玻璃纤维毡增强聚丙烯材料（GMT）力学性能的研究

本文对影响玻纤毡增强聚丙的力学性能的各种因素进行了研究，探讨了炭黑种类及含量、改性ＰＰ的含量及对玻璃纤维毡结构等因素对ＧＭＴ材料的各项力学性能的影响，并得到炭黑的最佳种类、用量、改性ＰＰ的最和量及对玻璃纤维毡结构进行优化的途径。     

玻纤毡增强聚丙烯复合材料的增容及力学性能

通过玻璃纤维(GF)毡与双螺杆挤出相容剂改性聚丙烯(PP)膜的多层叠合,以熔融浸渍法制得PP基GF毡增强热塑性塑料(GMT)复合材料,研究了相容剂PP接枝马来酸酐(PP-g-MAH)和PP接枝丙烯酸(PP-g-AA)的用量(为PP基体质量的百分数)及其复配改性,以及相容剂改性PP基体分布和毡体种类对GMT力学性能的影响。结果表明,PPg-MAH可明显提高GMT的拉伸与弯曲性能,但降低了冲击性能;PP-g-AA可明显提高GMT的冲击性能,但不利于拉伸与弯曲性能的提高,只有当PP-g-AA用量超过5%后,拉伸性能才有所提升。在PP-g-MAH用量为3%的条件下,将其与不同用量的PP-g-AA进行复配改性没有对GMT力学性能产生协同作用。在各相容剂用量相近(3%~3.5%)的情况下,与相容剂复配改性GMT相比,以两层PP-g-AA改性PP为芯层、PP-g-MAH改性PP为上下表面层作为改性基体分布时,GMT拉伸与弯曲强度分别提高17%和27%、缺口冲击强度提高48%;而以两层PP-g-MAH改性PP为芯层、PP-g-AA改性PP为上下表面层作为改性基体分布时,在不损失强度与刚性的同时,缺口冲击强度提高了88%。采用连续GF毡的GMT力学性能比采用短切GF毡的GMT高,尤其是缺口冲击强度提高了89.6%。     

Variable frequency microwave processing of thermoplastic composites

Abstract

The range of applications for variable frequency microwave (VFM) facilities (2–18 GHz) has been extended to thermoplastic composites. Five thermoplastic polymer matrix composites are processed and discussed, including 33 wt-% random carbon fibre reinforced polystyrene [PS–CF (33%)], and low density polyethylene [LDPE–CF (33%)]; 33 wt-% random glass fibre reinforced polystyrene [PS–GF (33%)], low density polyethylene [LDPE–GF (33%)]and Nylon 66 [Nylon 66–GF (33%)]. Bond strengths of lap joints were tested in shear and results were compared with those obtained using fixed frequency (2·45 GHz) microwave processing. The primer or coupling agent used was a 5 min, two part adhesive containing 100%liquid epoxy and 8% amine, which was more readily microwave reactive than the composites themselves. The VFM was operated under software control, which provided automatic data logging facilities. Results indicate that VFM can produce strong bonds for PS and LDPE.     

Swirl mat– and long discontinuous fiber mat–reinforced polypropylene composites—status and future trends

Polypropylene (PP) composites with glass and natural fiber mat reinforcement (GMT‐PP and NMT‐PP, respectively) are widely used in different applications, competing with metallic sheets and thermoset polymer composites. Their production occurs via melt impregnation, slurry deposition and various textile architecturing processes that lead to either consolidated or non‐consolidated preforms. These preforms are then converted into final parts by hot pressing. The “traditional” GMT‐PP composites are nowadays faced with a great challenge because of the introduction of long fiber reinforced thermoplastic (LFT) composites produced on‐ or off‐line. This paper gives a brief survey on the manufacturing, processing, properties and application of GMT and GMT‐like systems and it concludes by describing some of the future trends, especially in the fields of material and process developments.     

