Effect of fiber and polymer variability on the rheological properties of wood polymer composites during processing

Abstract

We investigated the effects of fiber variability, size and content on the fusion characteristics of wood particlereinforced high-density polyethylene (HDPE). Five types of wood sawdust were used: eastern white cedar, with sapwood, and heartwood treated separately; jack pine divided into wood and bark; and black spruce. Three different fiber length classes were also used. Composite pellets containing wood particles at 25, 35, and 45% by weight with HDPE were made using a corotating twin-screw extruder. The pellets were melted and mixed during 7 min in a torque rheometer at 1808C. We also investigated the polymer variation using HDPE, polypropylen (PP), polyvinyl chloride (PVC), and a blend of (80% HDPE1 20% PP) where wood fiber proportion and length were kept constant. We varied the mixing temperature to reach the melting temperature range of each polymer. Mixing and melting times, maximum torque and stabilized torque were obtained. Adding wood fibers to the HDPE increased processing time and torque energy. At constant fiber length and proportion, torque properties varied with fiber origin. Higher fiber length and proportion increased torque energy and time of stabilization. Thus, using wood fibers with different properties will lead to significant variations in processing, such as in extrusion or injection. The fusion characteristics of wood polymer composite vary among polymers. The PVC showed the highest steady-state torque. The formulation containing a polymer blend of HDPE and PP showed the highest torque energy. This higher torque energy is explained by the interaction of the incompatible polymeric chains of the two thermoplastic polymers. POLYM. COMPOS., 00:000-000, 2018.

Influence of the Processing Conditions on the Mechanical Performance of Sustainable Bio-Based PLA Compounds

“…Consequently, during the mixing, a greater number of collisions between aggregates/agglomerates could be determined, leading to fiber deterioration [ 21 ] or even re-agglomeration phenomena [ 22 ]. It can be concluded that, at lower processing temperatures, the introduction of a greater amount of fibers determines a higher instability, physically linked to the efficiency in their incorporation into the polymer matrix [ 23 ]. However, if the mixing operations were conducted at higher temperatures, the added cellulose seemed to stabilize the effect of time on the workability of the matrix, resulting in a less significant torque decline compared to that of the matrix.…”

Optimization of processing conditions and mechanical properties of banana fiber‐reinforced polylactic acid/high‐density polyethylene biocomposites

“…19 This is the main explanation for the dependence of stabilization torque on the load of the fiber in the BM, as observed in similar mixer studies. 3,20 As for the polymer content, the stabilization torque turned out to be lower when the mixture of polymers in the formulation was richer in PLA.…”

“…2 High-density polyethylene (HDPE), which has a low melting temperature (135 C), is the most widely used polymer in the wood-plastic composite industry. 3 Biopolymers are an alternative or complement to synthetic polymers and are considered green polymers due to their renewable base and biodegradability. 4 Polylactic acid (PLA) and thermoplastic starch are biodegradable polymers widely used as components of BMs.…”

“…Polyethylene and polypropylene are widely used thermoplastic matrices due to their ease of processing, nearly zero moisture absorption, excellent chemical inertness and recyclability 2 . High‐density polyethylene (HDPE), which has a low melting temperature (135°C), is the most widely used polymer in the wood‐plastic composite industry 3 . Biopolymers are an alternative or complement to synthetic polymers and are considered green polymers due to their renewable base and biodegradability 4 .…”

Deconstruction and Reassembly of Renewable Polymers and Biocolloids into Next Generation Structured Materials

“…Research on the subject is quite mature, dating back to at least 80 years ago, with several products reaching the market over the past decades. Currently, research on the subject focuses mostly on technical aspects, such as optimization of processing parameters and formulation, 768,769 public perception and market acceptance, 770…”