A review of natural fiber reinforced poly(Vinyl alcohol) based composites: application and opportunity

Natural fibers are fine examples of renewable resources that play an important role in the composites industry, which produces superior strength comparable to synthetic fibers. Poly(vinyl alcohol) (PVA) composites in particular have attracted enormous interest in view of their satisfactory performance, properties and biodegradability. Their performance in many applications such as consumer, biomedical, and agriculture is well defined and promising. This paper reviews the utilization of natural fibers from macro to nanoscale as reinforcement in PVA composites. An overview on the properties, processing methods, biodegradability, and applications of these composites is presented. The advantages arising from chemical and physical modifications of fibers or composites are discussed in terms of improved properties and performance. In addition, proper arrangement of nanocellulose in composites helps to prevent agglomeration and results in a better dispersion. The limitations and challenges of the composites and future works of these bio-composites are also discussed. This review concludes that PVA composites have potential for use in numerous applications. However, issues on technological feasibility, environmental effectiveness, and economic affordability should be considered

Burnout, anxiety and depression in healthcare workers during the early COVID-19 period in Singapore

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Environmental friendly poly (vinyl) alcohol/kenaf fiber composites for agricultural applications / Tan Boon Khoon

In this study, poly(vinyl alcohol)/kenaf fibre (PVA/KF) based composites were prepared by casting from a mixture of kenaf fibre and aqueous solution of PVA. Certain amounts of urea could be loaded into the composite. The water solubility, release behaviour of urea and thermal stability of PVA/kenaf fibre/urea composites were evaluated. In a wet environment, urea was released from the composites through its dissolution in water. Around 57% of the urea was released from the PVA/KF composites in 24 hours. The composites also lost 25% of their weight after 7 days in water. Controlled amounts of methylene diphenyl diisocyanate (MDI) were added to introduce some crosslinking reactions between the diisocynante and the –OH groups of the PVA and the fibre to improve the water barrier property of the composites for prolonged water submersion. Laboratory tests were performed on cross-linked and uncross-linked PVA/KF composites to examine the effect of MDI on the properties of the composites. Water-absorption test, morphological analysis, thermal-stability evaluation, and FTIR study were performed. This cross-linked structure was able to slow down the penetration of water and enhance water resistance, as confirmed by the water-absorption test and micrographs. Thermogravimetry analysis data revealed that cross-linking improved the thermal stability of the composites. The degradation of cross-linked and uncross-linked PVA/KF composites in soil was also investigated, where sample pieces of dimension of 20 x 20 x 1 mm were buried 5 cm deep under soil in flower pots. The evidence of degradation could be seen from FTIR spectroscopy. In addition, cracks and fungal growth on the surface of the materials could be clearly observed under the microscope. The rate of degradation could be monitored from the weight loss of the sample, which increased significantly when in wet environment. The observed weight loss of PVA/KF composite was 18% in 7 days and 50% after 28 days, while MDI cross-linked PVA/KF composite exhibited a slower weight loss of 7% in 7 days to 14% after 28 days. The composites were tested in real life conditions by using them as biodegradable mulches for long bean plants in a small garden plot. The degradation of mulches and the plant growth were carefully observed. Their performance was also compared with the plastic mulch using black polyethylene films available in the market. It was found that the biodegradable mulches were able to protect the seedlings of long beans from moisture loss. As the plants have grown stronger within 30 days, the mulches have biodegraded completely, releasing the fibres as fertilizer to the soil without leaving any undegradable waste for disposal. Hence, they would not pose any risks to the land or biological systems. The composites could have great potential agricultural applications

Effect of Oil Palm Ash on the Properties of Polypropylene/Recycled Natural Rubber Gloves/Oil Palm Ash Composites

In the present study, polypropylene, recycled natural rubber gloves, and oil palm ash composites (PP/rNRg/OPA) were prepared using an internal mixer. The effects that OPA loading had on the processability, tensile properties, morphology, and thermal stability of the PP/rNRg/OPA composites were investigated. The stabilization torque, tensile modulus, and thermal stability all increased; however, the elongation at break decreased as the OPA loading increased. The tensile strength increased to a maximum of 4 parts per hundred rubber (phr) OPA loading, and subsequently decreased. At 4 phr OPA, the filler was well-dispersed and had a good interaction with the matrix, whereas the agglomeration and detachment of OPA was observed at high loading rates of OPA in the PP/rNRg/OPA composite. Thermogravimetric analysis (TGA) indicated that the thermal stability of the composite increased as the OPA loading increased. Further evidence for the increased thermal stability can be found when analyzing the decomposition temperatures at different stages and maximum weight loss, where higher decomposition temperatures corresponded to composites with higher OPA loadings

Quality management : does it really pay?

This is an empirical study on publicly available data that sought to investigate the possible existence of relationship between Quality Management (TQM) and common stock performance. The earlier part of the text describes how and why much emphasis has been placed on the Quality Management, as well as providing a probable explanation for such a phenomenon. The latter half of the report records the detailed statistical test methods, where the realised residuals of the sample stock returns are regressed against the SESALL share index over a period of 24 months. The final portion of the text summarizes the findings of the Chi-Square as well as the Student T tests conducted, before concluding that there exists a positive relationship between TQM and common stock performance.BUSINES

The 2000 dotcom crash and the lessons for Singapore dotcoms.

This paper attempts to find out the issues and challenges facing local dotcom companies after the burst of the dotcom bubble that led to the downfall of many dotcom companies. This paper finds out the reasons why dotcoms failed and specifically, how many dotcom companies had failed in Singapore, which was determined by reviewing local dotcom websites obtained from the Department of Statistics

Investment opportunities in Singapore stock market

This report attempts to examine investment opportunities in local stock market and related issues in Singapore. It begins with a brief introduction of the trends in share investments in Singapore. Previous studies on local stock market efficiency are also reviewed in order to assess the return profile of share investments. The history, trading procedure and analysis of past performance of local stock market are also discussed to provide a better understanding on share investment. In addition, the report includes comparisons of share investments with other investment avenues and before a final conclusion of the report.BUSINES

Biodegradable Mulches Based on Poly(vinyl Alcohol), Kenaf Fiber, and Urea

This paper describes the preparation of poly(vinyl alcohol)/kenaf fiber (PVOH/KF) composites with entrapped urea. The major FTIR peaks of these composites could be identified. These composites are intended for agricultural applications as biodegradable mulches and could be potential carrier materials for fertilizer. The water solubility, release behavior, chemical properties, and thermal stability of the composites were evaluated. The composites lost 25% of their weight after 7 days in water. In a wet environment, urea was released from the composites through its dissolution in water, and around 57% of the urea was released from the composites in 24 h; Thermagravimetric analysis showed that these composites were stable up 150 C. These composites would be able to withstand rain and protect seedlings from the sun when applied in the field as mulches. For around three to four weeks, these biobased mulches could slowly disintegrate as the PVOH binder was gradually dissolved by moisture, releasing the kenaf fibers to serve as soil fertilizer without leaving any undegradable waste for disposal. Hence, they would not pose any risks to the land or biological systems