Preparation and Properties of Biodegradable Spent Tea Leaf Powder/Poly(Propylene Carbonate) Composite Films

The aim of the present work is to develop novel bio-based lightweight material with improved tensile and thermal properties. Spent tea leaf powder (STLP) was used as a filler to improve the tensile and thermal properties of polypropylene carbonate (PPC). Tea is an important material used in hotels and households, and spent tea leaf is a resulting solid waste. Composite films with STLP were obtained by the solution casting method. These films were characterized by optical and scanning electron microscopy, Fourier transform-infrared spectroscopy, thermogravimetric analysis, and tensile testing to examine the effect of filler content on the properties of the composites. The results showed that composite films have increased tensile strength due to enhanced interfacial adhesion between the filler and the matrix. In addition, the composite films also exhibited higher thermal degradation temperatures than pure polypropylene carbonate. The morphology results indicate that there is a good interface interaction between STLP and PPC. Results of the study reveal STLP to be a promising green filler for polymer plastics.     

Surface treatment of lignocellulose biofiller for fabrication of sustainable polylactic acid biocomposite with high crystallinity and improved burning antidripping performance

In this work, we incorporated surface-treated coffee husks (CHs) into a polylactic acid matrix to fabricate environmentally friendly composites, with high crystallinity and satisfactory antidripping performance for flame retardancy. CHs are lignocelluloses that contain cellulose, hemicellulose, and lignin that are present as interlinked complex macromolecular structure. CH spectroscopic characterization confirmed that the phytic acid/amine silane agent was successfully attached and bonded with the cellulose portion of CHs. Morphological analysis of the composites revealed that the surface-treated CHs helped to improve the interfacial interaction between the filler and the matrix. Furthermore, the differential scanning calorimetry analysis showed that the crystallinity of the composites increased with CH loading. Flammability and combustion tests confirmed that the combined effect of P/Si/N on surface treatment improved the flame retardance behavior of the composites. The tensile strength and modulus of the composites exhibited a 28.7% and 34.4% increase compared with the corresponding composite with raw CHs.     

Polymer matrix influence on stability of wood polymer composites

The aim of the presented work is to show the influence of the various polymer matrices and the different amounts of the cellulose filler on the composites properties. Samples based on polypropylene, polystyrene, polyoxymethylene, acrylonitrile butadiene styrene, polyester resin, and polylactic acid with different contents of cellulose fibers were prepared by injection molding process. The mechanical and dielectric properties of these composites were studied in order to check whether investigated wood polymer composites fulfill requirements for their application in electrical devices. For all tested composites, a linear increase of modulus with cellulose content was observed. Addition of cellulose to the tested polymers significantly reduces strain at break. In the case of polypropylene and polyoxymethylene composites, the tensile strength increases with the content of the filler. For other materials, there is an inverse relationship, namely the addition of cellulose decreases the tensile strength. The electrical strength decrease was observed with increased cellulose content for the majority of the investigated composites. Polar groups incorporated by cellulose fibers have led to dielectric constant increase. Furthermore, aging of composites in mineral oil and evaluation of water uptake for wood–plastic samples were performed. Wood polymer composites have changed significantly after aging. The water diffusion coefficients were determined, and the significant influence of the amount of cellulose on the water absorption was shown. Copyright © 2015 John Wiley & Sons, Ltd.     

A review on flammability of epoxy polymer,cellulosic and non‐cellulosic fiber reinforced epoxy composites

Natural fiber is well‐known reinforcement filler in polymer‐matrix composites. Composite components like organic polymers and natural fibers are natural fire conductors as the natural fiber consists of cellulose, hemicellulose, and lignin, and hence are as highly flammable as wood. Natural fiber reinforced composite materials are progressively being used in a variety of applications where their fire response is a hazardous consideration, for example, in the automotive (transportation) and building‐construction industries. As a result, an awareness of their performance or response during a fire and the use of conventional fire retardants are of great importance, as they are subject to thermal decomposition when exposed to intensive high heat or fire sources. In this review paper, fire flammability is the main concern for cellulosic and non‐cellulosic fiber‐reinforced polymer composites, especially epoxy composites. This paper reviews the literature on the recent developments in flammability studies concerning polymers, epoxy polymers, cellulosic‐fibers, and non‐cellulosic fiber‐reinforced epoxy bio‐composites. The prime objective of this review is to expand the reach of “fire retardants for polymer materials and composites” to the science community, including physicists, chemists, and engineers in order to broaden the range of their applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermal Analysis of Micro- and Nano-Lignocellulosic Reinforced Styrene Maleic Anhydride Composite Foams

