Algal plastics - Patent Review 5352709

What is claimed:

1. A foamed packing material comprising a foamed and stabilized filamentous algal fiber matrix having substantial dimensional stability.

2. The foamed packing material of claim 1, further comprising an application additive selected from the group consisting of antioxidants, antistatic agents, compatibilizers, flame retardants, heat stabilizers, water repellents, impact modifiers, lubricants, ultraviolet stabilizers, biocides, pigments, colorants, fillers, impact modifiers/plasticizers, foam stabilizers, viscosity modifiers, and combinations thereof.

3. The foamed packing material of claim 2, wherein said application additive is admixed with an algal pulp during a process of generating said algal fiber matrix.

4. The foamed packing material of claim 2, wherein said application additive is used to coat said algal fiber matrix in a post-coating process.

5. The foamed packing material of claim 1, further comprising an additional polysaccharide component.

6. The foamed packing material of claim 5, wherein said additional polysaccharide component is selected from the group consisting of unmodified vegetable starches, modified vegetable starches, alginates, glycosaminoglycans, hexosamines, pentosans, guar gums, cellulose, methylcellulose, hydroxypropyl cellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, hydroxypropylbutylmethylcellulose, sodium carboxy methylcellulose, polyvinyl-pyrrolidone bentonite, agar, dextran, chitin, polymaltose, polyfructose, pectin, and combinations thereof.

7. The foamed packing material of claim 1, further comprising a high gluten starch.

8. The foamed packing material of claim 1, further comprising a protein component.

9. The foamed packing material of claim 8, wherein said protein component comprises a fibrous protein which increases the dimensional stability of said algal fiber matrix.

10. The foamed packing material of claim 8, wherein said protein component comprises a dietary source of protein for digestion by an animal.

11. The foamed packing material of claim 1, further comprising an additional impact modifier/plasticizer.

12. The foamed packing material of claim 11, wherein said additional plasticizer is selected from the group consisting of polyethylenes, polyisobutylenes, polypropylenes, poly(vinyl chlorides), poly(vinyl acetates), polyvinyl alcohols, polystyrenes, polyacrylonitriles, polyvinylcarbazols, polyamides, essentially water-insoluble poly(acrylates), essentially water-insoluble poly(methacrylates), poly(lactic acids), poly(hydrobutyrate-co-hydroxyvalerates), methacrylate-acrylonitrile-butadiene-styrene, acrylonitrile-butadiene-styrene, chlorinated polyoethylene, polyvinyl alcohols, ethylene-vinyl acetate, polyolefines, polyacetals, thermoplastic polycondensates, polyarylethers, polyimdies, alkylene/vinyl ester-copolymers, ethylene/vinyl alcohol-copolymers, alkylene/acrylates coploymers, methacrylate coploymers, ethylene/ethyl acrylate-copolymers, ethylene/methyl acrylate-copolymers, ABS-copolymers, styrene/acrylonitrile-copolymers, alkylene/maleic anhydride copolymers, acrylamide/acrylonitrile copolymers, polyvinyl acetatephthates, polyvinyl pyrolidone, poly(alkylene oxides), poly(propylene glycols), poly(ethylene-propylene glycols), polyisobutylenes, lignin acrylamides, lignin 2-hydroxyethylmethercrylates, glycerol, pentaerythritol, glycerol monoacetate, diacetates, triacetates, propylene glycol, sorbitol, sodium diethylsulfosuccinate, triethyl citrate, tributyl citrate, and mixtures thereof.

13. The foamed packing material of claim 1, wherein said algal fiber matrix is derived from an algal pulp generated from filamentous algae selected from the division Chlorophyta.

14. The foamed packing material of claim 13, wherein said filamentous algae is selected from the order Cladophorales.

15. The foamed packing material of claim 13, wherein said filamentous algae is Cladophora glomerata Kuetzing.

16. The foamed packing material of claim 1, wherein each component of said packing material is selected so as to render said packing material substantially biodegradable.

17. The foamed packing material of claim 1, wherein said algal fiber matrix is formed in a shape of a molded packing.

18. The foamed packing material of claim 1, wherein said algal fiber matrix is formed in a shape of a packing particle.

19. A foamed packing material comprising a foamed and stabilized algal fiber matrix having substantial dimensional stability, said fiber matrix comprising filamentous algal fibers and starch, wherein said foamed packing material is substantially biodegradable.

20. The foamed packing material of claim 19, wherein said starch comprises a high gluten starch.

21. A foamed packing material comprising a isocyanate foamed and cross-linked filamentous algal fiber matrix having substantial dimensional stability.

22. A method of forming a foamed packing material comprising subjecting a filamentous algal pulp to a foaming process which results in a foamed algal fiber matrix having substantial degree of dimensional stability.

23. The method of claim 22, wherein said foaming process comprises an isocyanate based foaming technique to generate said foamed algal fiber matrix.

24. The method of claim 23, wherein said isocyanate base foaming technique comprises admixing with said algal pulp an amount of an isocyanate, a catalyst and a blowing agent sufficient to generate said foamed algal fiber matrix and cross-link said fibers of said foamed algal fiber matrix to provide a substantial degree of dimensional stability.

25. The method of claim 24, wherein said foaming process further comprises admixing with said algal pulp an additive selected from the group consisting of a polyol, a starch, and a combination thereof.

26. The method of claim 25, wherein said starch is a high gluten starch.

27. The method of claim 22, wherein said foaming process comprises volatilizing a volatile component in said algal pulp.

28. The method of claim 27, wherein said volatile component is volatilized by the application of thermal energy to said algal pulp.

29. The method of claim 28, wherein said thermal energy is applied to said suspension using a thermal energy source selected from the group consisting of a microwave system and an extruder system.

30. The method of claim 27, wherein said volatile component is volatilized by thermal energy generated by an exothermic reaction occurring in said suspension.

31. The method of claim 27, wherein said volatile component is water.

32. The method of claim 27, wherein said volatile component is a blowing agent admixed with said algal pulp.

33. The method of claim 22, wherein said foaming process comprises carrying out a chemical reaction which results in an evolution of gases in a suspension of said algal pulp.

34. The method of claim 33, wherein said evolved gas is carbon dioxide.

35. The method of claim 33, wherein said evolved gas is nitrogen.

36. The method of claim 33, wherein said chemical reaction is a thermal decomposition of a chemical blowing agent.

37. The method of claim 22, wherein said foaming process comprises applying a vacuum to a suspension of said algal pulp to vacuum expand a gas dissolved in said suspension.

38. The method of claim 22, wherein said foaming process comprises whipping a gas into a suspension of said algal pulp.

39. The method of claim 22, wherein said foaming process comprises admixing, in a suspension of said algal pulp, crystals which are soluble in a solvent in which said algal pulp is insoluble, and dissolving said crystals with said solvent in a substantially dried mixture of said crystals and said algal pulp.

40. The method of claim 22, wherein said algal pulp is prepared by pulping a filamentous algal mass using a pulping process selected from the group consisting of a mechanical pulping process, a chemical pulping process, a biological pulping process, and combinations thereof.

41. The method of claim 22, wherein said algal pulp is further prepared by admixing at least one application additive with said pulped algal mass.

42. The method of claim 41, wherein said application additive is selected from the group consisting of antioxidants, antistatic agents, compatibilizers, flame retardants, heat stabilizers, water repellents, impact modifiers, lubricants, ultraviolet stabilizers, biocides, pigments, colorants, fillers, impact modifiers/plasticizers, foam stabilizers, viscosity modifiers, and combinations thereof.

43. The method of claim 22, wherein said foamed algal fiber matrix is formed in a shape of a molded packing material.

44. The method of claim 22, wherein said foamed algal fiber matrix is formed in a shape of packing particles.

45. A foamed packing material comprising a foamed and stabilized filamentous algal fiber matrix having substantial dimensional stability and lacking isocyanates.

46. The foamed packing material of claim 45, further comprising an application additive selected from the group consisting of antioxidants, antistatic agents, compatibilizers, flame retardants, heat stabilizers, water repellents, impact modifiers, lubricants, ultraviolet stabilizers, biocides, pigments, colorants, fillers, impact modifiers/plasticizers, foam stabilizers, viscosity modifiers, and combinations thereof.

