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All issues / Volume 15 (2021) / Issue 4 (April)

Automotive plastics: What future is there for polymers in tomorrow's electric and autonomous vehicles?
P. Krawczak
Vol. 15., No.4., Pages 288-288, 2021
DOI: 10.3144/expresspolymlett.2021.25
This is an editorial article. It has no abstract.
Mixed matrix membranes embedded with Janus mesoporous silica nanoparticles for highly efficient water treatment
Z. M. Mi, D. W. Zhang, D. M. Wang, Z. X. Liu
Vol. 15., No.4., Pages 289-307, 2021
DOI: 10.3144/expresspolymlett.2021.26
A periodic mesoporous organosilica (PMO) Janus nanoparticle (PMO-SO3H&SiO2-NR) was gently synthesized and mixed with polyethersulfone (PES) to fabricate a series of mixed matrix membranes via the phase inversion method. The Janus structure of PMO-SO3H&SiO2-NR nanoparticle enabled the hydrophilic –SO3H and hydrophobic hexadecyl (-NR) to be separately distributed on the PMO cores and SiO2 branches, and hence Janus PMO-SO3H&SiO2-NR nanoparticle was endowed with good hydrophilicity and excellent compatibility with PES membrane matrix. As a result, the mixed matrix membranes presented improved bulk porosity, surface mean pore size, hydrophilicity and permeability. Particularly, the pure water flux of the mixed matrix membrane with 5 wt% porous Janus PMO-SO3H&SiO2-NR nanoparticles (M5) was as high as 330 l・m–2・h–1 that was 2.2 times that of the pristine PES ultrafiltration (UF) membrane (M0) while its rejection for bovine serum albumin (BSA) remained above 98.0%. Besides, after multi-cycles UF experiment with BSA as model contaminant, M5 retained a high flux recovery rate, permeation flux and rejection, suggesting its outstanding overall performance. Porous Janus PMO-SO3H&SiO2-NR nanoparticle is the first time to be used as an effective additive to prepare mixed matrix membrane, providing a new approach to achieve highly efficient water treatment of UF membranes.
Effects of protein contents in different natural rubber latex forms on the properties of natural rubber vulcanized with glutaraldehyde
R. Promsung, Y. Nakaramontri, N. Uthaipan, C. Kummerloewe, J. Johns, N. Vennemann, E. Kalkornsurapranee
Vol. 15., No.4., Pages 308-318, 2021
DOI: 10.3144/expresspolymlett.2021.27
This work presents a simple processing way to vulcanize natural rubber (NR) using glutaraldehyde (GA) as a curing agent at low temperature. The effect of different protein contents of NR latex on the resulting properties of the NR vulcanizates is examined in this paper. The protein contents in different NR latex, including creamed-NR (CreNR), centrifuged-NR (CenNR), and synthetic-NR (SynNR) latexes, were successfully analyzed. It was found that CreNR has the highest protein content, followed by CenNR and SynNR, respectively. The influence of protein contents in NR latex on crosslink density, mechanical properties, and thermal stability of the cured NR were investigated and compared. Temperature scanning stress relaxation (TSSR) technique was used to examine the crosslinking among GA and protein molecules, which has inter-particle interactions with NR molecular chain. This was compared with the conventional swelling experiments used in determining the swelling ratio. It is found that the mechanical properties, thermal stability, and the crosslinking density data are strongly related to the protein content in the NR latex, i.e., CreNR > CenNR >Syn NR. This is attributed to the protein strong contacts of the protein content to the NR chain and its ability to propagate chemical crosslinking with GA molecules. Therefore, the protein causes new linkages between rubber molecules through GA.
Thermal conductivity of porous polymer materials considering pore special-shape and anisotropy
X. J. Wang, X. H. Niu, X. X. Wang, X. W. Qiu, N. Istikomah, L. B. Wang
Vol. 15., No.4., Pages 319-328, 2021
DOI: 10.3144/expresspolymlett.2021.28
The thermal insulation performance of porous polymer material is greatly affected by the pore structure. However, the effect of pore special-shape on the thermophysical properties of porous polymer material has not been considered. In this study, the effects of pore shape, overlap, and anisotropy are evaluated at the same time. The results show that the special-shaped pore had a better effect on the thermal insulation performance than common pores. The difference in thermal insulation performance caused by pore shape is increased with the gas content. The thermal insulation performance increases with the pore overlap only when the pores are overlapped in the direction vertical to heat flux. The common and specialshaped pores have different overlap probabilities in the same direction. The special-shaped pore is more sensitive to the directional angle than common pore and has significant anisotropy. Meanwhile, the pore anisotropy is affected by the pore overlap. The manufacture of porous polymer material must pay attention to the directional angle of the special-shaped pore and heat flux direction.
Preparation, characterization, and continuous manufacturing of nonflammable colorless and transparent semi-alicyclic polyimide film modified with phenoxy- phosphazene oligomer flame retardant
X. Wu, L. Wu, L. Qi, L. M. Yin, Y. Yang, G. L. Jiang, X. X. Zhi, Y. Zhang, J. G. Liu, J. T. Wu
Vol. 15., No.4., Pages 329-342, 2021
DOI: 10.3144/expresspolymlett.2021.29
Phenoxy-phosphazene (PPZ) oligomer (Rabitle® FP100) flame retardant (FR) was successfully incorporated into the colorless and transparent semi-alicyclic polyimide (CPI) film matrix derived from 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA) and 4,4′-oxydianiline (ODA) (PI-a, CHDA-ODA). The PPZ FR showed good miscibility with the PI-a matrix with a loading amount of up to 10 wt% in the composite films. PI-b (CHDA-ODA-FP100-5) film maintained good optical properties with the transmittance of 83.9% at the wavelength of 400 nm, the yellow index (b*) of 3.28, and the haze of 2.14%. PI-b film also showed good flame retardancy with the limiting oxygen indices (LOI) of 41.2% and the flammability rating of UL94 VTM-0. In addition, PI-b film exhibited the obviously reduced heat release rate (HRR) and total smoke production (THR) during the cone calorimeter measurement. At last, PI-b showed the glass transition temperature (Tg) and 5% weight loss temperature (T5%) of 325.0 and 404.3 °C, respectively, which was slightly lower than those of the pristine PI-a film (Tg = 346.8 °C; T5% = 431.6 °C). Continuous PI-b films with a length of 1000 m and a width of 1000 mm were successfully obtained on the demonstration production line by optimizing the processing parameters via the modified solvent cast technology. Similar thermal, optical, and flame retardancy properties and obviously improved tensile properties were observed for the mass production of PI-b film.
Poly(lactic acid) bio-composites containing biochar particles: Effects of fillers and plasticizer on crystallization and thermal properties
T. Haeldermans, P. Samyn, R. Cardinaels, D. Vandamme, K. Vanreppelen, A. Cuypers, S. Schreurs
Vol. 15., No.4., Pages 343-360, 2021
DOI: 10.3144/expresspolymlett.2021.30
Biochar has emerged as a filler material for bio-degradable composites with favorable thermal and mechanical properties. Therefore, biochar is used in poly (lactic acid) (PLA) and PLA/thermoplastic starch (TPS) based composites. The crystallization and thermo-analytical properties of these blends with increasing amounts (20 to 50 wt%) of biochar are investigated. In the thermogravimetric analysis, the PLA/char composites’ onset degradation temperature and temperature of maximum weight loss decrease with increasing biochar concentrations (320 to 275 °C and 380 to 350 °C, respectively). Contrastingly, in the PLA/TPS/char composites, the impact of the biochar is shielded by the TPS. The unaltered glass transition demonstrates that biochar does not act as a plasticizer in any of the composites, while TPS does. Biochar acts as a nucleation agent, but hinders further crystal growth at high concentrations, as confirmed by isothermal crystallization and infrared spectroscopy. The TPS smoothens the PLA/biochar interface, leading to an obstructed nucleation effect of biochar, proven by differential scanning calorimetry, infrared spectroscopy, and scanning electron microscopy. This work demonstrates the shielding effect TPS has on biochar and can help to understand further and optimize the production and biodegradability of these composites.
Novel carbon fibres synthesis, plasma functionalization, and application to polymer composites
A. Khan, D. Dragatogiannis, P. Jagdale, M. Rovere, C. Rosso, A. Tagliaferro, C. Charitidis
Vol. 15., No.4., Pages 361-374, 2021
DOI: 10.3144/expresspolymlett.2021.31
PAN copolymers were synthesized via a novel technique, atom transfer radical polymerization (ATRP), with the activator generated by electron transfer method (AGET). Carbon fibers (CF) were synthesized at low carbonization temperatures from the novel PAN precursor. Plasma treatment in an oxygen environment at a low pressure of 40 Pa was carried out for 5 minutes on the CF at 100 and 200 W plasma power. The morphology and structure of the CF changed after plasma functionalization, as evident from SEM analysis and Raman spectroscopy. The formation of functional groups like alcohols, carbonyl, and carboxylic on the surface of CF was confirmed with the aid of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The wetting test confirmed the higher adhesion of the plasma functionalized CF with the epoxy matrix. Single fiber strength test revealed that plasma functionalized CF retained around 98% of their original tensile strength. Composites were fabricated from the pristine, and the plasma functionalized CF in 1 and 3% by weight with epoxy matrix. The surface-modified CF composites depicted improved tensile (23.4%), tribology (33.62%), and surface hardness (11.4%) properties compared to the composites fabricated from pristine CF.
Scale-up and optimization of fenofibrate-loaded fibers electrospun by corona-electrospinning
E. Bitay, Z.-I. Szabo, J. Kantor, K. Molnar, A. L. Gergely
Vol. 15., No.4., Pages 375-387, 2021
DOI: 10.3144/expresspolymlett.2021.32
Scaled-up production of fenofibrate-loaded, polyvinylpyrrolidone-based microfibrous mats was achieved by using corona-electrospinning. An experimental design-based approach was used to study the influence of production parameters on fiber diameter and morphology. Microstructural characterization of the obtained products was performed by scanning electron microscopy imaging and differential scanning calorimetry. Drug content and in vitro dissolution studies were performed in order to monitor the effect of electrospinning on the drug release characteristics from the obtained product. The optimized parameters provided electrospun mats with smooth, homogenous fibers, without beading, which conferred rapid drug release and increased solubility of the lipid-lowering drug. The in vitro dissolution results show 40 times higher fenofibrate release from the fiber mats compared to the micronized active pharmaceutical ingredient. The presented results show that corona-electrospinning is a promising method for scale-up applications, and it could be used in the pharmaceutical industry. The fenofibrate loaded microfibrous mats could treat dyslipidemia, thus prevent heart attack or stroke, by using lower drug content. Lower drug content could also reduce the associated side effects and lowers the cost of treatment.
Published by:

Budapest University of Technology and Economics,
Faculty of Mechanical Engineering, Department of Polymer Engineering