized blends. We conclude that, in general, the above results suggest there is a considerable degree of compatibility, possibly even miscibility, of PP and PB in the melt, but that miscibility is difficult to obtain by ordinary melt mixing pr

ISSN:0032-3888    

DOI:10.1002/pen.760272009

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractRigid rod molecular composites involve molecular level mixing of two polymers having greatly disparate chain conformations (one rodlike and one flexible coil like). Morphology studies have shown that in such materials the bundle diameter of these rigid rod molecules is less than 5 nm. The rigid rod molecule used is poly(para‐phenylene benzobisthiazole) (PPBT). The thermoplastic flexible polymer matrix is Nylon‐66, DuPont's Zytel 42. Thermal analysis studies on these materials indicate that the expectedTgshifts, as observed for blends of two flexible polymers, and depression ofTmwith increased rod molecule composition does not oc

ISSN:0032-3888    

DOI:10.1002/pen.760272010

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThe temperature rising elution fractionation (TREF) technique makes use of the differential crystallizabilities, introduced by short chain branches (SCB), to fractionate polyethylenes (PE) on the basis of the SCB level of any one chain. This allows one to probe the SCB distribution of a polymer. The TREF technique has been applied to blends of PE by recognizing that the two commercial types of low density polyethylene, high pressure (HP‐LDPE) and linear low density (LLDPE), have different short chain branching distributions. Other common copolymers of ethylene, like ethylene vinyl acetate (EVA) or terpolymers like ethylene/propylene/hexadiene (EPDM), also have different SCB types, levels, and distributions and therefore have different TREF behavior. We have constructed a TREF apparatus that can be used in a number of different types of blend studies. The first is an Analytical‐TREF, which gives a profile of the amount of polymer with a given SCB level and can be used to quantify HP‐LDPE/LLDPE blends. We have also modified the technique to construct a stop‐flow TREF apparatus, which enables one to separate fractions on the basis of the branching levels. The fractions can then be analyzed by size exclusion chromatography, IR,13C NMR, or DSC. The use of these TREF techniques to characterize blends of HP‐LDPE/LLDPE, LLDPE/EVA, PE/EPDM, and PE/polyisobutylene is

ISSN:0032-3888    

DOI:10.1002/pen.760272011

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY