Small-angle x-ray scattering studies of melting

The course of melting of melt-crystallized polyethylene fractions and of a poly(ethylene oxide)-polystyrene-poly(ethylene oxide) triblock copolymer has been followed by small-angle x-ray scattering (SAXS). Changes in the intensity and shape of the SAXS curves indicated that both surface melting and melting over the full crystallite thickness (full-strand melting) take place. Full strand melting is the final, irreversible process. Comparison with an analytical model indicates that in the earlier stages of the irreversible, full-strand process the crystallites melt out randomly throughout the bulk. Later stages may occur by the simultaneous melting of a larger stack of crystallites.

Topochemical Reactions of Monomers with Conjugated Triple-Bonds VII Mechanism of Transition from Monomer to Polymer Phase During Solid-State Polymerisation

The lattice-controlled solid-state polymerisation of three different modifications of 2,4-hexadiin-1,6-diol-bis(phenylurethane) was investigated by X-ray and optical methods. The polymerisation is a homogeneous reaction. The polymer grows in the form of single chains within the crystal of the monomer. The chains extend along a definite crystallographic direction. Monomer and polymer are isomorphous and monomer-polymer single crystals of various compositions are obtained up to a quantitative conversion in the case of modification I or III. Phase separation into a mesomorphic polymer and oriented monomer phase was observed on annealing partially polymerised single-crystals of modification II …

Instabilities of the deformation process in cold drawing of poly(ethylene terephthalate) and other polymers

The relationship between drawing rate and drawing stress was studied for amorphous poly(ethylene terephthalate) (PET) under various experimental conditions. Three types of expriments were performed: simple drawing with necking at constant rate, drawing through a conical die, and drawing at constant stress. Under constant stress conditions a transition between two stable regimes of drawing can be observed. The transition occurs at a critical stress σc at which the rate of neck propagation changes by some orders of magnitude. Such a transition was found both below and above the glass transition of PET. With constant drawing rates instabilities of neck propagation were observed under certain e…

The density of crystals of poly(ethylene terephthalate), (PETP), Qc is checked by X-ray diffraction assuming a triclinic unit cell and the indices of reflections as found by Bunn. The following unit cell dimensions are found: a = 4,48A, b = 5,85A, c = 10,75 A, α = 99,5°, β = 118,4°, and γ = 111,2°. This gives the density Qc as 1,515g/cm3 which is about 4% higher than that reported by Bunn. Negligible differences in spacings for samples annealed at different temperatures (120°C–260°C) have been found. Only for an annealing temperature of 100°C the higher d-values lead to Qc = 1,484g/cm3. For undrawn PETP films annealed at 250°C the same value of Qc as for drawn PETP was obtained on the basis…

Untersuchungen zur Struktur der Paraffinschmelzen mit Hilfe der depolarisierten Lichtstreuung

Es wurde die depolarisierte Lichtstreuung von Paraffinschmelzen in Abhangikeit von der Kettenlange und der Temperatur untersucht. Um eine Aussage uber die in der Schmelze vorhandene Orientierungskorrelation zwischen den Kettensegmenten machen zu konnen, wurden die stosinduzierten Streukomponenten mit einem Ramanspektrometer bestimmt und von der mit einer konventionelle Lichtstreuapparatur gemessenen Gesamtstreuung abgezogen.

Proof of the existence of a glass transition in the surface layers of polyethylene single crystals

Structure and properties of polyethyleneterephthalate crystallized by annealing in the highly oriented state

The structure of polyethyleneterephthalate bristles drawn about five times in the amorphous state and subsequently crystallized at temperatures between 100 and 260‡ C has been studied by means of small-angle X-ray scattering. In addition density, heat of fusion and wide-angle scattering behaviour were measured. For comparison, similar experiments were carried out with undrawn samples. The results showed that the degree of crystallinity of PET cannot be calculated from density data on the basis of a simple two-phase model, since the effective densitiesρc* andρa* of the crystalline and amorphous regions depend strongly on crystallization and drawing conditions. With rising crystallization tem…

On the formation of lamellae during annealing of extended chain crystals of radiation-polymerized trioxane

