Modular Co-rotating Twin Screw Extruder Research Articles

목분-HDPE 복합체의 발연특성 분석

본 연구에서는 모듈라 회전 이축압출기를 통하여 제조한 목분-HDPE 복합체의 발연특성을 분석하기 위하여 콘칼로리미터 실험 및 연기밀도 실험을 실시하였다. 난연제 첨가에 따른 발연 저감효과를 살펴보기 위하여 인계, 멜라민계, 무기계 난연제 세 종류를 첨가한 복합체를 제조하여 동일한 실험을 통하여 비교 분석하였다. 콘칼로리미터 실험결과 총 연기발생율 및 총 연기발생량 모두 난연제를 첨가한 시편이 낮게 나타났다. 연기밀도 실험결과 난연제를 첨가한 복합체들의 초기 연기밀도 데이터 및 최대연기밀도 또한 낮게 나타났다. 그중 연기억제를 위해 가장 효과적인 난연제는 수산화마그네슘으로 나타났다. This paper is to analyze the smoke characteristics of wood flour-HDPE composites. The wood flour-HDPE composites were manufactured by modular co-rotating twin screw extruder. In order to analyze smoke characteristics, Cone calorimeter tests(by ISO 5660-2) and smoke density tests(by ASTM E 662) were performed. The specimens for these tests were differently made by adding flame retardants. The results of cone calorimeter test showed that adding flame retardants specimens are lower total smoke release, total smoke production than those of wood flour-HDPE composite. Also the results of smoke density test showed that adding flame retardants specimens are lower initial smoke data and maximum specific optical density than those of wood flour-HDPE composite. The most effective flame retardant is magnesium dihydroxide to decrease smoke characteristics.

목분-고밀도폴리에틸렌 복합체의 연소성 및 열적특성

본 연구에서는 목분-HDPE 복합체를 모듈라 회전 이축압출기를 이용하여 제조하여 연소성 및 열적특성을 평가하기 위하여 콘칼로리미터 실험및 열중량 분석실험을 실시하였다. 그리고 복합체의 난연성능 향상을 위하여 난연제(3종)를 첨가한 복합체의 화재성능을 평가하였다. 콘칼로리미터 실험 결과 난연제를 첨가하지 않은 복합체의 열방출률이 가장 높았으며 최대 열방출률 값은 <TEX>$446.6kW/m^2$</TEX>, 평균 열방출률 값은 <TEX>$185.5kW/m^2$</TEX>으로 가장 높게 나타났다. 열중량 분석 결과 난연제 첨가한 복합체들의 열분해가 먼저 시작되고 열 안정성을 향상시켰다. In this study, we were manufactured wood flour-HDPE composites by modular co-rotating twin screw extruder with L/D ratio of 42. We was measured cone calorimeter test and thermogravimetric analysis (TGA) to find the combustion characteristics and thermal properties for wood flour-HDPE composites. We then evaluated the effect of three additive-type flame retardants on fire resistance performance. The cone calorimeter test showed that the heat release rate (HRR) of untreated composites was the highest Peak HRR (<TEX>$446.6kW/m^2$</TEX>) as well as Mean HRR (<TEX>$185.5kW/m^2$</TEX>). From the TGA, it was shown that composites added flame retardants began early thermal decomposition and improved thermal stability.

The Morphology during Extrusion of PA6/PP Blends in the Presence of Nanoclays

The present study investigates the morphology of polyamide (PA6) and polypropylene (PP) blends in the presence of an organoclay during extrusion. Physical PA6 /PP blends and blends of PA6/PP and PP modified with maleic anhydride, both filled with a montmorillonite (MMT) modified alkyl ammonium organoclay, were prepared in a modular co-rotating twin screw extruder. Samples were collected along the extruder and analyzed by X-ray diffraction (XRD), oscillatory rheology, and scanning and transmission electron microscopy (SEM and TEM, respectively). Intercalation and some degree of clay exfoliation seem to have been achieved. Generally, the presence of the organoclay yields a finer dispersed phase along the extruder.

