High performance of bamboo‐based fiber composites from long bamboo fiber bundles and phenolic resins

Lignocellulosic materials can be used for the development of bio‐based composites. This study explores the potential of long bamboo fiber bundles extracted directly from bamboo stems using the novel mechanical method and bamboo‐based fiber composites (BFC) fabricated using long bamboo fiber bundles and phenolic resins via cold pressing and thermal cure process. The microstructure, mechanical properties, and durability of BFC were evaluated, results being compared with raw bamboo and other commercialized bamboo fiber composites. The mechanical properties of BFC reinforced with 87% (w/w) long bamboo fiber bundles increased more than 50% than those of raw bamboo and were significantly higher than those of other bamboo‐based composites. Lower water absorption and thickness swelling were obtained in the case where bamboo fiber bundles with the small fineness. Higher tensile strength was obtained in the case where bamboo fiber bundles with large sizes of bamboo fiber bundles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40371.     

Evaluation of polymerization shrinkage in dental restorative experimental composites based: BisGMA/TEGDMA,filled with MMT

This work concerns to the investigation of the polymerization shrinkage and mechanical properties in dental restoratives experimental composites filled with nano clay Montmorilonite (MMT) Cloisite^® 10A nanoparticles, in glycidyl methacrylate resin, using experimental composites filled with silanized Aerosil OX‐50 Silica as a control group. Six formulations with BisGMA/TEGDMA based polymeric matrix (three added with MMT and three added with silanized silica as filler) containing 50, 60, and 70 wt % were investigated. Characterization of the experimental composites was established with the following analyses: Scanning Electron Microscope, (SEM); Thermo‐Mechanical Analysis, (TMA) for Shrinkage Polymerization; Differential Scanning Calorimetry Analysis (DSC); Knoop Micro Hardness analysis; X‐ray Diffraction (XRD); Degree of Conversion (DC); Elastic Modulus and Flexural Strength; Transmission Electron Microscopy (TEM). Statistical Analyses were realized using two‐way ANOVA (type and amount of filler) and Tukey's test. TMA results showed that composites filled with MMT nanoparticle present statistically lower polymerization shrinkage values and statistically high degree of conversion in all formulations tested, when compared to composites filled with silanized silica. XRD and TEM analyses showed evidences of the intercalation phenomenon in the MMT nanoparticles in relation to BisGMA/TEGDMA polymeric matrix. However, for Flexural Strength, groups filled with MMT nanoparticle showed statistically lower values in all concentration tested. At high filler concentration it was observed the appearance of tactoids and functionalization of MMT nanoparticle did not promote a strong interface adhesion between polymeric matrix and filler. In order to adjust the mechanical properties, it would be convenient to promote the concentration optimization of MMT nanoparticles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43543.     

Monitoring of nylon 6,6/carbon fiber composites processing by X‐ray diffraction and thermal analysis

This work reports a study made to obtain carbon fiber/nylon 6,6 prepreg composites by hot‐compression molding. Thermogravimetric analysis (TG) and crystallinity degree determination were carried out to monitor the nylon 6,6 behavior during the different steps of the composite processing. The homogeneity of the carbon fiber/polymer matrix distribution was verified using microscopic analyses and the fiber content was determined by the acid‐digestion method. The results show that the processing parameters employed were adequate, allowing the manufacture of laminates with good texture and an adequate reinforcement/matrix relation (60/40). However, improvements need be done to minimize the pullout effect observed in the tensile specimens. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3114–3119, 2002     

Effect of processing conditions on wood and glass fiber length attrition during twin screw composite compounding

In this study, we compare the effect of twin-screw extrusion processing on the attrition of wood fibers (WFs) with glass fiber. The effects of process variables and screw design on fiber length were investigated by performing a range of dead-stop experiments where the extruder was stopped, opened-up, and compound removed from the screw elements. Fibers, chemically extracted from the polypropylene matrix, were analyzed for length and width using a commercial fiber analyzer. It was found that WF length attrition and composite properties were less affected by screw design and twin-screw processing conditions (feed rate and screw speed) than glass fiber. Length weighted fiber length and X50 length (a measure used in particle size analysis) were equally correlated with process conditions and composite performance for both fiber types. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48551.     

