Functionalization of wood particles through a reactive extrusion process

Wood particles were modified in a reactive extrusion process with maleated polyethylene (MAPE) and maleated polypropylene (MAPP) compounds. Contents of MAPE were varied to study the effect of material composition on grafting efficiency during reactive extrusion, while extruder barrel temperatures and rotational screw speeds were varied to evaluate the effects of processing conditions on the modification of wood particles. Polymer molecular weight effects were followed using MAPP, with different molecular weights. Efficiency of the modification was assessed using FTIR and XPS surface analysis techniques, along with a titrimetric analysis, to verify the esterification reaction between the wood particles and maleated polyolefins. The grafting of maleated polyolefins onto the surface of the wood particles through a reaction of the hydroxyl groups on the wood surface with the maleated groups of the maleated polyolefins was confirmed, while the level of grafting of MAPE onto wood particles was determined to be a function of the MAPE concentration. However, there was no significant difference found in grafting efficiency at different extrusion processing conditions, rather all of the conditions resulted in adequate grafting. Similarly, there was no difference in grafting efficiency with the molecular weight of MAPP. Reactive extrusion was found to be a suitable technique for the modification of wood particles, with maleated polyolefins, for all of the material compositions and processing conditions studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3131–3142, 2006     

Starch‐graft copolymers of N‐vinylformamide and acrylamide modified with montmorillonite manufactured by reactive extrusion

Graft copolymers of potato starch with acrylamide, acrylamide, and acrylic acid or N‐vinylformamide in the presence of 1–16 wt % montmorillonite were manufactured via reactive extrusion. XRD and TEM measurements exhibited intercalated structure of clay dispersion (d001 distance up to 2.3 nm). The influence of graft polymer(s) system and montmorillonite content on thermal properties, water sorption as well as polyvalent metal cation (Cd²⁺ and Fe³⁺) sorption of obtained starch graft copolymers has been determined. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

尼龙6的双螺杆反应挤出工艺

介绍了国内尼龙 6的双螺杆反应挤出工艺。通过己内酰胺阴离子型快速聚合 ,直接反应成型制取高性能尼龙 6 ,具有生产连续 ,周期短 ,产品性能好的优点。反应挤出生产的尼龙 6相对粘度可达 4 2～ 5 0 ,拉伸强度、弯曲强度、缺口冲击等性能均优于传统工艺生产的尼龙 6。对双螺杆反应挤出机的工艺要求及特点作了简介。     

通过反应挤出对聚碳酸酯进行扩链

采用反应挤出机(缩聚型)研究了聚碳酸酯(PC)在熔融挤出过程中在各种添加剂作用下的扩链反应。结果表明:降低螺杆转速和提高挤出机反应段的温度有利于提高产物的特性黏数([η]);加入均苯四甲酸二酐、双(?)唑啉、苯乙烯-马来酸酐共聚物、无机氧化物、钛酸四丁酯等对产物的[η]提高不大;加入过氧化物对PC的扩链有一定的作用;加入高黏型的聚对苯二甲酸丁二酯(PBT)使产物的[η]显著提高,w(PBT)为50%时,由纯PC的0.361 dL/g提高至0.695 dL/g。     

Controller design and performance analysis for a reactive extrusion process

This paper presents the design and analysis of a process control strategy for a reactive extrusion polypropylene degradation process. The primary control objective is to continuously produce polypropylene with desired properties (viscosity) despite variations in the properties of the feed material. The viscosity of the polypropylene, measured using an In-line Wedge Rheometer, is controlled by manipulating the feed concentration of the peroxide which acts as the initiator for the degradation reaction. An empirical model of the reactive degradation process is developed which describes the process dynamics and the characteristic process disturbances. Minimum variance (MV), constrained minimum variance (CMV), and pole placement (PP) controllers are first evaluated and compared in simulation. Then, a pole placement controller is implemented on the actual reactive extrusion process, with results being presented for the response of the controlled process to load disturbances due to feed material changes.     

