反应降解聚丙烯的高速挤出流动稳定性

采用双毛细管流变仪研究了反应降解聚丙烯试样的挤出稳定性。结果表明:基础树脂聚丙烯PP-2401的挤出压力随剪切速率增高呈阶梯状稳定增高,而降解聚丙烯的挤出压力随剪切速率增高出现不规则波动;低相对分子质量降解聚丙烯的压力波动主要发生在口模入口区;发生波动的原因与聚丙烯分子链结构特征有关,同时与熔体在口模区的Weissenberg准数和Reynolds准数较大有关。     

Characterization of polyamide 6 made by reactive extrusion. I. Synthesis and characterization of properties

The anionic polymerisation of ε-caprolactam in a corotating, intermeshing twin-screw extruder is discussed in terms of the materials formulation, extruder screw profile, and processing parameters such as temperature and screw speed. Using a variety of analytical characterization techniques, it is demonstrated that molecular mass, residual monomer content, and mechanical properties of the polyamide 6 are very sensitive to the reactive processing conditions employed. © 1994 John Wiley & Sons, Inc.     

In situ formation and compounding of polyamide 12 by reactive extrusion

The anionic polymerization of lauryllactam was initiated at 270°C using sodium hydride as an initiator and N,N′‐ethylene‐bisstearamide (EBS) as an activator (NaH:EBS molar ratio of 2). Polymerization occurred in less than 2 min and was successfully performed in an internal mixer and a twin‐screw extruder with corotating intermeshing screws (Werner & Pfleiderer ZSK 25). The content of residual monomer, as determined by thermogravimetric analysis, was lower than 0.5 wt %. Molecular weight, as measured by size exclusion chromatography, was governed by the lauryllactam:NaH molar ratio calculated on a M_n of 25 kg/mol at a constant NaH:EBS molar ratio of 2. Blends were prepared in situ by polymerization of lauryllactam solutions of various polymers. When poly(ethylene‐co‐butylacrylate) (Lotryl®; Atofina) was dissolved in lauryllactam, rubber‐toughened polyamide 12 blends were obtained. Mechanical properties of the injection‐molded polymers were examined by stress–strain as well as notched Charpy impact tests at different temperatures. Blend morphologies were imaged by scanning electron microscopy (SEM). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 344–351, 2003     

Characterization of low molecular weight carboxyl-terminated polyamides obtained by reactive extrusion of polyamide 6 with trimellitic anhydride

Reactive extrusion has been applied as a very effective and fast process for controlled chemical degradation of a commercial polyamide 6 with trimellitic anhydride in the melt. A reaction mechanism based mainly on the amide/anhydride reaction has been discussed and confirmed by measurements of the solution viscosity, end group analysis, SEC, NMR, and IR spectroscopy. The systematic loss of molecular weight of the polyamides resulting from PA chain repture and the formation of imide linkages and carboxyl end groups were investigated. The theoretical values of molecular weight and end group concentration of the obtained oligoamides predicted by the reaction mechanism are in good agreement with the experimental ones. © 1996 John Wiley & Sons, Inc.     

Starch-derived glycol and glycerol glucosides prepared by reactive extrusion processing

Previously, starch-derived glycol and glycerol glucosides were prepared by batch-reaction processes and had excellent potential as chemical intermediates for a wide range of products. However, more efficient processes for preparation of these derivatives are needed. In this present work, a modern corotating, intermeshing, twin-screw extruder with a barrel length/screw diameter (L/D) ratio of 43: 1 was used to study the reaction of starch with ethylene glycol and glycerol in the presence of sulfuric acid catalyst at elevated temperatures. A fully continuous process was used. Variables that were investigated included temperature (140–180°C), glycol or glycerol/starch AGU mol ratio (1.5–4.0), starch feed rate (5–30 lb/h), screw speed (100–475 rpm), residence time, specific energy, and several types of commercial cornstarch and corn flour products. Rates and extents of reaction that occurred in the barrel were determined by analyzing samples that were quenched just prior to extrusion. The major glucosides were quentitated by high-performance liquid chromatography. Results of this study show that starch can be continuously, rapidly, and efficiently converted to glucosides in 90% yield at high production rates. Such processing is expected to be technically feasible for the reaction of a wide range of polyhydroxy alcohols with various starch substrates.     

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.     

