Crystallization of amorphous poly(lactic acid) (PLA) was investigated in various organic solvents, such as acetone, ethylacetate, diethylether, tetrahydrofurane, methanol, hexane, toluene, xylene, and o-dichlorobenene. Most of the solvents, except hexane, induced crystallization of amorphous PLA. Acetone was the most effective solvent to accelerate the crystallization among the solvents used. The crystallization was induced by permeation of acetone into the amorphous phase of PLA, and the permeation obeyed Fick type diffusion. The crystallization rate increased with increasing of conducting temperature. Crystallized PLA formed a crystalline structure. The permeated acetone in the crystallized PLA gradually evaporated as time passes, and the elimination of acetone affected thermal and mechanical properties of the crystallized PLA.

Three kinds of all‐ortho methylene‐linked phenolic oligomers, i.e., 4‐tert‐butylphenol (BP), phenol (AO), and O‐methylated BP (BPM), were prepared with good yields and their dilute solution properties were studied. In acetone, all of these oligomers are highly solvated and molecularly dispersed. In chloroform, however, AO and BP molecules strongly form hydrogen bonds among themselves. By intramolecular and intermolecular hydrogen‐bondings, a large portion of the dimers and the trimers of AO and BP associate to form bimolecular aggregates in chloroform, assuming pseudo‐cyclic conformations analogous to calix [4] arene and calix [6] arene, respectively. By intramolecular hydrogen‐bonding, the tetramers and the hexamers also form pseudo‐cyclic conformations by themselves in chloroform. © 1993 John Wiley & Sons, Inc.