A facile approach to the scalable preparation of thermoplastic/carbon nanotube composites.

Disentangling and dispersing multiwalled carbon nanotubes (MWCNTs) in thermoplastics by the existing melt compounding facilities where neither solvent nor liquid chemicals are allowed remains a great challenge. This challenge is addressed herein by combining ball milling with melt compounding. Specifically, ball milling is applied to disentangle MWCNTs and to eventually liberate each tube from agglomeration, and then the tubes are melt compounded with SSFs (PA6). A uniformly distributed MWCNT network is observed; obvious load transfer from the matrix to the tubes is evidenced by the presence of many firmly embedded tubes on the fracture surface. The electrical conductivity percolation threshold of PA6/MWCNT composites is found to be 2.5-3.0 wt%, in comparison with 5.0-8.0 wt% for PA6/stainless steel fiber composites. The PA6/MWCNT composite at 10.0 wt% shows a 76% increase in flexural modulus and 58% in flexural strength.

Graphene platelets versus phosphorus compounds for elastomeric composites: flame retardancy, mechanical performance and mechanisms.

Polymers are widely used but their flammability remains a serious issue causing fatalities and property damage. Herein we present an investigation into the effectiveness of graphene platelets (GnPs) to simultaneously improve the flame retardancy and mechanical properties of ethylene propylene diene monomer rubber (EPDM). EPDM was melt compounded respectively with GnPs and a commercial flame retardant (ammonium polyphosphate, APP) to produce two groups of composites. Although both fillers were well dispersed in EPDM, GnPs significantly improved the mechanical properties of EPDM whilst APP compromised some of the mechanical properties particularly at high fractions. This difference was attributed to the filler particle size and interfacial bonding. Through cone calorimetry testing, 21 wt% char yield was recorded for the EPDM/GnP composite at 12.0 vol%, in comparison with 8 wt% for the EPDM/APP composite. APP was able to lower the peak heat release rate (PHRR) and specific mass loss rate (MLR), but unfortunately it decreased the ignition time and fire performance index (FPI). By contrast, GnPs has been found to increase ignition time by 29% and FPI by 62%, while still achieved the same level of reductions in PHRR and specific MLR, demonstrating clear advantages over APP. During combustion the highly thermally stable GnPs bonded with the viscous, degraded EPDM macromolecules, forming a thick solid char layer which prevented the transport of heat and smoke, contributing to its superior flame retarding performance over APP.

Improving Thermal Stability of Polyurethane through the Addition of Hyperbranched Polysiloxane.

Polydimethylsiloxane with hydroxy groups was functionalized to form functionalized polydimethylsiloxane, which subsequently underwent an addition reaction with isophorone diisocyanate to form the prepolymer. Next, 3-aminopropyltriethoxysilane (APTS) reacted with 3-glycidoxypropyltrimethoxysilane (GPTS) to produce bridged polysilsesquioxanes, and sol-gel technology was employed to form hyperbranched polysiloxane nanoparticles with hydroxy groups, APTS-GPTS, which was used as the additive. The hyperbranched polysiloxane and the prepolymer containing NCO functional groups then underwent an addition reaction to produce the hybrid materials. Fourier-transform infrared spectroscopy and 29Si nuclear magnetic resonance were used to characterize the structure of the polyurethane hybrid. Regarding thermal stability, after the hyperbranched polysiloxane nanoparticles was introduced, the integral procedural decomposition temperature increased from 348 °C for polyurethane matrix to 859 °C for the hybrid material. The results reveal that the thermal stability of the hybrid material substantially increased by approximately 247%.

Preparation and Flame Retardance of Polyurethane Composites Containing Microencapsulated Melamine Polyphosphate.

A new microencapsulated flame retardant containing melamine polyphosphate (MPP) and 4,4'-oxydianiline-formaldehyde (OF) resin as the core and shell materials, respectively, was synthesized by in situ polymerization. 29Si NMR was used to measure the condensation density of polyurethane containing silicon compound (Si-PU). The structures and properties of the microencapsulated melamine polyphosphate (OFMPP) were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy and water solubility. Thermal behavior of the OFMPP was systematically analyzed through thermogravimetric analysis. Flame retardance tests such as the limiting oxygen index and UL-94 were employed to evaluate the effect of composition variation on the MPP and OFMPP in polyurethane composites. The results indicated that the microencapsulation of MPP with the OF resin improved hydrophobicity and that the flame retardance of the Si-PU/OFMPP composite (limiting oxygen index, LOI = 32%) was higher than that of the Si-PU/MPP composite (LOI = 27%) at the same additive loading (30 wt %).

