The effect of paraffin on fiber dispersion and mechanical properties of polyolefin–sawdust composites

This article reports on the influence of the paraffin (PAR) on the wood fiber (WF) dispersion in different polyethylene (low‐density polyethylene, high‐density polyethylene, recycled polyethylene) matrices, as well as on the melt flow behavior and mechanical properties of WF‐reinforced polyethylene (PE) composites. In the presence of paraffin, the composites showed improved tensile and flexural strength and modulus, but lower impact strength and elongation at break. The extent of improvement in mechanical properties depends on paraffin content and type of polyethylene; the most effective paraffin was in LDPE‐based composites. Paraffin‐treated WF showed lower moisture absorption ability in comparison with unmodified wood fiber. The phase segregation process was investigated for PE/PAR blends by DSC method. It was shown that an increase of paraffin concentration in the PE/PAR blend leads to a decrease of PE melting temperature and an increase of paraffin melting temperature; it indicates a net exchange of material from paraffin towards polyethylene. However, generally both components of PE/PAR blends remain immiscible. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2385–2393, 2004     

Experimental investigation of the influence of the compounding process and the composite composition on the mechanical properties of a short flax fiber–reinforced polypropylene composite

Polypropylene (PP) composites containing 20 wt% short flax fibers are prepared, and the process parameters such as throughput, rotational speed, and screw configuration are varied during melt compounding with a corotating intermeshing twin‐screw extruder. The investigations reveal that low rotational speeds, high throughputs, and moderate shear energy inputs by the screw configuration led to an optimum set of mechanical properties. To investigate the influence of different composite compositions on the mechanical properties, composites with fiber contents between 0 and 40 wt% and maleic anhydride‐grafted PP (PP‐g‐MA) contents between 0 and 7 wt% are prepared. Increasing fiber contents enhance the Young's modulus and decrease the elongation at break and the notched impact strength. The tensile strength is barely affected. The addition of PP‐g‐MA increases the tensile strength as well as the elongation at break, whereas the Young's modulus is not influenced. Thus, PP‐g‐MA enhances the adhesion between PP and flax fibers significantly. POLYM. COMPOS., 36:2282–2290, 2015. © 2014 Society of Plastics Engineers     

Effect of fiber pretreatment condition on the interfacial strength and mechanical properties of wood fiber/PP composites

The effect of fiber surface pretreatment on the interfacial strength and mechanical properties of wood fiber/polypropylene (WF/PP) composites are investigated. The results demonstrate that fiber surface conditions significantly influence the fiber–matrix interfacial bond, which, in turn, determines the mechanical properties of the composites. The WF/PP composite containing fibers pretreated with an acid–silane aqueous solution exhibits the highest tensile properties among the materials studied. This observation is a direct result of the strong interfacial bond caused by the acid/water condition used in the fiber pretreatment. Evidence from coupling chemistry, rheological and electron microscopic studies support the above conclusion. When SEBS‐g‐MA copolymer is used, a synergistic toughening effect between the wood fiber and the copolymer is observed. The V‐notch Charpy impact strength of the WF/PP/SEBS‐g‐MA composite is substantially higher than that of the WF/PP composite. The synergistic toughening mechanisms are discussed with respect to the interfacial bond strength, fiber‐matrix debonding, and matrix plastic deformation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1000–1010, 2000     

PP-g-MAH增容改性木粉/PP复合材料的性能研究

以马来酸酐接枝聚丙烯 (PP-g-MAH) 为相容剂,聚丙烯 (PP) 为基体,通过熔融共混法制备了木粉/PP复合材料。研究了 PP-g-MAH 用量对复合材料力学性能及吸水性能的影响; 采用扫描电镜 (SEM) 观察了复合体系的冲击断面形貌。结果表明: 当 PP-g-MAH 的质量分数为 4%时,可以提高添加 35 份木粉复合材料体系的拉伸强度及弯曲强度,比未添加相容剂的分别提高了 49.4%和 16%,而缺口冲击强度仅下降了 9%。SEM 观察证实: PP-g-MAH 的加入有利于提高木粉与 PP 基体的界面相互作用。从吸水率来看,木粉/PP 复合材料的吸水率保持在 0.22% 以下,远低于纯木材。     