Alder Ene functionalization of polypropylene through reactive extrusion

A commercial isotactic polypropylene was degraded to increase its terminal vinylidene group concentration, and it was subsequently functionalized with maleic anhydride through the Alder Ene reaction at temperatures above 200°C in a co‐rotating twin screw extruder. Characterization of the maleated product by Fourier transform infrared spectroscopy, ¹H NMR, differential scanning calorimetry, and gel permeation chromatography showed the anhydride group to be terminally attached, and the degree of functionalization was determined by infrared analysis. Increased temperature and maleic anhydride concentration, as well as improved mixing in the extruder, were found to improve the extent of the reaction. The catalytic contribution of Lewis acid species was evaluated, and ruthenium chloride was found to increase the extent of the reaction by 16% in comparison with stannous chloride as a catalyst in the Alder Ene reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 503–516, 1999     

A study on the reactive extrusion process of polyurethane

An engineering analysis of the reactive extrusion process of a thermoplastic polyurethane was made through numerical simulation and actual experiment. The reactants used in this system were 4,4′diphenylmethane diisocyanate, polycaprolactone diol (M.W., 824), and 1,4-bu-tanediol with equivalent weight ratio of 2:1:1. As a catalyst, dibutyltin dilaurate was used. The reaction kinetics and the viscosity function were obtained through experiments, and the mathematical model which includes the conservation equations of mass, momentum, energy, and chemical species was solved numerically to obtain the velocity, concentration, temperature, viscosity, and pressure profiles. The actual experiments were performed in the laboratory scale extruder to compare the experimental results with those of the numerical simulation.     

Hybrid materials derived from modified styrene-butadiene-styrene copolymer (SBS) and silica through the sol-gel process

Non-bonded and covalently bonded organic-inorganic hybrids materials, SBS-NO₂/SiO₂, SBS-NH₂/SiO₂ and SBS-Si(OCH₃)₃/SiO₂, were prepared by the sol-gel process using tetraethoxysilane (TEOS) in presence of modified SBS, SBS-NO₂, SBS-NH₂ and SBS-Si(OCH₃)₃, respectively, with HCl as a catalyst. The modified SBS was prepared without damage its molecular weight and chemical structure, which was identified by the means of FTIR spectroscopy, elementary analysis, and Wijs titration. The interfacial force and the properties such as hemical resistance, elongation, thermal stability, and dynamic mechanical properties of the hybrids were investigated in detail.     

Formation of a polyetheramide triblock copolymer by reactive extrusion; process and properties

The synthesis of polyetheramide, containing poly(tetramethylene ether) (PTMEG) as the soft segment phase and polylactams as the hard phase was carried out in a Leistritz modular intermeshing counter‐rotating twin‐screw extruder in a one‐step, solvent‐free process. No by‐product such as carbon dioxide or H²O is formed during the reaction procedure. Isocyanate‐terminated telechelic PTMEG was premixed with caprolactam, and these were fed into the twin‐screw extruder to form the polyetheramide triblock copolymer. This triblock copolymer has not been previously polymerized in a twin‐screw extruder or continuous mixer. Subsequent to polymerization, the copolymer and PA6 homopolymer were also melt‐spun into fibers. Molecular weights and molecular weight distributions were determined by GPC on trifluroacetylated samples. Thermal, rheological, mechanical, and structural properties were investigated. It appears that phase separation (arising from immiscibility between the polyether segment and the polyamide segment as the reaction proceeds) did not hinder the chemical reaction between the two reactants because of the intense mixing in the twin‐screw extruder. The new triblock copolymer should have application as a rubber‐toughened thermoplastic or thermoplastic elastomer depending upon the elastomer content.     

Efforts to decrease crosslinking extent of polyethylene in a reactive extrusion grafting process

Grafting of acrylic acid and glycidyl methacrylate onto low density polyethylene (LDPE) was performed by using a corotating twin‐screw extruder. The effects of residence time and concentration of initiator and monomers on degree of grafting and gel content of grafting LDPE were studied systematically. Paraffin, styrene, p‐benzoquinone, triphenyl phosphite, tetrachloromethane, and oleic acid were added to try to decrease the extent of crosslinking of LDPE. 4‐hydroxyl‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy (4‐hydroxyl‐TEMPO) and dipentamethylenethiuram tetrasulfide were also tried to inhibit crosslinking reaction of LDPE during its extruding grafting process. It was found that p‐benzoquinone, triphenyl phosphite and tetrachloromethane were good inhibitors for crosslinking of LDPE. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 535–543, 2001     