Flax fibre physical structure and its effect on composite properties: Impact strength and thermo-mechanical properties

Earlier investigations by the authors showed that the tensile modulus of flax fibre mat polypropylene composites (NMT) could surpass the values of glass mat reinforced thermoplastic (GMT) on fibre weight basis. The tensile and flexural strength could reach values of up to 65% of the GMT strength values, however, very much dependent on the fibre physical structure. This study deals with the Charpy impact and the thermo-mechanical properties of flax NMT materials. The trend is that the Charpy impact strength decreases with increasing fibre internal bonding and enhanced fibre-matrix adhesion, which is opposite to the trend for the tensile and flexural properties. The impact strength of the NMT materials is lower than generally reported for GMT materials. Dynamic mechanical thermal analysis reveals that with increasing temperature the storage modulus of the NMT materials reduces more slowly when the fibre internal bonding and the fibre-matrix adhesion are improved. In order to approach the tensile, flexural and impact strength of GMT materials, composites should be based on the strong elementary flax fibres. The axial tensile strength of elementary fibres approaches the strength of glass fibres and the lateral strength of the elementary fibres is higher than the technical flax fibres lateral strength. The thermo-mechanical properties can probably be improved when non-cellulosic material can be removed from the flax fibre surface without damaging the fibre.     

Graded glass mat–reinforced polypropylene

In the impregnation process, when pressure is applied, the dry fiber preform is first compressed and then unloads as the matrix flows within the pores. It has been shown earlier that for glass mat–reinforced thermoplastic (GMT) materials, the time to provide complete infiltration of the matrix is significantly shorter than the unloading time of the reinforcement. This effect is exploited here to control the processing time in order to provide full infiltration but limited relaxation of the fiber bed, thereby producing a graded fiber content structure. Symmetric glass fiber/polypropylene (PP) composites were impregnated for different processing times to produce parts with a higher fiber content on the surface, decreasing towards the center. The elastic modulus in bending of the GMT parts was measured by a three‐point flexure test while the distribution of fibers in the matrix was quantified using optical microscopy combined with image analysis. The flexural modulus of GMT was found to decrease with the impregnation time, in good agreement with the prediction from infiltration and mechanics theory. Controlled processing could therefore be used to maximize the bending stiffness of GMT. POLYM. COMPOS., 26:361–369, 2005. © 2005 Society of Plastics Engineers.     

Processing and applications of new class of glass fibrerecyclate

Abstract

Novel recycling technology has resulted in a new type of E-glass fibre product, Fiberlets, recovered from fibre manufacturers' in house waste. An interesting characteristic is its low aspect ratio, which gives it the ability to pack efficiently, enabling high glass content products to be achieved without an unduly large increase in viscosity that could affect processability. This paper reports an initial study, which shows that the material can be used in both thermosetting and thermoplastic moulding materials. Synergistic effects have been found with combinations of Fiberlets and conventional short fibre reinforcement in bulk moulding compounds. In thermoplastic moulding materials, benefits include improvements in modulus and creep, with the possibility of making readily processable compounds with high inorganic content. Applications therefore include cost effective bulk moulding compounds and high glass content thermoplastic moulding materials with improved creep behaviour. Several other uses are envisaged, in applications for which milled glass, glass beads, and mineral fillers are currently used.     

PP-g-MAH预浸渍玻璃纤维毡对GMT界面改性的作用

采用含有马来酸酐接枝聚丙烯(PP–g–MAH,简称MPP)的聚丙烯(PP)树脂对玻璃纤维(GF)毡预浸渍,进行增强体改性,通过直接浸渍工艺、增强体预浸渍工艺、累加浸渍工艺等不同工艺制备GF毡增强PP热塑性复合材料(GMT)。对不同工艺制备的GMT界面形态进行了扫描电子显微镜分析,并测定了预浸渍处理后GF的疏水性,研究了预浸渍工艺中MPP的用量对GMT拉伸、弯曲、冲击等力学性能的影响。结果表明:采用含MPP的PP树脂进行增强体预浸渍改性的方法,改性树脂对GF的包覆效果良好,经预浸渍改性法处理的GF,其疏水性增强;并可以获得与PP/MPP改性树脂直接浸渍GF毡时相似的界面改性效果和相近的GMT力学性能;样品界面改性效果相近的情况下,增强体预浸渍改性方法所需的MPP用量明显少于改性树脂直接浸渍时的用量。     

Development of glass fibre reinforced polyethylene pipes for pressure applications

Abstract

Thermoplastic filament winding with in line melt impregnation has been investigated for the manufacture of continuous glass fibre reinforced thermoplastic pipes. With polyethylene matrixes it was found that the high melt viscosity hindered full melt impregnation and resulted in high pull forces in the case of pipe grade polyethylene. Using a lower viscosity polyethylene it was possible to operate the melt impregnation process, but the product obtained exhibited a high void content. Surprisingly, it was found that filament winding resulted in a considerable decrease in void content, to an acceptable level. It was found possible to wind good quality pipes and achieve high failure pressures that fully reflected the strength of the reinforcement.

