What is claimed is:
1. A polymeric composition which comprises
1. a matrix material which
(a) provides a continuous phase, and
(b) comprises precursors which will react together to form a crosslinked polymer;
and
2. a rheological modifier (RHM) which
(a) comprises a crystalline polymer having an onset of melting temperature To and a peak melting temperature Tp which is (i) from 20 C. to 200 C., and (ii) such that TpTo is less than Tp0.7,
(b) is uniformly distributed in the matrix material,
(c) is at least partially soluble in the matrix material when the composition is subjected to a treatment which consists of maintaining the composition at a temperature above Tp under conditions such that the precursors do not react together to form a crosslinked resin, and
(d) becomes at least partially insoluble in the matrix material when the composition is subjected to said treatment at a temperature above Tp and is then cooled to a temperature below To,
the composition
(A) having a viscosity above Tp which is less than its viscosity below Tp; and
(B) having a viscosity at a temperature below To which is substantially greater than the viscosity at the same temperature of a composition which is identical except that it does not contain the rheological modifier.
2. A composition according to claim 1 wherein the matrix material and the RHM and the relative amounts thereof are such that the composition, in the absence of any solid fillers, has a viscosity at (Tp10) C. which is at least twice its viscosity at (Tp10) C.
3. A composition according to claim 2 which has a viscosity at (Tp10) C. which is at least 5 times its viscosity at (Tp10) C.
4. A composition according to claim 2 wherein the matrix material and the RHM and the relative amounts thereof are such that the composition, in the absence of any solid non-polymeric fillers, has a viscosity at 20 C. which is at least twice the viscosity at 20 C. of a composition which is identical except that it does not contain the RHM.
5. A composition according to claim 4 which has a viscosity at 20 C. which is at least 5 times the viscosity at 20 C. of a composition which is identical except that it does not contain the RHM.
6. A composition according to claim 1 wherein the crystalline polymer is an SCC polymer.
7. A composition according to claim 6 wherein (TpTo) is less than 10 C.
8. A composition according to claim 7 wherein Tp is from 25 to 120 C.
9. A composition according to claim 8 wherein Tp is from 35 C. to 70 C.
10. A composition according to claim 6 wherein the crystalline polymer comprises (a) units derived from a monomer containing an n-alkyl group containing 12 to 50 carbon atoms and (b) at least 10% of units derived from a second monomer; and the matrix material comprises at least 10% of the second monomer or of units which are part of a polymer and are derived from the second monomer.
11. A composition according to claim 10 wherein the crystalline polymer contains 10 to 50% of units derived from the second monomer, and the matrix material contains 20 to 50% of the second monomer.
12. A composition according to claim 11 wherein the second monomer is styrene.
13. A composition according to claim 10 wherein the crystalline polymer contains 10 to 50% of units derived from the second monomer, and the matrix material comprises a polymer containing 10 to 70%, based on the matrix material, of units derived from the second monomer.
14. A composition according to claim 13 wherein the matrix material comprises precursors for an acrylate polymer and the second monomer is an alkyl acrylate or an alkyl methacrylate in which the alkyl group contains 1 to 4 carbon atoms.
15. A composition according to claim 1 wherein the matrix material comprises an unsaturated polyester and a copolymerizable monomer.
16. A composition according to claim 1 wherein the matrix material comprises precursors for an epoxy resin.
17. A composition according to claim 1 which is in the form of a sheet molding composite.
18. A composition according to claim 1 which is at a temperature below To and which has at least one of the following characteristics
(1) at least 30% by weight of the crystalline polymer is present in the form of discrete volumes which do not contain any material which takes part in the reaction which forms the crosslinked polymer,
(2) the composition, if it is maintained at 40 C., doubles in viscosity in less than 240 hours, e.g., in less than 24 hours,
(3) the RHM is not present in the form of discrete particles, and
(4) when the composition is heated from (Tp10) C. to (Tp10) C., there is an increase by a factor of less than 50, in the effective concentration of each of the materials which takes part in the reaction which forms the crosslinked polymer.
19. A method of making a composition as defined in claim 1 which comprises
(A) dispersing the RHM in at least part of the matrix material;
(B) heating the product of step (A) to a temperature above Tp under conditions such that the precursors do not react together to form a crosslinked polymer; and
(C) cooling the heated dispersion to a temperature below Tp.
20. A method of making a crosslinked polymer which comprises subjecting a composition as defined in claim 1 to conditions which cause the precursor to react to form a crosslinked polymer.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An assembly for endoscope, comprising:
a tubular member at its external wall thereof having a first threaded portion, a second threaded portion, and a threadless middle portion located between the first and second threaded portions;
a positioning ring having a threaded part formed at an internal wall thereof and threaded with the second threaded portion of the tubular member, the positioning ring being axially movable along the tubular member by means of the aforesaid threaded connection; and
a sleeve having an opening and a threaded section formed at an internal wall thereof, the threaded section being shorter than the middle portion, the sleeve being threadedly sleeved onto the tubular member through the opening, the threaded section being located at the middle portion of the tubular member, the threaded section being stopped against an opposite end of the first threaded portion with respect to the middle portion, the positioning ring having a distal end pushed distally against the sleeve to position the sleeve onto the tubular member.
2. The assembly as defined in claim 1, wherein the tubular member comprises an opening and a body; the first threaded portion extends toward the body from the opening; the second threaded portion being located at the body.
3. The assembly as defined in claim 2, wherein the tubular member comprises a stopping portion located at an opposite end of the second threaded portion with respect to the opening for stopping the positioning ring from disengagement from the tubular member toward its rear end behind the second threaded portion.
4. The assembly as defined in claim 1, wherein the middle portion is smaller than the first and second threaded portions in external diameter to allow the positioning ring to be slidably moved along the middle portion.
5. The assembly as defined in claim 1, wherein threaded section of the sleeve is spaced from the opening.
6. The assembly as defined in claim 5, wherein the sleeve comprises a through hole running through an external wall thereof, a fully reflecting mirror being mounted in the sleeve and corresponding to the through hole.
7. The assembly as defined in claim 6, wherein the sleeve comprises a bevel formed at the through hole in sectional view; the fully reflecting mirror comprises a front surface aligned with the bevel.
8. The assembly as defined in claim 1, wherein external diameters of the first threaded portion and the second threaded portion are equal.
9. The assembly as defined in claim 1, wherein the sleeve is threadedly sleeved directly onto the tubular member through the opening.