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The development of smart polymer nanocomposites (SPN) has been an area of high scientific and industrial interest in recent years, due to fantastic improvements achieved in these materials. SPN found potential applications in shape memory, self-healing, self-sensing, self-heating, self-cleaning, and energy harvesting. This mini-review highlights the current research and development on SPN, specifically on shape memory polymer (SMP) and self-healing polymer (SHP) nanocomposites. The processing techniques for SPN nanocomposites, for example, polymerization, melt-compounding, solution mixing, electrospinning, and thermoset-curing are discussed. Some of the potential strategies to modify the properties of SMP and SHP nanocomposites are highlighted. The future perspective and recommended works for the SPN nanocomposites are shared in this mini-review.

Non-woven flax fibre reinforced acrylic-based polyester (NFA) composites were prepared using an impregnation process. A mixture of acrylic-based polyester (Acrodur®) with varying sodium silicate (SS) loadings was applied to impregnate the non-woven flax fibre mat. Flexural tests were performed to evaluate the mechanical properties of the composites. Flammability properties were assessed via UL94 test and limiting oxygen index (LOI). The mechanical properties of NFA composites decreased substantially with increment in SS loading. The addition of SS resulted in significant improvement of flame retardancy, whereby UL94 rating enhanced from V-1 to V-0, while the LOI values increased from 24 to 40. Sound absorption coefficients of the NFA composites were measured via two-microphone transfer function technique in impedance tube. The sound absorption properties of NFA composites also improved with the incorporation of SS, whereby the sound absorption coefficient increased up to 0.87 at 2000 Hz frequency. Based on the overall evaluation, 20 wt% of SS effectively increased flame retardancy and sound absorption properties, along with moderate deterioration in flexural properties. The scanning electron microscopic (SEM) analysis of the composites surfaces displayed formation of voids and irregular structures at higher SS loading, which reduced the mechanical properties of NFA composites. The SEM images offered supportive evidences on the role of hollow lumen structures in natural fibres to ensure better sound absorption performance in NFA composites.

Biodegradable polymers, especially bacterial synthesized polymers, have gained great attention and interest due to the concerns raised regarding the accumulation of petrochemical plastic wastes in the environment. It is known that biodegradable polymers have advantages such as being biocompatible, biodegradable, natural, renewable and have similar mechanical properties compared to conventional polymers. Poly(hydroxybutyrate) (PHBs) are biodegradable polyesters produced naturally by bacteria. PHBs are highly crystalline polyester, which are brittle and prone to thermal degradation during processing. In the past, attempts have been made to reduce the degree of the brittleness of the PHB by copolymerization with hydroxyhexanoate (HHx) or hydroxyvalerate (HVx) co-monomers. Among PHB copolymers: poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-co-HHx), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) have improved the flexibility and mechanical properties more than other PHBs. This chapter aims to emphasize the potential on the compatibilization of biodegradable polymer blends with the presence of maleated compatibilizers derived from the host or guest polymers.

This study assesses the nature of absorbed moisture and the correlation with hygrothermal effects in fiber-reinforced polymer (FRP) performance. Three types of fiber arrangement which is kenaf fiber and unsaturated polyester (UPE) only, kenaf fiber roving co-reinforced glass fiber chopped strand mat with UPE and kenaf fiber roving co-reinforced with fiber glass-oriented mat with UPE. All specimens were fixed at 0.50 Vf to make a fair comparison and validity results of further testing. As aware, GFRP has the highest mechanical properties which are superior compared to other samples of composite and KFRP shows the lowest mechanical properties. Hygrothermal conditions were achieved by immersing samples at a constant temperature of distilled water at 70°C for 1, 4 and 7 days hence results in the same trend of performance with unconditioned tests. However, all samples have certain percentage retention of mechanical strength after re-dried in an oven at 70°C for 24 hours to remove all the moisture in the samples. Water absorption is then were analyzed to determine the diffusion parameters of all samples. The flexural test was conducted to determine the durability and to measure its mechanical strength under a hygrothermal environment. FTIR proves the presence of water within the UPE matrix. Morphological analysis using confocal laser imaging and field emission scanning electron microscopy FESEM showing evidence by a clear picture of samples that undergo deterioration.