The non-linear strain response of glass–polyethylene pipes can be modelled using laminate theory modified to take account of the non-linearity of the matrix and the change in fibre angle that occurs as the pipe deforms.     

树脂基复合材料在汽车上的应用分析

轻量化、绿色环保和舒适安全性将成为我国汽车用材料未来发展方向,树脂基复合材料将是实现汽车轻量化、塑料化的材料之一.介绍了玻璃纤维毡增强热塑性复合材料(GMT)、长纤维增强热塑性复合材料(LET)、天然纤维增强热塑性复合材料(NMT)和碳纤维增强复合材料(CFRP)等的特点和应用实例分析.树脂基复合材料的应用是汽车轻量化设计和选材的发展趋势.     

Tensile and Impact Properties of Thermoplastic Natural Rubber Reinforced Short Glass Fiber and Empty Fruit Bunch Hybrid Composites

Thermoplastic natural rubber (TPNR) hybrid composite with short glass fiber (GF) and empty fruit bunch (EFB) fiber were prepared via the melt blending method using an internal mixer type Thermo Haake 600p. The TPNR were prepared from natural rubber (NR), liquid natural rubber (LNR) and polypropylene (PP) thermoplastic, with a ratio of 20:10:70. The hybrid composites were prepared at various ratios of GF/EFB with 20% volume fraction. Premixture was performed before the material was discharged into the machine. The study also focused on the effect of fiber (glass and EFB) treatment using silane and maleic anhydride grafted polypropylene (MAgPP) as a coupling agent. In general, composite that contains 10% EFB/10% glass fiber gave an optimum tensile and impact strength for treated and untreated hybrid composites. Tensile properties increase with addition of a coupling agent because of the existence of adherence as shown in the scanning electron microscopy (SEM) micrograph. Further addition of EFB exceeding 10% reduced the Young's modulus and impact strength. However, the hardness increases with the addition of EFB fiber for the untreated composite and decreases for the treated composite.     

Structure and properties of PP/SBS/glass fiber hybrid composites. Past II: Property measurement

The mechanical properties viz. impact and tensile modulus of hybrid composites of PP/SBS/glass in the composition range 0‐40 wt% of glass fibers (GF) were studied. Both impact and tensile modulus increased with respect to glass content at a certain composition of the blend. Synergistic effects were seen in the value of elongation and toughness at a certain composition of the glass content. The above findings could be associated with the high aspect ratio and nucleation ability of GF together with good interfacial adhesion between the GF and SBS, rather than the PP matrix. These have been supported by the investigations on structures and morphologies of the hybrid composites.     

Welding of thermoplastics reinforced with random glass mat

Thermoplastics reinforced with random glass mat have high strength and stiffness; the fibers dominate the mechanical behavior of these composites. The results of this investigation have shown that fibers are ineffective for reinforcing hot-tool and vibration welded butt welds. The maximum weld strengths attained with GMT are comparable to the strengths of good welds of the unfilled material. The optimum hot-tool welding parameters for the reinforced materials are different from those for the unfilled material. Unfilled polypropylene is easier to weld than unfilled polyamide. This characteristic is also true of the reinforced materials. In vibration welding, high welding pressures and high amplitudes result in lower mechanical properties. The optimum penetration depends on the fiber content of the bulk material. This penetration dependence is different from that for unfilled thermoplastic, for which the mechanical properties are independent of the penetration once a steady state has been attained.     

