HYBRID POLYMER-MATRIX COMPOSITE AND PROCESSING METHOD

Abstract

A hybrid polymer-matrix composite is described, containing between 10.0% and 45.0% by weight of cellulosic fiber up to 3.0 mm long and with a maximum moisture content of 5.0%; between 5.0% and 40.0% by weight of synthetic fiber up to 4.0 mm long and compatibilizing additives, said constituents being homogenized directly in the twin-screw extruder, with each reinforcing fiber entering via a specific feeder, to be adjusted to the temperature and shearing applied to the reinforcing fibers, guaranteeing the correct dispersion of the fiber for encapsulation by the polymer matrix, optimizing interface interactions and perfect homogenization.

Claims

1. HYBRID POLYMER-MATRIX COMPOSITE characterized by comprising a polymer matrix in which it is associated between 10.0 to 45.0% w/w of cellulosic fiber with up to 3.0 mm in length and maximum humidity of 5.0%; between 5.0 to 40.0% w/w of synthetic fiber up to 4.0 mm in length and compatibilizing additives.

2. HYBRID POLYMER-MATRIX COMPOSITE, according to claim 1, characterized in that the polymer matrix is selected from polyethylene (PE), polypropylene (PP), ethyl vinyl acetate (EVA), polyester (PES) or thermoplastic polyurethane (TPU).

3. HYBRID POLYMER-MATRIX COMPOSITE, according to claim 1, characterized in that the cellulosic fiber is selected from wood, cane, coconut, jute and bamboo fibers.

4. A hybrid polymer-matrix COMPOSITE characterized by the fact that cellulosic fiber and synthetic fiber are mixed with the polymer matrix during the extrusion process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0020] The hybrid polymer-matrix composite, object of the present invention patent, comprises a polymer matrix in which is associated between 10.0 to 45.0% w/w of cellulosic fiber, between 5.0 to 40.0% w/w of synthetic fiber and compatibilizing additives to promote the interface between the reinforcing fibers (synthetic and natural) and the polymer matrix, in order to enhance the performance properties of the product, optimizing the performance of the final product, without losing the recycling property.

[0021] The polymer matrix is selected from polyethylene (PE), polypropylene (PP), ethyl vinyl acetate (EVA), polyester (PES) or thermoplastic polyurethane (TPU).

[0022] The cellulosic fiber has a fiber length of up to 3 mm and a maximum moisture content of 5%, and is preferably selected from wood, cane, coconut, jute and bamboo fibers.

[0023] The synthetic fibers are selected from glass fiber, carbon fiber or aramid fiber, with a length of up to 4 mm, adding considerably greater thermal and mechanical resistance to the product where it will be applied, as this type of fiber is more rigid and structured than the natural fiber.

[0024] The length of the incorporated fibers allows the possibility of dosing in the extruder feeders, without causing agglomeration.

[0025] The method of processing the hybrid polymer-matrix composite comprises the incorporation of the cellulosic fiber and the incorporation of the synthetic fiber in a specific feeder of a double-screw extruder. Thus, unlike state-of-the-art composites in which the reinforcing fillers are mixed with the polymer matrix prior to extrusion, in the method described in the present invention, the reinforcing fibers are added to the feeders in a specific concentration and size, due to the geometry of the transport screw, ensuring proper dispersion of the fiber for encapsulation by the polymer matrix and shear adjustment, in order to optimize interfacial interactions, with the shear adjustment being performed at the time of extrusion and not at the time of fiber dosing.

[0026] Mechanical and thermal tests were carried out with extruded parts using composite A (45.0% w/w of cellulosic fiber), composite B (40.0% w/w of cellulosic fiber and 10.0% w/w of synthetic fiber), composite C (30.0% w/w of cellulosic fiber and 20.0% w/w of synthetic fiber) and composite D (20.0% w/w of cellulosic fiber and 30.0% w/w of synthetic fiber), with the results shown in Table 1.

TABLE-US-00001 TABLE 1 mechanical and thermal tests Test Composite A Composite B Composite C Composite D Density (g/cm.sup.3) 1.06 to 1.10 1.10 to 1.14 1.14 to 1.18 1.18 to 1.22 HDT L (° C.) >110 >125 >135 >140 HDTT (° C.) >90 >105 >115 >120 Vicat (° C.) >115 >125 >130 >135 Modulus of elasticity under bending L (Mpa) >3200 >3500 >4500 >6500 Modulus of elasticity under bending T (Mpa) >2000 >2200 >2800 >3000 Flexural strength L (MPa) >45 >65 >80 >120 Flexural strength T (Mpa) >35 >45 >55 >60 Tensile strength L (MPa) >20 >30 >40 >60 Tensile strength L (Mpa) >15 >20 >30 >35

[0027] Molding tests were carried out with the extruded plates using composite C, in traditional molding equipment, having a good moldability, presenting a conformation result, format copying and dimensional stability quite satisfactory.