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Chlorinated poly(vinyl chloride) (CPVC)/calcium carbonate nanocomposites were successfully prepared by the incorporation of calcium carbonate (CaCO 3) nanoparticles into the CPVC matrix. The compatibility between the two phases was obtained by surface modification of the CaCO 3 nanoparticles with stearic acid, leading to improved material performance. The effects of the addition of different amounts of CaCO 3 nanoparticles to the CPVC on the thermal, mechanical, and morphological characteristics of the CPVC/CaCO 3 nanocomposites were investigated. The thermal stability of the CPVC/CaCO 3 nanocomposites was evaluated by thermogravimetric analysis and differential scanning calorimetry. In addition, the surface texture of the CPVC and the dispersion of the CaCO 3 were evaluated using scanning electron microscopy. Important enhancements in the thermal and mechanical properties of the modified CPVC/CaCO 3 nanocomposites were obtained by incorporating different amounts (2.00%, 3.75%, and 5.75%) of surfacemodified CaCO 3 nanoparticles within the CPVC polymer matrix. The results reveal that 3.75% of CaCO 3 was the optimum amount, where the CPVC/CaCO 3 nanocomposite shows the highest impact strength, the highest tensile strength, the highest thermal stability, and the lowest elongation percentage. Replacement of the commercial impact modifier used in industry with the prepared surface-modified CaCO 3 nanoparticles for the development of CPVC was successfully achieved.

Dyed poly(vinyl alcohol) (PVA) films prepared by a simple technique of casting aqueous PVA solution incorporating a mixture of two dyes namely chlorophenol red (CPR) and Quinaldine Red (QR) on a horizontal glass plate are useful as high dose dosimeter in the dose range 2-30 kGy range. The colour of these films change from deep red to yellow when exposed to gamma radiation. Chloral hydrate was added with different concentrations. The response of the prepared films can be modified either by change of chloral hydrate concentration or ratio of the two dyes. As a result, these films can be used as a dosimeter in two dose ranges. The dosimetric parameters, e.g.; dose response, effect of relative humidity on response as well as pre-and post-irradiation stability of these films have been investigated.

Purpose The purpose of this paper is to prepare superabsorbent polymers (SAPs) based on acrylic acid, which is considered hygroscopic material to incorporate in rubber formulation, which results in producing moisten rubber that is used as roofing sheets. Design/methodology/approach SAPs were synthesized via free radical bulk polymerization technique using different content of cross-linker N, N'-methylenebisacrylamide and potassium persulfate. Differential scanning calorimeter, thermal gravimetric analysis, Fourier transform infrared spectroscopy and transmission electron microscopy were used to characterize SAPs and confirmed the formation of cross-linked hydrogel structure. The water absorbency and the gel fraction for sodium polyacrylate (NaPA) were investigated. Then, the influence of obtained NaPA on the swelling behavior of the prepared natural rubber (NR) compound has been discussed. Findings Absorption characteristics and gel fraction of NaPA were found to depend on the content of the cross-linker in the system. SAPs are used to improve the absorbance behavior and performance of the NR to produce, roofing sheets using in hot weather. The morphology of the obtained rubber compound was well-explained by using a scanning electron microscope. Research limitations/implications The research provides a simple way to produce moisten rubber that can be used as a roofing sheet to overcome warm weather. Originality/value Moisten rubber roofing sheets provide a low-cost option in many developing countries with hot climates, and thus, help save the environment from global warming.

F IVE analogues of Polymyxin E1 antibiotic were synthesized via Fmoc-solid phase peptide synthesis (SPPS) strategy using Biotage® Initiator+Alstra™ microwave peptide synthesizer. The aim of this work is to study the importance of the cyclization conditions of the lactam ring on the purity and yield of the final compounds. For this purpose, replacing L-Thr10 with L-Asp allowed the application of different cyclization methodologies. In all analogues, the Dab5,8,9 residues were replaced with Arg, while the Dab4 residue involved in lactam cyclization was replaced with Lys. Modification of the linear tripeptide tail was applied to two of the analogues. The obtained compounds were characterized with different spectroscopic techniques and will be tested for their antimicrobial activity.