Maleated Natural Rubber as a Coupling Agent for Recycled High Density Polyethylene/Natural Rubber/Kenaf Powder Biocomposites

Kenaf powder (KP) was incorporated into recycled high density polyethylene (rHDPE)/natural rubber (NR) blend using an internal mixer at 165°C and rotor speed of 50 rpm. The tensile strength and elongation at break of the composites decreased, while the tensile modulus increased with increasing filler loading. The water absorption was found to increase as the filler content increased. The maleic anhydride grafted natural rubber was prepared and used to enhance the composites performance. The addition of MANR as a coupling agent improved the tensile properties of rHDPE/NR/KP biocomposites. The water absorption was also reduced with the addition of MANR.     

Effect of coir fiber loading on mechanical and morphological properties of oil palm fibers reinforced polypropylene composites

Hybrid composites were fabricated by compounding process with varying the relative weight fraction of oil palm empty fruit bunch (EFB) and coir fibers to assess the effect of hybridization of oil palm EFB with coir fibers in polypropylene (PP) matrix. The mechanical and morphological properties of oil palm/coir hybrid composites were carried out. Tensile and flexural properties of oil EFB‐PP composites enhanced with hybridization of coir fibers except coir/oil palm EFB (25:75) hybrid composite, whereas highest impact properties at oil palm:coir fibers with 50:50 ratios. Results shown that hybrid composites with oil palm:coir fibers with 50:50 ratios display optimum mechanical properties. In this study, scanning electron microscopy (SEM) had been used to study morphology of tensile fractured surface of hybrid composites. Its clear from SEM micrograph that coir/EFB (50:50) hybrid composites display better tensile properties due to strong fiber/matrix bonding as compared with other formulations which lead to even and effective distribution of stress among fibers. The combination of oil palm EFB/coir fibers with PP matrix produced hybrid biocomposites material can be used to produce components such as rear mirrors' holder and window levers, fan blades, mallet, or gavel. POLYM. COMPOS., 35:1418–1425, 2014. © 2013 Society of Plastics Engineers     

Preparation and characterization of composites based on polyhydroxybutyrate and waste powder from coconut fibers processing

Polyhydroxybutyrate (PHB) is a thermoplastic, biodegradable, linear, and semicrystalline polyester synthesized by bacteria; while coir dust, a waste generated during the coconut fiber processing, is a mixture of short fibers and powder. The aim of this work was to prepare and characterize composites based on a biopolymer and biowaste, so that the products were derived from natural renewable resources. The composites were produced by compression molding. Composite properties were evaluated by scanning electron microscopy, low field nuclear magnetic resonance, X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and tensile tests. The best results were obtained for the composite containing 10 wt% coir dust, which presented improvements of 35% in tensile strength and 25% in elongation at break when compared with unfilled PHB. The dispersion of higher contents of filler was inefficient resulting in agglomeration and consequently, in premature failure. Despite hydrophilic nature of the coir dust, some degree of interaction between filler and polymeric matrix occurred. It was suggested that coir dust plays two simultaneous roles in the composite. Initially, the filler surface would favor crystal formation acting as a nucleating agent, and at the same time, chain movements would be progressively hindered inhibiting crystal growth. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Effect of filler surface treatment on the properties of recycled high‐density polyethylene/(natural rubber)/(Kenaf powder) biocomposites

Biocomposites were prepared from a kenaf core powder and recycled high‐density polyethylene/(natural rubber) blend by using an internal mixer at 165^oC and 50 rpm. The effect of the filler content and the filler surface treatment was studied. Chemical modification of kenaf filler was performed with alkali pretreatment followed by treatment with silane. Scanning electron microscopy and infrared spectroscopy studies confirmed changes in the chemical compositions and structural characteristics induced through the modification. It was found that treated biocomposites offered higher tensile strength and tensile modulus, but lower elongation at break compared with untreated biocomposites. Lower water absorption and higher thermal stability of the resultant biocomposites were also obtained when treated fillers were used. J. VINYL ADDIT. TECHNOL., 20:218–224, 2014. © 2014 Society of Plastics Engineers     

Properties of silanized nypa fruticans filled polylactic acid/recycled low density polyethylene biocomposites