The objective of this research article is to study the mechanical and tribological properties of polytetrafluoroethylene filled carbon fiber reinforced polycarbonate (SCF/PC/PTFE) composites. The mechanical test include tensile and flexural properties. The fiber length distributions were conducted using acid digestion method, while the tribology test using pin-on-disk configuration. Several composition of PC based matrix with SCF as the reinforcement and PTFE as the dispersed phase were studied. The samples were prepared by mean of single screw extrusion and injection molding processes. The results showed that as CF are added, tensile and flexural strength increases. Whilst the addition of PTFE shows negative impact on both tensile and flexural. its influence on wear rate and coefficient of friction is very promising. The incorporation of CF and PTFE into PC show effective tribology-improving capabilities. The combinative effect of CF and PTFE are shown to be able to further enhance the friction and wear properties of PC matrix.

Poly(lactic acid) (PLA)/halloysite nanotube (HNT) nanocomposites were prepared using melt compounding followed by compression molding. Maleic anhydride grafted styrene–ethylene/butylene–styrene copolymer (SEBS-g-MA) and N,N′-ethylenebis(stearamide) (EBS) were used to improve the impact properties of PLA nanocomposites. The properties of PLA/HNT nanocomposites were characterized by tensile and impact tests, Fourier transform infrared spectroscopy, thermal analysis (DSC and TGA), and morphological analysis (FESEM and TEM). In addition, the oxidation onset temperature (OOT) was determined using DSC. The PLA/HNT6/EBS5 nanocomposites gives higher impact strength improvement (98%) compared to that of PLA/HNT6/SEBS-g-MA5 (77%). Also, the PLA/HNT6/EBS5 exhibited higher OOT compared to that of PLA/HNT6/SEBS-g-MA5 nanocomposites.

This paper reports on the comprehensive characterisation of heat treated kenaf fibre (KF) and its composites. The kenaf fibres were modified by heating for 2.5–12.5 h inside a drying oven. Heat treatment produces an increase in the crystallinity index and fibre strength of KF. The highest value of KF strength was recorded by applying heat treatment of 10 h on KF. The heat treatment results in the partial removal of impurities/extractives on the KF surface which is detected by scanning electron microscopy and X-ray photoelectron spectroscopy. Atomic force microscopy results signify the decrease of roughness, the increase in peak area density and the increase of the adhesion force on the surface area of heat treated KF. The effect of the heat treatment in enhancing the interface bonding characteristics between the KF and unsaturated polyester matrix can be reflected by the interlaminar shear strength (ILSS) and dynamic mechanical analysis value of the composites. The flexural properties of the compo...

The hygrothermal effect on unsaturated polyester composites containing 30% by volume of untreated and alkali treated nonwoven kenaf fiber along with neat resin have been studied. The kinetics of water uptake was investigated by immersing neat resin and composites at room temperature, 60°C and 90°C. Alkali treatment significantly reduced the water uptake and the diffusivity of composite at all aging temperatures; thereby the alkali treated kenaf fiber composites showed better durability of flexural properties. Elevated temperatures aging promoted the severe degradation of samples, and subsequent drying could not restore the flexural properties.

Poly(lactic acid) (PLA)/halloysite nanotube (HNT) nanocomposite thin films were prepared via melt compounding followed by compression molding. Epoxidized natural rubber (ENR) was used to toughen the PLA/HNT nanocomposites. The effects of the HNTs and ENR on the oxygen permeability of the PLA films were evaluated. The oxidation onset temperatures (OOTs) of the PLA nanocomposites were measured using differential scanning calorimetry (DSC), and the thermal decomposition was assessed by thermogravimetric analysis (TG). PLA/HNT6/ENR5 exhibits the lowest oxygen permeability coefficient of the films studied, which indicates that the barrier properties of PLA/HNT6 were enhanced by the incorporation of 5 mass% ENR. From the DSC results, the addition of 6 mass% HNT shifted the OOT of the PLA to higher temperatures, improving the antioxidant properties of the PLA nanocomposites. The thermal decomposition behavior of the PLA/HNT nanocomposites depends on the HNT loading, ENR loading, and testing environment (i.e., nitrogen and oxygen). The TEM images suggest that ENR promoted good interaction between the PLA and HNT, which confirms that good adhesion between HNT and ENR generates longer tortuous pathways for oxygen permeation and results in a PLA/HNT nanocomposite with enhanced barrier properties.

In this paper, the mechanical performance of resin transfer moulded nonwoven kenaf fibre/epoxy composites in the fibre volume fraction ( V f) range of 0–0.42 was investigated. The effect of the needle-punching direction on the tensile properties of the composites was also investigated. The highest tensile, flexural and fracture properties were attained at a V f of 0.42. The nonwoven kenaf fibre/epoxy composites were proven to exhibit tensile isotropy. The typical load versus displacement graph and scanning electron microscopy micrographs of the epoxy and nonwoven kenaf fibre/epoxy composites revealed that the energy absorbing events caused by the fibres led to improvements in the fracture toughness. Meanwhile, the micromechanical parameters of the composites were determined by a micromechanics analysis using the Cox–Krenchel model. The analysis proved the applicability of the model for nonwoven kenaf fibre/epoxy composites as the calculated efficiency factors were comparable to the values from previous literatures.

Poly(lactic acid)/halloysite nanoclay (PLA/HNC) nanocomposites with N, N′-ethylenebis(stearamide) (EBS) were produced by melt mixing. Water absorption behaviors of the PLA nanocomposites were studied at three different temperatures, that is, 30, 40, and 50°C. The water absorption kinetics of PLA/HNC nanocomposites conform to Fickian diffusion behavior at immersion temperatures of 30 and 40°C due to the diffusional exponent ( n) values that were close to 0.5 for all specimens. However, the hydrolysis of PLA occurred for longer time deviations at 50°C. Activation energy of water diffusion ( Ea) for PLA nanocomposites were found to be affected by the HNC and EBS contents. The glass transition temperature ( Tg), cold crystallization temperature ( Tcc), and melting temperature ( Tm) of the PLA sample were shifted to lower temperature after subjected to immersion temperature of 50°C. The carbonyl index of all PLA specimens increased after water absorption at 40 and 50°C due to the formation of higher amount of carboxylic acid end groups during the hydrolysis process.

In this work, nonwoven kenaf fibre/epoxy composites were produced by using resin transfer moulding. The effect of kenaf fibre volume fraction on the composites’ tensile properties and Poisson’s ratio was investigated. Experimental results show that highest tensile properties and Poisson’s ratio were attained at volume fraction = 0.42. A simple method has been developed to predict the fibre transverse modulus and has allowed the characterisation of kenaf fibre’s elastic anisotropy. The performance of the Tsai–Pagano model in predicting the composites’ tensile modulus and Poisson’s ratio was compared with the Manera and Cox-Krenchel model. Results showed that the consideration of fibre’s elastic anisotropy in the Tsai–Pagano model yielded a good prediction of both composites’ modulus and Poisson’s ratio. Meanwhile, the Bowyer–Bader model produced a better tensile strength prediction owing to the inclusion of fibre length and orientation factors in the model.

The use of glass fibre in the production of fibre reinforced polymer composites industries is no longer acceptable as far as environmental pollution is concern. Therefore, the introduction of kenaf fibre as reinforcement materials in the production of composites is expected to lessen the use of current synthetic materials especially glass fibre. This research reported the performance of pultruded kenaf fibre reinforced composites after exposed to natural weathering condition up to 200 days. Three different linear mass density (Tex) of kenaf yarn fibre i.e. 1400, 2200 and 3300 g/km were used as reinforcement material in producing the pultruded composite samples. Moisture content of each composites was recorded over exposure time and the changes of mechanical properties i.e. flexural and compression properties were also recorded. It was found that sample made of 3300 linear mass density recorded higher moisture absorption as compared to sample with 1400 linear mass density. The flexural and compression properties consistently decreased throughout the exposure period as the absorption of moisture into the composites had weakened the interfacial bonding between the kenaf fibre and the matrix resin. The research outcomes show that for a given yarn architecture, lower linear mass density of fibre gives better moisture resistance and retain greater mechanical properties over the period of exposure. This study suggests that linear mass density is an important factor to be considered when pultrusion process in concern.

