汽车水室用增强PA66复合材料的研制

通过特殊的螺杆组合工艺,制备了汽车水室用增强尼龙( PA) 66复合材料,分别考察了螺杆组合、耐水解玻纤和耐水解剂对材料性能和表面质量的影响.结果表明,螺杆组合对玻纤的保留长度和分布影响显著.耐水解玻纤的加入大大提高了材料的耐水解性能,自制耐水解剂能有效地防止材料表面出现裂纹.所研制的增强PA66复合材料目前已成功用于...     

Influence of screw configuration and processing temperature on the properties of short glass fiber reinforced polypropylene composites

Short glass fiber reinforced polymers are used in many different applications due to their good property profiles. These properties are directly correlated with the fiber length present in the final composite, which can be influenced through the process. Therefore, the aim of this work was to investigate the influence of processing temperature and screw configuration in compounding on the properties of glass fiber reinforced polypropylene. On the one hand, the barrel temperature was varied between 180°C and 260°C and, on the other hand, four different screw configurations were applied using a standard temperature profile. Specimens were produced by injection molding, which were tested via mechanical characterization, density, and fiber length measurements as well as morphology through microscopical analysis. We found, that with higher barrel temperatures and screw configurations bringing lower shear into the melt the glass fiber length is preserved better, thus resulting in improved composite properties. Also the interfacial interaction is not influenced within the investigated parameters, as was checked via the application of a micromechanical model in composite strength. POLYM. ENG. SCI., 59:1552–1559 2019. © 2019 Society of Plastics Engineers     

The processing of fiber reinforced thermoplastics using co-rotating twin screw extruders

For short fiber reinforced thermoplastics the effect of fiber length and the fiber/matrix bond on the ultimate properties of the material are well understood. But, how the process conditions under which the composite is made affect the fiber length and the fiber matrix bond has not been so thoroughly reported in the literature. A study of this relationship has been made on a co-rotating twin screw extruder incorporating 30 percent by weight of glass fiber into nylon 66 to make the composite. Experimental results are presented to show how machine variables such as mixing configuration and screw speed affect the material properties and process efficiency. The properties of the composite were assessed by measurement of the fiber length distribution and tensile strength. From the results in the text it is possible to select machine variables to give desired production conditions. Although most of the work concerns the twin screw extruder, some of the consequences of subsequent injection molding are also shown.     

Correlation between processing conditions and fiber breakage during compounding of glass fiber‐reinforced polyamide

The inter‐relationship between processing conditions and fiber breakage has been studied for glass fiber‐reinforcedpolyamide 12, prepared using (i) an internal batch mixer, (ii) a laboratory scale corotating twin screw extruder, and (iii) an industrial scale twin screw extruder. The average fiber lengths and fiber length distributions were measured for various compounding conditions (screw or rotor speed, mixing time, feed rate). Experimental results have shown that fiber breakage depends on both screw speed and mixing time, the later being controlled, in an extruder, by the feed rate. For a given compounding system (batch mixer or twin screw extruder), the energy input (specific mechanical energy, SME) during the compounding process is found to be a reliable parameter, which governs fiber length (average, minimal, and maximal) evolution. Experimental data are correctly described with a model defining change in fiber length as a function of SME. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Glass fiber breakup in corotating twin screw extruder: Simulation and experiment

The damage of glass fibers at various conditions was investigated in a corotating twin screw extruder by varying viscosity, screw speed, and screw configuration. Increasing the screw speed and melt matrix viscosity were found to increase the extent of fiber breakage. Based on the experimental data and Euler buckling theory, a composite modular kinetic model to describe glass fiber breakage was developed. Regions of the major and minor fiber breakage in a corotating twin screw extruder were found. The simulation program based on the experimental data and kinetic constants was developed for fiber breakage along the screw length. Comparisons were made between simulated results and experimental data indicating a reasonable quantitative agreement between them. Predictions of the model are also in general qualitative agreement with many published data on fiber breakage in twin screw extruders. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

