Effect of temperature and cross-linking density on rheology of chemical cross-linked guar gum at the gel point

Sandolo, Chiara; Matricardi, Pietro; Alhaique, Franco; Coviello, Tommasina

doi:10.1016/j.foodhyd.2008.01.001

Cited by 68 publications

(41 citation statements)

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“…Given the fact that modified polysaccharide has more stability against enzyme than its natural form, more attention has been paid, particularly to a cross-linked polysaccharide which is known to have a lower swelling property than its natural form [8,9]. Gliko-Kabir et al showed that the swelling property of guar gum was reduced significantly after being cross-linked with glutaraldehyde [10].…”

Section: Introductionmentioning

confidence: 99%

Incorporation of Vitamin E Onto Cross-Linked Galactomannan Phosphate Matrix and in Vitro Study

Tarigan

Purba

Zuhra

2018

Asian J Pharm Clin Res

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Objective: This study demonstrated the incorporation of Vitamin E from palm fatty acid distillate onto crosslinked galactomannan phosphate (CGP) matrix.Methods: CGP was obtained from the crosslinking reaction of galactomannan from Arenga pinnata (GAP) with tri-sodium metaphosphate (TMF) ranging from 1:1 to 4:3 while incorporation of Vitamin E was conducted in two steps to form films. The reliability study of Vitamin E in CGPVE was conducted using a solution of pepsin and sodium chloride and also in solution of pancreatin and buffer phosphate. Results:The Fourier-transform infrared spectrum indicated the presence of phosphate in CGP while the scanning electron microscope images depicted the changes of surface morphology from smooth (GAP) to rough and hollow (CGP) which confirmed that crosslink had occurred. The swelling study of CGP showed that the swelling indexes were similar and decreased with the increase of TMF. The efficiency of CGP to absorb Vitamin E ranged from 89.66% to 91.09%. The in vitro releasing study of Vitamin E in simulated gastric fluid and simulated intestinal fluid showed that only a small amount of Vitamin E was released.Conclusions: This study demonstrated that CGP can be prepared and is potentially useful for drug delivery to the colon.

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Section: Introductionmentioning

confidence: 99%

Incorporation of Vitamin E Onto Cross-Linked Galactomannan Phosphate Matrix and in Vitro Study

Tarigan

Purba

Zuhra

2018

Asian J Pharm Clin Res

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“…It is interesting to note that both, GG and SCLG, interact with borax leading to a three-dimensional network that, besides the intrinsic differences between the two polymers (see below), shows a peculiar anisotropic elongation during swelling, when tablets of these two systems are prepared. In particular, GG and SCLG show important different characteristics: (a) GG dissolves in water as a random coil while SCLG exhibits a triple helix conformation in aqueous solution with a persistence length of about 200 nm [10,25]; (b) borax promotes a rapid gelation of GG [26] by means of crosslinks characterized by a lifetime of the order of seconds [27], leading to self-healing properties of the network. On the other side, SCLG requires several hours for gelation in the presence of borax and no self-healing occurs.…”

Section: Introductionmentioning

confidence: 99%

Guar gum/borax hydrogel: Rheological, low field NMR and release characterizations

Coviello¹,

Matricardi²,

Alhaique³

et al. 2013

Express Polym. Lett.

