Displaying publications 1 - 20 of 72 in total

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  1. Wong YC, Mahyuddin N, Aminuddin AMR
    Waste Manag, 2020 Dec;118:402-415.
    PMID: 32947219 DOI: 10.1016/j.wasman.2020.08.036
    Recycling automotive waste has increasingly become an alternative solution towards producing sustainable materials given the rising issue of raw material shortages and waste management challenges at global level. The improper end-of-life vehicle (ELV) waste management poses detrimental impacts on the environment. This paper proposes a novel method to develop thermal insulation sandwich panels using ELV waste, motivated by the critical needs of creating high-performance thermal insulation for buildings. Six sandwich panels (P1-P6) of different weight and ratio of shredded ELV particles were manufactured. The sandwich panels structure was made of three layers: a core, and a glass face sheet bonded to each side. The core structure composed of Polycarbonate (PC) from headlamp lenses and polyurethane (PU) from seat, bonded using resin casting approach. Thermal conductivity of the samples was measured using guarded hot-plate apparatus. Results corroborated that thermal conductivity of ELV-based sandwich panels reduced remarkably compared to panel without ELVs, recorded at 15.51% reduction. Composition gives the best thermal performance was made of mixed ELV core materials of ratio 50%PC:50%PU, it has a thermal conductivity value of 0.1776 W/mK. The transparency data were obtained using Haze-gard plus haze meter. The best luminous transmittance value was exhibited by P2 (100% PC), 67.47%. The best clarity value and haze value were shown by P6 (25% PC: 75% PU), 55.13% and 52.6% respectively. ELV waste can be recycled to develop useful sustainable thermal insulation to improve thermal and optical transparency performance of buildings as a substitute for conventional materials which have a relevance for future façade concepts.
    Matched MeSH terms: Polyurethanes
  2. Agi A, Junin R, Alqatta AYM, Gbadamosi A, Yahya A, Abbas A
    Ultrason Sonochem, 2019 Mar;51:214-222.
    PMID: 30401623 DOI: 10.1016/j.ultsonch.2018.10.023
    Ultrafiltration has been proven to be very effective in the treatment of oil-in-water emulsions, since no chemical additives are required. However, ultrafiltration has its limitations, the main limits are concentration polarization resulting to permeate flux decline with time. Adsorption, accumulation of oil and particles on the membrane surface which causes fouling of the membrane. Studies have shown that the ultrasonic is effective in cleaning of fouled membrane and enhancing membrane filtration performance. But the effectiveness also, depends on the selection of appropriate membrane material, membrane geometry, ultrasonic module design, operational and processing condition. In this study, a hollow and flat-sheet polyurethane (PU) membranes synthesized with different additives and solvent were used and their performance evaluated with oil-in-water emulsion. The steady-state permeate flux and the rejection of oil in percentage (%) at two different modes were determined. A dry/wet spinning technique was used to fabricate the flat-sheet and hollow fibre membrane (HFMs) using Polyethersulfone (PES) polymer base, Polyvinylpyrrolidone (PVP) additive and N, N-Dimethylacetamide (DMAc) solvent. Ultrasonic assisted cross-flow ultrafiltration module was built to avoid loss of ultrasonic to the surrounding. The polyurethane (PU) was synthesized by polymerization and sulphonation to have an anionic group (-OH; -COOH; and -SO3H) on the membrane surface. Changes in morphological properties of the membrane had a significant effect on the permeate flow rate and oil removal. Generation of cavitation and Brownian motion by the ultrasonic were the dominant mechanisms responsible for ultrafiltration by cracking the cake layers and reducing concentration polarization at the membrane surface. The percentage of oil after ultrafiltration process with ultrasonic is about 90% compared to 49% without ultrasonic. Ultrasonic is effective in enhancing the membrane permeate flux and controlling membrane fouling.
    Matched MeSH terms: Polyurethanes
  3. Kannan RY, Sales KM, Salacinski HJ, Butler PE, Seifalian AM
    Med J Malaysia, 2004 May;59 Suppl B:107-8.
    PMID: 15468841
    Matched MeSH terms: Polyurethanes*
  4. Kannan RY, Sales KM, Salacinski HJ, Butler PE, Seifalian AM
    Med J Malaysia, 2004 May;59 Suppl B:99-100.