废旧聚丙烯编织袋回收料改性应用研究

废旧聚丙烯(PP)编织袋回收料分别与回收聚乙烯(PE)、回收橡胶粉、木粉共混,制备了增韧PP材料、热塑性弹性体和木塑复合材料,采用力学性能测试、SEM和DSC分析等手段对其性能和结构进行了表征。结果表明:随着回收聚乙烯(PE)含量的增加,回收PP/PE共混物的拉伸强度和冲击强度迅速提高;回收PP/橡胶粉共混物中加入聚丙烯接枝马来酸酐(PP-g-MAH)能起到增容的效果,随PP-g-MAH含量的增加,共混物的拉伸强度上升,永久变形减小;在回收PP/木粉复合材料中加入PP-g-MAH后,复合材料的冲击强度明显提高。     

Deformation mechanisms and mechanical properties of modified polypropylene/wood fiber composites

Mechanical properties and deformation mechanisms of polypropylene (PP)/wood fiber (WFb) composites modified with maleated polypropylene as compatibilizer and styrene-butadiene rubber (SBR) as impact modifier have been studied. The addition of maleated polypropylene to the unmodified polypropylene/wood fiber composite enhances the tensile modulus and yield stress as well as the Charpy impact strength. SBR does not cause a drop in the tensile modulus and yield strength because of the interplay between decreasing stiffness and strength by rubber modification and increasing stiffness and strength by good interfacial adhesion between the matrix and fibers. The addition of both maleated polypropylene and rubber to the polypropylene/wood fiber composite does not result in an improvement of effects based on maleated polypropylene and rubber, which includes possible synergism. The deformation mechanisms in unmodified polypropylene/wood fiber composite are matrix brittle fracture, fiber debonding and pullout. A polymeric layer around the fibers created from maleated polypropylene may undergo debonding, initiating local plasticity. Rubber particle cavitation, fiber pullout and debonding were the basic failure mechanisms of rubber-toughened polypropylene/wood fiber composite. When maleated polypropylene was added to this composite, fiber breakage and matrix plastic deformation took place. Polym. Compos. 25:521–526, 2004. © 2004 Society of Plastics Engineers.     

Preparation and characterization of LDPE and PP—Wood fiber composites

Natural fiber reinforced composites is an emerging area in polymer science. These natural fibers are low cost fibers with low density and high specific properties. These are biodegradable and nonabrasive. The natural fiber composites offer specific properties comparable to those of conventional fiber composites. However, in development of these composites, the incompatibility of the fibers and poor resistance to moisture often reduce the potential of natural fibers, and these draw backs become critical issue. Wood‐plastic composites (WPC) are a relatively new class of materials and one of the fastest growing sectors in the wood composites industry. Composites of wood in a thermoplastic matrix (wood–plastic composites) are considered a low maintenance solution to using wood in outdoor applications. WPCs are normally made from a mixture of wood fiber, thermoplastic, and small amounts of process and property modifiers through an extrusion process. In this study, Wood–plastic composites (WPC) are produce by adding a maleic anhydride modified low density polyethylene coupling agent to improve interfacial adhesion between the wood fiber and the plastic. Mixing is done with twin screw extruder. Subsequently, tensile strength, the modulus of elasticity, % elongation, hardness, Izod impact strength, melt flow index (MFI), and heat deflection temperature (HDT) are determined. Thermal transition temperatures and microstructure are determined with DSC and SEM, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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。     

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     

Silica‐filled polypropylene composites: The effect of ethylene diamine dilaurate and maleic anhydride grafted polypropylene on mechanical properties,water absorption,morphology, and thermal properties