Today, massive increase in the usage of plastic products leads to environmental pollution. To worsen the situation, biodegradable materials alone will not satisfy some properties required by the industries. Therefore, in this research, blends of biodegradable polybutylene(succinate)(PBS)/thermoplastic polyurethane(TPU) polymer blend were developed, with the aim of getting a biodegradable material with improved properties. The idea of selecting TPU as the second component is mainly to improve the toughness.It is also motivated by the advantages it offers such as good abrasion resistance, good mechanical properties with rubber-like elasticity as well as good tear resistance.The aims of the present study are to show the effect of blend ratios on the mechanical and morphology properties and identify the optimum weight ratio for PBS/TPU. Effect of various weight ratios (30wt%, 50wt% and 70 wt%) TPU addition into PBS were studied. Tensile test were examined in order to determine the best weight ratio PBS/TPU blend. Scanning electron microscope (SEM) and differential scanning calorimetry (DSC) were used to examine compatibility and miscibility of the blends. The results from this work show that high weight ratio of PBS will influence high mechanical properties of the blend. PBS/TPU (70:30) have highest tensile modulus and strength compare to lower PBS concentration. SEM and DSC results were shown to support the tensile modulus and strength.

As there has been an increasing trend in using nonwovensnatural fiber in composites, there is a need to find good micromechanical models to represent their behavior. In this study,randomly oriented nonwoven kenaf/epoxy composites at various fiber loading has been fabricated by using resin transfer moulding (RTM) method. Experimental results show that increasing the fiber loading has led to the increment of tensile modulus. The validity of rule of mixtures (ROM) and modified rule of mixtures (MROM) which includes model by Krenchel and Nairn has also been analyzed. ROM has failed to predict the tensile modulus of the composites. Meanwhile, MROM managed to produce an accurate tensile modulus prediction due the inclusion of fiber length factor by Nairn model and fiber orientation factor by Krenchel model.

Response surface methodology (RSM) was used to determine the effects of high pressure homogenization (HPH) parameters (pressure and number of cycles) on the isolated yield, crystallinity, and diameter of kenaf bast cellulose nanofibers (CNF). Central composite design of experiments was utilized to determine the optimal pressure and number of cycles of HPS for the highest CNF yield, crystallinity, and lowest CNF diameter. The linear terms for the pressure and homogenization cycles had significant effects on the CNF yield, crystallinity, and diameter, whereas the interaction between the pressure and homogenization cycles had a significant effect on the CNF crystallinity. The optimized experimental conditions for the HPH process were a homogenization pressure of 56 MPa, 44 P homogenization cycles, and a 0.1 wt% fiber suspension concentration. Under these conditions, the isolated kenaf bast CNF yield was 89.9% with 56.5% CNF crystallinity and a CNF diameter of 8 nm.

Kenaf fibres of different aspect ratios (L/D = 30 and 160) were melt compounded in an internal mixer with two types of starch-grafted-polypropylene matrices (G906PF and G906PJ) at various loadings, i.e. 10, 20 and 30 wt%. The compound was then compression-moulded into plaques of 1-mm thickness. Thermal, rheological and dynamic mechanical properties of the composite samples were investigated by several techniques involving differential scanning calorimetry, thermogravimetric analysis, melt flow index, Vicat softening point and dynamic mechanical thermal analysis. The results indicated that both thermal and mechanical properties of the composites were remarkably improved by kenaf fibres. Loss modulus and loss factor showed a shift of peak transitions to higher temperatures. Finally, the properties of the investigated composite materials were not affected by the fibre aspect ratio.

