Volume 40, Issue 10

Glycidyl azide polymer (GAP) is well known as an energetic prepolymer, but its application as a binder in propellants is limited due to its relatively high glass transition temperature and relatively poor mechanical properties. Copolymerization of GAP with polypropylene glycol (PPG) has been shown to improve GAPs properties because of the good thermal and mechanical properties of PPG. In this research we synthesized triblock copolymer of PPG-GAP-PPG and the compatibilities of this copolymer were investigated with energetic plasticizers (20% w / w ) n -butyl nitroxyethylnitramine (BuNENA), trimethylolethane trinitrate (TMETN), and butanetriol trinitrate (BTTN) by solubility parameter, differential scanning calorimetry (DSC), rheological analysis, scanning electron microscopy (SEM) and vacuum stability test (VST). The DSC results showed that BuNENA had better compatibility with the triblock copolymer in comparison to TMETN and BTTN. It reduced the T g of PPG-GAP-PPG from −58 to −63 °C. The rheological analysis was in good agreement with the DSC results obtained for the compatibility of the plasticizers. In the case of the addition of 20% w / w BuNENA, the viscosity of copolymer/plasticizer decreased from 550 to 128 mPa s, indicating appropriate compatibility of plasticizer with the copolymer. SEM images showed a better distribution of BuNENA in the copolymer matrix.

Two conductive carbon materials, one with a beaded-like structure (carbon black, ECP) and another with tube-like structure (functionalized multi-walled carbon nanotubes, FMWCNTs), were added into a poly(amide-imide) (PAI) matrix. Combining the advantages of ECP (good compatibility) and FMWCNT (high conductivity), the conductivity was improved from 3.7 S m −1 for PAI/FMWCNT polymer composites to 100 S m −1 for PAI/FMWCNT/ECP ternary conductive polymer composites, much higher than that of the sum of PAI/ECP and PAI/FMWCNT. The tensile strength increased from 40 to 70 MPa. The improved conductive and mechanical properties were mainly due to much more intensive conductive network produced in the PAI/FMWCNT/ECP ternary composites, which is useful for electron flow and stress spread. The number of hydrogen bond was increased by adding ECP into PAI/FMWCNT binary composites, and played an important role in forming the unique morphology as evident by Fourier transform infrared spectrometry (FTIR) and X-ray diffraction (XRD) measurements. These conductive composites have potential for flexible electronic applications.

The engagement of waste tires rubber as source of raw materials for different applications can be a partial solution to the great environmental problems caused by these products. In this study, waste tire rubber was devulcanized using both mechano–chemical and microwave methods. This process was achieved using different concentrations of 2-mercapto benzothiazole disulfide (MBTS) and tetramethylthiuram disulfide (TMTD) as a devulcanizing agent and different microwave devulcanizing times. The optimum content of both MBTS, TMTD and suitable microwave treatment time to make continuous film were noted. The devulcanized waste rubber was then added, at different concentrations, to virgin styrene–butadiene rubber (SBR). The thermal properties and dynamic mechanical behaviors were investigated for all blends. The thermal analysis proved that natural and styrene butadiene rubber are the main two constituents of the waste tire rubber utilized in this study. The mechanical behavior of the SBR blends remarkably improved by using 20 phr waste rubber (WR) devulcanized by 2 phr MBTS and by exposure for 2.2 min to microwaves. Storage modulus, tearing strength and tension set behaviors notably improved for all SBR/WR blends by irradiating with gamma ionizing radiation with a dose of 100 kGy and further improvement could be attained by increasing the dose up to 200 kGy.

Non-small cell lung cancer (NSCLC) contributes to about 85% of lung cancer. By 2040, lung cancer cases estimated to rise to 3.6 million globally. Brigatinib (BG) acts as tyrosine kinase inhibitors that target the epidermal growth factor receptor of the epithelial lung cancer cells. BG loaded nanosponges (NSs) were prepared by the emulsion solvent evaporation technique using ethylcellulose (EC) and polyvinyl alcohol (PVA) as a stabilizer. Eight formulations were developed by varying the concentration of the drug (BG), EC and PVA followed by optimization through particle characterization; size, polydispersity index (PDI), zeta potential (ZP), drug entrapment and loading efficiency. The optimized formulation BGNS5 showed particles size (261.0 ± 3.5 nm), PDI (0.301) and ZP(−19.83 ± 0.06 Mv) together with entrapment efficiency (85.69 ± 0.04%) and drug loading (17.69 ± 0.01%). FTIR, DSC, XRD, and SEM showed drug-polymer compatibility, entrapment of drug in EC core, non-crystallinity of BG in NS and confirm spherical porous nature of the NS. BGNS5 reflects drug release in a sustained manner, 86.91 ± 2.12% for about 12 h. BGNS5 significantly decreased the cell viability of A549 human lung cancer cell lines with less hemolytic ratio compared to pure drug BG and EC. Based on the aforementioned results BGNS5 could be used in the effective treatment of NSCLC.

Composite-nanofiltration membranes based on polysulfone (PSU) and functionalized graphene oxide (f-GO) were prepared for dye removal from aqueous media. Graphene oxide (GO) was introduced to enhance the performance of these membranes. GO was functionalized using an aminated heterocyclic compound, namely 6-amino-4-(4-nitrophenyl)-3-methyl-4-phenyl-4,7-dihydro-1H-pyrazolo-[3,4-b]pyridine-5carbonitrile. The f-GO was incorporated into the PSU membrane matrix in different weight ratios (0.25, 0.5, 1, 2 and 4 wt %). Characterizing the produced membranes with scanning electron microscope, Fourier Transform Infrared - Attenuated Total Reflectance (FTIR-ATR) and X-ray diffraction indicated the well dispersion of f-GO in the membrane matrix. The obtained membranes were applied to remove Congo red and methylene blue, as typical anionic and cationic dyes respectively from water. The modified membranes showed superior efficiency in terms of water flux and dye rejection upon being compared with the control membrane. The composite membranes loaded with f-GO exhibited promising dye removal efficiency for both dyes.

A new poly (vinyl chloride) (PVC) membrane electrode using 2-benzoylpyridine semicarbazone as membrane carrier with dioctylphthalate as plasticizer and sodium tetraphenylborate (NaTBP) as anion excluder has been fabricated and investigated as Zn(II)-selective electrode. Best potential response is observed for the composition PVC 30%, plasticizer 58%, NaTBP 8% and ionophore 4% (w/w). The sensor showed a linear stable response over a concentration range of 1.0 × 10 −2 –4.56 × 10 −6  M with a detection limit of 2.28 × 10 −6  M and a response time <10 s. The electrode can be used for at least six months without any divergence in potential.

The main objective of this study was to assess the effectiveness of TiO 2 -Al 2 O 3 nano-mixture used as filler in improving packaging films performance. Polylactic acid/titanium dioxide (PLA/TiO 2 ), polylactic acid/alumina (PLA/Al 2 O 3 ) and polylactic acid/TiO 2 -Al 2 O 3 (PLA/TiO 2 -Al 2 O 3 ) nanocomposite films were successfully prepared via melt mixing process and thoroughly characterized by FTIR spectroscopy, X-ray diffraction (XRD), UV–vis spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The properties such as heat resistant, barrier, mechanical and antimicrobial properties, required for food packaging have also been investigated. As compared to the neat PLA film, the developed PLA nanocomposites have displayed superior properties particularly the PLA/ TiO 2 -Al 2 O 3 nanocomposite film. This resulted material has showed a 22 °C increase in its thermal stability versus 14 and 2 °C in the cases of PLA/TiO 2 and PLA/Al 2 O 3 respectively, and a 54% reduction of its water vapor permeability in comparison with 47% for PLA/TiO 2 and 39% for PLA/Al 2 O 3 . In addition, the PLA/TiO 2 -Al 2 O 3 had a significant enhancement of its mechanical properties. Its Young modulus increased by 102% unlike 23.60% for the PLA/TiO 2 and 44.66% for the PLA/Al 2 O 3 . It was also noticed that this nanocomposite film demonstrated stronger antibacterial activity than the two others. The bacterial growth inhibition effect of TiO 2 -Al 2 O 3 nano-mixture against Pseudomonas aeruginosa and Escherichia coli bacteria was more effective than that of its two constituents.

Hexagonal boron nitride (h-BN) nanoplatelets (0.6 μm in diameter and 100 nm in thickness) are introduced into epoxy resin to improve the polymer’s thermal conducting ability. As expected, the thermal conductivities (TCs) of the composites, especially the in-plane TCs, are significantly increased. The in-plane TC of the epoxy composites can reach 1.67 W/mK at only 0.53 wt% loading, indicating h-BN nanopletelets are very effective thermal fillers. However, after carefully studied the correlation of the TC improvement and filler content, a sudden drop of the TC around 0.53 wt% filler loading is observed. Such an unexpected decrease in TC has never been reported and is also found to be consistent with the T g changes versus filler content. Similar trend is also observed in other 2-D nanofillers, such as graphene oxide, reduced graphene oxide, which may indicate it is a general phenomenon for 2-D nanofillers. SEM results suggest that such sudden drop in TC might be coming from the enrichment of these 2-D nanofillers in localized areas due to their tendency to form more ordered phase above certain concentrations.

Laser direct joining of carbon fiber reinforced thermoplastic (CFRTP) composite plate and titanium alloy plate with a thickness of 2 mm was performed with swing laser. Numerous air bubble of submillimeter size were observed inside the fusion zone of CFRTP and titanium alloy at the cross section of the joints. The air bubble characteristics were analyzed based on the morphology and size, while the formation mechanism of air bubble was further elucidated according to the nucleation mode, nucleation site and nucleation position. The results demonstrated that the nucleation modes of air bubble are substantially divided into homogeneous nucleation and heterogeneous nucleation, which is related to the nucleation sites. The nucleation mode presents a crucial factor influencing the position and morphology of air bubble. In addition, the air bubble characteristics are also determined by the clamp pressure and resin flow. The final morphology of air bubble is primarily represented by four typical types.

Quality consistency is essential in maximizing the productivity rate of the injection molding process and minimizing the production cost. The quality consistency problem is particularly acute in the case of injection molding processes performed using regrind resin, for which the rheological properties are less uniform and more unpredictable than those of virgin material. Accordingly, the present study proposes a two-stage approach for optimizing the injection molding process parameters in such a way as to achieve a consistent molding quality over repeated injection molding cycles. In the first stage, the values of the injection speed/pressure, velocity-to-pressure (V/P) switchover point, and packing pressure are individually determined based on an inspection of the cavity pressure profile and machine parameters provided by the injection molding machine controller. In the second stage, a robust parametric search method based on a first-order regression model is employed to determine the optimal combination of the process parameter settings. Using an Integrated Circuit (IC) tray fabricated from regrind resin for illustration purposes, the results confirm that the proposed method overcomes the problem of small variations in the melt quality and therefore provides an effective technique for improving the yield rate and quality of the continuous mass production.