A method for preparing a pre-bond surface of a composite structure includes the steps of: (1) separating a peel ply, co-cured with a composite substrate, from the composite substrate; and (2) transferring an identifiable marking agent from the peel ply to the composite substrate upon separation of the peel ply from the composite substrate. Residue of the peel ply, transferred from the peel ply to the composite substrate upon separation of the peel ply from the composite substrate, is layered on the identifiable marking agent.

A maleimide-based copolymer which allows to obtain a resin composition having balanced heat resistance providing property and impact resistance, superior flowabillty, and low yellowness (YI); a maleimide-based copolymer composition using such maleimide-based copolymer; a resin composition.; and an injection molded body are provided. A maleimide-based copolymer, including: aromatic vinyl monomer unit, vinyl cyanide monomer unit, and maleimide monomer unit; wherein: the maleimide-based copolymer has a weight average molecular weight of 50,000 to 110,000; and the maleimide-based copolymer has a mid-point glass transition temperature measured in accordance with JIS K-7121 of 165° C. to 200° C., is provided.

An assembly of two parts, one of the parts being made of composite material with fiber reinforcement obtained from a fiber preform made by three-dimensional weaving and densified with a matrix, the assembly including a mechanical anchor element secured to one of the parts and inserted inside the other part.

An assembly of two parts, one of the parts being made of composite material with fiber reinforcement obtained from a fiber preform made by three-dimensional weaving and densified with a matrix, the assembly including a mechanical anchor element secured to one of the parts and inserted inside the other part.

A method for repairing a sandwich composite structure comprising a pinned foam core. In the sub-region in which the pinned foam core is damaged, the at least one upper or lower cover layer is removed as far as the pinned foam. The pinned foam core is removed. A pinned replacement foam core is inserted, the pinned replacement foam core being impregnated with a resin. An upper or lower replacement cover layer is applied. The pinned replacement foam core and optionally the upper or lower replacement cover layer are cured.

Low-density thermoplastic expandable microspheres are disclosed. Various low-density structures, in particular, sandwich panels, based on foam prepared from the low-density microspheres, are also disclosed. Process of preparing low-density polymeric microspheres, per se, and the corresponding low-density structures, based on the microsphere foam, are also disclosed.

A polyamide acid of the present invention contains, as a diamine component, 2,2-bistrifluoromethylbenzidine and trans-1,4-cyclohexanediamine, and contains, as a tetracarboxylic acid dianhydride component, a pyromellitic acid anhydride and a 3,3,4,4-biphenyltetracarboxylic acid dianhydride. A ratio of the trans-1,4-cyclohexanediamine to a total amount of the diamine is preferably 0.5-40 mol %. A polyimide is obtained by dehydration ring closure of the polyamide acid.

The present invention provides methods, processes, and systems for the manufacture of three-dimensional articles made of polymers using 3D printing. A layer of prepolymer is deposited on a build plate to form a powder bed. The deposited powder bed is heated to about 50° C. to about 170° C. Then, a solution of activating agent is printed on the powder bed in a predetermined pattern, and a stimulus is applied converting the prepolymer to the final polymer. After a predetermined period of time, sequential layers are printed to provide the three-dimensional article. The three-dimensional object can be cured to produce the three-dimensional article composed of the final polymers.

The present invention relates to a method of controlling a step of a process carried out by a machine. The invention is characterized in that a sensor is used to measure a variable characteristic with an exponential course for a step, and with the aid of several consecutive measurements of the characteristic variable a time constant of the exponential change is determined, and the step is ended after it has been carried out for a period of time corresponding to a predetermined multiple of the time constant.

Material mixing for an additive manufacturing apparatus is provided. A further aspect employs multiple material inlets for simultaneously feeding a polymer and/or nanocomposite material in at least a first inlet, and ceramic or other particles in at least a second inlet, to a single additive manufacturing outlet nozzle. In another aspect, a three dimensional printing machine varies a chemical or compounding characteristic, such as a loading percentage, of printing material during printing. In another aspect, in situ mixing of a polymer and/or nanocomposite with variable amounts of ceramic, magnetic or other particles therein in an additive manufacturing apparatus, such as a multi-material aerosol jet printing machine.