Effect of twisting on mechanical properties of GF/PP commingled hybrid yarns and UD‐composites

This study was conducted due to the necessity for improving the processability of commingled yarns during textile processing, in particular dense 3D preform weaving. Open structure of the commingled yarns caused higher production stops. As a possible solution, GF/PP commingled yarns with different twisting levels were produced. Effect of twisting on the mechanical properties of commingled yarns and on their compression molded UD composites are determined. Further tests were executed about yarn/yarn and yarn/metal friction of twisted commingled yarns, which are important properties during textile processing. Theoretical approaches such as a yarn model with linear bar elements and lamina equation with an equivalent angle distortion of over‐delivery proved useful to relate the structural parameters and mechanical properties. As a result, twisting did not significantly affect the modulus of elasticity of UD‐composites, however, the tensile strength of UD‐composites were reduced by further processing even without twisting. Therefore, small twisting levels can be applied on commingled yarns to improve processability of dense preforms without significantly affecting the mechanical performance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Processability and mechanical properties of ternary composites PP/EPDM/GF

The enhancement of the mechanical properties of neat PP is achieved by the addition of glass fibers and EPDM rubber. The Young's modulus and notched Charpy impact strength of the composites obtained are improved with respect to the original polymer, leading to a new composite material with a very good balance of toughness and rigidity properties. The tensile behavior of these multiphase systems is successfully compared with theoretical predictions using the Halpin‐Tsai/Nielsen theory for uniaxially short fiber composites, which considers the matrix as a blend with spherical particles and can predict the tensile modulus considering an average fiber orientation angle. An accurate morphological study performed by scanning electron microscopy (SEM) shows a very good dispersion of the rubbery phase into the neat matrix. No special affinity between the rubber and the fibers is reported. The good dispersion and the small particle diameter indicate the good processability of the ternary systems studied.     

短切玻璃纤维(GF)增强PET复合材料的研究

通过溶液法制备了短切玻璃纤维增强PET复合材料;研究了短切玻璃纤维含量和长度对PET／GF复合材料强度的影响;并对试样冲击断口的显微结构和断裂形态进行了分析。结果表明,复合材料的强度随玻璃纤维含量的增加先提高后降低,即出现极值,随玻璃纤维长度的增加其强度略有提高;且要制得玻璃纤维分布均匀的PET／GF复合材料;KH550是PET／GF复合体系的良好偶联剂。     

Dynamic mechanical analysis of novel composites from commingled polypropylene fiber and banana fiber

Polypropylene (PP)/banana fiber (BF) composites were fabricated from PP fiber and short BF by novel commingling method. The dynamic mechanical analysis (DMA) of the composites was performed with reference to BF loading and fiber surface treatments. By the incorporation of BF into the PP matrix, the storage modulus and loss modulus have been found to increase, whereas damping factor has been found to decrease. Glass transition temperature was found to increase with increase in BF loading. The viscoelastic properties of the composites were also found to depend on fiber surface treatments. The activation energy of the composites for the glass transition has been found to be increased by the increase in BF loading. Surface treatment of the BF further increased the activation energy of the composites, indicating a stronger interface for treated fiber composites. Scanning electron microscopy (SEM) photographs of the BF showed the physical changes induced by the surface treatments. Fourier transform infrared spectroscopy (FTIR) was used to ascertain the existence of the type of interfacial bonds. The use of theoretical equations to predict the storage modulus has also been discussed. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Influence of the impregnating property on mechanical properties of commingled yarn composites

Three types of glass/nylon 6 intermediate material forms-film stacking, uncommingled yarn, and commingled yarm-were selected study the correlations between the impregnating property and mechanical properties. The size of the glass fiber block to be filled with matrix and the porosity in glass fiber bundles by spearing out the fiber bundle was different in these materials. Unidirectional glass fiber reinforced thermoplastic composites were fabricated by compression molding. The being test was performed by using the three-point loading system, and the fracture behavior and the degree of impregnation were observed to examine the influence of processing conditions on the bending properties, relative to the form of the intermediate material. Bending strength increased, in accordance with the impregnating property, least in the film stacking form, second most in uncommingled yarn, and most in commingled yarn. The impregnating property was affected by the size of fiber blocks and the porosity in fiber bundles, because bending strength was improved by spreading out the fiber bundles. Commingled yarn is an excellent intermediate materials, which has both the fineness of matrix/fiber mixing and large porosity in fiber bundles.     