The biocomposites of Nypa Fruticans (NF) and Polylactic acid (PLA)/recycled low density polyethylene (rLDPE) were prepared using Brabender EC PLUS. The effect of NF content and silane coupling agent on mechanical, thermal, and morphological properties were studied. The results show that addition of NF in PLA/rLDPE biocomposites have decreased the tensile strength, elongation at break, and crystallinity of biocomposites. The Young's modulus of biocomposites and thermal stability increased with the increasing NF content. The surface of NF fillers were silanized to improved the interfacial adhesion between the NF filler and PLA/rLDPE matrix. It was found that the tensile strength, Young's modulus, crystallinity of PLA, and thermal stability of silanized biocomposites higher as compared to untreated biocomposites. The enhancement of the properties of biocomposites with silane treatment was proven by SEM studied. The silanized biocomposites showed better interfacial interaction and adhesion between NF and PLA/rLDPE matrix. POLYM. ENG. SCI., 55:1733–1740, 2015. © 2014 Society of Plastics Engineers     

Jatropha deoiled cake filler‐reinforced medium‐density polyethylene biocomposites: Effect of filler loading and coupling agent on the mechanical,dynamic mechanical and morphological properties

This work focuses on the performance of Jatropha deoiled cake (JOC) as filler for medium‐density polyethylene. The biocomposites were prepared using a melt‐compounding technique. Maleated polyethylene (MPE) was used as a reactive additive to promote polymer/filler interfacial adhesion. The mechanical, thermodynamic mechanical and morphological properties of the resultant composites were investigated. The results show that the incorporation of JOC into the matrix reduced tensile, flexural, and impact strengths compared with the pure matrix. Moreover, tensile and flexural moduli were increased. The composites prepared with MPE had better mechanical properties and lower water uptake, indicating an enhancement in the interfacial interaction between JOC and polyethylene systems. The storage modulus was increased by the increase in filler loading and decreased when MPE was used. The composites loss modulus curves revealed two glass transitions indicating partial miscible blends. Scanning electron microscopy analysis for maleated composites showed a relatively homogeneous morphology with few left cavities, and the filler particle size is smaller compared to nontreated composites. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Influence of fly ash cenospheres on performance of coir fiber‐reinforced recycled high‐density polyethylene biocomposites

Recycled high‐density polyethylene (RHDPE)/coir fiber (CF)‐reinforced biocomposites were fabricated using melt blending technique in a twin‐screw extruder and the test specimens were prepared in an automatic injection molding machine. Variation in mechanical properties, crystallization behavior, water absorption, and thermal stability with the addition of fly ash cenospheres (FACS) in RHDPE/CF composites were investigated. It was observed that the tensile modulus, flexural strength, flexural modulus, and hardness properties of RHDPE increase with an increase in fiber loading from 10 to 30 wt %. Composites prepared using 30 wt % CF and 1 wt % MA‐g‐HDPE exhibited optimum mechanical performance with an increase in tensile modulus to 217%, flexural strength to 30%, flexural modulus to 97%, and hardness to 27% when compared with the RHDPE matrix. Addition of FACS results in a significant increase in the flexural modulus and hardness of the RHDPE/CF composites. Dynamic mechanical analysis tests of the RHDPE/CF/FACS biocomposites in presence of MA‐g‐HDPE revealed an increase in storage (E′) and loss (E″) modulus with reduction in damping factor (tan δ), confirming a strong influence between the fiber/FACS and MA‐g‐HDPE in the RHDPE matrix. Differential scanning calorimetry, thermogravimetric analysis thermograms also showed improved thermal properties in the composites when compared with RHDPE matrix. The main motivation of this study was to prepare a value added and low‐cost composite material with optimum properties from consumer and industrial wastes as matrix and filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42237.     

Effective reinforcement of hydrogen-bonding assembly silica-graphene hybrid in natural rubber

Silica-graphene hybrid (HGKS) with good dispersion and strong interfacial interactions was fabricated by hydrogenbonding assembly. HGKS was incorporated into natural rubber (NR) to develop high-performance tire treads. During vulcanized process of HGKS filled NR (NR/HGKS), HGKS can participate in the process to form dual dynamic network structure. The interfacial interaction between HGKS and NR due to the dispersion of HGKS was investigated. The strong covalent interaction between NR and HGKS is the most important factor to determine the ultimate performance of rubber composites. In this contribution, a series of HGKS with different hybrid grafting ratio are prepared to reveal the effects of changes in filler surface properties on the structure and mechanical properties of rubber composites. It has been demonstrated that it is an effective hybrid technique to drastically improve its dispersibility in NR and form strong interfacial reactions, and HGKS is expected to be used as a new type of reinforcing filler for the manufacture of high-performance green tire materials.     

