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The high brilliance of the Daresbury Synchrotron Radiation Source has been exploited in time-resolved x-ray fibre diffraction of changes in polymer conformation and organisation in response to patterns of mechanical and thermal stress similar to those followed during industrial processing. This has involved the development of a new x-ray camera which can be used in both wide and small angle diffraction and allows uniaxial drawing for draw rates up to 72,000% per minute (i.e. an increase in length by a factor of 720 in one minute) at temperatures from ambient to 400°C. The use of electronic area detectors which display the diffraction pattern while it is recorded allow experiments to be conducted in real-time. The variation in the diffraction is recorded as a series of frames. The time to record a frame can be as short as 40 msecs.

Molecular modeling and diffraction simulation studies of the biphenyl-based poly(ether ketone)s [O−Ar−Ar−O−Ar−CO−Ar−Ar−CO−Ar−]n (3) and [−O−Ar−Ar−CO−Ar−]n (4, Ar = 1,4-phenylene), coupled with data obtained from an oligomer single-crystal study, have enabled their crystal and molecular structures to be determined from X-ray powder data. A crystallographically disordered structure in which the ether and ketone linkages are distributed randomly over the bridging positions of the polymer chain is potentially available to both polymers and undoubtedly occurs in their random 1:2 copolymer (5). The disordered structure is monoclinic (rather than orthorhombic as has previously been proposed), in space group P21/b, with two chains per unit cell. Rietveld refinement of this structure for polymers 3 and 4, based on X-ray powder data, gave final agreement factors (Rwp) of 5.7% and 6.6%, respectively. Analysis of X-ray fiber data by diffraction simulation methods suggests that the disordered structure always predominates for 3 but that a partially ordered arrangement of ether and ketone linkages is present in oriented samples of polymer 4.

A microdeformation stage based on a piezoelectric crystal actuator capable of measuring the force applied to micrometre‐sized polymeric samples is described. Laboratory force/strain measurements on a single strut of an elastomeric polyurethane foam have been conducted for the first time. The device has also been used on the microfocus beamline at the European Synchrotron Radiation Facility to collect microbeam small‐angle X‐ray scattering data simultaneously with strain and force measurements during the time‐resolved tensile deformation of a single strut of elastomeric polyurethane foam.

Summary: Synchrotron radiation has been used to record the diffraction patterns from Poly(ethylene terephthalate) for a range of draw rates (0.1 to 10sec−1) and temperatures (90 to 120°C). The patterns were analysed to derive the development of the

2(cosθ)> order parameter and the rates of crystallisation. The effects of temperature and draw rate can be unified with a WLF time-temperature shift factor. Comparison with estimates of chain relaxation processes show that, when the draw rate is faster than the chain retraction process, the onset of crystallisation is delayed until the end of drawing. Crystallisation is very sensitive to both temperature and orientation and has an approximate 4th power dependence on 2(cosθ)>.

AbstractDeep seismic reflection profiles over the Anglo?Brabant massif in the southern North Sea reveal reflection patterns throughout the crust that are distinctive and which differ significantly from those observed beneath adjacent areas with Mesozoic basins. Comparisons with reflection profiles from other platform areas suggest that the reflection patterns indicate large-scale structural features associated with compressional tectonics. If so, they may represent thrust structures associated with continental accretion of preferred Caledonian age.

The microfocus X‐ray beamline at the European Synchrotron Radiation Facility has been used to investigate the variation in molecular orientation and crystallinity in the wall of a container fabricated from poly(ethylene terephthalate). Two‐dimensional wide‐angle X‐ray scattering patterns were recorded and displayed in real time as the specimen was tracked across the incident X‐ray beam enabling the measurement of textural changes to be made with a spatial resolution of ~2 μm.

Thermal and wide-angle x-ray scattering (wAxs) studies of a new set of copolymers of polyether ether ketone (PEEK) with ether diphenyl ether ketone (EDEK) have been undertaken. The copolymerization modifies the properties of PEEK. At low levels of comonomer content the incorporation of the comonomer unit lowers the melting temperature and reduces the degree of crystallinity. At higher levels the melting point increases towards that of the PEDEK homopolymer.The x-ray structure is very similar to that of PEEK, consistent with rejection of the comonomer at low levels of comonomer content. At high levels the structure is very similar to that of PEDEK while at intermediate levels the structure is found to 'swtich' from that of PEEK to that of PEDEK, consistent with co-crystallization of the two monomer units.

