Influence of interfacial interactions on the properties of PVC/cellulosic fiber composites

Abstract

The surface properties at the interface between thermoplastic and cellulosic fibers strongly influence the mechanical properties of plastic/cellulosic fiber composites. This paper examines the role of surface acid‐base properties of plasticized PVC and cellulosic fibers on the mechanical properties of the composites. The acid‐base surface characteristics of cellulosic fibers were modified by treating the fibers with γ‐aminopropyltriethoxysilane (A‐1100), dichlorodiethylsilane, phthalic anhydride, and maleated polypropylene. The empirical acid (KA) and base (KD) characteristics (i.e., electron donor/acceptor abilities) of untreated and treated fibers, as well as plasticized PVC, were determined using inverse gas chromatography (IGC) technique. These parameters were used to yield information on the acid‐base pair interactions that were correlated with the tensile and notched Izod impact properties of the composites. Acid‐base pair interactions have been found to be a valuable parameter in the design of surface modification strategies intended to optimize the tensile strength of the composites. By tailoring the acid‐base characteristics of cellulosic fibers and plasticized PVC, a composite with equal tensile strength and greater modulus than unfilled PVC was developed. However, the acid‐base factors did not correlate with tensile modulus, the elongation at break, and the notched Izod impact property of PVC/newsprint fiber composites. Aminosilane has been observed to be a suitable adhesion promoter for PVC/wood composites improving significantly the tensile strength of the composites. Other treatments (dichlorodiethylsilane, phtalic anhydride, and maleated polypropylene) were found to be ineffective, giving similar strength compared to the composites with untreated cellulosic fibers. FTIR spectroscopy results suggested that aminosilane was effective because treated cellulosic fibers can react with PVC to form chemical bonds. The resulting bond between PVC and cellulosic fibers accounts for the effectiveness of aminosilane, when compared with other coupling agents.

Effects of Silane Surface Treatment of Cellulose Nanocrystals on the Tensile Properties of Cellulose-Polyvinyl chloride Nanocomposite

“…The organofunctional group is responsible for bonding with the polymer via covalent reaction or physical interaction with other phases. Matuana et al (1998a;1998b) found that the adhesion between PVC and cellulosic fibers was significantly improved with aminosilane. Figure 1 shows a schematic illustration of the possible interface between silane modified cellulose nanocrystals (SCNC) and poly (vinyl chloride) matrix (PVC).…”

Effect of gas saturation conditions on the expansion ratio of microcellular poly(lactic acid)/wood-flour composites

“…Previous efforts to overcome the cost of PLA included blending with fillers such as cellulosic fibers [5]. However, the lowered cost due to filler addition is usually achieved at the expense of other properties such as the ductility (lower elongation at break) and lower impact resistance, because the incorporated brittle cellulosic fibers alter the ductile mode of failure of the matrix, making the composites more brittle than neat polymer [6][7][8]. Continuous efforts seek to further reduce the cost of PLA while enhancing its flexibility and toughness.…”

Compósitos de PVC rígido e fibras de bananeira: Efeito do tratamento da fibra

“…Também não foi observado uma alteração significativa do módulo de Young com adição da fibra de bananeira não tratada e tratada. Este comportamento pode estar relacionado com o fato do PVC utilizado ser rígido, pois os autores que observaram um aumento significativo do módulo de Young em compósitos de PVC com fibras naturais utilizaram matrizes plastificadas e os valores máximos alcançados nos compósitos obtidos são próximos aos observados neste trabalho [8][9][10][11] com PVC rígido. …”

“…Hoje já são utilizadas fibras de sisal, bambu, bagaço de cana-de-açúcar, curauá, madeira, fibra de bananeira, entre outras. O emprego de fibras naturais como reforço em matriz polimérica, tanto utilizando materiais termofixos como as resinas de poliésteres, epóxis e fenólicas como termoplásticos, principalmente o polipropileno (PP), polietileno (PE) [6,7] e poucos estudos utilizam o poli (cloreto de vinila) (PVC) flexível [8][9][10][11][12][13][14] e rígido [15,16]. Zainudin et al [15] avaliaram a degradação térmica de compósitos de PVC rígido e fibra de bananeira, e foi observado que a adição das fibras não altera o processo de degradação térmica do PVC.…”