Multiwall carbon nanotube (CNT)-filled high density polyethylene (HDPE) nanocomposites were prepared by extrusion and considered for their suitability in the offshore sheathing applications. Transmission electron microscopy was conducted to analyse dispersion after bulk extrusion. Monolithic and nanocomposite samples were subjected to accelerated weathering and photodegradation (carbonyl and vinyl indices) characterisations, which consisted of heat, moisture (seawater) and UV light, intended to imitate the offshore conditions. The effects of accelerated weathering on mechanical properties (tensile strength and elastic modulus) of the nanocomposites were analysed. CNT addition in HDPE produced environmentally resilient nanocomposites with improved mechanical properties. The energy utilised to extrude nanocomposites was also less than the energy used to extrude monolithic HDPE samples. The results support the mass substitution of CNT-filled HDPE nanocomposites in high-end offshore applications.
To understand the variations in the decomposability of tropical peat soil following deforestation for an oil palm plantation, a field incubation experiment was conducted in Sarawak, Malaysia. Peat soils collected from three types of primary forest, namely Mixed Peat Swamp (MPS; Gonystylus-Dactylocladus-Neoscrotechinia association), Alan Batu (ABt; Shorea albida-Gonstylus-Strenonurus association), and Alan Bunga (ABg; Shorea albida association), were packed in polyvinyl chloride pipes and installed in an oil palm plantation. Carbon dioxide (CO2) and methane (CH4) fluxes from soil were monthly measured for 3years. Environmental variables including soil temperature, soil moisture content, and groundwater table were also monitored. The pH, loss on ignition, and total carbon (C) content were similar among the three soils, while total N content was larger in the MPS than in the ABg soils. Based on13C nuclear magnetic resonance (NMR) spectroscopy, C composition of the MPS and ABg soils was characterized by the largest proportion of C present as alkyl C and O-alkyl C, respectively. The C composition of the ABt soil was intermediate between the MPS and ABg soils. The CO2fluxes from the three soils ranged from 78 to 625mgCm-2h-1with a negative correlation to groundwater level. The CH4fluxes ranged from -67 to 653μgCm-2h-1. Both total CO2and CH4fluxes were larger in the order ABg>ABt>MPS (P<0.05). Annual rate of peat decomposition as was estimated from cumulative C loss differed up to 2 times, and the rate constant in exponential decay model was 0.033y-1for the MPS soil and 0.066y-1for the ABg soil. The field incubation results of the three forest peat soils seem to reflect the difference in the labile organic matter content, represented by polysaccharides.
Capacitive biosensors are an emerging technology revolutionizing wearable sensing systems and personal healthcare devices. They are capable of continuously measuring bioelectrical signals from the human body while utilizing textiles as an insulator. Different textile types have their own unique properties that alter skin-electrode capacitance and the performance of capacitive biosensors. This paper aims to identify the best textile insulator to be used with capacitive biosensors by analysing the characteristics of 6 types of common textile materials (cotton, linen, rayon, nylon, polyester, and PVC-textile) while evaluating their impact on the performance of a capacitive biosensor. A textile-insulated capacitive (TEX-C) biosensor was developed and validated on 3 subjects. Experimental results revealed that higher skin-electrode capacitance of a TEX-C biosensor yields a lower noise floor and better signal quality. Natural fabric such as cotton and linen were the two best insulating materials to integrate with a capacitive biosensor. They yielded the lowest noise floor of 2 mV and achieved consistent electromyography (EMG) signals measurements throughout the performance test.
In this present study, a series of polymer electrolyte thin films were synthesized by incorporating different ratios of lithium triflate (LiCF3SO3) in a low molecular weight polyvinyl chloride (PVC) matrix by the solution casting technique. The incorporation of LiCF3SO3 suppressed the high degree of crystallinity in PVC enabling the system to possess an appreciable ionic conductivity. The ionic conductivity of the samples, with different LiCF3SO3 content, was determined by the aid of ac impedance spectroscopy. The highest ionic conductivity of 4.04 10–9 S cm–1 was identified for the composition of PVC: LiCF3SO3 (75:25). Further understanding of the ionic conductivity mechanism was based on temperature-dependent conductivity data which obeyed Arrhenius theory, indicating that the ionic conductivity enhancement was thermally assisted. The possible dipole-dipole interaction between the chemical constituents was confirmed with changes in cage peak, analysed using Fourier transform infrared spectroscopy.
