Mechanical properties and morphology of polypropylene composites. III. Short glass fiber reinforced elastomer modified polypropylene

The impact strength and rigidity of polypropylene composites can be significantly improved by application of short glass fibers instead of mineral fillers in elastomer-modified polypropylene. The properties of such composites are strongly dependent on the adhesive forces at the fiber-matrix interface. Poor adhesion results in interfacial fracture solely by fiber-matrix debonding, as evidenced by scanning electron microscopy on the fracture surfaces. This is accompanied by relatively low impact strengths. By contrast, increased adhesion leads to fracture not only by fiber-matrix debonding, but also by crack propagation through the elastomeric phase at the fiber surface. This mechanism is thought to be responsible for a remarkable increase of the impact strength. Appropriate compositions of polypropylene, glass fiber, and elastomer resulted in composite properties similar to, or even better than, those of a typical acrylonitrile-butadiene-styrene copolymer. The lengths of the fibers recovered from the test specimens were somewhat smaller than the critical fiber lengths as calculated by simple shear lag theory. The properties of the present composites should thus be regarded as minima, rather than as potential maxima. This suggests that current composites may be suitable for engineering applications.     

Impact fracture behavior of PP/EPDM/glass bead ternary composites

The effects of glass bead filler content and surface treatment of the glass with a silane coupling agent on the room temperature impact fracture behavior of polypropylene (PP)/ethylene‐propylene‐diene monomer copolymer (EPDM)/glass bead(GB) ternary composites were determined. The volume fraction of EPDM was kept constant at 10%. The impact fracture energy and impact strength of the composites increased with increasing volume fraction of glass beads (?_g). Surface pretreatment of the glass beads had an insignificant effect on the impact behavior. For a fixed filler content, the best impact strength was achieved when untreated glass beads and a maleic anhydride modified EPDM were used. The impact strength exhibited a maximum value at ?_g=15%. Morphology/impact property relationships and an explanation of the toughening mechanisms were developed by comparing the impact properties with scanning electron micrographs of fracture surfaces.     

Injection‐molded short hemp fiber/glass fiber‐reinforced polypropylene hybrid composites—Mechanical,water absorption and thermal properties

Natural fiber‐based thermoplastic composites are generally lower in strength performance compared to thermoset composites. However, they have the advantage of design flexibility and recycling possibilities. Hybridization with small amounts of synthetic fibers makes these natural fiber composites more suitable for technical applications such as automotive interior parts. Hemp fiber is one of the important lignocellulosic bast fiber and has been used as reinforcement for industrial applications. This study focused on the performance of injection‐molded short hemp fiber and hemp/glass fiber hybrid polypropylene composites. Results showed that hybridization with glass fiber enhanced the performance properties. A value of 101 MPa for flexural strength and 5.5 GPa for the flexural modulus is achieved from a hybrid composite containing 25 wt % of hemp and 15 wt % of glass. Notched Izod impact strength of the hybrid composites exhibited great enhancement (34%). Analysis of fiber length distribution in the composite and fracture surface was performed to study the fiber breakage and fracture mechanism. Thermal properties and resistance to water absorption properties of the hemp fiber composites were improved by hybridization with glass fibers. Overall studies indicated that the short hemp/glass fiber hybrid polypropylene composites are promising candidates for structural applications where high stiffness and thermal resistance is required. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2432–2441, 2007     

Effect of macromolecular coupling agent on the property of PP/GF composites

Silane‐grafted polypropylene manufactured by a reactive grafting process was used as the coupling agent in polypropylene/glass‐fiber composites to improve the interaction of the interfacial regions. Polypropylene reinforced with 30% by weight of short glass fibers was injection‐molded and the mechanical behaviors were investigated. The results indicate that the mechanical properties (tensile strength, tensile modulus, flexural strength, flexural modulus, and Izod impact strength) of the composite increased remarkably as compared with the noncoupled glass fiber/polypropylene. SEM of the fracture surfaces of the coupled composites shows a good adhesion at the fiber/matrix interface: The fibers are coated with matrix polymer, and a matrix transition region exists near the fibers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1537–1542, 1999     

Mechanical properties of poly(vinyl chloride)/wood flour/glass fiber hybrid composites

Short glass fibers were added to poly(vinyl chloride) (PVC)/wood flour composites as reinforcement agents. Unnotched and notched impact strength of PVC/wood flour/glass fiber hybrid composites could be increased significantly without losing flexural properties by adding type L glass fibers and over 40% of PVC. There was no such improvement when using type S glass fiber. The impact strength of hybrid composites increased along with the increment of the type L glass fiber content at a 50% PVC content. At high PVC contents, impact fracture surfaces were characterized by wood particle, glass fiber breakage and pullout, whereas interfacial debonding was the dominant fracture mode at higher filler concentrations. The significant improvement in impact strength of hybrid composites was attributed to the formation of the three‐dimensional network glass fiber architecture between type L glass fibers and wood flour.     