Three linear ppolyaryls, polyetheretherketone (PEEK) polyetherketone (PEK) and polyphenylenesulphide (PPS) have been examined regarding crystal morphologies as obtained from solutions and molecular orientation in melt grown spherulites, the latter involving also experiments on the carbon fibre containing polymer. In addition to the individual features observed in solution grown crystals agreeing with those being reported concurrently from elsewhere, the present coordinated results on three polymers underline the common crystallization behaviour and texture for this family of polymers. These common features comprise the existence of lamellae as symptomatic of chain folding, acicular shapes indicative of uniaxial growth (b being the growth direction in all three cases), and irregular crystal edges. The sheaf development of these crystals then leads readily to a postulated radiolb-axis orientation in spherulites, confirmed directly in melt crystallized samples possessing transcrystalline textures induced by nucleating carbon fibres. Observations on the effect of carbon fibres drew our attention to the combined influence of the crystal nucleating effect and separation distance of these fibres on the resulting crystal texture of the polymer matrix: varying the relative magnitude of the two effects, can even reverse the overall crystal orientation in the sample. Such considerations should be pertinent to crystal texture development in composites with crystaallizable thermoplastic matrices in general.

The x-ray diffraction spectrum of the engineering thermoplastic poly (aryl-ether-ether-ketone), commonly known as PEEK, has been reported in the literature. The unit cell dimensions are consistent with two aryl units per unit cell, while the chemical repeat has three, suggesting that there is not a strict lateral register between chains. The polymer chain packing of crystalline PEEK has been investigated using lattice energy calculations and it is concluded that lateral chain ordering effects are rather unimportant in determining the crystal structure. The crystallographic equivalence of ether and ketone linkages arises due to essentially random chain stacking.

The determination of the thermodynamic equilibrium melting point of a polymer $(T^0_{m})$ by the extrapolation of the melting temperature of its oligomers has been extensively studied in the case of n-alkanes. Nevertheless, a recent publication¹ underlines the difficulty to realize this extrapolation. A new method is presented here, leading to an acceptable extrapolation of PE. The equation proposed may give a better value of Tm because the premelting phenomena is being considered in its development. Moreover, this method can be easily extended to a larger number of polymers, such as PEO, PEEK, PPS, etc. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2563–2571, 1998

Melt drawn fibres of poly(ether-ether-ketone) (PEEK) have been investigated in which various textural effects occur, arising through alignment of self-seeding nuclei, rather than simple orientation on a molecular level. Growth of the seeds can be arrested at different stages, with associated changes in x-ray diffraction patterns.

The paper is the first step in the application of the gold decoration technique described in Part I to the electron-microscopic study of the nature of the fold surface of polyethylene single crystals. It was observed that different areas of the same crystal layer display different decoration densities. It appears that this is due to residual solvent which is retained to different extents by different crystal portions. This assumption is substantiated by the salient observation that the initially slight decoration differences are much accentuated by deliberate flooding of the decorated crystals with a swelling agent. The inference is that the swelling liquid mobilizes some loose elements along the crystal surface, and, consequently, the differences within the same crystal reveal a variable crystal surface as regards surface looseness. With the new technique we are now able to describe and follow these phenomena as a function of the relevant variables. Within the confines of the present work it has already become apparent by this test that, from the usual commercial polymer, surfaces with least looseness are formed toward the end of the crystallization.

AbstractThe directions of the natural remanent magnetization of samples collected from dykes on Lundy have been measured and related to those of Tertiary lava flows in Northern Britain. Evidence is given suggesting that the dykes are Tertiary and pre-Upper Oligocene in age, and that the geomagnetic field was reversed at the time of their intrusion.

The metal decoration technique has been applied to solution-grown polyethylene crystals, to try to elucidate the texture of the fold surface. Several effects have been observed. Zones have been found at surface steps and boundaries which appear to be a characteristic polymeric feature. Differences in metal nucleation density show that the surface texture can vary between crystals and within the same crystal. Interesting features on annealed and melt-crystallized droplets are also reported. Possible interpretations of all these features are suggested.