The aim of this study was to measure the thermal properties of foamed nano/macro filler–reinforced styrene maleic anhydride (SMA) composites. SMA (66%) as a polymer matrix (10% maleic anhydride content) and various fillers including wood flour, starch, α-cellulose, microcrystalline cellulose and cellulose nanofibrils as reinforcing agents (30%) and lubricant (4%) were used to manufacture the composites in a twin-screw extruder. According to the thermogravimetric analysis (TGA) results, thermal degradation of all the foamed composites was found to be lower than that of SMA composites. The storage modulus values were negatively affected with a second time foaming (reprocessing [recycling] the initially processed composites a second time), as were loss modulus and T_g. As a result, second-time-foamed composite modulus values were lower than those of the foamed composites. According to the melt flow index (MFI) results, viscosity of the SMA was found to increase with the addition of fillers.     

Determination of filler content for natural filler polymer composite by thermogravimetric analysis

Determination of filler content by thermogravimetric (TG) analysis is commonly utilized to investigate the effectiveness of processing methods for composite materials and to quantify the dispersion of filler within the matrix. However, the existing analysis method is not capable of accurately predicting the filler content for natural fiber composites for the case where thermal degradation of the filler and matrix occurs within similar temperature ranges. In the present study, the authors have proposed a generic equation for the determination of filler content which can be utilized for any given range of thermal degradation temperatures in natural filler polymer composites. Oil palm shell unsaturated polyester composites were selected to verify the proposed equation using the TG test with the results indicating good agreement between the estimated and experimental filler contents with a maximum error on the order of 10 %. The suggested technique provides a simple, yet generic, approach to determining the filler content of green or lignocellulose-based polymer composites by TG analysis.

     

Improving breakdown strength and energy storage efficiency of poly(vinylidene fluoride-co-chlorotrifluoroethylene) and polyurea blend films by double layer structure design

All-organic composites are widely used in energy storage application due to the high breakdown strength performance, but the improvement of energy storage was limited by the relatively low dielectric constant. Therefore, to satisfy the high demands of dielectric materials, energy storage properties of polymer composites should be further enhanced. In this article, poly(vinylidene fluoride-co-chlorotrifluoroethylene) (P(VDF-CTFE)) and polyurea (PUA), which are known as high dielectric ferroelectric material and linearly high energy storage efficiency material respectively, are composited through double layer (DL) casting method for the first time. The properties of DL structured composite film is contrasted with solution blending structure especially in energy storage efficiency, and the results demonstrate that DL structure design can make great use of advantages of two materials and also can avoid the influence of phase separation between P(VDF-CTFE) and PUA efficiently. Moreover, high breakdown strength (6180 kV/cm) and high energy storage efficiency (77%) of DL composites can be realized simultaneously by incorporating PUA as an insulating layer, and the mechanism is discussed in detail. This work provides an effective route to improve the energy storage properties of polymer dielectric materials and shows great application potential.     

The Effect of 3-aminopropyltrimethyoxysilane (AMEO) as a Coupling Agent on Curing and Mechanical Properties of Natural Rubber/Palm Kernel Shell Powder Composites

This research is conducted using palm kernel shell powder (PKS) as filler in natural rubber The effect of 3-aminopropyltrimethoxysilane as coupling agent on composites were studied at different palm kernel shell loading i.e, 0 5, 10, 15 and 20 phr The palm kernel shell was crushed and sieved to an average particle size of 5.53 μm The palm kernel shell filled natural rubber composites were prepared using laboratory size two roll mill The curing characteristics such as scorch time, cure time and maximum torque were obtained from rheometer The palm kernel shell powder filled natural rubber composites were cured at 150^oC using hot press according to their cure time Curing characteristics, tensile properties, rubber-filler interaction and morphological properties of palm kernel shell powder filled natural rubber were studied Scorch time and cure time show reduction but tensile strength, elongation at break, modulus at 100% (M100) and modulus at 300% (M300) increased with the presence of 3-aminopropyltrimethyloxysilane Rubber-filler interaction studies showed that rubber filler interaction in natural rubber filled with palm kernel shell powder improved with incorporation of 3-aminopropyltrimethyoxysilane.     

IFSS, TG, FT-IR spectra of impregnated sugar palm (Arenga pinnata) fibres and mechanical properties of their composites

This study aimed to investigate the effect of resin impregnation on the interfacial shear strength (IFSS), thermogravimetric (TG) and fourier transform infrared (FT-IR) of sugar palm (Arenga pinnata) fibres. In addition, the effect of resin impregnation on the mechanical properties of sugar palm fibre reinforced unsaturated polyester (UP) composites was also studied. The fibres were impregnated with UP via vacuum resin impregnation process at a pressure of 600 mmHg for 5 min. Composites of 10, 20, 30, 40 and 50 % fibre loadings were fabricated and tested for tensile and flexural properties. It was observed that the impregnation process caused the fibres to be enclosed by UP resin and this gave a strong influence to the increase of its interfacial bonding by the increase of its IFSS from single fibre pull-out test. It was also observed with TG and FT-IR spectra that the impregnated fibre had lower moisture uptake than the control and there was no significant increase in thermal stability of the impregnated fibre. The sequence of fibre decomposition started from the evaporation of moisture, hemicelluloses, cellulose, lignin and finally ash content and the presence of these components were proven by FT-IR spectra. For the composite specimens, due to the high interfacial bonding of the impregnated fibre and the matrix, the impregnated composites showed consistently higher tensile strength, tensile modulus, elongation at break, flexural strength, flexural modulus and toughness than the control samples. It was also observed that 30 % fibre loading gave optimum properties.     

Tensile,thermal, and antibacterial characterization of composites of cellulose/modified Pennisetum purpureum natural fibers with in situ generated copper nanoparticles

Eco-friendly all cellulose composites were developed using cellulose as matrix and nanocomposite (in situ generated copper nanoparticles modified Napier Grass Fibers (NGFs)) as fillers for the antibacterial applications. The content of the nanocomposite filler was increased from 1?wt.% to 5?wt.% in the cellulose matrix. All these composites were characterized by Scanning Electron Microscopy (SEM), Tensile, Thermo Gravimetric Analysis (TGA), and antibacterial tests. SEM-EDX analysis revealed the in situ generation of copper nanoparticles on the surface of the films. Further, all cellulose composites showed good thermal stability. A minimum of 30% increase in char residue was observed in all cellulose nanocomposites compared to matrix. Antibacterial analysis indicated an excellent clear zone formation against both Gram Negative (Escherichia coli) and Gram Positive (Staphylococcus) bacteria. Hence, all these cellulose nanocomposite films can be considered as antibacterial packaging and dressing materials in medical field.     

The effect of shear on mechanical properties and orientation of HDPE/mica composites obtained via dynamic packing injection molding (DPIM)

The interfacial interaction and orientation of filler play important roles in the enhancement of mechanical performances for polymer/inorganic filler composites. Shear has been found to be a very effective way for the enhancement of interfacial interaction and orientation. In this work, we will report our recent efforts on exploring the development of microstructure of high density polyethylene (HDPE)/mica composites in the injection‐molded bars obtained by so‐called dynamic packing injection molding (DPIM), which imposed oscillatory shear on the melt during the solidification stage. The mechanical properties were evaluated by tensile testing and dynamic mechanical analysis (DMA), and the crystal morphology, orientation, and the dispersion of mica were characterized by scanning electron microscopy and two‐dimensional wide‐angle X‐ray scattering. Compared with conventional injection molding, DPIM caused an obvious increase in orientation for both HDPE and mica. More importantly, better dispersion and epitaxial crystallization of HDPE was observed on the edge of the mica in the injection‐molded bar. As a result, increased tensile strength and modulus were obtained, accompanied with a decrease of elongation at break. The obtained data were treated by Halpin–Tsai model, and it turned out that this model could be also used to predict the stiffness of oriented polymer/filler composites. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation and Properties of Cellulose/Waste Leather Buff Biocomposites

