Co-reporter:Jihua Zhang, Hui Zhang, Shutao Wang, Mingjie Liu
Polymer Degradation and Stability 2017 Volume 144(Volume 144) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.polymdegradstab.2017.08.006
Aging-resistance is an important property of rubber products for their long-term applications. Antioxidants are widely used in the rubber formula to prevent its oxidative aging. However, the blooming of antioxidants results in loss of aging protection and induces toxicity and pollution, which limit their amounts in the rubber. Herein, a novel strategy to avoid such a blooming and improve the aging-resistance of polar acrylonitrile-butadiene rubber (NBR) composites was proposed by doping sustainable carbon nanotubes (CNTs) with antioxidants. Phenolic antioxidants, 3,9-bis-{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl-)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) were chemically grafted and then physically absorbed to CNTs, therefore CNTs with rich antioxidants (CNT-AO80) were prepared, whose total loading efficiency of AO-80 reached 10.3 wt%. In CNT-AO80, physical loading amounts of antioxidants were 3.7 wt% and strongly suppressed by those parts from chemically grafting (6.6 wt%), developing a distribution of antioxidant around CNTs. When 20 phr CNT-AO80 were added to NBR, they allowed a good dispersity and reinforcement for the composites. After naturally aging for 1 year and a 60-day thermal-oxidative test at 90 °C, the NBR composite with CNT-AO80 gave a low variation of mechanical property without AO-80 blooming, showing a good oxidative aging resistance. We believe that the design of loading antioxidants to CNTs may provide an effective solution to extend the service lifetimes of the rubber products.
Co-reporter:Xianliang Sheng, Hongming Bai and Jihua Zhang
RSC Advances 2015 vol. 5(Issue 38) pp:29931-29938
Publication Date(Web):17 Mar 2015
DOI:10.1039/C4RA15078C
To understand sweat transportation along a single hair fiber, its capillary rise was observed. But the effects of hair cuticular cells on the process were difficult to identify due to their submicron scales. In order to deal with the problem, an analogical model of a conical frustum with ratchet-like sides was developed. Side microstructures of the model block the rise of water; moreover, the contact line and contact angle (θ) are more sensitive to such microstructures than wetting height, and there holds the relation between θ and time (t): θ ∼ t−n (n > 0.5). Similarly, the dynamic θ is verified to fit the wetting of the hair fiber. In contrast with a smooth artificial fiber, the introduction of cuticular cells positively speeds up the transportation of liquid (e.g. sweat) along the hair fiber. In addition, hair cleaning is emphasized because oily liquid easily covers the hairs, preventing the transportation of sweat. We believe that our findings are of important significance for cosmetic applications.
Co-reporter:Jihua Zhang, Huadong Feng, Weitao Zao, Mingbo Ling and Yunfeng Zhao
RSC Advances 2014 vol. 4(Issue 89) pp:48443-48448
Publication Date(Web):09 Sep 2014
DOI:10.1039/C4RA07842J
Recently, one interesting wetting phenomenon was found whereby a live frog can stably stand or easily jump on a floating lotus surface. Inspired by the floating leaf, constructing a lotus-like substrate is important to provide powerful aquatic support. In this article, a flexible and light-weight superhydrophobic paper was successfully fabricated by coating a mixture of polystyrene-poly(methyl methacrylate) copolymer (PS-co-PMMA) and silica nano-particles. The micro/nano structures from the composite coating render common papers to possess superhydrophobic surfaces with low adhesion. The coated paper restricts capillary absorption owing to its high water-repellency; moreover, it has an ultra-low absorption when completely soaked into water. A lotus-like support model with some origami frogs is made to display the floating feasibility of the coated paper. The maximum supporting force of the coated paper with an area of 30 × 30 mm is equivalent to ∼68 times its own weight. The simple force analysis illustrates that the great carrying capacity of the coated paper comes from its superhydrophobicity. Importantly, the flexibility of the coated paper possibly gives rise to its good dynamic floating stability. We believe that flexible superhydrophobic paper can be practically applied to some smart designs like aquatic micro-devices.
