Nanosilica as dry bonding system component and as reinforcement in short nylon‐6 fiber/natural rubber composite

Nanoscale silica was synthesized by acid hydrolysis of sodium silicate using dilute hydrochloric acid under controlled conditions. The synthesized silica was characterized by SEM, BET adsorption, and XRD. The particle size of silica was calculated to be 13 nm from the XRD results and the surface area was found to be 295 m²/g by BET method. This synthesized nanosilica was used in place of conventional silica in HRH (hexamethylenetetramine, resorcinol and silica) bonding system for natural rubber/Nylon‐6 short fiber composite. Nanosilica was also used as reinforcing filler in natural rubber/Nylon‐6 short fiber hybrid composite. Mechanical, thermal, and dynamic mechanical properties of the composites were evaluated. The introduction of the nanosilica in hybrid composites improved the tensile strength, modulus, and tear strength through improved interaction with the matrix which is facilitated by the higher surface area. Abrasion loss and hardness were also better for the nanosilica composites. Resilience and compression set were adversely affected. The hybrid composites showed anisotropy in mechanical properties. Peak rate of thermal decomposition decreased and temperature of initiation of thermal degradation increased with silica content, indicating improved thermal stability of the hybrid composites. The storage modulus and loss modulus showed two‐stage dependence on frequency at higher fiber loading. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical,thermal, and morphological properties of maleic anhydride‐g‐polypropylene compatibilized and chemically modified banana‐fiber‐reinforced polypropylene composites

Composites were prepared with chemically modified banana fibers in polypropylene (PP). The effects of 40‐mm fiber loading and resin modification on the physical, mechanical, thermal, and morphological properties of the composites were evaluated with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Infrared (IR) spectroscopy, and so on. Maleic anhydride grafted polypropylene (MA‐g‐PP) compatibilizer was used to improve the fiber‐matrix adhesion. SEM studies carried out on fractured specimens indicated poor dispersion in the unmodified fiber composites and improved adhesion and uniform dispersion in the treated composites. A fiber loading of 15 vol % in the treated composites was optimum, with maximum mechanical properties and thermal stability evident. The composite with 5% MA‐g‐PP concentration at a 15% fiber volume showed an 80% increase in impact strength, a 48% increase in flexural strength, a 125% increase in flexural modulus, a 33% increase in tensile strength, and an 82% increase in tensile modulus, whereas the heat deflection temperature increased by 18°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

凹凸棒石／茂金属聚烯烃复合材料的结构与性能

研究了加工温度、偶联剂改性、增容剂KEOC－g－MAH等因素对凹凸棒石（AT）／聚烯烃热塑性弹性体（EOC）复合材料性能的影响。结果表明，加工温度越高，熔体粘度越低，AT的分散越不好；加入较高接枝率的增容剂EOC－g－MAH，用KH550处理的凹凸棒石对EOC的补强效果最好。当经KH550处理的凹凸棒石为10份，接枝率为0．89％的EOC－g－MAH为15份时，复合材料的100％拉伸模量、拉伸强度和撕裂分别比EOC弹性体提高104％、65％、25％。通过SEM、DSC、TEM分析表明，制备的AT／EOC复合材料是凹凸棒石微米尺寸分散的复合材料，AT未能分散形成纳米单晶，并且AT对EOC的结晶、熔融无明显影响。     

Preparation and properties of polypropylene/org-attapulgite nanocomposites

Polypropylene (PP)/org-attapulgite (ATP) nanocomposites were prepared by melt blending in a mixer apparatus. Org-attapulgite was attained by silane coupling agent modification first and then graft-polymerization with butyl acrylate. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to assess the clay morphology and the dispersion of the org-attapulgite, respectively. The changes of crystalline structure for PP nanocomposites were characterized by X-ray diffraction (XRD). The mechanical properties of PP/attapulgite nanocomposites were studied through tensile and impact tests. The thermal and dynamic mechanical properties were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The strength and stiffness of PP/org-ATP nanocomposites were both improved significantly in the presence of organic attapulgite. In addition, the incorporation of org-ATP also gave rise to an increase of the storage modulus and the changes of the glass transition temperature for PP composites. TEM and XRD results revealed the addition of attapulgite did not change the crystal structure of PP, however org-attapulgite acted as nucleating agents for the crystallization of PP.     

Enhancement of PVC/ENR blend properties by poly(methyl acrylate) grafted oil palm empty fruit bunch fiber

Effect of oil palm empty fruit bunch (OPEFB) fiber and poly(methyl acrylate) grafted OPEFB on several mechanical properties of poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends were studied. The composites were prepared by mixing the fiber and the PVC/ENR blends using HAKEE Rheomixer at the rotor speed of 50 rpm, mixing temperature 150°C, and mixing period of 20 min. The fiber loadings were varied from 0 to 30% and the effect of fiber content in the composites on their ultimate tensile strength (UTS), Young's modulus, elongation at break, flexural modulus, hardness, and impact strength were determined. An increasing trend was observed in the Young's modulus, flexural modulus, and hardness with the addition of grafted and ungrafted fiber to the PVC/ENR blends. However the impact strength, UTS, and elongation at break of the composites were found to decrease with the increase in fiber loading. An increase in elongation at break and UTS and decrease in the flexural and Young's modulus was observed with the addition of PMA‐g‐OPEFB fiber compared to ungrafted fiber. This observation indicates that grafting of PMA onto OPEFB impart some flexibility to the blend. The morphology of cryogenically fractured and tensile fracture surfaces of the composites, examined by a scanning electron microscope shows that the adhesion between the fiber and the matrix is improved upon grafting of the OPEFB fiber. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polylactide,nanoclay, and core–shell rubber composites

Three types of composites, namely, polylactide (PLA)/nanoclay, PLA/core–shell rubber, and PLA/nanoclay/core–shell rubber, were melt compounded via a corotating twin‐screw extruder. The effects of two types of organically modified montmorillonite nanoclays (i.e., Cloisite®30B and 20A), two types of core (polybutylacrylate)–shell (polymethylmethacrylate) rubbers (i.e., Paraloid EXL2330 and EXL2314), and the combination of nanoclay and rubber on the mechanical and thermal properties of the composites were investigated. According to X‐ray diffraction and transmission electron microscopy analyses, both types of PLA/5 wt% nanoclay composites had an intercalated morphology. In comparison with pure PLA, both types of PLA/5 wt% nanoclay composites had an increased modulus, similar impact strength, slightly reduced tensile strength, and significantly reduced strain at break. On the other hand, PLA/EXL2330 composites with a rubber loading level of 10 wt% or higher had a much higher impact strength and strain at break, but a lower modulus and strength when compared with pure PLA. The simultaneous addition of 5 wt% nanoclay (Cloisite®30B) and 20 wt% EXL2330 resulted in a PLA composite with a 134% increase in impact strength, a 6% increase in strain at break, a similar modulus, and a 28% reduction in tensile strength in comparison with pure PLA. POLYM. ENG. SCI. 46:1419–1427, 2006. © 2006 Society of Plastics Engineers     

Mica reinforced nylon‐6: Effect of coupling agents on mechanical,thermal, and dielectric properties

The effects of applying titanate (TYZOR® TPT) and silane (DYNASYLAN VTMO) coupling agents to wet ground muscovite mica in nylon‐6 composites are described. Nylon‐6 composites of 5–40 wt % filler loadings were compounded using an APV Baker twin‐screw extruder. Mica (25 wt %) brought about an increase in the Young's modulus, flexural strength, and flexural modulus but did not produce significant variations in tensile and impact strength. Hence different coupling agents were employed. It was observed that titanate coupling agent improved the tensile strength and the Young's modulus of the composites much while the impact properties were enhanced by the silane coupling agent. An attempt was made to use ?‐caprolactum in improving the interfacial adhesion of the filler and the matrix. It was observed that ?‐caprolactum improved the flexural modulus of the composites most. The effect of coupling agents on the dielectric strength, heat distortion temperature, and morphology were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4074–4081, 2006     

Effect of dendrimer‐like PAMAM grafted attapulgite on the microstructure and morphology of Nylon‐6

The effect of dendrimer‐like polyamidoamine grafted attapulgite (ATP‐PAMAM) on the microstructure and morphology of Nylon‐6 (PA6) was investigated. The ATP‐PAMAM nanoparticles were prepared by treating attapulgite (ATP) with heat and acid followed by grafting with polyamidoamine (PAMAM) molecules, which was confirmed by Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), and dispersion state in formic acid. The X‐ray diffraction (XRD) analysis result indicated that the grafting modification was occurred on the surface of fibrous crystals and did not shift the crystal structure of ATP. PA6/ATP‐PAMAM (G_2.0) nanocomposites with different modified ATP content were prepared by melt compounding in a twin screw extruder. XRD measurements suggested that the intensity of diffraction peak of α crystalline form of PA6 decreased gradually as the inclusion of ATP‐PAMAM(G_2.0) into the PA6 matrix, while that of γ crystalline form increased gradually. The results of molau experiment and scanning electron microscopy (SEM) observation showed not only a uniform dispersion of ATP‐PAMAM(G_2.0) in the PA6 matrix but also a strong interfacial adhesion between them. Mechanical investigation (by tensile test) showed an obvious improvement in the presence of surface modified ATP. POLYM. COMPOS., 35:627–635, 2014. © 2013 Society of Plastics Engineers     

SDS改性凹凸棒土的制备及其在PA6中的应用

以焦磷酸钠为分散剂,十二烷基磺酸钠(SDS)为改性剂,采用超声波与机械搅拌的方法对凹凸棒土(ATP)进行表面改性,制备出有机改性凹凸棒土(OATP),考察了不同pH值对改性效果的影响。利用FTIR、XRD、沉降试验、TEM等对改性前后的ATP进行表征。结果表明:SDS不能扩大ATP的层间距,只能以吸附的方式附着其表面,且pH为7时吸附效果最佳;OATP在有机介质中表现出很好的分散性。将OATP与聚酰胺6(PA6)经双螺杆挤出机熔融共混得到PA6/OATP复合材料,研究了OATP用量对该复合材料力学性能的影响;利用DSC分析了PA6/OATP复合材料热性能的变化。结果表明:当OATP用量为6份时,PA6的结晶度提高了18.2%,拉伸强度和弯曲强度分别较纯PA6提高了17.5%和13.9%。     

尼龙6/纳米钛合金复合材料的性能研究

将尼龙6和经有机化处理的纳米钛合金熔融共混制得复合材料,对该复合材料的力学性能、耐化学药品性和热性能进行了研究。结果表明,纳米钛合金可使复合材料的拉伸强度、拉伸屈服强度和拉伸弹性模量有所提高,但使复合材料的冲击强度和断裂伸长率降低;纳米钛合金可改善复合材料的耐化学药品性并使其分解残留量增加。     

Effects of PBO fiber and clay on the mechanical,morphological, and dynamic mechanical properties of NR/HDPE blends

Poly(p‐phenylene‐2,6‐benzobisoksazole) (PBO) and natural rubber (NR)/high density polyethylene (HDPE) composites were melt‐blended in a Haake internal mixer. The tensile strength, tensile modulus, and impact strength increased with fiber loading and optimized at 20%. Incorporation of clay into the NR/HDPE/PBO composites resulted in an improvement of tensile strength for NR/HDPE/PBO composites compared to the systems without clay. However, addition of clay was only effective at low contents (5–7.5%). Additional improvement of tensile strength, tensile modulus, and impact strength of the hybrid composite was observed on addition of liquid natural rubber (LNR). Scanning electron micrographs of the samples had indicated that the presence of clay decreased the domain size of the dispersed phase. Results on dynamic response showed that incorporation of clay and LNR into the composites had increased the storage modulus and reduced the tan δ. The shift of glass transition temperature (T_g) to higher values for composites also indicated good interaction between the fiber and the matrix. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.     

Development of basalt fiber‐reinforced thermoplastic composites and effect of PE‐g‐MA on composites

The thermoplastic matrix composites have gained great importance in last three decades. The chopped basalt fiber (mineral fiber) is considered to be a good fiber due to excellent properties as potential reinforcement of composite materials. In this work, composites of chopped basalt fiber (6 mm) with thermoplastic material Nylon‐6 (Polyamide‐6) were prepared and its mechanical and morphological properties were evaluated for automobile applications. The melt blending was carried out in corotating twin‐screw extruder and injection‐molded test samples were prepared for the analysis. The test samples of composite without coupling agent prepared by varying the loading of basalt fiber content of 5%, 10%, 15%, 20%, and 25% by weight and with coupling agent composite loading of Nylon‐6 and basalt fiber content were kept constant and the coupling agent (PE‐g‐MA) loading were changed as 1, 2, 3, 4, and 5 phr. The Mechanical and SEM properties were evaluated. From the test results, it was observed that the mechanical properties were improved with increasing coupling agent ratio. SEM images show good dispersion and adhesion of matrix and reinforcement. POLYM. COMPOS., 38:2798–2805, 2017. © 2015 Society of Plastics Engineers     