Free-standing carbon nanotubes (CNTs) film known as buckypaper is a method used to address dispersion problems of CNTs. Unique properties of CNTs made the CNTs buckypaper to be considered as promising reinforcement materials in development of high-performance of nanocomposites. Buckypaper was fabricated by dispersing multi-walled carbon nanotubes (MWCNTs) in two different types of solution namely Triton X-100 and ethanol then followed by filtration process. In this study, MWCNTs loading and pressure used during filtration process were manipulated. The morphology, thermal and electrical conductivity of the buckypaper produced was studied.

This paper reports on comprehensive characterization of wettability and interfacial properties of kenaf fibers (KF) and its unsaturated polyester (UPR) composites fabricated by resin transfer molding (RTM). KF were chemically modified by immersing in 6% NaOH concentration for 1, 2, 3, 4, and 5 h to enhance the interaction between KF and UPR. FTIR spectral data showed the chemical changes in KF after treatment which induced the modification of physical and wettability characteristics of KF. The changes in crystalinity index (CrI) and thermal stability of KF content were analyzed using X-ray diffraction (XRD) and thermogravimetry (TGA) techniques, respectively. Scanning electron microscope (SEM) shows a cleaner KF surface upon KF treatment and atomic force microscopy (AFM) signify an increasing in available fiber–matrix specific contact area. Wettability of KF was investigated by means of surface energy measurement using Washburn contact angle principle via Owens–Wendt–Rabel–Kaelble (OWRK) method. Surface energy was found to increase with longer soaking time. The effect of soaking time of alkaline treatment in enhancing the interface bonding characteristic between the KF and UPR matrices can be reflected by the ILSS value of the composites. The highest value of ILSS was recorded by 3 h treated KF composite. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

In the present study, mechanical and water absorption properties of the nonwoven kenaf fiber (KF)/unsaturated-polyester composites manufactured by resin transfer molding were investigated. Nonwoven KF mats with an aerial density of 1350 g/m2 were treated with a 6% NaOH solution for 3 h. The influence of the fiber treatment on the properties of the composites was investigated with Fourier transform-infra red (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM), and dynamic contact angle technique (DCAT). Mechanical properties measurements were conducted via determination of flexure and fracture toughness. A general trend was observed whereby alkalized KF composites gave superior mechanical properties compared to as-received KF composites. The XRD and DCAT results indicated an enhancement of the crystallinity index and surface energy of the alkali-treated KF. SEM and AFM of the treated KF showed the removal of impurities and a reduction of roughness on the KF surface with alkalization. Water immersion induced a drastic loss of the mechanical properties of the composites albeit better retention of properties was observed in the case of alkalized KF composites. The fracture surfaces were inspected by SEM which confirmed the quality of the interface. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

This paper focuses on the study of the effect of chemical treatments of fibres by alkalization on the flexural and impact properties of epoxy matrix composites reinforced by kenaf fibre (KF) produced via resin transfer moulding (RTM) technique. The reinforcement consists of KF nonwoven fiber mat fabricated using needle punching method. Prior to punching process, KF are subjected to alkali treatments with Sodium hydroxide (NaOH) at 3, 6 and 9% for a period of 3h at room temperature. The composites were reinforced with kenaf nonwoven mat at 40% by volume. Effect of alkaline treatment concentration to wettability of KF towards epoxy resins are measured by means of contact angle and surface energy analysis. Influences of alkaline treatment on the flexural properties are studied to determine the optimum conditions of alkaline treatment. As concentration of NaOH in alkaline treatment increased, the experimental results show that the flexural properties of composites increases. For 6% NaOH treatment, the flexural strength and flexural modulus improved by 7.88 MPa to 81.38 Mpa and from 4.79 GPa to 5.41GPa compared to untreated fibre composites. However, as the concentration of NaOH increase to 9%, the bending properties reduced significantly.

Polymer blend nanocomposites have been considered as a stimulating route for creating a new type of high per- formance material that combines the advantages of polymer blends and the merits of polymer nanocomposites. In nanocomposites with multiphase matrices, the concept of using nanofillers to improve select properties (e.g., mechanical, thermal, chemical, etc) of a polymer blend, as well as to modify and stabilize the blend morphology has received a great deal of interest. This review reports recent advances in the field of polyamide (PA) blend-based nanocomposites. Emphasis is placed on the PA-rich blends produced by blending with other thermoplastics in the presence of nanofillers. The process- ing and properties of PA blend-based nanocomposites with nanofillers are discussed. In addition, the mechanical properties and morphology changes of PA blends with the incorporation of nanofillers are described. The issues of compatibility and toughening of PA blend nanocomposites are discussed, and current challenges are highlighted.