Transport of organic solvents through coir-fiber-reinforced natural rubber composites: a method for evaluating interfacial interaction

Use is made of the transport of organic solvents such as benzene, toluene and xylene to understand the interfacial interaction in cross-linked coir-fiber-reinforced natural rubber composites. Attempts were made to analyze the interfacial bonding in the composites containing coir fibers subjected to different chemical treatments. Based on experiments, a probable mechanism of transport is suggested. The diffusion coefficient and solubility in the rubber compound–solvent system have been evaluated. The swelling of composites containing untreated and NaOH-treated coir increased initially with fiber loading, but decreased at higher levels of fiber loading. But the swelling of composites which contained coir fiber treated with solutions of NaOH, toluene diisocyanate and natural rubber decreased gradually with fiber loading. It was also found that the swelling of this composite was the least. This is due to the high interfacial interaction between the fiber and the matrix which resists the uptake of organic solvents. It was seen that silica was not a necessary constituent of the bonding system for coir fiber reinforced natural rubber composites.     

Fracture properties of natural rubber filled with hybrid carbon black/nanoclay

Hybrid carbon black (CB) and nanoclay (NC) in a rubber matrix have provided superior mechanical performances over conventional composites. Yet the fracture and fatigue properties have not been fully explored. In this paper, the mechanical properties of the hybrid-filled natural rubber (NR) were investigated with regard to the tensile strength, fatigue crack growth (FCG) and cut resistance. The ruptured crack tip and the torn surface were studied by using optical microscopy and scanning electron microscopy (SEM), respectively. It was found that the fatigue resistance at large tearing energy and cut strength were enhanced with hybrid filler. Subsidiary cracks were observed at the ruptured tip in rubber with NC. Morphology analysis revealed that the hybrid filler led to a rougher torn surface than rubber with non-hybrid filler. It was proposed that the clay layers constructed a dual phase filler network with CB aggregates. The filler network could cause strength anisotropy in the matrix and introduce more energy dissipation mechanisms to the system, resulting in enhanced fatigue resistance.     

Novel eco‐friendly biodegradable coir‐polyester amide biocomposites: Fabrication and properties evaluation

Biocomposites are prepared from a cheap, renewable natural fiber, coir (coconut fiber) as reinforcement with a biodegradable polyester amide (BAK 1095) matrix. In order to have better fiber‐matrix interaction the fibers are surface modified through alkali treatment, cyanoethylation, bleaching and vinyl grafting. The effects of different fiber surface treatments and fiber amounts on the performance of resulting bio‐composites are investigated. Among all modifications, cyanoethylated coir‐BAK composites show better tensile strength (35.50 MPa) whereas 7% methyl methacrylate grafted coir‐BAK composites show significant improvement in flexural strength (87.36 MPa). The remarkable achievement of the present investigation is that a low strength coir fiber, through optimal surface modifications, on reinforcement with BAK show an encouraging level of mechanical properties. Moreover, the elongation at break of BAK polymer is considerably reduced by the incorporation of coir fibers from nearly 400% (percent elongation of pure BAK) to 16‐24% (coir‐BAK biocomposites). SEM investigations show that surface modifications improve the fiber‐matrix adhesion. From biodegradation studies we find that after 52 days of soil burial, alkali treated and bleached coir‐BAK composites show significant weight loss. More than 70% decrease in flexural strength is observed for alkali treated coir‐BAK composites after 35 days of soil burial. The loss of weight and the decrease of flexural strength of degraded composites are more or less directly related.     

Improving the mechanical properties of ethylene propylene diene monomer rubber/low density polyethylene/rice husk biocomposites by using various additives of filler and gamma irradiation

In this work, ethylene propylene diene monomer rubber (EPDM)/low‐density polyethylene (LDPE) (100/60) blend was loaded with 20 phr (part per hundred parts of rubber) of rice husk to give biocomposites. To improve the compatibility of this biocomposites, 7 phr of maleic anhydride was also loaded. This biocomposite was then reinforced with 40 phr of high abrasion furnace (HAF)‐carbon black (N330) or 40 phr Hisil. Vulcanization of these biocomposites was carried out by gamma irradiation at doses from 50 to 250 kGy. The EPDM/LDPE blend and its biocomposites were characterized by studying the mechanical, physical, and thermal properties. Also examination by scanning electron microscopy (SEM) was studied. The results indicated that gamma irradiation and fillers improved the physical and mechanical properties and the thermal stability of the obtained biocomposites. The SEM micrographs confirmed the results obtained from mechanical properties. J. VINYL ADDIT. TECHNOL., 25:296–302, 2019. © 2019 Society of Plastics Engineers     

The influence of the dispersed phase on the morphology,mechanical and thermal properties of PLA/PE‐LD and PLA/PE‐HD polymer blends and their nanocomposites with TiO2 and CaCO3

