Effect of phosphite loading on the mechanical and fire properties of palm-based polyurethane

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

The Importance of Derivatizing Reagent in Chromatography Applications for Biogenic Amine Detection in Food and Beverages

Biogenic amines (BA) are chemical compounds formed in foods that contain protein, allowing the foods to undergo a bacterial degradation process. Biogenic amines are labeled as toxic food because its consumption exceeding the FDA regulation (50 mg/kg) can be harmful to humans. Some countries also have regulations that prohibit the consumption of biogenic amines in high concentrations, especially histamine. The chromatography methods generally applied by researchers are liquid chromatography (LC) and gas chromatography (GC), where the use of a derivatization reagent is necessary to increase their sensitivity. This review is based on past and present studies about biogenic amine detection related to food samples. The rationale of this study is also to provide data on the comparison of the analytical approaches between LC and GC methods. Furthermore, the various approaches of biogenic amine determination and the most applied analytical methods have been reviewed

Properties of Structural Lightweight Concrete Filled with Palm-Based Polyurethane

Four experiments were conducted to characterize the properties of palm-based polyurethane (PU) foam in lightweight concrete. The PU foam was synthesized from palm kernel oil-based polyol reacted with 2, 4-methylene diphenyl diisocyanate. Polyurethane as lightweight aggregate was mixed with ordinary cement, sand, and water to form lightweight concrete. The microstructure of PU aggregate can be accessed from optical micrographs. Density, compressive strength, distribution of fine aggregate, and the interfacial zone were also investigated. The result showed that palm-based lightweight concrete has excellent compressive strength (17.5 MPa), and fulfilled the minimum strength requirement for structural concrete. Palm-based lightweight concrete with 0.6 w/c ratio and 3% w/w PU system achieved 1770 kg/m3 presented uniform dispersion of aggregate and excellent mechanical bonding

Polyurethane modified screen – printed electrode for the electrochemical detection of histamine in fish

Histamine needs to be determined because of its toxicity. Histamine is commonly determined using chromatography, where not only that the instrument is expensive, the process is very tedious and require an expert. A sensor was developed using palm-based polyurethane as an electro-sensor substrate. Palm-based polyurethane (PU) was produced via condensation polymerization between palm kernel oil-based monoester polyol (PKOp) and 4,4'- diphenylmethane diisocyanate (MDI). PU offers high porosity and capability to attach onto screen–printed electrode (SPE) sturdily without being disintegrated. PU–SPE adsorbed histamine onto its pores, before being oxidized. The oxidation process was detected using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Histamine was oxidized electrochemically at +0.31 V (vs. Ag/AgCl, 1 mol·L-1, pH 7.5). Differential pulse voltemmetric approach were used in order to get a satisfactory response, thus the histamine concentration was made in the range from 1 × 10-4 to 1 mmol·L-1. A good sensitivity of 0.1 mmol·L-1 was attained with 3.07 % during intraday and 9.55 % during interday. The detection and quantification limits of histamine acquired at 0.17 mmol·L-1 and 0.53 mmol·L-1, respectively. A wide variety of interfering compounds were also examined in order to establish their effect, if any, on the determination of histamine at the PU modified electrode. The sensor showed an excellent anti – interference property towards the other amines. The developed chemical sensor using PU – SPE has a good potential to determine histamine level in mackerel (Rastrelliger Brachysoma) owing to its simplicity and reproducibility

The Evolution of Sensing Device for the Detection of Histamine and other Biogenic Amines

This paper reviewed the progressive trend in the sensing of biogenic amine such as histamine. A sensor was developed where this sensor is using palm-based polyurethane as an electro-sensor substrate. Palm based polyurethane (PU) was produced via condensation polymerization between palm kernel oil-based monoester polyol (PKOp)and 4,4’-diphenylmethane diisocyanate (MDI). PU is used in this study due to its porosity and its capability to attach onto screen – printed electrode (SPE) sturdily without disintegrate. PU – SPE absorbed histamine inside its pores so histamine can undergo the oxidation process. The oxidation process was detected using cyclic voltammetry (CV) and differential pulse voltammetry (DPV)

