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Pineapple leaves (PALs) are useful agro wastes which have the potentials to be used as an alternative source of non-wood natural fiber. In this study, different extraction methods had been investigated to identify the most feasible pineapple leaf fiber (PALF) extraction method, based on the dry pulp yield and the PALF morphology. The manual retting using a ceramic scrapper led to low yield of around 1.8 % (wt.), while water retting for 21 d led to about 6.0 % (wt.) yield of dark greenish dry pulp. Both methods resulted in PALFs which still contained with non-cellulosic residues, as verified by scanning electron microscopic (SEM) imaging. The chemical extraction of PALF using various NaOH solution concentrations (i.e. 1 to 20 % (wt.)) gave different yields. Based on the SEM images, clean and smooth surfaces of fibrils were observed when the NaOH solution concentrations applied at or higher than 6 % (wt.), implying that all impurities including lignin and wax had been completely removed. The mechanical-chemical extraction method produced significantly more dry pulp compared to the chemical extraction method at the same NaOH solution concentration. This is attributed to the fact that the crushed PAL has a larger surface area, thus providing more reaction possibilities with NaOH solution. Finally, it was found that the crushed PAL that cooked at 90 °C needed at least 90 min of cooking time to obtain satisfying whitish dry pulp.

Low density polyethylene / tapioca starch (LDPE/TS) blends have respectable biodegradation properties and poor mechanical and thermal properties compared to neat LDPE film. The focal target of this study is to investigate the effect of calcium carbonate (CaCO3) loading on mechanical, thermal, and biodegradation properties of LDPE/TS film. LDPE/TS/CaCO3 blend films were prepared using film blown processing. The results indicated that the maximum loading of CaCO3 which feasible to be incorporated into (45:20) LDPE/TS blend is 10% without exertions during film processing. CaCO3 has remarkable effect on mechanical properties of LDPE/TS films in both machine direction (MD) and cross direction (CD). Water absorption capacities of the films were reduced after the addition of CaCO3. Differential scanning analysis shows that more amorphous regions were generated in the blend structure after the addition of CaCO3 into the blend. Scanning Electron Microscope (SEM) analysis indicated a significant distribution of starch and CaCO3 particle in LDPE matrix, wherever the size of starch particles seems to be bigger than the size of CaCO3 particle.

This paper reports on an investigation of the effects of calcination on the structure and dielectric properties of polyethylene/silica (SiO 2 ) nanocomposites. Calcination temperatures of 600 and 900 °C have been used in order to modify the surface chemistry and surface structure of the SiO 2 . The results show that, after calcination, the concentration of surface hydroxyl groups and water molecules around SiO 2 and within resulting nanocomposites is reduced. The real permittivity of nanocomposites containing calcined SiO 2 decreases compared to nanocomposites based on uncalcined SiO 2 . The DC breakdown strength of nanocomposites containing calcined SiO 2 becomes higher than those containing uncalcined SiO 2 . In contrast, AC breakdown was found not to be significantly affected by addition of any of the silicas considered here. The use of calcined nanofillers can have positive effects akin to the use of chemically functionalized nanofillers in enhancing the dielectric properties of nanocomposites; both approaches remove polar surface hydroxyl groups.

The present study reports the preparation and characterization of kenaf papers that reinforced with tapioca starch by using the ammonium zirconium (IV) carbonate as coupling agent. The examination shows the tearing resistance, tensile strength, and Young’s modulus of the kenaf papers are enhanced with the addition of starch and coupling agent, up to 3% and 1%, respectively. Under the optimum formulation, the degree of coupling reaction is 87%. The Fourier transform infrared and morphological analyses confirm the performance enhancement of kenaf papers is achieved via the formation of chemical bonding between the kenaf fiber and tapioca starch.

The present work reports the influence of crosslink chemicals (vinyltrimethoxylsilane, dicumyl peroxide, and dibutyl dilaurate) on the mechanical strength and water absorption of the rice straw/high density polyethylene bio-composites. As revealed by the Fourier transform infrared spectra, the surface interaction between the fibers and polymer was improved through the use of vinyltrimethoxylsilane (coupling agent). By properly regulating the dicumyl peroxide (radical initiator) and dibutyl dilaurate (catalyst), the surface interaction was further enhanced, and thus the tensile and flexural strength. These observations were validated by the reduction in the water absorption of the bio-composites as well as the fracture surface examination.