Abstract The structure changes of radiation-polymerized trioxane taking place during annealing have been studied by means of electron microscopy, X-ray small- and wide-angle scattering, and differential thermal analysis. The original fibrillar crystals, supposedly consisting of extended chains, change into lamellar crystals due to annealing at temperatures between 150° and 190°C. Lamella formation can be connected with the appearance of a long period of about 200A which is not observed in the unannealed sample. During annealing within the same temperature range the X-ray reflections due to the twin structure of the original polytrioxane disappear, whereas the orientation of the fraction wit…

Bei der Kristallisation von Niederdruckpolyathylen aus Losung in dunnsten Filmenerhalt man lamellen-bzw.fibrillenartige Einkristalle, in denen nach Elektronenbeugungsmessungen die Molekulketten senkrecht zur Lamellenbene bzw. zur Langsrichtung der Fibrillen stehen. Die Molekule mussen also gefaltet sein. Bei sehr verschidener Wachstumsgeschwindigkeit der kristallographischen Ebenen entarted die Lamellen zu stabchenartigen Fibrillen. Auch bei der Kristallisation von Losungs- und Schmelzfilmen (bulk-material) kann die Lamellenstruktur nachgewiesen werden. Lamellen bzw. Fibrillien stellen also eine unter sehr verschiedenen Kristallisationsbedingungen entstehende morphologische Grundform dar. E…

STUDIES OF STRUCTURE AND DYNAMICS OF SOLID POLYMERS BY ELASTIC AND INELASTIC NEUTRON SCATTERING

Neutron scattering methods can be applied to solid polymers in order to investigate the structure of the bulk material as well as the nature of the molecular motion. A review of some recently performed studies is presented. Diffusional motion in crystals of chain molecules has been studied by means of quasielastic scattering for the case of n-C33H68 as an example for the relationship between structure and molecular motion. It can be shown that below the so-called rotational transition the paraffin crystals exhibit two types of molecular motion: a translational jump (τt = 0.5 10-8s) and a 180°-rotational jump (τr = 2.5 10-8s). The low frequency vibrations in n-alkanes as models of polyethyle…

Elektronenmikroskopische Untersuchungen zur Stabilität von Suspensionen in makromolekularen Lösungen

On the mechanism of fibril growth in polycarbonate and poly(methyl methacrylate) crazes

Morphology of melt-crystallized linear polyethylene fractions and its dependence on molecular weight and crystallization temperature

Replicas and thin-section electron microscopic studies were made of fractions of linear polyethylene covering the molecular weight range 2.78 × 104 to 6.0 × 106 for a variety of crystallizing conditions. Lamellar crystallites were found under all circumstances; and the supermolecular structure, or crystalline morphology, is in agreement with that previously reported from an analysis of the small-angle light-scattering patterns of the same samples under similar crystallization conditions. Details of the crystalline microstructure are also described, which range from truncated hollow pyramids which degenerate as the molecular weight or the undercooling are increased. From these results, it is…

Änderungen der Gitterstruktur hochpolymerer Einkristalle durch Bestrahlung im Elektronenmikroskop

Die durch Bestrahlung mit Elektronen von 40 bis 80 kV hervorgerufenen Anderungen der Gitterstruktur von Polyathylen(PA)- und Polyoxymethylen(POM)-Einkristallen wurden unterrsucht. Dazu wurden Lage, Intensitat und Linienbreite der Reflexe im Elektronenbeugungsdiagramm in Abhangigkeit von der Bestrahlungsdosis gemessen. Vergleichende Untersuchungen wurden an einem Paraffin (C28H58) durchgefuhrt. Aus den Anderungen der Linienbreite konnte geschlossen werden, das im Falle des PA durch die Vernetzung zwischen benachbarten Ketten Gitterstorungen II. Art (parakristalline Storungen) hervorgerufen werden. Sie fuhren auch zu einer betrachtlichen Aufewitung des Gitters. Im Falle des Paraffins dagegen …

Untersuchungen zu den Anisotropie- und Dichtefluktuationen im Polymethylmethacrylat mit Hilfe der Lichtstreuung

Die Frage der Nahordnung und der Konformation von Kettenmolekulen im amorphen Zustand ist in letzter Zeit haufig diskutiert worden. Insbesondere bestehen verschiedene Meinungen daruber, ob in amorphen Polymeren eine sich uber viele Monomereinheiten erstreckende, weitreichende Parallelisierung von Kettensegmenten und somit eine anisotrope Nahordnungsstruktur auftritt.