Experimental Investigation and Flow Modeling of Slippage Induced by Additives in Polyolefins in a Modular Co-rotating Twin Screw Extruder

Abstract Experimental and simulation studies of flow of a slipping polymer melt in a co-rotating twin screw extruder are presented. The experiments involve a wide range of polyolefins (polyethylene, isotactic polypropylene, isotactic polybutene-1, isotactic poly 4 methylpentene-1, and a cyclopolyolefin) with an octadecanoic acid additive. Mooney's capillary method is used to prove the occurrence and magnitude of slippage. In the twin screw extruder experiments, the die pressure is reduced for the compounds with octadecanoic acid compared to the neat polyolefins. Screw characteristic curves ( Q vs . dp dx ) were determined experimentally for both the polyolefin compounds and the neat polyolefins. These were found to be rather close. We modeled flow of a slipping non-Newtonian(power law) fluid in a screw channel and calculated screw characteristic curves. These were found to be close to our experimental observations.

Melting aspects of filled compounds in a modular co-rotating twin screw extruder

In the polymer industry, precompounded materials are widely used. Carefully designed melting experiments were carried out to investigate melting mechanisms in master batched polymer compounds, using an intermeshing co-rotating twin screw extruder. Calcium carbonate or aluminum powder was master batched with linear low-density polyethylene (LLDPE). The calcium carbonates, which were used in the compounds, have differences in weight fraction and particle size. The compounds containing filler have higher thermal conductivities and viscosities than neat polyethylene. We observed melting initiation and propagation mechanisms of LLDPE compounds by removal and characterization of polymer compound carcasses in the melting region. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1990–2012, 2006

Simulations of grafting monomers and associated degradation of polypropylene in a modular co-rotating twin screw extruder

Kinetic models of grafting maleic anhydride (MAH) and methyl methacrylate (MMA) on polypropylene (PP) were developed for screw extrusion. However, the kinetic models were insufficient to explain the grafting reactions along the length of modular co-rotating twin screw extruders because the rheological properties and the residence time of PP changed owing to degradation of PP during the grafting reaction. In order to model this system for a modular co-rotating twin screw extruder, the kinetic model of grafting reaction and models for degradation of PP were combined with fluid mechanics and heat transfer. Given the geometrical configurations of the screw, the operating conditions, and the physical properties of the polypropylene, the simulations predicted variation of molecular weight and mean residence time due to degradation of PP. The weight percent of grafted MAH or MMA on PP profiles along the screw axis was also calculated in the simulation. These predictions were compared with experimental data for various operating conditions. J. VINYL. ADDIT. TECHNOL. 11:143–149, 2005. © 2005 Society of Plastics Engineers.

On-line monitoring of the residence time distribution along a kneading block of a twin-screw extruder

An on-line Residence Time Distribution (RTD) measuring set-up that enables the characterisation of twin screw extruders at short axial increments is presented. It uses the light emission of a fluorescent tracer (perylene) to generate concentration versus time curves, which are then used to determine the usual RTD parameters, delay time, mean residence time and variance. The system is initially mounted on a rectangular die coupled to a single screw extruder, on-line and off-line measurements being directly contrasted. Then, the optical probe is positioned at several points along the axis of a modular co-rotating twin screw extruder, on-line and off-line data being again compared. Having gained confidence in the measuring technique, an experimental unit utilizing a transparent barrel is used to characterize the evolution of RTD along a kneading block of a twin screw extruder.

Engineering Analysis of Devolatilization of Various Additives in Intermeshing Co-rotating Twin Screw Extruders

Abstract An experimental study of devolatilization of nonane, xylene and 1-hexanol from molten polyethylene in a modular co-rotating twin screw extruder is described. Various modular screw designs, as well as different feed rates, screw speeds, and barrel temperatures were used. It was found possible to correlate the extent of devolatilization in different modular screw designs with a mass transfer coefficient which depends on screw speed and LDPE feed rate. The mass transfer coefficient depended on the liquid being devolatilized, being highest with 1-hexanol and lowest with nonane. In addition, the values of the mass transfer coefficient were obtained through experiments on the twin-screw extrusion of PE with nonane, xylene and hexanol. Interpretations of these results are described.