Effects of extrusion process,type and content of clays,and foaming process on the clay exfoliation in HMS PP composites

The use of a high melt strength polypropylene (HMS PP) matrix reinforced with layered clays could be very useful to improve the properties of materials produced with processes involving melt stretching, like foaming. The control of the particles structure, that is, the degree of exfoliation and the clay distribution in the polymeric matrix, is the key to achieve the desired properties. In this study, the effects of the extrusion process, the clay type and content, and the foaming process on the morphology of different HMS PP based composites are studied. Both, natural and organomodified clays were used. The extrusion process has a negative effect in the composites containing natural clays as their interlayer distance decreases as the number of extrusion cycles increases. On the contrary, this process improves the intercalation of the organomodified clays. However, in both composites the interlayer spacing decreases when the clay content increases. While a percolated network is formed in the composites containing organomodified clays, no network is formed with the natural clays. Finally, the effect of the foaming process has also been analyzed. The Improved Compression Moulding (ICM) route was used to produce the foamed materials. This technique subjects the materials only to a temperature and a pressure gradient without applying any other external forces that could contribute to the clay exfoliation. In this way, only the effects of foaming and melt stretching are observed. In both composites, an increase in the interlayer distance is observed when the materials are foamed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42828.     

Fabrication of novel polyaniline/flowerlike copper monosulfide composites with enhanced electromagnetic interference shielding effectiveness

Novel polyaniline (PANI)/flowerlike CuS composites with improved electromagnetic interference (EMI) shielding effectiveness (SE) were prepared through the in situ polymerization of PANI into the flowerlike CuS microspheres. X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible optical absorption spectroscopy, thermogravimetric analysis, electrical conductivity testing, and EMI SE testing were used to characterize the as‐obtained products. The results reveal that the flowerlike CuS was uniformly coated by a PANI shell. Most importantly, compared with the original CuS and pure PANI, the novel PANI/flowerlike CuS composites exhibited a remarkably enhanced SE. With a thickness of 3 mm, the optimal EMI SE of the PANI–CuS composites reached ?45.2 dB at 2.78 GHz, and an improved shielding efficiency below ?18 dB was also obtained over the frequency range from 300 kHz to 3 GHz. This suggested that these novel PANI/flowerlike CuS composites have promising applications in the field of shielding materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45232.     

Polypropylene–wood fiber composites: Effect of treatment and mixing conditions on mechanical properties

Polypropylene/wood fiber composites were prepared at three different temperatures: 170°C, 180°C, and 190°C. The surface of wood fibers was modified through the use of silane coupling agents and/or coating with polypropylene or maleated polypropylene. The fiber coating was performed by propylene polymerization in the presence of wood fibers or by immersion in an o-dichlorobenzene polypropylene (or maleated polypropylene) solution. Tensile and three-point bending tests were performed in order to evaluate the adhesion between matrix and wood fibers. Evidence shows that 180°C is the best mixing temperature, while the use of vinyl-tris (2-methoxy ethoxy) silane with or without maleated polypropylene coating is the best surface treatment. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1227–1235, 1997     

Effect of the drawing process on the wet spinning of polyacrylonitrile fibers in a system of dimethyl sulfoxide and water