    PMID: 15468837
    Matched MeSH terms: Polyurethanes/pharmacology*
  5. Darmawati MY, Ismarul N, Fuad Y, Fazan F
    Med J Malaysia, 2004 May;59 Suppl B:27-8.
    PMID: 15468802
    Linear polymers have been commonly used as dental composite. However the aim of this work is to use hyperbranched polymer in an attempt to produce dental composite. The reason is because the dendritic molecules have shown low viscosity at higher molecular weight compared to the linear counterparts. Therefore, this work attempts to substitute the linear polymer with as much of hyperbranched polymer in the dental composite that would pass the required ISO 4049:1998(E) "Dentistry - Resin-based filling material". Several formulations of dental composites were used, i.e. combinations of linear-linear and linear-hyperbranched polymers for comparison. Following this, physical and mechanical characterisation were conducted based on the ISO standards such as water sorption and water solubility. Other characterisation such as polymerisation shrinkage and Vickers hardness were also evaluated. It was found that different types of resins give different physical and mechanical properties. The maximum achievable hyperbranched polymer, which passes the required ISO standard, that can be incorporated in the linear polymer to form dental composite is 43% wt.
    Matched MeSH terms: Polyurethanes/standards*
  6. Memon MS, Yunus N, Razak AA
    Int J Prosthodont, 2001 May-Jun;14(3):214-8.
    PMID: 11484567
    PURPOSE: The impact strength and the flexural properties of denture base materials are of importance in predicting their clinical performance upon sudden loading. This study compares the impact and transverse strengths and the flexural modulus of three denture base polymers.
    MATERIALS AND METHODS: The investigation included a relatively new microwave-polymerized polyurethane-based denture material processed by an injection-molding technique, a conventional microwave-polymerized denture material, and a heat-polymerized compression-molded poly(methyl methacrylate) (PMMA) denture material. Impact strength was determined using a Charpy-type impact tester. The transverse strength and the flexural modulus were assessed with a three-point bending test. The results were subjected to statistical analysis using a one-way analysis of variance and the Scheffé test for comparison.
    RESULTS: The impact strength of the microwave-polymerized injection-molded polymer was 6.3 kl/m2, while its flexural strength was 66.2 MPa. These values were lower than those shown by the two compression-molded PMMA-based polymers. The differences were statistically significant. The flexural modulus of the new denture material was 2,832 MPa, which was higher than the conventional heat-polymerized polymer but was comparable to the other microwave-polymerized PMMA-based polymer. The difference in the flexural modulus was statistically significant.
    CONCLUSION: In terms of the impact and flexural strengths, the new microwave-polymerized, injection-molded, polyurethane-based polymer offered no advantage over the existing heat- and microwave-polymerized PMMA-based denture base polymers. However, it has a rigidity comparable to that of the microwave-polymerized PMMA polymer.
    Matched MeSH terms: Polyurethanes/radiation effects; Polyurethanes/chemistry
  7. Lai NM, Taylor JE, Tan K, Choo YM, Ahmad Kamar A, Muhamad NA
    Cochrane Database Syst Rev, 2016 Mar 23;3:CD011082.
    PMID: 27007217 DOI: 10.1002/14651858.CD011082.pub2
    BACKGROUND: Central venous catheters (CVCs) provide secured venous access in neonates. Antimicrobial dressings applied over the CVC sites have been proposed to reduce catheter-related blood stream infection (CRBSI) by decreasing colonisation. However, there may be concerns on the local and systemic adverse effects of these dressings in neonates.

    OBJECTIVES: We assessed the effectiveness and safety of antimicrobial (antiseptic or antibiotic) dressings in reducing CVC-related infections in newborn infants. Had there been relevant data, we would have evaluated the effects of antimicrobial dressings in different subgroups, including infants who received different types of CVCs, infants who required CVC for different durations, infants with CVCs with and without other antimicrobial modifications, and infants who received an antimicrobial dressing with and without a clearly defined co-intervention.

    SEARCH METHODS: We used the standard search strategy of the Cochrane Neonatal Review Group (CNRG). We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2015, Issue 9), MEDLINE (PubMed), EMBASE (EBCHOST), CINAHL and references cited in our short-listed articles using keywords and MeSH headings, up to September 2015.

    SELECTION CRITERIA: We included randomised controlled trials that compared an antimicrobial CVC dressing against no dressing or another dressing in newborn infants.

