Rubberlike Products from Linear Polyesters

1948 ◽  
Vol 21 (1) ◽  
pp. 115-132
Author(s):  
B. S. Biggs ◽  
R. H. Erickson ◽  
C. S. Fuller
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Chemical Structure ◽  
Dibasic Acid ◽  
News Article ◽  
Structure And Properties ◽  
Factors Affecting ◽  
Chain Molecules ◽  
Synthetic Rubber ◽  
Rubberlike Materials

Abstract The polymers which result from the condensation of dibasic acids with propylene glycol are viscous gums which can be vulcanized to rubberlike products. In the unpigmented condition these rubbers are quite weak, but when reinforced with suitable pigments their strength and elongation compare favorably with other synthetic rubbers. Because polyesters of known structure and molecular weight can be easily synthesized, these polymers are useful for the study of the relations between structure and properties in rubberlike materials in general. Factors affecting tensile strength, oil resistance, brittle temperature, and stability are discussed. The development of rubberlike products from linear polyesters was announced in a short news article more than three years ago, but a detailed description of their preparation and physical properties has not been published. The object of this paper is to review these properties. However, the paper is written not so much from the viewpoint of offering a synthetic rubber for practical use as from that of applying linear polyesters to the study of the relations between structure and properties of rubberlike substances in general. As has been pointed out in other articles, the linear polyesters are well suited to serve as models in such a study, since molecules of definitely known constitution and molecular-weight distribution can be synthesized by relatively simple methods. Furthermore, the chemical structure of the polyester chain molecules can be varied in a definite and controlled manner by the choice of suitable glycol and dibasic acid or hydroxy acid reactants. The structure of the chains in the case of the former, assuming equal molar proportions, may be represented by the general formula:

EFFECT OF PLASTICIZER EXTRACTION BY JET FUEL ON A NITRILE HOSE COMPOUND

2015 ◽  
Vol 88 (2) ◽  
pp. 324-342 ◽  
Author(s):  
Richard J. Pazur ◽  
T. A. C. Kennedy
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Glass Transition ◽  
Chemical Structure ◽  
Jet Fuel ◽  
Butadiene Rubber ◽  
Maximum Torque ◽  
Lower Viscosity ◽  
Aromatic Components ◽  
Polymeric Plasticizer

ABSTRACT Seven ester plasticizers were evaluated in a reference acrylonitrile–butadiene rubber (NBR) fuel hose compound with respect to extractability resistance to jet fuel. Plasticizers differed primarily in chemical structure (polarity) and molecular weight (monomeric vs polymeric). Plasticizer addition led to lower viscosity, maximum torque, modulus, tensile strength, and enhanced low temperature properties. Exposure to jet fuel caused plasticizer extraction resulting in compound softening due to absorption of the aromatic components in the fuel. The glass transition temperature shifted toward lower temperatures. Extraction resistance is enhanced by optimizing polymer–plasticizer compatibility and by using a higher molecular weight plasticizer. The use of the polymeric plasticizer A-8600 lowers the loss of other fugitive plasticizers, indicating the presence of specific plasticizer–plasticizer interactions. Of the monomeric and polymeric plasticizers, trioctyl trimellitate and A-8600, respectively, display the best combination of plasticizing ability and extraction resistance.

The Effect of Triacetin on the Plasticization Efficiency and Tensile Properties of Polyvinyl Chloride/di-2-Ethyl Hexyl Phthalate/Triacetin Compounds

2016 ◽  
Vol 1133 ◽  
pp. 206-210 ◽  
Author(s):  
Arjulizan Rusli ◽  
Nur Farhana Asul Kahar
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Glass Transition ◽  
Tensile Properties ◽  
Polyvinyl Chloride ◽  
Chemical Structure ◽  
Low Molecular Weight ◽  
Migration Ability ◽  
Elongation At Break ◽  
Before And After

The use of triacetin as an alternative plasticizer to polyvinyl chloride (PVC) was studied in term of plasticizer efficiency and tensile properties before and after ageing. The efficiency of plasticizers was evaluated based on the glass transition temperature (Tg) and the hardness value of the compounds. The Tg and hardness of all PVC/DEHP/Triacetin compounds are lower than PVC/50DEHP and PVC/50Triacetin compounds indicating synergistic plasticisation effect between both DEHP and Triacetin within the PVC compounds. The low molecular weight and chemical structure of triacetin are believed to contribute to the highest tensile strength, elongation at break and modulus of the PVC/triacetin compared with PVC/DEHP and PVC/DEHP/triacetin compounds. However, the migration ability of the triacetin plasticizer is believed to result in the biggest changes of the tensile properties of PVC compounds plasticized with triacetin before and after ageing.