Chemistry Outreach Program and its Impact on Secondary School Students

AbstractChemistry is one of the most difficult subjects and usually feared by the students in elementary schools. Some of the students in Malaysia, especially in the rural area, they memorized experiments and the theories without really understand the beauty of chemistry. They also believed that the chemistry experiment can only be done in the laboratory equipped with a huge fume hood since all of the experiments are dangerous, explosive and costly. Chemistry outreach program held by a team from Universiti Kebangsaan Malaysia was meant to change the perspective of the elementary students towards chemistry and to develop their interest in exploring the beauty of chemistry. The program took place in Perlis as part of the Science on Wheels Program organized by National Science Centre. Few experiments using chemicals which can be found in daily life were first demonstrated and explained. Then the students were given chances to try on their own. They were also asked to relate what they had learned from the experiments to the phenomenon that occurred in the world. Survey on knowing their interest in chemistry before and after the experiments was given and analyzed. The results showed that the level of liking chemistry and choosing chemistry as one of the career option depended mainly on the exposure towards chemistry. The result showed that 80% of the students were interested in chemistry after they performed the experiments compared to 72% who were interested in the chemistry subject taught in school prior to the experiment. The 8% increment was possibly a reflection of the effective learning through experiment. Overall, 58% of students were interested to choose chemistry as their future career and suprisingly it was not depended on the background of the family. The chemistry outreach program really gave the impact on the elementary students and reached their hearts and should be continued from time to time to attract students to science and technology

Study of Histamine Detection using Liquid Chromatography and Gas Chromatography

Histamine is a heterocyclic amine shaped by decarboxylation of the histidine. It is a compound that lack chromophore and involatile. However, the detection of histamine is imperative due to the characteristic of histamine has given several disadvantages in food industry. This paper describes methods for histamine detection by employing high performance liquid chromatography and gas chromatography. The derivatization techniques required for both methods in order to increase the sensitivity of chromatography analysis. Two derivatizing agents were applied in this study such as 9-flourenilmethyl chloroformate (FMOC – Cl) for HPLC analysis whereas for GC analysis a N,O-bis (trimethylsilyl)acetamide (BSA) was used. Method validation was in accordance to Commission Decision 657/2002/CE. The validation of specificity, linearity, precision, accuracy, detection limit and quantitation limit results indicate that the methods were acceptable. The linear range for both methods were at 0.16 – 5.00 µg∙mL-1 . The determination of histamine using GC showed the superiority of this instrument compared to HPLC. Method applicability was also checked on real sample namely mackerel in order to acquire a satisfactory recovery for both methods

Physical and Mechanical Properties of Palm Kernel Oil-Based Polyester Polyurethane/Multi-Walled Carbon Nanotube Composites

In this study, polyurethane (PU) films from palm kernel oil-based polyester (PKO-p) incorporated multi-walled carbon nanotubes (MWNTs) are prepared via a evaporative casting method. Nanoparticle fluid dispersions containing 0.02%,0.03%, and 0.05% wt. of MWNTs are added into PKO-p based resin and mixed by digital probe sonicator for 30 min followed by mixing with isocyanate to produce PU-MWNTs composite films. The mechanical properties, swelling, water vapour transmission rate (WVTR) and conductivity of the PU-MWNTs composite films are examined. Resultsshow that the toughness (T) or flexibility, the tensile strength (TS), and Young’s modulus (YM) values of PU-MWNTs composite films increase with the increasing concentrations of MWNT. In contrast, the water vapour transmission rate (WVTR) and swelling test of PU-MWNTs composite films decrease with the increase of MWNT concentrations. For conductivity testing, the film with 0.05 wt.% MWNT (PU-5) has the highest conductivity value at 2.19 x 10-9 S cm-1. Insummary, incorporation of MWNTs has improved the mechanical properties of the polyurethane composites films

Radiation dose required for the vulcanization of natural rubber latex via hybrid gamma radiation and peroxide vulcanizations

To enhance the crosslinking of prevulcanized natural rubber latex, combination of Irradiation and peroxide vulcanizations were used. Through this method, hexanediol diacrylate (HDDA) from irradiation vulcanization acted as the main sensitizer, while cumene hydroperoxide (CHPO) from peroxide vulcanization would act as the co-sensitizer. The effects of irradiation doses on the mechanical properties of latex film were investigated. 16 kGy irradiation dose, 2.5 parts perhundred rubber (pphr) of HDDA, 0.1 pphr of CHPO and 2.5 phr of Aquanox LP antioxidant were found to be the optimum conditions for compounding formulation. The rubber film obtained had tensile strength, modulus at 500% and modulus at 700% of 27.7, 3.5 and 12.4 MPa respectively, which is more than 21% increment compared to control film. Besides, the crosslink percentage of the rubber film showed 7 % increment from 90.7% to 97.7%