    DATA COLLECTION AND ANALYSIS: We extracted data using the standard methods of the CNRG. Two review authors independently assessed the eligibility and risk of bias of the retrieved records. We expressed our results using risk difference (RD) and risk ratio (RR) with 95% confidence intervals (CIs).

    MAIN RESULTS: Out of 173 articles screened, three studies were included. There were two comparisons: chlorhexidine dressing following alcohol cleansing versus polyurethane dressing following povidone-iodine cleansing (one study); and silver-alginate patch versus control (two studies). A total of 855 infants from level III neonatal intensive care units (NICUs) were evaluated, 705 of whom were from a single study. All studies were at high risk of bias for blinding of care personnel or unclear risk of bias for blinding of outcome assessors. There was moderate-quality evidence for all major outcomes.The single study comparing chlorhexidine dressing/alcohol cleansing against polyurethane dressing/povidone-iodine cleansing showed no significant difference in the risk of CRBSI (RR 1.18, 95% CI 0.53 to 2.65; RD 0.01, 95% CI -0.02 to 0.03; 655 infants, moderate-quality evidence) and sepsis without a source (RR 1.06, 95% CI 0.75 to 1.52; RD 0.01, 95% CI -0.04 to 0.06; 705 infants, moderate-quality evidence). There was a significant reduction in the risk of catheter colonisation favouring chlorhexidine dressing/alcohol cleansing group (RR 0.62, 95% CI 0.45 to 0.86; RD -0.09, 95% CI -0.15 to -0.03; number needed to treat for an additional beneficial outcome (NNTB) 11, 95% CI 7 to 33; 655 infants, moderate-quality evidence). However, infants in the chlorhexidine dressing/alcohol cleansing group were significantly more likely to develop contact dermatitis, with 19 infants in the chlorhexidine dressing/alcohol cleansing group having developed contact dermatitis compared to none in the polyurethane dressing/povidone-iodine cleansing group (RR 43.06, 95% CI 2.61 to 710.44; RD 0.06, 95% CI 0.03 to 0.08; number needed to treat for an additional harmful outcome (NNTH) 17, 95% CI 13 to 33; 705 infants, moderate-quality evidence). The roles of chlorhexidine dressing in the outcomes reported were unclear, as the two assigned groups received different co-interventions in the form of different skin cleansing agents prior to catheter insertion and during each dressing change.In the other comparison, silver-alginate patch versus control, the data for CRBSI were analysed separately in two subgroups as the two included studies reported the outcome using different denominators: one using infants and another using catheters. There were no significant differences between infants who received silver-alginate patch against infants who received standard line dressing in CRBSI, whether expressed as the number of infants (RR 0.50, 95% CI 0.14 to 1.78; RD -0.12, 95% CI -0.33 to 0.09; 1 study, 50 participants, moderate-quality evidence) or as the number of catheters (RR 0.72, 95% CI 0.27 to 1.89; RD -0.05, 95% CI -0.20 to 0.10; 1 study, 118 participants, moderate-quality evidence). There was also no significant difference between the two groups in mortality (RR 0.55, 95% CI 0.15 to 2.05; RD -0.04, 95% CI -0.13 to 0.05; two studies, 150 infants, I² = 0%, moderate-quality evidence). No adverse skin reaction was recorded in either group.

    AUTHORS' CONCLUSIONS: Based on moderate-quality evidence, chlorhexidine dressing/alcohol skin cleansing reduced catheter colonisation, but made no significant difference in major outcomes like sepsis and CRBSI compared to polyurethane dressing/povidone-iodine cleansing. Chlorhexidine dressing/alcohol cleansing posed a substantial risk of contact dermatitis in preterm infants, although it was unclear whether this was contributed mainly by the dressing material or the cleansing agent. While silver-alginate patch appeared safe, evidence is still insufficient for a recommendation in practice. Future research that evaluates antimicrobial dressing should ensure blinding of caregivers and outcome assessors and ensure that all participants receive the same co-interventions, such as the skin cleansing agent. Major outcomes like sepsis, CRBSI and mortality should be assessed in infants of different gestation and birth weight.

    Matched MeSH terms: Polyurethanes
  8. Rida Tajau, Mohd hilmi Mahmood, Mek Zah Salleh, Khairul Zaman Mohd dahlan, Rosley Che ismail, Sharilla Muhammad Faisal, et al.
