The lattice disordering transition (LDT) and the domain dissolution transition (DDT) of a highly asymmetric polystyrene-block-poly(ethylene-co-but-1-ene)-block-polystyrene (SEBS-8) triblock copolymer with a volume fraction of polystyrene (PS) block of 0.084 have been investigated by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and rheology. The PS spheres formed in the SEBS-8 sample exhibited a body-centered cubic (bcc) lattice at lower temperatures and underwent disordering in the bcc lattice (so-called LDT) at ∼150 °C. Above this temperature (T LDT), spheres in liquidlike short-range order (LSO) with relatively thin interface between the PS domain and the poly(ethylene-co-but-1-ene) (PEB) matrix were detected up to ∼210 °C, above which the spherical domains started to dissolve into the PEB matrix. Finally, the spherical domains were completely dissolved into a homogeneous state at ∼232 °C. The starting and the final dissolution temperatures are referred to as the T DDT and the order-to-disorder transition temperature (T ODT). The LDT was verified by the SAXS results that the higher order diffraction peaks from the bcc lattice disappeared above the T LDT, while particle scattering of spheres due to the intraparticle interference as well as the interparticle interference of spheres in LSO was clearly observed between the T LDT and the T DDT. The spheres in LSO were further elucidated by rheology and TEM observation. It was found that a precipitous decrease in storage modulus (G‘) and a dramatic change in the Bragg spacing occurred at the same temperature of the T LDT. It was also observed that the slope in the plots of G‘ versus frequency (ω) and that in the plots of loss modulus (G‘ ‘) versus ω in the terminal region were two and one, respectively, at temperatures above the T LDT. This is attributed to the fact that because of the absence of the bcc lattice in long-range order, spheres in LSO do not contribute significantly to the shear moduli in the terminal region. Therefore, even if the terminal behavior observed generally for a homogeneous mixture (namely the slopes in the plots of G‘ versus ω and G‘ ‘ versus ω are two and one) is exhibited at a temperature, this temperature is not necessarily above the T ODT. The characteristic domain spacing in LSO did not change much with temperature, but it increased between the T DDT and the T ODT due to the dissolution of spheres.

The crystal structure of nylon 3 was studied, and four crystalline modifications were observed. Modification I, as determined from the x‐ray diffraction pattern of drawn fibers, is similar to the α crystal structure of nylon 6. The unit cell is monoclinic; a = 9.33 Å, b = 4.78 Å, (fiber identity period), c = 8.73 Å, and β = 60°. The theoretical density for nylon 3 with four monomeric units in the unit cell is 1.39 g/cm3, and the observed density is 1.33 g/cm3. The space group is P21. The nylon 3 chains are in the extended planar zigzag conformation. Although other odd‐numbered nylon form triclinic or pseudohexagonal crystals when oriented, drawn nylon 3 crystals are monoclinic. In addition to modification I, modifications II, III, and IV were studied. Lattice spacings of modifications II and III are equal to those of modification I. However x‐ray diffraction intensities are different. Infrared spectra of those forms indicate an extended planar zigzag conformation of the chains. Modification IV is thought to correspond to the so‐called smectic hexagonal form. No γ crystals were found, and it appears that polyamide chains with short sequences of methylene groups cannot form crystals of this type.

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For use as electrical and electronics parts, or automobile and mechanical parts, toughened poly(pheny1ene sulfide) (PPS) is desired. For these applications, our investigation centered on improving the toughness of PPS and developing elastomer-toughened PPS and elastomer-toughened compounds of PPS. Using chemically treated PPS and an olefinic elastomer with a functional group, we developed elastomer-toughened PPS using a reactive processing method. In the PPS matrix, the elastomer is finely dispersed. While the notched Izod impact strength of the original PPS is about 1 kgcm/cm, elastomer-toughened PPS has a notched impact strength around 50 kgcm/cm. The notched fracture surface of elastomer-toughened PPS is observed using a scanning electron microscope. We concluded that the mechanism for the toughening is attributed to energy dissipation by matrix yield.

A high formaldehyde feed concentration and a low reaction temperature are among the advantages of using heteropolyacids (phosphotungstic acid and silicotungstic acid) as catalysts in the formation of trioxane; this cyclic trimer of formaldehyde (see scheme) is used in the industrial production of acetal resins. Compared to reactions with a conventional catalyst, like sulfuric acid, trioxane can be produced in higher yield and with higher selectivity.