Investigation of Melting Phenomena in Modular Co-rotating Twin Screw Extrusion

Abstract An experimental investigation of the mechanisms of melting of polyolefins in a modular co-rotating twin screw extruder was carried out as a function of (i) barrel temperature including below the melting temperature (ii) screw speed and (iii) feed rate. The modular screws were removed from a twin screw extruder following experiments where pellets of linear low density polyethylene or isotactic polypropylene had been fed and processed under steady state conditions. The modular screws contained thermoplastic carcasses. These were sectioned and removed as well as inspected. Three melting initiation regimes were identified. These were (i) melting initiated from barrel, (ii) melting initiated from screw, and (iii) melting initiated in the bulk. At high barrel temperatures mechanism (i) is observed, at lower barrel temperatures and slower screw speeds mechanism (ii) is found, and at lower barrel temperatures and higher screw speeds mechanism (iii) is observed. The propagation of the melting process was also investigated. Pellet bed instabilities are usually involved at higher screw speeds. We discuss modeling of these mechanisms.

Twin screw extruder simulation programs - what can they offer?

Extrusion simulation software allows processors to scale-up from one extruder to another, predict processing problems and optimize screw design. The University of Akron's Institute of Polymer Engineering, directed by Dr. James L. White, recently released an updated, windows platform version of the personal computer-based Akro-Co-Twin Screw® extrusion simulation modeling program for intermeshing modular co-rotating twin screw extruders. Dr. White explains the advantages of the software to Plastics Additives & Compounding. Jennifer Markarian reports on this and other twin screw simulation programs including TXS from PolyTech, Ludovic from SCC and Sigma from the University of Paderborn.

DEVELOPMENT OF A GLOBAL COMPUTER SOFTWARE FOR MODULAR SELF-WIPING COROTATING TWIN SCREW EXTRUDERS

An analysis software for intermeshing modular corotating twin screw extruders was developed. A global computation model was incorporated in analysis software. The development of the composite model simulation of solids conveying, melting, and melt flow in a modular corotating twin screw extruder is described. We discuss the applications of simulation which predict axial fill factor, pressure, temperature, torque, power consumption, specific energy consumption, and average residence time. Design analyses for modular corotating twin screw extruders with multiple ports are presented for the various processing conditions. The results are compared for different size of machines. These computation results can assist the process-designing engineer in the optimization of an extruder design and operation parameters for various usage of machine.

Ninth of a Series Pioneer of the Modular Co-rotating Twin Screw Extruder–Rudolf Erdmenger (1911–1991)

Ninth of a Series Pioneer of the Modular Co-rotating Twin Screw Extruder–Rudolf Erdmenger (1911–1991)

Non-Isothermal Transient Startup of A Starved Flow Modular Co-Rotating Twin Screw Extruder

Abstract A model for non-isothermal Newtonian flow startup in an initially empty modular self-wiping co-rotating twin screw extruder is developed. A viscous Newtonian fluid is considered to gradually fill a modular co-rotating twin screw extruder with viscous heating and heat transfer to the barrel (and screw). The build up of the axial cup mixing temperature profiles with time was calculated for various modular screw configurations.

A comparative study of fiber breakage in compounding glass fiber‐reinforced thermoplastics in a buss kneader, modular Co‐rotating and counter‐rotating twin screw extruders

AbstractThe breakage of glass fibers was measured for several different types of continuous mixers including (i) Buss Kneader, (ii) modular intermeshing co‐rotating twin screw extruder, and (iii) modular intermeshing counter‐rotating twin screw extruder. Comparisons are made using different screw configurations, loadings, feeding ports, and mixing elements. Downstream feeding of glass fibers and milder screw configuration favor less breakage of glass fibers.

