TDI System Research Articles

Ag immobilized lignin-based PU coating: A promising candidate to promote the mechanical properties, thermal stability, and antibacterial property of paper packaging

A lignin-based PU coating was prepared for paper-based green packaging. Two representative diisocyanate were used to prepare the coatings. Due to the rigid aromatic, the physical properties of the TDI system reached the maximum below the lignin content of 40%. The HDI that contains flexible aliphatic chains alleviated the brittleness of coating, and it showed physical advantages when the lignin content was more than 50%. Owing to the high lignin content, the coating presented enhanced thermal stability. After coated with the lignin-based PU coatings, the dry tensile strength of coated paper was improved by 126%. Amazingly, the wet strength was increased from 0.31 to 12.6 MPa with an improvement nearly 40 times. Based on the coordination of lignin, Ag+ was introduced into the PU matrix, which imparted the coating with excellent antibacterial ability. The colony forming units of E. coli and S. aureus were both less than 1. However, no inhibition halo was observed, which indicated that the Ag was firmly anchored on the coating and the antibacterial ability is only available when the bacterial contact the coating surface. The lignin-based PU coating with favorable sustainability and properties shows great potential in paper-based green packaging fields.

The b‐bibranching problem: TDI system, packing, and discrete convexity

AbstractIn this article, we introduce the b‐bibranching problem in digraphs, which is a common generalization of the bibranching and b‐branching problems. The bibranching problem, introduced by Schrijver, is a common generalization of the branching and bipartite edge cover problems. Previous results on bibranchings include polynomial algorithms, a linear programming formulation with total dual integrality, a packing theorem, and an M‐convex submodular flow formulation. The b‐branching problem, recently introduced by Kakimura, Kamiyama, and Takazawa, is a generalization of the branching problem admitting higher indegree, that is, each vertex v can have indegree at most b(v). For b‐branchings, a combinatorial algorithm, a linear programming formulation with total dual integrality, and a packing theorem for branchings are extended. A main contribution of this article is to extend those previous results on bibranchings and b‐branchings to b‐bibranchings. That is, we present a linear programming formulation with total dual integrality, a packing theorem, and an M‐convex submodular flow formulation for b‐bibranchings. In particular, the linear program and M‐convex submodular flow formulations, respectively, imply polynomial algorithms for finding a shortest b‐bibranching.

Recognizing conic TDI systems is hard

In this note we prove that the problem of deciding whether or not a set of integer vectors forms a Hilbert basis is co-NP-complete. Equivalently, deciding whether a conic linear system is totally dual integral or not, is co-NP-complete. These statements are true even if the vectors in the set or respectively the coefficient vectors of the inequalities are 0–1 vectors having at most three ones.

Algebraic and combinatorial properties of ideals and algebras of uniform clutters of TDI systems

Let $\mathcal{C}$ be a uniform clutter and let A be the incidence matrix of $\mathcal{C}$ . We denote the column vectors of A by v 1,…,v q . Under certain conditions we prove that $\mathcal{C}$ is vertex critical. If $\mathcal{C}$ satisfies the max-flow min-cut property, we prove that A diagonalizes over ℤ to an identity matrix and that v 1,…,v q form a Hilbert basis. We also prove that if $\mathcal{C}$ has a perfect matching such that $\mathcal{C}$ has the packing property and its vertex covering number is equal to 2, then A diagonalizes over ℤ to an identity matrix. If A is a balanced matrix we prove that any regular triangulation of the cone generated by v 1,…,v q is unimodular. Some examples are presented to show that our results only hold for uniform clutters. These results are closely related to certain algebraic properties, such as the normality or torsion-freeness, of blowup algebras of edge ideals and to finitely generated abelian groups. They are also related to the theory of Gröbner bases of toric ideals and to Ehrhart rings.

Rheokinetic modeling of HTPB–TDI and HTPB–DOA–TDI systems

AbstractA study of the effect of temperature on a mixture of polymer and curative in the processing of rocket propellants is reported. Experimental viscosity of a hydroxyl‐terminated polybutadiene–toluene diisocyanate (HTPB–TDI) system was measured using a Brookfield viscometer model DV III. Viscosity showed dependence on temperature as well as time. The viscosity data of the HTPB–TDI system showed a linear relationship with temperature, with a change in slope at 45°C. The time dependence model showed a fourth‐order curve fit, which gave better results over the exponential model fit. The activation energy required for flow of the HTPB–TDI system was found to be 15.5 kJ/mol. Experimental viscosity measurements at various temperatures was also carried out on a hydroxyl‐terminated polybutadiene–dioctyl adipate –toluene diisocyanate (HTPB–DOA–TDI) system. The temperature dependence showed a decrease in viscosity with an increase in temperature up to 60 min, beyond which the viscosity increased. Viscosity showed a linear relation with temperature, with a change in the slope at 50°C instead of at 45°C for HTPB–TDI system. Beyond 50°C the data followed a polynomial model similar to that of the HTPB–TDI system, and the results matched well with the experimental data. The activation energy of the HTPB–DOA–TDI system increased with an increase in the binder weight ratio. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1331–1335, 2003

Gomory integer programs

The set of all group relaxations of an integer program contains certain special members called Gomory relaxations. A family of integer programs with a fixed coefficient matrix and cost vector but varying right hand sides is a Gomory family if every program in the family can be solved by one of its Gomory relaxations. In this paper, we characterize Gomory families. Every TDI system gives a Gomory family, and we construct Gomory families from matrices whose columns form a Hilbert basis for the cone they generate. The existence of Gomory families is related to the Hilbert covering problems that arose from the conjectures of Sebo. Connections to commutative algebra are outlined at the end.