The effect of two compatibilizers, i.e. ethylene diamine dilaurate (EDD) and maleic anhydride grafted polypropylene (MAPP) on the mechanical properties, water absorption, morphology, and thermal properties of silica‐filled polypropylene (PP/Sil) composites were studied. The results show that the tensile, impact and flexural strengths (up to 2 php), Young's modulus, and elongation at break (Eb) increased with increasing EDD content. However, increasing MAPP content increases the tensile strength, Young's modulus, impact and flexural strengths, and water absorption resistance. At a similar compatibilizer content, EDD exhibits higher Eb, impact and flexural strengths but lowers tensile strength, Young's modulus, and water absorption resistance compared with MAPP. Scanning electron microscopy study of tensile fractured surfaces exhibits the evidence of better silica‐PP adhesion with MAPP and EDD compared with the similar composites but without compatibilizer. Fourier transform infra red spectra provide an evidence of interaction between EDD or MAPP with PP/Sil composites. Termogravimetry analysis results indicate that the addition of EDD or MAPP slightly increases the thermal stability of PP/Sil composites. Differential scanning calorimetry also indicates that PP/Sil composites with EDD or MAPP have higher heat fusion (ΔH_f(com)) and crystallinity (X_com) than similar composites but without compatibilizer. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Influence of organically modified nanoclay on the performance of pineapple leaf fiber‐reinforced polypropylene nanocomposites

Polypropylene/Pine apple leaf fiber (PP/PALF)‐reinforced nanocomposites were fabricated using melt blending technique in a twin‐screw extruder (Haake Rheocord 9000). Variation in mechanical properties, crystallization behavior, water absorption, and thermal stability with the addition of nanoclay in PP/PALF composites were investigated. It was observed that the tensile, flexural, and impact properties of PP increase with the increase in fiber loading from 10 to 30 wt %. Composites prepared using 30 wt % PALF and 5 wt % MA‐g‐PP exhibited optimum mechanical performance with an increase in tensile strength to 31%, flexural strength to 45% when compared with virgin PP. Addition of nanoclay results in a further increase in tensile and flexural strength of PP/PALF composites to 20 and 24.3%, which shows intercalated morphology. However, addition of nanoclay does not show any substantial increase in impact strength when compared with PP/PALF composites. Dynamic mechanical analysis tests revealed an increase in storage modulus (E′) and damping factor (tan δ), confirming a strong influence between the fiber/nanoclay and MA‐g‐PP. Differential scanning calorimetry, thermogravimetric analysis thermograms also showed improved thermal properties when compared with the virgin matrix. TEM micrographs also showed few layers of agglomerated clay galleries along with mixed nanomorphology in the nanocomposites. Wide angle X‐ray diffraction studies indicated an increase in d‐spacing from 22.4 Å in Cloisite 20A to 40.1 Å in PP/PALF nanocomposite because of improved intercalated morphology. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

An investigation of the interfacial adhesion between reclaimed newspaper and recycled polypropylene composites through the investigation of their mechanical properties

The effects of different parameters (e.g. method of defibration of newspaper; size of the fiber; type and concentrations of coupling agents, impact modifiers, and fire retardants) on the mechanical properties of old newspaper fiber-filled recycled polypropylene (PP) have been evaluated. Statistical methods were applied to determine the effects of variables on the tensile strength, Young's modulus, tensile toughness, and impact strength. Statistical analysis revealed that the composites based on newspaper fiber prepared by mechanical defibration showed a better tensile strength compared with those prepared by the steam explosion process, while the latter type of fiber outperformed the former as far as the other mechanical properties are concerned. In the presence of maleic anhydride grafted PP (MPP) and the initiator dicumyl peroxide (DCPO), the tensile strength of the composites increased with increasing fiber loading and fiber size. Moreover, both the tensile strength and the modulus increased with an increase in the concentrations of MPP and DCPO, even in the presence of an impact modifier and fire retardants for surface-modified newspaper-filled composites. Since the tensile strength of short fiber reinforced composites is strongly dependent of the degree of adhesion between the fiber and matrix, the experimental results suggest that either one of these (MPP and DCPO) or both act as the interfacial bonding agent to develop a strong interphase between old newspaper fiber and recycled PP.     