Modeling Flow and Fusion of Mixtures/Blends of Polymer Pellets and a Low Viscosity Phase in a Modular Co-rotating Twin Screw Extruder

Abstract A method of modeling the two phase flow and fusion process for a blend of low viscosity and high viscosity polymers in a modular intermeshing co-rotating twin screw extruder is presented. The delayed melting/fusing process in a large viscosity ratio system is simulated mathematically. Calculations were made for specific modular screw configurations. The screw configurations included both screw elements and kneading disk blocks. The temperature rise in a suspension of low viscosity melted and unmelted solid pellets was calculated along the screw axis. The suspension-blend transition temperature to a blend system was then determined. Furthermore, we tested the usefulness of this model by comparing the simulation with experimental results.

Continuous Polymerization and Copolymerization of Lauryl Lactam in a Modular Corotating Twin Screw Extruder

Abstract A study is presented of the polymerization of lauryl lactam and the copolymerization of lauryl lactam and caprolactam in a modular co-rotating twin screw extruder. Lauryl lactam had not been previously polymerized in a twin screw extruder. It was found possible to do this to high molecular weights. Generally, lower screw speeds result in longer residence times and higher conversions and molecular weights. The copolymers produced have broad melting transitions and their melting temperatures and heats of fusion exhibit minima as a function of comonomer composition.

Transesterification of Ethylene Acetate Copolymer in a Twin Screw Extruder

Abstract The chemical modification of poly(ethylene-co-vinyl acetate) with a primary aliphatic n-alcohol in a modular co-rotating twin screw extruder was investigated. The purpose was to build a theoretical model, able to predict the extent of conversion along the screw axis. First, the influence of operating conditions (throughput, screw speed, barrel temperature and initial reactant concentrations) on the EVA copolymer conversion was experimentally examined. Then, the extent of conversion was computed by coupling flow simulation and reaction kinetics. Theoretical and experimental results were found in good agreement, what allows the prediction of the reaction extent as a function of the processing conditions.

Continuous Mixing of Low Viscosity and High Viscosity Polymer Melts in a Modular Co-Rotating Twin Screw Extruder

Abstract Modular self-wiping co-rotating twin screw extruders have been widely used in polymer blending and compounding over the past four decades since they were first commercialized by Werner and Pfleiderer [1]. Despite its importance in the polymer processing industry, studies of the initial mixing process in a modular co-rotating twin screw extruder of binary polymer blends have received little attention until the last three years [2 to 9]. Among the various factors controlling the mixing of thermoplastic blends, the viscosity characteristics are a major determinant the degree of deformation of a disperse phase domain depends greatly upon the viscosity ratio. When one component of the mixing system has a very low viscosity, and there is an extremely large viscosity ratio, it is well known to be very difficult to mix [10 to 12].

A Composite Model for Solid Conveying, Melting, Pressure and Fill Factor Profiles in Modular Co -Rotating Twin Screw Extruders

Abstract A composite model simulation of solids conveying, melting and melt flow in a modular co-rotating twin screw extruder has been developed. This is based on combining existing melt conveying models with new melting and solids conveying models for the various elements of a modular twin screw extruder. Computations are made for axial fill factor, pressure, temperature, melting profiles and also the power consumption, torque, specific energy consumption and average residence times. The results are compared with experiment.

Thermal/Peroxide Induced Degradation and Maleation of Polypropylene by Reactive Extrusion

Abstract Experimental studies of three types of reactive extrusion are reported: thermal degradation, peroxide induced degradation and maleation of polypropylene for intermeshing modular co-rotating and counter-rotating twin screw extruder. The studies were carried out in a modular intermeshing twin screw extruder which can be co-rotating or counter-rotating and possesses different screw configurations. Generally thermal degradation was found to be more effective in intermeshing counter-rotating twin screw extruders when similar screw configurations and operating conditions are used. For peroxide induced degradation both counter-rotating and co-rotating machines performed about the same. For the maleation reaction the co-rotating twin screw extruder achieves higher conversions than the counter-rotating machine with all screw configurations and conditions studied. It would appear that the intermeshing counter-rotating twin screw extruder operates at a higher temperature and has poorer mixing characteristics than the co-rotating machine. Differences between the co-rotating and counter-rotating machines decrease with introduction of kneading disc blocks.