Search results for "Polyoxymethylene"

Experimental studies on uniaxial and echibiaxial tensile tests applied to plastic materials sheets

2019

Abstract The main objective of this paper is to determine the behavior of few plastic materials using two different type of tests. We use classical uniaxial tensile test to determine the most important mechanical and elastic characteristics, such as: yield stress, Young modulus, tangent modulus, maximum stress and maximum strain and to plot engineering stress vs. engineering strain curve for these materials. The second test, that was used in this study, was echibiaxial tensile test on the spherical punch. This test was used to determine maximum breaking force and, of course maximum displacement of specimen on punch direction and others few important characteristics, such as: major and minor…

Amorphous hydrogenated carbon (a-C:H) depositions on polyoxymethylene: Substrate influence on the characteristics of the developing coatings

2016

Abstract After oxygen plasma treatment polyoxymethylene (POM) material was exposed to acetylene plasma to progressively deposit two different types of amorphous hydrogenated carbon (a-C:H) films. Radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) was used to generate both plasma processes. The surface morphology of the coated samples has been investigated by atomic force microscopy (AFM) and their chemical composition by Diffusive Reflectance Infrared Fourier Transform (DRIFT) and Raman spectroscopy. Results revealed the absence of a solid interlayer formation between the a-C:H films and POM. The in sequence exposure of oxygen and acetylene plasma on POM substrate prevents…

Evolution of the sp2 content and revealed multilayer growth of amorphous hydrogenated carbon (a-C:H) films on selected thermoplastic materials

2017

Amorphous hydrogenated carbon (a-C:H) films were gradually deposited on high-density polyethylene (HDPE), polyethylene terephthalate (PET) and polyoxymethylene (POM) via an indirect (f-type) and a direct (r-type) plasma-enhanced chemical vapor deposition (PECVD) process with acetylene plasma. The surface morphologies of the thicker r-depositions on the three different thermoplastics have been analyzed by atomic force microscopy (AFM) at varying micrometer scales. Absorbance spectroscopy has been used to characterize the optical properties of all coatings. Intrinsic stress release phenomena are revealed on thicker layers through the detection of characteristic surface corrugations. Based on …

Aging of Nanosized ZnO Modified Polyoxymethylene Blends with Ethylene–octene Copolymer

2015

The influence of ethylene–octene copolymer and zinc oxide (ZnO) on structure and tensile stress–strain behavior of polyoxymethylene were investigated before and after ultraviolet weathering. Addition of ZnO considerably improved stress–strain characteristics of the ultraviolet-irradiation impaired composites. Crystallinities of ultraviolet-irradiated composites were affected by numerous competitive processes, including suppression of crystallization in the presence of multiple components in the system, nucleation induced by nanofiller, secondary crystallization and amorphization because of the chain scissions of the macromolecules. Addition of ZnO considerably improved stability of the comp…

Growth of polyoxymethylene crystals during cationic polymerization of trioxane in nitrobenzene

1973

Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options.

2018

‘Capable-of-being-shaped’ synthetic compounds are prevailing today over horn, bone, leather, wood, stone, metal, glass, or ceramic in products that were previously left to natural materials. Plastic is, in fact, economical, simple, adaptable, and waterproof. Also, it is durable and resilient to natural degradation (although microbial species capable of degrading plastics do exist). In becoming a waste, plastic accumulation adversely affects ecosystems. The majority of plastic debris pollutes waters, accumulating in oceans. And, the behaviour and the quantity of plastic, which has become waste, are rather well documented in the water, in fact. This review collects existing information on pla…

Kinetische Untersuchungen über die kationische Polymerisation von wasserfreiem Formaldehyd. 40. Mitt. Über polyoxymethylene

1971

Die Polymerisation von Formaldehyd in atherischer Losung bei −78°C mit SnCl4 und HClO4 als Initiatoren wurde untersucht. Die Konzentration der aktiven Zentren (Polyoxymethylen-Kationen) wurde bestimmt, indem die Polymerisationen durch Zugabe eines grosen Uberschusses an n-Amylalkohol abgebrochen und die entstandenen Pentoxylendgruppen nach Reinigung und Hydrolyse der Polymeren gaschromatographisch bestimmt wurden. Die Initiierung der Polymerisationerfolgt rasch und fuhrt zu vollstandigem Umsatz des Initiators wahrend der ersten Minuten. Unter gunstigen Reaktionsbedingungen ergibt jedes eingesetzte Initiatormolekul ein Polyoxymethylene-Kation. Ein kinetischer Abbruch wurde nicht festgestellt…

Modification of polyoxymethylene for increased thermal resistance

2017

Ternary nanocomposites, composed of polyoxymethylene (POM), ethylene octene copolymer and zinc oxide (ZnO), are prepared by melt compounding. The effects of two types of ethylene-octene copolymers, differing with α-octene content (38% for EOC38 and 17% for EOC17), as well as nanostructured ZnO on thermal behavior of POM are investigated. The content of EOC in the POM based composites is varied between 10 and 50 wt%, while the content of ZnO is 2 wt%. Thermal behavior of POM based systems are studied by using differential scanning calorimetry and thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. Results of thermogravimetric analysis show that, by rising either …

Über die polymerisation bei der sublimation des trioxans. 17. Mitt. Über polyoxymethylene

1962

Bei der Sublimation von gereinigtem Trioxan und bei seiner Kristallisation aus der Schmelze erfolgt in der kristallinen Phase eine langsame Polymerisation zu hochmolekularem Polyoxymethylen. Die Ausbeuten an Polymeren sind um so hoher, je trockener das Trioxan ist und je geringer der Fremdgasdruck bei der Sublimation ist. Es wurde festgestellt, das diese Polymerisation durch Spuren von monomerem Formaldehyd ausgelost wird; wenn letzterer durch Silberoxyd zerstort wird, kann Trioxan unverandert sublimiert und kristallisiert werden. Wahrend der Polymerisation wird monomerer Formaldehyd von den wachsenden Polyoxymethylenketten abgespalten und so der Polymerisationskatalysator regeneriert. Desh…

Über die möglichkeit der bildung makrocyclischer polyoxyniethylene. 29. mitt über polyoxymethylene1

1966

Bei der kationischen Polymerisation von 1,3,5-Trioxan in Cyclohexan entstehen Polyoxymethylene, welche partiell thermisch stabil und alkalibestandig sind, ohne das irgendwelche bekamiten stabilen Endgruppen nachgewiesen werden konnten. Moglicberweise handelt es sich hierbei um Makrocyclen. Cationic polymerization of 1,3,5-trioxan in cyclohexane yields polyoxymethylene which is partially stable to heat and to alkali but does not contain any of the known stable endgroups. These polymers possibly have a macrocyclic structure.