热塑性复合材料用玻纤／涤纶摩擦纺包芯纱的性能分析

摩擦纺包芯纱是加工热塑性树脂基复合材料的一种好方法,但以玻璃纤维长丝为芯纱的包芯纱与普通服用包芯纱存在很大的差异。实验对不同参数玻璃纤维／涤纶包芯纱的性能进行了研究,结果表明：各存在一个临界摩擦比值,相对应摩擦纺包芯纱的捻度最大、断裂强度最大和抗剥离性最好;但当摩擦比提高到4以上时,条干均匀性变化趋缓。指出可通过后道工序对摩擦纺包芯纱的要求来选择不同工艺参数的摩擦纺包芯纱。这对后道纺织预型件加工和复合材料成型有重要意义。     

热塑性复合材料用玻纤/涤纶摩擦纺包芯纱的性能分析

摩擦纺包芯纱是加工热塑性树脂基复合材料的一种好方法,但以玻璃纤维长丝为芯纱的包芯纱与普通服用包芯纱存在很大的差异.实验对不同参数玻璃纤维/涤纶包芯纱的性能进行了研究,结果表明:各存在一个临界摩擦比值,相对应摩擦纺包芯纱的捻度最大、断裂强度最大和抗剥离性最好;但当摩擦比提高到4以上时,条干均匀性变化趋缓.指出可通过后道工序对摩擦纺包芯纱的要求来选择不同工艺参数的摩擦纺包芯纱.这对后道纺织预型件加工和复合材料成型有重要意义.     

回收PET/GF复合材料的研究

采用回收聚对苯二甲酸乙二酯(PET)料与玻璃纤维(GF)和一定量的线性低密度聚乙烯接枝马来酸酐(LLDPE-g-MAH)、恶唑啉进行共混制得回收PET/GF复合材料,并对复合材料的流变性能及物理力学性能进行研究.结果表明,恶唑啉与LLDPE-g-MAH对回收PET/GF复合材料的增粘具有良好的协同作用,当恶唑啉、LLDPE-g-MAH和GF质量分数分别为0.6%、6%和15%时,复合材料力学性能最佳.     

Fabrication of surface-treated BN/ETDS composites for enhanced thermal and mechanical properties

The ceramic/polymer composites based on epoxy-terminated dimethylsiloxane (ETDS) and boron nitride (BN) were prepared for use as thermal interface materials (TIMs). 250 µm-sized BN was used as a filler to achieve high-thermal-conductivity composites. To improve the interfacial adhesion between the BN particles and the ETDS matrix, the surface of BN particles were modified with silica via the sol–gel method with tetraethyl orthosilicate (TEOS). The interfacial adhesion properties of the composites were determined by the surface free energy of the particles using a contact angle test. The surface-modified BN/ETDS composites exhibited thermal conductivities ranging from 0.2 W/m K to 3.1 W/m K, exceeding those of raw BN/ETDS composites at the same weight fractions. Agari׳s model was used to analyze the measured thermal conductivity as a function of the SiO₂-BN concentration. Moreover, the storage modulus of the BN/ETDS composites was found to increase with surface modification of the BN particles.     

Evolution of the morphology and the mechanical properties of ternary PE/PA6/GF composites during annealing

Ternary composites have been prepared via simultaneous melt extrusion of polyethylene (PE), polyamide-6 (PA6) and short glass fibres in a twin screw extruder. If the fibres are compatible with PA6 a network of fibres welded by domains of the minor PA6 phase is build within the matrix (PE) during the processing. Although a small amount of PA6 is added, the presence of the fibres promotes the continuity of this phase. Thus, the ternary mixture resembles the morphology of a co-continuous binary blend. In this paper the stability of the ternary composites upon annealing at temperatures above the melting of PA6 is studied. An increase of the dynamic tensile modulus is observed. Contrary to the behaviour of co-continuous binary blends, for which the properties often deteriorate due to morphology coarsening, in the ternary composites, it leads to the creation of stronger contacts between the fibres and better mechanical performance. This behaviour is accounted for by a recently developed mechanical model.     