Experimental investigation on the influence of the composition on the morphology and the mechanical properties of short glass fiber‐reinforced polypropylene nanocomposites

Polypropylene composites containing 0–5 wt% layered silicate and 0–30 wt% short glass fibers are prepared by melt compounding. To investigate the influence of different compositions on the mechanical properties of short glass fiber‐reinforced polypropylene nanocomposites, materials with various filler contents are prepared. At a glass fiber content of 10 wt% Young's modulus of the layered silicate‐containing composites decreases by around 30% compared to conventional glass fiber‐reinforced polypropylene. But at higher glass fiber loadings, an increasing modulus of up to 10% is observed. However, the addition of layered silicate results in large decreases of the tensile and the notched impact strength. A maleic anhydride‐grafted polypropylene enhances Young's modulus and the tensile strength. © 2012 Society of Plastics Engineers     

玻纤增强PP复合材料的制备及其性能研究

通过螺杆挤出法制备了玻璃纤维增强聚丙烯(GFRPP)复合材料。利用电子万能试验机对复合材料的力学性能进行了测量,并对实验结果进行了分析。结果表明:随着GF用量的增加,GFRPP复合材料的拉伸强度和冲击强度也相应增大,且12 mm长玻纤的复合材料比6 mm的高;随着GF用量的增加,GFRPP复合材料的断裂伸长率呈先增大再减小的趋势,且12 mm长玻纤的复合材料比6 mm的小。     

Physico-mechanical studies of wood fiber reinforced composites

Wood polypropylene composites (WPC) of different compositions (30, 40, and 50%) have been prepared using maleic anhydride–polypropylene copolymer of different percentage (5 and 10% relative to their wood fiber content). Tensile, flexural, fracture toughness, and impact test of the prepared WPC were carried out. From the results, it is observed that the hard wood fiber–polypropylene composites, by using maleated polypropylene (MAH-PP), show comparatively better performance to soft wood fiber–polypropylene composites. Tensile strength and charpy impact strength have been increased to a maximum of 50 and 20%, respectively. The damping index has been decreased by 60% when 10% of MAH-PP has been used. Water absorption and scanning electron microscopy of the composites are also investigated.     

Influence of interfacial adhesion on the structural and mechanical behavior of PP‐banana/glass hybrid composites

Hybrid composites of polypropylene (PP), reinforced with short banana and glass fibers were fabricated using Haake torque rheocord followed by compression molding with and without the presence maleic anhydride grafted polypropylene (MAPP) as a coupling agent. Incorporation of both fibers into PP matrix resulted in increase of tensile strength, flexural strength, and impact strength upto 30 wt% with an optimum strength observed at 2 wt% MAPP treated 15 wt% banana and 15 wt% glass fiber. The rate of water absorption for the hybrid composites was decreased due to the presence of glass fiber and coupling agent. The effect of fiber loading in presence of coupling agent on the dynamic mechanical properties has been analyzed to investigate the interfacial properties. An increase in storage modulus (E′) of the treated‐composite indicates higher stiffness. The loss tangent (tan δ) spectra confirms a strong influence of fiber loading and coupling agent concentration on the α and β relaxation process of PP. The nature of fiber matrix adhesion was examined through scanning electron microscopy (SEM) of the tensile fractured specimen. Thermal measurements were carried out through differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA), indicated an increase in the crystallization temperature and thermal stability of PP with the incorporation of MAPP‐treated banana and glass fiber. POLYM. COMPOS., 31:1247–1257, 2010. © 2009 Society of Plastics Engineers     

The morphology of fracture surfaces and mechanical properties of composites of polypropylene with glass fibers having different interface adhesion

For composites polypropylene–short glass fibers having different interface adhesion, correlation has been proved to exist between the morphology of fracture surfaces, the temperature dependence of impact strength, and the deformational and fracture behavior in tensile loading. The results are interpreted in terms of the mechanism of distortion plasticity for unfilled PP and for filled PP having weak interface adhesion, and on the basis of dilatation plasticity for filled polypropylene with a higher interface adhesion. The transition from the distortion to the dilatation mechanism can be seen in fracture surfaces after tensile destruction in composites possessing a higher interface adhesion.     

