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In an earlier paper we considered the effect of polypropylene modified with maleic anhydride (MAGPP) on the properties of in situ composites based on polypropylene (PP) and a thermotropic copolyesteramide (Vectra B). In this paper we consider the effect of MAGPP on the properties of in situ composites based on PP and two different thermotropic copolyesters. It was observed that the MAGPP was nearly...
The α- and β-spherulites in polypropylene (PP) were identified by direct observation in the scanning electron microscope after appropriate etching. The α-phase has a dark contrast while the β-phase is brighter. Results concerning the individual behaviour of α- and β-spherulites in polypropylene samples which have been subjected to tensile and shear loading are reported. Under tensile loading, the...
The tensile response of some simple fibre assemblies is calculated, using the actual stress-strain relationships of constituent fibres. These stress-strain relationships are obtained by a scaling procedure, with distributions of ultimate tensile properties and an average stress-strain curve as input. Two polypropylene fibres with different polydispersity index, but the same weight-average molecular...
Dynamic plane-stress failure has been observed directly in the transmission electron microscope as a function of temperature using a commercially available cooling/straining holder in conjunction with a copper deformation cartridge. The low-temperature cooling stage permits studies of the ductile-brittle transition when the transition is between +23 and -170°C. A change in deformation mode was observed...
A graft polymer based upon acrylic acid-functionalized polypropylene (PP-AA) and PP-AA itself were assessed as compatibilizers for polypropylene/liquid-crystal polymer (PP/LCP) polyblend fibres. It was found that the functional compatibilizer improved interfacial adhesion and thus fibre properties, depending on the type of hot-drawing process used, as well as significantly enhancing the thermal stability...
The effect of maleic anhydride-grafted polypropylene (MAP) on the mechanical properties of three polypropylene/liquid-crystalline polymer (PP/LCP) blends was investigated. Three LCPs were used in the study. One LCP was a poly(ester amide) and the other two LCPs were copolyesters. The tensile properties of the PP/liquid-crystal (LC) poly(ester amide) blend were affected by the addition of MAP to...
The deformation and fracture mechanisms of polypropylene (PP) have been analysed on the basis of instability of plastic deformation in the region of preformed voids under dilatational stress. It was suggested by three-point bending tests of a round notched bar under plane-strain conditions that the toughness of PP depends on the strength of the fibrils of the craze, the density of voids or microcrazes...
Compatibilized polymer blends of isotactic polypropylene, styrene-maleic anhydride copolymer (SMA) and two amino functionalized polyolefins--a rubbery amino functional ethylene propylene copolymer and an amino functional isotactic polypropylene--have been formulated over a wide composition range. Blends containing approximately 25% SMA have a morphology that consists of a continuous polyolefin matrix...
Two types of elastomers grafted with maleic anhydride (MA), an ethylene-propylene random copolymer 9EPR) and a styrene-ethylene/butylene-styrene triblock copolymer (SEBS) were found to function both as impact modifiers and compatibilizers for nylon 6/polypropylene blends. The maleic anhydride grafted to the rubber reacts with the amine end-groups of the polyamide, forming a rubber-nylon 6 graft copolymer...
The morphology of nylon 6/polypropylene blends modified with maleated rubbers, such as styrene-ethylene/butylene-styrene triblock copolymers (SEBS-g-maleic anhydride (MA)) and ethylene-propylene random copolymers (EPR-g-MA), is affected by changes in the level of functionality of the rubber. By adjusting this level of functionality it is possible to induce drastic changes in the morphology of blends...
The processes that occur during the deformation of nylon 6/polypropylene blends modified with maleated rubbers were identified by dilatometric measurements and electron microscopy. These toughening mechanisms were found to depend on the type of rubber used as modifier (ethylene-propylene random copolymer, EPR-g-maleic anhydride (MA), or styrene-ethylene/butylene-styrene triblock copolymer, SEBS-g-MA),...
Formation and build-up of interfacial morphologies along a high-modulus carbon fibre (HMCF), produced by isothermal crystallization in quiescent and sheared melts of isotactic polypropylene (PP), were studied by thermo-optical methods. It was established that in the quiescent melt, the HMCF generates α-transcrystallization due to its strong α-nucleation ability. In the isothermally crystallized...
Drawn polypropylene fibres were produced from as-spun fibres with a paracrystalline structure of low orientation. Drawing was carried out at 60 o C in order to prevent the transformation of the paracrystalline form into the monoclinic structure. The internal texture of the as-spun fibre and of a series of drawn fibres has been investigated by electron microscopy following permanganic etching...
Polypyrrole-polypropylene conducting polymer composite films with good mechanical properties and high electrical conductivity were prepared using a two-direction permeation/diffusion polymerization method. The oxidant used was iron(III) chloride. Polypropylene microporous films prepared by the biaxial stretching technique were used as the matrix material. The maximum conductivity of these composite...
Wide-angle X-ray diffraction has been used to characterize different grades of conventionally injection moulded and shear-controlled-orientation injection moulded isotactic polypropylene. The occurrence of the γ-phase in injection mouldings was discussed in particular. A newly defined γ-phase index is used as a criterion for the characterization of mouldings. The γ-phase was shown to be associated...
The influence of long-term ambient storage conditions in the presence of air has been examined on the thermal and photooxidation of unstabilized polypropylene. Samples of polypropylene have been aged under ambient storage for 12 years together with a control sample kept under refrigeration at -20°C. The samples have been examined using second order-derivative absorption, fluorescence and phosphorescence...
Specimens consisting of high-purity β-phase polypropylene were prepared by adding a bicomponent β-nucleator consisting of equal amounts of pimelic acid and calcium stearate. Scanning electron microscopy (SEM), differential scanning calorimetry (d.s.c.), dynamic mechanical analysis and instrumented drop weight impact tests were used to characterize the morphology, thermal behaviour and the impact...
Ethylene-glycidyl methacrylate copolymer (EGMA) has been investigated as a reactive compatibilizer for the immiscible and incompatible blends of polypropylene (PP) and a liquid crystalline polymer (LCP). The epoxy functional groups of the EGMA copolymer can react with the car☐ylic acid and/or hydroxyl end-groups of the liquid comptalline copolyester. The in situ-formed EGMA-g-LCP copolymer tends to...
The lamellar morphology of melt-crystallized thin film spherulites of isotactic and syndiotactic polypropylene (iPP and sPP) has been investigated by transmission electron microscopy (TEM) in phase contrast conditions. It is found that the arrangement and orientation of the lamellae depend on the crystallization temperature. The spherulitic crystallization of iPP has changed from dominant radial to...
The fracture mechanism of crazing in polypropylene (PP), the molecular weight of which was controlled by several different methods, was examined. The craze strength was improved with increasing number-average molecular weight in all specimens regardless of the weight-average molecular weight. Examination of the number of tie molecules between neighbouring lamellae suggested that craze fracture was...
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