Poly Etch Research Articles

Chemical etching of poly(ethylene terephthalate) filaments

AbstractChemical etching of poly(ethylene terephthalate) filaments with aqueous methylamine has revealed a complex stress—cracking behavior, which varied with orientation and thermal crystallization conditions. The appearance of both longitudinal and transverse cracks, can be explained on the basis of the existence of two types of domains, where the stresses are preferentially concentrated. They are explained on the basis of Prevorsek's structural model. In heat‐set fibers, there exists a skin to core differentiation in the internal stress distribution. The crack pattern also varied depending on whether the fibers were heat‐set in the taut or slack conditions. This chemical etching technique can prove to be a very useful tool, for the study of the internal stress distribution induced in fibers by various fabrication processes or post mechanical deformations.

Plasma etching of polysilicon and Si3N4in SF6with some impact on MOS device characteristics

Accurate delineation of the circuit materials polycrystalline silicon (poly), and silicon nitride are important requirements of most SFC process sequences. We have investigated the use of SF 6 as an active species in the parallel-plate plasma etching of these materials. For the etching of poly there is good selectivity (better the 50:1) with respect to the etch rates of SiO 2 and positive photoresist. This process has been used in the fabrication of MOS transistor with 3-µm poly-gate lengths and threshold voltages vary by less than 0.05 V both across a wafer and from wafer to wafer. Etching of nitride is less selective and less isotropic than that of poly.

Surface modification of polyethylene by radiation‐induced grafting for adhesive bonding. IV Improvement in wet peel strength

AbstractAdhesive joints of hydrolyzed methyl acrylate grafts, bonded with epoxy adhesives, yield extremely high peel strength (adherend failure) in dry conditions. However, when the joints are exposed to humid environments, the peel strenght rapidly decreases with exposure time and then reaches a constant value (wet peel strength). Since the locus of failure changes from the adherend to the homopolymer layer with decreasing peel strength, the decrease is due to a decrease in mechanical strength of the homopolymer layer itself, which results from its swelling by water absorption. Many attempts to reduce the swelling of the homopolymer layer or to strengthen the swollen homopolymer layer were unsuccessful except (1) priming with epoxy solutions consisting of a base epoxy resin and organic solvents which can dissolve not only epoxy resins but also hydrolyzed poly(methyl acrylate) and (2) partial etching of the homopolymer layer by photo‐oxidative degradation. All the results on the improvement in wet peel strength can be explained in terms of the penetration of epoxy resins into the homopolymer layer and subsequent curing of the penetrated epoxy resin.

Mechanism of the formation of rough surfaces on poly(ethylene terephthalate) films prepared by chemical etching in aqueous alkaline solutions

A kinetic study was made of the etching of poly(ethylene terephthalate) (PETP) films in aqueous solutions of potassium hydroxide. An equation describing the accumulation of degradation products during the etching process was derived. A mechanism relating to the formation of rough surfaces of PETP films is proposed.

Etching of crystalline poly(ethylene terephthalate) by hydrolysis

AbstractConditions have been found for the etching of poly(ethylene terephthalate) with water so that the crystalline portions alone remain. Initial sample and hydrolysis products are analyzed by extraction of low molecular weight products; density, viscosity molecular weight, and endgroup determination; heating‐rate‐dependent thermal analysis; low‐angle and wide‐angle x‐ray analysis; and electron microscopy. On hydrolysis of a 67% crystalline polymer at 180°C for about 300 min, almost fully crystalline extended‐chain oligomers can be obtained with about 65% yield. The morphology of melt‐crystallized poly(ethylene terephthalate) and the melting behavior of oligomer lamellae are discussed.