Fabrication and mechanical properties of glass fiber‐reinforced wood plastic hybrid composites

To fully utilize the resource in the municipal solid waste (MSW) and improve the strength and toughness of wood plastic composites, glass fiber (GF)‐reinforced wood plastic hybrid composites (GWPCs) were prepared through compounding of recycled high‐density polyethylene (HDPE) from MSW, waste wood fibers, and chopped GF. Mechanical tests of GWPCs specimens with varying amounts of GF content were carried out and the impact fractured surface of GWPCs was observed through scanning electron microscope (SEM). The tensile strength of GWPCs and the efficiency coefficient values were predicted by Kelly‐Tyson method. The results indicated that the tensile strength and impact strength of GWPCs could be improved simultaneously by adding type L chopped GF (L‐GF), and would be dropped down when type S chopped GF (S‐GF) was included. The tensile strength of GWPCs was well accordant with the experimental result. The efficiency coefficient values of S‐GF and L‐GF are ?0.19 and 0.63, respectively. Inspection of SEM micrographs indicated that L‐GF had achieved full adhesion with the plastic matrix through addition of maleic anhydride‐g‐polyethylene. The main fracture modes of GWPCs included pullout of GF, broken of matrix, and interfacial debonding. Because of the synergistic effects between hybrid components in GF/wood fiber/HDPE hybrid system, a special 3D network microstructure was formed, which was the main contribution to the significant improvement in the tensile strength and impact strength of L‐GF‐reinforced hybrid composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical properties of composites from sawdust and recycled plastics

Mechanical properties of wood plastic composites (WPCs) manufactured from sawdust and virgin and/or recycled plastics, namely high density polyethylene (HDPE) and polypropylene (PP), were studied. Sawdust was prepared from beech industrial sawdust by screening to the desired particle size and was mixed with different virgin or recycled plastics at 50% by weight fiber loading. The mixed materials were then compression molded into panels. Flexural and tensile properties and impact strength of the manufactured WPCs were determined according to the relevant standard specifications. Although composites containing PP (virgin and recycled) exhibited higher stiffness and strength than those made from HDPE (virgin and recycled), they had lower unnotched impact strengths. Mechanical properties of specimens containing recycled plastics (HDPE and PP) were statistically similar and comparable to those of composites made from virgin plastics. This was considered as a possibility to expand the use of recycled plastics in the manufacture of WPCs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3641–3645, 2006     

Biopolyamide hybrid composites for high performance applications

This study focuses on the performance characteristics of wood/short carbon fiber hybrid biopolyamide11 (PA11) composites. The composites were produced by melt‐compounding of the fibers with the polyamide via extrusion and injection molding. The results showed that mechanical properties, such as tensile and flexural strength and modulus of the wood fiber composites were significantly higher than the PA11 and hybridization with carbon fiber further enhanced the performance properties, as well as the thermal resistance of the composites. Compared to wood fiber composites (30% wood fiber), hybridization with carbon fiber (10% wood fiber and 20% carbon fiber) increased the tensile and flexural modulus by 168% and 142%, respectively. Izod impact strength of the hybrid composites exhibited a good improvement compared to wood fiber composites. Thermal properties and resistance to water absorption of the composites were improved by hybridization with carbon fiber. In overall, the study indicated that the developed hybrid composites are promising candidates for high performance applications, where high stiffness and thermal resistance are required. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43595.     

High Stiffness Natural Fiber‐Reinforced Hybrid Polypropylene Composites

Abstract

Natural fibers are potentially a high‐performance non‐abrasive reinforcing fiber source. In this study, pulp fibers [including bleached Kraft pulp (BKP) and thermomechanical pulp (TMP)], hemp, flax, and wood flour were used for reinforcing in polypropylene (PP) composite. The results show that pulp fibers, in particular, TMP‐reinforced PP has the highest tensile strength, possibly because pulp fibers were subjected to less severe shortening during compounding, compared to hemp and flax fiber bundles. Maleic‐anhydride grafted PP (MAPP) with high maleic anhydride groups and high molecular weight was more effective in improving strength properties of PP composite as a compatiblizer. Coupled with 10% glass fiber, 40% TMP reinforced PP had a tensile strength of 70 MPa and a specific tensile strength comparable to glass fiber reinforced PP. Thermomechanical pulp was more effective in reinforcing than BKP. X‐ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used to aid in the analysis. Polypropylene with high impact strength was also used in compounding to improve the low‐impact strength prevalent in natural fiber‐reinforced PP from injection molding.     

