Herstellung und eigenschaften von pfropfcopolymerisaten des vinylacetats auf ataktischem polypropylen

The applicability of atactic polypropylene is investigated in the graft polymerization with vinyl acetate. The obtained graft products with different compositions are characterized with reference to swell behaviour, glass transition temperature and graft parameters. After compounding of the graft products with polyvinylchloride the mechanical properties are represented in relation to the quantity and composition of the incorporated graft products.     

Struktur und eigenschaften von ABS-polymeren. IX. Quantitative untersuchungen zur morphologie von ABS-polymerisaten

The technological properties of ABS polymers largely depend on the structure of the elastomer phase as well as on the elastomer/thermoplast interface. The morphological structure of such polymers can be determined from electron micrographs of ultramicrotome sections – after selective contrasting of the polybutadiene phase – or of replicas of fracture surfaces after selective chemical degradation. The various ABS polymers are classified by their manufacturing processes and their morphologies and characterized by electron micrographs. The degree and place of grafting are of particular importance. The quantitative determination of the surface- and internal grafting is achieved by combining the determination of the degree of grafting (extraction), the evaluation of the results obtained on particle counting, and a morphometric process. It is demonstrated that the morphometric process can in general be applied for the quantitative determination of the contrastable component in two-phase polymers.     

Eigenschaften von binären mischungen aus polyethylenen hoher dichte mit ultrahoher und normaler molmasse

The study is on two component blends of high density polyethylenes, having normal and ultra-high molecular weight. The polyethylenes were homogenized by two routes: in powder state or by rolling in melt, then pressed at temperatures in the range from 140°C to 220°C. Comparative studies showed that the way of homogenizing of the components does practically not affect the main mechanical properties of the blends when pressed at temperatures ≥ 160°C. Of special interest are the characteristics of those systems where ultra-high molecular weight polyethylene is the matrix component.     

Einfluss des polymerrückgrats auf eigenschaften von thermoplastischen elastomeren

4-Urazoyl benzoic acid groups were statistically attached to various hydrocarbon elestomers, polar elastomers and partially crystalline polymer via a polymer-analogous reaction. Thermal analysis (DSC), infrared spectroscopy (FT-IR), stress-strain experiments and dynamic-mechanical analysis were used to analyses whether these systems, analogous to functionalized polybutadienes, would form ordered supramolecular structures of the polar side-groups that would lead to a thermoreversible crosslinking. While the structure formation is suppressed for elastomers with a large cross-sectional area of the chain(e.g. butyl rubber) or polar side-groups (e.g. polychloroprene), the mechanical properties can be controlled by balancing supermolecular structure formation and crystallization in the case of polyoctenamer.     

Einfluß der struktur auf einige eigenschaften von polyurethan- und polyestermelamin-lacken

A method for calculating the crosslink density of systems originating from low molecular weight compounds is described. It is possible to determine quantitatively the influence of the crosslink density and the chemical composition on the glass transition temperature of network structures. This will be illustrated by crosslinked polyurethanes. On polyester melamine resins it will be shown that both the molecular weight of the polyester and the crosslink density of the network play an important role in the development of high solids coating systems as far as the solids content and the sagging are concerned.     

Herstellung und eigenschaften von cellulosebenzoat

Cellulose benzoates with degrees of substitution between 2.8 and 2.9 were synthesized in a one-step reaction of cellulose with benzoyl chloride in presence of pyridine as base. Their molecular weights were in the range 140000–100000; the glass transition temperature and the melting temperature were 155 and 274°C, respectively. The esters are readily soluble in organic solvents such as N,N-dimethyl formamide, chloroform and dichloromethane and show good thermal resistance up to 250°C. Because of the brittle character of cellulose benzoate, plasticizer (diethyl phthalate) must be added for the fabrication of films and workable, moulded parts. As shown by stress-strain and impact measurements, the hard and brittle character is retained for plasticizer contents up to 20 wt.-%.     