The effect of the drawing process on the structural characteristics and mechanical properties of polyacrylonitrile (PAN) fibers was comparatively studied. The protofibers extruded from the spinneret were the initial phase of stretching, which involved the deformation of the primitive fiber with the concurrent orientation of the fibrils. Wet‐spun PAN fibers observed by scanning electron microscopy exhibited different cross‐sectional shapes as the draw ratio was varied. X‐ray diffraction results revealed that the crystalline orientation of PAN fibers increased with increasing draw ratio; these differences in the orientation behaviors were attributed to the various drawing mechanisms involved. The crystalline and amorphous orientations of the PAN fibers showed different features; at the same time, the tensile properties were strongly dependent on the draw ratio. However, the stream stretch ratio had most influence on the tensile strength and the orientation of PAN fibers for the selected process parameters. Electron spin resonance proved that the local morphology and segmental dynamics of the protofibers were due to a more heterogeneous environment caused by the sequence structure. Differential scanning calorimetry indicated that the size and shape of the exotherm and exoenergic reaction were strongly dependent on the morphology and physical changes occurring during fiber formation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1026–1037, 2007     

Deinked and acetylated fiber of newspapers

Recently, the incorporation of lignocellulosic materials as reinforcing agents or as fillers in polymer composites has received an increased attention. Although natural fibers have a number of advantages over glass fibers, the strong polar character of their surface is a limiting factor, as compatibility with strongly apolar thermoplastic matrices is very low. Such problems of incompatibility may be overcome with fiber pretreatments, which can enhance compatibility, albeit having a negative impact on the economics. In this study, the newspaper is deinked and acetylated. The effect of esterification between the acetyl groups and the hydroxyl groups of the fiber was examined by Fourier transform infrared. X‐ray diffraction and scanning electron microscopy were used to characterize the crystallinity and the surface morphology of the untreated deinked and acetylated fibers (newspaper). The thermal stability of deinked and acetylated fibers was slightly decreased. It was also shown that the deinking increased the crystallinity of newspaper fibers while acetylating decreased this crystallinity. Cellulose acetate is one of the most important cellulose derivatives and its main applications are its use in composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Peak‐fitting analysis of cotton fiber powder X‐ray diffraction spectra

The precision and accuracy of diffraction peak positions resolved from the powder X‐ray diffraction spectra of cotton fibers by means of the residuals peak‐fitting procedure of a commercial peak‐fitting software package (PeakFit®) was investigated to explore the potential of such programs in providing reliable data that are not readily apparent in diffuse X‐ray spectra. Each intensity spectrum was fitted by employing a Gaussian function as the peak profile. The precision of 15 pairs of the resolved diffraction peaks is 0.0017 mm; 9 of the 15 pairs fall into the 99% confidence interval. The precision in 2θ of four commonly identified peaks through four independent fittings is from 0.002 to 0.014°. The 2θ accuracy of the resolved peaks is good in comparison to data calculated for both the traditionally accepted and the more recently revised concepts of the cellulose I crystal structure. A peak resolved at about 15.3° may be attributed to the triclinic crystal structure component of cellulose I. Although distinct peaks are not readily apparent in the diffuse spectrum of cellulose, peak‐fitting procedures may provide additional data for structure determination. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2019–2024, 2004     

Positive temperature coefficient effect and interaction based on low‐density polyethylene/graphite powder composites

In this article, the positive temperature coefficient (PTC) and interaction based on low‐density polyethylene (LDPE) filled with the loading of graphite (G) powder have been investigated. The dependence of the room temperature resistivity on filler content showed the significant decrease. The PTC behavior enhanced with increasing graphite content but this was not always the case. The maximum PTC effect was observed in LDPE/G composites (G, 45 wt %) with the relatively low room temperature resistivity. The thermal behavior was measured by differential scanning calorimetry (DSC). The structure characteristic for LDPE/G composites was examined by X‐ray diffraction (XRD), field‐emission scanning electron microscopy (SEM), and stress–strain test. The fact was revealed that the slight interaction between LDPE matrix and graphite may lead to change the thermal‐electric properties of the PTC materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Study on the properties of polyethylene/montmorillonite nanocomposites prepared by a novel vane mixer

A novel mixer‐vane mixer which is based on elongation flow was used to prepare high‐density polyethylene (HDPE)/montmorillonite (MMT) nanocomposites without any additives. The effect of elongation flow on MMT intercalating in HDPE matrix was studied in terms of rotor speed and mixing time. X‐ray diffraction and transmission electron microscope analyses showed that exfoliated and intercalated nanostructures were obtained when the rotor speed was 40 and 50 rpm, and mixing time was 6 minutes. For all samples prepared by vane mixer, MMT layers showed fine intercalation in the nanocomposites. Differential scanning calorimetry and thermogravimetric analysis were used to study the thermal properties of the nanocomposites. The results showed that the addition of MMT can improve the crystallization of the HDPE. Tensile test revealed the relationships between the mechanical properties and process parameters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42600.     

