Multi-Scale Evaluation of the Effect of Phenol Formaldehyde Resin Impregnation on the Dimensional Stability and Mechanical Properties of Pinus Massoniana Lamb.

Wang Wang,Li Li,Cai Cai,Xie Xie,Chen Chen,Yuan Yuan

doi:10.3390/f10080646

Abstract

The local chemistry and mechanics of the control and phenol formaldehyde (PF) resin modified wood cell walls were analyzed to illustrate the modification mechanism of wood. Masson pine (Pinus massoniana Lamb.) is most widely distributed in the subtropical regions of China. However, the dimensional instability and low strength of the wood limits its use. Thus, the wood was modified by PF resin at concentrations of 15%, 20%, 25%, and 30%, respectively. The density, surface morphology, chemical structure, cell wall mechanics, shrinking and swelling properties, and macro-mechanical properties of Masson pine wood were analyzed to evaluate the modification effectiveness. The morphology and Raman spectra changes indicated that PF resin not only filled in the cell lumens, but also penetrated into cell walls and interacted with cell wall polymers. The filling and diffusing of resin in wood resulted in improved dimensional stability, such as lower swelling and shrinking coefficients, an increase in the elastic modulus (Er) and hardness (H) of wood cell walls, the hardness of the transverse section and compressive strength of the wood. Both the dimensional stability and mechanical properties improved as the PF concentration increased to 20%; that is, a PF concentration of 20% may be preferred to modify Masson pine wood.

Highlights

Pinus massoniana Lamb., commonly known as Masson pine, is one of the most widely distributed tree species in the subtropical regions of China [1]
phenol formaldehyde (PF) resin was impregnated into the wood cell lumen and diffused into the cell walls, as in verified paper
PF resin was impregnated into the wood cell lumen and diffused into the cell walls, as verified by scanning electron microscopy and Raman spectrum

Summary

Introduction

Pinus massoniana Lamb., commonly known as Masson pine, is one of the most widely distributed tree species in the subtropical regions of China [1]. The wood from Masson pine planted forests has become an important industrial raw material for wide commercial use such as wood construction, wood-based panels, and polymer composites due to the beautiful wood grain, good adaptability to the environment, and shorter growth cycle [2,3]. As one of the common fast-growing tree species, Masson pine wood presents drawbacks which limit its practical application, such as low dimensional stability, softness, and low bio-durability [4,5]. Among the existing chemical modification methods, impregnating and curing the wood with resins appears to especially promote the industrial utilization of wood [11,12]

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