Mechanical behaviour modelling of a nanostructured polyamide blends obtained by reactive extrusion process

The aim of the present work was to study the effect of the composition and operating conditions on the properties of nanostructured polyamide blends obtained by reactive extrusion. The ultimate objective consisted in optimizing the high impact energy of these materials using an experimental design based on the D-optimality and rotatability criteria. A thermodynamic approach of relaxation phenomena called distribution of nonlinear relaxations (DNLR) was proposed to account for the nonlinear mechanical behaviour of the obtained polyamide blends for different compositions and extrusion conditions. Five parameters of the DNLR law have thus been modelled as functions of these operating conditions using quadratic polynomial relations.The accuracy of this modelling was evaluated by establishing some comparison between the experimental data and the predictive results and by performing statistical tests.     

Recycled poly(ethylene terephthalate) chain extension by a reactive extrusion process

A commercial‐scale reactive extrusion processing system for recycled poly(ethylene terephthalate) (PET) flakes with an added chain extender, pyromellitic dianhydride (PMDA), was investigated. The PMDA concentration was varied with the intention of reaching a higher recycled PET intrinsic viscosity ([η]). The effect of changing the extruder residence time on the system's stability and the recycled PET [η] was also investigated. Reactive extruded PET with a PMDA concentration up to 0.3 wt% was found to have a higher [η] and lower carboxyl content than recycled PET processed in a normal extrusion system. A shift in [η] of about 0.18 dl/g was obtained with a 0.3 wt% PMDA concentration. A PMDA concentration above 0.3 wt% produced chemical, thermal and hydrodynamic instability in the system, causing crosslinking reactions and gel formation. The reactive extrusion system was stable at low residence time (45 s) and moderate (0.15 wt%) PMDA concentration; however, using 0.2 wt% PMDA produced higher reactive extruded recycled PET [η] with lower carboxyl content than other PMDA concentration levels examined. Residence times higher than 45 s produced higher reactive extruded recycled PET [η]. Reactive extruded recycled PET was also tested for mechanical properties. Polym. Eng. Sci. 44:1579–1587, 2004. © 2004 Society of Plastics Engineers.     

Modification of wood flour/PLA composites by reactive extrusion with maleic anhydride

MA modified wood flour/PLA composites were prepared by one‐step reactive extrusion, in which wood flour and poly(lactic acid) (PLA) were used as raw material, maleic anhydride (MA) was used as modifier, and dicumyl peroxide (DCP) was used as initiator. The influences of MA concentration on the morphology, thermal stability, rheological, and mechanical properties of the composites were studied. The addition of MA improved the compatibility of the composites significantly. The thermal and rheological results showed that with the increase of the concentration of MA, the thermal stability of the composites decreased, the storage modulus and complex viscosity of the composites also decreased. The MA modified composites had an enhanced mechanical strength compared to the unmodified one. As the concentration of the MA increased, the tensile and flexural strength of the composites first increased and then decreased, and reached a maximum when the concentration of MA was 1 wt %. The MA modified composites showed a better water resistance than the unmodified ones. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43295.     

阴离子聚合反应挤出过程的化学热效应

为定量分析聚合反应倾向、优化反应加工条件,在建立紧密啮合同向旋转双螺杆挤出机的反应器模型及物料的化学反应动力学模型、化学流变模型的基础上,分析了阴离子聚合反应挤出过程的化学热效应,推导出反应热的释放量与反应热强度的数值计算式,并通过算例展示了其变化特点。     

Residence time and conversion in the extrusion of chemically reactive materials

Twin‐screw extruders offer improved control of the residence time distribution (RTD) and mixing in materials such as plastics, rubber and food. Based on the flow and the heat transfer characteristics obtained for a self‐wiping, co‐rotating twinscrew extruder, the residence time and chemical reaction are studied by tracking the particles. For normally starve‐fed twin‐screw extruders, the length of the completely filled section is calculated as function of the process variables using the coupling of the flow with the die. With a model of the solid conveying section, the RTD for the whole extruder is calculated for corn meal at different screw speeds and flow rates. The calculated variation of RTD with the screw speed and the flow rate yields good agreement with observations from many experiments. The variation of the fully filled section length, chemical conversion and mixing effectiveness are also obtained under different operation conditions. Most of the results are in qualitative agreement with experimental results and may be used as guidelines for extruder design and determination of optimal operating conditions.     

