New polyurethane foams modified with cellulose derivatives

doi:10.1016/j.eurpolymj.2004.07.015

European Polymer Journal

Volume 40, Issue 12, December 2004, Pages 2803-2812

https://doi.org/10.1016/j.eurpolymj.2004.07.015 Get rights and content

Abstract

New polyurethane foams were elaborated with different cellulose derivatives as raw material, by the one-shot process. The foams were submitted to soxhlet extraction in order to quantify the amount of cellulose derivative incorporated in the foam by chemical bonding. The foams were characterized by means of FTIR, solid state ¹³C NMR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy and dynamic mechanical analysis (DMA). The FTIR- and solid state ¹³C NMR showed characteristic peaks for cellulose derivatives and polyurethane. DMA measurements indicated that storage modulus increased with increasing content of cellulose derivatives. The highest value was obtained for foams prepared with cellulose sulphate.

Introduction

Polyurethanes (PUs) are usually obtained from reaction between polyfunctional alcohols (polyol polyether or polyol polyester) and polyisocyanate forming urethane linkages. There are various methods for producing PUs according to preparation procedure (solvent-free, in organic solvents). Flexible and rigid foams are prepared mainly by a solvent-free method. The most widely used is the one-shot process, where direct mixing of coreactants and simultaneous addition of a blowing agent, catalysts and other additives are used. Foam properties are affected by the properties of raw materials and also can be modified by a wide variety of additives such as fillers stabilizers, cross-linking agents and chain extenders [16].

Although PUs are materials with a broad variety of applications, the most important are for furniture industry, building construction, transportation and shoe industry, there are some interesting areas where PUs have not been studied thoroughly up to now, such as agricultural and medicinal applications. Both of them have in common that they are discarded after being used, representing contamination problems due to their difficult disintegration and incorporation to the environment. A solution for this problem is to include a natural material in the formulation in order to give some properties like biodegradation and avoid contamination [19], [3].

Compounds containing OH groups may be used as OH providers to modify the PUs properties and structure [16]. Several research works using starch as modifier have been carried out [14], [20], [1], [4], [8], [7], [18]. Other naturals materials like saccharides, cashew nut shell liquid, soybean oil and soy flour have been also used in PU foams preparation [21], [2], [9], [5], [6]. However, research work based on cellulose or cellulose derivatives has been reported very little [18], [10].

There are a variety of cellulose derivatives having different properties such as solubility and thermal behavior. Thus, this study focused on the use of carboxymethyl cellulose (CMC), cellulose sulphate (CS), cellulose acetate (CA) and trimethylsilyl cellulose (TMSC). All of them have free OH groups depending on their degree of substitution (DS), and are capable of reacting in the formation process of PU foams. The influence of number of free OH groups and type of substituent on foam structure and properties was analyzed. The amount of cellulose derivative included in foam was quantified and the thermal and mechanical properties of the foams as well as their structure were studied by means of scanning electron microscopy.

Section snippets

Materials

Commercial products were used as raw materials: a polyol polyether (Arcol F-3020, MW 3000 and OH number 55–58), surfactant Dabco DC5160 based on a copolymer silicon–glycol, a tertiary amine Polycat T-9 as catalyst, 2,4-tolylene diisocyanate 80% TDI, Cellulose Avicel^R PH-101 were used for the preparation of cellulose derivatives. All solvents were chemical grade.

Cellulose derivatives

The cellulose derivatives used were cellulose acetate (CA), carboxymethyl cellulose (CMC), cellulose sulphate (CS) and trimethylsilyl

Preparation of polyurethane (PU) foams

Table 1 shows the characteristics of the cellulose derivatives used for the inclusion in the PU foam. Carboxymethyl cellulose (CMC), cellulose acetate (CA), cellulose sulphate (CS), and trimethylsilyl cellulose (TMSC) were successfully included in the formulation while cellulose carbamate leads to a collapse of the foam during the curing process. This may be caused by the carbamate substituents along the cellulose chain accelerating the reaction of OH groups.

Table 3 summarizes the results of

Conclusions

From IR and solid state ¹³C NMR studies it can be concluded that the inclusion of cellulose derivatives in the PU structure occurs. The differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that there are no changes in thermal properties with exception of foams prepared with CS, delaying thermal decomposition and T_g. The micrographs indicate that foams have a different cell shape for each derivative, producing a change in mechanical properties. DMA analysis

Acknowledgments

The authors are grateful to Consejo del Sistema Nacional de Educación Tecnológica (COsNET) for generous financial support. One of us (J.L.R.A.) wishes to thank the “Deustcher Akademischer Austausch” (DAAD) for a fellowship. The authors are also thankful to Stephanie Hesse (Friedrich Schiller University of Jena, Germany) for the solid state ¹³C NMR analysis and to Dr. Andreas Koschella for helpful discussions.

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New polyurethane foams modified with cellulose derivatives

Abstract

Introduction

Section snippets

Materials

Cellulose derivatives

Preparation of polyurethane (PU) foams

Conclusions

Acknowledgments

Synthesis and characterization of starch-based polyurethane foams

J. Appl. Polym. Sci.

Synthesis of polyurethane from cashew nut shell liquid (CNSL), a renewable resource

J. Polym. Sci., Part A: Polym. Chem.

Degradation of starch–plastic composites in a municipal solid waste landfill

J. Environ. Polym. Degrad.

Glycols in polyurethane foam formulations with a starch–oil composite

J. Appl. Polym. Sci.

Comparative study of physical properties of water-blown rigid polyurethane foams extended with commercial soy flours

J. Appl. Polym. Sci.

Dynamic-mechanical study of water-blown rigid polyurethane foams with and without soy flour

J. Appl. Polym. Sci.

Biodegradable polyurethane materials from bark and starch. I. Highly resilient foams

J. Appl. Polym. Sci.

Rigid polyurethane foams based on soybean oil

J. Appl. Polym. Sci.

Synthesis and hemocompatibilities of cellulose-containing segmented polyurethanes

Macromol. Chem. Phys.