Clay distribution and crystalline structure evolution in polyamide 6/montmorillonite composites prepared by activated anionic polymerization

Nanostructured polymer composites (NPC) based on polyamide 6 (PA6) are prepared by activated anionic ring‐opening polymerization (AAROP) of mixtures of ε‐caprolactam (ECL) and organically treated montmorillonite (o‐MMT). The polymerization is performed in bulk, at 165°C, i.e., below the melting point of the resulting APA6, the reaction time being in the range of 10–15 min. The o‐MMT content is varied in the 0.5–10% range. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) show that exfoliated NPC can be produced with clay loads of 0.5–1.0%. Larger clay amounts lead to various degrees of intercalation of the MMT layers. FT‐IR imaging proves that all NPCs contain MMT aggregates with sizes in the 10–20 µm range. The formation of the matrix crystalline structure is followed directly by performing AAROP of an activated ECL/o‐MMT blend in a synchrotron beamline. Irrespective of the o‐MMT type and concentration, it is the α‐PA6 that forms first and in larger amounts. The γ‐PA6 polymorph can be found in predominating amounts only after melting and recrystallization of the already produced polymer matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1228‐1238, 2013     

反应挤出制备聚三氟丙基甲基硅氧烷的微观结构及性能

采用反应挤出技术,将三氟丙基三甲基环三硅氧烷在双螺杆挤出机中进行负离子开环聚合制备了聚三氟丙基甲基硅氧烷(PMTFPS)橡胶,通过凝胶渗透色谱、傅里叶变换红外光谱、核磁共振氢谱表征了PMTFPS,并研究了PMTFPS的耐热性能及其硫化胶的耐老化性能和耐油性能。结果表明,制得的PMTFPS主要是以三氟丙基甲基硅氧为重复单元、数均分子量为41×104、分子量分布指数为1.33的氟硅聚合物,且具有良好的耐热性能;PMTFPS硫化胶在150℃下表现出良好的耐老化性能,同时对煤油、柴油和机油具有一定的耐受性,从优到劣依次为机油,柴油,煤油。     

Tough polyamide 6/core–shell blends prepared via in situ anionic polymerization of ε‐caprolactam by reactive extrusion

In this study, the molten ε‐caprolactam (CL) solution of maleated styrene‐ethylene/butylene‐styrene block copolymer (SEBS‐g‐MA) and polystyrene (PS) containing catalyst and activator were introduced into a twin screw extruder, and polyamide 6 (PA6)/SEBS/PS blends were successfully prepared via anionic polymerization of CL by reactive extrusion. The mechanical properties measurements indicated that both the elongation at break and notched Izod impact strength of PA6/SEBS/PS (85/10/5) blends were improved distinctly with slight loss of tensile and flexural strength as compared to that of pure PA6. The images of transmission electron microscopy showed that a core–shell structure with PS core and poly (ethene‐co‐1‐butene) (PEB) shell was formed within the PA6 matrix. Fourier transform infrared was used to investigate the formation mechanisms of the core–shell structure. POLYM. ENG. SCI., 53:2705–2710, 2013. © 2013 Society of Plastics Engineers     

Rheology and thermal behavior of long branching polypropylene prepared by reactive extrusion

Long‐chain branching polypropylene (LCB‐PP) was achieved by reactive extrusion in the presence of bifunctional monomer [1,6‐hexanediol diarylate (HDDA)] and peroxide of dicumyl peroxide (DCP). Influences of HDDA and DCP concentrations on the branching efficiency were comparatively evaluated. Fourier transformed infrared spectroscopy (FTIR) results indicated that the grafting reaction took place, and HDDA has been grafted on PP skeleton. In comparison with initial PP, some modified samples showed lower melt flow index because of a large number of LCB in their skeleton. Several rheology plots were used to investigate the rheological properties of the initial PP and modified PPs, and the rheological characteristics confirmed the LCB in modified PPs skeleton. DSC results showed that the crystallization temperatures of modified PPs were higher than those of initial PP and degraded PP, suggesting that the modified PPs had long‐chain branched structure. The contrastive investigation in the rheology of modified PPs suggested that proper concentrations of HDDA and DCP were more beneficial to producing LCB during reactive extrusion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Toughened composites prepared from castor oil based polyurethane and soy dreg by a one‐step reactive extrusion process

A series of water‐resistant composites were successfully prepared from a mixture of soy dreg (SD), castor oil, and 2,4‐toluene diisocyanate (TDI) by a one‐step reactive extrusion (REX) process. The structure and properties of the composites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, dynamic mechanical analysis, tensile testing, and swelling experiments. The results indicated that the toughness of the composites prepared from castor oil based polyurethane and SD was significantly improved. In this case, TDI played an in situ compatibilization role through the crosslinking reaction of ? NCO groups with ? NH₂, ? NH? , and ? OH groups in SD and castor oil. With an increase in the molar ratio of ? NCO groups of TDI and ? OH groups of castor oil, the degree of crosslinking, tensile strength, glass‐transition temperature, water resistivity, and solvent resistivity of the composites increased. With an increase in the SD content of the composites, the tensile strength and solvent resistivity of the composites increased because of the reinforcement of the cellulose component in SD. This work provided a simple and effective way of preparing SD‐based composites by a REX process. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 953–960, 2006     

