Thermal properties brittleness temperature

The relationship between the physical properties of profiles extruded from flexible PVC compounds and the extrusion melt temperature was studied. The properties included tear resistance, tensile properties, brittleness temperature and compression set. The effect of thermal history on surface characteristics of the extrudate, such as surface roughness and gloss, and the relationship of the latter with the processing morphology were also examined. An increase... 

Mechanical and Thermal Properties. The first member of the acrylate series, poly(methyl acrylate), has fltde or no tack at room temperature it is a tough, mbbery, and moderately hard polymer. Poly(ethyl acrylate) is more mbberflke, considerably softer, and more extensible. Poly(butyl acrylate) is softer stiU, and much tackier. This information is quantitatively summarized in Table 2 (41). In the alkyl acrylate series, the softness increases through n-octy acrylate. As the chain length is increased beyond n-octy side-chain crystallization occurs and the materials become brittle (42) poly( -hexadecyl acrylate) is hard and waxlike at room temperature but is soft and tacky above its softening point. 

T and are the glass-transition temperatures in K of the homopolymers and are the weight fractions of the comonomers (49). Because the glass-transition temperature is directly related to many other material properties, changes in T by copolymerization cause changes in other properties too. Polymer properties that depend on the glass-transition temperature include physical state, rate of thermal expansion, thermal properties, torsional modulus, refractive index, dissipation factor, brittle impact resistance, flow and heat distortion properties, and minimum film-forming temperature of polymer latex... 

The resin is too brittle to give a tme meaning to mechanical properties. The thermal properties are interesting in that there appears to be a transition point at 46°C. Above this temperature, specific heat and temperature coefficient of expansion are much greater than below it. The specific heat of hardened shellac at 50°C is lower than that of unhardened material, this no doubt reflecting the disappearance, or at least the elevation, of the transition temperature. 

Other important properties for photovoltaic materials are their refractive index, stability, brittleness, toxicity, crystal lattice constant, thermal expansion coefficient, temperatures required for processing into cells, energy investment for cell production, ability to be doped both types, level of technological knowledge and industrial maturity, cost, and abundance. Issues particular to passivation and the trapping of weakly absorbed light include the availability of compatible and affordable passivation and surface texturing methods. ... 

Changes in the thermal properties of SC films were correlated with effects on the mechanical properties of film, i.e., reduced film strength and increased film elongation. Plasticizations disrupt intermolecular interactions between polymer molecules with the effect of decreasing brittleness and increasing film flexibility (Sears and Darby, 1982). Lillie and Gosline (1993) pointed out that the Tg of proteins, especially at a low water content, may occur over a wide temperature range. However, few Tg data are available for proteins (Roos, 1995). 

TSE at 210°C / mechanical and thermal properties / DMA / ductile-brittle transition temperatures / SEM / selective solvent extraction / DSC / MFR / evidence for PP-EPDM copolymer internal mixer at 190°C / mechanical properties vs. use of unfunctionalized PP / PP and dimethylol phenol(2-4%) premixed before addition of rubber / optional addition of additional coupling agent / addition of 0-7.5% amine-terminated NBR... 

Physical and thermal properties UF is a thermoset. It is brittle and stiff, so requires filler or reinforcement. Organic fillers are required for UF because it is more sensitive to the high temperatures required for inorganic fillers than MF. High tensile strength. Low water absorption. 

The glass transition temperature corresponds to the upper temperature limit of heat resistance of plastics. The lower hmit of thermal performance is a brittleness temperature (a temperature at which polymers can be fractured even at small deformations). This lower limit of performance temperature is about 10-170°C below the glass transition temperature. It depends on the type of polymer, its strength properties, and plasticizer type and content. 

Blending results in a reduction of brittleness of phenolics and in an improves thermal properties. The blends show only one glass transition temperature. Heating of the blends results in a molecular weight increase, branching and crosslinking of the phenolic prepolymer and causes a phase separation. 

In this second edition of handbook, discussions regarding low-temperature brittle point, Vicat softening point, oxidative induction time, melt and crystallization parameters using DSC, and thermal degradation using TGA are added in order to bring around completion of comprehension on thermal properties of polymers and blends. 

The major benefit with this approach is that some degree of toughness can be given to inherently brittle cured epoxy matrices designed to operate at service temperatures above about 135 to 150°C, that is, highly cross-linked adhesives. Further, as most of the thermoplastics used also have TgS at these levels or considerably above, should some polymer remain in the continuous phase after cure, the effect on the final thermal properties will not be as deleterious as with RLP or elastomeric toughening. 

Thermal properties n. All properties of materials involving heat or changes in temperature. In Section 08 of ASTM s Annual Book of Standards ( Plastics ), tests listed under Thermal Properties include many properties, from brittleness temperature, coefficient of expansion, deflection temperature, etc., to heat of fusion, glass-transition temperature, thermal conductivity, heat capacity, mold shrinkage, flammability, and many more. 

The physical and thermal properties of bacterial PHA copolymers can be regulated by varying their molecular structure and copolymer compositions. The P(3HB) homopolymer is a relatively stiff and brittle material. The introduction of hy-droxyalkanoate comonomers into a P(3HB) chain greatly improves its mechanical properties. The PHA family of polyesters offers a wide variety of polymeric materials, from hard ciystalline plastic to elastic rubber. The PHA materials behave as thermoplastics with melting temperatures of 50-180°C and can be processed by conventional extrusion and molding equipment (Holm 1988). 

Various thermal material properties (as opposed to thermal stability. Chapter 9) are discussed in Chapter 16. These include coefficient of expansion, melting temperature, Vicat softening point, heat deflection/distortion temperature by thermomechanical analysis, also brittleness temperature, minimum filming temperature, delamination temperature, meltflow index, heat of volatilisation, thermal conductivity, specific heat and ageing in air. 

Microcrystalline quartz is obtained by pulverizing quartz sands and is a hard solid (7 Mohs). It increases the thermal shock resistance in brittle resins - some filled thermosetting resins are cracked by relatively few thermal cycles between, say, ambient temperature and 100°C - when added at high concentrations (typically 100-200 parts per hundred by weight). It can be surface treated with an aminosilane to enhance adhesion, when used in epoxy compositions to improve flexural modulus, electrical insulation or thermal properties, and in the case of unsaturated polyesters, it can be treated with a methacrylic silane. 

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