Shen, Lihua;Severn, John;Bastiaansen, Cees W. M.
来源期刊：Polymer: The International Journal for the Science and Technology of Polymers
Ultra-high molecular weight polyethylene (UHMWPE; M-w = 103 kg/mol) is blended with a low molecular weight, linear polyethylene (PEwax; M-w = 1 kg/mol) and the solid state drawing behavior and mechanical properties are explored. The results indicate that the low molecular weight polyethylene wax acts as a solvent for the UHMWPE which leads to an improvement in rheological properties and the maximum attainable draw ratio of the blends. The maximum attainable Young's modulus of the drawn films increases with more than a factor 2 without removal of the solvent. Moreover, it is found that the maximum attainable tensile strength of the drawn blends also increases significantly from similar to 1 GPa to similar to 1.5 GPa upon addition of 60 wt% of the PEwax. Based on these results, a new route is proposed for the processing of highly oriented polyethylene, which has certain characteristics in common with both melt spinning and solution spinning but, in fact, is neither of the two. (C) 2018 Elsevier Ltd. All rights reserved.
Yingsanga, P.;Srilaong, V.;Kanlayanarat, S.;McGlasson, B.;Noichinda, S.
年/卷/期：2012 / / 943
The efficacy of several surface coatings and lime dip in reducing water loss and browning of rambutan (Nephelium lappaceum L.) fruit was examined. Dipping fruit for 5 min in polyethylene wax (Super size Z) at 2:1, 1:1 and 1:2 dilution with water comparably reduced weight loss and delayed browning of the fruit. However, fruit developed off-flavors. On the other hand, sucrose fatty acid esters at 0.1-0.5% did not reduce weight loss but decreased fruit browning. L* and a* values did not correlate with browning scores. Lime as 2% solution was not effective in reducing weight loss and browning. It was concluded that storage at a low but non-chilling temperatures (approximately 13 degrees C) and high RH is required to reduce fungal spoilage, retard water loss and to slow browning.
High density polyethylene oligomers and docosane (C_(22)H_(46)) were subjected to a photochlorination reaction to a chlorine content above 70% as checked by thermogravimetry. The resulting chlorinated materials were dehydrohalogenated by potassium hydroxide in different conditions with simple reaction routes. It is shown by FT-IR, C~(13)-NMR and electronic spectroscopy that soluble low molecular weight polymers were formed having polyyne-ene and polyene-yne segments. These new soluble polymeric materials are of potential interest both in the field of optics and electronics as well as in the understanding the cosmochemical problem of the molecules in interstellar space.
来源期刊：Wear: an International Journal on the Science and Technology of Friction, Lubrication and Wear
The water lubricated bearing is one of the most important components in machine systems, and significantly affects safe operation. Poor lubrication makes it very difficult to ensure good wear resistance in water lubricated bearings, especially at low speed or in complex load conditions. However, polyethylene wax (PEW) offers good self lubricating performance, which may provide lubrication and the required wear resistance in water lubricated bearing materials. In this reported study, a new water lubricated bearing composite material comprised of polyurethane (PU) and a small amount of PEW were fabricated to improve the wear resistance of the PU based water lubricated bearings. The wear behavior of the PU PEW composite material and the PU material was investigated at low speed and at different load conditions at room temperature using the CBZ 1 friction and wear tester. The wear resistance of these materials was evaluated based on the experimental results of the friction coefficient and wear morphologies. The experimental results indicated that the PEW additive was heated by the developed friction and was deposited on the surface of the composite material to form a lubricant film with good lubricity. As a result, the load bearing capacity of the lubricant film was improved, which effectively improved the lubrication conditions of the composite material, thereby improving the wear resistance and decreasing the effect of the load. These results suggest that this study may provide a novel approach for improving the wear resistance and lubrication condition of PU based water lubricated bearings.
来源期刊：Journal of Reinforced Plastics and Composites
年/卷/期：2018 / 37 / 3
This work shows that mechanical properties, thermal conductivity, and secondary gamma-ray shielding ability can be significantly improved when open-cell nickel foams are embedded into the shielding composites. The boracic polyethylene/polyethylene wax blends and open-cell nickel foam composites (PPNM) are designed and prepared by permeating homogeneous mixed melt fillers into open-cell nickel foams. The ratio of polyethylene and polyethylene wax is investigated to achieve higher filling rate. The quasi-static compressive response of PPNMs and polyethylene/polyethylene wax blends is measured, and the crystallization properties are studied by differential scanning calorimetry. The neutron and secondary gamma-ray shielding abilities of PPNMs are also simulated based on Monte Carlo particle transport method. Results show that the compression strength of PPNMs with boron carbide is slightly improved when compared with polyethylene/polyethylene wax blends. The nickel foams in PPNM composites improve the energy-absorbing efficiency by 30%. The thermal conductivity of PPNMs is 300% higher than polyethylene/polyethylene wax. The calculated results show that neutron-shielding abilities of PPNMs increase as content of boron carbide increases. Moreover, secondary gamma-ray shielding ability of PPNMs containing boron carbide is obviously higher than polyethylene/polyethylene wax. The PPNMs containing boron carbide neutron-shielding materials are proved to have good thermal conductivity, mechanical properties, and radiation-shielding ability.
