Displaying publications 81 - 100 of 300 in total

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  1. Utilization of green banana flour as a functional ingredient in yellow noodle
    Saifullah, R., Abbas, F.M.A., Yeoh, S.Y., Azhar, M.E.
    International Food Research Journal, 2009;16(3):373-379.
    MyJurnal
    Banana pulp (BP) noodles prepared by partial substitution of wheat flour with green Cavendish banana pulp flour were assessed pH, color, tensile strength and elasticity, and in-vitro hydrolysis index (HI) and estimated glycemic index (GI). BP noodles had lower L* (darker) and b* values (less yellow) but higher tensile strength and elasticity modulus than control noodles. Following an in-vitro starch hydrolysis studies, it was found that GI of BP noodles was lower than control noodles. Partial substitution of green banana pulp into noodles may be useful for controlling starch hydrolysis of yellow noodles.
    Matched MeSH terms: Tensile Strength
  2. Fulltext Contact angle and surface free energy of PVC and Eudragit RS 100 in binary mixture study
    Mohd Cairul Iqbal Mohd Amin, Fell, J.T.
    Jurnal Sains Kesihatan Malaysia, 2006;4(1):1-8.
    MyJurnal
    Polyvinyl chloride (PVC) and ammonio methacrylate copolymer (Eudragit RS 100) were used as models in binary mixture tablets of direct compression study. Eudragit RS 100 is a copolymer synthesized from acrylic and methacrylic acid esters with a low content of quaternary ammonium groups. Combination of PVC and Eudragit RS 100 of different polarities and knowing the surface free energy values allow the possibility of predicting the tensile strength of the tablets. Specimens of 500 mg in the form of thin plates (25 mm x 12.5 mm), were made by compressing each powder at 20 000 MP a compression pressure using a special punch and die set. A Howden Universal Testing Machine was used to compress the powder. Contact angle measurements of the samples were carried out using a Wilhelmy balance, ran by a Cahn Dynamic Contact Angle Machine while different test liquids media such as water, glycerol, formamide and PEG 200 were used in the study. The surface free energy values of the solid materials were calculated using Wu's equation. The results showed large differences between the advancing and receding contact angle values for both materials when tested with glycerol: PVC (0) and PVC (0,) were 93.2 and 65.24 while Eudragit RS 100 (0) and Eudragit RS 100 (0) were 94.56 and 68.18 respectively. The surface free energy values for PVC using PEG 200-glycerol liquid pair were Is: 38.01, ysci: 33.42, ysP: 4.59 and for Eudragit RS 100 using formamide-glycerol liquid pair were ys: 75.03, yd: 51.66, ysP : 23.37, respectively. The results showed harder solid material like Eudragit RS 100 had higher surface free energy compared to elastic material like PVC.
    Matched MeSH terms: Tensile Strength
  3. Fulltext Vulcanisation and coagulant dipping of epoxidised natural rubber latex
    Dazylah Darji, Ma'zam Md Said
    Pertanika Journal of Science & Technology, 2010;18(2):-.
    MyJurnal
    Epoxidised Natural Rubber (ENR) is now a commercially available polymer produced by chemical modification of natural rubber. Currently, three types of ENR are commercially available, and these are ENR 10, ENR 25, and ENR 50 with 10%, 25%, and 50% mol epoxidation, respectively. Studies on prevulcanisation of ENR 50 and postvulcanisation of the latex films were carried out. The objective of this study was to develop ENR 50 that could be dipped easily in coagulant dipping solution to produce dipped products. Several attempts were made by compounding prevulcanised ENR 50 at various sulphur levels ranging from 0.5 to 3.0 pphr. Using suitable coagulant dipping systems, ENR 50 film could be formed despite the high contents of non-ionic surfactant. It was found that the tensile strength of prevulcanised ENR 50 film decreased with the increase in the sulphur level. The results show that as level of sulphur increased, M300 also increased to an optimum value of 1.5 pphr of sulphur. For the postvulcanised ENR 50 film, however, the tensile strength increased and then decreased with the increasing sulphur level. Meanwhile M300 increased with the increasing postvulcanization time and sulphur level. The postvulcanisation of ENR 50 film seems to be a more effective way of increasing tensile properties than by prevulcanisation of ENR 50.
    Matched MeSH terms: Tensile Strength
  4. Fulltext Induced tensile properties with EB- cross linking of hybridized kenaf/palf reinforced HDPE composite
    Aji, I.S., Zinudin, E.S., Khairul, M.Z., Abdan, K., S. M. Sapuan
    Pertanika Journal of Science & Technology, 2013;21(1):135-140.
    MyJurnal
    Electron beam irradiation, without any addition of cross-linking agents, was investigated at varying
    doses of EB-Irradiation to develop an environmentally friendly hybridized kenaf (bast)/ pineapple leaf
    fibre (PALF) bio-composites. Improvement in tensile property of the hybrid was achieved with the result
    showing a direct proportionality relationship between tensile properties and increasing radiation dose.
    Statistical analysis software (SAS) was employed to validate the result. HDPE has been shown to have
    self-cross-linked, enabling interesting tensile properties with irradiation. Statistical analysis validated
    the results obtained and also showed that adequate mixing of fibres and matrix had taken place at 95%
    confidence level. Hybridization and subsequent irradiation increased the tensile strength and modulus
    of HDPE up to 31 and 185%, respectively, at about 100kGy. Meanwhile, SEM was used to view the
    interaction between the fibres and matrix.
    Matched MeSH terms: Tensile Strength
  5. Fulltext Enhancement of tensile strength of oil palm mesocarp fiber/poly(butylene succinate) biocomposite via superheated steam-alkali treatment of oil palm mesocarp fiber
    Then, Yoon Yee, NorAzowa Ibrahim, Norhazlin Zainuddin, Hidayah Ariffin, Wan MdZin Wan Yunus
    Scientific Research Journal, 2014;11(2):0-0.
    MyJurnal
    Natural fiber is incompatible with hydrophobic polymer due to its hydrophilic nature. Therefore, surface modification of fiber is needed to impart compatibility. In this work,superheated steam (SHS)-alkali was introduced as novel surface treatment method to modify oil palm mesocarp fiber (OPMF) for fabrication of biocomposites. The OPMF was first pre-treated with SHS and subsequently treated with varying NaOH concentration (1, 2, 3, 4 and 5%) and soaking time (1, 2, 3 and 4h) at room temperature. The biocomposites were then fabricated by melt blending of 70 wt% SHS-alkali treated-OPMFs and 30 wt% poly(butylene succinate) in a Brabender internal mixer followed by hot-pressed moulding. The combination treatment resulted in fiber with rough surface as well as led to the exposure ofmicrofibers. The tensile test result showed that fiber treated at 2% NaOH solution and 3h soaking time produced biocomposite with highest improvement in tensile strength (69%) and elongation at break (36%) in comparison to that of untreated OPMF. The scanning electron micrographs of tensile fracture surfaces of biocomposite provide evident for improved adhesion between fiber and polymer after thetreatments.This work demonstrated that combination treatments of SHS and NaOH could be a promising way to modify OPMF for fabrication of biocomposite.
    Matched MeSH terms: Tensile Strength
  6. Fulltext Development and Characterization of Biodegradable Composite Films Based on Gelatin Derived from Beef, Pork and Fish Sources
    Nur Hanani ZA, Beatty E, Roos YH, Morris MA, Kerry JP
    Foods, 2013 Jan 02;2(1):1-17.
    PMID: 28239092 DOI: 10.3390/foods2010001
    The objectives of this study were to develop composite films using various gelatin sources with corn oil (CO) incorporation (55.18%) and to investigate the mechanical and physical properties of these films as potential packaging films. There were increases (p < 0.05) in the tensile strength (TS) and puncture strength (PS) of films when the concentration of gelatin increased. The mechanical properties of these films were also improved when compared with films produced without CO. Conversely, the water barrier properties of composite films decreased (p < 0.05) when the concentration of gelatin in composite films increased. Comparing with pure gelatin films, water and oxygen barrier properties of gelatin films decreased when manufactured with the inclusion of CO.
    Matched MeSH terms: Tensile Strength
  7. Fulltext UV-curable palm oil based-urethane acrylate/clay nanocomposites
    Salih, A.M., Wan Md. Zin Wan Yunus, Khairul Zaman Mohd Dahlan, Mohd Hilmi Mahmood, Mansor Ahmad
    Pertanika Journal of Science & Technology, 2012;20(2):435-444.
    MyJurnal
    Synthesis of palm oil based-urethane acrylate (POBUA) resins was carried out by acrylation of epoxidizedpalm oil (EPOP) using acrylic acid in the presence of a catalyst and followed by isocyanation to obtainthe POBUA. Using the monomer as a diluent in the formulation, 4% of photoinitiator and incorporationof organoclay (1-5% wt), nanocomposites were obtained upon UV irradiation. The X-ray DiffractoryXRD study revealed that the nanocomposites obtained were of the exfoliation type. The presence ofthe clay improved the hardness and did not affect the thermal stability. Similarly, it increased the glasstransition temperature Tg but reduced the modulus as the clay content was increased. The improvementof the tensile strength was only obtained when the clay concentration was 5 phr.
    Matched MeSH terms: Tensile Strength
  8. Fulltext Effects of alkali treatments on the tensile properties of pineapple leaf fibre reinforced high impact polystyrene composites
    Siregar, J.P., Sapuan, S.M., Rahman, M.Z.A., Zaman, H.M.D.K.
    Pertanika Journal of Science & Technology, 2012;20(2):409-414.
    MyJurnal
    A study on the effects of alkali treatment and compatibilising agent on the tensile properties of pineappleleaf fibre (PALF) reinforced high impact polystyrene (HIPS) composite is presented in this paper. Thetensile properties of natural fibre reinforced polymer composites are mainly influenced by the interfacialadhesion between the matrix and the fibres. In this study, several chemical modifications were employedto improve the interfacial matrix-fibre bonding and this resulted in the enhancement of tensile propertiesof the composites. In this study, the surface modification of pineapple fibre with alkali treatments andcompatibilizer were used to improve the adhesion between hydrophilic pineapple fibre and hydrophobicpolymer matrix. There are two concentrations of NaOH treatments and compatibilizer used in this study,namely, 2 and 4 wt. %. The results show that the alkali treated fibre and the addition of compatibilisingagent in PALF/HIPS composites have improved the tensile strength and tensile modulus of the composites.
    Matched MeSH terms: Tensile Strength
  9. Fulltext Influence of CO2 flux on the properties of carbonate apatite synthesized by solid state reaction
    Jamuna, K., Noorsal, K., Zakaria, F.A., Hussin, Z.H.
    ASM Science Journal, 2010;4(1):41-47.
    MyJurnal
    Introducing CO2 flux as the carbonate source had an effect on the carbonate content of carbonate apatite (CAp) synthesized by solid state reaction. The reactants were CaCO3 and beta-tricalcium phosphate (β-TCP) and the heat treatment in air was performed at 1250ºC followed by instant cooling in CO2 flux for temperatures ranging from 800ºC room temperature (RT) . The influence of CO2 flux at various temperature drop differences in the cooling process (1250ºC RT, 1250ºC–500ºC, 1250ºC–600ºC, 1250ºC–700ºC, and 1250ºC–800ºC) was tested to optimize the carbonation degree and subsequent effects on the physical and mechanical properties of CAp. Thermally treated samples revealed an increasing degree of carbonation, achieving a maximum of 5.2 wt% at the highest (1250ºC RT) and a minimum of 2.7 wt% at the lowest (1250ºC–800ºC) temperature drop differences, respectively. This showed that the carbonate content was correlated with the increase in exposure to CO2 flux. However, consistent compressive strength, tensile strength, density and porosity were observed against increasing temperature drop differences which indicated that the degree of carbonation exerted no influence on the physical and mechanical properties of CAp. This method enabled the synthesis of solid state CAp simply by exposing calcium phosphate mixtures to CO2 flux. It also allowed the control of carbonate content for desired medical applications.
    Matched MeSH terms: Tensile Strength
  10. Fulltext Mechanical properties of wood-wool cement composite board manufactured using selected Malaysian fast grown timber species
    Ahmad, Z., Wee, L.S., Fauzi, M.A.
    ASM Science Journal, 2011;5(1):27-35.
    MyJurnal
    This paper reports the mechanical properties of cement composite boards made using wood-wool from a lesser known Malaysian timber species. A total of 108 specimens were fabricated using Portland cement (Type I) and wood-wool from Kelampayan (Neolamarckia cadamba). The cement to wood ratio of the specimens was 2 to 1 by weight. The aim of the study was to determine the density; flexural, compressive and tensile strength of wood-wool cement composite boards (WWCCB) by studying boards with wood-wool sized 1.5 mm, 2.5 mm and 3.5 mm and board thickness 25 mm, 50 mm and 75mm. The physical and mechanical properties of the boards were evaluated according to ASTM D 1037-96a (Standard testing method for evaluating properties of wood-based fibre and particle panel materials) and MS934:1986. Results showed that mechanical properties of WWCCB were greatly influenced by the density; as the density decreased, the mechanical strengths also decreased. However, the strength properties of the composite boards did not display a similar trend when subjected to different types of loading conditions. The compressive strength increased with thicker boards (50 mm and 75 mm) but the modulus of elasticity and modulus of rupture declined as the thickness of the board was increased.
    Matched MeSH terms: Tensile Strength
  11. Fulltext Effects of soil burial on properties of linear density polyethylene (LDPE)/ thermoplastic sago starch (TPSS) blends
    Hanafi Ismail, Rohani Abdul Majid, Razaina Mat Taib
    Pertanika Journal of Science & Technology, 2011;19(1):189-197.
    MyJurnal
    Linear density polyethylene (LDPE)/thermoplastic sago starch (TPSS), blended with and without the addition of compatibilizer [Polyethylene-grafted-Maleic Anhydride, (PE-g-MA)] were prepared for soil burial test. The test was conducted in the natural soil environment for 3 and 6 months. Different loading of TPSS (10, 20, 30, 40, and 50 wt. %) were used in this study. After soil burial, the blends were evaluated for their tensile properties and scanning electron microscopy (SEM) to observe the surface morphology properties after the test. For LDPE/TPSS, it was observed that the tensile strength decreased with the increase of soil burial time, as well as Young modulus and elongation at break (EB). The LDPE/TPSS/PE-g-MA also showed the same trend for the tensile properties, but with higher properties as compared to uncompatibilized blends. The tensile properties also decreased with the increase in the TPSS loading for both the LDPE/TPSS and LDPE/TPSS/PE-g-MA. Meanwhile,
    the scanning electron microscopy (SEM) on the blend surfaces after the soil burial test showed that degradability increased with the increase in the exposure time as well as the TPSS loading.
    Matched MeSH terms: Tensile Strength
  12. Effect of Aging and Weathering on the Physical Properties of Maxillofacial Silicone Elastomers: A Systematic Review and Meta-Analysis
    Rahman AM, Jamayet NB, Nizami MMUI, Johari Y, Husein A, Alam MK
    J Prosthodont, 2019 Jan;28(1):36-48.
    PMID: 30043482 DOI: 10.1111/jopr.12950
    PURPOSE: This systematic review aims to identify and interpret results of studies that evaluated the changes in the physical properties of maxillofacial prosthetic materials (1) without aging, (2) after natural or artificial accelerated aging, and (3) after outdoor weathering.

    METHODS: Relevant articles written in English only, before January 15, 2017, were identified using an electronic search in the PubMed, Scopus, and Google Scholar databases. Furthermore, a manual search of the related major journals was also conducted to identify more pertinent articles. The relevancy of the articles was verified by screening the title, abstract, and full text if they met the inclusion criteria. A total of 37 articles satisfied the criteria, from which data were extracted for qualitative synthesis.

    RESULTS: Among the 37 included articles, 14 were without aging, 15 were natural or artificial accelerated aging, 7 were outdoor weathering, and 1 contained both artificial aging and outdoor weathering. Only 4 studies out of the 14 without aging had significant observations; whereas 9 articles with natural or artificial aging published significant results, and 3 out of 7 outdoor weathering articles showed significant changes in the evaluated silicone elastomers.

    CONCLUSIONS: Despite the varying research, it seems that the single "ideal" maxillofacial prosthetic material that can provide sufficient resistance against different aging conditions is yet to be identified. Therefore, it is imperative for standardization organizations, the scientific community, and academia to develop modified prosthetic silicones possessing improved physical properties and color stability, limiting the clinical problems regarding degradation of maxillofacial prostheses.

    Matched MeSH terms: Tensile Strength
  13. Fulltext Development and characterisation of Vitex negundo Linn. noodles
    Tan, L.S., Leila, M., Rabeta, M.S.
    Food Research, 2018;2(1):68-75.
    MyJurnal
    Formulation 2 (1 g w/w) was the most favourable and was chosen for further analyses to
    compare its composition with that of a control (0 g w/w). Total phenolic content (TPC) of
    the fresh noodles remained higher than that of the control even after cooking. However,
    after cooking, the carbohydrate and protein contents showed significant increases. The
    results showed that the lemuni-supplemented noodles have a longer shelf life compared to
    the control. The colour parameters L* and a* also showed significant differences as the
    lightness decreased, and the redness increased after the substitution. The L*, a* and b*
    values decreased significantly after the noodles of both formulations were cooked. The
    tensile strength, adhesiveness, and hardness of the lemuni noodles were significantly
    higher than those of the control. Thus, the Vitex negundo Linn. leaf has the potential to
    increase the health benefits of food products.
    Matched MeSH terms: Tensile Strength
  14. Fulltext Influence of alkylphosphonium modified montmorillonite to the tensile properties of PMMA composites
    Abdullah, M.A.A., Mamat, M., Rusli, S.A., Kassim, A.A.
    ASM Science Journal, 2018;11(101):96-104.
    MyJurnal
    Considering its excellent thermal stability, alkyl phosphonium surfactant: triisobutyl(methyl)phosphonium
    (TIBMP) was used in this research as an intercalant for surface
    modification of Na+-MMT via ion exchange process forming organomontmorillonite
    (OMMT). The OMMT was then used as filler in poly(methyl methacrylate) (PMMA) via
    melt intercalation technique. OMMT decomposed at a higher temperature than commercial
    alkyammonium modified MMT. Exfoliated and intercalated types of nanocomposites
    are obtained from PMMA/OMMTs at low and high content of OMMT loading, depending
    on the space of those clay platelets had to disperse in PMMA. The ability of OMMT to
    carry a certain load applied in PMMA matrix enhances the tensile strength in all composites.
    TIBMP are compatible with PMMA matrix, and significantly improves the tensile
    properties of PMMA composites.
    Matched MeSH terms: Tensile Strength
  15. Fulltext Mechanical and physical properties of gellan gum (GG) biofilm: effect of glycerol
    Razali, M.H., Ismail, N.A., Osman, U.M., Amin, K.A.M.
    ASM Science Journal, 2018;11(101):158-165.
    MyJurnal
    The aim of this work was to investigate the effect of glycerol concentration on mechanical
    and physical properties of gellan gum (GG) biofilm. The biofilm was prepared using solvent
    casting method and the effective glycerol concentration was found to be within 30-50%
    w/w (based on GG weight). At 60 and 70 w/w% of glycerol, the films started to distort
    because the films was flexible and brittle. As glycerol concentration was increased the tensile
    strength (TS) and Youngs modulus (E) of films decreased. Somehow, elongation at break
    (EAB), water vapor transmission rate (WVTR) and swelling of films was increased. Glycerol
    plasticized GG biofilm was thermally stable and flexible, proposed its can be exploited as
    film-forming material and with optimized glycerol concentration it has good mechanical and
    physical properties for edible biofilm.
    Matched MeSH terms: Tensile Strength
  16. Fulltext Assessments of Secondary Reinforcement of Epoxy Matrix-Glass Fibre Composite Laminates through Nanosilica (SiO₂)
    Lazar PJL, Sengottuvelu R, Natarajan E
    Materials (Basel), 2018 Nov 05;11(11).
    PMID: 30400592 DOI: 10.3390/ma11112186
    The principal objective of this research work was to investigate the results of impregnating epoxy matrix-glass fibre composite laminates with nanosilica as secondary reinforcement. 0.5, 0.75, 1 and 3 wt% nanosilica was used and thereafter properties of composites were assessed through tensile, three point bending, quasi static indentation tests and dynamic mechanical analysis. Scanning electron microscope examinations were done on fracture surfaces and failure modes were analyzed. The internal failures of the composite due to quasi-static indentation were evaluated through C-Scan. Among samples of different weight fractions, 0.75 wt% nanosilica reinforced composite laminates exhibited substantial increase of 42% in tensile strength and 39.46% in flexural strength. The reduction in glass transition temperature (Tg), increase in storage modulus (E'), loss modulus (E″) and damping factor (tan δ) were also observed. Quasi-static indentation assessments revealed that energy absorption property was enhanced significantly by 53.97%. Hence nanosilica up to 0.75 wt% can be used as a potential candidate for secondary reinforcement in epoxy composite laminates.
    Matched MeSH terms: Tensile Strength
  17. Fulltext Properties and Characterization of a PLA-Chitin-Starch Biodegradable Polymer Composite
    Olaiya NG, Surya I, Oke PK, Rizal S, Sadiku ER, Ray SS, et al.
    Polymers (Basel), 2019 Oct 11;11(10).
    PMID: 31614623 DOI: 10.3390/polym11101656
    This paper presents a comparison on the effects of blending chitin and/or starch with poly(lactic acid) (PLA). Three sets of composites (PLA-chitin, PLA-starch and PLA-chitin-starch) with 92%, 94%, 96% and 98% PLA by weight were prepared. The percentage weight (wt.%) amount of the chitin and starch incorporated ranges from 2% to 8%. The mechanical, dynamic mechanical, thermal and microstructural properties were analyzed. The results from the tensile strength, yield strength, Young's modulus, and impact showed that the PLA-chitin-starch blend has the best mechanical properties compared to PLA-chitin and PLA-starch blends. The dynamic mechanical analysis result shows a better damping property for PLA-chitin than PLA-chitin-starch and PLA-starch. On the other hand, the thermal property analysis from thermogravimetry analysis (TGA) shows no significant improvement in a specific order, but the glass transition temperature of the composite increased compared to that of neat PLA. However, the degradation process was found to start with PLA-chitin for all composites, which suggests an improvement in PLA degradation. Significantly, the morphological analysis revealed a uniform mix with an obvious blend network in the three composites. Interestingly, the network was more significant in the PLA-chitin-starch blend, which may be responsible for its significantly enhanced mechanical properties compared with PLA-chitin and PLA-starch samples.
    Matched MeSH terms: Tensile Strength
  18. Fulltext Polypropylene/Graphene Nanocomposites: Effects of GNP Loading and Compatibilizers on the Mechanical and Thermal Properties
    Al-Saleh MA, Yussuf AA, Al-Enezi S, Kazemi R, Wahit MU, Al-Shammari T, et al.
    Materials (Basel), 2019 Nov 27;12(23).
    PMID: 31783544 DOI: 10.3390/ma12233924
    In this research work, graphene nanoplatelets (GNP) were selected as alternative reinforcing nanofillers to enhance the properties of polypropylene (PP) using different compatibilizers called polypropylene grafted maleic anhydride (PP-g-MA) and ethylene-octene elastomer grafted maleic anhydride (POE-g-MA). A twin screw extruder was used to compound PP, GNP, and either the PP-g-MA or POE-g-MA compatibilizer. The effect of GNP loading on mechanical and thermal properties of neat PP was investigated. Furthermore, the influence and performance of different compatibilizers on the final properties, such as mechanical and thermal, were discussed and reported. Tensile, flexural, impact, melting temperature, crystallization temperature, and thermal stability were evaluated by using a universal testing system, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). For mechanical properties, it was found that increasing GNP content from 1 wt.% to 5 wt.% increased tensile strength of the neat PP up to 4 MPa. The influence of compatibilizers on the mechanical properties had been discussed and reported. For instance, the addition of PP-g-MA compatibilizer improved tensile strength of neat PP with GNP loading. However, the addition of compatibilizer POE-g-MA slightly decreased the tensile strength of neat PP. A similar trend of behavior was observed for flexural strength. For thermal properties, it was found that both GNP loading and compatibilizers have no significant influence on both crystallization and melting temperature of neat PP. For thermal stability, however, it was found that increasing the GNP loading had a significant influence on improving the thermal behavior of neat PP. Furthermore, the addition of compatibilizers into the PP/GNP nanocomposite had slightly improved the thermal stability of neat PP.
    Matched MeSH terms: Tensile Strength
  19. Kesan Komposisi Gentian dan Kaedah Pemprosesan ke atas Sifat Mekanik Komposit NR/LLDPE diperkuat Twaron (Effect of Fiber Composition and Processing Methods on the Mechanical Properties of Twaron Reinforced NR/LLDPE Composites)
    Ishak Ahmad, Mohd Khairil Saat, Ibrahim Abdullah, Azizah Baharum
    Sains Malaysiana, 2004;33.
    Blends of fibre-reinforced rubber based on natural rubber-thermoplastic (NR/LLDPE) reinforced by aramid fibre have been done using melt blending process. Two different processing methods were used; internal mixer and extrusion compounding in twin screw extruder. Twaron loading in the system was varied from 0 to 30%. It was found that increasing the amount of aramid fibre led to an increase in the tensile strength, tensile modulus and hardness of the composites while the strain decreased rapidly. The results showed that the optimum composition of filler loading in NR/LLDPE blend is 20%. The ,echanical behaviour was caused by the strong Twaron-matrices interaction in the composites and effective stress concentrating function of Twaron. Composites prepared using the twin-screw extruder have a higher tensile strength and tensile using the twin-screw extruder have a higher tensile stength and tensile modulus but lower impact strength compared to those prepared using internal mixer. Study of the fracture surface by scanning electron microscopy showed that the composite prepared using the internal mixer produced random fiber orientation while the twin-screw extruder produced the fibers aligned to the longitudinal direction. The results indicate that the mechanical properties of the composite were significantly influenced by the processing technique.
    Penyediaan komposit getah asli termoplastik daripada NR/LLDPE yang diperkuat gentian Twaron telah dijalankan melalui proses adunan leburan. Dua kaedah penyediaan yang berbeza digunakan iaitu menggunakan mesin pencampur dalaman manakala kaedah kedua menggunakan pengekstrud skru kembar. Kandungan Twaron di dalam komposit telah diubah daripada 0 hingga 30%. Keputusan menunjukkan bahawa penambahan Twaron telah meningkatkan nilai tegasan maksima, modulus Young dan kekuatan hentaman komposit tetapi menurunkan nilai terikan maksima. Kandungan Twaron yang optimum adalah 20%. Kehadiran Twaron telah membentuk satu jaringan saling tindak gentian-matriks menyebabkan kekuatan regangan komposit meningkat. Twaron juga berfungsi sebagai penyerap hentaman yang berkesan. Penyediaan komposit menggunakan pengekstrud skru berkembar telah menghasilkan nilai kekuatan regangan yang lebih tinggi berbanding penggunaan pencampur dalaman sebaliknya kekuatan hentaman yang lebih rendah. Kajian morfologi menggunakan mikroskop imbasan elektron mendapati komposit yang disediakan menggunakan pencampur dalaman menghasilkan gentian dengan orientasi rawak manakala pengekstrud skru kembar menghasilkan orientasi gentian yang selari. Keputusan ini menunjukkan bahawa sifat mekanik komposit NR/LLDPE yang diperkuat Twaron sangat dipengaruhi oleh teknik pemprosesan.
    Matched MeSH terms: Tensile Strength
  20. Tensile properties of vulcanized field natural rubber latex by electron beam
    Chai CK, Md. Soot Ahmad, Wan Manshol W. Zin
    Sains Malaysiana, 2008;37.
    Electron beam vulcanization of natural rubber latex has been developed as an alternative to the conventional sulphur vulcanization method. This study aimed at determining the effect of electron beam dose, beam current and centrifugation to the tensile properties of field natural rubber latex. Irradiation dose and beam current ranged from 50 to 300 kGy and 1 to 15 mA respectively. The determination of tensile properties were done on cast film prepared from irradiated field latex before and after centrifugation. It was found that tensile properties increased with radiation dose but decreased with beam current. Rubber films made from centrifuged irradiated field latex were softer and showed higher tensile strength.
    Matched MeSH terms: Tensile Strength
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