The aim of this study is to design radon irradiation technique in the field of hematology for an invitro study. In addition, deposit of alpha particles into the human blood surface and its effects on the thrombocytopenia estimated using nuclear track detectors (NTDs). In this technique, amount of radon gas (2210±5.1Bq/m 3 ) collected in a tight PVC container with the appropriate engineering dimension using two sources of radium (5μCi). Blood samples (10 male and 10 female) and CR-39NTDs (40 pieces) are exposed to radon gas at various exposure time. Complete blood test and the computer scanning for each piece of CR-39NTDs before and after exposure has done. The results show that the present technique has a good efficiency (96%) to the invitro exposure of human blood. When the radon gas moved on the surface of blood sample, alpha tracks registered into CR-39NTDs. Thus, this technique improved that the comparative method to evaluate alpha particle density into exposure blood samples is an effective way; this depended on the geometry of design and the sensitivity of CR-39NTDs to track registration. Radon detector version 7 (RAD7) used to make a certain suitability of CR- 39NTDs. Amount of radon concentration losses during the exposure process, in the present work it was variable from 0.41% to 1.4%. Radon concentration effected on the thrombocytopenia; this depended on time of exposure and alpha energy loss into the blood and CR-39 through the atomic displacements. At the time of exposure of 10 minutes, rate of absorption dose was 2.255±0.11μSv (39%), and the platelet (PLT) cont reduced rapidly (high effected on reduce PLT, this makes thrombocytopenia.
Cellulose nanocrystals (CNC) from mengkuang leaves (Pandanus tectorius) were investigated as potential reinforcement
in poly(vinyl chloride) (PVC) matrix. The surface of CNC was modified with silane coupling agent to improve fillermatrix
adhesion. Solution casting method was used to prepare PVC nanocomposites with various amounts of modified
(SCNC) and unmodified (CNC) nanocrystals. Both SCNC and CNC were examined by Fourier transform infrared (FTIR)
spectroscopy and X-ray diffraction (XRD) which showed that surface chemical modification has occurred. An increase
in tensile strength was observed with the addition of SCNC compared to the CNC. However, the elongation at break of the
nanocomposites was found to decrease with the increase of both fillers loading. An increasing trend was observed in the
tensile modulus with the addition of CNC to the PVC matrix, but decreasing with the addition of SCNC. The morphology
of a fractured surface of nanocomposites showed silane modification reduced the number of voids in the structure of
PVC. The observation indicated the adhesion between the fiber and the matrix had improved upon surface modification
of the nanocrystals with silane.
Natural organic and abundant resources biopolymers received more attention due to their low cost, availability and degradability after usage. Cassava skin was used as natural fillers to the polyvinyl alcohol (PVA). Cassava skin/poly vinyl alcohol blends were compounded using melt extrusion twin screw extruder and test samples were prepared using the compression method. Various ratios of cassava skin and glycerol were investigated to identify suitable composition based on the water absorption and tensile properties. The water absorption of the cassava skins/PVA samples increased at higher composition of cassava skin due to their hydrophilic properties but decrease with glycerol content. The strength of the cassava skins/PVA samples increased with the higher composition of cassava skin up to 70 wt% while gradually decreased with the increasing composition of glycerol. The Young modulus increased with glycerol content but decreased with fibre loading up to 70 wt%. Elongation at break decreased with fibre loading and glycerol up to 70 wt% and 30 phr, respectively.
Epoxidized natural rubber/polyvinyl chloride/microcrystalline cellulose (ENR/PVC/MCC) composite membranes were
prepared and used to treat palm oil mill effluent (POME). The loadings of MCC were varied at 0, 5, 10 and 15 w/w%. The
increment of MCC loads has intensified the hydroxyl peak of the membranes in FTIR spectrum, indicating the increase
in membrane hydrophilicity. MCC acted as a pore forming agent since the ENR/PVC/10% MCC gave the highest water
flux and well-distributed pores. After first treatment of POME, the levels of chemical oxygen demand (COD), biochemical
oxygen demand (BOD) and total suspended solid (TSS) were reduced to 99.9%, 70.3%, and 16.9%, respectively. These
data showed that ENR/PVC/MCC membrane has the potential to treat POME.
The development of natural fiber polymer composites is increasing worldwide and in some applications, these composites
are used at outdoor rendering them exposed to ultra-violet (UV) radiation. The paper investigates the degradation behavior
of linear low density polyethylene/poly (vinyl alcohol)/kenaf (LLDPE/PVOH/KNF) composites after exposure to different
natural weathering durations. The composites with KNF loadings of 10, 20 and 40 parts per hundred resin (phr) were
exposed to natural weathering for 3 months and 6 months, respectively. The weathered composites were characterized by
Fourier transform infrared (FTIR) spectroscopy, universal testing machine, field emission scanning electron microscopy
(FESEM) and differential scanning calorimetry (DSC). The FTIR analysis showed an obvious carbonyl peak in composites
after weathering as an evidence of oxidation. The weight loss percentage of composites increased with respect to exposure
duration due to higher absorption of UV irradiation. The tensile properties of weathered composites were lower than
that of control composites and these properties also decreased with increasing exposure duration. FESEM micrographs
illustrated that composites with longer exposure duration suffered more surface damaged. The crystallinity percentage
was found to increase with increasing exposure duration.
The electrochemical oxidation of caffeine, a widely over-the-counter stimulant drug, has been investigated in effluent wastewater and deionized water (DIW) using graphite-poly vinyl chloride (PVC) composite electrode as anode. Effects of initial concentration of caffeine, chloride ion (Cl(-)) loading, presence of hydrogen peroxide (H2O2), sample volume, type of sample and applied voltage were determined to test and to validate a kinetic model for the oxidation of caffeine by the electrochemical oxidation process. The results revealed that the electrochemical oxidation rates of caffeine followed pseudo first-order kinetics, with rate constant values ranged from 0.006 to 0.23 min(-1) depending on the operating parameters. The removal efficiency of caffeine increases with applied voltage very significantly, suggesting a very important role of mediated oxidation process. However, the consumption energy was considered during electrochemical oxidation process. In chloride media, removal of caffeine is faster and more efficiently, although occurrence of more intermediates takes place. The study found that the adding H2O2 to the NaCl solution will inhibit slightly the electrochemical oxidation rate in comparison with only NaCl in solution. Liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS) technique was applied to the identification of the by-products generated during electrochemical oxidation, which allowed to construct the proposed structure of by-products.
Introduction: Malaysian traffic police are always working on the public roads to alleviate traffic congestion and therefore exposed them to the polluted air every day. In particular, polluted air containing PM2.5 is dangerous to their respiratory health as they can penetrate deep into the lungs, leading to bronchitis, lung cancer and many more. Hence, this research examined the relationship of personal exposure level to PM2.5 with respiratory symptoms among traffic policemen in Kuala Lumpur and Johor Bahru. Methods: 134 participants among traffic policemen were agreed to participate in this study. They were requested to complete a questionnaire regarding the sociodemographic back- ground and respiratory health information. The questionnaire was adopted from International Union Against Tuber- culosis Lung Diseases (1986). Personal exposure level of PM2.5 was measured using an air pump with 5.0µm pore size PVC filter. Results: The mean exposure level of PM2.5 among traffic policemen was 28.69 µg/m3. It was found that some of them possess respiratory symptoms (Coughing 33.6%, Phlegm 25.4%, Wheezing 14.9% and Shortness of breath 32.1%). There was significant association detected at p-value < 0.05 in coughing. Despite, there was no significant association in other symptoms such as phlegm, wheezing and shortness of breath. Conclusions: Traffic police were exposed to a relatively high level of PM2.5 (12.4 µg/m3 to 55.3 µg/m3) and showed symptoms of respi- ratory effects. Therefore, recognition of the risks connected with occupational lung disease and exposure monitoring must be a high priority. This baseline data can serve as a reference to the top management of traffic police officers in order to develop an occupational safety and health guideline for police officers as required by Occupational Safety and Health Act (OSHA, Act 514 1994).