玻纤增强基材的创新与发展

分析了当今下游复合材料工业的发展对玻纤增强基材发展的需要。重点介绍了风电叶片用玻纤纱、技术织物、复合织物、预浸渍制品、预成型增强体等各类玻纤增强基材以及增强热塑性塑料用的短切纤维、混合纱、LFT、GMT、GMT-D、LFT—D、增强热塑性片材等各类玻纤增强基材。并为玻纤增强基材如何促进这两类复合材料产品的发展提出建议。     

Mechanical properties of polypropylene composites reinforced with long glass fibres and mineral fillers

Abstract

The mechanical behaviour of long discontinuous glass fibre (LGF) reinforced polypropylene (PP) composites filled with talc or calcium carbonate fillers was studied. Sample specimens were processed by injection moulding, after which tensile and impact properties were analysed. In addition, scanning electron microscopy was used to analyse the morphology of the fracture surfaces. The results showed that the use of talc as a hybrid filler in LGF reinforced PP leads to a better tensile strength and toughness than in a corresponding hybrid composite based on calcium carbonate. Furthermore, it was observed that the matrix had a dominant role at low fibre content, whereas at high fibre loading, the effect of fibres was more evident.     

注塑工艺制备玻璃纤维增强聚合物研究

采用碱性短玻璃纤维增强PP,通过混合-注塑工艺制备玻璃纤维/PP复合材料,并较全面的研究了玻纤含量、长度、偶联剂类型与加入量对复合材料力学性能的影响。结果表明:随着玻纤含量的增加,复合材料的力学性能有明显的提高,增加到35%时性能最佳;并且发现纤维长度越长,增强的幅度越大;随着注塑次数的增多,聚合物的拉伸强度先大后小,证实3次较好;说明用注塑法来制备短纤维增强PP复合材料是完全可行的。     

MAH—g—PP孚L液对PP／GF复合材料界面的影响

利用自制的MAH—g—PP乳液和KH-550溶液组合进行玻纤的表面处理。考察了MAH—g—PP乳液和KH-550溶液处理对PP／GF界面粘结的影响,研究了MAH—g—PP乳液处理玻纤表面的适宜温度和时间,探讨了MAH—g—PP乳液对PP／GF的偶联机理。结果表面：玻纤表面经MAH—g—PP乳液和KH-550溶液处理后,在PP／GF界面上形成了牢固的化学键连接,出现了明显的横晶层;MAH—g—PP乳液处理玻纤表面的适宜温度和时间为105℃、1h;MAH—g—PP乳液对PP／GF的偶联机理为乳液中的羧基与玻纤表面KH-550的氨基发生化学键合。     

加压方式对PP／GMT片材孔隙含量和弯曲性能的影响

针对ＰＰ／ＧＭＴ体系,研究了以加压和辊筒加压两种方式下温度和压力对片材孔隙含量和弯曲强度的影响,得了了两种加压方式下的最佳浸渍温度和压力。实验中的各种条件下,辊筒加压所得片材的孔隙含量均低于平板加压所得片材的孔隙含量,而弯曲强度均较高,因而。中压方式明显优于平板加压方式。     

热塑性GMT片材预热技术研究

较为系统地研究了热塑性复合材料GMT片材的预热过程 ,对热板接触、热空气对流及远红外预热过程进行了对比实验研究。热板接触式预热能够使片材快速均匀升温 ,但预热后的片材与热板发生粘附 ;远红外预热虽然升温速率很快 ,但是在片材内部形成较大的温度梯度 ;热空气对流预热的升温速率较慢 ,但片材内部温度梯度很小 ,且可加工区间较宽 ,便于控制     

Structure and properties of PP/SBS/glass fiber hybrid composites. Part I: Crystallization behavior and morphology

The structure development, crystallization behavior and morphology were studied in hybrid composites made with polypropylene/styrene‐butadiene‐styrene (PP/SBS) containing glass fibers (GF). The techniques applied include optical polarizing microscopy, X‐ray diffraction and scanning electron microscopy (SEM). The isothermal crystallization studies of PP/SBS/GF revealed that SBS as well as GF could act as good nucleating agents for PP. However, the nucleation efficiency of GF is much higher than that of the SBS. At high concentrations of SBS (> 30%), the crystallization rate decreases even in the presence of GF. This was attributed to the strong bonding between SBS and glass, giving rise to an intermediate layer of SBS between PP and GF, which was confirmed from the SEM of the fractured morphology of the injection molded hybrid composite. The orientation of GF was observer in the injection molded samples for certain compositions, and this was accompanied by an increase of intensities of particular diffraction peaks in the XRD.