    Sains Malaysiana, 2013;42:459-467.
    In recent years, there are growing trends in using palm oil as raw materials in radiation curable resins production. In this study, the acrylated palm oil resins i.e. the EPOLA (epoxidized palm oil acrylate) and the POBUA (palm oil based urethane acrylate) were synthesized using two different systems, i.e. the 25 liter pilot scale reactor synthesis system and the 2 liter (L) laboratory scale reactor synthesis system through chemical processes known as acrylation and isocyanation. In this
    paper, the property of the acrylated resins which were produced by these two systems were evaluated and compared between each other. Their properties were characterized using the Fourier transform infrared (FTIR) spectrophotometer for functional group identification; the gel permeation chromatography (GPC) for molecular weight (Mw) determination, the Brookfield viscometer for viscosity measurements, the acid values (AV) and the oxirane oxygen contents (OOC) analysis. As a result, the production process for both the 2 L and 25 L reactor system were found to be time consuming and the main advantages for the 25 L reactor was its higher productivity as compared with the 2 L reactor system with the same synthesis process parameters i.e. the temperatures and the experimental methods. Besides that, the 25 L reactor synthesis
    process was found to be safe, easy to control and served unpolluted process to the environments. The final products, the acrylated palm oil resins were formulated into ultraviolet (UV) curable compounds before subjecting them under UVirradiation. As a result, the UV-curable palm oil resins showed potential uses as pressure sensitive adhesives, printing inks including overprint varnishes (OPV) and coatings.
    Matched MeSH terms: Polyurethanes
  9. Khairiah Badri, Amamer Musbah Redwan
    Fire-retarding polyurethane (PU) composite was produced by adding 2,4-ditert-butylphenyl phosphite (FR) to palm-based monoester resin with loading percentage of 0, 2, 4, and 6 wt%. The Shore D hardness index increased marginally with increasing FR content. However, the impact and flexural strengths decreased with increasing FR loading attributed to the weak interfacial bonding between FR and PU matrix. The fire test indicated lowering of burning rate (from 5.30 mm.s-1 to 2.80 mm.s-1) as the loading percentage of FR increased. The combustion enthalpy of the composites also decreased with higher loading percentage of FR.
    Matched MeSH terms: Polyurethanes
  10. Huang C, Lou C, Chuang Y, Lin J, Liu C, Yu Z
    Sains Malaysiana, 2015;44:1757-1763.
    Following rapid technological and industrial development, factories have been equipped with a great deal of machines.
    The blend of industrial and residential areas in turn resulted in many environmental problems. In particular, machine
    operation causes noise pollution that easily causes physiological and psychological discomfort for the human body thus
    makes noise abatement a crucial and urgent issue. In this study, vermiculite functional fillers were added to polyurethane
    (PU) foam mixtures in order to form sound absorbent PU foams. The correlations between the contents of functional fillers
    and the sound absorption of flexible and rigid PU foams were then examined. The optimal PU foams were combined with
    PET/carbon fiber matrices in order to yield the electromagnetic shielding effectiveness. The sound absorption, noise
    reduction coefficient (NRC), electromagnetic shielding effectiveness and resilience rate of the composite boards were
    finally evaluated. The test results indicated that rigid PU foam composites can reach a sound absorption coefficient of
    0.8 while the flexible PU foam composites have higher mechanical properties.
    Matched MeSH terms: Polyurethanes
  11. Nor Rabbi’atul ‘Adawiyah Norzali, Khairiah Badri, Mohd Zaki Nuawi
    The effect of adding aluminum hydroxide (ATH) in the palm-based polyurethane hybrid composite was studied. The compression stress and modulus, thermal conductivity and acoustic property were determined. The hybrid composite was prepared by adding 10 wt% of oil palm empty fruit bunch fibre (EFB) followed by ATH at varying amount of 2, 4 and 6 wt% of the overall mass of the resin. The compression stress and modulus gave the highest values of 575 kPa and 2301 kPa, respectively at 2 wt% ATH. At 4 wt% ATH, the compression stress and modulus decreased to 431 kPa and 1659 kPa, respectively and further decreased at 6 wt% ATH to 339 kPa and 1468 kPa respectively. The k-value increased with the increment of the ATH loading exhibited a poor thermal conductivity. Sound absorption analysis indicated that the absorption coefficient was higher at higher frequency (4000 Hz) for all samples with PU-EFB/ATH with 4% ATH showed the highest absorption coefficient.
    Matched MeSH terms: Polyurethanes
  12. Liow CH, Sahrim Ahmad, Khairiah Badri
    In-situ polymerization method was used to prepare palm-based polyurethane (PU) composites loading with 15 wt% magnetite (Fe3O4), polyaniline (PANI) and Fe3O4 coated with PANI labeled as PU15, PP and PPM, respectively. FTIR spectroscopy analysis indicated a shift in the carbonyl, C=O and NH in PP. The shift of the peak indicated that there was hydrogen bonding between the C=O (proton acceptor) of urethane with NH (proton-donator) of PANI. PPM gave the highest impact and flexural strengths at 4875 kJ/ m2 and 42 MPa, respectively but with the lowest flexural modulus (1050 MPa). Two-stage degradation behavior was observed in the TGA thermogram.
    Matched MeSH terms: Polyurethanes
  13. Nor Rabbi’atul ‘Adawiyah Norzali, Khairiah Badri, Mohd Zaki Nuawi
    Sains Malaysiana, 2011;40:1179-1186.
    Effects of aluminium hydroxide (ATH) addition on the properties of palm-based polyurethane composites were investigated. The hybrid composites were prepared by mixing 10 wt% of oil palm empty fruit bunch fiber (EFB) with ATH at varying amount of 2, 4 and 6 wt% of the overall mass of the resin. The compression stress and modulus gave the highest values of 575 and 2301 kPa, respectively at 2 wt% loading of ATH. The compression stress and modulus decreased drastically at 4 wt% (431 kPa and 1659 kPa, respectively) and further decreased at 6 wt% ATH (339 and 1468 kPa, respectively). However, the burning rate is inversely proportional to the loading percentage where the highest burning rate was observed at 2 wt% ATH. Sound absorption analysis indicated a large absorption coefficient at high frequency (4000 Hz) for all samples. The highest absorption coefficient was obtained from PU-EFB/ATH with 4 wt% ATH.
    Matched MeSH terms: Polyurethanes
  14. Azlisham NAF, Johari Y, Mohamad D, Yhaya MF, Mahmood Z
    Proc Inst Mech Eng H, 2023 Dec;237(12):1339-1347.
    PMID: 38014749 DOI: 10.1177/09544119231208222
    This study evaluated the use of urethane dimethacrylate (UDMA) as a base monomer to prepare the newly developed flowable composite (FC) using nanohybrid silica derived from rice husk in comparison to bisphenol A-glycidyl methacrylate (Bis-GMA) on the degree of conversion and physicomechanical properties. The different loadings of base monomer to diluent monomer were used at the ratio of 40:60, 50:50, and 60:40. The bonding analysis confirmed the presence of nanohybrid silica in the newly developed FC. Independent t-test revealed a statistically significant increase in the degree of conversion, depth of cure and Vickers hardness of the UDMA-based FC, while surface roughness showed comparable results between the two base monomers. In conclusion, UDMA-based FC demonstrated superior performance with 60%-65% conversions, a significantly higher depth of cure exceeding 1 mm which complies with the Internal Standard of Organization 4049 (ISO 4049), and a substantial increase in Vickers hardness numbers compared to Bis-GMA-based FC, making UDMA a suitable alternative to Bis-GMA as a base monomer in the formulation of this newly developed FC derived from rice husk.
    Matched MeSH terms: Polyurethanes
  15. Mani MP, Jaganathan SK, Supriyanto E
    Polymers (Basel), 2019 Aug 08;11(8).
    PMID: 31398835 DOI: 10.3390/polym11081323
    Scaffolds supplemented with naturally derived materials seem to be a good choice in bone tissue engineering. This study aims to develop polyurethane (PU) nanofibers added with ylang ylang (YY) and zinc nitrate (ZnNO3) using the electrospinning method. Field emission scanning electron microscopy (FESEM) images showed that the diameter of the PU nanofibers (869 ± 122 nm) was reduced with the addition of YY and ZnNO3 (PU/YY-467 ± 132 nm and PU/YY/ZnNO3-290 ± 163 nm). Fourier transform infrared (FTIR), a thermal gravimetric analysis (TGA) and an X-ray diffraction (XRD) analysis confirmed the interactions between PU with YY and ZnNO3. In addition, a thermal gravimetric analysis (TGA) study revealed the improved thermal stability for PU/YY and a slight reduction in the thermal stability for PU/YY/ZnNO3. A tensile test indicated that the addition of YY and ZnNO3 (PU/YY-12.32 MPa and PU/YY/ZnNO3-14.90 MPa) improved the mechanical properties of the pristine PU (6.83 MPa). The electrospun PU/YY (524 nm) and PU/YY/ZnNO3 (284 nm) showed a reduced surface roughness when compared with the pristine PU (776 nm) as depicted in the atomic force microscopy (AFM) analysis. The addition of YY and ZnNO3 improved the anticoagulant and biocompatibility nature of the pristine PU. Furthermore, the bone mineralization study depicted the improved calcium deposition in the fabricated composites (PU/YY-7.919% and PU/YY/ZnNO3-10.150%) compared to the pristine PU (5.323%). Hence, the developed composites with desirable physico-chemical properties, biocompatibility and calcium deposition can serve as plausible candidates for bone tissue engineering.
    Matched MeSH terms: Polyurethanes
  16. Ibrahim F, Mohan D, Sajab MS, Bakarudin SB, Kaco H
    Polymers (Basel), 2019 Sep 23;11(10).
    PMID: 31547544 DOI: 10.3390/polym11101544
    In this study, lignin has been extracted from oil palm empty fruit bunch (EFB) fibers via an organosolv process. The organosolv lignin obtained was defined by the presence of hydroxyl-containing molecules, such as guaiacyl and syringyl, and by the presence of phenolic molecules in lignin. Subsequently, the extracted organosolv lignin and graphene nanoplatelets (GNP) were utilized as filler and reinforcement in photo-curable polyurethane (PU), which is used in stereolithography 3D printing. The compatibility as well as the characteristic and structural changes of the composite were identified through the mechanical properties of the 3D-printed composites. Furthermore, the tensile strength of the composited lignin and graphene shows significant improvement as high as 27%. The hardness of the photo-curable PU composites measured by nanoindentation exhibited an enormous improvement for 0.6% of lignin-graphene at 92.49 MPa with 238% increment when compared with unmodified PU.
    Matched MeSH terms: Polyurethanes
  17. Saalah S, Abdullah LC, Aung MM, Salleh MZ, Awang Biak DR, Basri M, et al.
    Polymers (Basel), 2021 Mar 05;13(5).
    PMID: 33807622 DOI: 10.3390/polym13050795
    Nowadays, there is a significant trend away from solvent-based polyurethane systems towards waterborne polyurethane dispersions due to government regulations requiring manufacturers to lower total volatile organic compounds, as well as consumer preference for more environmentally friendly products. In this work, a renewable vegetable oil-based polyol derived from jatropha oil was polymerized with isophorone diisocyanate and dimethylol propionic acid to produce anionic waterborne polyurethane dispersion. Free standing films with up to 62 wt.% bio-based content were successfully produced after evaporation of water from the jatropha oil-based waterborne polyurethane (JPU) dispersion, which indicated good film formation. The chemical and thermo-mechanical properties of the JPU films were characterized. By increasing the OH numbers of polyol from 161 mgKOH/g to 217 mgKOH/g, the crosslinking density of the JPU was significantly increased, which lead to a better storage modulus and improved hydrophobicity. Overall, JPU produced from polyol having OH number of 217 mgKOH/g appears to be a promising product for application as a binder for wood and decorative coatings.
    Matched MeSH terms: Polyurethanes
  18. Fallahiarezoudar E, Ahmadipourroudposht M, Yusof NM, Idris A, Ngadiman NHA
    Polymers (Basel), 2017 Nov 06;9(11).
    PMID: 30965883 DOI: 10.3390/polym9110584
    Valvular dysfunction as the prominent reason of heart failure may causes morbidity and mortality around the world. The inability of human body to regenerate the defected heart valves necessitates the development of the artificial prosthesis to be replaced. Besides, the lack of capacity to grow, repair or remodel of an artificial valves and biological difficulty such as infection or inflammation make the development of tissue engineering heart valve (TEHV) concept. This research presented the use of compound of poly-l-lactic acid (PLLA), thermoplastic polyurethane (TPU) and maghemite nanoparticle (γ-Fe₂O₃) as the potential biomaterials to develop three-dimensional (3D) aortic heart valve scaffold. Electrospinning was used for fabricating the 3D scaffold. The steepest ascent followed by the response surface methodology was used to optimize the electrospinning parameters involved in terms of elastic modulus. The structural and porosity properties of fabricated scaffold were characterized using FE-SEM and liquid displacement technique, respectively. The 3D scaffold was then seeded with aortic smooth muscle cells (AOSMCs) and biological behavior in terms of cell attachment and proliferation during 34 days of incubation was characterized using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and confocal laser microscopy. Furthermore, the mechanical properties in terms of elastic modulus and stiffness were investigated after cell seeding through macro-indentation test. The analysis indicated the formation of ultrafine quality of nanofibers with diameter distribution of 178 ± 45 nm and 90.72% porosity. In terms of cell proliferation, the results exhibited desirable proliferation (109.32 ± 3.22% compared to the control) of cells over the 3D scaffold in 34 days of incubation. The elastic modulus and stiffness index after cell seeding were founded to be 22.78 ± 2.12 MPa and 1490.9 ± 12 Nmm², respectively. Overall, the fabricated 3D scaffold exhibits desirable structural, biological and mechanical properties and has the potential to be used in vivo.
    Matched MeSH terms: Polyurethanes
  19. Teo KT, Hassan A, Gan SN
    Polymers (Basel), 2018 Dec 11;10(12).
    PMID: 30961299 DOI: 10.3390/polym10121374
    Palm fatty acid distillate (PFAD), is a by-product of the crude palm oil refining process. It comprises mainly of free fatty acids-around 45% palmitic and 33% oleic acids-as the major components. Ultra-violet (UV) curable urethane acrylate (UA) oligomers could be synthesized from PFAD, by the following procedure. A hydroxyl terminated macromer was first prepared by reacting PFAD with a mixture of isophthalic acid, phthalic anhydride, neopentagylcol (NPG), and pentaerythritol. The macromer was then reacted with 2-hydroxylethylacrylate (2HEA) and toluene diisocynate (TDI) to generate a resin, containing acrylate side chains for UV curable application. A series of UA resins were prepared by using 15, 25, 45, 55, and 70% of PFAD, respectively. The UA resin has Mw in the range of 3,200 to 27,000. They could be cured by UV irradiation at an intensity of 225 mW/cm². Glass transition temperature (Tg) of the cured film was measured by differential scanning calorimeter (DSC), and hardness of the film was determined by a pendulum hardness tester, according to American Society for Testing and Materials (ASTM)4366. The resins were used in a wood-coating application. All of the cured films showed good adhesion, hardness, and chemical resistance except for the one using the 70% PFAD, which did not cure properly.
    Matched MeSH terms: Polyurethanes
  20. Jaganathan SK, Mani MP, Khudzari AZM
    Polymers (Basel), 2019 Apr 01;11(4).
    PMID: 30960571 DOI: 10.3390/polym11040586
    The ultimate goal in tissue engineering is to fabricate a scaffold which could mimic the native tissue structure. In this work, the physicochemical and biocompatibility properties of electrospun composites based on polyurethane (PU) with added pepper mint (PM) oil and copper sulphate (CuSO₄) were investigated. Field Emission Electron microscope (FESEM) study depicted the increase in mean fiber diameter for PU/PM and decrease in fiber diameter for PU/PM/CuSO₄ compared to the pristine PU. Fourier transform infrared spectroscopy (FTIR) analysis revealed the formation of a hydrogen bond for the fabricated composites as identified by an alteration in PU peak intensity. Contact angle analysis presented the hydrophobic nature of pristine PU and PU/PM while the PU/PM/CuSO₄ showed hydrophilic behavior. Atomic force microscopy (AFM) analysis revealed the increase in the surface roughness for the PU/PM while PU/PM/CuSO₄ showed a decrease in surface roughness compared to the pristine PU. Blood compatibility studies showed improved blood clotting time and less toxic behavior for the developed composites than the pristine PU. Finally, the cell viability of the fabricated composite was higher than the pristine PU as indicated in the MTS assay. Hence, the fabricated wound dressing composite based on PU with added PM and CuSO₄ rendered a better physicochemical and biocompatible nature, making it suitable for wound healing applications.
    Matched MeSH terms: Polyurethanes
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