Abstract: Processes for recovering natural rubber from an aqueous natural rubber latex that contains extractables and one or more additives and that is essentially free of lignocellulosic plant material are described. Natural rubber in the latex is separated from the water. Preferably, the amount of non-rubber extractables in the natural rubber is reduced by one or more extraction steps yielding a dried natural rubber.

Abstract: A rubber-based pressure-sensitive adhesive composition comprising a rubbery polymer, and a natural rubber having a weight-average molecular weight of from 100,000 to 400,000, wherein the amount of the natural rubber is 5 parts by weight or more and less than 100 parts by weight, based on 100 parts by weight of the rubbery polymer.

Abstract: Disclosed is a method and apparatus for the extraction of high molecular weight biopolymers from plants. Specifically, invention described herein relates to the commercial processing of plant material, including that from desert plants native to the southwestern United States and Mexico, such as the guayule plant (Parthenium argentatum), for the extraction of biopolymers, including natural rubbers. More specifically, the invention relates to laboratory to commercial scale extraction of high molecular weight biopolymers from plant materials including the chemical and mechanical processing of the plants and purification of the extracted biopolymer.

Abstract: There are provided natural rubber free from substances which cause Type I allergy, a rubber compositions having good processability and physical properties which comprises the natural rubber and other rubber, and a tire product comprising the natural rubber. The natural rubber of the present invention exhibits the above properties by containing substantially no proteins specified by the bands of 14, 31 and 45 kDa by SDS-PAGE.

Abstract: Improved matrices and adhesives for tissue repair comprising a biocompatible, bioerodable polymer, said polymer comprising a thermoplastic lactide-containing terpolymer of monomer units derived from lactic acid, glycolic acid, and either caprolactone or valerolactone, which has a water solubility of about 0.01 to about 500 mg/mL at about 25° C. and adhesive strength of about 600 to about 150,000 Pa. The matrix or adhesive can further comprise a filler or a bioactive agent, or both.

Abstract: A method of preparing a low allergic natural rubber latex which is less likely to cause allergy, comprising adding a protease having an exopeptidase activity to a natural rubber latex and aging the natural rubber latex, thereby to decompose a protein in the latex to such a degree that the protein and a protein decomposition product, which have a number-average molecular weight of 4500 or more, are not detected; a method of preparing a deproteinized natural rubber latex which is less likely to cause allergy, comprising adding an alkali protease to a natural rubber latex, thereby to decompose a protein in the latex, adding a protease having an exopeptidase activity, thereby to further decompose the protein and a decomposition product thereof in the latex, and removing the protein and the decomposition product thereof; a low allergic natural rubber obtained by a decomposition treatment of a protein, wherein the protein and a protein decomposition product, which have a number-average molecular weight of 4500 or m

Abstract: A deproteinized natural rubber substantially free from any protein and a process for producing the same which comprises treating a latex with a protease and a specific surfactant or a combination of specific surfactants and separating rubber particles are disclosed. A method for elevating the green strength of a natural rubber and a method for lowering the green strength of a natural rubber are also disclosed. Furthermore, a means for preventing allergy induced by natural rubber is also disclosed.

Abstract: A process for producing a natural rubber for a pressure-sensitive adhesive, which comprises decreasing a molecular weight of an unmasticated natural rubber by the action of a peptizing agent while dissolving the unmasticated natural rubber in an organic solvent, and a natural rubber-based pressure-sensitive adhesive composition comprising a natural rubber having a weigh average molecular weight Mw of 700,000 or less obtained by the process.

Abstract: Improved matrices for tissue repair comprising a biocompatible, bioerodable polymer which has a water solubility of about 0.01 to about 500 mg/mL at about 25° C. and adhesive strength of about 600 to about 150,000 Pa; and pressure sensitive adhesives for tissue repair which have adhesive strength of about 600 to about 150,000 Pa. The matrix or adhesive can further comprise a filler or a bioactive agent, or both. The matrices and adhesives are tissue-adherent and dough-like so they can be molded to fit a repair site. When used for bone/implant fixation, or as a filler for bone or cartilage repair, gradual short-term bioerosion of the adhesive matrix allows it to be replaced with developing bone or cartilage tissue. When used for release of a bioactive agent, the agent can be mixed into the adhesive matrix well before the implantation procedure. After implantation, the bioactive agent is gradually released as the adhesive matrix biodegrades.

Abstract: Disclosed are a deproteinizing agent comprising a proteolytic enzyme and one or more cationic surfactants selected from the group consisting of an alkylamine salt, an alkylamine derivative and quaternized compounds thereof; and a method of preparing a cationic deproteinized natural rubber latex, which comprises adding said deproteinizing agent to a field latex or an ammonia-treated latex thereby subjecting the latex to a deproteinization treatment and purifying the rubber particles in the latex.

Abstract: Natural rubber products are made from fig tree (Ficus carica) by homogenizing the plants in an acetone/benzene and separating the rubber-containing phase by centrifugation. F. carica contains about 4% (w/v) natural rubber in latex, and 0.3, 0.1 and 0.1 % in bark, leaf and fruit, respectively. Molecular mass of the natural rubber from F. carica is about 128 kD. The latex serum of F. carica contains only a small numbers of proteins, with a 48 kD and a 25 kD protein as major proteins. Similar to Hevea brasiliensis and Parthenium argentatum Gray, proteins participating in rubber biosynthesis of F. carica are tightly associated with the rubber particles. Natural rubber is made using the latex serum and the proteins in latex, leaf, bark, and fruit of F. carica.

Abstract: A pressure-sensitive adhesive comprises an elastomer having a partially oriented and partially crystallized elastomer component. Articles comprising the pressure-sensitive adhesive on a backing or substrate are also disclosed, as are methods of preparing the adhesive and the articles.

Abstract: A process for the manufacture of devulcanized rubbers from a base material composed of scrap rubber products is provided which produces high grade, low viscosity rubber products. The process is carried out in at least two stages, the first stage comprising mixing a polymeric additive to the base material at elevated temperatures and the second stage comprising mixing unvulcanized virgin rubber with the mixture of base material and polymeric additive at elevated temperatures. The process also may comprise a preliminary stage in which a chemically modified epoxidized natural rubber is mixed with the base material at ambient temperature prior to the first stage.

Abstract: A method for extracting polyisoprenes from cells, comprising the steps of contacting the cells with an organic protein-denaturing compound, rupturing the cells to release the polyisoprene from the cells and recovering the polyisoprene. The preferred protein denaturing compound comprises an aqueous solution of a guanidine salt.

Abstract: A process for culturing bacteria is disclosed in which is utilized as a bacterial nutrition a serum byproduced upon treatment of a natural rubber latex. The serum has an ample supply, a low cost, a stable quality and a sufficient activity over a wide variety of bacteria, thus contributing to accelerative growth for aerobic and anaerobic bacteria.

Abstract: Processes are described for the recovery of natural rubber from solutions containing guayule rubber and resins. The resinous rubber is dissolved in a lipophilic solvent such as hexane. The rubber is recovered from the solution in high purity on a heated surface immersed in the solution.