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The effect of cleaning process at mild conditions towards PVDF membrane stability is investigated. Two commonly used cleaning agents (NaOH and NaOCl) were found to reduce PVDF membrane stability. The protein retention performance of membrane is reduced subsequent to membrane cleaning process. The stability of PVDF membrane was affected even at a chemical concentration of 0.01 M. a b s t r a c tAppropriate selection of cleaning agent is an important factor to achieve a better cleaning efficiency and this topic has become an ongoing discussion. This work assesses the impacts of sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl) aqueous solution towards polyvinylidene fluoride (PVDF) stability at the typical concentrations used in membrane cleaning. The cleaned membranes were characterised using field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), pure water flux measurement, contact angle, protein retention and tensile testing. Membrane cleaned at elevated temperature and higher concentration presented a higher water flux than the virgin membrane which can be a worrying sign of alteration in membrane properties. The FTIR spectra indicated that the alteration in chemical composition of the membrane causes a reduction in the degree of hydrophilicity. The mechanical properties of the membrane were compromised based on the declination of tensile strength. The findings from this work suggest that the usage of NaOCl as compared to NaOH causes a more detrimental effect towards the stability of the PVDF membrane.

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Nanocomposites based on low-density polyethylene (LDPE), containing 0.5, 1, 2, 3, and 5 wt% of nanoalumina, were prepared by melt-mixing at 125°C and hot melt-pressing to thin polymer film at 125°C. To enhance the interfacial interaction between alumina and LDPE, alumina surface was treated with silane which acts as coupling agent. The effects of alumina additions to the structure and morphology of LDPE matrix were characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. The mechanical behaviour of nanoalumina-reinforced LDPE composite was studied using tensile tests, flexural tests, and impact tests. The interfacial adhesion between nano alumina particle and LDPE matrix was investigated. The result showed that the reinforcement performance of nano alumina to LDPE matrix was attributed to the interfacial adhesion between nanoparticle and polymer matrix. The addition of 1 wt% nano alumina has successfully enhanced the mechanical properties of LDPE material.