Composition for a Molded Body

1 . A composition for a molded body comprising a recombinant spider silk protein and a plasticizer, wherein the composition is capable of being induced into a flowable state, wherein the recombinant spider silk protein is substantially non-degraded in the flowable state.

2 .- 37 . (canceled)

38 . A process for preparing a molded body, comprising the steps of:

(a) applying pressure and shear force to a composition comprising a recombinant spider silk protein and a plasticizer to transform the composition to a flowable state, and

(b) extruding the composition in the flowable state to form a molded body.

39 . The process of claim 38 , wherein extruding the composition to form a molded body comprises extruding the composition to form a fiber or extruding the composition into a mold.

40 . The process of claim 39 , wherein extruding the composition to form a fiber comprises extruding the composition through a spinneret.

41 . (canceled)

42 . The process of claim 38 , further comprising:

(a) applying pressure and shear force to the molded body to transform the molded body to a composition in a flowable state, and

(b) extruding the composition in the flowable state to form a second molded body.

43 . The process of claim 42 , further comprising repeating steps (a) and (b) to the second molded body at least once.

44 . The process of claim 38 , wherein said shear force is from 1.5 to 13 Nm.

45 . (canceled)

46 . The process of claim 38 , wherein the shear force and pressure are applied to the composition using a capillary rheometer or a twin screw extruder.

47 . The process of claim 46 , wherein the screw speed of the twin screw extruder ranges from 10 to 300 RPM during application of said pressure and shear force.

48 . The process of claim 38 , wherein an instrument used to apply the shear force and pressure comprises a mixing chamber that is coupled to and proximal to an extrusion chamber.

49 . The process of claim 48 , wherein the composition is heated in the mixing chamber or in the extrusion chamber.

50 . (canceled)

51 . The process of claim 49 , wherein the composition is heated to a temperature of less than 120° C., less than 80° C., or less than 40° C.

52 . (canceled)

53 . (canceled)

54 . The process of claim 38 , wherein the molded body after extrusion has a loss of water content of less than 15% as compared to the composition before extrusion.

55 . (canceled)

56 . The process of claim 48 , wherein the composition has a residence time in the mixing chamber ranging from 3 to 7 minutes.

57 . The process of claim 48 , wherein the extrusion chamber is tapered proximal to an orifice through which the composition is extruded.

58 . The process of claim 48 , wherein the extrusion chamber is temperature controlled.

59 . The process of claim 48 , wherein the molded body is a fiber and the fiber is hand drawn or the fiber is drawn over multiple steps.

60 . (canceled)

61 . The process of claim 48 , wherein the recombinant spider silk protein is substantially non-degraded in the molded body.

62 . The process of claim 61 , wherein the recombinant spider silk protein is degraded in an amount of less than 10% by weight, less than 6% by weight, or less than 2% by weight in the molded body.

63 . (canceled)

64 . (canceled)

65 . The process of claim 62 , wherein the degradation of the recombinant spider silk protein is assessed by measuring the amount of full-length recombinant spider silk protein present in the composition before and after extrusion using size exclusion chromatography.

66 . (canceled)

67 . The process of claim 38 , wherein the molded body has minimal birefringence as measured by polarized light microscopy.

68 . The process of claim 38 , wherein the composition is induced into the flowable state through the application of shear force ranging from 1.5 Nm to 13 Nm.

69 . The process of claim 38 , wherein the composition is induced into the flowable state through the application of pressure ranging from 1 Mpa to 300 Mpa.

70 . The process of claim 38 , wherein the composition has a melt flow index of at least 0.5, at least 1, at least 2, or at least 5 as tested per ASTM D1238 at 95° C. with a load of 2.16 kg.

71 . The process of claim 38 , wherein the recombinant spider silk protein comprises at least two occurrences of a repeat unit, the repeat unit comprising:

more than 150 amino acid residues and having a molecular weight of at least 10 kDa;

an alanine rich region with 6 or more consecutive amino acids, comprising an alanine content of at least 80%; and

a glycine rich region with 12 or more consecutive amino acids, comprising a glycine content of at least 40% and an alanine content of less than 30%.

72 . The process of claim 38 , wherein the plasticizer is selected from a polyol, water, and urea.

73 . The process of claim 38 , wherein the molded body is a fiber.

74 . The process of claim 73 , wherein the fiber has a strength in the range of 100 Pa to 1.2 Gpa.