Volume 43, Issue 3

Because of its dimensional stability, minimal shrinkage, chemical and fire resistance, good mechanical qualities and high resistance to a variety of solvents, acids and water, bismaleimide (BMI) thermosetting polymers are mostly employed in aerospace applications. Corrosion prevention has also been accomplished using BMI coating. The addition of inorganic materials like metal oxides can influence the properties of BMI as an inorganic–organic composite. Ferric chloride–bismaleimide (FeCl 3 –BMI) and titania–bismaleimide (TiO 2 –BMI) composites were synthesized. Fillers of inorganic compounds like MnO 2 , Ni (NO 3 ) 2 ·6H 2 O and Al 2 (SO 4 ) 3 were synthesized as well. The structural and crystalline configuration as well as physicochemical changes were thoroughly studied by XRD and Fourier transform infrared spectroscopy (FTIR).

The non-isothermal crystallization kinetics of ethylene-tetrafluoroethylene copolymer (ETFE, Fluon ® C-88AXP) was studied by using differential scanning calorimetry (DSC). The Jeziorny, Ozawa, Mo, and Kissinger equations have been used to describe the crystallization data. The Ozawa and Kissinger plots show downward curves instead of the linear relationship as predicted. Good linear relationship was obtained using the Jeziorny and Mo equations but no vital model parameters concerned with the crystallization kinetics could be acquired. The integral Avrami equation combining with Hoffman equation has been used to describe the crystallization data through nonlinear regression method and kinetic parameters have been acquired. The fitting quality improves when the thermal lag effect was taken into consideration. Meanwhile, the linearity of the Ozawa and Kissinger analysis is improved greatly and the Ozawa exponent and crystallization activity energy of the copolymer have been obtained.

Fiber reinforced polymer composites (FRPC) are widely used in current developing world due to their huge advantages of high specific strength, durability, low cost and weight reduction. But, major issue with this composite is their recyclability. To overcome this, researchers are considering polyolefin fiber for reinforcement purpose which can be reused and recycled and can be used as a reinforcement for concrete for industrial pavement to improve their tenacity. Polyolefin fibers also offer exterior impact strength to the composite because of their ductile nature. Due to their excellent impact property, they are used in high ballistic armor. This review paper contains the details about the FRPC, their processing technique, recent advancement in the processing technique VARIM, polyolefin fiber, properties of polyolefin fibers like polyethylene fiber and polypropylene fiber, polyolefin reinforced polymer composite, hybrid composite and their applications.

In this study, polypyrrole was prepared by in situ chemical oxidation polymerization and deposited on the surface of the PTFE membrane. The surface morphology of the membrane shown that the membrane fouling degree of the modified membrane was much lower than that of the original membrane. Besides, the contact angle value decreased from 107.20° to 72.62°, and its hydrophilicity was significantly enhanced. It took humic acid (HA) as a typical representative membrane foulants, and static and dynamic HA adsorption experiments were carried out on the membranes before and after modification. In the static adsorption experiment of HA, the adsorption capacity of an original membrane was 1.28 times that of a modified membrane. In the dynamic antifouling experiment of HA, the rejection of the modified membrane to HA was 62.99%, while that of the original membrane was only 39.82%. In addition, the experimental results showed that the modified membrane had a higher flux recovery rate, which was 1.18 times that of the original membrane. This study proves that the modified membrane has an extraordinary antifouling effect.

The performances of five cellulosic polymers with different functional groups (cellulose, cellulose acetate, cellulose phosphate, chitosan, and chitin) as sorbents of seven frequently used hazardous polar organic liquids (acrolein, butanone peroxide, epichlorohydrin, formaldehyde, furfuryl alcohol, propylene oxide, and vinyl acetate) are investigated in this study. Amongst the cellulosic sorbents, cellulose phosphate exhibited enhanced sorption properties (as high as 3.09–7.03 g/g) against all seven polar organic liquids investigated, and chitosan and chitin also demonstrated comparable sorption efficiencies (2.28–7.72 g/g and 2.55–5.86 g/g, respectively) to those of cellulose phosphate. According to our investigation, the enhanced sorption efficiency could be achieved due to low powder density of cellulose phosphate, which is caused by the weak intramolecular interaction amongst the polymer chains. In addition, cellulose phosphate, chitosan, and chitin also showed enhanced absorbed solvent recovery percents (71.4, 60.6, and 61.1%, respectively, in average) compared with that of pristine cellulose (43.8%). With excellent sorption efficiency, enhanced solvent recovery rate, and reusability after drying, these functionalized cellulosic sorbents can be excellent candidates to replace the conventional carbon and vermiculites-based sorbents, especially for liquid polar organic spill sorption.