Dynamic mechanical properties of cotton/polypropylene commingled composite systems

The dynamic mechanical properties of cotton/polypropylene (PP) commingled composite system was studied with reference to the fiber content, chemical treatments with potassium permanganate and maleic anhydride modified PP, processing conditions and applied frequency. Side by side commingling of matrix and reinforcing fibers was adopted for the fabrication of composite laminates as they provide the shortest melt flow distance during the melting of matrix fibers. This method can also be used for the recycling of textile wastes. The storage modulus was found to increase with the fiber content across a range of temperatures. The loss factor was found to decrease with the increase in fiber content while the glass transition temperature increases. The chemical treatments increase the value of storage modulus. A master curve was constructed and also made a comparison between the experimental results and the theoretically predicted values. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

PET/GF阻燃耐电弧复合材料的研制

制备了ＰＥＴ／ＧＦ阻燃性耐电弧复合材料,发现玻纤和溴－锑阻燃剂会降低ＰＥＴ复合材料的耐电弧性,但选择合适的增容剂可以提高阻燃剂粒子在ＰＥＴ树脂中的分散均匀性,提高了阻燃剂的作用效率,从而减小了阻燃剂的用量,使阻燃对材料耐电弧性的负面影响减小到最小,另外改变加工工艺或添加滑石粉也可提高材料的耐电弧性。     

Fabrication and mechanical properties of SiC platelet reinforced mullite matrix composites

Hot-pressing of mullite and SiC–mullite matrix composites was performed at temperatures and pressures between 1500 and 1650°C and 5 and 15 MPa, respectively. Composites were produced using different precursors; sol–gel derived mullite and kaolinite/α-alumina. The precursor did not strongly affect the optimum density achieved, reaching 97·5% of theoretical for a 20 vol% SiC addition in both cases. The SiC platelet addition impaired densification kinetics in all composites compared to mullite monoliths. Fracture toughness, measured by the indentation strength in bending technique, was marginally higher for the sol–gel precursor material in both monolith and composite. Fracture toughness increased with SiC content for both materials. For example, for the sol-gel precursor material it increased from 2.9±0.1 MPa m^1/2 for the monolith to 3.9±0.1 MPa m^1/2 for the 20 vol% SiC composite. Similarly, hardness increased with SiC addition for both materials, but the hardness of the sol–gel material was greater than that of the kaolinite+α-alumina material for all compositions. The relationship between microstructure and mechanical properties is discussed.     

Flame‐retardant and mechanical properties of rigid polyurethane foam/MRP/mg(OH)2/GF/HGB composites

Some rigid polyurethane foam (RPUF) composites modified with microencapsulated red phosphorus (MRP), magnesium hydrate (Mg(OH)₂), glass fiber (GF), and hollow glass bead (HGB) were prepared. The influence of the MRP, Mg(OH)₂, GF, and HGB on the flame‐retardant, combustion, and mechanical properties of the filled RPUF composites was investigated. The results showed that the flame‐retardant and the combustion properties of the composites were obviously improved, the limiting oxygen index, half burning time and the residual mass/original mass ratio increased with increasing MRP/Mg(OH)₂ weight fraction, especially in case of MRP/Mg(OH)₂ weight fraction of 8 wt %; the carbon monoxide (CO) concentration decreased with increasing MRP/Mg(OH)₂ weight fraction, When the composites were loaded appreciate content of the HGB and the GF, the maximum torque and compressive strength of the composites were improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46551.     