In this work, thermosetting resin, epoxy and fibre loading were used in optimizing the strength at which ABS/epoxy coated kenaf fibre (EKF) composites would perform apparently during mechan- ical stress. Kenaf bast fibres were resin coated before incorporated into engineering thermoplas- tic ABS at its processing temperature (230˚C), cured in-situ at internal mixer and later compres- sion moulded at 210˚C under 65 kg/cm2 pressure. The results showed the optimum level of tensile strength with thermoset and fibre loading as well as increase in strong interfacial bonding while the hardness values increased with increasing thermosetting and fibre contents. Both the tensile and flexural modulus apparently increased as the fibre contents increased.

In this research, polycarbonate (PC) composites with short glass fiber (SGF) and short carbon fiber (SCF) hybrid fiber reinforcements were compounded by single screw extruder and specimens were prepared by injection molding machine. This article aims to investigate the mechanical properties of PC hybrid composites, by means of the experimental and the theoretical methods. The composites were subjected to tensile test. Experimental results showed the improvements in tensile strength and modulus by increasing the SCF content of the hybrid composite. The theoretical tensile strength was predicted based on Kelly–Tyson model and rule of hybrid mixture. Kelly–Tyson model showed to be a good approximation to predict the tensile strength of composite. When the SCF was replaced by milled carbon fiber (MCF) to form a PC/SGF/MCF hybrid system, poorer mechanical properties are reported due to the weaker interfacial adhesion between MCF and PC, as proven by the scanning electron microscopy. POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers

The interfacial and mechanical properties of nonwoven kenaf fibre (KF) reinforced acrylic based polyester composites fabricated by resin impregnation process were studied. Different types of treatments were applied to KF, i.e. alkali treatment with NaOH at concentration of 6% (at room and elevated temperature of 60°C) and heat treatment at 140°C for 10h. FT-IR spectral data showed the chemical changes in KF that induced the modification of physical and interfacial characteristics of KF. Alkali treated KF was found to have smaller diameter but higher density. Significant increase in the crystallinity index of treated KF contributed to the improved fibre strength. AFM analysis revealed the exposure of cellulose micro-fibril network and the increase in the area peak density value of treated KF. Surface energy of KF and surface tension of acrylic resin were obtained through Owens–Wendt–Rabel–Kaelble (OWRK) equation and Du Nouy ring approach, respectively, for the interfacial properties determination. The improved wettability of alkali treated KF was confirmed as higher surface energy of the fibre was recorded exceeding the surface tension of acrylic resin, thereby imparting better flexural properties and dynamic mechanical behavior, but conversely deteriorating the fracture toughness of the reinforced composites. POLYM. COMPOS., 2017. © 2017 Society of Plastics Engineers

In the pursuit of green and more sustainable product, natural fibre reinforced composites originating from renewable resources has gained interest in recent years. These natural fibres exhibit good mechanical properties, low production costs, and good environmental properties. However, one of the disadvantages of natural fibre reinforced composites is their high flammability that limits their application in many fields. Within this research, the effect of sodium silicate on the flammability and thermal properties of flax reinforced acrylic based polyester composites has been investigated. Sodium silicate is applied as binder and flame retardant system in impregnation process of the natural flax fiber mats. The addition of sodium silicate significantly improved the flame retardant efficiency but reduced the degree of crosslinking of the composites.