In a limited temperature range above the clearing point of crystal suspensions, submicroscopic entities representing unmeasurably small portions of the original crystal population may survive whose existence is revealed by crystals nucleated on subsequent cooling [1]. Factors influencing the number of these nuclei and the nature of these nuclei themselves were explored in the case of polyethylene.

The paper demonstrates the potentiality of the self-seeding technique [3] for the growing of single crystals of polyethylene. It is shown that with appropriate measures, uniform single-layer crystals of strictly controlled habit can be obtained. Concrete recipes are given for the growing technique. The habit features are systematized as functions of crystallization temperature and concentration. Novel twin formations with coincident centers arising from this work are described and analyzed. Their origin is correlated with the result suggested by an associated investigation that the nuclei have a multicomponent structure [4]. The advantages of the new crystal-growing technique for other lines of work are pointed out.

AbstractRecent studies concerned with the application of rock magnetism to several geological problems serve to illustrate the scope of the methods at present available. Rock magnetism can usefully be applied to determine the age of a rock or to correlate it with some other. It may be used in studying the structural history of a formation or the thermal history of a rock. The examples cited deal with igneous rocks in Britain, but the methods also apply to some sediments, and possibly to metamorphic rocks.It is stressed that rock magnetism can be applied quite independently of any theory concerning the earth's field. It is necessary only to establish whether the magnetism measured in the laboratory is a true record of that acquired when the rock formed, or at some other known time in its history.

In 1979, the Institute of Geological Sciences commissioned two lines of seismic reflection profile, a technique which has proved successful1for studying crystalline basement. The survey was sited to cross the concealed Variscan Front in southern England, with recording time extended to 12 s two-way time (TWT). Similar profiles in adjacent parts of Europe have suggested that the Variscan Front is characterized by major thrust zones extending to considerable depths2,3. Our profiles, reported here, show good primary reflections to 6 s TWT and give new detail on the nature of Variscan deformation in southern England. Zones of differing reflection character are evident; a northern zone of low northerly apparent dips, a central zone of poor reflector quality, and a southern zone of steeper dips to the SSE. The southern zone is presumed to represent deformed Variscan basement, including several minor thrust planes and a proposed major thrust zone, analogous to similar structures in Europe. Impersistent reflections between 9 and 10 s TWT could possibly relate to the Moho.

RECENT interest in the exploration of the continental shelf around the British Isles prompts us to report briefly on the findings of detailed geophysical surveys across Cardigan Bay and St George's Channel, made by the University of Birmingham between 1965 and 1967. A full account of this work is being prepared. The surveys have included 2,000 km of traverse with a shipborne gravimeter, 2,000 km with a seismic reflexion profiler and a number of seismic refraction lines with ranges up to 8 km.

AS a part of the scientific activity of the Commonwealth Trans-Antarctic Expedition a collection of eight oriented samples was made by Stephenson from dolerite sills and dykes in the region of the Theron Mountains, Shackleton Range and Whichaway Nunataks. The seven intrusions which have been sampled bear petrological affinities with the Karroo Dolerites of South Africa and with the dolerite sills of Tasmania, and are thought to be of comparable age. They intrude flat-lying sediments and show no evidence of post-formational tilting.

An explosion study was undertaken in 1965 to investigate the structure of the crust in the Irish Sea area. The experiment was designed to permit the use of the time term approach to interpret the data. Seismic waves from twenty-five depth charges were recorded at three temporary seismometer stations in Wales and one in Ireland, the Rookhope Borehole and the U.K.A.E.A. array at Eskdalemuir. Detailed geophysical surveys made across Cardigan Bay and St George's Channel have provided information about the shallow structures. Pg, P* and Pn arrivals were identified on the records, and the velocities were calculated to be 6.1, 7.3 and 8.1 kms−1 respectively. Pn was observed only at Eskdalemuir and Rookhope and the value determined represents in effect only an apparent velocity. P*, however, was observed at the Irish and the three Welsh stations, and its velocity and the associated time terms are well determined. The calculated values of the Pg velocity and time terms have relatively large uncertainties, due probably to the heterogeneous nature of this layer. The shallow structures are complex and as a result it is difficult to translate from time terms to interface depths. A simplified crustal model, making use of average values of the time terms, is made up of three crustal layers with interfaces at depths of 4 km and 24 km and the Moho at a depth of 30 km.