PEDOT-based composites as electrode materials for supercapacitors.

Poly (3, 4-ethylenedioxythiophene) (denoted PEDOT) already has a brief history of being used as an active material in supercapacitors. It has many advantages such as low-cost, flexibility, and good electrical conductivity and pseudocapacitance. However, the major drawback is low stability, which means an obvious capacitance drop after a certain number of charge-discharge cycles. Another disadvantage is its limited capacitance and this becomes an issue for industrial applications. To solve these problems, there are several approaches including the addition of conducting nanofillers to increase conductivity, and mixing or depositing metal oxide to enhance capacitance. Furthermore, expanding the surface area of PEDOT is one of the main methods to improve its performance in energy storage applications through special processes; for example using a three-dimensional substrate or preparing PEDOT aerogel through freeze drying. This paper reviews recent techniques and outcomes of PEDOT based composites for supercapacitors, as well as detailed calculations about capacitances. Finally, this paper outlines the new direction and recent challenges of PEDOT based composites for supercapacitor applications.

Facile Fabrication of Graphene Membranes with Readily Tunable Structures.

Advanced membranes that combine mechanical robustness with fast permeation are crucial to many applications such as water purification, ions selectivity, and gas separation. Graphene sheets offer a promising opportunity to fabricate thin, high-flux, and pressure-endurable membranes because of their unique 2D morphology, oxidizable surface, and electrical conductivity. We herein report a highly effective yet simple approach to the fabrication of graphene membranes featuring controllable oxidation degrees and thus tunable structures and properties. The graphene sheets comprise a single or a few layers with a lateral dimension of 50-100 nm; their C/O ratios can be manipulated from 4.1 for graphene with a low degree of oxidation (low-oxidation graphene) to 2.5 for medium-oxidation graphene to 1.3 for high-oxidation graphene, by controlling the proportion of phosphoric acid during the 60 min fabrication. Fabricated by simple vacuum filtration, the membranes exhibited various water flux from 200.0 to 20.0 L/m(2)·h·bar at 3 bar of pressure and mechanical robustness (Young's modulus can be up to 20 GPa and tensile strength to 100 MPa). When these membranes were used as electrodes for supercapacitors, specific capacitances of 58.8 F/g and 23.5 F/cm(3) were recorded for the low-oxidation graphene membrane at 1 A/g by a two-electrode configuration; the capacity values retained ∼95% after 800 cycles; the high capacitance would be caused by moderate wettability and high electrical conductivity.

A new approach to integrate Internet-of-things and software-as-a-service model for logistic systems: a case study.

Cloud computing is changing the ways software is developed and managed in enterprises, which is changing the way of doing business in that dynamically scalable and virtualized resources are regarded as services over the Internet. Traditional manufacturing systems such as supply chain management (SCM), customer relationship management (CRM), and enterprise resource planning (ERP) are often developed case by case. However, effective collaboration between different systems, platforms, programming languages, and interfaces has been suggested by researchers. In cloud-computing-based systems, distributed resources are encapsulated into cloud services and centrally managed, which allows high automation, flexibility, fast provision, and ease of integration at low cost. The integration between physical resources and cloud services can be improved by combining Internet of things (IoT) technology and Software-as-a-Service (SaaS) technology. This study proposes a new approach for developing cloud-based manufacturing systems based on a four-layer SaaS model. There are three main contributions of this paper: (1) enterprises can develop their own cloud-based logistic management information systems based on the approach proposed in this paper; (2) a case study based on literature reviews with experimental results is proposed to verify that the system performance is remarkable; (3) challenges encountered and feedback collected from T Company in the case study are discussed in this paper for the purpose of enterprise deployment.

Processable 3-nm thick graphene platelets of high electrical conductivity and their epoxy composites.