反应挤出马来酸酐接枝聚丙烯的结构与性能

选择最佳的配方和工艺条件,制备了每100g试样总酐基含量为8．1mmol的马来酸酐接枝聚丙烯(PP-g-MAH)产品、通过化学分离和红外光谱分析,发现PP-g-MAH产品的纯度很高,几乎没有游离态的MAH。广角X射线衍射实验发现,PP经过接枝处理后,晶型没有改变,但040晶面明显增大;晶胞在a和c轴上变化不大．在b轴上减小;结品度略有上升：通过分析接枝物的流变性能,发现接枝物与PP一样．仍属于非牛顿型假塑性流体。实验证明,PP-g-MAH产品具有良好的可注塑性。     

原位增容对反应挤出制备HDPE/PA6合金的影响

高密度聚乙烯(HDPE)/聚酰胺6(PA 6)合金挤出过程中的原位增容是通过马来酸酐(MAH)接枝HDPE(HDPE-g-MAH)引发己内酰胺(CL)聚合生成PA 6接枝HDPE(HDPE-g-PA 6)来实现的。通过改变HDPE-g-MAH含量,研究HDPE/PA 6合金反应挤出制备过程中,原位增容对合金的单体转化率和性能的影响。通过对合金中接枝物的提取和表征,可以确定在反应挤出过程中原位生成了接枝物HDPE-g-PA 6。通过场发射扫描电子显微镜和流变性能分析可知,随着HDPE-g-MAH含量增加,HDPE/PA 6合金中PA 6的尺寸减小,尺寸分布变窄;增加HDPE-g-MAH含量,原位生成的增容剂HDPE-g-PA 6数量增多,从而增强了界面结合力,改善了合金的相容性。     

High molecular weight thermoplastic polyether ester elastomer by reactive extrusion

A reactive branched thermoplastic polyether‐ester elastomer (TPEE) precursor was synthesized by the esterification reaction of dimethyl terephthalate (DMT) with poly(tetramethylene etherglycol) (PTMEG), 1,4‐butadiene, and glycerol as a soft segment, hard segment, and a branching agent, respectively. The high molecular weight TPEE was further synthesized with the prepared branched TPEE precursor, poly(butylene terephthalate) (PBT) and modified methylene diisocyanate (m‐MDI, 0.5–2.0 wt%) by the reactive extrusion method. Their chemical structures were determined by Fourier Transform Infra Red (FTIR) and Proton‐Nuclear Magnetic Resonance (¹H NMR). Thermal characteristics and rheological properties of TPEE were measured by Differential Scanning Calorimetry (DSC) and rheometer as a function of m‐MDI content. The intrinsic viscosity (IV) and melt index ratio (MIR) of TPEE increased as the content of m‐MDI increased up to 1.5 wt% and remained constant thereafter. The variation of the MIR was consistent with that of the IV. The storage modulus and viscosity did not vary with the measurement time up to 1.0 wt% of m‐MDI at the first extrusion, which indicates that the m‐MDI reacted fully. However, the viscosity and storage modulus increased with increasing measurement time at m‐MDI contents over 1.5 wt%. POLYM. ENG. SCI., 2009. © 2009 Societyof Plastics Engineers     

纺丝级尼龙6的反应挤出研究

利用阴离子开环聚合反应在双螺杆上快速制得了相对分子质量适当 ,相对分子质量分布较低(小于 3) ,单体含量低 (质量分数为 2 .5%～ 2 .8% ) ,流变性能好 ,易于纺丝的纺丝级尼龙 6。介绍了双螺杆反应挤出机的设计原理 ,讨论了催化剂、活化剂、助剂和挤出条件等因素对纺丝级尼龙 6的相对分子质量及其分布、残留单体量等的影响。实验发现 ,催化剂主要起引发反应的作用 ,活化剂则可大大加快反应速度 ,而助剂的加入可有效地提高聚合物的可纺性。     

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。     

Shape memory properties of polycaprolactone‐based polyurethanes prepared by reactive extrusion