玻璃微珠改性PP和LLDPE力学性能的比较研究

采用玻璃微珠(GB)改性聚丙烯(PP)和线性低密度聚乙烯(LLDPE)，对玻璃微珠的用量、粒径和复合材料加工方法对材料的力学性能的影响进行了比较研究。结果表明：随着GB用量的增加，单、双螺杆挤出GB／PP复合材料的拉伸模量、弯曲强度和弯曲模量均呈线性增长的趋势，而屈服强度则有小幅下降；断裂应变在低含量时有所提高，然后迅速下降；单双螺杆挤出材料的冲击强度均有所提高，并在一定范围内随GB用量的提高而增大，且单螺杆挤出材料的冲击强度略高于双螺杆挤出材料。而GB／LLDPE中，随着GB用量的增加，单螺杆挤出复合材料的拉伸模量、弯曲模量均呈线性增长趋势，而屈服强度和弯曲强度在含量较高时略有上升；双螺杆挤出复合材料的拉伸模量、屈服应力、弯曲强度和弯曲模量均呈线性增长的趋势，两者的断裂应变都有所降低，但没有严重劣化LLDPE复合材料的冲击特性。GB的粒径对两种复合材料的力学性能影响不大，但对GB／PP复合材料的韧性有较大影响。单、双螺杆挤出GB／PP复合材料的冲击强度在一定范围内较纯料有一定提高；同样的，双螺杆挤出复合材料的冲击强度低于单螺杆挤出材料。     

增强增韧尼龙6挤出工艺及纤维分散研究

使用双螺杆挤出机制备了增强增韧尼龙6,研究了不同挤出温度、螺杆转速对连续玻纤和短切玻纤增强材料力学性能的影响,使用统计法分析了材料中玻纤分散情况。结果表明,短切玻纤增强的力学材料性能高于连续玻纤增强材料。当螺杆转速为350 r/min,挤出温度为240~260℃时材料的性能较佳。     

玻纤增强尼龙6的挤出工艺及力学性能

采用长玻纤连续添加和短切玻纤制备了玻纤增强尼龙6(PA6)复合材料。主要考察了玻纤含量、玻纤种类以及挤出工艺条件对复合材料力学性能的影响,并利用扫描电子显微镜对复合材料的冲击断面和拉伸断面及玻纤形态进行了观察。结果表明,采用短切玻纤加入时,玻纤含量对GF/PA6复合材料的力学性能影响很大。随玻纤含量的增加,复合材料的力学性能越来越高,断裂伸长率变低。加工工艺参数对复合材料的力学性能有影响。采用长玻纤连续添加时,玻纤的添加位置对复合材料的性能影响不大。在玻纤含量相同时,采用长玻纤连续添加得到的材料力学性能明显优于采用短切玻纤时的性能。玻纤能均匀地分散在PA6基体中,玻纤的保留长度和长度分布对复合材料的性能有直接影响。     

混合元件对玻璃纤维增强聚丙烯中玻璃纤维长度的影响

对啮合同向双螺杆挤出机90 °捏合块、六棱柱、变间隙转子3种混合元件流道流场进行了数值模拟,分析3种元件的混合性能。实验研究了使用3种不同元件的螺杆组合对玻璃纤维增强聚丙烯（GFRPP）复合材料中玻璃纤维长度的影响。结果表明,啮合同向双螺杆挤出机中聚合物熔体产生的剪切对玻璃纤维长度影响明显,混合元件的剪切越强,制品中玻璃纤维的平均长度就越短,制品的拉伸强度和冲击强度越低。     

螺杆组合对玻纤增强聚酰胺66纤维长度及力学性能的影响

研究了在同向双螺杆挤出机不同混合段螺杆组合下制备玻璃纤维(GF)增强聚酰胺66(PA66)复合材料时的纤维破坏情况,并通过沿螺杆轴向取样分析纤维长度沿挤出方向的变化规律,研究了不同螺杆组合对制品力学性能的影响,设计出适合于PA66/马来酸酐接枝乙烯辛烯共聚物(POE-g-MAH)/GF体系的螺杆组合。结果表明,合理设计纤维加入后的螺杆组合可以有效提高剩余纤维长度及制品的力学性能,同捏合块相比,使用反向齿形盘能够在提供较强混合能力的同时保证较低的剪切强度,从而有利于保持纤维长度,并有助于纤维的分散及物料的混合;将混合元件分开布置,并用输送元件将其分隔开,有助于提高输送能力,保持纤维长度。     

Relationship between processing method and microstructural and mechanical properties of poly(ethylene terephthalate)/short glass fiber composites