über Fehlordnungen in Polyäthylen-Einkristallen

An Polyathylen-Einkristallen wurden Dichtemessungen nach verschiedenen Methoden und rontgenographische Untersuchungen durchgefuhrt. Es zeigte sich, da\ die Dichte der lamellenformigen Kristalle mit der Kristallisationstemperatur zunimmt, aber stets wesentlich kleiner ist (0,960–0,975 g/cm3) als diejenige, die man aus der rontgenographisch ermittelten Elementarzelle berechnen kann (1,000 g/cm3). Daraus folgt, da\ diese Kristalle einen wesentlichen Anteil an fehlgeordneten Bereichen enthalten mussen. Auch die Rontgenstreukurven an Paketen von dichtgepackten Lamellen lassen dies erkennen. Die Weitwinkeldiagramme enthalten neben den vom Kristallgitter herruhrenden Reflexen auch den fur alle Str…

Schmelz- und Rekristallisationsvorgänge bei Polyäthylen-Einkristallen

Die aus verdunnten Losungen hergestellten Einkristalle des Polyathylens waren bereits der Gegenstand zahlreicher Untersuchungen (1), da die Struktur dieser Kristalle von grundsatzlicher Bedeutung fur die Diskussion aller physikalischen Eigenschaften der teilkristallinen Hochpolymeren ist. Insbesondere wurde auch die Frage nach dem Kristallisationsgrad α der sogenannten Einkristalle schon haufig erortert. Diese Grose wurde mit Hilfe verschiedener Methoden in mehreren Laboratorien gemessen, und in der uberwiegenden Mehrzahl der Falle wurde festgestellt, das die Polyathylen-Einkristalle je nach den Kristallisationsbedingungen einen Anteil von 10–20% an nichtkristallisierten kettensequenzen ent…

Calculation of small-angle neutron scattering by macromolecules in the semicrystalline state

The conformation of macromolecules in the semicrystalline state has been studied by various authors with respect to the validity of the adjacent re-entry — or switchboard model by application of small-angle neutron scattering. Analytical as well as Monte-Carlo calculations show that the experimental results for melt crystallized polyethylene and isotactic polypropylene can be interpreted on the basis of the solidification model. In this model it is assumed that crystallization occurs by straightening of coil sequences without a long range diffusion process.

Elektronenbeugungsuntersuchungen an nativer und umgefällter cellulose

Small angle X-ray scattering from amorphous polymers arising from heterogeneities

The small angle X-ray scattering of glassy polymers (PET, PC, PVC, PMMA) and of polymer melts (PE) was studied. The dependence of the intensity scattered at small angles on the sample treatment suggests that neither the inherent structure of the pure polymer phase nor microholes are the origin of the scattering. In agreement with all experimental facts the scattering can be attributed to foreign particles such as for instance stabilizers in the polymer matrix. The consequence of this result is discussed with respect to the nodular structure of the amorphous phase and with respect to structural models of the amorphous phase. The nodular structure is not related to regions of different densit…

Synthese und Eigenschaften molekulareinheitlicher n-Paraffine bis zum C140H282

Die Umsetzung von α,ω-Dihalogenalkanen mit Natrium fuhrt nach anschliesender katalytischer Hydrierung zu einem Paraffingemisch mit diskontinuierlicher Molekulargewichtsverteilung. So enthalt das aus 1.10-Dibromdecan hergestellte Produkt nur Paraffine mit 10, 20, 30 usw. C-Atomen, ein aus 1.20-Dibromeicosan hergestelltes Produkt dagegen nur die Paraffine mit 20, 40, 60 usw. C-Atomen. Diese Paraffingemische wurden gelchromatographisch in die molekulareinheitlichen Verbindungen zerlegt und Paraffine bis C140H282 isoliert. Am Beispiel des C70H142 wurde die Temperaturabhangigkeit der Rontgenkleinwinkelstreuung gemessen. Aus Intensitat und Lage der Langperiodenreflexe liesen sich die Anderungen v…

Das Grenzflächenschmelzen der Kristallite in teilkristallisierten Hochpolymeren

Characterization of semicrystalline random copolymers by small-angle neutron scattering

A new method is introduced to determine the degree of partitioning of noncrystallizable comonomer units (B units) between the two phases of a semicrystalline random copolymer. The method is based on the comparison of the intensities of small-angle neutron and x-ray scattering (SANS and SAXS, respectively). By this technique two quantities can be evaluated: the difference Δρ of the mass densities between the crystalline and the disordered regions, and the concentration fluctuations of the B units in the two phases. It is found that SANS is very sensitive to the presence of small amounts of B units if their scattering length is sufficiently different from that of the A units. This will be the…

A new method for data evaluation of small angle neutron scattering experiments and its application to amorphous polycarbonate

The conformation of single chains in bulk polymer materials can be evaluated from coherent neutron scattering on mixtures of normal and deuterated polymers. It is shown that the single-chain structure factor can be also obtained from measurements of highly concentrated mixtures and the procedure of evaluation is described. The application to amorphous polycarbonate demonstrates the advantages of the method.

