Poly-P-cellulose

Layers of cellulose ion-exchangers are prepared with the usual commercial spreaders. A mixture is made of water or the solvent to be used, and about 10—20% cellulose powder. The amount of powder depends on the swelling tendency of the particular powder. The exchangers CM-, DEAE- and ECTEOLA-ceUulose tend to swell considerably PEI- and Poly-P-cellulose only slightly. This swelling is disadvantageous in that the completely dry layer shows a greater or lesser number of very fine cracks. 

Besides these chemically bonded residues, it is possible to form stationary phases for ion-exchange chromatography based on cellulose by impregnation. Examples of this are the polyethylene inline (PEI) and the polyphosphate (Poly-P) celluloses. The cellulose exchangers discussed here have to be distinguished based on their use for an anion- or cation-exchange mechanism. Suitable for the... 

Graft copolymers of nylon, protein, cellulose, starch, copolymers, or vinyl alcohol have been prepared by the reaction of ethylene oxide with these polymers. Graft copolymers are also produced when styrene is polymerized by Lewis acids in the presence of poly-p-methoxystyrene. The Merrifield synthesis of polypeptides is also based on graft copolymers formed from chloromethaylated PS. Thus, the variety of graft copolymers is great. 

Among other in vitro enzymatic polymerizations that have been studied are the oxidative polymerizations of 2,6-disubstituted phenols to poly(p-phenylene oxide)s (Sec. 2-14b) catalyzed by horseradish peroxidase [Higashimura et al., 2000b] and the polymerization of P-cellobiosyl fluoride to cellulose catalyzed by cellulase [Kobayashi, 1999 Kobayashi et al., 2001],... 

In concluding this section, we should touch upon phase boundary concentration data for poly(p-benzamide) dimethylacetamide + 4% LiCl [89], poly(p-phenylene terephthalamide) (PPTA Kevlar)-sulfuric acid [90], and (hydroxy-propyl)cellulose-dichloroacetic acid solutions [91]. Although not included in Figs. 7 and 8, they show appreciable downward deviations from the prediction by the scaled particle theory for the wormlike hard spherocylinder. Arpin and Strazielle [30] found a negative concentration dependence of the reduced viscosity for PPTA in dilute Solution of sulfuric acid, as often reported on polyelectrolyte systems. Therefore, the deviation of the Ci data for PPTA in sulfuric acid from the scaled particle theory may be attributed to the electrostatic interaction. For the other two systems too, the low C] values may be due to the protonation of the polymer, because the solvents of these systems are very polar. 

Notwithstanding this great variety of mechanical properties the deformation curves of fibres of linear polymers in the glassy state show a great similarity. Typical stress-strain curves of poly(ethylene terephthalate) (PET), cellulose II and poly(p-phenylene terephtha-lamide (PpPTA) are shown in Fig. 13.89. All curves consist of a nearly straight section up to the yield strain between 0.5 and 2.5%, a short yield range characterised by a decrease of the slope, followed by a more or less concave section almost up to fracture. Also the sonic modulus versus strain curves of these fibres are very similar (see Fig. 13.90). Apart from a small shoulder below the yield point for the medium- or low-oriented fibres, the sonic modulus is an increasing, almost linear function of the strain. 

Zhu, J. Wang, W.T. Wang, X.L. Li, B. Wang, Y.Z. Green synthesis of a novel biodegradable copolymer base on cellulose and poly(p-dioxanone) in ionic liquid. Carbohydr. Polym. 2009, 76 (1), 139-144. 

Poly(alkyl cyanoaaylate) Polydysine) derivatives Polydactic acid) Polydactide-co-glycolide) Poly(P-hydroxy butyrate) Ethyl cellulose Poly(alkyl methacrylate) Polydactic add) Polydactide-co-glycoUde) Poly(l -caprolactone) Cellulose acetate phthalate Poly(alkyl methacrylate) Ethyl cellulose Polydactic acid) Polydactide-co-glycolide) Albumin Casein Gelatin... 

Rapid cellulose dissolution in anhydrous phosphoric acid is the basis for the Akzo phosphoric acid process [36,74]. A similar concept has been practiced for making Kevlar fibers, in which anhydrous sulfuric acid is used to dissolve poly(p-phenylene terephthalamide). However, anhydrous sulfuric acid is highly corrosive and is produced by mixing concentrated sulfuric acid with small amounts of fuming sulfuric acid. 

FI G U RE 10.44 Clearing temperature (Tc) as a function of polymer concentration for cellulose (DP = 800) in anhydrous phosphoric acid (74.4% w/w P2O5, solid circles). (From Boerstoel, H., Liquid Cystalline Solutions of Cellulose in Phosphoric Acid for Preparing. Cellulose Yarns, Ph.D. dissertation, University of Groningen, 1998.). Open circles represent the clearing temperature for poly(p-phenylene terephthalamide) (M, = 31,000 g/mol) in sulfuric acid (From Picken, S.J., Macromolecules, 22, 1766, 1989.). The square represents the clearing temperature for chitin (Af = 400,000 g/mol) solution at the polymer concentration of 15.5% w/w. 

Semiflexible polymers—including regular AB type copolymers in which A is rigid while B flexible. Cellulose derivatives belong here, as well as poly(p-hydroxybenzoic acid) (PHB), and for instance poly(p-phenylene terephtha-lamide). They are of course stronger than flexible polymers, but their processing is more difficult. 

Belgacem MN, Bataille P, Sapieha S (1994) Effect of corona modification on the mechanical properties of poly propylene/cellulose. Compos J Appl Polym Sci 53 379-385... 

This is a simple two-step process for the fabrication of nanoparticles. The first step is polymeric emulsification in an aqueous medium. The second step is solvent evaporation from the polymer and nanoparticle precipitation. Finally, the nanoparticles are collected by ultracentrifugation and washed with distilled water for the removal of excess stabilizer and lyophUization [23]. The various types of polymer used include poly(lactic-co-glycolic acid) (PLGA), poly-D,L-lactic acid (PLA), poly(E-caprolactone) (PCL), ethyl cellulose, poly(P-hydroxybutyrate), cellulose acetate phthalate, etc. 

Crystallization of poly(P-hydroxybutyrate) was enhanced by cellulose crystals. Nucleation constant for pure PHB was 4.99x10 and 4.88x10 for PHB containing 2 wt%... 

Biodegradable polymers can be classified into three categories according to their origin (i) synthetic polymers, particularly aUphatic polyesters, such as poly (L-lactide) (PLA) [1-3], poly(e-caprolactone) (PCL) [4—6], poly(p-dioxanone) (PPDO) [7-9], and poly(butylene succinate) (PBS) [10-12] (ii) polyesters produced by microorganisms, which mainly correspond to different poly(hydroxyalkanoate)s (e.g., poly(P-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) and (iii) polymers derived from natural resources (e.g., starch, cellulose, chitin, chitosan, lignin, and proteins). 

In this report we present a model for the primary creep of well-oriented aramid fibres. It has been shown for well-oriented fibres of PET, cellulose and poly-(p-phenylene terephthalamide), abbreviated here as PpPTA, that the dynamic compliance, S, is a linear function of the second moment of the orientation distribution of the chains / / /2/ /3/. By measuring S during creep and relaxation of a fibre, the changes in the orientation distribution can be followed. As shown here, such an experiment offers a valuable tool for the investigation of the viscoelasticity in polymer fibres. 

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