The aim of the present work was to utilize waste leather buff (WLB) as filler in cellulose and make biocomposites for packaging applications such as wrappers. Cellulose was dissolved in the environmentally friendly ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl). To this solution, WLB was added in amounts of 5 to 25 wt.% of cellulose. The cellulose and cellulose/WLB composite films were prepared by regenerating the corresponding cast solutions in a water coagulation bath followed by washing and drying. These films were tested for their tensile properties, thermal stability, and morphology. The tensile modulus and strength of the composite films were lower than those of the matrix. The lowering of the tensile modulus and strength with increasing WLB loading was attributed to the random orientation of the leather fibers of WLB in the composites. However, the % elongation at break of the composite films was found to be higher than that of the matrix and increased with increasing WLB content. The possible interaction between the matrix and WLB filler was probed using FT-IR analysis. The thermal stability of the composite films was higher than that of the matrix. The increase in thermal stability of the composite films was attributed to cross-linked collagen protein leather fibers in WLB. The fractographs of the composite films indicated good interfacial bonding between cellulose and leather fibers of WLB. These composite films may be considered for packaging and wrapping applications.     

Rheological properties of wood polymer composites at high shear rates

This paper presents the rheological properties of wood-polymer composites (WPC) with a polypropylene (PP) matrix in the corrected shear rate range from approx. 20 s⁻¹ to 150 000 s⁻¹. Tests were conducted using a capillary rheometer and a rheological head of the author's construction, for which the working element is a thermoplastic injection moulding machine. The constructed tool was found to be very useful, especially for the determination of the processing characteristics of WPC composites containing a large particle-size filler. It was observed that the rheological properties of wood-polymer composites in the shear rate range of up to several thousand s⁻¹ significantly depended on the filler content of the polymer matrix; at the same time, at higher shear rate, a clear decrease in the effect of the wood filler content on the viscosity of the composites and on the flow behaviour, as described by the power law, took place.     

Influence of pineapple leaf fiber and it's surface treatment on molecular orientation in,and mechanical properties of,injection molded nylon composites

The objective of his work is to show that pineapple leaf fiber (PALF) can be used successfully to reinforce a high melting polymer such as nylon. One of the most important barriers to the utilization of lignocellulosic materials in polymer matrix composites is their limited temperature resistance. As a consequence, they are mostly used to reinforce low melting temperature polymers such as polyethylene and polypropylene as well as polystyrene. However, this work reveals that PALF can be used to reinforce nylon. This is because of its very low lignin content. Nylon 6/66 composites containing a fixed amount of 20 wt % PALF in the form of short and fine fibers were prepared with a laboratory twin screw extruder and then injection molded. The mechanical properties of three types of PALF, i.e. untreated, alkaline- and silane-treated, were studied. Significant improvements in modulus and heat distortion temperature were obtained. The crystalline structure and orientation in the injected composites were investigated with synchrotron wide angle x-ray scattering (WAXS). It was found that both PALF and nylon crystallites oriented well along the flow direction and this is the key factor for the improvements observed.     

Thermogravimetry on wood powder-filled polyurethane composites derived from lignin

Novel polyurethane (PU) composites whose matrix is derived from lignin, molasses polyol and filler from wood powder were successfully prepared. Two kinds of polyol were mixed 0/100 to 100/0 in seven steps, and filler content was varied from 50 to 100 mass % to polyol content. Decomposition behaviour of PU composites was investigated by thermogravimetry. Apparent density and mechanical properties of the above composites were also measured. Surface texture was observed by scanning electron microscopy. Thermal decomposition of PU composites was found to occur in two stages. The first decomposition observed at 570–580 K (DT _d1, peak temperature of derivative curve) is attributed to the matrix of composites. The second stage decomposition depending on filler content, observed in a temperature range from 590 to 630 K (DT _d2), is attributable to filler homogenously associated with PU matrix. Marked differences were not found, when the kinds of lignin and molasses polyol composition were varied. The above PU composites were found to be thermally stabilised by the introduction of filler.     