A review on the change mechanism of conjugated polymer upon radiation exposure is presented. The change mechanism is mainly focused on the polymer's optical properties instead of its electrical properties. This research explores the effect of ionizing radiation on the optical change of conjugated polymer. This study also reviewed the possibility of using conjugated polymer as a radiation sensor vis-a-vis radiation type and the optical response. From material point of view, topochemical reaction, conjugation length and the degree of anisotropy of the conjugated polymer itself were identified as factors affecting the polymer's optical properties. These factors are tunable to meet a required optical degree, thus making the observation using the optical properties of a conjugated polymer possible for a radiation sensing tool. Based on the review, alteration of the factors and its mechanism of change occurs at macromolecular level. Therefore, a material at its smallest size down to a single molecule could be possible for the indication of radiation. Thus, radiation sensor made of nano or micro colloidal conjugated polymer deserves attention for future development. Copyright © 2017 John Wiley & Sons, Ltd.

Cellulosic natural fibres from pineapple leaves are considered as a green alternative to the conventional polyethylene (PE) soil cover in agro-industry. The use of pineapple leaf fibres (PALFs) soil cover can overcome the disposal problem of the conventional plastic covers which take hundreds of years to degrade. This research was undertaken to study the effectiveness methods of extracting the PALFs. The mechanical method utilized ‘roller and bladder system’, where the chemical method involved the extraction with 6% NaOH, 20% aqueous acetone, and pineapple juice solution. The semi-mechanical method was a combination of “roller and bladder” system and a chemical retting process using 6% NaOH alkaline solutions. The characteristics of the extracted fibers were determined using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Kappa number test of the fibres extracted with semi-mechanical method showed the lowest percentage of lignin (3.39%). Based on XRD results, the highest percentage of crystallinity was recorded when PALF was extracted using the semi-mechanical method. A remarkable change on the morphological surface the biodegraded PALF soil cover was observed after 90 days of soil burial test. Biodegradability of soil cover made from PALF was higher than the commercial degradable soil cover i.e. PE/starch (80 wt% PE/ 20 wt% starch). Meanwhile, the growing rate and the soil fertility of chili tree that used PALFs soil cover showed better results than the chili tree that used conventional PE/starch soil cover.

For last decades, the topic of polymer nanocomposites have been widely studied in the scientific literature since the material system promises a substantial dielectric properties enhancement even at low nanoparticles loading. Nevertheless, factors contributing to increased or decreased DC breakdown strength of nanocomposites are far from understood. In this paper, an investigation on the DC breakdown strength of polyethylene nanocomposites that contained different amounts of silicon nitride with different non-isothermal crystallization processes is reported. The non-isothermal crystallization techniques were determined by fast, medium and slow cooling rate conditions by the differential scanning calorimetry (DSC) for all the nanocomposite samples. The chemical structures of the nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy and the morphology of the nanocomposites was determined by scanning electron microscopy (SEM). From DC breakdown testing, the breakdown results of the nanocomposites were found to vary under different non-isothermal crystallization conditions.

Polymer nanocomposites have become one of the main research studies in investigating the potential use of new dielectric materials especially in high voltage insulation. Many promising results, especially on the use of polyethylene nanocomposites as dielectric materials, have been reported in the literature. Significantly, the main factor that affects the dielectric performance of the materials was attributed to the interface between the host matrix and the nanofiller. This paper reports on an investigation into the AC and DC breakdown performance of unfilled and polyethylene nanocomposites containing silicon dioxide (SiO2) nanofillers at different loading levels (1 wt%, 4 wt%, and 8wt%). By using the Fourier transform infrared (FTIR) spectroscopy, the chemical structures of the materials were characterized. The dielectric permittivity of the samples was analyzed using dielectric spectroscopy. From the breakdown results, it showed that AC breakdown testing did not result in significant changes on the breakdown strength between uncalcined and calcined nanofillers. Meanwhile, for DC breakdown testing, introducing a small number of nanofillers could have a major impact on the DC breakdown strength. These results were correlated with the calcination process of nanofiller; the DC breakdown strength improved for calcined nanofiller compared to uncalcined nanofiller.

Polymer nanocomposites has a huge potential to serve as dielectric materials. These materials were found to have a great capability in withstanding high voltage levels. In nanocomposites development, the breakdown strength of the materials was often reported to be higher, lower or similar, in comparison with the unfilled polymer. Because of this, the breakdown performance of nanocomposites is said to be dependent not only on the polymer/nanofiller combination, but also on the sample preparation techniques. Unfortunately, factors leading to increased or decreased the breakdown strength of nanocomposites are less understood. In this paper, investigation into polyethylene blend systems that contain different amounts of silicon nitrite nanofiller with different non-isothermal crystallization processes was reported. The non-isothermal crystallization techniques were determined by fast, medium and slow cooling rate conditions while preparing the samples. Differential scanning calorimetry (DSC) was used to characterize the thermal behavior of the polymer nanocomposites. The AC breakdown data showed that the use of different non-isothermal crystallization techniques affected the AC breakdown strength of each material type.

Polypropylene has been widely used in high voltage insulation. This material has recently been regarded as to potentially compensate conventional limitations of XLPE such as being difficult to recycle and having significant space charge accumulation and poor thermal conductivity. Currently, there are various types of polypropylene produced in the market. Therefore, this research attempts to investigate the breakdown performance of several types of polypropylene, namely, polypropylene homopolymer, polypropylene impact copolymer, and the combination of both in 50:50 ratio. The thermal behaviors of the samples were characterized using scanning calorimetry (DSC). The thermal characterization demonstrates that all types of polypropylene have a similar melting temperature of about 162 °C. Besides that, the breakdown test reveals that polypropylene homopolymer has the highest DC breakdown of 278 kV/mm. Meanwhile, polypropylene impact copolymer has the lowest breakdown strength of 109 kV/mm and 239 kV/mm under the applied AC and DC fields, respectively.

The main objective of this article is to investigate the potential of using pineapple leaves as non-wood materials for paper production. The chemical compositions of non-wood raw materials and the advantages and disadvantages of different pulping methods were reviewed. The advantages of solvent pulping process over other techniques in terms of scale production, water, energy and chemicals consumption, and pulp quality might be the driving forces of using this process in future production of pulps from pineapple leaves waste. Pineapple leaves are cellulosic, abundance agro-waste of pineapple industries with chemical composition of high cellulose contents. Good mechanical properties, renewable resource, and low cost fibers are the main factors that lead to high potential of pineapple leaves’ fibers to be used as alternative raw materials in paper industries.

Pineapple has been known for a number of beneficial biological activities such as anti-oxidative and anti-browning. Some of these bioactivities are contributed by enzymatic complex in pineapple and it can be found mainly in the skin extracted pineapple juice. The purpose of this study is to determine the effect of the pineapple juice as a pulping and bleaching agent in the process of papermaking. During pulping of pineapple leaf fibre, the mixture of pineapple juice/water was added together with a constant amount of 3% Sodium Hydroxide (NaOH) at various concentration of pineapple juice (0%, 20%, 40%, 60% and 80%). Pineapple leaf fibre (PALF) was soaked several times with pineapple juice and NaOH during pulping and bleaching process in order to get the optimum results of the paper sheet obtained. The mechanical and physical properties of paper sheet were studied by measuring its tensile strength, tear resistance and water absorption. Comparatively, paper sheet produced from NaOH pulping shows better mechanical and physical properties than the mixture pulping of NaOH and pineapple juice. Additionally, pulping with higher concentration of pineapple juice tends to give long fibre rather than short fibre. Overall, the results of this study can be used as an alternative way in the production of paper and it also opens a door to utilize wisely the waste residue of pineapple in other sectors.

Spent coffee grounds that are left behind during the coffee brewing process consist of valuable tannin compounds which makes them ideal material as a renewable tannin resource. For this reason, the concept of cleaner production had been applied in practice and a tannin extraction process with spent coffee grounds as raw material was investigated in the present study. Among the extraction key factors, namely sodium hydroxide concentration, extraction temperature, liquid to solid ratio, and extraction time, the former three factors had exerted a considerable effect on spent coffee ground tannin extraction yield and its reactivity. However, extraction time had only marginal effects which could be simply neglected in the tannin extraction process. These observations imply that spent coffee grounds can be reused as a renewable tannin resource by properly selecting the extraction parameters in order to produce the spent coffee ground tannin with desirable extraction yield and reactivity. By taking both the spent coffee ground tannin extraction yield and reactivity into consideration, the optimum extraction conditions are; 5% sodium hydroxide concentration, 100 °C extraction temperature, 30 min extraction time, and 8.23 liquid to solid ratio, so that tannin with a high extraction yield (21.02%) and high reactivity (29.69%) could be recovered. The present study provides an understanding on the impact of the extraction parameters on isolated spent coffee ground tannin as well as to fill up academic deficiencies in spent coffee grounds, which, in turn, could serve as a reliable guideline for the development of a full-scale, sustainable spent coffee ground tannin extraction process in coffee industries.

In this study, carbon-13 nuclear magnetic resonance in the solid state using cross-polarization and magic angle spinning (CP-MAS 13C NMR) spectroscopic and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometric methods were applied to characterize the composition, constituent monomer and oligomeric structure of tannins of spent coffee grounds (SCG). The findings elucidated that the monomeric constituents of tannins of SCG primarily composed of catechin, gallocatechin, chebulic acid, gallocatechin-3-O-gallate and accompanied by minor amount of fisetinidin concurrently. Appreciable amount of catechin was found among the observed components. Hence, this simply implied that catechin was the main substructure of the tannins of SCG. It is expected that the present findings will serve as a platform towards a structural understanding of tannins of SCG in filling up the gaps in the field of study of SCG, and simultaneously promoting the use of SCG as a renewable resource for tannins.

In this study, a series of tapioca starch-based low density polyethylene (LDPE) biofilms were prepared via extrusion process and further using blown film extrusion with various contents of starch. Various contents of glycerol and palm oil based olein as plasticizers, both ranging from 5 wt% to 20 wt% were added to blends. The starch-based LDPE blends were undergo the melt flow index analysis to study its processability before further process by film blowing extrusion. Both film blowing ability and melt indexes displayed the effect of both plasticizers in starch-based LDPE blends. Starch based LDPE biofilms with addition of 5 wt% palm oil based glycerin show large influence on the shear viscous properties of starch polymer melts compared to glycerol. Palm oil based glycerin would decrease the viscosity of starch polymer melt since it can decrease the polymer entanglement density and increase the ease of disentanglement.

In electrical insulation, polymer nanocomposites become one of the main research areas for exploring the potential of insulating materials in terms of dielectric strength enhancement. This is due to many promising results of nanocomposites reported by the dielectrics community. For this, the interfaces between the filler and base polymer is one of the major factors for improving the filler/ polymer interaction within the nanocomposites. This paper reports on an investigation into the AC breakdown performance of unfilled and nanofilled polyethylene. With different nanofillers (silicone dioxide (SiO 2 ) and zirconium oxide (ZrO 2 )) and different loading levels (1 wt%, 4 wt%, 8 wt%). The thermal behavior of the materials was characterized using differential scanning calorimetry (DSC) and the melting traces for the materials were determined. The breakdown results showed that a low nanofiller loading level (1 wt%) did not significantly affect the breakdown strength compared to the unfilled sample. When comparing samples containing SiO 2 and ZrO 2 nanofillers, it appeared that those with ZrO 2 filler had slightly higher breakdown strength compared to those containing SiO 2 nanofiller. The significance of the results is discussed.

Increasing demands in high voltage applications result in the need to design new electrical insulation systems. For this reason, polymer nanocomposites have recently been actively studied. In the dielectrics community, polymer nanocomposites refer to polymer matrices incorporating nanometer-sized fillers as a means for enhancing the dielectric properties. These materials were found to have a great capability in withstanding high voltage levels such as those required in high voltage alternating current (HVAC) and high voltage direct current (HVDC) applications. This paper reports on an investigation into polyethylene systems that contains different amounts of nanosilica with different non-isothermal crystallization processes. The non-isothermal crystallization techniques were determined by fast, medium and slow cooling rate conditions while preparing the samples. The thermal behavior of the polymer nanocomposites was characterized by differential scanning calorimetry. The breakdown results showed that the use of different non-isothermal crystallization techniques affected the breakdown strength of the same material type.

Polymer foam biocomposites based on polypropylene/rice straw (PP/RS) were successfully prepared by using an extrusion foaming process. The compounding of PP and RS was performed in a twin-screw extruder which was blended with crosslinker; dicumyl peroxide (DCP) and blowing agent; azodicarbonamide (AZ). The foam biocomposite was extruded at temperatures of 180, 190, 190 and 200 °C respectively, which set from the feeder until the die zone. The thermal properties were investigated by using differential scanning calorimetry (DSC).

Normal 0 false false false EN-MY X-NONE X-NONE MicrosoftInternetExplorer4 The LDPE was blended with various contents of tapioca starch (10%, 20%, 30%, and 40%) with addition of compatibilizer, which is PE-g-MA and cooking oil as plasticizer. The blends were prepared by co-rotating twin screw extrusion process and characterized by melt flow index (MFI) analysis and tensile test. Tapioca starch based polyethylene biofilms were studied in term of biodegradability by fungi test. The increasing of starch content to LDPE blend was reduced the MFI values and tensile strength but in 30% and 40% of starch content in tensile strength is higher than control LDPE’s strength due to molecular orientation in sample. However, incorporation of PE-g-MA as compatibiliz increase the mechanical properties of starch based polyethylene blends due to the reaction between maleated PE and starch, thus improves adhesion and reduces slippage at matrix-filler interface.ers The increasing of TS also increase the water content in film sample, weight loss percentage in TGA, and percentage degradation of LDPE/TS blend film. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

This paper provides an insight into the potential of utilising sago pith waste (SPW) to produce composite material. SPW is a fibrous waste that is produced as a result of the sago starch extraction process. It is made up of more than 60 % in weight of sago starch and was successfully converted into natural fibre reinforced thermoplastic starch composite using twin screw extrusion in the presence of different quantities of glycerol and water as plasticisers. No binder was added throughout the process. Good fibre-matrix compatibility was proven by SEM. Due to phase separation and fibre agglomeration, tensile strength of the composite decreased with increasing glycerol content while elongation at break remained unchanged at low values. Activation energies, Ea of the composites were computed from thermogravimetric analysis (TGA) data using Broido and Coat-Redfern equations. The obtained Ea values indicated that plasticisation led to the reduction in thermal resistance of SPW. It is suggested that blending the plasticised SPW with sago starch and polyvinyl alcohol will greatly improve upon the existing shortcomings, potentially resulting in useful consumer products from SPW, an unutilised, water polluting waste.

Active and smart packaging is a promising form of food packaging that offers a great economical potential due to consumer demand for a packaging that accommodate a hectic way of life. An antimicrobial film with pH colour indicator (pHF) can be made by incorporating suitable antimicrobial (AM) agent and colour indicator into food package matrices whilst applying a bio switch concept to inhibit the pathogenic microorganisms and respond automatically to changes (external stimuli) in the environment. The present work aimed to study the developed formulation of hydroxyethylcellulose (HEC)/wheat-starch based pHF film in which the active compound, thymol (0.5, 1, 1.5, 2, and 2.5% w/w) and 50:50% w/w bromothymol blue and methyl red (as the colour indicator) against microbial growth. A solution casting method was used in the film preparation while thymol and colourant were incorporated prior to casting. The effect of thymol showed a range of microbial inhibition zones of 16.3 - 26.4% and 22.1 - 39.9% towards E. coli and B. subtilis, respectively. Whilst, a lower inhibition zone of 0.4 - 5.1% was demonstrated for fungus A. niger.

The main objective of this study is to evaluate the effect of rice starch and polyvinyl acetate (PVAc) as binding agents on mechanical, thermal and water absorption properties of molded rice bran/rice straw (RB/RS). Rice bran (RB) and rice straw (RS) were molded in form of paper sheet using compression-molding technique. Tearing resistance of RB/RS was enhanced by 135%–140% after the addition of PVA and rice starch binders. Thermal stability of RB/RS was affected positively by PVAc and negatively by rice starch binders. Fractured surface analysis of inverted optical microscope indicated that RB/RS samples have clear visible phase separation without binding agent compared to RB/RS with binders of PVAc and rice starch.

This article reports improved mechanical properties of epoxy/polyaniline nanowires nanocomposite (EP/PANI) by using para-hydroxybenzene sulfonic acid as the dopant. The PANI nanowires show no chain dedoping in the EP. Mechanical properties of the nanocomposites were maintained while achieving its conductive state and revealed pull-out of bundles rather than individual nanowire.

Novel conducting kenaf core/polyaniline (KC-PANI) biofibers were successfully prepared via in situ oxidative polymerization. The newly developed conducting KC achieved enhancement in DC conductivity up to seven fold compared to the raw KC. Enhanced interaction was obtained between the acetylated KC-PANI surfaces compared to untreated KC-PANI, without significant loss in the cellulose crystallinity. The morphological analysis revealed uniform layers of PANI deposited on the surface of acetylated KC. Epoxy resin (EP) containing KC-PANI (EP/KC-PANI composites) showed that the electrical percolation of KC-PANI occurred at 20 wt.%. The tensile strength of the EP/KC-PANI composites was slightly reduced compared to that of EP/KC composites at the same loading fraction. However, the flexural test revealed that the presence of KC-PANI increased the flexural strength of the EP composites by up to 15 wt.% loading. Electron micrograph of the EP/KC-PANI composite indicated favourable adhesion between components.

This article reports the preparation and characterization of newly developed hybrid composites consisting of epoxy resin (EP) matrix, acetylated kenaf bast fiber (AKF) and conducting polyaniline (PANI) nanowires. Initially, the EP/AKF composites were prepared by varying the AKF loading (5–30 wt%). The EP/AKF displayed an optimum tensile strength at 20 wt% AKF loading which was higher than that of untreated kenaf fiber EP composites (EP/UKF). The hybrid composites of EP/AKF/PANI were then prepared by using 20 wt% AKF loading with PANI inclusions from 2 to 14 wt%. The addition of PANI into EP/AKF induced positive electrical properties without considerably sacrificing its mechanical integrity. It was found that the electrical percolation threshold of these hybrid composites was at 11 wt% of PANI loading. PANI inclusions at above the percolation loading resulted in reduction of tensile and flexural strength. Meanwhile, no significant mechanical loss was observed below the threshold. The fracture morphological analysis revealed the occurrences of PANI nanowires pull out from the matrix. The Fourier transform infrared spectroscopy showed that the PANI component still maintained its doped condition inside the EP/20AKF. Water absorption and thermal analysis indicate that the PANI incorporation induced lower water uptakes and greater thermal stability to the EP/20AKF, respectively.

Sago pith waste (SPW), a fibrous residue resulted from the sago starch extraction process, was characterised in terms of moisture content (82%) and starch content (62%, dry weight basis). The dried and ground SPW was irregular in shape and has a CE diameter of 29.41 μm, similar to that of pure sago starch (28.43 μm). SEM micrograph showed that SPW is a mixture which consists of sago starch and fibre, verified by FTIR spectrum and XRD diffractogram observed from peaks which were attributed to sago starch and SPW fibre. With glycerol and water as plasticisers, SPW was then plasticised successfully to form a natural fibre filled thermoplastic starch composite using a twin screw extruder in the presence of various quantities of glycerol. No synthetic polymer binder was added. Plasticisation led to the disruption of the original C-type crystallinity of sago starch. However, V H and B type crystallinities were developed after processing as a result of the reorganisation of amylose, amylose–lipid complex (very fast) and amylopectin chains (slow).

Conducting kenaf/polyaniline (KF/PANI) biofibers were successfully prepared via in situ oxidative polymerization. It was demonstrated, for the first time, the possibility of imparting new electronic properties on KF by coating with acid-doped PANI. The morphological analysis revealed three different PANI morphologies on the KF, depending on the type of acid doping. Enhanced interaction was achieved between the fiber-PANI surfaces, mainly from the π − π interactions. The newly developed conducting biofibers achieved enhancement in DC conductivity up to fivefold compared to the unmodified KF. Mechanical test on the conducting biofibers revealed no significant loss in the tensile properties.

Response surface methodology was used to simultaneously optimize the electrical and mechanical properties of newly developed conducting biofibers made up of kenaf fiber/polyaniline (KF/PANI). The effect of process parameters such as PANI amount (1–10 wt.%), dopant concentration (5–25 N), and molar ratio of aniline/oxidant solutions (0.5–1.5) were studied using Design of Experiment. Both of the responses (electrical conductivity and unit break) obtained a quadratic model. The experimental values were in good agreement compared to the optimized process. The scanning electron microscope images of the optimized sample revealed uniform PANI component on the KF with nanofibrillar features.

Newly modified biofibers made up of kenaf fibers (KF) and conducting polyaniline (PANI) were successfully prepared via in situ polymerization. Several characterization methods were done to elucidate the interaction between the KF surfaces and the in situ polymerized PANI. The PANI coated KF (KF/PANI) achieved new electronic properties, without sacrificing its mechanical properties and natural fiber characteristic. Initial mercerization on the KF yielded better PANI coated fibers compared to the untreated KF. Fiber bundle tensile test on the untreated KF/PANI revealed a drop in the unit break of about 48% compared to the untreated neat KF. Meanwhile, the mercerized KF/PANI showed reduction of about 17% compared to the uncoated mercerized KF. The mercerized KF/PANI exhibits polaronic transitions, existence of favorable IR peaks and Raman scattering, enhanced DC conductivity, and better morphological characteristic as a result of the in situ PANI coating. Such electronically modified natural fibers could be ...

The specific heats (Csp) of neat and glycerol-plasticized poly(vinyl alcohol) (PVOH) were studied by differential scanning calorimetry at 330530 K. Glycerol-plasticized poly(vinyl alcohol) was prepared by a melt-blending method. The outcomes were modeled into mathematical functions. Incorporation of glycerol increased the specific heat of PVOH. Glycerol provided internal lubrication to the PVOH system, giving a smoother and lower-amplitude melting curve. As a result, glycerol-plasticized PVOH had a lower melting-temperature range than neat PVOH. However, higher energy was required to increase the temperature of glycerol-plasticized PVOH. The modeling functions showed a best fits regression range of 0.9670.999. Neat PVOH and glycerol-plasticized PVOH required 1166.05 J/g and 2113.09 J/g, respectively, to increase the temperature from 330 to 530 K. J. VINYL ADDIT. TECHNOL., 18:198203, 2012. (c) 2012 Society of Plastics Engineers

In this article a modified polydimethylsiloxane (PDMS) blended polystyrene (PS) interpenetrating polymer network (IPN) membranes supported by Teflon (polytetrafluoroethylene) ultrafiltration membrane were prepared for the separation of ethanol in water by pervaporation application. The relationship between the surface characteristics of the surface-modified PDMS membranes and their permselectivity for aqueous ethanol solutions by pervaporation are discussed. The IPN supported membranes were prepared by sequential IPN technique. The IPN supported membrane were tested for the separation performance on 10 wt % ethanol in water and were characterized by evaluating their mechanical properties, swelling behavior, density, and degree of crosslinking. The results indicated that separation performance, mechanical properties, density, and the percentage of swelling of IPN membranes were influenced by degree of crosslink density. Depending on the feed temperature, the supported membranes had separation factors between 2.03 and 6.00 and permeation rates between 81.66 and 144.03 g m-2 h-1. For the azeotropic water–ethanol mixture (10 wt % ethanol), the supported membrane had at 30°C a separation factor of 6.00 and a permeation rate of 85 g m-2 h-1. Compared to the PDMS supported membranes, the PDMS/PS IPN supported blend membrane ones had a higher selectivity but a somewhat lower permeability.