Graphene platelets (GnPs) are a class of novel 2D nanomaterials owing to their very small thickness (∼3 nm), high mechanical strength and electric conductivity (1460 S cm(-1)), and good compatibility with most polymers as well as cost-effectiveness. In this paper we present a low-cost processing technique for producing modified GnPs and an investigation of the electrical and mechanical properties of the resulting composites. After dispersing GnPs in solvent N-methyl-2-pyrrolidone, a long-chain surfactant (Jeffamine D 2000, denoted J2000) was added to covalently modify GnPs, yielding J2000-GnPs. By adjusting the ratio of GnPs to the solvent, the modified GnPs show different average thickness and thus electrical conductivity ranging from 694 to 1200 S cm(-1). To promote the exfoliation and dispersion of J2000-GnPs in a polymeric matrix, they were dispersed in the solvent again and further modified using diglycidyl ether of bisphenol A (DGEBA) producing m-GnPs, which were then compounded with an epoxy resin for the development of epoxy/m-GnP composites. A percolation threshold of electrical volume resistivity for the resulting composites was observed at 0.31 vol%. It was found that epoxy/m-GnP composites demonstrated far better mechanical properties than those of unmodified GnPs of the same volume fraction. For example, m-GnPs at 0.25 vol% increased the fracture energy release rate G1c from 0.204 ± 0.03 to 1.422 ± 0.24 kJ m(-2), while the same fraction of unmodified GnPs increased G1c to 1.01 ± 0.24 kJ m(-2). The interface modification also enhanced the glass transition temperature of neat epoxy from 58.9 to 73.8 °C.

Multiple-parameter evaluation demonstrates low donor-site morbidity after submental flap harvesting.

PURPOSE: The objective of this study was to implement a scoring system to analyze the authors' experience of donor-site morbidity after harvesting a submental flap for the reconstruction of surgical defects at the head and neck region after oncologic resection. MATERIALS AND METHODS: A retrospective case series study was conducted of patients who underwent reconstruction with a submental flap at the Tri-Service General Hospital (Taipei, Taiwan) from 2008 through 2012. Five parameters representing donor-site morbidity (whistling, smiling, neck extension, beard change, and esthetic outcome) were evaluated with a scoring system developed by a blinded panel of 2 clinicians and the patients. Scores were analyzed and compared between patient subgroups. RESULTS: Twenty-two patients (20 men and 2 women; mean age, 56 yr) underwent reconstruction with a submental flap after head and neck tumor ablation. Primary lesion sites included the oral cavity (13 patients), pharynx (6 patients), larynx (1 patient), neck (1 patient), and sinus (1 patient). The means of all 5 parameters evaluated were higher than 8 on a scale of 0 to 9 (whistling, 8.7; smiling, 8.7; beard change, 8.9; neck extension, 8.2; esthetic outcome, 8.2), showing that submental flap harvesting led to low donor-site morbidity. CONCLUSIONS: Donor-site morbidity after submental flap harvesting was evaluated with a scoring system measuring 5 parameters, namely whistling, smiling, beard change, neck extension, and esthetic outcome. In general, donor-site morbidity was very low. This implemented system and these findings will be helpful in future reconstructive surgical planning and management.

Melt compounding with graphene to develop functional, high-performance elastomers.

Rather than using graphene oxide, which is limited by a high defect concentration and cost due to oxidation and reduction, we adopted cost-effective, 3.56 nm thick graphene platelets (GnPs) of high structural integrity to melt compound with an elastomer-ethylene-propylene-diene monomer rubber (EPDM)-using an industrial facility. An elastomer is an amorphous, chemically crosslinked polymer generally having rather low modulus and fracture strength but high fracture strain in comparison with other materials; and upon removal of loading, it is able to return to its original geometry, immediately and completely. It was found that most GnPs dispersed uniformly in the elastomer matrix, although some did form clusters. A percolation threshold of electrical conductivity at 18 vol% GnPs was observed and the elastomer thermal conductivity increased by 417% at 45 vol% GnPs. The modulus and tensile strength increased by 710% and 404% at 26.7 vol% GnPs, respectively. The modulus improvement agrees well with the Guth and Halpin-Tsai models. The reinforcing effect of GnPs was compared with silicate layers and carbon nanotube. Our simple fabrication would prolong the service life of elastomeric products used in dynamic loading, thus reducing thermosetting waste in the environment.

From carbon nanotubes and silicate layers to graphene platelets for polymer nanocomposites.

In spite of extensive studies conducted on carbon nanotubes and silicate layers for their polymer-based nanocomposites, the rise of graphene now provides a more promising candidate due to its exceptionally high mechanical performance and electrical and thermal conductivities. The present study developed a facile approach to fabricate epoxy-graphene nanocomposites by thermally expanding a commercial product followed by ultrasonication and solution-compounding with epoxy, and investigated their morphologies, mechanical properties, electrical conductivity and thermal mechanical behaviour. Graphene platelets (GnPs) of 3.57 ± 0.50 nm in thickness were created after the expanded product was dispersed in tetrahydrofuran using 60 min ultrasonication. Since epoxy resins cured by various hardeners are widely used in industries, we chose two common hardeners: polyoxypropylene (J230) and 4,4'-diaminodiphenylsulfone (DDS). DDS-cured nanocomposites showed a better dispersion and exfoliation of GnPs, a higher improvement (573%) in fracture energy release rate and a lower percolation threshold (0.612 vol%) for electrical conductivity, because DDS contains benzene groups which create π-π interactions with GnPs promoting a higher degree of dispersion and exfoliation of GnPs during curing. This research pointed out a potential trend where GnPs would replace carbon nanotubes and silicate layers for many applications of polymer nanocomposites.