Einfluß von gleitmitteln auf die rheologischen eigenschaften von PVC-mischungen

The significance of lubricants is emphasized by the growing number of publications on this field. However, most of the authors compare the effect of the different lubricant types at the same concentration. But the rightness of this kind of comparison is questionable because the rheological characteristics of PVC compounds change sharply at the compatibility. Relatively little attention is paid to the processes taking place before the forming of the melt phase (powder blending) during PVC processing as well. From the results of the measurements made on a capillary viscosimeter and on a Brabender-plastograph the conclusion can be drawn that the comparison of lubricants is better in the same state (at the compatibility) than at the same concentration. The processes taking place in the mixing head of a Brabender-plastograph can be divided into three stages (powderblending, fusion, melt flow) and these are influenced differently by lubricants. The results of the measurements made on the capillary viscosimeter and the plastograph show a very good agreement in the melt flow state in view of lubricant effectivity.     

Untersuchung des Einflusses der Beanspruchungsgeschwindigkeit auf das Deformations‐ und Bruchverhalten von Weizenkörnern

Compression tests of deformation and fracture behavior of wheat grains were carried out at different loading rates that varied from 0.02 to 0.11 mm s^–1. The contact model originally developed for the spherical particles was adapted to describe the deformation and fracture behavior of elliptical wheat grains. The distributions of basic fracture parameters of wheat grains such as fracture force, fracture strength, fracture energy, and fracture displacement were fitted with normal distribution function.     

Synthese und eigenschaften von cycloaliphatischen glycidylestern

Diglycidylesters of cycloaliphatic dicarboxylic acids can be prepared in a good yield by the catalytic action of quarternary ammonium salts, or less universally also of thioethers. A considerable attention should then be especially paid to dehydrochloration. In comparison to epoxy resins from bisphenol A, it is an advantage of these products to have lower viscosity, higher reactivity with anhydrides, acids, and dicyandiamide, and excellent insulating properties, especially as far as are and track resistances are concerned. The best properties were found in diglycidylester of hexahydrophthalic acid, which are also less toxic. A disadvantage is a lower heat distortion point and a lower alkali resistance.     

Einfluß der herstellungsbedingungen auf E-modul und dichte von HD-polyethylen. II. Variation der kristallisationsgeschwindigkeit

Young's modulus and density of samples, made from high density polyethylene, have been measured. The samples were processed under pressure of 1 500 bar by means of nonisothermal and isothermal crystallization varying the rates of crystallization. All measurements have been carried out at ambient pressure and room temperature. Density is shown to decrease linearly with increasing logarithm of the rate of crystallization. Young's modulus is falling towards a minimal value with increasing rate of crystallization, but rising again at even higher rates. This rise being at variance with the wellknown decrease of the modulus with lower density (crystallinity) is explained by means of internal stresses of the samples. Consequences of thermodynamical and structural causes of the internal stresses are discussed.     

Einfluß der polymerisationsbedingungen auf die morphologie von schwefel-styrol-polymerisaten

For a polymer system sulfur-styrene containing 10 wt.-% styrene the morphologie depending on the polymerization temperature and time is described. Besides the characteristical orthorhombic phase a monoclinic and a pseudoorthorhombic phase were detected. Moreover amorphous material exists, depending on the polymerisation parameters.     

Struktur und eigenschaften von ABS-polymeren. III.. Charakterisierung der pfropfcopolymerisate von styrol-acrylnitril auf polybutadien durch oxydativen abbau

Graft copolymers of styrene-acrylonitrile on polybutadiene are isolated from the mixture with styrene-acrylonitrile copolymer formed during the graft copolymerization and are subjected to an oxidative degradation with potassium permanganate. The styrene-acrylonitrile copolymer grafted onto the polybutadiene can be isolated from the oxidation residue; it is, hence, accessible to further investigations. By blank runs it was verified that the styrene-acrylonitrile copolym er is not degraded under the oxidative conditions chosen. The increased content in carboxyl groups of the styrene-acrylonitrile copolymer isolated after oxidation of the polybutadiene grafted with it is attributed to fragments of the degraded graft basis.     