The shape memory properties of polycaprolactone‐based polyurethanes (PCLUs) synthesized via a novel route of reactive extrusion were investigated in terms of the deformation amplitude, temperature, and rate by differential scanning calorimetry (DSC), dynamic mechanical analyzer, and polarized optical microscopy (POM). DSC analysis shows that the crystalline melting temperature and crystallinity of PCLU increased monotonically with increasing the average polymerization degree $ ( \overline {DPn}) $ of poly(ε‐caprolactone) (PCL) block. The retract force increased with increasing the temperature and reached the maximum (6–7 MPa) within 45–55°C. Furthermore, a modified model with two recovery stages was postulated to elucidate the shape memory process, which is visually presented by POM analysis. The two stages of tensile and compressive recovery are distinguished by the inflexion temperature, within 43–48°C and 64–66°C, respectively. The shape fixity is about 60–70% and can be improved to 100% by choosing proper deformation temperature. The tensile deformation recovery ratio was 80–98% due to the water absorption, whereas the compressive deformation recovery ratio was almost 100%. Besides, recovery tests show that the lowest recovery temperature ranged from 24 to 47°C was influenced by the deformation temperature, rate and the PCL block $ ( \overline {DPn}) $ . Thus, the shape memory properties can be adjusted according to different purposes. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Influence of in situ compatibilization on in situ formation of low‐density polyethylene/polyamide 6 blends by reactive extrusion

Low‐density polyethylene/polyamide 6 (LDPE/PA6) blends were in situ formed by reactive extrusion, in which in situ polymerization of ε‐caprolactam (CL) and in situ copolymerization of maleic anhydride grafted low‐density polyethylene (LDPE‐MA) and CL took place simultaneously. The latter reaction could be considered as in situ compatibilization, and the influence of in situ compatibilization on the morphologies, thermal properties, and rheological behaviors of the blends was investigated in this work. Scanning electron microscopy showed that the in situ compatibilization could dramatically reduce the dispersed phase sizes and narrow the size distribution. The thermal properties indicated that in differential scanning calorimetry (DSC) cooling scans, fractionated crystallization of the PA6 component was observed in all cases and was promoted with increasing the amount of LDPE‐MA. The DSC second heating scans showed the in situ compatibilization could stimulate the formation of the less stable γ‐crystalline form of PA6 in the blends. Dynamic rheological experiments revealed the in situ compatibilization had enhanced the viscosity, storage modulus, and loss modulus of the blend and reduce the corresponding slope values of the storage modulus and loss modulus. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study on composition and characteristics of maleated ethylene‐octene copolymer prepared by reactive extrusion on the morphology and properties of polyamide 6/ethylene‐octene copolymer blends

Blends of polyamide 6 (PA6) and elastomeric ethylene‐octene copolymer (EOR), with and without maleated EOR (EOR‐MA) were studied. EOR‐MA with various amounts of grafted MA and gel content were prepared by reactive extrusion. The effects of EOR‐MA characteristics and composition on the morphology, thermal and mechanical properties of the blends were investigated. EOR‐MA was found to promote the toughness efficiency of PA6 remarkably. High impact resistance was achieved by the use of EOR‐MA containing less than 2% gel. The content of MA grafted on EOR‐MA in the range of 0.5%–1.0% gave a similar effect on the blend properties. The blend containing 20% of EOR grafted with 1% MA exhibited twenty times higher impact strength (1000 J/m) than pure PA6 (55 J/m). The presence of EOR‐MA in the blends led not only to a drastic reduction in the dispersed particle size, but also to some changes in fracture mechanisms, thus enhancing the impact resistance of the blends.     

Mechanical properties of polyamide 6 reinforced microfibrilar composites

The mechanical behavior of microfibrilar composites (MFC), consisting of a matrix of high‐density polyethylene (HDPE) and reinforcement of polyamide 6 (PA6) fibrils, with and without compatibilization, was studied. The composites were produced by conventional processing techniques with various shape and arrangement of the PA6 reinforcing entities: long, unidirectional, or crossed bundles of fibrils (UDP and CPC, respectively), middle‐length, randomly oriented bristles (MRB), or non‐oriented micrometric PA6 spheres (NOM). The tensile, flexural, and impact properties of the MFC materials (UDP, CPC, and MRB) were determined as a function of the PA6 reinforcement shape, alignment and content, and compared with those of NOM, the non‐fibrous composite. It was concluded that the in‐situ MFC materials based on HDPE/PA6 blends display improvements in the mechanical behavior when compared with the neat HDPE matrix, e.g., up to 33% for the Young modulus, up to 119% for the ultimate tensile strength, and up to 80% for the flexural stiffness. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers