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Fulltext Biodegradable Gloves for Waste Management Post-COVID-19 Outbreak: A Shelf-Life Prediction

Ab Rahman MF, Rusli A, Misman MA, Rashid AA

ACS Omega, 2020 Nov 24;5(46):30329-30335.
PMID: 33251468 DOI: 10.1021/acsomega.0c04964

With increased awareness on the importance of gloves arising from the COVID-19 pandemic, people are expected to continue using them even after the pandemic recedes. This scenario in a way increased the rubber solid waste disposal problem; therefore, the production of biodegradable gloves may be an option to overcome this problem. However, the need to study the shelf life of biodegradable gloves is crucial before commercialization. There are well-established models to address the failure properties of gloves as stated in the American Society for Testing and Material (ASTM) D7160. In this study, polysaccharide-based material-filled natural rubber latex (PFNRL) gloves, which are biodegradable gloves, were subjected to an accelerated aging process at different temperatures of 50-80 °C for 1-120 days. Prediction models based on Arrhenius and shift factors were used to estimate the shelf life of the PFNRL gloves. Based on the results obtained, the estimated time for the PFNRL gloves to retain 75% of their tensile strength at shelf temperature (30 °C) based on Arrhenius and shift factor models was 2.8 years. Verification on the activation energy based on the shift factor model indicated that the shelf life of PFNRL gloves is 2.9 years, which is only a 3.6% difference. The value obtained is aligned with the requirement in accordance with ASTM D7160, which states that only up to a maximum of 3 years' shelf life is allowed for the gloves under accelerated aging conditions.

Matched MeSH terms: Tensile Strength
Fulltext Carbon Nanotubes (CNTs)-Reinforced Magnesium-Based Matrix Composites: A Comprehensive Review

Abazari S, Shamsipur A, Bakhsheshi-Rad HR, Ismail AF, Sharif S, Razzaghi M, et al.

Materials (Basel), 2020 Oct 04;13(19).
PMID: 33020427 DOI: 10.3390/ma13194421

In recent years considerable attention has been attracted to magnesium because of its light weight, high specific strength, and ease of recycling. Because of the growing demand for lightweight materials in aerospace, medical and automotive industries, magnesium-based metal matrix nanocomposites (MMNCs) reinforced with ceramic nanometer-sized particles, graphene nanoplatelets (GNPs) or carbon nanotubes (CNTs) were developed. CNTs have excellent material characteristics like low density, high tensile strength, high ratio of surface-to-volume, and high thermal conductivity that makes them attractive to use as reinforcements to fabricate high-performance, and high-strength metal-matrix composites (MMCs). Reinforcing magnesium (Mg) using small amounts of CNTs can improve the mechanical and physical properties in the fabricated lightweight and high-performance nanocomposite. Nevertheless, the incorporation of CNTs into a Mg-based matrix faces some challenges, and a uniform distribution is dependent on the parameters of the fabricating process. The characteristics of a CNTs reinforced composite are related to the uniform distribution, weight percent, and length of the CNTs, as well as the interfacial bonding and alignment between CNTs reinforcement and the Mg-based matrix. In this review article, the recent findings in the fabricating methods, characterization of the composite's properties, and application of Mg-based composites reinforced with CNTs are studied. These include the strategies of fabricating CNT-reinforced Mg-based composites, mechanical responses, and corrosion behaviors. The present review aims to investigate and conclude the most relevant studies conducted in the field of Mg/CNTs composites. Strategies to conquer complicated challenges are suggested and potential fields of Mg/CNTs composites as upcoming structural material regarding functional requirements in aerospace, medical and automotive industries are particularly presented.

Matched MeSH terms: Tensile Strength
Fulltext Improving Performance of Electrospun Nylon 6,6 Nanofiber Membrane for Produced Water Filtration via Solvent Vapor Treatment

Abd Halim NS, Wirzal MDH, Bilad MR, Md Nordin NAH, Adi Putra Z, Sambudi NS, et al.

Polymers (Basel), 2019 Dec 17;11(12).
PMID: 31861059 DOI: 10.3390/polym11122117

Electrospun nanofiber membrane (NFM) has a high potential to be applied as a filter for produced water treatment due to its highly porous structure and great permeability. However, it faces fouling issues and has low mechanical properties, which reduces the performance and lifespan of the membrane. NFM has a low integrity and the fine mat easily detaches from the sheet. In this study, nylon 6,6 was selected as the polymer since it offers great hydrophilicity. In order to increase mechanical strength and separation performance of NFM, solvent vapor treatment was implemented where the vapor induces the fusion of fibers. The fabricated nylon 6,6 NFMs were treated with different exposure times of formic acid vapor. Results show that solvent vapor treatment helps to induce the fusion of overlapping fibers. The optimum exposure time for solvent vapor is 5 h to offer full retention of dispersed oil (100% of oil rejection), has 62% higher in tensile strength (1950 MPa) compared to untreated nylon 6,6 NFM (738 MPa), and has the final permeability closest to the untreated nylon 6,6 NFM (733 L/m2.h.bar). It also took more time to get fouled (220 min) compared to untreated NFM (160 min).

Matched MeSH terms: Tensile Strength
Fulltext Enhancement of mechanical and thermal properties of polycaprolactone/chitosan blend by calcium carbonate nanoparticles

Abdolmohammadi S, Siyamak S, Ibrahim NA, Yunus WM, Rahman MZ, Azizi S, et al.

Int J Mol Sci, 2012;13(4):4508-22.
PMID: 22605993 DOI: 10.3390/ijms13044508

This study investigates the effects of calcium carbonate (CaCO(3)) nanoparticles on the mechanical and thermal properties and surface morphology of polycaprolactone (PCL)/chitosan nanocomposites. The nanocomposites of PCL/chitosan/CaCO(3) were prepared using a melt blending technique. Transmission electron microscopy (TEM) results indicate the average size of nanoparticles to be approximately 62 nm. Tensile measurement results show an increase in the tensile modulus with CaCO(3) nanoparticle loading. Tensile strength and elongation at break show gradual improvement with the addition of up to 1 wt% of nano-sized CaCO(3). Decreasing performance of these properties is observed for loading of more than 1 wt% of nano-sized CaCO(3). The thermal stability was best enhanced at 1 wt% of CaCO(3) nanoparticle loading. The fractured surface morphology of the PCL/chitosan blend becomes more stretched and homogeneous in PCL/chitosan/CaCO(3) nanocomposite. TEM micrograph displays good dispersion of CaCO(3) at lower nanoparticle loading within the matrix.

Matched MeSH terms: Tensile Strength/physiology*
Production and modification of nanofibrillated cellulose using various mechanical processes: a review

Abdul Khalil HP, Davoudpour Y, Islam MN, Mustapha A, Sudesh K, Dungani R, et al.

Carbohydr Polym, 2014 Jan;99:649-65.
PMID: 24274556 DOI: 10.1016/j.carbpol.2013.08.069

Nanofibrillated cellulose from biomass has recently gained attention owing to their biodegradable nature, low density, high mechanical properties, economic value and renewability. Although they still suffer from two major drawbacks. The first challenge is the exploration of raw materials and its application in nanocomposites production. Second one is high energy consumption regarding the mechanical fibrillation. However, pretreatments before mechanical isolation can overcome this problem. Hydrophilic nature of nano-size cellulose fibers restricts good dispersion of these materials in hydrophobic polymers and therefore, leads to lower mechanical properties. Surface modification before or after mechanical defibrillation could be a solution for this problem. Additionally, drying affects the size of nanofibers and its properties which needs to study further. This review focuses on recent developments in pretreatments, nanofibrillated cellulose production and its application in nanopaper applications, coating additives, security papers, food packaging, and surface modifications and also for first time its drying.

Matched MeSH terms: Tensile Strength
Fulltext Hybrid composites: study on un-treated kenaf/glass fibre properties

Abdul Malek Ya’acob, Azhar Abu Bakar, Hanafi Ismail, Khairul Zaman Dahlan

Pertanika Journal of Science & Technology, 2011;19(2):373-381.
MyJurnal

A hybrid composite consisting of untreated kenaf fibre and glass fibre was investigated by varying the fibre glass weight ratios and using interply fabrication method. The expected results were to have better composite performance in terms of its toughness and impact strength as a comparison between the hybrid (kenaf/E-glass fibre composites) and E-GF composites alone. For the purpose of this study, all the samples were prepared using typical sample preparation. Results show that the incorporation of E–glass fibre resulted in brittle failure and a higher amount of E-Glass fibre with low percentage of kenaf fibre causing high strength, low ductile, and low toughness behaviours.

Matched MeSH terms: Tensile Strength
Mechanical and cytotoxicity properties of hybrid ceramics filled polyamide 12 filament feedstock for craniofacial bone reconstruction via fused deposition modelling

Abdullah AM, Rahim TNAT, Hamad WNFW, Mohamad D, Akil HM, Rajion ZA

Dent Mater, 2018 11;34(11):e309-e316.
PMID: 30268678 DOI: 10.1016/j.dental.2018.09.006

OBJECTIVE: To compare the mechanical and biological properties of newly developed hybrid ceramics filled and unfilled polyamide 12 (PA 12) for craniofacial reconstruction via a fused deposition modelling (FDM) framework.
METHODS: 15wt% of zirconia (ZrO2) as well as 30, 35, and 40wt% of beta-tricalcium phosphate (β-TCP) were compounded with PA 12, followed by the fabrication of filament feedstocks using a single screw extruder. The fabricated filament feedstocks were used to print the impact specimens. The melt flow rate, tensile properties of fabricated filament feedstocks, and 3D printed impact properties of the specimens were assessed using melt flow indexer, universal testing machine, and Izod pendulum tester, respectively. The microstructure of selected filament feedstocks and broken impact specimens were analysed using a field emission scanning electron microscope and universal testing machine. Human periodontal ligament fibroblast cells (HPdLF) were used to evaluate the cytotoxicity of the materials by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid) (MTT) assay.
RESULTS: Hybrid ceramics filled PA 12 indicated sufficient flowability for FDM 3D printing. The tensile strength of hybrid ceramics filled PA 12 filament feedstocks slightly reduced as compared to unfilled PA 12. However, the tensile modulus and impact strength of hybrid ceramics filled PA 12 increased by 8%-31% and 98%-181%, respectively. A significant increase was also detected in the cell viability of the developed composites at concentrations of 12.5, 25, 50 and 100mg/ml.
SIGNIFICANCE: The newly developed hybrid ceramics filled PA 12 filament feedstock with improved properties is suitable for an FDM-based 3D printer, which enables the creation of patient-specific craniofacial implant at a lower cost to serve low-income patients.

Matched MeSH terms: Tensile Strength
Enhancement of thermal, mechanical and physical properties of polyamide 12 composites via hybridization of ceramics for bone replacement

Abdullah AM, Mohamad D, Rahim TNAT, Akil HM, Rajion ZA

Mater Sci Eng C Mater Biol Appl, 2019 Jun;99:719-725.
PMID: 30889745 DOI: 10.1016/j.msec.2019.02.007

This study reports the influence of ZrO2/β-TCP hybridization on the thermal, mechanical, and physical properties of polyamide 12 composites to be suited for bone replacement. Amount of 15 wt% of nano-ZrO2 along with 5,10,15,20 and 25 wt% of micro-β-TCP was compounded with polyamide 12 via a twin-screw extruder. The hybrid ZrO2/β-TCP filled polyamide 12 exhibited higher thermal, mechanical and physical properties in comparison to unfilled polyamide 12 at certain filler loading; which is attributed to the homogenous dispersion of ZrO2/β-TCP fillers particle in polyamide 12 matrix. The hybrid ZrO2/β-TCP filled PA 12 demonstrated an increment of tensile strength by up to 1%, tensile modulus of 38%, flexural strength of 15%, flexural modulus of 45%, and surface roughness value of 93%, as compared to unfilled PA 12. With enhanced thermal, mechanical and physical properties, the newly developed hybrid ZrO2/β-TCP filled PA 12 could be potentially utilized for bone replacement.

Matched MeSH terms: Tensile Strength
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
Enhanced performance with elastic resistance during the eccentric phase of a countermovement jump

Aboodarda SJ, Yusof A, Abu Osman NA, Thompson MW, Mokhtar AH

Int J Sports Physiol Perform, 2013 Mar;8(2):181-7.
PMID: 23428490

To identify the effect of additional elastic force on the kinetic and kinematic characteristics, as well as the magnitude of leg stiffness, during the performance of accentuated countermovement jumps (CMJs).

Matched MeSH terms: Tensile Strength
Performance of a novel casing made of chitosan under traditional sausage manufacturing conditions

Adzaly NZ, Jackson A, Kang I, Almenar E

Meat Sci, 2016 Mar;113:116-23.
PMID: 26656870 DOI: 10.1016/j.meatsci.2015.11.023

The goal of this study was to validate the commercial feasibility of a novel casing formed from chitosan containing cinnamaldehyde (2.2%, w/v), glycerol (50%, w/w) and Tween 80 (0.2% w/w) under traditional sausage manufacturing conditions. Meat batter was stuffed into both chitosan and collagen (control) casings and cooked in a water bath. Before and after cooking, both casings were compared for mechanical, barrier, and other properties. Compared to collagen, the chitosan casing was a better (P≤0.05) barrier to water, oxygen, liquid smoke, and UV light. In mechanical and other properties, the chitosan casing had higher (P≤0.05) tensile strength, lower (P≤0.05) elongation at break and tensile energy to break, and better (P≤0.05) transparency whereas a similar (P>0.05) water solubility to the collagen casing. Overall, the chitosan casing was less affected by sausage manufacturing conditions than the collagen casing, indicating that chitosan casing has potential as an alternative to the current collagen casing in the manufacture of sausages.

Matched MeSH terms: Tensile Strength
Biodegradability of degradable plastic waste

Agamuthu P, Faizura PN

Waste Manag Res, 2005 Apr;23(2):95-100.
PMID: 15864950

Plastic waste constitutes the third largest waste volume in Malaysian municipal solid waste (MSW), next to putrescible waste and paper. The plastic component in MSW from Kuala Lumpur averages 24% (by weight), whereas the national mean is about 15%. The 144 waste dumps in the country receive about 95% of the MSW, including plastic waste. The useful life of the landfills is fast diminishing as the plastic waste stays un-degraded for more than 50 years. In this study the compostability of polyethylene and pro-oxidant additive-based environmentally degradable plastics (EDP) was investigated. Linear low-density polyethylene (LLDPE) samples exposed hydrolytically or oxidatively at 60 degrees C showed that the abiotic degradation path was oxidative rather than hydrolytic. There was a weight loss of 8% and the plastic has been oxidized as shown by the additional carbonyl group exhibited in the Fourier transform infra red (FTIR) Spectrum. Oxidation rate seemed to be influenced by the amount of pro-oxidant additive, the chemical structure and morphology of the plastic samples, and the surface area. Composting studies during a 45-day experiment showed that the percentage elongation (reduction) was 20% for McD samples [high-density polyethylene, (HDPE) with 3% additive] and LL samples (LLDPE with 7% additive) and 18% reduction for totally degradable plastic (TDP) samples (HDPE with 3% additive). Lastly, microbial experiments using Pseudomonas aeroginosa on carbon-free media with degradable plastic samples as the sole carbon source, showed confirmatory results. A positive bacterial growth and a weight loss of 2.2% for degraded polyethylene samples were evident to show that the degradable plastic is biodegradable.

Matched MeSH terms: Tensile Strength
Effects of kenaf loading and alkaline treatment on properties of kenaf filled natural rubber latex foam

Ahmad Fikri Abdul Karim, Hanafi Ismail, Zulkifli Mohamad Ariff

Sains Malaysiana, 2018;47:2163-2169.

This research was carried out to study the effects of kenaf loading and alkaline treatment on tensile properties, density,
thermal and morphological properties of kenaf filled natural rubber latex foam (NRLF). Samples were prepared using a
Dunlop method. From the results, increasing loading of kenaf reduced the tensile strength and elongation at break for
both samples, treated and untreated kenaf filled NRLF. Meanwhile, modulus at 100% elongation and density increased
with an increased in kenaf loading. Samples with treated kenaf showed higher tensile strength, modulus at 100%
elongation and density but low in elongation at break as compared with samples with untreated kenaf. Thermal study
by using thermogravimetric analysis (TGA) showed that thermal stability reduced with increased in kenaf loading for
both samples. Samples with treated kenaf have higher thermal stability compared with samples of untreated kenaf. The
filler-matrix interaction and the pores size variation of both samples was clearly seen in the micrograph images by using
scanning electron microscope (SEM).

Matched MeSH terms: Tensile Strength
Fulltext Investigation on moisture susceptibility and rutting resistance of Asphalt mixtures incorporating Nanosilica modified binder

Ahmad Kamil Arshad, Khairil Azman Masri, Juraidah Ahmad, Mohamad Saifullah Samsudin

Pertanika Journal of Science & Technology, 2017;25(103):19-30.
MyJurnal

This paper presents the outcome of a laboratory investigation on mix design, resilient modulus, moisture susceptibility and rutting resistance of Stone Mastic Asphalt (SMA) and Dense Graded Asphalt (AC) that is incorporated with Nanosilica (NS) modified binder. Penetration Grade 60-70 (PEN60-70) types of binder were mixed with nanoparticles (NS) using concentration of 0wt%, 2wt%, 4wt% and 6wt% by weight of asphalt binder. The mixtures were tested for resilient modulus, indirect tensile strength and rutting, in order to evaluate the performance of NS-SMA and NS-AC. The results show that the existence of NS is capable of enhancing the performance of both asphalt mixtures, and the addition of NS decreases the susceptibility of moisture damage and provides better resistance against permanent deformation. Furthermore, the addition of 4wt% NS appears to be the most effective amount for the performance enhancement in AC and SMA mixtures.

Matched MeSH terms: Tensile Strength
Fulltext Evaluation of cold in-place recycling mix using polymer modified Asphalt emulsion

Ahmad Kamil Arshad, Juraidah Ahmad, Mohd Izzat Asyraf Mohamad Kamal

Pertanika Journal of Science & Technology, 2017;25(107):219-226.
MyJurnal

This paper details a study conducted to evaluate the performance of cold in-place recycling (CIPR) using polymer modified asphalt emulsion (PMAE). The asphalt emulsion was modified using natural rubber latex (NRL). Four proportions of reclaimed asphalt pavement (RAP) which are 0%, 25%, 50% and 75% were mixed with natural aggregates and modified asphalt emulsion using natural rubber latex (NRL). The results showed that the optimum modified asphalt emulsion for each proportion of RAP decreased due to the increase in RAP content. Results obtained from Indirect Tensile Strength (ITS) and Uniaxial Compressive Strength (UCS) test for the mixes complied with the requirements of the Road Engineering Association of Malaysia (REAM) specifications. The unsoaked and soaked ITS values obtained were 0.2 MPa and 0.15 MPa respectively, and the minimum compressive strength of CIPR mix obtained was 0.7 MPa. Based on the evaluation of performance for the four RAP proportions, it was determined that 50% of RAP gave the best combination of the CIPR mixture.

Matched MeSH terms: Tensile Strength
Fulltext Fracture resistance tests validation: a survey of literature review

Ahmad Mahmood, Aws H. Ali Al-Kadhim, Zaripah Wan Bakar, Adam Husein

Malaysian Dental Journal, 2011;32(1):12-16.
MyJurnal

Evaluation of the mechanical behaviour of restoration dental materials is essential to understand their performance under different load conditions and to estimate their durability under clinical oral function. Restorative materials and dental tissues like other materials by having specific mechanical properties, such as static strength (i.e. compressive strength, tensile strength, flexural strength) and dynamic strength (i.e. fatigue strength). The selection of proper mechanical test type depends on the goals that the study claims to define. On such basis, the mechanical test can be chosen correctly. Laboratory studies should be designed as replications of the clinical oral circumstances to measure the mechanical and physical properties of a material and any arbitrary choices in the design of the study may result in large variations of data.

Matched MeSH terms: Tensile Strength
Cryopreservation versus fresh frozen meniscal allograft: A biomechanical comparative analysis

Ahmad S, Singh VA, Hussein SI

J Orthop Surg (Hong Kong), 2017 8 29;25(3):2309499017727946.
PMID: 28844199 DOI: 10.1177/2309499017727946

Meniscal allograft transplantation may be a better alternative for the treatment of irreparable meniscal injury compared to other forms of treatment. However, it remains to be seen whether the use fresh frozen allograft is better than cryopreserved allograft in treating this type of injury. We hypothesized that cryopreserved meniscal allograft would work better in maintaining the original biomechanical properties compared to fresh frozen ones, due to the lower amount of damage it incurs during the storage process. We examined young and healthy human menisci obtained from orthopedic oncology patients who underwent resection surgeries around the knee. The menisci obtained were preserved via cryopreservation and deep-freezing process. Traction tests were carried out on the menisci after 6 weeks of preservation. Twelve pairs ( N = 24) of menisci were divided equally into two groups, cryopreservation and deep frozen. There were six males and six female menisci donors for this study. The age range was between 15 and 35 years old (24.9 ± 8.6 years). Cryopreserved specimens had a higher ultimate tensile strength (UTS; 8.2 ± 1.3 Mpa vs. 13.3 ± 1.7 Mpa: p < 0.05) and elastic modulus (61.7 ± 27.6 Mpa vs. 87.0 ± 44.10 Mpa: p < 0.05) compared to the fresh frozen specimens. There was a significant difference in UTS ( p < 0.05) between the two groups but no significant difference in their elastic modulus ( p > 0.05). The elastic modulus of the preserved meniscus was similar to fresh normal menisci taken from other studies (60-120 Mpa; cryopreserved (87.0 ± 44.1) and fresh frozen (61.7 ± 27.5)). Cryopreserved menisci had a higher elastic modulus and point of rupture (UTS) compared to fresh frozen menisci. Cryopreservation proved to be a significantly better method of preservation, among the two methods of preservation in this study.

Matched MeSH terms: Tensile Strength
Fulltext Mechanical Strength, Thermal Conductivity and Electrical Breakdown of Kenaf Core Fiber/Lignin/Polypropylene Biocomposite

Ahmad Saffian H, Talib MA, Lee SH, Md Tahir P, Lee CH, Ariffin H, et al.

Polymers (Basel), 2020 Aug 15;12(8).
PMID: 32824275 DOI: 10.3390/polym12081833

Mechanical strength, thermal conductivity and electrical breakdown of polypropylene/lignin/kenaf core fiber (PP/L/KCF) composite were studied. PP/L, PP/KCF and PP/L/KCF composites with different fiber and lignin loading was prepared using a compounding process. Pure PP was served as control. The results revealed that tensile and flexural properties of the PP/L/KCF was retained after addition of lignin and kenaf core fibers. Thermal stability of the PP composites improved compared to pure PP polymer. As for thermal conductivity, no significant difference was observed between PP composites and pure PP. However, PP/L/KCF composite has higher thermal diffusivity. All the PP composites produced are good insulating materials that are suitable for building. All PP composites passed withstand voltage test in air and oil state as stipulated in IEC 60641-3 except PP/L in oil state. SEM micrograph showed that better interaction and adhesion between polymer matrix, lignin and kenaf core fibers was observed and reflected on the better tensile strength recorded in PP/L/KCF composite. This study has successfully filled the gap of knowledge on using lignin and kenaf fibers as PP insulator composite materials. Therefore, it can be concluded that PP/Lignin/KCF has high potential as an insulating material.

Matched MeSH terms: Tensile Strength
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
PVA-PEG physically cross-linked hydrogel film as a wound dressing: experimental design and optimization

Ahmed AS, Mandal UK, Taher M, Susanti D, Jaffri JM

Pharm Dev Technol, 2018 Oct;23(8):751-760.
PMID: 28378604 DOI: 10.1080/10837450.2017.1295067

The development of hydrogel films as wound healing dressings is of a great interest owing to their biological tissue-like nature. Polyvinyl alcohol/polyethylene glycol (PVA/PEG) hydrogels loaded with asiaticoside, a standardized rich fraction of Centella asiatica, were successfully developed using the freeze-thaw method. Response surface methodology with Box-Behnken experimental design was employed to optimize the hydrogels. The hydrogels were characterized and optimized by gel fraction, swelling behavior, water vapor transmission rate and mechanical strength. The formulation with 8% PVA, 5% PEG 400 and five consecutive freeze-thaw cycles was selected as the optimized formulation and was further characterized by its drug release, rheological study, morphology, cytotoxicity and microbial studies. The optimized formulation showed more than 90% drug release at 12 hours. The rheological properties exhibited that the formulation has viscoelastic behavior and remains stable upon storage. Cell culture studies confirmed the biocompatible nature of the optimized hydrogel formulation. In the microbial limit tests, the optimized hydrogel showed no microbial growth. The developed optimized PVA/PEG hydrogel using freeze-thaw method was swellable, elastic, safe, and it can be considered as a promising new wound dressing formulation.

Matched MeSH terms: Tensile Strength

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