Studies of structure and dynamics of solid polymers by elastic and inelastic neutron scattering

Abstract Neutron scattering methods can be applied to solid polymers in order to investigate the structure of the bulk material as well as the nature of the molecular motion. A review of some recently performed studies is presented. Diffusional motion in crystals of chain molecules has been studied by means of quasielastic scattering for the case of n-C33H68 as an example for the relationship between structure and molecular motion. It can be shown that below the so-called rotational transition the paraffin crystals exhibit two types of molecular motion: a translational jump (τt = 0.5 10-8s) and a 180°-rotational jump (τr = 2.5 10-8s). The low frequency vibrations in n-alkanes as models of p…

Das Wachstum von Polymerketten im Kristallgitter des Monomeren

Einige niedermolekulare Verbindungen mit konjugierten Dreifachbindungen als Strukturelement konnen im festen, kristallinen Zustand polymerisiert werden. Die Polymerisation tritt bei Bestrahlung der Monomerkristalle mit Rontgenoder UV-Licht oder beim Tempern unterhalb des Schmelzpunktes der jeweiligen Monomermodifikation ein (1–3). Es gelingt mit dieser Methode, Einkristalle des Monomeren in Einkristalle des entsprechenden Polymeren umzuwandeln. Dabei ist die Frage von Interesse, wie die Ketten des topochemisch erzeugten Polymeren im Gitter des Monomeren wachsen. Zwei verschiedene Mechanismen sind denkbar: 1. Im Verlauf der topochemischen Polymerisation konnen die Ketten im Monomergitter ein…

Neutron Scattering of Poly(ethylene terephthalate)

Through the use of deuterium labeling, small angle neutron scattering (SANS) has been found to be an extremely effective tool for elucidating the structure of polymer molecules in the condensed matter state. In this study, the molecular morphology of poly(ethylene terephthalate) (PET) has been determined under four different conditions: (1) in the glassy state, (2) in the semicrystalline state, (3) after cold-drawing, and (4) after undergoing partial transesterification.

Partielles schmelzen von verstrecktem polyäthylen

Crystal structure and morphology of polymers from solid-state reactions

Some solid-state reactions which give rise to the formation of polymer crystals are discussed and the observation of the nascent polymer morphology is used as a guide-line to learn about the reaction mechanism of solid-state polymerizations. Examples for the following three different mechanisms are treated in detail: (a) crystallization succeeding polymerization, (b) simultaneous polymerization and crystallization, and (c) polymerization in solid solution. The nascent morphology of poly(alkylene)s obtained by Ziegler-Natta catalysis is taken as an example for crystallization succeeding polymerization. Another example is the cationic polymerization of 1,3,5-trioxane from solution. In this ca…

Röntgenkleinwinkel-untersuchungen zur struktur der crazes (fließzonen) in polycarbonat und polymethylmethacrylat

Es wurden Rontgenkleinwinkel-Untersuchungen an Polycarbonat- und Polymethylmethacrylat-Proben mit Crazes durchgefuhrt. Die Streuung in Richtung senkrecht zur Verstreckrichtung zeigt ein scharf ausgepragtes Maximum, das durch interpartikulare Interferenz zwischen den Polymerfibrillen in den Crazes verursacht wird. Der mittlere Fibrillendurchmesser ā kann aus der Lage des Beugungsmaximums und aus dem asymptotischen Verhalten der Streukurve bestimmt werden.

