Cellulose acetate butyrates properties

The cellulose esters with the largest commercial consumption are cellulose acetate, including cellulose triacetate, cellulose acetate butyrate, and cellulose acetate propionate. Cellulose acetate is used in textile fibers, plastics, film, sheeting, and lacquers. The cellulose acetate used for photographic film base is almost exclusively triacetate some triacetate is also used for textile fibers because of its crystalline and heat-setting characteristics. The critical properties of cellulose acetate as related to appHcation are given in Table 10. 

Cellulosic They are tough, transparent, hard or flexible natural polymers made from plant cellulose feedstock. With exposure to light, heat, weather and aging, they tend to dry out, deform, embrittle and lose gloss. Molding applications include tool handles, control knobs, eyeglass frames. Extrusion uses include blister packaging, toys, holiday decorations, etc. Cellulosic types, each with their specialty properties, include cellulose acetates (CAs), cellulose acetate butyrates (CABs), cellulose nitrates (CNs), cellulose propionate (CAPs), and ethyl celluloses (EC). 

Polymer blends have been categorized as (1) compatible, exhibiting only a single Tg, (2) mechanically compatible, exhibiting the Tg values of each component but with superior mechanical properties, and (3) incompatible, exhibiting the unenhanced properties of phase-separated materials (8). Based on the mechanical properties, it has been suggested that PCL-cellulose acetate butyrate blends are compatible (8). Dynamic mechanical measurements of the Tg of PCL-polylactic acid blends indicate that the compatability may depend on the ratios employed (65). Both of these blends have been used to control the permeability of delivery systems (vide infra). 

Systematic investigations were carried out for the preparation of cellulose acetate of D.S. 2,65 and other mixed esters which included cellulose acetate-propionate, cellulose acetate-butyrate, cellulose acetate-benzoate and cellulose acetate-methacrylate. The experimental conditions were optimised for maximum yield of the ester. Flat osmotic membranes were developed from these esters and characterised for their osmotic and transport properties. The nmmbra-nes were evaluated in a reverse osmosis laboratory test-cell using 5OOO ppm sodium chloride solution at 40 bars pressure. Table 1 presents the typical performance data of these membranes. 

These two cellulose esters are somewhat similar in properties and applications. Cellulose acetate butyrate is commonly referred to in the chemical industry as CAB. while cellulose acetate propionate is simply termed cellulose propionate" and referred to as CAP or as CP. 

To improve the thermal, mechanical, and viscoelastic properties of cellulose acetate butyrate, it was reinforced with nanocellulose crystals prepared from BC by acid hydrolysis. Using this nanosized cellulose (Sect. 1) a significant improvement in the properties of the composites was demonstrated [57]. 

Table IV. Properties of Typical Commercial Grades of Cellulose Acetate-Butyrate for Adhesive Application...

Abstract This article summarizes a large amount of work carried out in our laboratory on polysiloxane based Interpenetrating Polymer Networks (IPNs). First, a polydimethylsiloxane (PDMS) network has been combined with a cellulose acetate butyrate (CAB) network in order to improve its mechanical properties. Second, a PDMS network was combined with a fluorinated polymer network. Thanks to a perfect control of the respective rates of formation of each network it has been possible to avoid polymer phase separation during the IPN synthesis. Physicochemical analyses of these materials led to classify them as true IPNs according to Sperling s definition. In addition, synergy of the mechanical properties, on the one hand, and of the surface properties, on the other hand, was displayed. 

First, PDMS network was combined to a cellulose acetate butyrate (CAB) network into an IPN architecture in order to improve the thermomechanical properties of PDMS network (Scheme 1). The linear CAB can be cross-linked through its free OH groups with a Desmodur N3300 pluri-isocyanate. The alcohol/isocyanate reaction is catalyzed by DBTDL leading to urethane cross-links. Simultaneously, PDMS oligomers must be cross-linked independently in order to form the PDMS network. In order to carry out independent cross-linking reactions. 

It should be expected that calculated values of 6jjp correlate better with equilibrium properties of the membranes in aqueous solution than with transport properties. Che of the few such equilibrium measurements that have been published is by Anderson et al (.2J). Their measured partition coefficients (K), diffusion coefficients (D), and reverse osmosis rejection (R) of the organic solutes are shown in Table III for cellulose acetate membranes. Their data for cellulose acetate butyrate was similar and is not shown here. Aqueous solutions of the organic solutes, usually at concentrations of about 10 g 1 , were used in the measurement of partition coefficients by UV absorption. In Table III,... 

The cellulose acetate propionates are Intermediate in properties between the cellulose acetates and the cellulose acetate butyrates, resembling the cellulose acetate butyrates in solubility and compatibility. Like the acetates, the propionates have practically no odor and thus can be used in applications where low odor is a requirement. These properties make the propionates especially useful in inks, overprints, plastic, and paper coatings, and various reprographic processes. CAP-482-0.5 requires moderately strong solvents to effect solution (Table VI). 

Dimethyl phthalate (DMP) also has high dissolving capacity for CN. It has good compatibility with cellulose esters and are used in celluloid made fi-om CN and plastic compounds or films made from other cellulosic polymers, cellulose acetate (CA), cellulose acetate-butyrate (CAB), cellulose acetate-propionate (CAP), and cellulose propionate (CP). It is light stable but highly volatile. Diethyl phthalate (DEP) possesses properties similar to DMP and is slightly less volatile. 

Cellulose acetate-butyrate (CAB) has several advantages in properties over cellulose acetate lower moisture absorption, greater solubility and compatibility with plasticizer, higher impact strength, and excellent dimensional stability. CAB used in plastics has about 13% acetyl and 37% butyryl content. It is an excellent injection-molding material (Tenite Butyrate by Kodak, Cellidor B by Bayer). 

Cellulose butyrate contains the bulkier butyryl group these esters are more compatible and soluble than acetates, but are too soft for most coating applications. Cellulose esterified with blends of alkyl groups can provide many intermediate properties needed in coatings. Selection of the appropriate cellulose acetate butyrate [9004-36-8] (CAB) and cellulose acetate propionate [9004-39-f] (CAP) content must be based on specific application requirements. 

Table 2.2. Properties of cellulose acetate butyrates (CAB) and cellulose acetate propionates (CAP) (Tennessee Eastman)...

Cellulose acetate butyrate is used in a wide variety of coatings for wood because they provide many desirable properties (fast solvent release, flowout, and leveling excellent spray characteristics, nonyellowing, and cold crack resistance). 

---