Lateral compliance

For orthorhombic symmetry on the other hand, tensile creep and lateral compliance measurements on specimens cut from oriented sheet will yield only 6 of the 9 required creep functions those not accessible by this method being Suit), Sssit) and S66(t)- The two shear compliances 555(1) and Seeit) can be obtained by torsional creep experiments, but these need to be carefully designed and involve complex experimental procedures. The only possibility for measurement of Su(t) on sheet appears to be by compressive creep techniques, however, one would expect substantial experimental difficulties largely associated with strain measurement and specimen geometry. There appears to be no reported evaluation of the full characterisation of creep for the case of orthorhombic synunetry. 

Fig. 6. Variation of lateral compliance with time during tensile creep of specimens cut at 0 and 90° to the fibre axis of a sheet of oriented polymethylmethacrylate (drawn at I24°C, birefringenceO-(X)l). Note that the values of the lateral compliances...

At low draw ratios, the tensile compliances (as distinct from the lateral compliances) exhibited appreciable time-dependence, with a marked anisotropy in their rate of change with time. As the draw ratio increased, the time dependence, and its anisotropy, decreased until, at very high draw ratio, the low creep rates presented earlier were obtained with no significant anisotropy of time-dependence. Data at draw ratios of 1-4 and 20 are presented in Figs. 10 and 11 (from Qayton ). 

The behaviour of the lateral compliance, S13, is similar to that of 533 but the behaviour of S12 at low draw ratio is worthy of note. Thus, on applying the creep load, an initial decrease in specimen thickness is followed first by a slight time dependent thickening and then the more usual time dependent decrease in thickness. No explanation has yet been offered for this unexpected effect. It has also been observed in LDPE drawn at 90°C and is completely reproducible and experimentally significant. ... 

For a pol3oner film possessing orthorhombic s3onmetry there are three lateral compliances 512, 513 and 533, which relate to the six Poisson s ratios previously defined. 

The lateral compliances S12 and S23 correspond to the contraction in the 2 direction (the thickness direction) for stresses applied along the 1 and 3 directions respectively (Figure 8.2). Several techniques have been developed for this measurement, the earliest being due to Saunders and co-workers who developed an apparatus to measure both... 

The Clean Air Act Amendments of 1990 put a heavy burden on the Environmental Protection Agency (EPA) and state agencies to permit and oversee compliance with the Clean Air Act (CAA). Table 24-1 lists the major deadlines affecting industry under the 1990 amendments. Some of the deadlines have already passed without any action" being promulgated and finalized. The other deadlines may also slip to a later date. Almost no statutorv "hammers" have been included in CAAA90. 

Tackifying resins enhance the adhesion of non-polar elastomers by improving wettability, increasing polarity and altering the viscoelastic properties. Dahlquist [31 ] established the first evidence of the modification of the viscoelastic properties of an elastomer by adding resins, and demonstrated that the performance of pressure-sensitive adhesives was related to the creep compliance. Later, Aubrey and Sherriff [32] demonstrated that a relationship between peel strength and viscoelasticity in natural rubber-low molecular resins blends existed. Class and Chu [33] used the dynamic mechanical measurements to demonstrate that compatible resins with an elastomer produced a decrease in the elastic modulus at room temperature and an increase in the tan <5 peak (which indicated the glass transition temperature of the resin-elastomer blend). Resins which are incompatible with an elastomer caused an increase in the elastic modulus at room temperature and showed two distinct maxima in the tan <5 curve. 

The results of the design review should be documented in a report rather than minutes of a meeting, as it represents objective evidence that may be required later to determine product compliance with requirements, investigate design problems, and compare similar designs. The report should have the agreement of the full review team and should include ... 

If performed appropriately airway clearance techniques provide similar clearance results, so choice should be based on patient preference and compliance. Airway clearance therapy is typically performed once or twice daily for maintenance care and is increased to three or four times per day for acute exacerbations. Inhaled medications are usually given with the therapies and will be discussed in a later section. 

The creep (/) at time / depends on the compliance function J(t), which is a characteristic of the polymer at a given temperature, and on the initial stress time scale has to be employed in J (i.e., ( -0 the time over which that stress was applied. Furthermore, while (0 for any load is given by the product AO17, the stress of concern is the incremental added stress or... 

Describe individual items of equipment and how they are connected in sufficient detail to enable unambiguous set-up. List minimum performance requirements and verification requirements, cross-referenced to the calibration section and any relevant instrument manuals. Number for later reference. For glassware, include grade where applicable (bear in mind that use of a particular grade may require justification and that proof of compliance may be required). Include environmental requirements (fume cupboards, etc.). 

After a prioritized list of processes is developed, a plan for PrHAs can be established. This plan must follow the minimum schedule in the PSM Rule, listed in Section 2.2.1, with no less than one-fourth of the PrHAs completed by May 26, 1994 and one-fourth completed each succeeding year. All PrHAs must be completed by May 26, 1997. However, the PSM Rule also states that PrHAs are to be done "as soon as possible, but no later than [the following schedule...]." This point is stated explicitly in the OSHA inspector s compliance guidelines, so it must be demonstrated that scheduled PrHAs were completed before the annual deadlines and that no intentional delays were incorporated into the PrHA schedule. For example, a large site might have mostly office and laboratory facilities, and only two processes covered by the PSM Rule. If manpower is available to conduct two PrHAs in parallel within the first year, then the PrHA schedule should not be extended over a 3-year period. 

In addition to summarizing very briefly the scope of each major section of the Act, E.H. Hurst contrasted the self-implementing sections that became effective immediately and those sections with later timetables for EPA s rule-making and implementation. In the first class are Sec. 8(e), notices of "Substantial Risks," and Sec. 5, "Premanufacturing Notices" of intent to manufacture or process a new chemical substances. Over 400 Sec. 8(e) notices and some 1200 "PMN s" under Sec. 5(e) have been sent to EPA — substantial evidence of compliance. 

Evaluation is undertaken by the ECHA (see below) to evaluate testing proposals made by industry or to check compliance with the registration requirements. The ECHA will also coordinate substance evaluation by the authorities to investigate chemicals with perceived risks. This assessment may be used later to prepare proposals for restrictions or authorization. Substances with properties of very high concern will be made subject to authorization the ECHA will publish a list containing such candidate substances. Applicants will have to demonstrate that risks associated with uses of these substances are adequately controlled or that the socioeconomic benefits of their use outweigh the risks and there are no suitable alternative substitute substances or technologies. 

---