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Abstract. Guar gum (GG) and Guar gum/borax (GGb) hydrogels are studied by means of rheology, Low Field Nuclear Magnetic Resonance (LF NMR) and model drug release tests. These three approaches are used to estimate the mesh size (!) of the polymeric network. A comparison with similar Scleroglucan systems is carried out. In the case of GGb, the rheological and Low Field NMR estimations of ! lead to comparable results, while the drug release approach seems to underestimate !. Such discrepancy is attributed to the viscous effect of some polymeric chains that, although bound to the network to one end, can freely fluctuate among meshes. The viscous drag exerted by these chains slows down drug diffusion through the polymeric network. A proof for this hypothesis is given by the case of Scleroglucan gel, where the viscous contribution is not so significant and a good agreement between the rheological and release test approaches was found. Vol.7, No.9 (2013) 733-746 Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2013.71 * Corresponding author, e-mail: mariog@dicamp.univ.trieste.it © BME-PT mation in aqueous solution and a single coiled disordered conformation in methylsulphoxide or at high pH values (NaOH$>0.2 M) [10,11]. Due to its peculiar properties, SCLG was extensively used for various commercial applications (secondary oil recovery, ceramic glazes, food, paints, cosmetics, etc.) [12] and it was also investigated for modified/ sustained release formulations and ophthalmic preparations [13]. Actually, it is well known that borax is an efficient crosslinker for polymers bearing hydroxyl groups but the type of formed linkages is still debated and so far two main models have been proposed. The most popular one implies the existence of pure chemical crosslinks between the polymeric chains and borax [14], and it was proposed for the GG/ borax interactions. According to the other model, the borax ions hold together the polymeric chains by means of mixed physical/chemical linkages. This model was firstly proposed for poly-(vinylalcohol) [15] and it was recently suggested also for SCLG [16,17]. The considerable effort devoted to the study of polymer-ion complexes is due to the wide range of application of these systems. In particular, the complex between GG and borate was previously studied by several authors [18,19] that investigated the effect of polymer and borate concentration, temperature, environmental pH conditions, and GG molecular weight on the peculiar rheological properties detected by the frequency dependence of relaxation spectra. Furthermore, a detailed study of the crosslinking reaction of borate ion with polyhydroxy polymers was carried out by means of 11 Keywords: polymer gels, rheology, low field NMR, transport processes, mesh-size eXPRESS Polymer Letters

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“…Other systems present rather low gel concentrations. 40 In this work, the ''apparent'' power-law exponent n was determined by three methods: 22,41 (1) by considering the region where the two moduli are parallel (same n slope ); (2) by determining the intersection of tan d curves along the frequency window (n tan ); and (3) by using eqs. (1) and (2);.…”

Section: Determination Of the Gelation Pointmentioning

confidence: 99%

“…9,11,12,17,[20][21][22][23] These values of the loss tangent were taken in a range of frequency when plotted with time may converge to the gelation time t gel . This criterion has been proved to be very useful since the key variable for describing the gelation point becomes independent of frequency and diverges at this point.…”

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confidence: 99%

Rheological characterization of the gel point in polymer‐modified asphalts

Vargas

Manero

2010

J of Applied Polymer Sci

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In this work, the rheological characterization of the gel point in polymer-modified asphalts is carried out. The viscoelastic properties of polymer-modified asphalts, in which the polymer is styrene-ethylene butylene-styrene (SEBS) with grafted maleic anhydride (MAH), were measured as a function of MAH concentration. The crosslinking reaction that leads to gelation is characterized by power-law frequency-dependent loss and storage modulus (G 00 and G 0 ). The relaxation exponent n (a viscoelastic parameter related to the cluster size of the gel) and gel strength S (related to the mobility on the crosslinked chain segments) were determined. The value of the power-law exponents depends on the composition of polymer, ranging from 0.30 to 0.56, while the value of the rigidity modulus at the gelation point (S) increases with the amount of reactive groups of the modifier polymer. Both n and S are temperature-dependent in the blends. The blends containing gels present a coarse morphology, which is related to the rheological properties of the matrix and dispersed phase.

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Effect of temperature and cross-linking density on rheology of chemical cross-linked guar gum at the gel point

Cited by 68 publications

References 50 publications

Incorporation of Vitamin E Onto Cross-Linked Galactomannan Phosphate Matrix and in Vitro Study

Incorporation of Vitamin E Onto Cross-Linked Galactomannan Phosphate Matrix and in Vitro Study

Guar gum/borax hydrogel: Rheological, low field NMR and release characterizations

Rheological characterization of the gel point in polymer‐modified asphalts

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