Single screw extruder method

Arastoopour, H., Single-screw extruder for soUd state shear extrusion pulverization and method, US patent, 5,704,555, 1998. 

Elucidation of degradation kinetics for the reactive extrusion of polypropylene is constrained by the lack of kinetic data at times less than the minimum residence time in the extruder. The objectives of this work were to develop an experimental technique which could provide samples for short reaction times and to further develop a previously published kinetic model. Two experimental methods were examined the classical "ampoule technique" used for polymerization kinetics and a new method based upon reaction in a static mixer attached to a single screw extruder. The "ampoule technique was found to have too many practical limitations. The "static mixer method" also has some difficult aspects but did provide samples at a reaction time of 18.6 s and is potentially capable of supplying samples at lower times with high reproducibility. Kinetic model improvements were implemented to remove an artificial high molecular weight tail which appeared at high initiator concentrations and to reduce step size sensitivity. 

Single Screw Extruder Devolatilization Using Latinen s Model Review the paper by Biesenberger and Kessidis and discuss (a) the experimental method used... 

There are different approaches for 2-dimensional modeling. One observation method relates to boundary layers, for example, in order to determine temperature peaks in the extruder [3]. Before the computer age, numerous process models for single screw extruders but also for twin extruders were developed [4]. 

This interaction depends on stock temperature and in turn on the performance of PVC melts. Flexible PVC is normally calendered at temperatures of 10 to 20C (50 to 68F) lower than rigid PVC. In flexible PVC production, a short single screw extruder acting as a strainer filters out contaminants from stock before reaching the calender. This important method is not applicable to rigid PVC because it drastically increases the head pressure and the consequent overheating would cause the stock to decompose. 

Besides the polymerization method, a method of directly mixing nylon polymers and organophUic clay using a twin screw extruder was developed. Although clay mineral is not dispersed sufficiently using a single screw extruder (screw speed 40 rpm, barrel temperatme 240 °C), it can be weU-dispersed using a twin screw extruder (screw speed 180 rpm, barrel temperature 240 °C). Experimental results and mechanical characteristics have been re-... 

The composition of recycled HDPE/virgin PP blends prepared in a single-screw extruder was monitored inline at three different points by near-infrared spectroscopy. The data were interpreted by simple and multiple linear regression and multivariate methods. 5 refs. 

Many standard methods are used to devolatilize materials. Flash devolatilizer or falling strand devolatilizer are synonyms of equipment in which the falling melt is kept below the saturation pressme of volatiles. Styrene-acrylonitrile copolymers devolatilized in flash devolatilizer had a final concentration of ethylbenzene of 0.04-0.06. Devolatilization of LLDPE in a single-screw extruder leaves 100 ppm of hydrocarbon solvent. 500 ppm chlorobenzene remains in similarly extruded polycarbonate. It is estimated that if the polymer contains initially 1-2% solvent, 50-70% of that solvent will be removed through the vacuum port of an extruder. These data seem to corroborate the information included in the above... 

Although extrusion is by far the most common processing method for WPC, the processors use a variety of extruder types and processing strategies [89]. Some processors run compounded pellets through single-screw extruders to form the final shape, others compound and extrude final shapes in one step using twin-screw extruders. 

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