Factors Affecting Bioconcentration of Trace Organic Contamination in Waters

1989 ◽  
Vol 21 (2) ◽  
pp. 147-150 ◽  
Author(s):  
D. W. Hawker ◽  
D. W. Connell
Keyword(s):  
Molecular Weight ◽  
Bioconcentration Factor ◽  
Aqueous Solubility ◽  
Organic Chemicals ◽  
Organic Contamination ◽  
Hydrophobic Organic Chemicals ◽  
Factors Affecting ◽  
Water Partition Coefficient ◽  
Physicochemical Factors ◽  
Trace Organic

The influence of some important biological and physicochemical factors on the bioconcentration of hydrophobic organic chemicals is outlined. For non-ionizable, persistent compounds the bioconcentration factor can be related to a compound's octanol/water partition coefficient, aqueous solubility and molecular weight, while the lipid content of an organism also affects the bioconcentration potential of these compounds. The effect of ionization and biodegradation of organic chemicals on bioconcentration is also discussed.

scholarly journals Melt- vs. Non-Melt Blending of Complexly Processable Ultra-High Molecular Weight Polyethylene/Cellulose Nanofiber Bionanocomposite

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 404
Author(s):  
Nur Sharmila Sharip ◽  
Hidayah Ariffin ◽  
Tengku Arisyah Tengku Yasim-Anuar ◽  
Yoshito Andou ◽  
Yuki Shirosaki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
Yield Strength ◽  
Young’S Modulus ◽  
High Molecular Weight ◽  
Melt Processing ◽  
Cellulose Nanofiber ◽  
Melt Blending ◽  
Ultra High Molecular Weight

The major hurdle in melt-processing of ultra-high molecular weight polyethylene (UHMWPE) nanocomposite lies on the high melt viscosity of the UHMWPE, which may contribute to poor dispersion and distribution of the nanofiller. In this study, UHMWPE/cellulose nanofiber (UHMWPE/CNF) bionanocomposites were prepared by two different blending methods: (i) melt blending at 150 °C in a triple screw kneading extruder, and (ii) non-melt blending by ethanol mixing at room temperature. Results showed that melt-processing of UHMWPE without CNF (MB-UHMWPE/0) exhibited an increment in yield strength and Young’s modulus by 15% and 25%, respectively, compared to the Neat-UHMWPE. Tensile strength was however reduced by almost half. Ethanol mixed sample without CNF (EM-UHMWPE/0) on the other hand showed slight decrement in all mechanical properties tested. At 0.5% CNF inclusion, the mechanical properties of melt-blended bionanocomposites (MB-UHMWPE/0.5) were improved as compared to Neat-UHMWPE. It was also found that the yield strength, elongation at break, Young’s modulus, toughness and crystallinity of MB-UHMWPE/0.5 were higher by 28%, 61%, 47%, 45% and 11%, respectively, as compared to the ethanol mixing sample (EM-UHMWPE/0.5). Despite the reduction in tensile strength of MB-UHMWPE/0.5, the value i.e., 28.4 ± 1.0 MPa surpassed the minimum requirement of standard specification for fabricated UHMWPE in surgical implant application. Overall, melt-blending processing is more suitable for the preparation of UHMWPE/CNF bionanocomposites as exhibited by their characteristics presented herein. A better mechanical interlocking between UHMWPE and CNF at high temperature mixing with kneading was evident through FE-SEM observation, explains the higher mechanical properties of MB-UHMWPE/0.5 as compared to EM-UHMWPE/0.5.

