Glass Transition Temperature and Melting Point

The mechanical properties of PP at a particular temperature are dependent on the glass transition temperature. At very low temperature, the macromolecules are largely immobile. As the polymer is heated, the restricted macromolecular zones become progressively more mobile. At the transition temperatures, the material changes from a glassy hard state to a soft tough state because certain molecular segments become more 

Volume resistivity (D cm) 1E15 1E15 1E15 1E15 1E15 1E15 1E15 

Surface resistivity (0) 1E14 1E14 1E14 1E14 1E14 1E14 1E14 

PP copolymers, due to lower crystallinity, and metallocene-catalysed PP have lower melting points in comparison to homopol5mierised PP. 

Recrystallisation temperature is quite important for injection moulding. Since the recrystallisation temperature of PP is between 115-135 °C, most of the crystallisation occurs during the cooling of the artefact in the mould. Since the recommended mould 

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Figure 4 JO. Relationship between glass transition temperature and melting point. (Reproduced by permission of North-Holland Publishing Company" )...

Copolymers with acrylates (vinyl acrylics) or other vinyl esters are also commonly produced, mostly as aqueous dispersions. They are, independent of the nature of the comonomer, often referred to as copolymers or terpolymers . The presence of comonomers of course heavily influences a number of physical properties like the glass transition temperature and melting point, water solubility or flexibility, to name just a few. 

RELATIONSHIP BETWEEN GLASS TRANSITION TEMPERATURE AND MELTING POINT OF POLYMERS... 

Table 3.61. Glass Transition Temperatures and Melting Points of Fluoroplastics ...

DSC finds many applications in characterizing materials. Quantitative applications include the determination of heals of fusion and the extent of crystallization for crystalline materials. Glass transition temperatures and melting points arc useful for qualitative classification of materials, although thermal methods cannot be used alone for identification. Melting points are also very useful in establishing the purity of various preparations. Hence, Ihcrmal methods are often used in quality control applications. 

Table 1 lists the most interesting matrices and their glass transition temperatures and melting points, which mark the upper limit of applicability as structural composites. 

Table 1 - Glass transition temperatures and melting points of thermoplastics...

Table 16.3 Dependence of Glass Transition Temperature and Melting Point on Composition...

The changes of glass transition temperature and melting point with composition of co(polyester)s prepared from 3-benzoyl-4-acetoxybenzoic acid and 4-acetoxybenzoic acid are shown in Table 16.3. 

The detected temperature values for the first-order (endothermic peak) and the second-order transitions (heat capacity jump) (Table 13.3) were close to the values of the glass transition temperature and melting points of the pure homopolymers. The slightly smaller values of the PA and polyether melting points probably reflect the low molecular weight of the blocks and the less ordered crystallite structure. They can be therefore attributed... 

T T T Temperature, glass transition temperature, and melting point... 

At the early stage of formulation development, formulation scientists can utilize some empirical rules to assess the suitability of an ASD for the API of interest. Simple estimations can be made using the ratio between glass transition temperature and melting point in kelvin as well as the Kauzmann temperature (Tk Fig. 16.1). These estimations often provide quiek educated guesses on the crystallization tendency of the API. Such information will be useful for estimating the difficulty of forming a stable ASD. 

A similar fiber is poly(ethylene naphthalate) or poly(ethylene-2,6-naphthalene dicarboxylate).The use of this fiber may increase considerably in tire cord applications, since its glass transition temperature and melting point are higher than those of PET (Tg = 120°C, = 337°C, A//f = 103 J/g). 

Table III shows some observations of the effect of polymerization temperature on the glass transition temperature and melting point of poly(vinyl chloride).

Chapter 2. Obviously the melting point of a polymer also determines the acceptable temperature range over which it can be used and for thermoplastic materials will limit the maximum service temperature of, for instance, coated wires. Thermoplastic and thermosetting materials are also covered in more detail in Chapter 2. The glass transition temperatures and melting points of several thermoplastic materials are given in Table 1.6. 

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