A new multi-functional binder with adhesive and lubricant effect was designed, and the thixotropic properties of the binder components and the resulting binder, the adhesive effect and compaction behaviour of the binder-treated powder were investigated. The results demonstrate that the thixotropic components in the binder are polyethylene wax and microcrystalline wax. With the increase of polyethylene wax content, the critical solid-liquid shear stress of binders decreases gradually. The main lubrication components in the low-pressure and high-pressure stages during the compaction process are found to be polyethylene wax and microcrystalline wax, respectively. The fine metal or graphite additives are effectively bonded on the surface of iron particles and filled in the pits. The green density reaches 7.25 g cm(-3) at 600 MPa when the content of polyethylene wax is 30%. From 400 to 750 MPa, the content of polyethylene wax corresponding to the minimum ejection pressure decreases from 20 to 0%.
Brzezinska, Maria Swiontek;Walczak, Maciej;Burkowska-But, Aleksandra;Chylinska, Marta;Kalwasinska, Agnieszka;Swiatczak, Joanna
来源期刊：Journal of polymers and the environment
年/卷/期：2019 / 27 / 8
Experiments were conducted to investigate the antifungal activities of polyhexamethyleneguanidine (PHMG) derivatives introduced into polylactide (PLA), polyhydroxybutyrate (PHB) and polycaprolactone (PCL) against Aspergillus niger, Penicillium chrysogenum and Candida albicans. All of the PHMG derivatives inhibited the germination of A. niger and P. chrysogenum. All of the derivatives exerted a much stronger inhibitory effect on the cells of C. albicans. PHMG granular polyethylene wax (at the concentration of 1.0%) has a fungicidal effect. The reduction in the number of yeast cells capable of growing on the surface composites PLA, PHB and PCL with PHMG granular polyethylene wax for 24h was R>2. PHMG derivatives introduced into PLA decreased hydrolases activity in A. niger and P. chrysogenum. All of the PHMG derivatives introduced into all investigated polymers inhibited the hydrolases activity in C. albicans proportionately to concentration. PHMG granular polyethylene wax at a concentration of 1.0% most strongly inhibited hydrolases activity in yeast. The composites produced from PLA, PHB, PCL and this PHMG derivatives can be used in many areas to reduce the growth of yeast. The studied composites can potentially be used for the production of biomedical or packaging materials.Graphical AbstractPHMG derivates introduced into polymer have slightly biocidal properties against molds and strong against yeast. The composites produced from PLA, PHB, PCL and this PHMG derivatives can be used in the many areas to reduce the growth of yeast. The studied composites can potentially be used for the production of biomedical or packing materials.[GRAPHICS].
Kleinsasser, Jack F.;Reinhart, Erik D.;Estrada, Jess;Jordan, Richard F.;Lavallo, Vincent
年/卷/期：2018 / 37 / 24
The synthesis and ethylene reactivity of the zwitterionic Pd methyl complexes (kappa(2)-P,Cl-PR2CB9Cl9)PdMe-(THF) (7, R = Pr-i; 8, R = Ph) and (kappa(2)-P,O-P(o-OMe-Ph)(2)CB9Cl9)PdMe(THF) (9), which contain the first phosphines appended with anionic 10-vertex perchlorinated closo-carboranes, are described. Complexes 7 and 8 oligomerize ethylene (23 degrees C, 2 atm) to a Schulz-Flory distribution of C-4-C-10 olefins with TOFs of ca. 8000 and 1800 t.o./h, respectively. 8 is ca. 4 times more active than the analogous (kappa(2)-P,F-ortho-PPh2C6H4BF3)PdMe(L) (L = pyridine or collidine) system reported by Jordan and Piers, which produces butenes. Complex 9 reacts with ethylene to yield polyethylene wax (M-n ca. 1000, D ca. 1.5) that is similar to commercial Fischer-Tropsch waxes. The activities of 7-9 are independent of ethylene pressure and the presence of B(C6F5)(3), suggesting that the catalyst resting state is the corresponding (PR2CB9Cl9)PdR(H2C=CH2) adduct. The molecular weights of the oligomer/polymer products are independent of ethylene pressure, which is consistent with an associative chain transfer mechanism. Reaction of 9 with ethylene generates the corresponding ethylene complex (kappa(2)-P,O-P(o-OMe-Ph)(2)CB9Cl9)PdMe(H2C=CH2), which inserts ethylene at -20 degrees C with a barrier (Delta G(insertion)(double dagger)) of 18.1 kcal/mol.