ISSN:0032-3888    

DOI:10.1002/pen.760272102

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractPoly(ethylene terephthalate) (PET) offers good properties as a material of choice for various packaging, electronic, and other applications. In these applications in general, the PET articles achieve improved toughness and other physical properties through molecular orientation resulting from stretching at temperatures slightly above itsTg. Without such orientation, these articles suffer from poor impact toughness. We have been investigating modifications of PET for improving toughness and retaining the permeability properties. PET having intrinsic viscosities of 0.5 to 0.7 have been modified with low modulus polymers, particularly ethylene copolymers such as ethylene‐methacrylic acid (EMAA) copolymers. The effect of crystallinity on toughness was determined. The crystallinity was established by Differential Scanning Calorimetry (DSC) techniques. Many of these modified PET compositions have good toughness and permeability barrier properties for various packaging and other controlled permeability applications such as containers and film

ISSN:0032-3888    

DOI:10.1002/pen.760272103

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThe structures and physical properties of four blends of poly(acrylonitrile‐co‐styrene‐g‐butadiene) (ABS) materials with polycaprolactam (PA6) have been characterized. The blends were separated into components by selective solvent extraction and were found to contain different structures: Blend A contained no PA6 grafts. Blend B contained PA6 grafted onto both soluble and insoluble ABS. Blend C contained PA6 grafted onto soluble poly(styrene‐co‐acrylonitrile) (p‐SAN). In Blend D, PA6 was grafted onto both the insoluble ABS and the p‐SAN phases. Transmission electron microscopy showed different morphologies in the blends. Blend A had a co‐continuous, somewhat laminar structure, while Blend D consisted of an ABS phase dispersed in a PA6 continuum. Blends B and C had intermediate structures. All four blends, however, had very similar rheological and physical properties despite the varia

ISSN:0032-3888    

DOI:10.1002/pen.760272104

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThe size of the minor phase in an immiscible polymer blend can have a significant effect on properties such as the impact strength. Few studies, however, have quantitatively considered the parameters controlling the size of the dispersed phase. In this paper, light and scanning electron microscopy have been used to examine the size of the minor phase in polypropylene/polycarbonate blends after melt processing. The size was examined as a function of both the viscosity ratio (p) and the torque ratio (TR). The viscosity ratio is studied in the regions ofp>1 andp<1.phas a marked effect on the morphology of the dispersed phase with the phase size increasing by a factor of 3 to 4 times fromp= 4.5 top= 17.3. Reduction in the size of the minor phase was achieved belowp= 1 with the minimum particle size occurring atp≃ 0.15. The results for these systems indicate the presence of upper and lower limits ofpbeyond which deformation becomes difficult. This is shown to be similar in some respects to the behavior of Newtonian fluids in shear flow, although the upper limit extends beyond that observed in the Newtonian fluid studie

ISSN:0032-3888    

DOI:10.1002/pen.760272105

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractA novel approach is described for the noncontact evaluation of structural morphology in polyblends by light scattering. Optical methods are attractive for the on‐line characterization of translucent materials because they are noninvasive, rapid, and applicable to high temperature materials. One limitation of conventional light‐scattering techniques is their requirement for relatively thin samples in order to avoid multiple‐scattering effects that smear out the details of the light diffraction pattern. The approach described in this paper is meant to circumvent this limitation by resorting to turbidimetric measurements, which provide useful information on the average size, shape, concentration, and orientation of the dispersed phase particles even in the presence of multiple scattering. The sample thickness is no longer restricted, and methods are described by which the near‐surface volume of infinitely thick parts may be inspected with access to a single side of the material. Results are presented for polypropylene‐polycarbonate (PP/PC) samples of different thicknesses and microstructural morphology, including fibrillar‐type oriented

ISSN:0032-3888    

DOI:10.1002/pen.760272106

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractA series of low molecular weight (≈40000) copolymers of methylmethacrylate (MMA) and 4‐(methacryloyloxy)butylpentamethyldisiloxane (MBPD) have been synthesized by free radical polymerization in dimethylformamide solution. The microstructure, as derived from13C NMR spectra, indicates that the copolymers are about 80% syndiotactic with an overall random distribution of mers. At room temperature, copolymers rich in MMA are clear, rigid glasses but become liquid at high MBPD content. Blends of these copolymers with PMMA are all heterogeneous with visible phase separation over most of the composition range. Differential scanning calorimetry studies show the presence of twoTg's when the relative concentration of PMMA to copolymer is high. Blends of two co‐polymers of similar siloxane content produce clear films with no indication of phase separation. The permeability to oxygen at 25°C increases from 0.20 for pure PMMA to 3.0 (fmol/m·s·Pa.) for a copolymer of MMA/MBPD of the mole ratio of 3:1. Evaluation of the permeation behaviors of the blends suggests that blends rich in siloxane exist as a layered structure with the PMMA rich component dominating the observed perm

