Plasticizer thermal expansion coefficient

As a consequence, the overall penetrant uptake cannot be used to get direct informations on the degree of plasticization, due to the multiplicity of the polymer-diluent interactions. The same amount of sorbed water may differently depress the glass transition temperature of systems having different thermal expansion coefficients, hydrogen bond capacity or characterized by a nodular structure that can be easily crazed in presence of sorbed water. The sorption modes, the models used to describe them and the mechanisms of plasticization are presented in the following discussion. 

The low water absorptivity and good resistance to hydrostatic pressure make syntactic foams very useful for marine and submarine construction. Materials to be used for deep-sea application must have 1) low compressibilities at high hydrostatic pressure, 2) low thermal expansion coefficients, 3) low water absorption, and 4) good fire resistance. The fluids used for buoyancy in deep water submersibles include gasoline, ammonia, and silicone oil, while the solids include plastic, glass and aluminium foams, lithium, wood, and monolithic polyolefins. The liquids are dense but have low... 

It is now well established that TCP acts as an antiplasticizer of PVC at low concentrations and as a plasticizer at high concentrations. The observed variations in tensile modulus, tensile strength, impact strength, ultimate elongation, and thermal expansion coefficient of PVC with additive concentration have been attributed to the antiplasticization-plasticization phenomenon (T7, 18, 19). Antiplasticization of PVC also results in a decrease in gas permeability, and plasticization in an increase in gas permeability (17). 

LGMs of the AT/alumina and AT/ZTA displayed some very interesting properties which include excellent machinability, low thermal expansion coefficient, improved thermal shock resistance, low hardness (about 5 GPa), low Young s modulus (E) (250 GPa) and excellent flaw tolerance [Pratapa, 1997 Pratapa Low, 1998 Skala, 2000 Manurung, 2001], These materials appeared to display a large degree of near-surface quasi-plasticity under the Hertzian or the Vickers indenter which effectively inhibits the formation and propagation of cracks. The ductile behaviour of these materials was... 

The physical and chemical properties of both the solidified adhesive and the plastic substrate affect the quality of the bonded joint. Major elements of concern are the thermal expansion coefficient, modulus, and glass transition temperature of the substrate relative to the adhesive. Special consideration is also required of polymeric surfaces that can change during normal aging or on exposure to operating environments. 

Significant differences in the thermal expansion coefficient between the substrate and the adhesive can cause severe stress at the interface. This is common when plastics are bonded to metals because of the difference in thermal expansion coefficients between the substrates. Residual stresses are compounded by thermal cycling and low-temperature service. Selection of a resihent adhesive or adjustments in the adhesive s thermal expansion coefficient via fillers or additives can reduce such stress. 

Cordierite. This material possesses a rare combination of properties, i.e., relatively high strength and hardness, low thermal expansion coefficient, high heat conductivity and plasticity it conserves mechanical strength under thermal shocks. Therefore, its application areas are varied. 

Table 5.20 contains data on the linear thermal expansion coefficient of various fillers. The data indicate that most fillers, especially these used for reinforcement, have much lower coefficient of thermal expansion than metals and plastics. This is an important fact which should be considered in formulating plastics exposed to... 

Thermal expansion Temperature-dependent volume, respectively, longitudinal expansion of a body. Measure is the thermal expansion coefficient a in the dimension 1CT6 K 1 Values a steels 10-20, aluminum and Al-alloys 20-25, glasses 5-10, plastics/adhesive layers 50-100. 

Low temperatures can also affect materials by thermal contraction. The thermal expansion coefficient is a function of temperature. For many materials, which are cooled down from room to cryogenic temperature, more than 90 % of the total contraction experienced will have already taken place at 77 K. Rule-of-thumb figures of thermal contraction are 0.3 % in iron-based alloys, 0.4 % in aluminum, or over 1 % in many plastics [43]. Cryogenic vessels or piping systems must account for this contraction to avoid large thermal stresses. 

As indicated, the thermal expansion coefficient, permeability, elastic modulus, and heat capacity of plastics may have very different values, depending on whether the polymer sample Is above or below its Tg. 

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... 

---