Short glass fiber reinforced ABS and ABS/PA6 composites: Processing and characterization

In this study acrylonitrile‐butadiene‐styrene (ABS) terpolymer was reinforced with 3‐aminopropyltrimethoxysilane (APS)‐treated short glass fibers (SGFs). The effects of SGF concentration and extrusion process conditions, such as the screw speed and barrel temperature profile, on the mechanical properties of the composites were examined. Increasing the SGF concentration in the ABS matrix from 10 wt% to 30 wt% resulted in improved tensile strength, tensile modulus and flexural modulus, but drastically lowered the strain‐at‐break and the impact strength. The average fiber length decreased when the concentration of glass fibers increased. The increase in screw speed decreased the average fiber length, and therefore the tensile strength, tensile modulus, flexural modulus, and impact strength were affected negatively and the strain‐at‐break was affected positively. The increase in extrusion temperature decreased the fiber length degradation, and therefore the tensile strength, tensile modulus, flexural modulus, and impact strength increased. At higher temperatures the ABS matrix degraded and the mechanical strength of the composites decreased. To obtain a strong interaction at the interface, polyamide‐6 (PA6) at varying concentrations was introduced into the ABS/30 wt% SGF composite. The incorporation and increasing amount of PA6 in the composites broadened the fiber length distribution (FLD) owing to the low melt viscosity of PA6. Tensile strength, tensile modulus, flexural modulus, and impact strength values increased with an increase in the PA6 content of the ABS/PA6/SGF systems due to the improved adhesion at the interface, which was confirmed by the ratio of tensile strength to flexural strength as an adhesion parameter. These results were also supported by scanning electron micrographs of the ABS/PA6/SGF composites, which exhibited an improved adhesion between the SGFs and the ABS/PA6 matrix. POLYM. COMPOS. 26:745–755, 2005. © 2005 Society of Plastics Engineers     

Studies on thermal,mechanical, morphological,and viscoelastic properties of polybenzimidazole fiber reinforced high density polyethylene composites

High density polyethylene (HDPE) and polybenzimidazole fiber (PBI) composites were prepared by melt blending in a twin screw extruder. The thermomechanical properties of PBI fiber reinforced HDPE composite samples (1%, 4%, and 8%) of fiber lengths 3 mm and 6 mm were investigated using differential scanning calorimeter (DSC), universal testing machine, rheometer, and scanning electron microscopy (SEM). The effects of fiber content and fiber lengths on the thermomechanical properties of the HDPE‐PBI composites were studied. The DSC analysis showed a decrease in crystallinity of HDPE‐PBI composites with an increase of fiber loading. SEM images revealed homogeneous distribution of the fibers in the polymer matrix. The thermal behavior of the composites was evaluated from thermogravimetric analysis and the thermal stability was found to increase with the addition of fibers. The evidence of homogeneous distribution was verified by the considerably high values of tensile strength and flexural strength. In the rheology study, the complex viscosities of HDPE‐PBI composites were higher than the HDPE matrix and increased with the increasing of PBI fiber loading. POLYM. COMPOS., 5–13, 2016. © 2014 Society of Plastics Engineers     

Influence of fiber treatment on the performance of sisal–polypropylene composites

This article concerns the effectiveness of MAPP as a coupling agent in sisal–polypropylene composites. The fiber loading, MAPP concentration, and fiber treatment time influenced the mechanical properties of the composites. It was observed that the composites prepared at 21 volume percent of fibers with 1% MAPP concentration exhibits optimum mechanical strength. SEM investigations confirmed that the increase in properties is caused by improved fiber‐matrix adhesion. The viscoelastic properties of the treated and untreated composites were also studied. From the storage modulus versus temperature plots, an increase in the magnitude of the peaks was observed with the addition of MAPP and fiber reinforcement, thus showing an improvement in stiffness of the treated composites. The damping properties of the composites, however, decreased with the addition of the fibers and MAPP. The thermal properties of the composites were analyzed through DSC and TGA measurements. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1336–1345, 2004     