Struktur und mechanische eigenschaften von hochorientierten polymeren

Correlations between the structure and main mechanical properties of highly oriented linear and laminar polymer structures (fibres, films, needle crystals) are considered. To discuss structural conditionality of mechanical properties, different typical linear polymers having different molecular structure and values of intermolecular interactions are taken as, for example, polyethylene, polypropylene, polyvinyl alcohol, polyacrylonitrile, polyamides, polyesters, cellulose, aromatic polymers and laminar structures as, for example, graphite, boron nitride, silicon carbide. A number of physical and mechanical characteristics of fibres from the above polymers is compared with their structure. Calculation methods of strength and elastic properties of highly oriented polymer materials on the basis of their structural characteristics are given. Extreme mechanical properties of oriented polymer systems are fairly high. Theoretical strength values (at absolute zero temperature) for various polymers are from 600 to 13 000 kp/mm². On the basis of the data of temperature-time dependence of oriented polymers the ultimate strength values have been estimated, i. e. strength values of samples with the ideal structure a t a given temperature and time of destruction. These values are approximately from 1/3 to 4/5 of theoretical strength values (at room temperature and the time of destruction of 10 see). The values of ultimate elastic moduli of oriented linear polymers are up to 25 000 kp/mm², and more than 100 000 kp/mm² for laminar structures. The article summarizes experimental data about physical and mechanical properties of polymer monocrystals and practically obtained mechanical properties of man-made fibres. Relations between strength and elastic properties of oriented polymer substances have been also considered. Data on anisotropy of mechanical properties of oriented polymers as a function of anisotropy of their structure and heterodynamics of energy interactions are reported. Principal conditions determining the applicability of various polymers for preparing high modulus and super strong fibrous polymer materials have been analyzed.     

Struktur und eigenschaften von simultanvernetzten bismaleimidmodifizierten novolak-epoxidharzen

N,N′-4,4′-Diphenylmethane-bismaleimide (BMI) was oligomerized in semisolid phenolnovolak epoxide-resin (EP) up to P?_n = 10. The morphology of the novolakcured EP-BMI solid resins is a two-phase structure. It consists in a homogeneous EP-BMI phase of an interpenetrating polymer network (IPN) and a BMI phase. The dynamic-mechanical properties depend on the overall weight fraction w₂ of BMI and on the degree of oligomerization (P?)_n of BMI. The relative shear modulus of the EP-EMI resin in the rubber state shows that both phases can be coherent. The glass transition temperature (T_g) can be correlated with the degree of oligomerization of the BMI, for instance Δ P?_n ≡ 10 corresponds to Δ T_g ≡ 35 K and Δ w^x₂ ≡ 0,25 (weight fraction of BMI in the homogeneous EP-BMI phase). Surprisingly, the breaking strength remains constant.     

Darstellung und eigenschaften eines ionenaustauschers mit einem 1,3-diketon als Ankergruppe auf der Basis von Polystyrol

Aminopolystyrene is reacted with diketene to an exchanger with 1,3-diketone as anchor group. The capacity for Fe³⁺ ions is 3.2 mmol/g. The exchange comprises a fast and a slow step. The distribution coefficients for UO, Cu²⁺, Ni²⁺ and Fe³⁺ ions are presented as function of pH.     

Untersuchung und Modellierung der Aufwirbelung von auf Oberflächen abgelagerten Partikelschichten

The paper describes an experimental method to create reproducible particle layers. These layers are to be resuspended. The resuspension process itself is monitored coincidentally with an optical method. A theoretical approach to the phenomena uses a balance of forces effecting at a characteristic particle of the layer to estimate a resuspension coefficient. This coefficient describes resuspension in the way mass transfer coefficients describe mass transfer phenomena in fluids.