This research investigated the impact of different processing temperature (extrusion at 160°C and 180°C) and the influence of the TiO₂ and CaCO₃ fillers on morphology, mechanical, and thermal properties of polylactide (PLA) blended with low‐density polyethylene (PE‐LD) and high‐density polyethylene (PE‐HD) in 90/10 weight ratio. The impact of the particle size of the filler was also examined with the three types of TiO₂ filler. It has been shown that the different processing temperature has no significant impact on the morphology, mechanical, and thermal properties of PLA/PE‐LD 90/10 and PLA/PE‐HD 90/10 polymer blends. It has also been shown that better phase interaction is not the crucial factor for the improvement of the mechanical properties but the domain size distribution of the dispersed phase within the matrix and the dispersion of the filler are. Samples with a narrow size distribution of the dispersed phase domain (5 to 10 μm) with the higher portion of larger domains that are uniformly distributed within the polymer matrix showed best mechanical properties. POLYM. ENG. SCI., 59:1395–1408 2019. © 2019 Society of Plastics Engineers     

Tribo-material based on a UHMWPE/RGOC biocomposite for using in artificial joints

Reduced graphene oxide (RGOC) filler that was green synthesized by vitamin C had been included in the ultrahigh molecular weight polyethylene (UHMWPE) matrix to produce biocomposite possessing improved properties especially against wear. The biocomposites filled with different loading (0.1, 0.3, 1.0, and 2.0 wt%) of RGOC was produced by a method of liquid phase ultrasonic mixing and then hot press molding. The structural analysis results of biocomposites showed that RGOC well-dispersed in polymer matrix and confirmed that there was interaction between the RGOC-UHMWPE. The biocomposite containing 2.0 wt% RGOC (UHMWPE/RGOC-2) gave the maximum microhardness and the value increased by 22. 5% compared with unfilled polymer. At the same RGOC content, the biocomposite had the highest thermal stability with residue content at 2.42%. The wear and friction behavior of biocomposites were carried out in a reciprocating friction testing machine under distilled water lubricating conditions. The UHMWPE/RGOC-2 biocomposite had the lowest friction coefficient value (0.034) and the wear rate of the biocomposite decreased by 44%, compared with that of unfilled UHMWPE. Furthermore, fatigue wear tracks were significantly reduced. This study suggests the use of this composite that had excellent tribological behavior as biomaterial instead of UHMWPE.     

无机化合物对填充PE薄膜性能影响的研究

以CaCO3、BaSO4、滑石粉为填料,以低密度聚乙烯(LDPE)为基体,通过共混、挤出工艺制得无机填充母粒,将填充母粒与LDPE、线性低密度聚乙烯(LLDPE)按一定比例混合,通过吹塑成型获得不同无机填料改性聚乙烯(PE)薄膜,并对其力学性能和光学性能进行了测试和分析.结果表明,CaCO3、BaSO4、滑石粉质量分数低于15%时,能增加PE薄膜的拉伸强度,而且BaSO4、滑石粉改性PE薄膜的光学性能比CaCO3改性PE薄膜效果好.     

Fabrication of nonextruded recycled rubber–polyethylene composites

This study was conducted to investigate the possibility of one-stage molding process skipping compounding extrusion for the fabrication of cross-linked polyethylene (PE)-ground tire rubber (GTR) composites. The process resulted in a wide range of composites with various properties. Response surface methodology technique based on central composite design was employed with variables: polyethylene content (PE: % per polymer fraction), dicumyl peroxide (DC: % per polymer fraction), molding residence time (RT: min), and filler content (F: % per total mass). A quadratic model was able to significantly describe tensile strength, elongation at break (EB), and impact resistance/energy of the composites as a function of PE, DC, RT, and F. Tensile strength (TS) was positively affected by PE, DC, and RT; however, it was negatively affected by the filler content. Tensile EB and impact resistance of the composites were improved by DC and RT, while reduced by PE and filler increment. Composites with TS, ultimate elongation, and impact resistance of 11.5 MPa, 140%, 244 MJ/m², respectively, were obtained under optimized conditions. The nonextrusion molding process is recommended for the fabrication of PE-GTR composites due to the higher stiffness/tensile modulus and a slightly lower strength of nonextruded composites compared to the extruded composites.     