Co-reporter:Jihua Zhang;Weitao Zao;Lifeng Wang;Yunfeng Zhao;Hongming Bai
Polymer Composites 2014 Volume 35( Issue 7) pp:1306-1317
Publication Date(Web):
DOI:10.1002/pc.22781
The low-temperature grade hydrogenated nitrile butadiene rubber (LTG-HNBR) composites with organoclays were successfully prepared for the purpose of using the clay-networks to improve bulk properties. In order to construct different clay-networks, three montmorillonite (MMT) modified by surfactants were added and then their dispersions and affinities in the rubber were compared. Transmission electron microscope and small-angle X-ray scattering results showed that 10 phr organoclays form partially exfoliated and intercalated structures in the matrix despite of modifier types. FTIR and particle analysis data display that increasing the number of alkyl tails of modifier molecules decreases the affinities of clays and their extent of intercalation in rubber whereas the special modifier with coupling agent enhances their compatibility with the bulk. The mechanical, oil resistance, and thermal properties of the composites are greatly reinforced by clay-networks which parallel their interactions. Importantly, the addition of clays barely changes glassy temperature (Tg) of rubber bulk, but it improves its low-temperature elasticity. Therefore, it is stressed that organoclay hybrid networks are very useful to modify low-temperature rubber. We believe that LTG-HNBR composites with organoclays may serve some applications of oil-sealing products. POLYM. COMPOS., 35:1306–1317, 2014. © 2013 Society of Plastics Engineers
Co-reporter:Jihua Zhang, Lifeng Wang, Yunfeng Zhao
Materials & Design 2013 50() pp: 322-331
Publication Date(Web):
DOI:10.1016/j.matdes.2013.02.072
Co-reporter:Jihua Zhang, Lifeng Wang, Yunfeng Zhao
Materials & Design 2013 51() pp: 648-657
Publication Date(Web):
DOI:10.1016/j.matdes.2013.04.073
Co-reporter:Jihua Zhang;Lifeng Wang ;Yunfeng Zhao
Polymer Composites 2012 Volume 33( Issue 12) pp:2125-2133
Publication Date(Web):
DOI:10.1002/pc.22352
Abstract
To overcome the modification shortcoming of phenol resin (PR) in decreasing the loss factor peak (tan δmax) of nitrile butadiene rubber (PR/NBR) blends, the hindered phenol AO-80/PR/NBR hybrids were successfully prepared. The tan δmax of the hybrids is found to increase with the increment of AO-80 content while they almost remains the same widths of damping temperature range as PR/NBR blend. Their damping properties can be regulated well by controlling the content of AO-80. Various experimental data of Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, and dynamic viscoelastic measurements (DMAs) show that the good damping properties of the hybrids result from the cooperative effect of two different relaxation transitions: the hydrogen bonds of nitrile group associated with hydroxyl group of AO-80 besides their glass transition. The effect does not decrease the width of damping temperature range of the hybrids but really maintain a high value of tan δmax in a long duration; but it is found that the components of hybrids with the high content of AO-80 become partly compatible after long-period storage. So the content of AO-80 is important to sustain the damping storage stability for NBR hybrids where the amount of AO-80 below 50 phr is preferred. We believe that our studies provide some basic observations to serve the practical applications of NBR hybrids. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Co-reporter:Xianliang Sheng and Jihua Zhang
Langmuir 2009 Volume 25(Issue 12) pp:6916-6922
Publication Date(Web):March 27, 2009
DOI:10.1021/la9002077
In this article, nanostructured superhydrophobic polymeric surfaces were fabricated by a simple (one-step) reproductive method of anodic aluminum oxide (AAO) template extrusion. By tuning the diameter of the AAO template and the pressure to extrude, high-density polyethylene (HDPE) nanofiber surfaces with different nanometer roughness were prepared, and various sliding angles (SAs) of drops on these surfaces were measured. The results of the impact of drops on the nanostructured HDPE surfaces indicated that SAs were very important for the dynamic wettability of superhydrophobic surfaces. The one-step AAO template extrusion method has the advantage of tailoring the SA values on polymeric surfaces. Therefore, we believe it to be a promising industrial basis for manufacturing functional materials in the fields of agriculture, electronics, and optics.
Co-reporter:Jihua Zhang, Xianliang Sheng and Lei Jiang
Langmuir 2009 Volume 25(Issue 3) pp:1371-1376
Publication Date(Web):December 24, 2008
DOI:10.1021/la8024233
The high dewetting abilities of lotus leaves can be transited to a complete wetting state by soaking the leaves in water at a depth of 50 cm for 2 h. However, after being dried by N2 gas, the high dewetting behavior of lotus leaves may be mostly restored. This indicates that experimental procedure might considerably affect the dewetting abilities of lotus leaves. To discover the mechanism underlying this interesting dewetting phenomena, the dewetting force was used to characterize the dewetting abilities of surfaces, and model studies to mimic the papillae were done. Surface hydrophobicity, sizes, rise angles, and secondary structures of the models’ sides affected their dewetting force with water. So we suggested that the dewetting states, Cassie or Wenzel’s state, of lotus surfaces depend much on the depth of water, i.e., the hydraulic pressure. On the other hand, the primary structures of papillae in Cassie’s state led to a high receding angle with respect to the plane of the leaf during the dewetting measurement. The secondary structures and micro/nano arrays of papillae increased the dewetting abilities of lotus leaves, since no water intruded between papillae. However, the structures of papillae in Wenzle’s state significantly reduced the dewetting abilities of lotus leaves after being soaked at a depth of 50 cm for 2 h. Therefore, as for novel designs of microdevices floating on water, including the use of the high dewetting properties of suphydrophobic materials, surface (primary or secondary) microstructure and external pressure, such as static hydraulic pressure, must be taken into account.
Co-reporter:Xianliang Sheng, Jihua Zhang and Lei Jiang
Langmuir 2009 Volume 25(Issue 17) pp:9903-9907
Publication Date(Web):June 5, 2009
DOI:10.1021/la901058y
In this article, a simple method of pressing a conical frustum into liquid was adopted to explore the ability to restrict flow around their edges. On the basis of experiments and theoretical analyses, the restricting force Δf and the pressing work ΔEw were used to characterize the ability to restrict flow around the edge for water or formamide, which were found to be closely related to the geometric morphologies of edges and the liquid and material characteristics. The ability to restrict flow around the edge may be enhanced by increasing the rise angle ω and the size of edge circles and using a high-surface-energy liquid. Inspired by this, the superhydrophobicity of the materials with lower hydrophobicity has been successfully obtained by constructing close microedges on their flat surfaces. We believe that these findings would help to widen several novel applications to high-adhesion superhydrophobic surfaces.
