Crystallization nucleating agents

Barium bromide is very soluble in methanol, yet almost insoluble in ethanol. Repotted uses of barium bromide include fabrication of phosphors, for example from Bap2, BaBi2 2H O and EuBy (6) as a crystallization nucleating agent to control supercooling of CaBi2 solutions (7) and in the production... 

Wanamaker, C.L., Tolman, W.B. and Htilmyer, M.A. (2009) 2-Biopolymers poly(D-lactide)-poly(menthide)-poly(D-lactide) triblock copolymers as crystal nucleating agents for poly(L-lactide). Macromolecular Symposia, 283-284,130-138. 

PLA based compositions with a plasticizer and a crystal nucleating agent have been reported (18). Plasticizers are collected in Table 3.2. 

As crystal nucleating agent ethylene bis-12-hydroxystearic acid amide or hexamethylene bis-12-hydroxystearic acid amide can be used (18). Ethylene bis-12-hydroxystearic acid amide is more preferable from the viewpoint of the moldability, heat resistance, impact resistance and anti-blooming property of the biodegradable resin composition (21). 

The crystallization behavior of PLA was also studied in the presence of a crystal nucleating agent, ethylene-bishydroxystearamide (EBH) by Tang et al. 

Foams were produced from poly(lactic acid) using wood fibers as nucleating agent. The cellulosic fibers, acting as crystal nucleating agents, increased the crystallization temperature and the crystallinity and decreased the crystallization half time. ... 

A crystal nucleating agent that is suitable for promoting the crystallization of polyester, particularly phenylphosphorric acid metal salts can be produced in errviromnentally friendly process."... 

Gahleitner, M Wolfschwenger, J Mileva, D, Polymer Crystal Nucleating Agents. Reference Module in Materials Science and Materials Engineering, Elsevier, 2016. 

In the DSC cooling of PP from the melt, crystallization occurs. The minimum of the exothermic peak defines the crystallization temperature. This temperature is an indication of how rapidly the PP crystallizes. The higher the temperature, the more rapid the crystallization. Nucleating agents added to PP increase the crystallization rate of PP, resulting in a higher crystallization temperature. PP crystallizes such that crystalline structures called spherulites are formed. Nucle-ation results in the formation of smaller spherulites than would otherwise have been formed. This, importantly, results in increased clarity and stiffness but also imparts some possibly undesirable features, such as warpage or brittleness. 

PCL was also blended with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymers on a small two-roll mill for 5 min at 140 °C (12% HV) or 128 °C (20% HV). The blends were injection moulded to produce tensile test samples. Samples were prepared in the presence of 1 wt % hydroxyapatite as a crystal nucleating agent and to reduce sample preparation time. For both copolymers, the addition of PCL (10 wt %) reduced the initial modulus and tensile strength (Table 12). Samples containing 90 wt % of PCL exhibited properties very similar to those of PCL and the effects were attributed to phase separation from the blends brought about by PHBV crystallisation at temperatures exceeding T for PCL. That is, the samples show immiscibility. Even blends containing 10 wt % PCL samples aimealed in aqueous media or in an oven showed the presence of crystalline PCL. 

Bo Kong. Study on liquid crystalline polymers as a new -crystal nucleating agent to induce crystallization behavior of PP. Shenyang Northeastern University, 2009. 

These disadvantages are due to the crystalline properties of the crystalline polymer compounds. The solution is to form fine crystals very rapidly. In order to do this, the crystallization temperature may be increased, or crystal nucleating agents and crystallization promoters may be added (6). 

M. Gahleitner and J. Wolfschwenger, "Polymer crystal nucleating agents," in K.H.J. Buschow, R. Cahn, M.C. Flemings, B. Ilschner, E.J. Kramer, S. Mahajan, and P. Veyssiere, eds.. Encyclopedia of Materials Science and Technology, pp. 7239-7244. Elsevier, Oxford, 2001. 

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