Head and neck cancers manifested as deep neck infection.

The incidence of head and neck cancers in patients with an initial presentation of deep neck infection is unclear and may be underestimated. Thus, the aim of this study was to assess the incidence of head and neck cancers initially manifested as deep neck infection. Also, the possible risk factors and pathophysiology are discussed. This study was a retrospective medical chart review in a tertiary referral center. A total of 81 consecutive patients admitted with a diagnosis of deep neck infection over a 46-month period were analyzed. The demographic data, physical examinations, laboratory findings, radiographic studies, and pathology report were analyzed. Among the 81 deep neck infection patients, head and neck cancers were histologically demonstrated in four patients (4.9%) with the initial symptom of a painful neck mass. The incidence of head and neck cancer initially manifested as deep neck infection was found to increase in patients aged over 40 years (6.7%; 3/45 vs. 2.8%; 1/36). A detailed history of all patients with deep neck infection should be taken. Furthermore, endoscopic examination, thyroid examination and routine pathological examination should be performed, especially in those aged over 40. Also, careful explanation to the patient and his/her family about the possibility of underlying head and neck cancer (incidence 1-5%) may be needed. If the neck swelling diminishes, but does not disappear completely after full course of antibiotics, repeated fine needle aspiration, endoscopy, or image study should be considered.

Twisted nose: a new simple classification and surgical algorithm in Asians.

The purpose of this study was to present our experiences with correction of twisted nose in Asian patients using a new and simple classification and a surgical algorithm. A classification and standard surgical algorithm was followed to determine treatment strategies for 384 patients with twisted nose between June 2001 and July 2009. A retrospective chart review from the Tri-Service General Hospital archives was performed to collect patients' data and surgical details. A follow-up self-evaluation survey regarding satisfaction with nasal function and esthetics was distributed to all participants. Preoperative and postoperative standardized photography of the face were evaluated to judge objectively the esthetic outcomes of the surgery. There were 147, 131, and 106 patients in Type I, Type II, and Type III patients, respectively. The percentages of functionally satisfied and very satisfied patients were 95.2, 93.9, and 93.4% in Type I, Type II, and Type III groups, respectively. The percentages of esthetically satisfied or very satisfied patients were 89.1, 88.5, and 87.7% in Type I, Type II, and Type III groups, respectively. There were only 2 patients with type III deviation with residual deviation of dorsum objectively who were satisfied with the results after undergoing a revision rhinoplasty. Aside from residual deviation, the postoperative periods were uneventful and without major complications. We propose a new and simple classification and surgical algorithm to optimally correct twisted nose deformities for Asian patients. The classification and surgical algorithm, which is simple and reproducible especially for beginner, guides surgical decisions that yield consistently satisfactory functional and esthetic results.

Endoscopic transsphenoidal vidian neurectomy.

The purpose of this report is to describe a novel technique for endoscopic vidian neurectomy (EVN) based on preoperative computed tomography (CT) classification of the vidian canal (VC), and to present anatomical and surgical findings from an initial series. Retrospective study, consisting of medical chart review and patient interviews, of all preoperative CT-guided EVN procedures was performed from 2006 to 2010 at a tertiary-care medical center. A total of 89 patients with intractable rhinorrhea (77 males and 12 females, mean age 29 years, age range 16-57 years) underwent bilateral EVN. Configuration of the VC was classified into three types based on preoperative CT findings. The technique for surgical access of each of these configurations is presented. The most common configuration of the VC was type 2 (47%). A wide, direct, and safe exposure of the vidian nerve was achieved in all cases. 84 of 89 patients completed the questionnaires regarding the postoperative improvement in quality of life. Follow-up ranged from 2 to 42 months, with an average of 19.6 months. 77 of 84 (91.7%) patients were satisfied with their surgical result. Two patients underwent revision ETSVN due to relapsed symptoms. With the help of a preoperative CT scan of the paranasal sinuses, the vidian nerve can be identified precisely via an endoscopic intrasphenoidal or transsphenoidal approach, which provides an easy and reliable way to perform vidian neurectomy.