The invention relates to heat treatment of polymorphic semicrystalline or crystallizable polymers to increase the content of the highest melting crystalline form. Such heat treatment results in a polymer powder that has a consistent, uniform melting range, improved flow and improved durability of the powder particle size for applications that require powder flow at elevated temperatures. In addition to improved powder properties, the articles produced from the powders also exhibit better physical properties in both appearance and in mechanical properties. Thus the invention also includes polymer powders and articles produced by the described processes.

Articles comprising a skin layer comprising virgin polymer and a core layer comprising a recycled polymer, along with associated systems and methods, are generally provided.

A method for manufacturing a liner, in particular for the cabinet of a refrigerator, allowing to leave out a deep thermoforming step. The method includes extruding a sheet, trimming the sheet, folding the sheet and joining adjacent edges of the sheet.

A method includes injection molding a preform using a two phase injection system having a first phase in which a material is injected into the preform and a second phase in which the material is injected into the preform. The preform is disposed in a mold. The preform is blow molded into an intermediate article. The intermediate article is trimmed to form a finished container. The first phase includes injecting a material into the preform to form a single layer of the preform and the second phase includes injecting the material to form inner and outer layers and an intermediate layer between the inner and outer layers. The inner and outer layers include the material and the intermediate layer includes at least one additive. Finished containers are disclosed.

A method of blow molding a glossy article having at least one layer of thermoplastic material. The method comprises the steps of feeding a parison of said thermoplastic material into a mold having an inner surface with at least a portion of SPI finish standard selected from the group consisting of A-1, A-2, A-3, B-1, B-2 and B-3 mold and a first temperature of greater than 55 C.; blowing the parison against the inner surface of the mold to form the article; and subsequently lowering the temperature of the mold to a second temperature of between 10 C. to 55 C. before release of the molded article. The cycle time of the mold (t.sub.ct) is less than 250 seconds.

Upon manufacturing a heat-resistant container using PET sheet, high heat-resistance is achieved without a stretching operation. The method comprises a molding sheet-making process, wherein a sheet is made including organic acid metal salt particulates produced by allowing an inorganic basic material or carbonate that is solid at ordinary temperature to react with an organic acid that is solid at ordinary temperature in the equivalent relationship, and a container-molding process, wherein, the molding sheet made in the molding sheet-making process is heated to 80-130 C., formed into a container shape by a vacuum or vacuum-pressure forming machine using a mold, and heat-set by keeping at 130-220 C. in the same mold, and the container formed in the container-molding process has a crystallinity of 18% or more.

The present invention provides an ethylene polymer having a viscosity average molecular weight of 10010.sup.4 or more and 1,00010.sup.4 or less, in which a ratio between an isothermal crystallization time at 125 C. and an isothermal crystallization time at 123 C. obtained under specific isothermal crystallization time measurement conditions is 3.5 or more and 10.0 or less, and a degree of crystallization obtained using a differential scanning calorimeter (DSC) is 40% or more and 75% or less.

The invention relates to a composition for a thermoplastic material comprising: 0 to 70% by weight, preferably 20 to 60% by weight, of short reinforcing fibers, 30 to 100% by weight, preferably 40 to 80% by weight, of a thermoplastic matrix based on at least one semi-crystalline polyamide polymer, 0 to 50% of additives and/or other polymers,
where said semi-crystalline polyamide polymer is: a) a reactive composition comprising or consisting of at least one reactive polyamide prepolymer precursor of said semi-crystalline polyamide polymer, or in alternative to a), b) a non-reactive composition of at least one polyamide polymer where said composition is that of said thermoplastic matrix defined above,
and said reactive polyamide prepolymer for the composition a) and said polyamide polymer for the composition b) comprising or consisting of at least one BACT/XT copolyamide.

A method of 3D printing a part with an extrusion-based additive manufacturing system includes providing a filament having a semi-crystalline material as a majority component of a polymeric matrix to a liquefier having a liquefier tube having an overall length between an inlet end and an outlet end. An upper portion of the liquefier tube adjacent the inlet end has a first length and a first cross-sectional area substantially perpendicular to a longitudinal axis and a lower portion of the liquefier tube adjacent the outlet end has a second length and a second cross-sectional area substantially perpendicular to the longitudinal axis, wherein the first cross-sectional area is greater than the second cross-sectional area. The method includes driving the filament into a melt zone located within the upper portion of the liquefier tube at a selected rate based upon a desired extrusion rate. The filament is melted within the melt zone forming a melt pool in the liquefier tube to provide the selected extrusion rate. The part is printed in a series of layers by extruding the melted filament having a majority of semi-crystalline material along tool paths representative of the part.

Polymer foam and a method for preparing the same are disclosed. In the present disclosure, the method sequentially comprises the following steps: providing a polymer body; performing a pressure-induced flow (PIF) process on the polymer body at a first predetermined temperature and a first predetermined pressure for a pressure holding time, to obtain a polymer sheet; and performing a foaming process on the polymer sheet by using a foaming agent at a second predetermined temperature and a second predetermined pressure for a saturation time, to obtain polymer foam.