Experimental evaluation of anisotropy in injection molded polypropylene/wood fiber biocomposites

• Although the anisotropy of wood fibers is reasonably well established, the anisotropy of injection molded wood fiber composites is not well understood. This work focuses on chemo-thermomechanical pulp (CTMP) reinforced polypropylene (PP) composites. A kinetic mixer (Gelimat) is used for compounding CTMP/PP composites, followed by injection molding. Effects from processing induced orientation on mechanical properties are investigated. For this purpose, a film gate mold was designed to inject composites in the shape of plates so that specimens in different directions to the flow could be evaluated. Observations from tensile tests were complemented by performing flexural tests (in different directions) on discs cut from the injected plates. SEM was used to qualitatively observe the fiber orientation in the composites. At high fiber content, both modulus and tensile strength could differ by as much as 40% along the flow and transverse to the flow. The fiber orientation was strongly increased at the highest fiber content, as concluded from theoretical analysis.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Kompositmaterial och -teknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Composite Science and Engineering (hsv//eng)

Nyckelord

A. Wood

C. Anisotropy

CTMP orientation

E. Injection molding

Melt processing

Anisotropy

Fibers

Molding

Polypropylenes

Reinforced plastics

Tensile strength

Tensile testing

Thermomechanical pulp

Wood

Wood products

Bio-composites

E. Injection moldings

Experimental evaluation

Fiber contents

Flexural tests

Induced orientation

Wood-fiber composites

Injection molding

Polymeric Composite Materials

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