Mechanical properties, and glass transition temperature

Polyurethane-acrylic coatings with interpenetrating polymer networks (IPNs) were synthesized from a two-component polyurethane (PU) and an unsaturated urethane-modified acrylic copolymer. The two-component PU was prepared from hydroxyethylacrylate-butylmethacrylate copolymer with or without reacting with c-caprolactonc and cured with an aliphatic polyisocyanate. The unsaturated acrylic copolymer was made from the same hydroxy-functional acrylic copolymer modified with isocyanatoethyl methacrylate. IPNs were prepared simultaneously from the two-polymer systems at various ratios. The IPNs were characterized by their mechanical properties and glass transition temperatures. 

Sakellariou, P. Rowe, R.C. White, E.F.T. The thermo-mechanical properties and glass transition temperatures of some cellulose derivatives. Int. J. Pharm. 1985, 27,... 

In general, the mechanical properties and glass transition temperature are reported to be enhanced in the presence of CNTs. A practical method of producing CNT-polymer composites is by melt mixing. For this purpose, the goal of this study was to prepare SWNT-polymer composites by melt mixing using a shear mixer. 

All polymers are susceptible to the absorbtion of moisture. In general this results in a reduction in mechanical properties and glass transition temperature. 

In the previous chapter, it was pointed out how the chemical structure of polymers influences their mechanical properties. The glass transition temperature and the rate of cooling from the melt determine whether the polymer will be a hard, stiff material, or a soft flexible material. These qualitative differences can be quantifled by measuring standard mechanical properties. The student, generally, is introduced to the subject of mechanical behavior through the study of linear elastic metals that exhibit solid behavior at normal operating temperatures and conditions. However, this study of polymers reveals that polymers exhibit fluid as well as solid behavior and are viscoelastic and viscoplastic at room temperature. The mechanical properties of polymers are strain rate sensitive and highly temperature dependent. 

Most PHAs are partially crystalline polymers and therefore their thermal and mechanical properties are usually represented in terms of the glass-to-rubber transition temperature (Tg) of the amorphous phase and the melting temperature (Tm) of the crystalline phase of the material [55]. The melting temperature and glass transition temperature of several saturated and unsaturated PHAs have been summarized in Table 2. 

Fluorinated poly(imide-ether-amide)s are readily soluble in organic solvents like dimethylformamide (DMF), N-methylpyrrolidone (NMP), pyridine or tetrahydrofu-ran (THF) and give flexible films by casting of such solutions. These polymers exhibit decomposition temperatures above 360°C, and glass transition temperatures in the 221-246° C range. The polymer films have a low dielectric constant and tough mechanical properties. 

The improvement of damage resistance and tolerance in interlaminar fracture and under impact loading for the toughened matrix composites is at the expense of other important mechanical properties, such as inferior stiffness and hot/wet compressive strength (Evans and Masters, 1987). These trade offs appear to be associated with the reduction in matrix modulus and glass transition temperature (Jordan et al., 1989). 

The simplest dependency exists between composition and glass transition temperature Independent from the ratio A/B one finds two values for Tg, one for the block from monomer A and one for the block of B. More complex are the dependencies with the mechanical properties. Here, parameters like the ratio A/B, number of blocks, block length, and alternation of the blocks play a decisive role. This is shown in Examples 3-47 and 3-48 with triblock copolymers of buta-... 

Regarding the properties required of the solidified materials in 2D printing, the most important properties are generally related to thin material layers, such as color, adhesion to the substrate, hghtfastness, and scratch resistance, whereas in 3D printing, the most important properties are generally related to the bulk material mechanical and thermomechanical properties, for example tensile and flexural properties, impact resistance, and Glass Transition Temperature (Tg). 

Microwave-assisted curing of epoxy resin systems was one of the first applications of MW in polymer chemistry and is the most widely studied area in polymer chemistry under both continuous and pulse microwave conditions. The structure, dielectric properties, toughness, mechanical strength, percentage of cure, and glass transition temperature of the epoxy formulations have been investigated [1]. 

Plastics - Thermomechanical analysis (TMA) - Determination of linear thermal expansion coefficient and glass transition temperature Plastics - Thermomechanical analysis (TMA) - Determination of softening temperature Plastics - Determination of dynamic mechanical properties -General principles Plastics - Dynamic mechanical analysis - Determination of glass transition temperature Plastics - Dynamic mechanical analysis - Calibration... 

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