The present work studies the dependence of mechanical properties of kenaf fibre (KF) reinforced acrylic based polyester composites on the processing parameters. Prior to moulding, non-woven kenaf fibre (NWKF) with areal density of 1200 g/m2 was impregnated by acrylic based polyester resin using an impregnation line followed by a post-drying step. The flexural properties of the composites were investigated with respect to changes in impregnation and moulding conditions based on Design of Experiment (DOE) of Response Surface Methodology (RSM). RSM through Central Composite Design (CCD) was applied to develop a model of flexural properties with respect to the combination of processing variables. The mathematical regression models of the flexural properties were derived from the analysis of variance (ANOVA) to determine the model significance. All processing variables in linear terms exhibit significant effect on the flexural strength of the composites. Optimisation of the independent variables to maximise the flexural properties was estimated and verified.The present work studies the dependence of mechanical properties of kenaf fibre (KF) reinforced acrylic based polyester composites on the processing parameters. Prior to moulding, non-woven kenaf fibre (NWKF) with areal density of 1200 g/m2 was impregnated by acrylic based polyester resin using an impregnation line followed by a post-drying step. The flexural properties of the composites were investigated with respect to changes in impregnation and moulding conditions based on Design of Experiment (DOE) of Response Surface Methodology (RSM). RSM through Central Composite Design (CCD) was applied to develop a model of flexural properties with respect to the combination of processing variables. The mathematical regression models of the flexural properties were derived from the analysis of variance (ANOVA) to determine the model significance. All processing variables in linear terms exhibit significant effect on the flexural strength of the composites. Optimisation of the independent variables to maximise th...

The dental composites based on poly(methyl methacrylate)/hydroxyapatite (PMMA/HA) were prepared through heat-processing polymer powder-liquid method, in the presence of poly(lactic acid) powder (PLA; 5–20 phr). The PLA powder enhanced the flexural modulus and strength of PMMA/HA composites. The Alamar Blue assay results indicated the PMMA/HA/PLA composites were able to sustain human gingival fibroblasts (HGF) cells growth. The images of live/dead cells confocal showed the populations of living cells on the composites surface were confluent and the survival of HGF cells on the PMMA composites surface are assured. These features suggested that the PLA powder reinforced PMMA/HA composites demonstrated excellent biocompatibility.

Poly(lactic acid)/halloysite nanoclay composites (PLA/HNC) containing maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) were produced using melt compounding followed by compression molding. The effects of hygrothermal aging on the thermal properties and functional groups changes of the HNC reinforced PLA (with and without SEBS-g-MAH) at three different temperatures (i.e., 30, 40 and 50 °C) were analyzed using differential scanning calorimetry and Fourier transform infrared spectroscopy techniques. The diffusion coefficient (D) of PLA was decreased by the incorporation of HNC and SEBS-g-MAH. The activation energy of water diffusion (E a ) of PLA/HNC/SEBS-g-MAH nanocomposites was higher than that of pure PLA. The glass transition temperature (T g ), cold-crystallization temperature (T cc ) and melting temperature (T m ) of the PLA sample were shifted to lower temperature and the effect was more pronounced at 50 °C. The carbonyl index values of all PLA samples increased after immersed in 40 and 50 °C, which is due to the formation of higher amount of carboxyl groups during the hydrolysis process.

Injection-molded poly(lactic acid)/organo-montmorillonite (PLA/OMMT) and poly(lactic acid)/ nano-precipitated calcium carbonate (PLA/NPCC) were exposed to a water absorption test at 30°C for 70 day...

Application of the available natural resources became crucial for developing sustainability recently. The use of natural fiber as reinforced materials in polymer composite materials is gaining new interest from within industry. In this research, the effect of different fiber loadings and different types of kenaf yarns, used on the properties of Pultruded Kenaf Fiber Reinforced Composites (PKFRC), was studied. The pultruded composite samples were prepared with different fiber loadings and sizes (tex) of kenaf fiber. Three different fiber loadings, i.e., 60, 65, and 70% were used during the preparation of the PKFRC samples. Flexural and compression testing was performed, to study the effect of different fiber loadings and different kenaf fiber yarns, on the mechanical properties of kenaf fiber pultruded composites. The results show that the highest fiber loading of 70% gave more desirable flexural and compression properties to the PKFRC. The use of twist kenaf yarn fiber showed lower mechanical properties of PKFRC as compared to the single kenaf yarn. Damage configurations and accumulations for each loading case were examined. A morphological study, using optical microscopy (OM) revealed the type of fracture that occurred in the pultruded samples after mechanical testing. POLYM. COMPOS., 36:1224–1229, 2015. © 2014 Society of Plastics Engineers