Drop weight impact and work of fracture of short glass fiber reinforced polypropylene composites toughened with elastomer

Short glass fiber (SGF) reinforced polypropylene composites toughened with styrene‐ethylene butylene‐styrene (SEBS) or maleated SEBS (SEBS‐g‐MA) triblock copolymer were injection molded. Charpy drop‐weight impact properties and the impact essential work of fracture (EWF) of the SGF/SEBS/PP and SGF/SEBS‐g‐MA/PP hybrids were investigated. Drop‐weight impact results revealed that the SGF/SEBS/PP hybrid exhibits higher impact strength than the SGF/SEBS‐g‐MA/PP hybrid at low impact speeds. This was derived from the pull‐out of fibers from the SGF/SEBS/PP hybrid. At high impact speeds, the impact strength of the SGF/SEBS‐g‐MA/PP hybrid was slightly higher than that of the SGF/SEBS/PP hybrid. Impact EWF measurements showed that the hybrids only exhibit specific essential work (W_e) at a high impact speed of 3 ms⁻¹. The non‐essential work does not occur in the hybrids under high impact rate loading conditions. Moreover, SEBS or SEBS‐g‐MA addition was beneficial in enhancing the high‐rate specific essential work of the SGF/SEBS/PP and SGF/SEBS‐g‐MA/PP hybrid composites.     

高强高韧GF／PP复合材料的研究

通过在短玻(GF)增强聚丙烯(PP)中添加聚烯烃弹性体(POE),并用马来酸酐对PP进行接枝交联的方法, 制备了高冲击韧性GF／PP复合材料。在该材料中,短切玻璃纤维的加入大幅度提高了材料的拉伸、弯曲强度,而POE 则通过产生形变等方式,提高了材料的冲击韧性;在其中加入马来酸酐接枝聚丙烯增加界面结合力,可使GF／PP／POE 复合体系表现出良好的综合力学性能,其拉伸强度为51．9 MPa,弯曲强度为68．1MPa,冲击韧性为44．2 kJ／m2。     

ABS/SMA/GF复合材料的制备及性能

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)及玻璃纤维(GF)为原料,以苯乙烯-马来酸酐共聚物(SMA)作为界面相容剂,研究界面相容剂对玻璃纤维增强ABS复合材料力学性能及界面粘接的影响.结果表明:加入SMA玻纤增强ABS复合材料的力学性能明显提高;随着玻纤质量分数增加,复合材料的拉伸强度、弯曲强度均逐渐增加,冲击强度下降.     

玻纤增强聚丙烯木塑复合材料的性能研究

分别以聚丙烯(PP)、聚乙烯(PE)、玻纤增强PP/PE为基体材料,通过挤出成型制备了木塑复合材料(WPC)。研究表明,玻纤能够有效地提高WPC的性能,以玻纤增强PP/PE为基体制备的WPC的冲击强度、拉伸强度、弯曲强度、弯曲弹性模量分别达到4.58 kJ/m2,19 MPa,30.8 MPa,3520 MPa,性能优于以PP或PE为基体制备的WPC。     

Effect of impregnation time on performance of long glass fiber‐reinforced polypropylene composites

Long glass fiber (LGF)‐reinforced polypropylene (PP) composites were prepared using self‐designed impregnation device. Effects of impregnation time on mechanical properties, crystallization, dynamic mechanical properties, and morphology of PP/LGF composites were investigated. The experiment results demonstrate that the excellent tensile strength, Notched Izod impact strength was 152.9 MPa, 31.2 KJ/m², respectively, and the stiffness of PP/LGF composites was higher, when the impregnation time was 7.03 s. The excellent interfacial adhesion between PP and glass fiber indicates that PP/LGF composites possess the outstanding mechanical properties. The impregnation time scarcely influenced thermal properties of PP/LGF composites. J. VINYL ADDIT. TECHNOL., 24:174–178, 2018. © 2016 Society of Plastics Engineers     