Minimum T-cuts and optimal T-pairings

We introduce the notion of T-pairing and give a min–max characterization for the minimum size of a T-cut. We show that the coefficients in the minimal TDI system for the T-cut polyhedron can be arbitrarily big.

Color-coded measures of myocardial velocity throughout the cardiac cycle by tissue Doppler imaging to quantify regional left ventricular function

TDI is a new echocardiographic technique that calculates and displays color-coded myocardial velocity on-line. To determine the feasibility of endocardial velocity throughout the cardiac cycle as a means to quantify regional function, 20 normal subjects aged 30 ± 5 years and 12 patients with heart disease aged 62 ± 17 years were studied with a prototype TDI system. TDI M-mode images were acquired by using a multicolored velocity map (display range, −30 to 30 mm/sec; temporal resolution, 90 Hz). Color-coded velocity data were then converted to numeric values off-line at 50 msec intervals. Posterior wall velocities throughout the cardiac cycle by TDI were closely correlated with velocity calculations from the first derivative of routine digitized M-mode tracings (group mean r = 0.88 ± 0.03, SEE = 7.0 ± 1.1 mm/sec). Anteroseptal TDI color-coded systolic velocity occurred 164 ± 84 msec from the onset of the electrocardiographic QRS compared with 203 ± 33 msec in the posterior wall ( p < 0.05) in normal subjects, consistent with normal electrical activation. Significant differences in systolic and diastolic posterior wall TDI velocity data were observed in patients with hypokinetic or akinetic segments assessed by independent routine study when compared with normal controls. Calculated systolic and early diastolic posterior wall TDI indexes correlated significantly with percentage of wall thickening. Of abnormal anteroseptal segments, TDI systolic time velocity integrals were significantly different than normal and correlated with percentage of wall thickening. TDI has potential to quantitatively assess regional left ventricular function.

Digital signal processor based digital time delay integration for a medical infrared imaging system

ownloaded From: http://opticalengineering.spiedigitallibrary.org/ on 09/01/2016 through the first in first outs ~FIFOs!. It also directs the timer to generate proper timing signals for data sampling and time delaying. The horizontal synchronizing signal generated by the optic scanner is fed to the programmable timer to initiate data samplings in each scan line. The sampled data are stored in the internal RAM of the ADSP2111 and added up after a proper time delay. Through a FIFO, the processed data in the DSP are transmitted to the main computer in which the image data can be displayed and analyzed. In our study, a personal computer ~486DX, 66 MHz! was used as a main computer. The digital TDI system was attached to a homemade two-dimensional infrared scanner. The infrared scanner is composed of an oscillating mirror mounted on a galvanometer for vertical scanning, and a polygon mirror mounted on a DC brushless motor for horizontal scanning. The number of horizontal data points and vertical scan lines were 256 and 240, respectively, so that the image can easily be displayed in a PC-VGA monitor. The infrared scanner’s field of view is 20 deg both horizontally and vertically. The afocal system of the infrared scanner is made of antireflection-coated germanium lenses with a magnification power of 1.8. The aperture diameter of the afocal system is 26 mm. The output beam diameter of the afocal system is 13 mm. The oscillating frequency of the vertical scan mirror is between 4 and 16 Hz and the rotating speed of the polygon mirror is set to 9,000 rpm. The polygon mirror has eight facets with an inscribed diameter of 65 mm and a thickness of 13 mm. The infrared detector has 4 elements, each measuring 100380 mm. The elements are lined up with 15-mm spacing. The specific detectivities of the detector elements range from 4 to 5310 cm Hz W. The imaging signals from the detector elements are digitized with a sampling time of 1.9 ms. The DSP stores the digitized signals in its memory and adds up the signals with proper delays. In addition to the usual signal processings aforementioned, the DSP also corrects cosu shading artifacts, where u is the scan angle in relation to the

Polyurethane cationomers III: Oxygen permeation

AbstractDynamic oxygen permeation measurements at 20–70°C on films cast from solutions and emulsions of three series of polyurethane (PU) cationomers based on MDI, HDI, and TDI that are the subject of Parts I and II of this series were made by Barrer's vacuum technique. For the MDI system, films cast from solutions of ionized PU exhibit permeation coefficients P that are higher at 20–40°C (below the glass transition temperature Tgh of the hard domains) than at 50–70°C (above Tgh) by factors of about 5 and 40. This is the opposite of what is observed for normal homopolymers and un‐ionized PU. This phenomenon is attributed to the continuous/dispersed morphology of these films. At the low temperature, oxygen molecules diffuse through the continuous phase (soft domains) only. But at the high temperature, oxygen molecules diffuse through soft domains and subsequently through hard domains, leading to an increase in diffusion pathlength. For films cast from the PU emulsions, such a drop in P was not observed because the hard domains were partially inverted from the dispersed phase to a continuous phase that gives an interwoven morphology. Such morphology allows oxygen molecules to diffuse through soft and phase‐inverted hard domains simultaneously. For the HDI and TDI systems, P and D vs. 1/T plots show no zone of discontinuity. This is attributed to a Tgh that is lower than or close to the permeation temperature. © 1995 John Wiley &amp; Sons, Inc.

