Manufacture of wood fiber reinforced polyvinyl acetate rigid foams

Abstract

In this work, rigid foams designed and manufactured using the freeze drying technique were made from polyvinyl acetate (PVAc), bleached kraft pulp and unbleached kraft pulp. The rigid foams designed as an environmentally-friendly product with no pentane or hydrochlorofluorocarbon included in the manufacturing process. The PVAc based foams were reinforced with different kraft pulp contents. Their performance properties such as compressive and flexural strength, physical and morphological properties were investigated according to relevant standards. The foam densities ranged from 0,017 g/cm 3 with %17,65 coefficient of variation (CV) to 0,137 g/cm 3 with %2,33 CV. The compression resistance was found between 0,001 N/mm 2 with %50,00 CV and 0,03 N/mm 2 with %5,98 CV. The flexural resistance was found between 0,005 N/mm 2 with %20,00 CV and 0,11 N/mm 2 with %6,06 CV. Optimum properties were observed at B-4 (PVAc/ Bleached Kraft pulp 1/0.8). Bleached kraft pulp reinforcement gave better results on performance characteristics of foam materials compared to unbleached kraft pulp reinforcement. Overall test results showed that the PVAc based rigid foams have promising results.

Mechanical and thermal properties of polyvinyl acetate foams reinforced with biopolymers

“…Hydrogen peroxide was utilized as a bleaching agent to whiten the pulp and more detailed information was given in our previous study. 14 Zinc borate (Zn 3 BO 6: 85.27% pure) was purchased from Kimetsan Chemistry (Ankara). The density of zinc borate was 2600 kg/m 3 .…”

“…In our previous study, foams produced without water-soluble chitosan and zinc borate determined poor mechanical properties. 14 These poor mechanical properties are thought that there may be several different reasons. First reason, chitosan could react with zinc borate and kraft pulp to form a cross-linked network, which enhanced the mechanical properties.…”

“…13 Commonly bleaching methods are oxygen delignification, ozone bleaching, and peroxide bleaching. 14 Chitosan is a natural polysaccharide obtained from the shells of shellfish, primarily crustaceans such as crabs, shrimp, mussels, and lobsters. The main natural source of chitosan is the shells of these crustaceans.…”

“…PVAc is produced by polymerizing vinyl acetate monomers and it is easily available, inexpensive, and has very few volatile organic components. 14 PVAc has a biodegradability ability and it could be consumed by Penicillium and Aspergillus fungi species after the product's expected lifetime of the product [33][34][35] PVAc is a polymer with relatively low polarity and low water absorption. The presence of abundant ester links on PVAc allows for strong interactions with the hydroxyl-rich surface of cellulose.…”

“…These interactions, through hydrogen bonding, are expected to significantly enhance the interface and have a positive impact on the mechanical properties of the materials. 14,36 Studies have shown that blending chitosan with PVAc can improve the mechanical properties and water resistance of the resulting composite material. The compatibility between the two polymers was found to be enhanced by introducing carboxylate or sulfonate groups onto the chitosan backbone, which can form stronger ionic interactions with the PVAc.…”