47. The foamed packing material of claim 45, further comprising an additional polysaccharide component.

48. The foamed packing material of claim 47, wherein said additional polysaccharide component is selected from the group consisting of unmodified vegetable starches, modified vegetable starches, alginates, glyeosaminoglycans, hexosamines, pentosans, guar gums, cellulose, methylcellulose, hydroxypropyl cellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, hydroxypropylbutylmethylcellulose, sodium carboxy methylcellulose, polyvinyl-pyrrolidone bentonite, agar, dextran, chitin, polymaltose, polyfructose, pectin, and combinations thereof.

49. The foamed packing material of claim 45, further comprising a high gluten starch.

50. The foamed packing material of claim 46, wherein said additional plastcizer is selected from the group consisting of polyethylenes, polyisobutylenes, polypropylenes, poly(vinyl chlorides), poly(vinyl acetates), polyvinyl alcohols, polystyrenes, polyacrylonitriles, polyvinylcarbazols, polyamides, essentially water-insoluble poly(acrylates), essentially water-insoluble poly(methacrylates), poly(lactic acids), poly(hydrobutyrate-co-hydroxyvalerates), methacrylate-acrylonitrile-butadiene-styrene, acrylonitrile-butadiene-styrene, chlorinated poly-ethylene, polyvinyl alcohols, ethylene-vinyl acetate, polyolefines, polyacetals, thermoplastic polycondensates, polyarylethers, polyimides, alkylene/vinyl ester-copolymers, ethylene/vinyl alcohol-copolymers, alkylene/acrylates copolymers, methacrylate copolymers, ethylene/ethyl acrylate-copolymers, ethylene/methyl acrylate-copolymers, ABS-copolymers, styrene/acrylonitrile-copolymers, alkylene/maleic anhydride copolymers, acrylamide/acrylonitrile copolymers, polyvinyl acetatephthates, polyvinyl pyrolidone, poly(alkylene oxides), poly(propylene glycols), poly(ethyleneopropylene glycols), polyisobutylenes, lignin acrylamides, lignin 2-hydroxyethylmethercrylates, glycerol, pentaerythritol, glycerol monoacetate, diacetates, triacetates, propylene glycol, sorbitol, sodium diethylsulfosuccinate, triethyl citrate, tributyl citrate, and mixtures thereof.

51. The foamed packing material of claim 45, wherein said filamentous algal fiber matrix comprises fiber of a filamentous green algae selected from the order Cladophorales.

52. The foamed packing material of claim 51, wherein said filamentous green algae is Cladophora glomerata Kuetzing.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

Foamed packing materials have become a major component of the packing industry because of their strength, light weight, and shock absorptive and insulating capacities. Until recently nearly all of the foamed packing materials, loose and molded, were made from polystyrene resins. These resins have excellent properties, and form the standard against which other packing materials are measured.

Solid foamed packing materials are used wherever optimum inherent shock absorbance and thermal insulation are required. The former is the most important factor in solid molded packings for shipping protection of electronics and other fragile materials including business machines, electrical components, computers, tools, major appliances, hardware, and toys. The latter is more important in applications such as cups for hot liquids or molded packings for the insulation of warm foods. Cups for hot liquids obviously also depend upon non-dissolution of these materials in water.

The majority of plastics fall into the category of petro-plastics, which are a non-energy product of petroleum chemicals. Petroleum-based plastics are considered to be nonbiodegradable, or at best only slowly biodegradable. This, coupled with the amount of plastics produced and ending up as litter or in landfills, is primarily responsible for the activity towards plastics that are biodegradable. In the U.S. alone, about 58 billion pounds of petroleum-derived plastics were produced in 1989. Municipal solid waste contains 7% by weight and 17-25% by volume of plastics, largely from packing materials. While traditional plastics can be altered to enable facile chemical degradation, the toxicity of the residues have yet to be defined.

Replacement of petrochemically based plastics by biologically derived plastics would reduce petroleum usage. Litter from such plastics would disappear into its surroundings to leave only normal biological residues. Integrated waste management practices that include off-landfill composting of biodegradable wastes, incineration, some reduction of packaging materials, and recycling could help bring waste disposal under control.

For several years there has existed an interest in developing biodegradable loose packings from vegetable materials. These materials are generally made from corn and other starches and can include the addition of other materials which act to enhance polymerization, chemical crosslinking, or flexibility. These loose packings have been formed by a variety of standard foaming and extrusion methods derived from polystyrene foam production, or the extrusion or explosive popping of cereal foods. However, these largely starch-based materials are often not well suited for many applications of solid packing foams because of their relatively rapid breakdown under wet conditions, and their inherently low breaking strengths.

SUMMARY OF THE INVENTION

This invention pertains to foamed algal plastics and products made therefrom, and methods for making algal plastics. The invention also pertains to algal plastic resin precursors for generating the foamed algal plastics and algal plastic products. The foamed algal plastics comprise a foamed and stabilized algal fiber matrix having substantial dimensional stability. The foamed algal plastics can be used, for instance, to generate packing materials, such as molded packings or loose particles packings (e.g. packing "peanuts").

The algal plastics and algal plastic precursors are made from filamentous green algae of the Division Chlorophyta, Class Chlorophycaeae, and Order Cladophorales, and include at least the following genera: Cladophora, Chaetomorpha, Rhizoclonium, Pithophora, Valonia, Valoniopsis, Cladophoropsis, Boergesenia, Anadyomene, Microdictyon, Boodlea, Chamacdoris, and Dictyosphaeria. For example, the species Cladophora glomerata Kuetzing can be used to form the algal plastics of the present invention.

The algal plastics can also include application additives, such as antioxidants, antistatic agents, compatibilizers, flame retardants, heat stabilizers, water repellents, impact modifiers, lubricants, ultraviolet stabilizers, biocides, pigments, colorants, fillers, impact modifiers/plasticizers, foam stabilizers, viscosity modifiers, and combinations thereof. The application additives can be mixed into an algal pulp before or concurrently with the generation of the algal fiber matrix, or can be used to coat the already formed algal plastic. For example, the algal plastic can include, an additional polysaccharide component, such as unmodified vegetable starches, modified vegetable starches, alginates, glycose-amino- glycans, hexosamines, pentosans, guar gums, cellulose, methylcellulose, hydroxypropyl cellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, hydroxypropylbutylmethylcellulose, sodium carboxy methylcellulose, polyvinyl- pyrrolidone bentonite, agar, dextran, chitin, polymaltose, polyfructose, pectin, and combinations thereof. For instance, a high gluten starch, such as starch isolated from sticky rice, can be added to the algal pulp and incorporated into the algal fiber matrix of the plastic.

The foamed algal plastics can be formed by subjecting an algal pulp to foaming process which produce cellular plastic foams, including, for example, isocyanate base techniques, volatization of component(s) of the algal pulp such as blowing agents or water, vacuum expanding gases disolved in the algal pulp, whipping gases into the algal pulp, and dissolving crystals or other small particles into the pulp and subsequently removing them after stabilization of the foam.

The algal plastics and algal plastic products of the present invention provide unique advantages. For instance, in terms of environmental concerns, the use of algae in plastic engineering can lead to a decreased use of synthetic polymers which would otherwise require the use of a greater amount of environmentally hazardous chemicals, such is of concern when petrochemical are used. The algal plastics can be formulated so as to be biodegradable and/or recyclable. Furthermore, the dimensional stability qualities of the algal plastics can be within the range of synthetic plastics used in the same or similar applications.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a 20% by volume foamed algal plastic generated by a polyurethane foaming method.

FIG. 2 is a cross-sectional view of a 40% by volume foamed algal plastic generated by a polyurethane foaming method.

FIG. 3 is a cross-sectional view of a 60% by volume foamed algal plastic generated by a polyurethane foaming method.

FIG. 4 is an micrograph of the surface of a 20% by volume foamed algal plastic generated by a polyurethane foaming method.

FIG. 5 is an micrograph of the surface of a 40% by volume foamed algal plastic generated by a polyurethane foaming method.

FIG. 6 is an micrograph of the surface of a 60% by volume foamed algal plastic generated by a polyurethane foaming method.

FIG. 7 is a plot of the compressive strength versus density of 40% by volume algal plastic foams of different densities, the algal plastics generated by a polyurethane foaming method. Compressive strength data from algal plastic samples generated by using finely ground algae are indicated by (.DELTA.), and compressive strength data for plastics generated with coarsely ground algae are represented by (.smallcircle.). Also included in the plot are data values for expanded polystyrene ( ) and extruded polystyrene( ).

FIG. 8 is a plot of the compressive strength versus density of 70% by volume algal plastic foams of different densities.

FIG. 9 is a plot of the compressive strength versus density of 60% by volume algal plastic foams of different densities.

DETAILED DESCRIPTION OF THE INVENTION

The algal fibers and algal plastic resins described herein are well-suited to the formation of both loose and solid packings. Where desirable, the components of the algal plastics can be chosen so as to produce an end product made so as to be almost entirely biodegradable.

The algal fibers, pulps, resins, and plastics described herein are unique structural combinations of cellulose, hemicelluloses, sugars, and proteins. It has been discovered that algae are well-suited as raw materials for molded foams and other plastic applications as they contain polysaccharides such as cellulose, as inherent structural components of the cell walls. In most instances, the cellulose is arrayed in long fibers made up of complex microfibrillar layers. Other materials that can play an important role in certain molding processes are also found in algae, and include sugars rich in hydroxy groups as well as structural glucosamines and proteins.

Among the green algae in the Class Chlorophyceae, the filamentous algae of the order Cladophorales are especially well suited for making the algal plastics of the present invention. These algae have long macrofibrillar structures made up of cellulosic chains, and the underlying structure of these microfibrillar layers is complex and inherently strong. Additionally, algae of the order Cladophorales are particularly rich in cellulose.

Moreover some of these algae, such as Cladophora glomerata (L.) Kutzing, have become major ecological pests, reaching massive nuisance proportions as a result of eutrophication caused by pollutants in effluent frown industry, agriculture and urban sewage. The organism adversely affects navigation, recreation, water quality, and property values. 30-percent of the aquatic herbicides used in the U.S. are for control of this pest. In addition to the benefits derived from the use of C. glomerata as a biodegradable replacement for polystyrene resins in such applications as foamed packing materials, its industrial use further represents an opportunity for cost effective, ecologically responsible pest control. Furthermore, some of the algae useful in generating the algal plastics of this invention may be grown in waste streams and effluent ponds from industrial and domestic waste disposal, and present an opportunity for a new renewable industrial resource to be grown in habitats not currently exploited.

The organisms specified for use for the purposes set forth in this patent application are filamentous green algae of the Division Chlorophyta, Class Chlorophycaeae, and Order Cladophorales.

The systematics of the order Cladophorales is summarized as follows. Cladophoraleans are straight chain and branched filamentous plants composed of multinucleate cells. The filaments are attached to the substrate by rhizomes or are free floating. The cells contain numerous discoid angular chloroplasts forming a parietal reticulum, but they may extend into the internal meshes of the protoplasmic foam. The main wall polysaccharide is a highly crystalline cellulose I, forming numerous lamellae of microfibrils in a crossed fibrillar pattern. In at least one species, Pithophora, the outer walls and cross walls contain n-glucosamines (chitin) as well as cellulose I. One or more species may contain silica in their outer cell walls. Reproduction can be by either sexual or asexual means.

The extremely complex and exact system of wall formation in the Cladophorales suggests that deposition is under very precise control and that the production and orientation of microfibrils is a function of the outermost layer of cytoplasm. The set of microfibrils are deposited in the sporeling cells with the first to be deposited making a small angle to the transverse axis, followed by the second at a greater angle, and finally the third, when present. The rhythm of deposition is retained by the daughter cells through several cell divisions so that adjacent cells in a filament have the innermost lamellae lying in the same direction.

Microfibrils normally are synthesized through the formation of terminal synthesizing complexes (TC), containing enzymes and other factors at their growing tip. TC structure determines final microfibrillar assembly in the cell walls of algae. There are two basic forms of these TC's; rosettes and linear.

The interactions of the chemical and physical properties of the cell walls of filamentous green algae provide form, strength and stability. These properties include:

1. Microfibrillar lamellae composed of cellulose I.

2. An amorphous matrix composed of polysaccharides, between the inner and outer walls or the filaments, which surrounds the microfibrillar lamellae.

3. Hemicelluloses concentrated on the outer surfaces of the microfibrils.

4. Chitin and chitosan in the outer and cross walls of some species.

5. Silica in the outer wall of some species.

6. Proteins, glycoproteins and heteropolysaccharides.

In general, the filaments of the cladophoralean algae are composed of cells enclosed by a double cell wall. The inner wall encloses individual cells, while the thinner outer wall ensheathes the whole filament. The mass of the cell wall is made up mostly of microfibrillar elements which provide rigidity and strength. The most common component of the microfibrils is the polysaccharide, cellulose. In the Cladophorales, a highly crystallized form of cellulose, cellulose I (or native cellulose) is present in all the species of the genera Cladophora, Chaetomorpha, Pithophora and Rhizoclonium, whereas it is replaced by cellulose II (a less polymerized form of cellulose with irregularly disposed molecules) in all Spongomorpha spp. The percentage of microfibrillar material in the genus Cladophora is about 28.5%, and in the genus Chaetomorpha is in the range of 36.5-41%.

In the cell wall, cellulose is usually laid down in the form of lamellae running in two directions, in steep or slow spirals, almost at right angles or with a third lamellae, if present, as in some species of Cladophora, Chaetomorpha and Valonia, in which the fibrils run in the obtuse angle between the other two. The third spiral is not always present, in which case the cell wall is a two lamellae repeat. Uniquely, microfibrils are interwoven between different bands of lamellae. The microfibrils of the side walls are continuous with those of the cross wall. The microfibrillar lamellae are in general surrounded by a water soluble amorphous material also composed of polysaccharides.

The polysaccharide composition of cladophoralean cell walls is, in general, as follows:

Cellulose microfibrils--Glucose, galactose, arabinose and xylose.

Water soluble fraction--Uronic Acid, galactose, glucose, arabinose, xylose.

Hemicellulose fraction--Galactoglucomannan, arabinoglucuronoxylan.

Other sugars represent the constituents of glycoproteins and heteropolysaccharide fragments that are linked to each other or to cellulose. Protein related in structure to collagen are also found.

In addition, silica is also found to a small extent in the cell walls of the cotton-mat algae.

The order Cladophorales is defined here to include at least the following genera: Cladophora, Chaetomorpha, Rhizoclonium, Pithophora, Valonia, Valoniopsis, Cladophoropsis, Boergesenia, Anadyomene, Microdictyon, Boodlea, Chamaedoris, and Dictyosphaeria. Because of the taxonomic state of flux, the order Cladophorales is further defined to include any filamentous green alga of the class Chlorophyceae with the cell wall characteristics, general chemical and physical composition, and structure and function as described above. The preferred species with reference to this invention are Cladophora spp., especially Cladophora glomerata Kuetzing, Chaetomorpha spp., Pithophora spp., and Rhizoclonium spp.

The species of preference to be harvested under current world conditions of pollution eutrophication is Cladophora glomerata Kuetzing. Worldwide, this species has the widest distribution and greatest biomass of all the filamentous green algae. In addition, this species is of the genus having the second highest proportion of cellulose I microfibrils in its cell walls. However, it will be appreciated by those skilled in the art that other Cladophora spp., Chaetomorpha spp., Pithophora spp., and Rhizoclonium spp., all contain cellulose I in their cell walls and can be utilized for the various formulations and applications described below.

For culturing, Cladophora glomerata Kuetzing, Chaetomorpha spp., Pithophora spp., and Rhizoclonium spp. will be used preferentially. Pithophora spp, for example, are generally free floating and tend to prefer non-flowing water, which makes them an excellent candidate for culture in polluted effluent pools. Ultimately, however, whichever cladophoralean species is most amenable to being bred or biologically engineered to provide the highest yields of the best quality cellulose and related hydrogen bond-inducing polysaccharides will be used. Strain improvement can be carried out by breeding under standard laboratory conditions of monoalgal culture, or by introducing genes using recombinant manipulation of the genome.

It is the inherent structure of the cladophoraleans that make them particularly suited as fibrous resins for the production of foamed packing materials. The complex microfibrillar structure in the Cladophorales can result in fibers having effective lengths on the order of a meter or more, and can be an important factor in the structural integrity of foamed packing material made from algae. These fibers are comprised primarily of cellulose I, a strong form of the polymer, and may also contain other strong structural materials such as glucosamines. The strength of these fibers is the result of the inherent cross-fibrillar structure described above. Furthermore these structure are surrounded by polysaccharide materials and sugars which can participate in stable foaming reactions so as to alleviate any need to substitute synthetic materials such as synthetic polyols. The integral high hemicellulose content of these algae, with its high hydroxyl group content, can be particularly advantageous for this purpose. The water soluble sugars, under dry pulping conditions, may also contribute to various foaming reactions. Even the inherent moisture content of the dried algal resins or pulps can be important to, for example, in steam explosion methods of foaming.

In particular, it is important that articles made from algal plastics retain sufficient strength and dimensional stability to perform their desired function (e.g. sufficient dimensional stability to serve as a packing material), and in some instances, maintain dimensional stability in humid air. For instance, the dimensional stability of the algal foam plastic can be within a range designated by the useful characteristics of extruded polystyrene and expanded polystyrene for the same or similar application as the algal foam plastic is being used in. In many applications, the article must also be recyclable and/or biodegradable after disposal. The tensile and compressive strengths of the final foamed product is not only influenced by the fibrillar structure itself, but can be influenced by the hydrogen bonding capacities of the accompanying hemicelluloses. The polysaccharides within the filamentous structure can also act like inherent polysaccharide glues that can further add cohesiveness to the foamed packing product. Finally, while the porosity and vegetative content of foams made from these algae make them inherently biodegradable, their relative hydrophobicity make them slow to absorb moisture and breakdown in normal use.

In many applications, the foamed algal fiber matrix which is created can have a low water content. In situations where its use requires a low inherent moisture content, the algal plastic can be dehumidified either in a step subsequent to the foaming process, or as part of the foaming process itself. Low moisture requirements may arise, for example, where the packing material will come in contact with moisture-sensitive material during its use, as well as where the stability of the algal fiber matrix is influenced by the moisture-content of the plastic.

For packing materials, the choice of resin to be created can often depend on the desired foaming and forming methodology used to create the algal plastic end products. By way of illustration, if an extrusion method for forming loose packings is used which is similar to the extrusion of polystyrene loose packing, it may be desirable to reduce fiber lengths during a pulping step, and release the hemicelluloses and starches from the algal mass. The ensuing pulp can then be cooked to a temperature where the hemicelluloses form an amorphous mass with the fibers embedded therein and create a relatively translucent resin that can be pelletized so as to contain a sufficient moisture content to explode upon heating in an extruder. If desired, the "popped" algal plastic can then be cut from the mass into shaped loose packings. Similar resins can be generated for use with microwave explosion puffers such as described by the Spratt et al. U.S. Pat. No. 4,990,348, incorporated by reference herein.

For the solid packing materials described herein, any pulping method, such as ones developed for paper and can be used to prepare an algal resin. (See for example commonly assigned U.S. patent application Ser. No. 07/928,978 entitled "Algal Pulps and Prepulps and Products made therefrom, incorporated by reference herein). It will be appreciated that the desired end product can control which particular pulping methodology is selected. Pulping and fiber preparation used in wood and nonwood-fiber processes (see for example Pulp and Paper Chemistry and Chemical Technology vol I ed. James Casey (1980) Wiley & Sons, NY;Papermaking ed. Francis Bolam (1965) Clowes & Sons, London, chapters 4 and 5; Chemical and Mechanical Pulping ed. James Casey (1984) Marcel Dekker, NY; and Joint Textbook Committee of the Paper Industry ed. T. Grace and E. Malcolm (1989) TAPPI, Atlanta, incorporated by reference herein) are generally applicable in making the cladophoralean pulps of the present invention. For most algal plastics, the object of pulping will be to maximize the retention of the fibrous structure of the alga. Therefore gentle, largely mechanical methods will generally be desirable. On the other hand, depending on the foaming method used, a pulping process can be employed which is designed to optimally expose or alter the inherent surface chemistry of the various polysaccharide components of the algal fiber. This is especially important, for example, when the method of forming the final foam involves the reacting of the hydroxyl groups of the resin with isocyanate to produce a cross-linked, strong material with a high percentage of algal fiber as its principal component.

Cladophoralean pulps can be produced by mechanical pulping, by gentle chemical action and selective extraction, by biological pulping, or by combinations thereof. The pulping method selected should

1) retain or create the optimum fiber length for the application, and

2) differentially select and/or expose the hemicelluloses and other sugar polymers so as to increase the hydroxyl group ratio or promote optimum hydrogen bonding capacity or increase the total proportion of cellulose in the mix.

Mechanical pulping of the algae can be performed using any of several different mechanical pulping techniques useful in pulping wood and non-wood fibers. Generally, the length of the fiber desired in the algal plastic will determine which process is used, as well as the duration of pulping. Examples of mechanical pulping processes include