聚丙烯/马来酸酐接枝聚丙烯/环氧树脂/玻璃纤维复合材料的制备及其性能研究

通过双螺杆挤出机制备了聚丙烯/马来酸酐接枝聚丙烯/环氧树脂/玻璃纤维（PP/PP-g-MAH/EP/GF）复合材料,并研究了PP-g-MAH含量、EP含量及固化剂对复合材料力学性能的影响。结果表明,PP-g-MAH含量为10份,含有固化剂EP的含量为3份时,复合材料的综合力学性能最佳;与不加EP的复合材料相比,其拉伸强度、弯曲强度、冲击强度分别提高了41 %、47 %、86 %。扫描电子显微镜分析表明,EP的加入明显改善了GF和PP基体的黏结强度。     

玻纤增强PP热塑性片材的制备及力学性能研究

采用熔融浸渍法制备了玻璃纤维毡增强聚丙烯（PP）热塑性复合片材；通过在PP中加入复合改性PP改善了基体与增强纤维间的相容性；考察了相容剂、PP种类及玻纤毡种类对复合片材的影响。结果表明，相容剂的加入可使复合片材的拉伸强度提高29％、拉伸模量提高23％、弯曲强度提高42％、弯曲模量提高25％；高熔体质量流动速率PP可使片材的弯曲与冲击性能进一步改善。连续玻纤毡和长玻纤毡增强PP复合片材，前者综合力学性能良好，而后者则冲击强度较弱、弯曲性能加强。     

硅灰石与连续玻璃纤维毡组合增强聚丙烯的力学性能

采用硅灰石与连续玻璃纤维毡组合增强聚丙烯,研究了硅灰石的含量,玻璃纤维毡的面密度、基体树脂的性质及界面改性等对材料力学性能的影响。结果表明：采用硅灰石与连续玻璃纤维毡组合增强,可提高复合材料的拉伸、弯曲强度及模量,但过高的硅灰石含量,会导致拉伸及弯曲强度下降,材料的力学性能随着所用玻璃纤维毡面密度的增大而显著提高,采用偶联剂对硅灰石进行处理及在基体聚丙烯中添加功能化聚丙烯,可改善界面结合、提高材料性能,随着功能化聚丙烯含量的增加,材料的拉伸、弯曲强度及模量有所提高,但含量过高时,会引起材料冲击强度的下降;组合增强材料的性能与基体树脂本身的力学性能密切相关,同时还受基体树脂熔体流动性的影响。     

Mechanical properties of injection molded long fiber polypropylene composites,Part 2: Impact and fracture toughness

This study describes the effect of fiber length and compatibilizer content on notched izod impact and fracture toughness properties. Long fiber polypropylene (LFPP) pellets of different sizes were prepared by extrusion process using a new radial impregnation die, and subsequently, pellets were injection molded as described in previous publication 1 . The content of glass fiber reinforcement was maintained same for all compositions. Maleic‐anhydride grafted polypropylene (MA‐g‐PP) was chosen as a compatibilizer to increase the adhesion between glass fiber and PP matrix and its content was maintained at 2 wt%. Notched izod impact property was studied for LFPP composites prepared with and without compatibilizer for different pellet sizes. Failure mechanism due to sudden impact was analyzed with scanning electron micrographs and was correlated with impact property of LFPP composites. Fracture and failure behavior of injection molded LFPP composite were studied and relationship between fracture toughness and microstructure of LFPP composite was analyzed. The microstructure of the composites was characterized by the dimensionless reinforcing effectiveness parameter, which accounts for the influence of fiber layer structure, fiber alignment, fiber volume fraction, fiber length distribution, and aspect ratio. Matrix stress condition factor and energy absorption ratio were determined for LFPP composites prepared with and without compatibilizer. Failure mechanism of both the matrix and fiber, revealed with SEM images, were discussed. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

HDPE reinforced with glass fibers: Rheology,tensile properties,stress relaxation,and orientation of fibers

Glass fiber‐reinforced high‐density polyethylene of varying concentrations was mixed with ethylene copolymer and maleic anhydride‐grafted polypropylene (coupling agents) separately. The viscosity, tensile strength, and stress relaxation properties of the composites were investigated. The orientation and anisotropy of glass fibers were studied using micro computed tomography scanner. It was found out that the orientation and anisotropy of fiber are strongly affected by the increase in glass fiber concentration. POLYM. COMPOS., 35:2159–2169, 2014. © 2014 Society of Plastics Engineers