Composites of recycled poly(ethylene terephthalate) (PET) reinforced with short glass fiber (GF) (0, 20, 30, and 40 wt %) were compounded in a single‐screw extruder (SSE) and in a intermeshing corotating twin‐screw extruder (TSE). An SSE fitted with a barrier double‐flight screw melting section in between two single‐flight sections and a TSE with a typical screw configuration for this purpose were used. The composites were subsequently injection molded at two different mold temperatures (10 and 120°C), with all other operative molding parameters kept constant. The effects of processing conditions on composite microstructure, PET degree of crystallinity, and composite mechanical properties were evaluated. Appropriate dispersive and distributive mixing of the glass fiber throughout the PET matrix as well as fine composite mechanical and thermal‐mechanical properties were achieved regardless of whether the composites were prepared in the SSE or TSE. The performance of the SSE was attributed to the efficiency of the barrier screw melting section in composite mixing. The mold temperature influenced the mechanical properties of the composites, by controlling of the degree of crystallinity of the PET in the composites. For a good balance of mechanical and thermal‐mechanical properties, high mold temperatures are desirable, typically, 120°C for a mold cooling time of 45 s. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Effects of processing conditions on the fiber length distribution and mechanical properties of glass fiber reinforced nylon‐6

The effects of processing conditions on fiber length degradation were investigated in order to produce composites with higher performance. Nylon‐6 was compounded with glass fibers in a twin‐screw extruder for various combinations of screw speed and feed rate. Collected samples were injection molded and Izod impact and tensile tests were performed in order to observe the effect of fiber length on the mechanical properties. Also, by using the extruded and injection molded smaples, fiber length distribution curves were obtained for all the experimental runs. Results show that when the shear rate is increased through the alteration of the screw speed and/or the feed rate, the average fiber length decreases. Impact strength, tensile modulus and tensile strength increase, whereas elongation at break decreases with the average fiber length.     

Polypropylene/low density polyethylene blend matrices and short glass fibers based composites. I. Mechanical degradation of fibers as a function of processing method

The fiber length degradation during compounding (two-roll milling and twin-screw extrusion) of glass fiber and polypropylene (PP)/low density polyethylene (LDPE) blend matrices based composites was investigated. The effect of LDPE percentage and fiber content on fiber length were studied using a semiautomatic image analysis system. Two-roll milling causes a more severe attrition of the fibers than twin-screw extrusion. In the first case, the higher the LDPE percentage in the polymer matrix, the larger the final fiber length. Both methods lead to a broader fiber length distribution as LDPE percentage increases. The effect of fiber content is opposite to that of the LDPE percentage, but in the case of twin-screw extrusion it is less noticeable, During the injection molding of the composites a slight decrease of the final fiber length takes place. This decrease depends on the initial fiber length, the effect being more pronounced for longer fibers.     

废弃木粉与短切玻璃纤维组合增强聚丙烯的力学性能

用废弃木粉与短切玻璃纤维作为增强材料，制得了组合增强的聚丙烯复合材料，研究了制备工艺及设备、材料配方及界面改性方法等对材料力学性能的影响。结果表明，用单螺杆挤出机制备组合增强材料，可减少对玻璃纤维的损伤，保持较长的玻璃纤维，有利于其增强作用的发挥；随着玻璃纤维含量的增加，体系的力学性能提高，而木粉含量对材料力学性能的影响与玻璃纤维的含量相关；采用硅烷偶联剂对木粉进行表面处理，在基体中添加接枝极性基团的改性聚丙烯，可改善体系的界面结合，提高力学性能。     

Effects of processing conditions on the mechanical performance of maleic anhydride compatibilized in-situ composites of polypropylene with liquid crystalline polymer

Maleic anhydride compatibilized blends of isotactic polypropylene (PP) and thermotropic liquid crystaline polymer (LCP) were prepared either by the direct injection molding (one-step process), or by twin-screw extrusion blending, after which specimens were injection molded (two-step process). The morphology and mechanical properties of these injection molded in situ LCP composites were studied by means of scanning electron microscopy (SEM), Izod impact testing, static tensile, and dynamic mechanical measurements. SEM observations showed that fine and elongated LCP fibrils are formed in the maleic anhydride compatibilized in situ composites fabricated by means of the one-step process. The tensile strength and modulus of these composites were considerably close to those predicted from the rule of mixtures. Furthermore, the impact behavior of LCP fibril reinforced composites was similar to that of the glass fiber reinforced polymer composites. On the other hand, the maleic anhydride compatibilized blends prepared from the two-step process showed lower mechanical performance, which was attributed to the poorer processing behavior leading to the degradation of PP. The effects of the processing steps, temperatures, and compatibilizer addition on the mechanical properties of the PP/LCP blends are discussed.     

