Effect of crosslink density on the molecular relaxations in diepoxide-diamine network polymers. Part 1. The glassy region

1988 ◽  
Vol 28 (4) ◽  
pp. 221-229 ◽  
Author(s):  
John M. Charlesworth
Keyword(s):  
Crosslink Density ◽  
Network Polymers

A New Derivation of Postgel Properties of Network Polymers

1976 ◽  
Vol 49 (5) ◽  
pp. 1219-1231 ◽  
Author(s):  
D. R. Miller ◽  
C. W. Macosko
Keyword(s):  
General Result ◽  
Crosslink Density ◽  
Polymer Network ◽  
Probability Generating Function ◽  
Finite Chain ◽  
Network Polymer ◽  
Network Polymers ◽  
Property Relations ◽  
Recursive Scheme ◽  
Effective Network

Abstract The probability of a finite or dangling chain on an ideal polymer network has been derived by a simple recursive scheme. In contrast to the method of Dobson and Gordon, probability generating function formalism is not required. The general result, Equations (21), and its specific solutions, Equations (23), (24), and (30), give the finite chain probability as a function of reactant type and extent of polymerization. They cover most of the important types of network forming polymerizations. From the finite chain probability, useful property relations such as sol fraction, crosslink density, and the number of elastically effective network chains are developed. Because of their simplicity, we expect these relations to be further developed and applied to network polymer property measurements.

The Crystallization of Modified Cis-Polybutadiene

1960 ◽  
Vol 33 (3) ◽  
pp. 699-702
Author(s):  
G. S. Trick
Keyword(s):  
Melting Point ◽  
Crosslink Density ◽  
Fixed Temperature ◽  
Trans Isomerization

Abstract From a sample of polybutadiene of high cis-1,4 content, the microstructure is modified by cis-trans isomerization or by crosslinking. Measurements of rates of crystallization and melting point are made on the modified samples. An increase in irons content or crosslink density markedly decreases the rate of crystallization at a fixed temperature. It is found, however, that this retardation in rate may usually be accounted for by the depressed melting point of the modified samples.

Effect and Detection of Loose Chain Ends in Crosslinked Polyurethane Elastomers

1971 ◽  
Vol 44 (1) ◽  
pp. 152-165 ◽  
Author(s):  
A. E. Oberth
Keyword(s):  
Crosslink Density ◽  
Volume Fraction ◽  
Present Theory ◽  
Swelling Ratio ◽  
Polyurethane Elastomers ◽  
Equilibrium Volume ◽  
Equilibrium Swelling ◽  
Volume Swelling

Abstract The effect of loose chain ends on tensile properties and equilibrium swelling of crosslinked polyurethane rubbers is studied. As in plasticized elastomers, tensile strength and elastic modulus are reduced approximately by a factor (1−νE,P)2, where νE,P is the volume fraction of loose chain ends, plasticizer, or both. This effect is much larger than predicted by present theory. Also the equilibrium volume swelling ratio, V0/V, of rubbers having terminal chains or an equal volume of plasticizer is the same, provided they do not differ in crosslink density. However, the volume fraction of “network rubber” in the equilibrium swollen specimen, ν2, differs owing to the non-extractability of terminal chains. On this basis a method is proposed which allows experimental determination of the volume fraction of loose ends. Elastomers abounding in loose chain ends show markedly less long term stress relaxation. This effect is not clearly understood but is useful to detect the presence of non load-bearing network.

scholarly journals PSIII-1 A preliminary study to investigate the contribution of different tenderness factors to beef loin, tri-tip and heel tenderness

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 233-234
Author(s):  
Colin Chun ◽  
Wanjun Wu ◽  
Amelia Welter ◽  
Travis O'Quinn ◽  
Geraldine Magnin ◽  
...  
Keyword(s):  
Muscle Tissue ◽  
Lipid Content ◽  
Crosslink Density ◽  
Troponin T ◽  
Collagen Content ◽  
Aging Period ◽  
Relative Contribution ◽  
Beef Carcasses ◽  
Trained Panel ◽  
Longissimus Lumborum

Abstract The objective of this study was to identify the relative contribution of tenderness factors for 3 beef muscles with similar tenderness ratings. Longissimus lumborum (loin), tensor fascia latae (tri-tip) and gastrocnemius (heel) were collected from 10 USDA choice beef carcasses, fabricated into steaks and assigned to a 5 or 21 d aging period (n=60). Heel had the greatest relative troponin-T degradation %, followed by tri-tip and loin (68.10, 53.42 and 35.01 % respectively; P< 0.01). Tri-tip had the longest sarcomere, followed by heel and loin (3.01, 2.59 and 1.71 µm, respectively; P < 0.01), and heel increased in sarcomere length from 5 to 21 d of postmortem storage (2.49 vs 2.70 µm; P< 0.05). As expected, heel had the greatest collagen content, followed by tri-tip and loin (6.06, 3.98 and 2.76 mg/g of muscle tissue, respectively; P< 0.01), and collagen content decreased for all cuts from 5 to 21 d of postmortem storage (4.64 vs 3.90 mg/g muscle tissue; P< 0.05). Out of the 3 cuts, heel had the highest collagen crosslink density (0.20 mol/mol collagen; P< 0.05), while loin and tri-tip did not differ (0.13 and 0.15 mol/mol collagen, respectively; P >0.05). Collagen crosslink density increased for all cuts from 5 to 21 d of postmortem storage (0.14 vs 0.20; P< 0.01). Heel had lower lipid content than the others (2.68 %; P< 0.01), while tri-tip and loin did not differ in lipid content (8.24 vs. 6.99 %; P >0.05). Loin was ranked by the trained panel to have the highest overall tenderness, while tri-tip and heel did not differ in overall tenderness (P >0.05). The overall tenderness value for heel was positively correlated with troponin-T degradation (P< 0.01). On the other hand, overall tenderness value for loin was negatively correlated with lipid content (P< 0.05), and overall tenderness value for tri-tip was negatively correlated with collagen content (P< 0.05). These results indicated that each beef cut had a unique profile of tenderness contributors.

Sign in / Sign up

Export Citation Format

Share Document