Additive manufacturing of high-strength polyamide 6 composites reinforced with continuous carbon fiber prepreg

The additive manufacturing of continuous fiber reinforced thermoplastics (CFRTPs) paves way for the high-strength, light-weight components for variety of load-bearing applications. In this work, the continuous carbon fiber reinforced PA6 (CCF-PA6) composites was successfully printed from the prepreg filament. The prepreg filament was prepared in-house by impregnating the heat-and-acid treated 1 K carbon fiber bundle with the molten PA6. The tensile strength of the prepreg filament, which contained with 40 vol% CF, reached 984 MPa. The unidirectional CCF-PA6 specimens were subsequently 3D-printed with the prepreg filament, and the mechanical strength of those 3D-printed specimens were tunable by adjusting a set of printing parameters, such as layer thickness, hatch spacing and printing temperatures. The highest tensile strength of the specimen reached 555 MPa. Those specimens also exhibited outstanding mechanical strength at elevated temperatures, still reaching 184 MPa at 150°C. The mechanical strength of those specimens was dependent on the content of the fiber. This study can hopefully provide new insights for feedstock design and spur novel ideas in tailoring the mechanical properties of the 3D-printed CFRTPs.     

Thermal conductivity and electromagnetic shielding effectiveness of composites based on Ag‐plating carbon fiber and epoxy

Thermally conductive and electromagnetic interference shielding composites comprising low content of Ag‐plating carbon fiber (APCF) were fabricated as electronic packing materials. APCF as conductive filler consisting of carbon fiber (CF) employed as the structural component to reinforce the mechanical strength, and Ag enhancing electrical conductivity, was prepared by advanced electroless Ag‐plating processing on CF surfaces. Ag coating had a thickness of 450 nm without oxide phase detected. The incorporation of 4.5 wt % APCF into epoxy (EP) substrate yielded thermal conductivity of 2.33 W/m·K, which is approximately 2.6 times higher than CF–EP composite at the same loading. The APCF–EP composite performed electromagnetic shielding effectiveness of 38–35 dB at frequency ranging from 8.2 to 12.4 GHz in the X band, and electromagnetic reflection was the dominant shielding mechanism. At loading content of APCF up to 7 wt %, thermal conductivity of APCF–EP composites increased to 2.49 W/m·K. Volume resistivity and surface resistivity decreased to 9.5 × 10³ Ω·cm and 6.2 × 10² Ω, respectively, which approached a metal. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42306.     

Influence of wood fiber size on extrusion foaming of wood fiber/HDPE composites

Foaming of wood fiber/plastic composites (WPC) with a fine‐celled structure can offer benefits such as improved ductility and impact strength, lowered material cost, and lowered weight, which can enhance their utility in many applications. Although a great deal of attention is now being focused on these composites in the scientific literature, there are still numerous aspects of WPC processing that need elucidation. In this context, this article investigates the effects of wood fiber (WF) size on fine‐celled extrusion foaming of WPC in terms of cell size, cell size distribution, and foam density. The effects of WF size and coupling agent content on the viscosity of WPC are also investigated. The experimental results revealed that the small‐sized WF provides a better cell morphology, a smaller cell size, and a better cell uniformity in WPC foams. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Enhanced dielectric properties of poly(vinylidene fluoride)–surface functionalized BiFeO3 composites using sodium dodecyl sulfate as a modulating agent for device applications