Lattice matrices, intersection of ring families and dicuts

Lattice matrices are 0/1-matrices used in the description of certain lattice polyhedra and related to dicuts in a graph. The incidence matrix A I of a so-called intersection of two ring families and the incidence matrix A D of all dicuts of a graph are examples of such matrices. After showing that any lattice matrix A can be obtained from some matrix A I by deletion or some A D by contraction, we first describe the convex hull of the rows of A I, CONV( A I), as the solution set of a system x⩾0, Bx⩽1, Rx⩽0, which is tdi. We then derive the main result, the description of CONV( A) by another tdi system. As applications, the polyhedral description of all dicuts in a graph, CONV( A D), and that of all convex sets of bounded length in a poset are established.

The Effect of Castor Oil on the Structure and Properties of Polyurethane Elastohers (TDI System)

Abstract Segmented polyurethane elastomers, based on a mixture of castor oil and polypropylene glycol, toluene diisocyanate and 1,4-butanediol were prepared. The physical, thermal, dynamic mechanical behaviour, and x-ray diffraction have been studied. The use of castor oil shifts the main transition of the soft phase to higher temperature (glass transition temperature Tg increases), improves hardness, tensile strength, modulus and tear strength. Elongation and abrasion resistance decrease as ratio of castor oil increases. X- ray diffraction patterns show elastomers are amorphous. Trifunctionality of castor oil leads to the crosslinking of soft segments and a decrease of solubility and swelling of elastomers.

Polyurethane cationomers. II. Phase inversion and its effect on physical properties

AbstractThe three series of polyether polyurethane cationomers based on MDI, HDI, and TDI that are the subject of Part I, undergo emulsification (or phase inversion) on addition of water to solutions in MEK. The phase inversion mechanism depends on the structure of hard segment, ionic content, and dispersion temperature. The dispersion process can be divided into three stages involving a separation of hard segment aggregates due to adsorption of water on their surface, water entering into disordered and then ordered hard domains, and finally a rearrangement of agglomerates to form microspheres. The extent of penetration of water into the disordered hard domains decreases with increasing glass transition temperature; while in ordered hard domains, penetration depends on the dissociation temperature of urethane–urethane hydrogen bonds. Thus the penetration of water into the hard domains is strongly dependent on the dispersion temperature. Films cast from the emulsions have both ordered and disordered hard segment regions, this is also true of films cast directly from solution. The dispersion can disrupt the order in hard domains, leading to an increased phase separation for the MDI system and to a slightly increased phase mixing for the HDI and TDI systems. Films cast from solutions have a morphology with soft domains as a continuous phase and hard domains as a fibrillar network dispersed in the continuous phase. After dispersion, the hard segments originally distributed in the dispersed phase can be inverted to become a hard domain network or a continuous phase.

The Use of 2,6-Toluenediisocyanate in Polyurethane Cast Elastomers

A study of the use of 2,6-toluenediisocyanate (2,6-TDI) in polyurethanes was made by comparing polymers made with pure 2,6 TDI to an 80/20 isomeric blend of 2,4/2,6- TDI and to pure 2,4-TDI. Prepolymers were prepared using three different types of polyols [polybutylene adipate, polycaprolactone, and poly(oxytetramethylene) glycol] which were end-capped with the three TDI systems. These prepolymers were cured using three types of aromatic primary diamines (MBOCA, Polacure, and Cyanacure) and a hydroxyl system composed of a 4:1 blend (based on equivalents) of 1,4-butanediol with trimethylolpropane.

On switching paths polyhedra

A class of integer polyhedra with totally dual integral (tdi) systems is proposed, which generalizes and unifies the “Switching Paths Polyhedra” of Hoffman (introduced in his generalization of Max Flow-Min Cut) and such polyhedra as the convex hull of (the incidence vectors of) all “path-closed sets” of an acyclic digraph, or the convex hull of all sets partitionable intok path-closed sets. As an application, new min-max theorems concerning the mentioned sets are given. A general lemma on when a tdi system of inequalities is box tdi is also given and used.

On box totally dual integral polyhedra

Edmonds and Giles introduced the class of box totally dual integral polyhedra as a generalization of submodular flow polyhedra. In this paper a geometric characterization of these polyhedra is given. This geometric result is used to show that each TDI defining system for a box TDI polyhedron is in fact a box TDI system, that the class of box TDI polyhedra is in co-NP and is closed under taking projections and dominants, that the class of box perfect graphs is in co-NP, and a result of Edmonds and Giles which is related to the facets of box TDI polyhdera.