The effect of glycerol on the mechanical, thermal and water absorption properties of thermoplastic tapioca starch reinforced rice straw fiber grinded in the range below 100 µm was investigated. Compound formulation was done on twin screw extrusion and the extrudates were pelletized. The compounded samples were processed using compression moulding to form sheet at 150°C for tensile and thermal gravimetric. SEM studies were investigated on fracture surface of composites. Tensile test was done in accordance to ASTM D638. Thermal analysis was used to determine the degradation temperature of composite. Increasing the amount of glycerol increased the tensile strength of composite up to 30 phr of glycerol, however, increasing to 40 and 50 phr glycerol was decrease the strength but elongation at break of composites was increased with increasing glycerol content. Thermal Gravimetric Analysis (TGA) result showed that increased amount of glycerol content lead to decrease in degradation temperature of the composite and SEM micrograph showed that good dispersion and adhesion between rice straw fiber and starch.

A series of blends of sago pith waste (SPW) and poly(vinyl alcohol) (PVA) were prepared. Mechanical and water absorption properties of the composites have been investigated. In this study, variable amounts of plasticized SPW (pSPW) and PVA (pPVA) were processed in the presence of glycerol as plasticizers. Composites were compression molded and evaluated. The addition of pSPW reduced the tensile properties of the composites, lowering the elongation and increasing Young’s modulus. The reduction in mechanical strength with the addition of pSPW was a general phenomenon due to the poor interfacial adhesion between the pPVA and Pspw, which can be proved by the scanning electron microscope observations. The percentage of water absorbed of the pPVA/pSPW biocomposites was higher than either the pPVA or pSPW alone while pSPW showed better water resistance compared to pPVA because of the restricted mobility exerted by the cellulose fibers. The incorporation of SPW into PVA decreased both the mechanical and water absorption properties.

The weathering performance of rice husk-filled high-density polyethylene (RHPE) and natural wood was investigated in this study. The injection molded RHPE, in column end-cap (CECap) shapes, was exposed to both natural and accelerated weathering attacks. The durability of RHPE was compared to Kempas wood (Koompassia malaccensis) and neat polyethylene. Wood underwent the greatest losses in properties among the specimens. Four months of outdoor weathering turned the color of RHPE CECap into silvery grey. When the exposure time increased, the color of RHPE composite faded faster than neat polyethylene. The wood surface darkened and RHPE surface flaked off after being exposed to accelerated weathering conditions. Prolonged weathering exposure caused loss of impact strength of the RHPE composites. In general, RHPE is more resistible to weathering attacks as compared to Kempas wood.

Thermal behaviour and interactions of glycerol plasticized polyvinyl alcohol (PVOH)–cassava starch (CSS) blended films were analysed using thermogravimetry and differential scanning calorimetry methods. The outcomes showed that addition of glycerol has reduced the onset and end-point melting temperatures of the blended films. Samples with 30 and 40 wt.% of PVOH–glycerol blended with CSS exhibited experimental enthalpy of melting (ΔHm) lower than theoretical enthalpy of melting (ΔHmi). Meanwhile, the thermogravimetry degradation of the PVOH–glycerol–cassava starch can be divided into three phases, whereby phase 1 is the vaporization of volatiles, phase 2 is the rapid decomposition/dehydration and elimination of degradants and phase 3 is the formation of carbonaceous residues. These samples have thermogravimetry degradation activation energy (Ea) higher than their original components. For instance, 20 wt.% of PVOH–glycerol blended with CSS has a Ea which is 6.36 and 4.07 times higher than glycerol plasticized PVOH and CSS, respectively. Blending of PVOH–glycerol and CSS are favorable to produce biodegradable compounds resist to thermal attacks.

This study aims to investigate the hydrogen bonding interactions in polyvinyl alcohol (PVOH)–starch blends. Semi-empirical AM1 (Austin Model 1) and PM3 (Parameterized Austin Model 3) methods were employed to model the blending. Binding energies, vibrational frequencies and solubility parameters results were used to analyze the compatibility and stability of the blends. Besides that, experimental infrared spectroscopy was also conducted to validate the modeling results. The computed negative binding energies justified the stability of the blending. On the other hand, the solubility parameters of PVOH and starch modeling complexes have been found close to each other. This confirms that PVOH and starch are compatible blends. In addition, vibrational frequency analysis of these molecular complexes has exhibited that the hydroxyl group shifts to lower wavenumbers due to formation of hydrogen bonds. Findings from the experimental infrared spectroscopy have shown agreement with computational vibrational frequency results. The wavenumbers of the specimens increase is dependent on the ratios of PVOH in the blends. Such increment indicates that PVOH and starch interact in a harmonize manner and the blending is compatible.