ISSN:0032-3888    

DOI:10.1002/pen.760272107

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractA range of additives at 7 to 20 wt% loading can increase the stiffness and strength of crosslinked epoxy resins by up to 60%, yet the tensile specimens also fail in a ductile fashion. In additive formulations where little chemical bonding occurs between the additive and the epoxy matrix (e.g., the reaction product of 4‐hydroxyacetanilide and 1,2‐epoxy‐3‐phenoxypropane), the increase in modulus is directly related to the decrease in free volume available for segmental mobility. The increase in strength results from a combination of the increased modulus and an increased fracture energy, A ductile mode of failure occurs because the cured plastic exhibits a large increase in free volume on straining (low Poinsson's ratio). The strain‐induced increase in free volume effectively takes the sample through the glass to rubber transition. In more highly reactive formulations (e.g., the reaction product of 4‐hydroxyacetanilide and vinyl cyclohexene dioxide), chemical bonding effects complicate this simple free volume interpretation, but the occurrence of a ductile failure mode is again related to the free volume increase

ISSN:0032-3888    

DOI:10.1002/pen.760272108

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThis second paper of a series continues the examination of the tensile properties of two series of linear low density polyethylene/polypropylene, (LLDPE/PP) blends. The blends were prepared using a twin‐screw extruder and cover the whole concentration range, An Instron Universal Tensile Tester was used to measure the tensile properties of the blends between 10 and 70°C, and the temperature and composition dependences of the modulus were examined. A comparison is established between the solid state and melt properties to underline the behavior in the PP rich region. Results of dynamic mechanical experiments and differential scanning calorimetry on the same materials are also given, and the mechanical behavior is discussed in terms of the variation of the system's crystallini

ISSN:0032-3888    

DOI:10.1002/pen.760272109

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractReactive polystyrene (OPS) and reactive polyethylene (CPE) with oxazoline and carboxylic acid functionality, respectively, were melt blended in a Rheomix mixer under a variety of conditions. The properties of these blends were examined and correlated with the compositions and mixing conditions such as shear rate, time, and temperature. An increase in torque was observed, which is believed related to chemical reaction between OPS and CPE. The difference between the maximum and minimum torque (Tmax‐Tmin), increases from 48 to a maximum of 510 m‐g for 10 and 40% CPE reacted blends, respectively, But on further increase in the CPE amount in the blend the torque increase drops reaching a final minimum value of 133 m‐g for a blend with 90% CPE. Differential Scanning Calorimetry (DSC) studies reveal a single first order transition, due to CPE, for each of these polymer blends. Furthermore, evidence of the glass transition temperature for OPS diminishes with increasing CPE content and mixing time. Scanning Electron Micrographs (SEM) show a fine dispersion in these reactive blends, with particle size much smaller than a micron. Blends with 50% or more CPE have no distinguishable features as such. Mechanical properties such as elongation at break of reacted blends are improved over the nonreactive polyethylene (PE) and polystyrene (PS) blends. An intermolecular reaction between the OPS and CPE results in a graft polymer, which imparts improvement in the overall properties of these reacted blends. The maximum grafting reaction corresponds to 40% CPE blend, which is being evaluated as a potential compatibi

ISSN:0032-3888    

DOI:10.1002/pen.760272110

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThe phase behavior and mechanical properties of a series of polyarylate/polycarbonate blends were studied. The polymers are known to transesterify, the extent of which depends upon the thermal and shear history and affects phase behavior and properties. Single screw extrusion, twin screw extrusion, and solution casting were employed for blend preparation. Two transition temperatures, corresponding to a polycarbonate‐rich phase and to a polyarylate‐rich phase, were seen in blends that were solution cast or compounded in a single screw extruder at 285°C. But after injection molding a singleTgwas observed, When annealed at 180°C for several hours the molded blend was found to phase separate. Blends that were compounded in a twin screw extruder exhibited a singleTgand could not be phase separated. The flexural and tensile properties of blends that were prepared in a twin screw extruder show a small positive synergism. But the impact properties were substantially below the rule of mixtures values, probably the result of advanced exchange reaction and thermal degrad

ISSN:0032-3888    

DOI:10.1002/pen.760272111

出版商:Society of Plastics Engineers    

年代:1987

数据来源: WILEY