Effects of fiber aggregates on the transverse mechanical behavior of commingled PP–glass fiber composites

In previous articles, mechanical models were proposed to predict the reinforcement effect of polymers by particulates as well as unidirectional fibers over wide ranges of volume fraction of fillers and temperatures. On the basis of image analyses and the definition of representative morphological motifs, these models are able to predict the viscoelastic properties of quasi‐isotropic and unidirectional composites or to extract the behavior of a phase, such as the interphase in filled rubbers or the transcrystalline phase in semicrystalline polymers. In this work, based on a 2D image processing, this approach is extended to predict the viscoelastic properties of commingled PP–glass fiber composites. It is shown that fiber aggregates, composed of fibers and surrounding polymer, might be considered as the reinforcing phase. In addition, the different failure modes of these composites are separated as a function of the volume fraction of fillers or temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3466–3476, 2006     

Study on the crystallization kinetics of PP/GF composites

The crystallization kinetics and morphology of glass fiber-reinforced polypropylene (PP/GF) were investigated in this work. Both isothermal and nonisothermal crystallization behaviors of 90PP/10GF, 80PP/20GF, and 70PP/30GF were examined with a DSC instrument. It was found that the addition of glass fiber would increase the crystallization rate of PP and increase the content of β spherulite, which was most likely formed at temperatures between 390 and 400 K. The morphology of spherulites of PP/GF composites were examined with SEM and a polarized microscope. All experimental observations conformed rather well with the theoretical approach, a dynamic crystallization model, proposed in our previous work. The size of α spherulites of PP would decrease at lower crystallization temperature, or at higher cooling rate, or by adding glass fiber in it.     

Fabrication of hybrid matrix/silane modified carbon fabric composites and study of their mechanical properties

Carbon fiber reinforced polymer composites are an extremely strong and light fiber-reinforced plastics that contains carbon fiber. In the present study, carbon fabrics were treated with various weight percentages of silane and were confirmed by spectral analysis (Fourier transform infrared). The treated carbon fibers were reinforced in hybrid resin (a combination of vinyl ester and epoxy at a ratio of 80:20) by using vacuum-assisted resin transfer mold technique. The composites were tested to know their tensile strength, modulus, flexural strength, modulus, and interlaminar shear strength. The hybrid matrix specimen was also prepared and tested for the mechanical properties and confirmed the miscibility by differential scanning calorimetry and X-ray diffraction. The mechanical properties of hybrid matrix composites (HMCs) were studied by fracture surface morphology with scanning electron microscope. The mechanical properties of the HMCs increased with silane treatment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47695.     

SiCf/SiO2复合材料的制备及界面层对其力学性能的影响

以碳化硅(SiC)纤维为增强体,采用真空浸渍法制备了2.5维连续SiC纤维增韧的SiO2基(SiCf/SiO2)复合材料,研究了SiC纤维编织体上不同的界面层对SiCf/SiO2复合材料力学性能的影响.化学气相渗透(CVI)法制备的热解碳(PyC)和PyC/SiC双层界面层分别使材料的抗弯强度由无界面层的52.2 MPa提高至67.4 MPa和180.3 MPa,但均使材料的韧性降低.用扫描电镜观察了材料的断口形貌,结果表明,PyC和PyC/SiC层不仅提高了材料的抗弯强度,而且增加了基体同纤维间的结合力,使基体有效地将载荷传递给纤维.PyC/SiC层能有效地保护SiC纤维,防止烧结过程中释放出的结晶水对纤维的损伤,有助于提高材料的力学性能.     

PET/GF注塑专用料的研制

通过对原料、工艺参数及配方的筛选,制备了综合性能优异的聚对苯二甲酸乙二酯／玻璃纤维(PET／CF)注塑专用料TS30,对该专用料进行注塑试验,综合考察了制品的结晶性能。结果表明,TS30的结晶速率明显提高,冷结晶温度下降,结晶温度范围变宽,适合于在较低模具温度下注射成型。     

PET/GF复合材料的制备及性能研究

制备了结晶速率快、力学性能优异的玻纤增强聚对苯二甲酸乙二酯（PET／GF）．研究了基体树脂、结晶成核剂、复合结晶促进刑对PET／GF结晶性能和力学性能的影响,结果表明,结晶成核剂和复合结晶促进剂的加入明显降低了PET／GF的玻璃化转变温度,扩大了结晶温度范围,提高了;中击强度。PET／GF的各项性能达到或超过了国内外同类产品的水平.