Determination of the Avrami exponent of partially crystallized polymers by DSC- (DTA-) analyses

Abstract

This paper presents a new method for a rapid determination of the Avrami exponent n by nonisothermal thermoanalytic analysis (DSC and DTA, resp.). Contrary to conventional techniques this method can be used in the entire temperature range and therefore it is applicable to polymers crystallizing from the melt. The proposed technique is applied to injection moulded low density polyethylene (LDPE), injection moulded high density polyethylene (HDPE), unpigmented extruded polypropylene (PPunpi~m) and pigmented extruded polypropylene (PPpigm)-The resulting values for .5 " the Avraml exponents nLDPE--2.9, nHDrE--1.3, nvp --2 2 and npp ~ 2.1 derived by unlm " lm 9 .. pg]' pg . .crystalhzauon from the melt were compared with ,sothermal measurements and with results given by other authors.

Non‐Isothermal Crystallization of Poly(trimethylene terephthalate) (PTT)/Clay Nanocomposites

“…[15][16][17] The Ozawa's model is a rather simple equation to determine the Avrami exponents from non-isothermal DSC data, and is an extension of the theory proposed by Evans for isothermal crystallization. [18] This model assumes that crystallization occurs at a constant cooling rate Q, and the crystallization originates from a distribution of nuclei that grow as spherulites with a constant radial growth rate at a given temperature.…”

Effect of Organoclays on Nonisothermal Crystallization Kinetics of Poly (trimethylene terephthalate) Nanocomposite

“…From Figure 1 it is evident that the tensile modulus deviate positively from the above two models, which implies that stiffness of poly (trimethylene terepthalate) increases with the increasing the clay content. The tensile modulus is continuously increases with increase in clay content up to 0.32 vol% or 5 wt% [38] . Figure 2 shows the thermograph of PTT and PTT nanocomposites at three different cooling rates.…”

“…This effect becomes more evident when the difference in cooling rate is in a larger range. To reduce the influence of a large range of cooling rate on the linearity of the Ozawa plot, another approach is the Avrami equation to study the nonisothermal crystallization [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] .…”

Study of the Nonisothermal Crystallization Kinetics and Melting Behaviors of Polypropylene Reinforced with Single-Walled Carbon Nanotubes Nanocomposite

“…Conversely, only a few models have been developed to explain nonisothermal regimes; the theoretical models of Avrami, [24] Ozawa, [25] Ziabicki, [26] Jeziorny, [27,28] and Harnisch-Muschik [29] are usually applied. In this study, the results obtained from a modified Avrami analysis are compared with those calculated using the Ozawa and Seo-Kim methods to study the nonisothermal crystallization kinetics of PP reinforced with SWNT.…”