Biopolymers as effective fillers in natural rubber: Composites versus biocomposites

Biocomposites of natural rubber (NR) blends were prepared with a variety of fillers obtained from renewable resources by a mastication technique. They were characterized for their mechanical properties and morphologies and compared with composites of the conventional filler carbon black (c‐black). The biopolymers exhibited an interesting trend and imparted strength to NR that was quite comparable to c‐black. Up to 30 phr of the fillers could be successfully incorporated; this led to enhancements in the mechanical strength. The properties were found to vary with the type and ratio of filler, namely, starch, cellulose, and chitin. The optimum mechanical strength of the biocomposites was observed at 10 phr. The results were interpreted on the basis of the morphology by scanning electron microscopy, which revealed strong filler–polymer interactions. The moisture‐uptake characteristics of the composites were studied. It was found that addition of biofillers did not lead to a significant increase in the moisture absorption. Furthermore, as the adhesion between the polymer matrix and fillers increased, the water uptake decreased. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Assembly of layered double hydroxide on multi‐walled carbon nanotubes as reinforcing hybrid nanofiller in thermoplastic polyurethane/nitrile butadiene rubber blends

An efficient approach has been applied to assemble MgAl layered double hydroxide onto pristine carbon nanotubes using sodium dodecylsulfate. The assembling process and formation of such hybrid nanostructures were established using X‐ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and high‐resolution transmission electron microscopy. Subsequently, the hybrid was used as nanofiller in the development of high‐performance thermoplastic polyurethane/acrylonitrile butadiene rubber (1:1 w/w) blend nanocomposites. Measurements of mechanical and dynamic mechanical properties show that tensile strength, elongation at break and storage modulus improve significantly by 171%, 1.8 times and 241% in a blend with 0.50 wt% loading of hybrid filler. Thermogravimetric analysis shows that the thermal stability of the blend with 0.50 wt% hybrid filler compared to neat material is maximally improved by 20 °C determined at 50% weight loss. Differential scanning calorimetry shows the maximum enhancement in melting temperature (7 °C) and crystallization temperature (31 °C) due to significant nucleation efficiency of the filler, homogeneous dispersion and strong interfacial interaction between polymer matrix and filler. © 2015 Society of Chemical Industry     

Compatibilization of natural rubber–polyolefin thermoplastic elastomeric blends by phase modification

Natural rubber–polyolefin (70/30) blends have been studied by incorporation of modified rubber and plastic phases with a view to make the heterogeneous phases compatible. The modified rubbers used were epoxidized natural rubber (ENR) and sulfonated ethylene–propylene diene rubber (S-EPDM) at a level of 20 parts. Other rubbers such as chlorinated polyethylene (CPE) and ethylene propylene diene rubbers (EPDM) were also used at a level of 20 parts in the natural rubber–polyethylene (NR/PE) systems. The plastic phase was chemically modified with maleic anhydride (MA) in presence of benzoyl peroxide (BPO) and used at a concentration of 10% of PE, i.e., PEm. The tensile properties such as the modulus, elongation at break, tensile strength, and hysteresis were studied. NR/ENR/PEm/PE shows the greatest improvement in tensile strength (45% over control NR/PE). NR/S-EPDM/PEm/PE also shows similar improvement, although the hysteresis loss decreases. The change in these properties could be related to the adhesive strength. This was found to be improved by the incorporation of modified rubber and modified plastic phases. The best adhesion values have been obtained with NR/ENR/PEm/PE and NR/S-EPDM/PEm/PE. Thus, a correlation between tensile and adhesive strength was obtained for all the systems. The increase in adhesive strength is due to chemical reactions between the various phases. Probable chemical reactions have been suggested. Morphological observations show that the phases are interpenetrating, and this is consistent with the increased tensile strength. The natural rubber–polypropylene (NR/PP) systems do not offer good strength properties with the modified PP and modified rubbers. The adhesive strength also decreases with the incorporation of the modified system. The hysteresis properties show some improvement.     

Preparation and characterization of chitosan/KSF biocomposite film

Chitosan–clay biocomposites have been prepared in which KSF‐montmorillonite (KSF) is used as filler and diluted acetic acid is used as solvent for dissolving and dispersing chitosan and montmorillonite, respectively. The effect of KSF loadings in biocomposites has been investigated. The characterization with different methods (FTIR, DSC, TGA, SEM, and XRD) on chitosan/KSF biocomposites systems was examined. Morphology and properties of chitosan biocomposites have been studied compared with those of pure chitosan. The FTIR and SEM results indicated the formation of an intercalated‐and‐exfoliated structure at low KSF content and an intercalated‐and‐flocculated structure at high KSF content. The thermal stability and the mechanical properties of the composites were also examined by DSC, TGA/DTG, and tensile strength measurements, respectively. The dispersed clay improves the thermal stability of the matrix systematically with the increase of clay loading. Tensile strength of a chitosan film was enhanced until the clay ratio up to 2 wt% and elongation‐at break decreased with addition of clay into the chitosan matrix. The XRD results confirmed the intercalation of the biopolymer in the clay interlayer by the decrease of 2θ values while the chitosan–clayratio increases. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers