The invention relates to a method for manufacturing a composite product comprising organic natural fiber material and matrix material, wherein the method comprises mixing the organic natural fiber material with the matrix material in a primary mixing stage to form a mixture. The primary mixing stage comprises a contacting step in which the organic natural fiber material comes in contact with the matrix material that is at least partly in a form of melt, and bulk density of the organic natural fiber material is less than 500 kg/m.sup.3. The method further comprises forming a composite product comprising the mixture. Further, the invention relates to a composite product, a use of the composite product, and a system for manufacturing a composite product.

Puck and collar alignment device embodiments facilitate simultaneous insertion of free end portions of screw shafts into open end portions of complementary drive couplings. The embodiments have alignment keys that correct deviations in alignment and rotation introduced while moving the screw shafts though a barrel of an extruder. Tapered front faces of the alignment keys incrementally adjust coaxial alignment, and tapered side faces of the alignment keys incrementally adjust rotational position cooperatively between the alignment devices and drive couplings. The coaxial and rotational position adjustments cooperate to simultaneously guide multiple alignment keys to fit within corresponding keyway sections while providing alignment of external splines on the screw shafts to interlock in a timed relationship with internal splines on the drive couplings during the simultaneous insertion.

System and method for producing plastic products from a recycled plastic mix of unidentified, unclean and unsorted mixed plastic waste comprises the thermal and mechanical processing of the recycled plastic waste using continuous extrusion foaming, two-phase cooling, continuous metering of the pulling strength and automatic adjustment of the pulling speed and extrusion speed.

A polyamide resin is produced by polycondensing a polyamide oligomer having a relative viscosity of from 1.1 to 1.3 and a water content of 3% by weight or less by melt-kneading using an intermeshed co-rotation twin screw extruder having at least one or more open vents OV1 and OV2 and at least one or more vacuum vents VV1 and VV2. A pressure-decreasing element Y for increasing the resin filling rate is provided at a position nearer to the supply section side than positions at which the vacuum vents VV1 and VV2 are provided, and an area of 30% or less of the total screw length is a vacuum area having a pressure of 300 Torr or less.