Composite sheets with biodegradable polymers and paper, the effect of paper strengthening agents on strength enhancement, and an evaluation of biodegradability

Composite sheets composed of biodegradable polymers (BP) and paper were prepared, and their physical and biodegradable properties were investigated. The paper sheets were soaked in BP emulsions and cured at 100 degrees C for 20 min. The wet strength of composite sheets with the same basis weight increased significantly with increasing BP content, although dry strength increased only moderately. A 0.5% addition of a common wet paper-strengthening agent, poly(amidoamine-epichlorohydrin) (PAE) resin, enhanced the wet strength, which reached 9.3 MPa, of composite sheets consisting of a BP: paper ratio of 20:80. Further enhancement was achieved by the addition of polyvinylamines (PVAm). The wet tensile strength of composite sheets consisting of BP and paper (20: 80) increased by 27% with the addition of 0.2% PVArn and 0.5% PAE, whereas it was enhanced by only 3-4% with the addition of 0.7% PAE. The biodegradability of the composite sheets was somewhat retarded by the addition of PAE and PVAm. However, a 90% weight loss was observed 60 days after placing composite sheet samples in soil. A similar weight loss was observed after 45 days for composites without additives and after 30 days for base paper alone. (c) 2005 Wiley Periodicals, Inc.