Effect of chemical treatments of wood fibers on the physical strength of polypropylene based composites

Wood plastic composites attract great attention in various applications. Chemical modification of the wood fiber with NaOH and various coupling agents was performed for wood fiber composites. Wood fibers treated with NaOH, APTES, TEVS, and BC coupling agents were compounded with PP matrix for measuring physical properties. All those chemical treatments increased physical properties much compared to the untreated case because of the elimination of impurities by NaOH treatment and because of the introduction of compatible molecular structure onto the wood fiber surfaces. Especially, the TEVS case showed the best tensile strength, and it could be attributed to the chain structure having double bond of the molecules for high compatibility with PP matrix. The SEM morphology also demonstrated increased adhesion between wood fibers and PP matrix with chemical treatments. The adhesion between wood fiber and PP matrix would be a key parameter in achieving high physical properties of the composite materials.     

Incorporation of epoxidized soybean oil as co‐matrix in epoxy resin toward developing plastisol/particulate toughened glass fiber composites

Epoxidized soybean oil was incorporated as a co‐matrix into an epoxy resin, and the hybrid resin system was used for preparing glass fiber‐reinforced composites. Effect of addition of poly(vinyl chloride) plastisol and selected particulate fillers (fly ash and wood flour) to epoxy/epoxidized soybean oil matrix on mechanical and water uptake properties of glass fiber‐reinforced composites were studied. Fourier transform infrared spectroscopy was used to reveal the curing state of these composites. It was observed that tensile strengths and moduli decreased with the inclusion of all additives. However, addition of poly(vinyl chloride) plastisol, fly ash, and wood flour particulate fillers showed significant increase in impact strengths compared with neat epoxy composite in a synergistic manner. Water uptake results of the composites were found to be in good agreement with ? OH peak intensities obtained from Fourier transform infrared spectroscopy. Finally, acousto‐ultrasonic nondestructive technique was successfully used to assess damage states and to relate stress wave factors with tensile strength properties of modified epoxy‐based glass fiber composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40586.     

Creep fatigue in engineered wood fiber and plastic compositions

Creep behaviour of unmodified and functionally modified thermoplastic‐wood fibre composites was studied. For PVC, PE and PP‐based composites creep is strongly dependent on the amount of load, time and temperature. A small rise in the temperature above ambient temperature increased creep significantly for PVC‐woodfiber composites. Instantaneous creep resistance of woodfibre‐filled PP is higher than that of PE‐based composites. PP and PE‐based wood composites were modified with maleic and maleimide compounds. Maleic or maleimide modification of woodfibre improved transient creep behaviour of PP‐woodfibre composite but it did not show practically any effect on instantaneous creep. A mathematical model has been proposed to predict creep behaviour of PVC, PP an PE‐based wood fiber composites. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 260–268, 2000     

玄武岩纤维对PE-HD/竹粉复合材料增强增韧研究

本文通过熔融共混方法制备高密度聚乙烯(HDPE)/竹粉/玄武岩纤维(FB)共混物,研究了竹粉和玄武岩纤维对HDPE的拉伸强度、弯曲强度、冲击强度和耐热性能的影响;结果表明,加入竹粉,HDPE/竹粉复合材料的拉伸强度和冲击强度显著下降,但是弯曲强度有所上升,材料显脆性;但是当玄武岩纤维部分取代竹粉后,HDPE/竹粉/玄武岩纤维复合材料的拉伸强度、弯曲强度和冲击强度得到大幅度增加,体现较好的协同效应;结果证实玄武岩纤维是木塑/竹塑复合材料较好的增强增韧纤维材料。