Coactivation of Delayed-Action Vulcanization. Part I. Polymeric, Nonmigratory Cure Coactivators for Accelerated Sulfur Vulcanization

1989 ◽  
Vol 62 (5) ◽  
pp. 957-972
Author(s):  
A. Y. Coran ◽  
F. Ignatz-Hoover ◽  
L. H. Davis
Keyword(s):  
Molecular Weight ◽  
Minimum Loss ◽  
Synthetic Rubber ◽  
Curing Characteristics ◽  
Sulfur Vulcanization ◽  
Delayed Action ◽  
Very High ◽  
Rubber Article

Abstract Rubbery vinylpyridine-butadiene copolymers, containing 20–65% by weight of vinylpyridine monomer units, are effective coactivators of vulcanization for TBBS-accelerated sulfur-vulcanized SBR. In addition to emulsion SBR, the new co-activator has been evaluated in copositions of solution SBR, BR, NR, and various blends. The co-activator is active in all of the compositions which contain butadiene-derived synthetic rubber. This includes blends such as SBR/BR, solution-SBR/BR, SBR/NR, BR/NR, SBR/BR/NR, etc. There is little or no activity in which NR is the only polymer. The most efficacious copolymers contain between 30 and 60% 2-vinylpyridine. The incorporation of such a copolymer into an unvulcanized butadiene-derived rubber mix can give a substantial increase in the rate of crosslink formation with only a minimum loss of scorch resistance. Since the polymeric coactivators are very high in molecular weight, it can be at least tentatively concluded that they will not migrate from one component stock to another in a built-up multi-stock rubber article, either before or during vulcanization. Since the curing characteristics of a vinylpyridine-copolymer-containing TBBS-accelerated stock can be similar to those of TBBS-accelerated NR, it might be concluded that the new additives will solve some of the problems in balancing the cures of adjacent NR and SBR stocks in a multicomponent cured rubber article.

scholarly journals Evaluation of Binders in Twin-Screw Wet Granulation

Pharmaceutics ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 241
Author(s):  
Claudia Köster ◽  
Sebastian Pohl ◽  
Peter Kleinebudde
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Wet Granulation ◽  
Compression Pressure ◽  
Demineralized Water ◽  
Twin Screw

The binders povidone (Kollidon 30), copovidone (Kollidon VA64), hypromellose (Pharmacoat 606), and three types of hyprolose (HPC SSL-SFP, HPC SSL, and HPC SL-FP) were evaluated regarding their suitability in twin-screw wet granulation. Six mixtures of lactose and binder as well as lactose without binder were twin-screw granulated with demineralized water at different barrel fill levels and subsequently tableted. A screening run with HPC SSL determined the amount of water as an influential parameter for oversized agglomerates. Subsequent examination of different binders, especially Kollidon 30 and Kollidon VA64 resulted in large granules. All binders, except Pharmacoat 606, led to a reduction of fines compared to granulation without a binder. The molecular weight of applied hyproloses did not appear as influential. Tableting required an upstream sieving step to remove overlarge granules. Tableting was possible for all formulations at sufficient compression pressure. Most binders resulted in comparable tensile strengths, while Pharmacoat 606 led to lower and lactose without a binder to the lowest tensile strength. Tablets without a binder disintegrated easily, whereas binder containing tablets of sufficient tensile strength often nearly failed or failed the disintegration test. Especially tablets containing Pharmacoat 606 and HPC SL-FP disintegrated too slowly.

Occurrence of milk proteins in the urine of cows during an extended milking interval

1967 ◽  
Vol 34 (1) ◽  
pp. 27-30 ◽  
Author(s):  
R. L. J. Lyster ◽  
J. V. Wheelock
Keyword(s):  
Molecular Weight ◽  
Milk Proteins ◽  
Immunological Methods ◽  
Factors Affecting ◽  
Β Lactoglobulin

SummaryImmunological methods have been used to test samples of urine from 5 cows for the presence of milk proteins. None could be detected when the cows were milked twice daily at the usual intervals, but during an extended milking interval α-lactalbumin was found in the urine of all 5 cows and β-lactoglobulin in the urine of 2 cows. The urine of one cow during and after a milking interval of 39 h contained 1·63 g α-lactalbumin, 1·12 g β-lactoglobulin and a small amount of casein. One of the factors affecting the transfer of these milk constituents from the udder to the urine appears to be their molecular weight.

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