Nucleation Efficiencies of Calcium Hexahydrophthalic Acid for Poly(ε-caprolactone) Crystallization

Abstract

Poly­(ε-caprolactone) (PCL) has received widespread attention due to its biocompatibility and biodegradability. Introduction of the nucleating agent (NA) is an effective method to control the crystallization behavior of semicrystalline polymer and regulate their properties. Unfortunately, only a few NAs for PCL have been reported up to now. In this work, considering the structure similarity between PCL and polyethylene (PE), we tried to synthesize the calcium hexahydrophthalic acid (Ca-HHPA), the main ingredient of a special NA for PE, by neutralization reaction in deionized water and investigated its possible nucleating effect for PCL. It was interesting to find that the as-synthesized product undergoing different thermal treatments exhibited obviously different nucleation effects. The Ca-HHPA80, obtained by drying at 80 °C for 24 h, only slightly increased the crystallization peak temperature (T c) of PCL by no more than 1.7 °C with the loadings investigated, while Ca-HHPA80-200, obtained by further annealing Ca-HHPA80 at 200 °C for 5 min, could notably increase the T c by 5.2 °C in similar dosages. The results of structural characterization indicated that the Ca-HHPA80 and Ca-HHPA80-200 were crystalline monohydrated and dehydrated carboxylate, respectively. The investigation of structural evolution behavior during the heating process revealed that the monohydrated carboxylate lost its crystal water and gradually transformed to dehydrated one at 140–190 °C accompanied with the conformational transformation of the methylene from gauche to trans conformation, which led to a great variation of their alkyl chain packing in crystal lattice. Based on the epitaxial crystallization theory, the possible reasons for the obviously improved nucleating efficiency of Ca-HHPA80-200 were discussed. The alkyl chain packing of Ca-HHPA80-200 leading to the lower mismatching with the PCL crystals may be accountable for its relatively higher nucleation efficiency.

Nonionic Emulsifier with Lipophilic–Hydrophilic–Lipophilic Structure for Preparing Waterborne Epoxy Coatings with High Corrosion Resistance and Thermal Stability

“…23 In HHPA, the characteristic bands at 1853 and 1773 cm −1 represent the antisymmetric and symmetric C�O stretching vibrations of anhydride, respectively (Figure 2a). 24 The characteristic band at 913 cm −1 in E51 is attributed to the vibration of the epoxy group (Figure 2a). 25 After the reaction between PEG2000 and HHPA, the Esterification product can be obtained, which then reacts with E51 to produce the WEP emulsifier (E-PEG2000) (Figure 1).…”

“…The 2875 cm –1 band represents the C–H stretching vibration in PEG2000 (Figure a) . In HHPA, the characteristic bands at 1853 and 1773 cm –1 represent the antisymmetric and symmetric CO stretching vibrations of anhydride, respectively (Figure a) . The characteristic band at 913 cm –1 in E51 is attributed to the vibration of the epoxy group (Figure a) .…”

Methyl Addition and Side-Chain Engineering on XT386 Lead to the Discovery of a 2,4,6-Triaminotoluene-Derived Nucleating Agent for Polypropylene

“…Moreover, the crystal growth process of iPP-1a-1 and iPP- x -1 samples lasted 41s and 34s, respectively, which was even one magnitude lower than that of neat iPP (100s). This indicates that the NA 1a can make iPP form more nucleation sites and grow faster and completely . Additionally, the reduction of spherulite size will help to reduce the haze of iPP, which can be used as a clarifier.…”

“…This indicates that the NA 1a can make iPP form more nucleation sites and grow faster and completely. 35 Additionally, the reduction of spherulite size will help to reduce the haze of iPP, which can be used as a clarifier. Furthermore, at a concentration of 1 wt %, it was observed that both compound 2 and NX8000 had a limited impact on increasing the number of nucleation sites in iPP and reducing the spherulite size (Figure 4b,c).…”

Effect of calcium pimelate on crystallization kinetics of polyphenylene sulfide

“…8 Owing to the convenience and costeffectiveness, the use of high efficient NAs has been developed into a common technique used in the industrial practice. Up to now, Numerous nucleating agents have been successfully developed for various important semi-crystalline polymers, such as polypropylene (PP), [9][10][11] polyethylene (PE), 12,13 polyamide (PA), [14][15][16] poly(ethylene terephthalate) (PET), 17 poly(L-lactide) (PLLA), 18,19 Poly(ε-caprolactone) (PCL), 20 make these polymers more extensively applicable. Efforts have also been dedicated to developing suitable NAs for PPS in recent years.…”