Elbow length PVC gloves are often recommended for protection against organophosphorus pesticide (OP) exposure in agriculture. However, performance may be reduced due to high temperature, UV exposure and abrasion. We sought to assess these impacts for two OPs under normal use and reasonable worst-case scenarios. Glove permeation tests were conducted using ASTM cells with two PVC glove brands at 23°C and 45°C for up to 8 h. Technical grade dichlorvos and formulated diazinon were used undiluted and at application strength. Breakthough of undiluted dichlorvos occurred at both 23°C and 45°C, but only at 45°C for application strength. Breakthrough of diazinon was not achieved, except when undiluted at 45°C. UV-exposed and abraded gloves showed reduced performance, with the effect being approximately two-fold for dichlorvos. Only small differences were noted between glove brands. Extra precautions should be taken when handling concentrated OPs at high temperature, or when using abraded or sunlight-exposed gloves.
So far, several classes of digesting solutions have been employed to extract microplastics (MPs) from biological matrices. However, the performance of digesting solutions across different temperatures has never been systematically investigated. In the first phase of the present study, we measured the efficiency of different oxidative agents (NaClO or H2O2), bases (NaOH or KOH), and acids [HCl or HNO3; concentrated and diluted (5%)] in digesting fish tissues at room temperature (RT, 25°C), 40, 50, or 60°C. In the second phase, the treatments that were efficient in digesting the biological materials (>95%) were evaluated for their compatibility with eight major plastic polymers (assessed through recovery rate, Raman spectroscopy analysis, and morphological changes). Among the tested solutions, NaClO, NaOH, and diluted acids did not result in a satisfactory digestion efficiency at any of the temperatures. The H2O2 treatment at 50°C efficiently digested the biological materials, although it decreased the recovery rate of nylon-6 (NY6) and nylon-66 (NY66) and altered the colour of polyethylene terephthalate (PET) fragments. Similarly, concentrated HCl and HNO3 treatments at RT fully digested the fish tissues, but also fully dissolved NY6 and NY66, and reduced the recovery rate of most or all of the polymers, respectively. Potassium hydroxide solution fully eliminated the biological matrices at all temperatures. However, at 50 and 60°C, it degraded PET, reduced the recovery rate of PET and polyvinyl chloride (PVC), and changed the colour of NY66. According to our results, treating biological materials with a 10% KOH solution and incubating at 40°C was both time and cost-effective, efficient in digesting biological materials, and had no impact on the integrity of the plastic polymers. Furthermore, coupling this treatment with NaI extraction created a promising protocol to isolate MPs from whole fish samples.
This study was conducted as part of the Human Exposure Assessment Location (HEAL) Project which comes under the United Nations Environment Programme/World Health Organisation (UNEP/WHO) Global environmental Monitoring System (GEMS). The objective of the study was to evaluate workers' exposure to lead in industries with the highest exposure. All subjects were interviewed about their occupational and smoking histories, the use of personal protective equipment and personal hygiene. The contribution of a dietary source of lead intake from specified foods known to contain lead locally and personal air sampling for lead were assessed. A total of 61 workers from two PVC compounding and 50 workers from two lead acid battery manufacturing plants were studied together with 111 matched controls. In the PVC compounding plants the mean lead-in-air level was 0.0357 mg/m3, with the highest levels occurring during the pouring and mixing operations. This was lower than the mean lead-in-air level of 0.0886 mg/m3 in the lead battery manufacturing plants where the highest exposure was in the loading of lead ingots into milling machines. Workers in lead battery manufacturing had significantly higher mean blood lead than the PVC workers (means, 32.51 and 23.91 mcg/100 ml respectively), but there was poor correlation with lead-in-air levels. Among the lead workers, the Malays had significantly higher blood lead levels than the Chinese (mean blood levels were 33.03 and 25.35 mcg/100 ml respectively) although there was no significant difference between the two ethnic groups in the control group. There were no significant differences between the exposed and control group in terms of dietary intake of specified local foods known to contain lead. However, Malays consumed significantly more fish than the Chinese did. There were no ethnic differences in the hours of overtime work, number of years of exposure, usage of gloves and respirators and smoking habits. Among the Malays, 94.3% eat with their hands compared with 9.2% of the Chinese. Workers who ate with bare hands at least once a week had higher blood lead levels after adjusting for lead-in-air levels (mean blood lead was 30.2 and 26.4 mcg/100 ml respectively). The study indicated that the higher blood lead levels observed in the Malay workers might have been due to their higher exposure and eating with bare hands.