Untersuchungen zum Schmelzverhalten des verstreckten Polyäthylens mit Hilfe der Differential-Thermo-Analyse

Zusammenhänge zwischen der Kolloidstruktur kristalliner Hochpolymerer und ihrem Schmelz- und Rekristallisationsverhalten

Direct evidence for glass transition taking place in the surface layers of solution grown crystals of polybutene-1

Untersuchungen zu den orientierungs- und dichtefluktuationen in amorphen polymeren mit hilfe der lichtstreuung

Es wurden mit einem Lichtstreuphotometer die Orientierungs- und Dichtefluktuationen in den amorphen Polymeren «Polycarbonat» (Poly(oxycarbonyloxy-1,4-phenylenisopropyliden-1,4-phenylen)) und Polystyrol in Abhangigkeit von der Temperatur untersucht. Ferner fuhrten wir erganzende Messungen an Oligomeren des Polystyrols und an der flussig-kristallinen Verbindung 4-Butyl-N-(p-methoxybenzyliden)anilin (MBBA) in der isotropen Phase durch. Aus der Hohe der depolarisierten Lichtstreuung ergab sich, das eine Orientierungskorrelation, wie sie fur einige Bundelmodelle vorgeschlagen wurde, nicht auftritt. Besonders detaillierte Aussagen konnten fur Polystyrol gemacht werden. Die depolarisierte Lichtstr…

Kernresonanz- und Röntgenkleinwinkelmessungen an Polyäthylenoxid-Einkristallen

Untersuchungen zur Ursache der Entstehung von “Extended Chain”-Kristallen des Polyäthylens

Als Mechanismus fur die Bildung von “extended chain”-Kristallen bei der Kristallisation von Polyathylen unter hohen Drucken ist vorgeschlagen worden, das sich zunachst Kristallite mit gefalteten Ketten bilden sollen, die sich dann infolge des Dickenwachstum zu Kristallen mit gestreckten Ketten umwandeln. Um diese Deutung zu uberprufen, wurden Polyathylen-Einkristalle und orientierte Polyathylenproben bei Drucken zwischen 1 und 4200 atm und bei Temperaturen zwischen 115 °C und 220 °C getempert. Die Proben wurden mit Hilfe der Rontgenkleinwinkelstreuung, der Elektronenmikroskopie und der Differential-Thermoanalyse untersucht. In keinem Fall konnte ein Hinweis auf eine Umwandlung zu “extended …

THERMODYNAMICAL EXPLANATION OF LARGE PERIODS IN HIGH POLYMER CRYSTALS AND DRAWN FIBERS

Thermodynamische Stabilit�t makromolekularer Kristalle

The density of free energy of a chain crystal contains two terms of opposed sign dependent on the numberN of chain elements in the straight section of the macromolecules between the surfaces of the crystal perpendicular to thec-axis. The surface energy contributes a positive term decreasing withN. The amplitude Φ of the periodic lattice field opposing the chain translation in thec-axis yields the negative term. Due to the incoherent longitudinal thermal vibration of the four first-order neighbours of any chain the fieldΦ is smeared out. Its amplitude decreases the more the higherN and hence yields an increase in free energy density with increasingN. As a consequence of the opposite sign of …

Über Zusammenhänge zwischen der Röntgenkleinwinkelstreuung und der morphologischen Struktur verstreckter Hochpolymerer

In der vorliegenden Arbeit wird uber Versuche berichtet, die Ergebnisse der Rontgenkleinwinkelstreuung an verstreckten Hochpolymeren mit Hilfe von elektronenmikroskopisch beobachtbaren Strukturen zu deuten. Geeignet behandelte elektronenmikroskopische Aufnahmen lassen sich als optische Gitter fur Lichtbeugungsversuche verwenden. Die daran erhaltenen Lichtbeugungsdiagramme zeigen eine Intensitatsverteilung, die mit der rontgenographisch gemessenen gut ubereinstimmt. Es lies sich zeigen, das die elektronenmikroskopisch an verschiedenen verstreckten Hochpolymeren (Polyathylen, Polyoxymethylen und Polyathylenterephthalat) gefundenen periodischen Querstrukturen nicht nur ihrem mittleren Abstand …

Die morphologische Struktur von Copolymeren des Äthylens abhängig von den Gegebenheiten des Molekülbaues