Numerical analysis of a reactive extrusion process. Part II: Simulations and verifications for the twin screw extrusion

A newly designed extruder reactor for grafting vinyl monomers onto polyolefins was studied experimentally and theoretically. The process was made up of a self‐wiping co‐rotating twin screw extruder with a separated reaction zone and two vent zones. The reactive extrusion was performed using a linear low density polyethylene, vinyltrimethoxysilane and di‐t‐butylperoxide under different operation conditions. For the purpose of process analysis, we built a computer simulation based on the reaction kinetics and rheological models studied in the preceding paper. The flow field in the extruder was calculated by the flow analysis network (FAN) method with non‐isothermal non‐Newtonian flow conditions. The iterative procedure was organized to predict local pressure, filling factor, cumulative residence time and temperature along the extruder. Furthermore, we succeeded in representing the profiles of reaction conversion and shear viscosity. Calculated results showed good agreements with the experimental data.     

Preparation and characterisation of wood flour/polystyrene composites by subcritical fluid-assisted reactive extrusion

ABSTRACT

In this work, subcritical fluids are applied to twin-screw extruders as a novel design for the preparation of wood flour/polystyrene composites. Subcritical fluids have suitable process conditions, excellent swellability and diffusibility. Therefore, the subcritical fluids in the extruder system can alleviate the thermal degradation of wood floor, reduce the viscosity of the resin and strengthen the mass transfer rate. Wood flour evenly distributed in the polystyrene matrix in the presence of subcritical n-propanol. The best adhesion between wood flour and PS is shown when 10?wt-% MAPS is added. MAPS was confirmed to be grafted onto wood flour. In addition, the thermal stability and crystallinity of wood flour and the composites are studied. Mechanical tests proved the effectiveness of subcritical fluids, particularly subcritical n-propanol, in improving the mechanical properties of the composites. The extrusion temperature and content of MAPS show optimum values at 190°C and 10%, respectively.     

Biodegradable soy protein–polyester blends by reactive extrusion process

Blends of soy protein concentrate and biodegradable polyester (Eastar Bio Copolyester, EPE) were prepared by using glycerol as a compatibilizing agent. Good miscibility was obtained only when the soy protein was initially combined with glycerol under high shear and at elevated temperatures in an extruder. Under these conditions, partial denaturing of the soy protein led to specific interactions between functional groups of the protein with the glycerol. The extrusion conditions and appropriate screw configuration were the critical factors affecting the reactivity of the protein and hence, the properties of the blends. Screws with large kneading blocks that produced high shear mixing were preferred and led to thermoplastic blends characterized by high elongation and high tensile strength. The morphology of these soy protein/polyester blends was studied by using environmental scanning electron microscopy (ESEM) and indicated good wetting of the soy protein particles within the polyester matrix. The thermal properties were studied by differential scanning calorimetry (DSC) and showed a lower degree of crystallinity and a continuous depression of the melting point of the polyester as the concentration of protein was increased. The possibility of using soy protein concentrate instead of the more expensive (higher purity) soy protein isolate in the preparation of biodegradable resins should lead to new commercial opportunities based on renewable, agricultural byproducts. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3231–3239, 2004     

振动力场强化聚合物反应挤出过程的研究

介绍了将电磁场引起的机械振动力场引入聚合物反应挤出过程的作用和基本作用原理。引入振动力场可以对挤出机内的物理和化学反应产生积极影响，改善聚合物熔体的粘弹性，提高聚合物混炼和动态硫化效果。该方法可用于提高动态硫化EPDM／PP热塑性弹性体的质量。     

纳米材料改性抗菌水性木器涂料的开发

介绍了纳米抗菌水性木器涂料的开发过程和施工工艺,分析讨论了其中的技术和问题。