Poly‐(ε‐caprolactone) (PCL) and poly(hydroxy‐butyrate) (PHB) blends containing seaweed fibers: Morphology and thermal‐mechanical properties

Massive quantities of marine seaweed, Ulva armoricana are washed onto shores of many European countries and accumulates as waste. Attempts were made to utilize this renewable resource in hybrid composites by blending the algal biomass with biodegradable polymers such as poly(hydroxy‐butyrate) and poly‐(ε‐caprolactone). Compression‐molded films were developed and examined for their morphological, thermal and mechanical property. The Ulva fibers were well dispersed throughout the continous matrix exhibiting considerable cohesion with both polymers. Occasionally, regions with exposed fibres or aggregates were visible. About 50% algal content seemed to be an ideal concentration, thereafter, thermal stability was impacted. A progressive decrease in melting heat (ΔH_m) was observed with increased algal content as well as a decrease in the crystallinity of the polymer matrix due to the presence of the organic filler. The addition of algal fibres improved the Young modulus of the blends, creating a concomitant loss in percent elongation (El) and ultimate tensile strength. Fiber content above 40% impacted tensile property negatively and composites with over 70% fiber contents composites were too fragile. Data suggest that macro algae are compatible with both polymers and processable as fillers in hybrid blends. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Dispersion evaluation of microcrystalline cellulose/cellulose nanofibril-filled polypropylene composites using thermogravimetric analysis

Microcrystalline cellulose-filled polypropylene (PP) composites and cellulose nanofiber-filled composites were prepared by melt blending. The compounded material was used to evaluate dispersion of cellulose fillers in the polypropylene matrix. Thermogravimetric analysis (TG) and mechanical testing were conducted on composites blended multiple times and the results were compared with single batch melt blended composites. The residual mass, tensile strength, and coefficient of variance values were used to evaluate dispersion of the microcrystalline cellulose fillers in the PP matrix. The potential of using TG to evaluate cellulose nanofiber-filled thermoplastic polymers was also investigated and it was found that the value and variability of residual mass after TG measurements can be a criterion for describing filler dispersion. A probabilistic approach is presented to evaluate the residual mass and tensile strength distribution, and the correlation between those two properties. Both the multiple melt blending and single batch composites manufactured with increased blending times showed improved filler dispersion in terms of variation and reliability of mechanical properties. The relationship between cellulose nanofiber loading and residual mass was in good agreement with the rule of mixtures. In this article, the authors propose to use a novel method for dispersion evaluation of natural fillers in a polymer matrix using TG residual mass analysis. This method can be used along with other techniques such as scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD) for filler dispersion evaluation in thermoplastic composites.     

Mechanical and thermal investigation of thermoplastic nanocomposite films fabricated using micro- and nano-sized fillers from recycled cotton T-shirts

The thermal and mechanical performance of composites with nano-sized cotton fillers embedded in low-density polyethylene (LDPE) is investigated. Microfibrillated cotton was prepared by microgrinding mechanical treatment of pulverized cotton (pCot) derived from waste T-shirts, resulting in nano-sized fibrils of the cellulose that retain high crystallinity. Film composites of LDPE with pCot before and after microgrinding were fabricated through melt extrusion and the effect of filler size on mechanical, thermal and morphological properties of the composite was investigated. Compounding microfibrillated cotton with LDPE resulted in well-dispersed nanocomposites with no discoloration after 10 min of melt extrusion at 170 °C. At concentrations up to 10 % by weight, the composites showed increased modulus, increased tensile strength and a slight decrease in elongation to break. Further improvement in the dispersion and mechanical properties of the cotton-based fillers was realized by the use of LDPE powder instead of polymer pellets fed to the extruder. This research demonstrates the processing and applicability of the use of recycled cotton-based nano-sized fillers in melt-processing.