In this work, we prepared a series of poly(vinylidene fluoride) (PVDF)–surface functionalized BiFeO₃ (h‐BFO)–Sodium dodecyl sulfate (SDS) composite films by solvent casting method to investigate the effect of SDS in the composites. The X‐ray diffraction confirmed that the structure of h‐BFO significantly changed in the PVDF‐(h‐BFO)‐SDS composite in comparison with the rhombohedral structure of pure BiFeO₃. The microscopic study illustrated that the composite with a higher percentage of SDS content facilitated the dispersion as well as proper distribution of ceramic particles in the polymer matrix. The presence of different functionalities of respective polymer and the modified fillers was confirmed by FTIR Spectrophotometer. The dielectric and electrical study done by Impedance Analyzer revealed that the SDS treated surface functionalized composites showed relatively higher dielectric properties than that of two phase composites and pure polymer. Finally, the ferroelectric properties of the composite films done by P‐E loop tracer revealed that the SDS‐treated composites showed an enhanced remanent polarization. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45040.     

Short fiber spraying process of all-oxide ceramic matrix composites: A parameter study

Fiber spraying processes have been established for polymer matrix composites for decades. In this study, we transferred an automated fiber spraying process to short fiber bundle-reinforced Nextel 610/ Al₂O₃-ZrO₂ oxide fiber composites (SF-OFC). The effect of the processing factors travel height, spray angle, and movement speed on the specimen strength was analyzed in a full factorial experimental design. As a result, the significance of the travel height as well as the interaction between travel height and movement speed was demonstrated. Furthermore, the influence of the fiber length (14, 28, 56, and 112 mm) on the bending stress and strain was investigated. Independent of the used fiber length, the SF-OFC exhibited an excellent quasi-ductile fracture behavior with bending strains in the range of .6% and in-plane isotropic material properties. The average bending strength increased from 133 ± 27 MPa with 14 mm fiber reinforcements to 163 ± 29 MPa with 112 mm fibers. The achieved bending strengths clearly exceeded the off-axis properties of currently used fabric-reinforced OFC. These properties, combined with the excellent drapability and cost effectiveness, make the novel material highly promising for industrial applications such as flame tubes, burner nozzles, kiln furnitures, or foundry components.     

Flexible X‐ray radiation protection membrane PVA/pb(NO3)2 microcapsule composites supported by bacterial cellulose

Flexible and nonpoisonous X‐ray‐shielding membranes supported by bacterial cellulose (BC) were prepared, in which X‐ray‐shielding materials were of microcapsule structure by using polyvinyl alcohol as shell and lead salt as core. The effect of the wall/core interaction and the amount of cross‐linking agent were taken into consideration to find the optimal reaction conditions. The morphology, microcapsule size, and lead salt release properties were investigated. After supported by BC, the flexible and potable membranes for X‐ray radiation protection were prepared and the shielding properties were evaluated, which indicated a good X‐ray‐shielding material. We set up a new method to prepare flexible and portable X‐ray radiation protection membranes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43120.     

碳纤维在电磁屏蔽材料中的应用研究

本文简要介绍了电磁屏蔽的原理和碳纤维的性能，分析、论述了碳纤维在聚合物基电磁屏蔽材料中应用研究的主要形式．     

Impact of processing conditions and sizing on the thermomechanical and morphological properties of polypropylene/carbon fiber composites fabricated by material extrusion additive manufacturing

For the 3D printed composites, fiber alignment is affected by the direction of melt-flow during extrusion of filaments and subsequently through the printing nozzle. The resulting fibers orientation and the fiber-matrix compatibility have a direct correlation with mechanical properties. This study investigates the impact of processing conditions on the state of the carbon fiber types and their orientation on the mechanical properties of 3D-printed composites. Short and long carbon fibers were used as starting reinforcing materials, and the state of fibers at the beginning and on the printed parts were evaluated. Strong anisotropy in terms of mechanical properties (flexural and impact properties) was observed for the samples printed with different printing orientations. Interestingly, the number of voids in the printed composites was found to be correlated with the fiber types. The present work provides a step towards the optimization of tailored composite properties by additive manufacturing.