Elektronenmikroskopische Aufnahmen an Copolymeren des Athylens belegen im Beispiel losungskristallisierter Proben in Ubereinstimmung mit einfachen theoretischen Uberlegungen, das das morphologische Erscheinungsbild mit wachsender Unregelmasigkeit im Molekulbau aus einem lamellar-regelmasigen Typ in unregelmasige flussigkeitsahnliche Strukturen ubergeht. Fur schmelzkristallisierte Proben mus man ahnliche Gesetzmasigkeiten erwarten, wenn der Kristallanteil sowie die Verteilung der Kristalle einschlieslich deren Grosenstatistik sich im morphologischen Erscheinungsbild ausdrucken sollen. Man findet an Oberflachen schmelzkristallisierter Filme jedoch nur einen sehr losen Zusammenhang mit den gen…

Conformation of polyethylene molecules in the melt as revealed by small-angle neutron scattering

Thermal density fluctuations in amorphous polymers as revealed by small angle X-ray diffraction

In the case of equilibrium the mean square relative fluctuations of the thermodynamic parameters vanish asymptotically as the number of degrees of freedom approach infinity. There are various observable effects, however, which are related to local fluctuations of the thermodynamic quantities within small parts of the macroscopic system. In particular the scattering of electromagnetic waves by a one-component, one-phase system is due to thermal density fluctuations within small volumes V of the sample. Considering a grand canonical ensemble the phenomenological theory of local fluctuations (1) for a one component system shows that the fluctuation of the number of particles N in the volume V …

Elektronenmikroskopische Untersuchungen an verstrecktem Polyäthylen

The neutron scattering from mixtures of deuterated and undeuterated poly(ethylene oxide), (D-PEO, H-PEO), in the small angle and intermediate angle region has been measured in the melt. We found no indications of a molecular segregation. The value of molecular weight evaluated agreed with that obtained by other methods. For a sample with a molar mass of 120000 g/mol the radius of gyration 〈rw2〉1/2 was found to be 13,6 nm, which corresponds to a characteristic ratio of C = 6,9. The form factor of a single chain can be described by the Debye equation for a random coil with the same unperturbed dimensions. Our results are compared with rotational isomeric state calculations and measurements in…

A remark on the surface structure of polyethylene single crystals

Orientierte Kristallisation des Polyäthylens auf Steinsalz

Thermodynamic theory of finite thickness of polyethylene crystals

Chain conformation and structure in amorphous polymers as revealed by X-ray, neutron, light and electron diffraction

Abstract The physical structure of the melt, the supercooled melt, and the glassy state of amorphous polymers can be characterized by the chain conformation, the local order, and the morphology. The conformation was studied by small-angle neutron scattering. The local order was characterized by pair distribution functions which were derived from electron scattering curves. In addition, model calculations were used to gain information about short-range order. The morphology was studied by means of light scattering (density and anisotropy fluctuations), small-angle X-ray scattering (density fluctuations), and magnetic birefringence measurements (orientational order). Experiments were performe…

Relationship between structure of drawn polymers and molecular motion

In order to study the relationship between structure and molecular motion, drawn polymers are more suitable than isotropic samples since their morphology can be characterized more easily by quantitative methods such as small angle X-ray scattering (SAXS) and electron microscopy (EM). The effects of changes in morphological structure on molecular motion are demonstrated by comparing the results of the SAXS and EM measurements with the dynamic mechanical behavior of drawn polyethylene. In addition the NMR broad line spectra of these samples were analyzed and the influence of annealing conditions and external stress was investigated.

Determination of degree of crystallinity of drawn polymers by means of density measurements

The well known procedure of determining the degree of crystallinity by means of measuring the density presupposes the knowledge of both the densities ρc and ρa of the crystalline and of the noncrystalline regions. By combination of small-angle and wide-angle x-ray scattering and of density measurements it can be shown that this method is not justified in the case of drawn polyethylene if the values of ρc and ρa known from isotropic material are used. Both ρc and ρa depend considerably on annealing and drawing conditions. In addition the effective density ρc* of the more densely packed phase in a two-phase structure is much lower than the value ρc calculated from the positions of the x-ray r…

The temperature dependences of the absolute small angle X-ray scattering powers and of the unit cell spacings of a series of 1,3,5-trioxane—1,3-dioxolane copolymers were measured. From a comparison of these data and of the specific volume values measured by Wilski it is concluded that values of crystallinity calculated in a conventional manner provide meaningful parameters when discussing the microstructure of these materials. The measurements were made on annealed samples. At temperatures below the original annealing temperatures changes in small angle scattering power, long periods and crystallinities of the samples were observed. These changes were reversible with temperature and were to…

Effect of filtration conditions on the apparent density of the intercrystalline layers of polyethylene single crystal mats