Poly(lactic acid)/halloysite nanoclay composites (PLA/HNC) containing maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) were exposed to hygrothermal aging at three different temperatures, i.e., 30, 40 and 50°C. The analysis was focused on the water diffusion kinetics and physical changes induced by the hygrothermal degradation. The water absorption kinetics of the PLA/HNC composites at immersion temperature of 30 and 40°C conforms to Fick's law. The equilibrium water absorption (Mm ) and diffusion coefficient (D) values are dependent on the SEBS-g-MAH content and immersion temperatures. Hydrolytic chain scission provoked significant molecular weight reduction. Nevertheless, adding SEBS-g-MAH improved hygrothermal stability of the PLA/HNC nanocomposites.

Biodegradable poly(butylene succinate)/organo-montmorillonite nanocomposites were prepared at different organo-montmorillonite loadings, using maleic anhydride-grafted poly(butylene succinate) as compatibilizer. Poly(butylene succinate) nanocomposites were exposed to outdoor natural weathering for 180 days. Weight loss and decrease in mechanical properties after weathering revealed the degradation of poly(butylene succinate). Natural weathering caused photo-oxidation on poly(butylene succinate), leading to the formation of degraded products, as manifested in Fourier transform infrared spectroscopy. Gel permeation chromatography showed a significant reduction in molecular weight after weathering. It was noted that poly(butylene succinate) nanocomposite exhibited lower degradability as compared to neat poly(butylene succinate), due to the enhanced barrier properties after the addition of organo-montmorillonite. However, the incorporation of maleic anhydride-grafted poly(butylene succinate) increased the degradability. Degree of crystallinity of poly(butylene succinate) reduced after weathering, as shown in differential scanning calorimetry. Scanning electron microscopy analysis revealed fungal and bacterial colonization on the sample surface. In addition, the isolation and identification of bacterial strain were also performed.

Multiwalled carbon nanotubes (MWCNTs) based on bimetallic Co-Mo/MgO catalyst were produced in large scale by catalytic chemical vapor deposition method (CCVD) of methane. X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Raman spectroscopy proved carbon nanotube (CNT) forma- tion. As-produced multiwalled carbon nanotubes (PCNTs) and commercial ones (CCNTs) with the same diameter (10- 20 nm) were melt blended with polyamide 6 (PA6). XRD patterns of nanocomposites showed applying 0.1% of both types of CNTs changed the crystalline structure of neat PA6 from !/" form to thermodynamically more stable !-phase structure. Differential scanning calorimetry (DSC) showed both types of CNTs shifted crystallization temperature of about 10-15°C to higher temperature due to the nucleating effect of nanotubes. Furthermore, degree of crystallinity increased by about 30% in some composites, especially for PCNTs. Nanocomposites containing PCNTs exhibited improvements in thermal decom- position temperature in comparison with CCNT nanocomposites. Nanocomposites melt viscosity increased at high CNTs loading due to the filler-matrix entanglements.

Polylactic acid (PLA)/kenaf bast fiber (KF) composites were prepared with different amounts (0 to 40 wt%) of ethylene acrylate copolymer impact modifier (IM). With increasing IM content, the impact strength and elongation at break of the composites improved but an opposite trend was observed for the tensile strength and modulus. Addition of IM resulted in the formation of ductile or flexible interface between the PLA matrix and KF as confirmed by scanning electron microscopy examination on the composite fractured surfaces. Deformability of the PLA matrix was also improved. Mechanisms for the morphology-property relationships of the composites were discussed.

Poly(lactic acid) (PLA)/halloysite composites were prepared using melt compounding followed by compression molding. Maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) was used to toughen the PLA composites. The mechanical properties of the PLA composites were studied through tensile, flexural, and impact tests. The thermal properties were characterized by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The fracture surfaces of the composites were assessed by using field emission scanning electron microscopy (FESEM). The impact strength and thermal properties of the PLA/halloysite composites were increased by addition of SEBS-g-MAH.