Polyvinylidene fluoride (PVDF) membrane was prepared by a two-step method of surface gelation-immersion precipitation. The surface of the scraping solution film was sprayed with polyvinyl alcohol (PVA) aqueous solution to gel the film surface first, and then the liquid film was immersed in a coagulation bath for phase transformation to obtain the surface modified PVDF membrane. The effects of PVA solution with different mass fraction on the structure and properties of PVDF membrane were studied. The results showed that with the increase of spraying PVA mass fraction, the contact angle of the upper surface of PVDF membranes gradually decreased, the porosity and mean pore size of PVDF membranes gradually increased, and the crystallinity of PVDF membranes gradually decreased. The pores on upper surface of the membranes first increased and then decreased, and the finger-like macropore structure appeared inside the membranes, the water flux first increased and then decreased, and the rejection rate increased. Dynamic cycle filtration experiment of bovine serum protein (BSA) solution showed an increase in membrane flux recovery from 68.31 to 95.08% and a decrease in the irreversible fouling rate from 31.69 to 4.92%, indicating an improvement in the hydrophilicity and antifouling properties of the modified PVDF membrane.

The framework of the present study is based on investigation of different types of phosphorus based secondary antioxidants and their role in stabilization of polypropylene. Three different chemical entities i.e., Tris (2,4-di-tert-butylphenyl) phosphite, Tetrakis (2,4-di-tert-butylphenyl)-4,4-biphenyldiphosphonite and Bis (2,6-di-tert-butyl-4-methylphenyl pentaerythritol-diphosphite) have been studied for its efficiency as a secondary antioxidants or processing stabilizer. Thermal stability of polymer is predicted using degradation kinetics study and correlated with it’s optical, thermal and rheological response. To further evaluate performance of secondary antioxidants, thermogravimetry analysis was performed for polypropylene at three different heating rates and processed for iso-conversional analysis to get the kinetic parameters. Oxidation induction data and kinetic parameters have been related with efficiency of the stabilizers. Filtration study was also carried out to understand the efficacy of stabilizers during secondary process. Die pressure build up in filtration study is quantified and related with performance of secondary antioxidants.

This paper investigated anti-icing behavior and wettability of droplets on superhydrophobic polymercoatings between lotus effect and petal effect, which were prepared on surfaces of 2021 aluminum alloy with 1H, 1H, 2H, 2H-heptafluorodecyl (FAS-17). The prepared surfaces displayed excellent hydrophobicity with contact angles of 154.9° ± 1.5°and 139.8° ± 1.3°, while rolling angles are 4° ± 1.0° (lotus effect) and 30° ± 1.5° (petal effect). Thus, the present study focused on the different characterizations and the anti-icing potential of the superhydrophobic polymersurfaces were analyzed based on three parameters including the icing delay time, the crystallization temperature of water droplets, and contact time of impinging droplets on the cold superhydrophobic polymer coatings (−15 °C). Furthermore, the anti-icing of superhydrophobic coatings between lotus effect and petal effect with freezing time and crystallization temperature experimental phenomena were consistent with the thermodynamic analysis. It is also proved that the droplets have different bounce behavior on different polymercoating surfaces by droplet impact experiment. The study offers a comprehensive perspective on polymercoatings of different wetttablility for anti-icing behavior applications.

In this work, a new model is developed by modifying the existing Maxwell–Wagner–Sillars (MWS) model to predict the gas separation properties of mixed matrix membranes (MMMs). The new modified MWS model, for the first time, provides the simultaneous exploration of the role of nanofillers/matrix interface voids and the exact geometrical shape of nanofillers in predicting the gas separation properties of MMMs. To unveil the crucial role of nanofillers/matrix interface voids, a mixed matrix membrane is considered a three-component system composed of the polymer matrix as the continuous component, nanofillers as the dispersed component and the interface voids between the two components. Moreover, the new model elucidates the role of the exact ellipsoidal shape of nanofillers within the membrane on the gas separation of MMMs by considering the shape factor of nanofillers. The newly developed modified MWS model is accurately able to predict the gas permeation of MMMs with a lower average absolute relative error ( %AARE ) of around 8% compared with the around 30% for conventional models such as the Maxwell model, Bruggeman model, Lewis–Nielsen model and Pal model and even compared with the modified Maxwell model (∼24%).