回收聚丙烯/废书刊纸纤维复合材料结构与力学性能的研究

以废书刊纸纤维(OMGF)和回收聚丙烯(PP)为原料,马来酸酐接枝聚丙烯(MAPP)为相容剂,采用热压成型法制备了PP/OMGF木塑复合材料。研究了OMGF含量对复合材料拉伸性能及弯曲性能的影响,并采用红外光谱和扫描电子显微镜分析了OMGF的结构及复合材料的拉伸断面形貌。结果表明,OMGF对PP基体具有一定的增强作用,当OMGF含量为30%时,复合材料的拉伸强度和弯曲强度分别达到最大值29.53MPa和33.67MPa,比回收PP分别提高了51.6%和31.7%;随着OMGF含量的增加,复合材料的断裂伸长率逐渐下降,弯曲模量逐渐上升。扫描电子显微镜分析显示,当OMGF含量较低时,其与PP基体之间具有良好的界面相容性;当OMGF含量增加到50%时,界面相容性明显下降。     

Flame retardancy of hollow glass microsphere/rigid polyurethane foams in the presence of expandable graphite

Rigid polyurethane foams (RPUF) filled with various loadings of expandable graphite (EG) or/and hollow glass microspheres (HGM) were prepared by cast molding. The flame retardant properties of these composites were investigated by limiting oxygen index (LOI), horizontal and vertical burning tests. The composite with 10 wt % HGM and 20 wt % EG had the best flame retardant properties, and its LOI value reached 30 vol %. The addition of an appropriate loading of HGM improved the compressive strength and modulus of RPUF and EG/RPUF. When the HGM content arrived at 10 wt %, the compressive strength and modulus of the composites reached the maximum value. The dynamical mechanical analysis (DMA) showed that the addition of EG and HGM made the glass transition temperature shift to a higher temperature, and 10 wt % EG and 10 wt % HGM filled RPUF had the highest storage modulus. The scanning electronic microscope (SEM) observation indicates that the additives led to the decrease in the cell size. In addition, the flame retardant mechanism, the thermal properties, the burned surfaces and the interface surfaces were elucidated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation,morphology, and properties of silane‐modified MWCNT/epoxy composites

Both epoxy resin and acid‐modified multiwall carbon nanotube (MWCNT) were treated with 3‐isocyanatopropyltriethoxysilane (IPTES). Scanning electron microscopy (SEM) and transmission electronic microscope (TEM) images of the MWCNT/epoxy composites have been investigated. Tensile strength of cured silane‐modified MWCNT (1.0 wt %)/epoxy composites increased 41% comparing to the neat epoxy. Young's modulus of cured silane‐modified MWCNT (0.8 wt %)/epoxy composites increased 52%. Flexural strength of cured silane‐modified MWCNT (1.0 wt %)/epoxy composites increased 145% comparing to neat epoxy. Flexural modulus of cured silane‐modified MWCNT (0.8 wt %)/epoxy composites increased 31%. Surface and volume electrical resistance of MWCNT/epoxy composites were decreased with IPTES‐MWCNT content by 2 orders and 6 orders of magnitude, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Development of a transparent PMMA composite reinforced with nanofibers

Core‐shell composite nanofibers with PA‐6 (Nylon‐6) as core and Poly (methyl methacrylate) (PMMA) as shell were fabricated by a coaxial electrospinning method, which were later made into nanofiber reinforced transparent composites through a hot press treatment. Morphological and structural characterizations for the composite nanofibers and the transparent composites were realized in terms of SEM, TEM, and FTIR techniques. The fiber reinforcement feature of the PA‐6 was demonstrated by the SEM photos of a composite sample fractured in liquid nitrogen. Through TGA and DSC tests, it was observed that thermal endurance and glass‐transition temperature of the nanofiber reinforced composites altered in variation with the contents of the reinforcing PA‐6. Experimental results indicated that the mechanical performance of the nanofiber reinforced transparent composites was obviously improved, and its transparency decreased a little with an increase in the PA‐6 content. As long as, however, a sacrifice of 10% in transparency was specified, an increment of more than 20% in the mechanical properties of the composites was achievable. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

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.