When hydrophilic starch is incorporated into synthetic polymers, the resulting products are weakened, especially blending with hydrophobic polymers. Many researchers have been undertaking various approaches to improve compatibility of starch and synthetic polymers. However, no ultimate and comprehensive approach can be determined. This paper aims to investigate and discuss the improvement approaches which have been recently developed by researchers. Also, the extents of improvement are summarized as well. In order to simplify this review, synthetic polymers are categorized into polar and non-polar types. Low density polyethylene was studied as non-polar type polymer, while polyvinyl alcohol was studied to represent as polar type polymer. Both types of synthetic polymers were blended with starches and their results were reported well by researchers. All findings are very informative and further encourage research for other starch filled polymer systems as well. In short, appropriate modifications to starch filled polymer system would induce polarity of the materials and subsequently create harmonious intermolecular interactions among blending components for better product properties.

This paper reports the properties of newly developed electrically conductive natural fiber paper sheet made up of kenaf fiber (KF) incorporated with polyaniline coated kenaf fiber (KF-PANI). This study proposed on dispersion of conductive filler in different amount (wt %) into kenaf pulp for developing different electrical conductivity. The conductive sheet (KF/KF-PANI) revealed a percolation concentration at 25 wt% of KF-PANI. Its scanning electron micrograph showed good paper formation with no significant damages.

This short review discusses recent research regarding conductive polymeric blends containing polyaniline (PANI). Conducting PANI was reviewed in view of their properties to be used as a conducting component in several polymer matrix composites. Conductive PANI blends shows promise since the discovery of conducting polymers itself. These composite materials have introduced practical applications in various fields, including electromagnetic shielding and microwave absorption, static electricity dissipation, conducting membrane materials, conductive paint coatings and sensor materials. Highlights were made on PANI containing composites of polyethylene, polyamides, rubbers and elastomers, including other conventional thermoplastics and thermosets. Their electrical properties (percolation threshold and resistivity), blends preparation, drawbacks and potential usage were discussed in detail.

PLA/starch films were prepared by using three different solvent which is consist of chloroform, acetonitrile, and tetrahydrofuran. Similarly, composite films prepared using co-solvent of choloroform-acetonitrile (C-Ac) and choloroform- tetrahydrofuran (C-THF) were also investigated. Their properties were characterized by using TGA, DSC, IR spectroscopy and SEM. It was found that the acetonitrile casted biodegradable film achieved superior properties compared to films prepared by Ac, THF, C-Ac and C-THF.

The synergistic interaction of polyvinyl alcohol (PVOH) and cassava starch was studied by differential scanning calorimetry (DSC) method. Film of the PVOH–cassava starch blends were prepared by solution cast method. Originally, cassava starch film did not show presence of any endothermic peaks in DSC thermogram. However, after adding PVOH to cassava starch, the PVOH–cassava starch blend films showed obvious endothermic peaks with onset and end-point temperatures higher than neat PVOH film. In addition, the PVOH–cassava starch blends have experimental enthalpy of melting higher than theoretical values. This evidence shows that the interactions between PVOH and cassava starch molecules are extensively strong. Due to the synergistic interactions of PVOH and cassava starch, it is postulated that incorporation of 65–75 wt.% of PVOH in cassava starch blend has physical bonding equivalent to neat PVOH.

The properties of poly(lactic acid) (PLA) are significantly influenced by the stereochemistry of its monomers. When PLA has high stereochemical purity, it tends to form a highly crystalline structure. Copolymerization of different lactide isomers can yield a variety of PLA characteristics. The effect of isomerization in PLA can be detected by infrared and nuclear magnetic resonance spectroscopic methods. Many studies have proven that PLA has low solubility in a wide range of solvents/liquids, such as water, alcohol, and paraffin.

The aim of this study is to develop degradable starch-based packaging film with enhanced mechanical properties. A series of low-density polyethylene (LDPE)/tapioca starch compounds with various tapioca starch contents were prepared by twin-screw extrusion with the addition of maleic anhydride-grafted polyethylene as compatibilizer. Palm cooking oil was used as processing aid to ease the blown film process; thus, degradable film can be processed via conventional blown film machine. Studies on their mechanical properties and biodegradation were carried out by tensile test and exposure to fungi environment, respectively. The presence of high starch contents had an adverse effect on the tensile properties of LDPE/tapioca starch blends. However, the addition of compatibilizer to the blends improved the interfacial adhesion between the two materials and hence improved the tensile properties of the films. High content of starch was also found to increase the rate of biodegradability of LDPE/tapioca starch films. It can be proved by exposure of the film to fungi environment. A growth of microbes colony can be seen on the surface of LDPE/tapioca starch film indicates that the granular starch present on the surface of the polymer film is attacked by microorganisms, until most of it is assimilated as a carbon source.