Melt Processing of Ethylene-Acrylic Acid Copolymer Composites Reinforced with Nanocellulose

To investigate the impact of process design factors such as number of passes, screw design and screw type, a poly(ethylene-co-acrylic acid) and a masterbatch containing 40 vol% nanocellulose were compounded using a twin-screw extruder with two different screw configurations. The 20 vol% composite pellets obtained, containing nanocellulose of different morphologies, cellulose nanofibrils and cellulose nanocrystals, were re-extruded several times to study the effect of re-extrusion. The compounded pellets were extruded into films using a single-screw extruder. These films contained aggregates of the nanocellulose material, which was reduced in size upon re-extrusion leading to an improvement in properties of the composites. With the best combination of process factors, the Young's modulus and stress at break of the composites increased by factors of 10 and 1.6, respectively. The presence of a strong network of the cellulosic entities was observed qualitatively using melt rheology upon re-extrusion. Re-extrusion had a negligible effect on the crystallinity of the composites. POLYM. ENG. SCI., 60:956–967, 2020. © 2020 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.     

Effects of thermal history on mechanical behavior of PEEK and its short-fiber composites

The effect of crystallinity differences induced by mold wall temperature and annealing on mechanical behavior is evaluated for poly(etheretherketone) (PEEK) resin and its composites. The systems investigated were neat PEEK, glass fiber (GF) reinforced PEEK, and carbon fiber (CF) reinforced PEEK. Both composite systems were reinforced with 10, 20, and 30 wt% fiber. The degree of crystallinity (X_c) of PEEK was found to increase by processing at higher mold temperatures, by annealing, and by fiber length reductions, which appears to indicate the ability of short fibers to nucleate the crystallization of PEEK under favorable thermal conditions. Improvements in Young's modulus and strength together with ductility reductions are generally obtained as crystallinity increases in both neat PEEK and its composites. The contribution of crystallinity to mechanical behavior is significant only for neat PEEK and PEEK reinforced by 10% fiber. SEM micrographs reveal that this is due to a change in failure mode. When PEEK is reinforced by carbon fibers or by 20–30% glass fibers, a macroscopic brittle mode of failure is observed irrespective of matrix crystallinity, and mechanical behavior is principally determined by the nature and content of the reinforcing fibers.     

Effect of screw design on fiber damage in extrusion compounding and composite properties

The mechanism of fiber length degradation during twin screw extrusion compounding and methods to reduce it through process and machine design are extremely important in discontinuous fiber reinforced composites. Fiber damage along the screw and the extruder die are determined for three screw designs with different mixing sections. The pellet quality, wet-out, and fiber dispersion in the extruded strands are compared. The fiber orientation distributions in the screw are determined to identify regions of higher fiber interaction. The fiber damage during subsequent injection molding has also been determined. The tensile, flexural, and impact properties of the tensile bars are compared. It is found that the residence time, fill-up, and the intesity of mixing during extrusion compounding have a predominant effect on fiber length degradation. The screw designs were seen to have a greater effect on the fiber damage in the 40 wt% glass-filled polymer than the 30 wt% glass-filled polymer. However, the mechanical properties of the 30 wt% glass-filled polymer showed an increasing trend compared to the 40 wt% glass filled polymer. A screw design that provides a balance of the fiber length, wet-out, and fiber dispersion was noted to give consistent mechanical properties.     

尼龙66高铁专用材料的研究

采用双螺杆挤出加工工艺,对尼龙66材料增强增韧进行了研究,深入探讨了玻璃纤维、增韧剂及助剂等材料对尼龙66的性能影响,确定了合金复合尼龙材料的最佳工艺参数和配方,所制备的尼龙复合材料可以达到高铁用尼龙材料的性能要求.