Aromatic polyamides. III. Copoly(4,4′-oxanilideterephthalamide—4,4′-phenyleneterephthalamide): Synthesis,wet-spinning,fiber thermal characterization,and stability in sulfuric acid

Copoly(4,4′-oxanilideterephthalamide—4,4′-phenyleneterephthalamide) (A-202/PPD) was synthesized by reaction of 4,4′-diaminooxanilide, p-phenylenediamine, and terephthaloyl chloride in organic solvents. Copolymer inherent viscosities in H₂SO₄ as high as 10.3 were obtained. Isotropic copolymer solutions (4%—5% concentration) of A-202/40%–80% PPD were spun to fibers with tenacity/elongation/modulus at 1% extension in the 13–14 gpd/1.5%–2%/700–1000 gpd range. Oxamide and amide stabilities in 98–100% H₂SO₄ and 20% oleum were compared. Poly(4,4′-oxanilideterephthalamide) (A-202), A-202/PPD copolymers, and poly(4,4′-phenyleneterephthalamide) (PPT) were unstable in 20% oleum, but all proved relatively stable in 100% H₂SO₄. However, the oxamide linkage proved less stable than the amide linkage in 98% H₂SO₄. A-202 and A-202/PPD copolymers formed stable anisotropic spinning solutions in 1% oleum at 10–20% concentrations. Dynamic mechanical analyses (Vibron) showed no glass transition temperature (T_g) below 200°C. Dilatometric measurement of A-202/50% PPD revealed a T_g at 257°C. Differential thermal analyses of A-202/40–80% PPD exhibited endotherms at 470–480°C. Thermogravimetric analyses showed no significant weight loss below 400°C.     

Aromatic polyamides. II. Synthesis,wet-spinning,and fiber thermal characterization of poly(4,4′-oxanilideterephthalamide) and copolymers with 4,4′-oxydianiline or isophthalic acid

Poly(4,4′-oxanilideterephthalamide) (coded A-202) was prepared from 4,4′-diaminooxanilide (DAO) and terephthaloyl chloride (TCI) in N,N-dimethylacetamide (DMAc)/5% LiCl and DMAc (5% LiCl)/hexamethylphosphorictriamide (HMPA) solvents. Fiber with tenacity/elongation/modulus at 1% extension (t/e/m) of 5.2 grams per denier (gpd)/1.9%/316 gpd was obtained. The all-para A-202 tended to precipitate from solution. More soluble copolyamides were prepared from DAO and TCl in combination with either 4,4′-oxydianiline (A-202/ODA) or isophthaloyl chloride (A-202/I) in DMAc (5%LiCl). A-202/ODA solutions were spun to fiber with t/e/m of 11.2 gpd/6%/217 gpd; A-202/I gave fiber with t/e/m of 6.4 gpd/1.3%/432 gpd. Dynamic mechanical analyses (Vibron) and dilatometric measurements of A-202, A-202/ODA, and A-202/I showed no glass transition temperature below 200°C. Differential thermal analyses (DTA) revealed no transitions below 400°C. Thermogravimetric analyses (TGA) at 15°C/min exhibited substantially no weight loss in air at temperatures up to 400°C.     

Reflection of plane waves from the boundary of a pre-stressed compressible elastic half-space

The effect of pre-stress on the propagation and reflection ofplane waves in an incompressible isotropic elastic half-spacehas been examined recently by the authors (Ogden & Sotiropoulos,1997). In the present paper the corresponding analysis for compressiblematerials is detailed. In the two-dimensional context consideredfor incompressible materials the (homogeneous) plane waves werenecessarily shear waves. By contrast, in the compressible contextpure shear waves can propagate only in specific directions inthe considered principal plane and, in a general direction,a quasi-shear wave may be accompanied by a quasi-longitudinalwave, as is the case in the anisotropic linear theory. The dependenceof the (in-plane) slowness section on the pre-stress (and finitedeformation) and on the choice of constitutive law is elucidated.This information is used to determine the reflection coefficientsfor reflection of either a (quasi-) shear wave or a (quasi-)longitudinal wave from the boundary of the half-space and tocharacterize the different cases which arise depending on thegeometry of the slowness section. The theoretical results are illustrated by numerical calculationsfor the range of possible types of behaviour with referenceforms of strain-energy function and different states of finitedeformation and to the question of stability of the half-space.     

Correlations of secondaries in events with a forward neutron at the ISR

Data, obtained from p-p collisions at centre-of-mass energies between 31 and 63 GeV, are presented on inclusive and semi-inclusive correlations between forward emitted neutrons and charged particles observed in an omnidirectional hodoscope. A total absorption spectrometer was used to detect the neutrons and to measure their energy. Significant correlations are observed over the whole rapidity range. The data suggest that neutrons result from the decay of clusters emitted in the fragmentation region.     

Proton-proton elastic scattering and nucleon resonance production at high energies

Angular distributions of proton-proton elastic scattering have been measured for incident beam momenta of 10.0, 12.0, 14.2 and 24.0 GeV/c over a range of lab scattering angles from 12 to 152 mrad. This is equivalent to a range of four-momentum transfer squared from about 0.1 to 6.7 GeV² at the highest momentum. Nucleon resonance production in the two-body reaction p + p → p + X has been studied at 24.0 GeV/c incident momentum from 13.5 to 112 mrad by measuring the proton momentum spectra from the elastic peak down to a momentum corresponding to a missing mass of about 2.6 GeV. The new data are compared with previous results and theoretical models.     

The energy dependence of the proton-proton total cross-section for centre-of-mass energies between 23 and 53 GeV

Measurements of proton-proton elastic scattering at angles around 6 mrad have been made at centre-of-mass energies of 23, 31, 45 and 53 GeV using the CERN Intersecting Storage Rings. The absolute scale of the cross-section was established by determination of the effective density of the colliding beans in their overlap region. Proton-proton total cross sections were deduced by extrapolation of the elastic differential cross-section to the forward direction and by application of the optical theorem. The results indicate that over the energy range studied the proton-proton total cross-section increases from about 39 to about 43 mb.     

Momentum spectra of secondary particles produced in proton-proton collisions at 14.2, 19.2 and 24.0 GeV/c

Results on charged particle yields in proton-proton collisions at 14.2, 19.2 and 24.0 GeV/c for secondary momenta above 4 GeV/c and lab angles between 10 and 150 mrad are reported. Cross sections for inclusive reactions involving the production of π^± K^±, p and $\text{p}$ are presented. The general features of the dependence of the data on transverse and longitudinal momentum, missing mass, and four-momentum transfer are described and the approach to limiting distributions in the 10 to 30 GeV energy range is discussed.     

New measurements of proton-proton total cross section at the CERN intersecting storage rings

Measurements of the proton-proton total cross section have been made with increased precision (±0.6%) over the ISR energy range $\text{s}\text{=23.5?62.7}\text{GeV}$. Two different experimental methods gave consistent results, showing that the total cross section increases 10% over the ISR range and in addition that the absolute value of the ISR luminosity can be measured to ±0.9%.